rev 59939 : [mq]: 8243974-investigate-millis-since-last-gc-move
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 resize_heap_if_necessary();
1039
1040 // Rebuild the strong code root lists for each region
1041 rebuild_strong_code_roots();
1042
1043 // Purge code root memory
1044 purge_code_root_memory();
1045
1046 // Start a new incremental collection set for the next pause
1047 start_new_collection_set();
1048
1049 _allocator->init_mutator_alloc_regions();
1050
1051 // Post collection state updates.
1052 MetaspaceGC::compute_new_size();
1053 }
1054
1055 void G1CollectedHeap::abort_refinement() {
1056 if (_hot_card_cache->use_cache()) {
1057 _hot_card_cache->reset_hot_cache();
1058 }
1059
1060 // Discard all remembered set updates and reset refinement statistics.
1061 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1062 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1063 "DCQS should be empty");
1064 concurrent_refine()->get_and_reset_refinement_stats();
1065 }
1066
1067 void G1CollectedHeap::verify_after_full_collection() {
1068 _hrm->verify_optional();
1069 _verifier->verify_region_sets_optional();
1070 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1071 // Clear the previous marking bitmap, if needed for bitmap verification.
1072 // Note we cannot do this when we clear the next marking bitmap in
1073 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1074 // objects marked during a full GC against the previous bitmap.
1075 // But we need to clear it before calling check_bitmaps below since
1076 // the full GC has compacted objects and updated TAMS but not updated
1077 // the prev bitmap.
1078 if (G1VerifyBitmaps) {
1079 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1080 _cm->clear_prev_bitmap(workers());
1081 }
1082 // This call implicitly verifies that the next bitmap is clear after Full GC.
1083 _verifier->check_bitmaps("Full GC End");
1084
1085 // At this point there should be no regions in the
1086 // entire heap tagged as young.
1087 assert(check_young_list_empty(), "young list should be empty at this point");
1088
1089 // Note: since we've just done a full GC, concurrent
1090 // marking is no longer active. Therefore we need not
1091 // re-enable reference discovery for the CM ref processor.
1092 // That will be done at the start of the next marking cycle.
1093 // We also know that the STW processor should no longer
1094 // discover any new references.
1095 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1096 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1097 _ref_processor_stw->verify_no_references_recorded();
1098 _ref_processor_cm->verify_no_references_recorded();
1099 }
1100
1101 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1102 // Post collection logging.
1103 // We should do this after we potentially resize the heap so
1104 // that all the COMMIT / UNCOMMIT events are generated before
1105 // the compaction events.
1106 print_hrm_post_compaction();
1107 heap_transition->print();
1108 print_heap_after_gc();
1109 print_heap_regions();
1110 }
1111
1112 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1113 bool clear_all_soft_refs) {
1114 assert_at_safepoint_on_vm_thread();
1115
1116 if (GCLocker::check_active_before_gc()) {
1117 // Full GC was not completed.
1118 return false;
1119 }
1120
1121 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1122 soft_ref_policy()->should_clear_all_soft_refs();
1123
1124 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1125 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1126
1127 collector.prepare_collection();
1128 collector.collect();
1129 collector.complete_collection();
1130
1131 // Full collection was successfully completed.
1132 return true;
1133 }
1134
1135 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1136 // Currently, there is no facility in the do_full_collection(bool) API to notify
1137 // the caller that the collection did not succeed (e.g., because it was locked
1138 // out by the GC locker). So, right now, we'll ignore the return value.
1139 bool dummy = do_full_collection(true, /* explicit_gc */
1140 clear_all_soft_refs);
1141 }
1142
1143 void G1CollectedHeap::resize_heap_if_necessary() {
1144 assert_at_safepoint_on_vm_thread();
1145
1146 // Capacity, free and used after the GC counted as full regions to
1147 // include the waste in the following calculations.
1148 const size_t capacity_after_gc = capacity();
1149 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1150
1151 // This is enforced in arguments.cpp.
1152 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1153 "otherwise the code below doesn't make sense");
1154
1155 // We don't have floating point command-line arguments
1156 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1157 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1158 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1159 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1160
1161 // We have to be careful here as these two calculations can overflow
1162 // 32-bit size_t's.
1163 double used_after_gc_d = (double) used_after_gc;
1164 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1165 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1166
1167 // Let's make sure that they are both under the max heap size, which
1168 // by default will make them fit into a size_t.
1169 double desired_capacity_upper_bound = (double) MaxHeapSize;
1170 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1171 desired_capacity_upper_bound);
1172 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1173 desired_capacity_upper_bound);
1174
1175 // We can now safely turn them into size_t's.
1176 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1177 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1178
1179 // This assert only makes sense here, before we adjust them
1180 // with respect to the min and max heap size.
1181 assert(minimum_desired_capacity <= maximum_desired_capacity,
1182 "minimum_desired_capacity = " SIZE_FORMAT ", "
1183 "maximum_desired_capacity = " SIZE_FORMAT,
1184 minimum_desired_capacity, maximum_desired_capacity);
1185
1186 // Should not be greater than the heap max size. No need to adjust
1187 // it with respect to the heap min size as it's a lower bound (i.e.,
1188 // we'll try to make the capacity larger than it, not smaller).
1189 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1190 // Should not be less than the heap min size. No need to adjust it
1191 // with respect to the heap max size as it's an upper bound (i.e.,
1192 // we'll try to make the capacity smaller than it, not greater).
1193 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1194
1195 if (capacity_after_gc < minimum_desired_capacity) {
1196 // Don't expand unless it's significant
1197 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1198
1199 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1200 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1201 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1202 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1203
1204 expand(expand_bytes, _workers);
1205
1206 // No expansion, now see if we want to shrink
1207 } else if (capacity_after_gc > maximum_desired_capacity) {
1208 // Capacity too large, compute shrinking size
1209 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1210
1211 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1212 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1213 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1214 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1215
1216 shrink(shrink_bytes);
1217 }
1218 }
1219
1220 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1221 bool do_gc,
1222 bool clear_all_soft_refs,
1223 bool expect_null_mutator_alloc_region,
1224 bool* gc_succeeded) {
1225 *gc_succeeded = true;
1226 // Let's attempt the allocation first.
1227 HeapWord* result =
1228 attempt_allocation_at_safepoint(word_size,
1229 expect_null_mutator_alloc_region);
1230 if (result != NULL) {
1231 return result;
1232 }
1233
1234 // In a G1 heap, we're supposed to keep allocation from failing by
1235 // incremental pauses. Therefore, at least for now, we'll favor
1236 // expansion over collection. (This might change in the future if we can
1237 // do something smarter than full collection to satisfy a failed alloc.)
1238 result = expand_and_allocate(word_size);
1239 if (result != NULL) {
1240 return result;
1241 }
1242
1243 if (do_gc) {
1244 // Expansion didn't work, we'll try to do a Full GC.
1245 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1246 clear_all_soft_refs);
1247 }
1248
1249 return NULL;
1250 }
1251
1252 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1253 bool* succeeded) {
1254 assert_at_safepoint_on_vm_thread();
1255
1256 // Attempts to allocate followed by Full GC.
1257 HeapWord* result =
1258 satisfy_failed_allocation_helper(word_size,
1259 true, /* do_gc */
1260 false, /* clear_all_soft_refs */
1261 false, /* expect_null_mutator_alloc_region */
1262 succeeded);
1263
1264 if (result != NULL || !*succeeded) {
1265 return result;
1266 }
1267
1268 // Attempts to allocate followed by Full GC that will collect all soft references.
1269 result = satisfy_failed_allocation_helper(word_size,
1270 true, /* do_gc */
1271 true, /* clear_all_soft_refs */
1272 true, /* expect_null_mutator_alloc_region */
1273 succeeded);
1274
1275 if (result != NULL || !*succeeded) {
1276 return result;
1277 }
1278
1279 // Attempts to allocate, no GC
1280 result = satisfy_failed_allocation_helper(word_size,
1281 false, /* do_gc */
1282 false, /* clear_all_soft_refs */
1283 true, /* expect_null_mutator_alloc_region */
1284 succeeded);
1285
1286 if (result != NULL) {
1287 return result;
1288 }
1289
1290 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1291 "Flag should have been handled and cleared prior to this point");
1292
1293 // What else? We might try synchronous finalization later. If the total
1294 // space available is large enough for the allocation, then a more
1295 // complete compaction phase than we've tried so far might be
1296 // appropriate.
1297 return NULL;
1298 }
1299
1300 // Attempting to expand the heap sufficiently
1301 // to support an allocation of the given "word_size". If
1302 // successful, perform the allocation and return the address of the
1303 // allocated block, or else "NULL".
1304
1305 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1306 assert_at_safepoint_on_vm_thread();
1307
1308 _verifier->verify_region_sets_optional();
1309
1310 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1311 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1312 word_size * HeapWordSize);
1313
1314
1315 if (expand(expand_bytes, _workers)) {
1316 _hrm->verify_optional();
1317 _verifier->verify_region_sets_optional();
1318 return attempt_allocation_at_safepoint(word_size,
1319 false /* expect_null_mutator_alloc_region */);
1320 }
1321 return NULL;
1322 }
1323
1324 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1325 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1326 aligned_expand_bytes = align_up(aligned_expand_bytes,
1327 HeapRegion::GrainBytes);
1328
1329 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1330 expand_bytes, aligned_expand_bytes);
1331
1332 if (is_maximal_no_gc()) {
1333 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1334 return false;
1335 }
1336
1337 double expand_heap_start_time_sec = os::elapsedTime();
1338 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1339 assert(regions_to_expand > 0, "Must expand by at least one region");
1340
1341 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1342 if (expand_time_ms != NULL) {
1343 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1344 }
1345
1346 if (expanded_by > 0) {
1347 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1348 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1349 policy()->record_new_heap_size(num_regions());
1350 } else {
1351 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1352
1353 // The expansion of the virtual storage space was unsuccessful.
1354 // Let's see if it was because we ran out of swap.
1355 if (G1ExitOnExpansionFailure &&
1356 _hrm->available() >= regions_to_expand) {
1357 // We had head room...
1358 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1359 }
1360 }
1361 return regions_to_expand > 0;
1362 }
1363
1364 bool G1CollectedHeap::expand_single_region(uint node_index) {
1365 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1366
1367 if (expanded_by == 0) {
1368 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1369 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1370 return false;
1371 }
1372
1373 policy()->record_new_heap_size(num_regions());
1374 return true;
1375 }
1376
1377 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1378 size_t aligned_shrink_bytes =
1379 ReservedSpace::page_align_size_down(shrink_bytes);
1380 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1381 HeapRegion::GrainBytes);
1382 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1383
1384 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1385 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1386
1387 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B attempted shrinking amount: " SIZE_FORMAT "B",
1388 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1389 if (num_regions_removed > 0) {
1390 policy()->record_new_heap_size(num_regions());
1391 } else {
1392 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1393 }
1394 }
1395
1396 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1397 _verifier->verify_region_sets_optional();
1398
1399 // We should only reach here at the end of a Full GC or during Remark which
1400 // means we should not not be holding to any GC alloc regions. The method
1401 // below will make sure of that and do any remaining clean up.
1402 _allocator->abandon_gc_alloc_regions();
1403
1404 // Instead of tearing down / rebuilding the free lists here, we
1405 // could instead use the remove_all_pending() method on free_list to
1406 // remove only the ones that we need to remove.
1407 tear_down_region_sets(true /* free_list_only */);
1408 shrink_helper(shrink_bytes);
1409 rebuild_region_sets(true /* free_list_only */);
1410
1411 _hrm->verify_optional();
1412 _verifier->verify_region_sets_optional();
1413 }
1414
1415 class OldRegionSetChecker : public HeapRegionSetChecker {
1416 public:
1417 void check_mt_safety() {
1418 // Master Old Set MT safety protocol:
1419 // (a) If we're at a safepoint, operations on the master old set
1420 // should be invoked:
1421 // - by the VM thread (which will serialize them), or
1422 // - by the GC workers while holding the FreeList_lock, if we're
1423 // at a safepoint for an evacuation pause (this lock is taken
1424 // anyway when an GC alloc region is retired so that a new one
1425 // is allocated from the free list), or
1426 // - by the GC workers while holding the OldSets_lock, if we're at a
1427 // safepoint for a cleanup pause.
1428 // (b) If we're not at a safepoint, operations on the master old set
1429 // should be invoked while holding the Heap_lock.
1430
1431 if (SafepointSynchronize::is_at_safepoint()) {
1432 guarantee(Thread::current()->is_VM_thread() ||
1433 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1434 "master old set MT safety protocol at a safepoint");
1435 } else {
1436 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1437 }
1438 }
1439 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1440 const char* get_description() { return "Old Regions"; }
1441 };
1442
1443 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1444 public:
1445 void check_mt_safety() {
1446 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1447 "May only change archive regions during initialization or safepoint.");
1448 }
1449 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1450 const char* get_description() { return "Archive Regions"; }
1451 };
1452
1453 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1454 public:
1455 void check_mt_safety() {
1456 // Humongous Set MT safety protocol:
1457 // (a) If we're at a safepoint, operations on the master humongous
1458 // set should be invoked by either the VM thread (which will
1459 // serialize them) or by the GC workers while holding the
1460 // OldSets_lock.
1461 // (b) If we're not at a safepoint, operations on the master
1462 // humongous set should be invoked while holding the Heap_lock.
1463
1464 if (SafepointSynchronize::is_at_safepoint()) {
1465 guarantee(Thread::current()->is_VM_thread() ||
1466 OldSets_lock->owned_by_self(),
1467 "master humongous set MT safety protocol at a safepoint");
1468 } else {
1469 guarantee(Heap_lock->owned_by_self(),
1470 "master humongous set MT safety protocol outside a safepoint");
1471 }
1472 }
1473 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1474 const char* get_description() { return "Humongous Regions"; }
1475 };
1476
1477 G1CollectedHeap::G1CollectedHeap() :
1478 CollectedHeap(),
1479 _young_gen_sampling_thread(NULL),
1480 _workers(NULL),
1481 _card_table(NULL),
1482 _soft_ref_policy(),
1483 _old_set("Old Region Set", new OldRegionSetChecker()),
1484 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1485 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1486 _bot(NULL),
1487 _listener(),
1488 _numa(G1NUMA::create()),
1489 _hrm(NULL),
1490 _allocator(NULL),
1491 _verifier(NULL),
1492 _summary_bytes_used(0),
1493 _bytes_used_during_gc(0),
1494 _archive_allocator(NULL),
1495 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1496 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1497 _expand_heap_after_alloc_failure(true),
1498 _g1mm(NULL),
1499 _humongous_reclaim_candidates(),
1500 _has_humongous_reclaim_candidates(false),
1501 _hr_printer(),
1502 _collector_state(),
1503 _old_marking_cycles_started(0),
1504 _old_marking_cycles_completed(0),
1505 _eden(),
1506 _survivor(),
1507 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1508 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1509 _policy(G1Policy::create_policy(_gc_timer_stw)),
1510 _heap_sizing_policy(NULL),
1511 _collection_set(this, _policy),
1512 _hot_card_cache(NULL),
1513 _rem_set(NULL),
1514 _cm(NULL),
1515 _cm_thread(NULL),
1516 _cr(NULL),
1517 _task_queues(NULL),
1518 _evacuation_failed(false),
1519 _evacuation_failed_info_array(NULL),
1520 _preserved_marks_set(true /* in_c_heap */),
1521 #ifndef PRODUCT
1522 _evacuation_failure_alot_for_current_gc(false),
1523 _evacuation_failure_alot_gc_number(0),
1524 _evacuation_failure_alot_count(0),
1525 #endif
1526 _ref_processor_stw(NULL),
1527 _is_alive_closure_stw(this),
1528 _is_subject_to_discovery_stw(this),
1529 _ref_processor_cm(NULL),
1530 _is_alive_closure_cm(this),
1531 _is_subject_to_discovery_cm(this),
1532 _region_attr() {
1533
1534 _verifier = new G1HeapVerifier(this);
1535
1536 _allocator = new G1Allocator(this);
1537
1538 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1539
1540 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1541
1542 // Override the default _filler_array_max_size so that no humongous filler
1543 // objects are created.
1544 _filler_array_max_size = _humongous_object_threshold_in_words;
1545
1546 uint n_queues = ParallelGCThreads;
1547 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1548
1549 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1550
1551 for (uint i = 0; i < n_queues; i++) {
1552 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1553 q->initialize();
1554 _task_queues->register_queue(i, q);
1555 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1556 }
1557
1558 // Initialize the G1EvacuationFailureALot counters and flags.
1559 NOT_PRODUCT(reset_evacuation_should_fail();)
1560 _gc_tracer_stw->initialize();
1561
1562 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1563 }
1564
1565 static size_t actual_reserved_page_size(ReservedSpace rs) {
1566 size_t page_size = os::vm_page_size();
1567 if (UseLargePages) {
1568 // There are two ways to manage large page memory.
1569 // 1. OS supports committing large page memory.
1570 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1571 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1572 // we reserved memory without large page.
1573 if (os::can_commit_large_page_memory() || rs.special()) {
1574 // An alignment at ReservedSpace comes from preferred page size or
1575 // heap alignment, and if the alignment came from heap alignment, it could be
1576 // larger than large pages size. So need to cap with the large page size.
1577 page_size = MIN2(rs.alignment(), os::large_page_size());
1578 }
1579 }
1580
1581 return page_size;
1582 }
1583
1584 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1585 size_t size,
1586 size_t translation_factor) {
1587 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1588 // Allocate a new reserved space, preferring to use large pages.
1589 ReservedSpace rs(size, preferred_page_size);
1590 size_t page_size = actual_reserved_page_size(rs);
1591 G1RegionToSpaceMapper* result =
1592 G1RegionToSpaceMapper::create_mapper(rs,
1593 size,
1594 page_size,
1595 HeapRegion::GrainBytes,
1596 translation_factor,
1597 mtGC);
1598
1599 os::trace_page_sizes_for_requested_size(description,
1600 size,
1601 preferred_page_size,
1602 page_size,
1603 rs.base(),
1604 rs.size());
1605
1606 return result;
1607 }
1608
1609 jint G1CollectedHeap::initialize_concurrent_refinement() {
1610 jint ecode = JNI_OK;
1611 _cr = G1ConcurrentRefine::create(&ecode);
1612 return ecode;
1613 }
1614
1615 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1616 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1617 if (_young_gen_sampling_thread->osthread() == NULL) {
1618 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1619 return JNI_ENOMEM;
1620 }
1621 return JNI_OK;
1622 }
1623
1624 jint G1CollectedHeap::initialize() {
1625
1626 // Necessary to satisfy locking discipline assertions.
1627
1628 MutexLocker x(Heap_lock);
1629
1630 // While there are no constraints in the GC code that HeapWordSize
1631 // be any particular value, there are multiple other areas in the
1632 // system which believe this to be true (e.g. oop->object_size in some
1633 // cases incorrectly returns the size in wordSize units rather than
1634 // HeapWordSize).
1635 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1636
1637 size_t init_byte_size = InitialHeapSize;
1638 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1639
1640 // Ensure that the sizes are properly aligned.
1641 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1642 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1643 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1644
1645 // Reserve the maximum.
1646
1647 // When compressed oops are enabled, the preferred heap base
1648 // is calculated by subtracting the requested size from the
1649 // 32Gb boundary and using the result as the base address for
1650 // heap reservation. If the requested size is not aligned to
1651 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1652 // into the ReservedHeapSpace constructor) then the actual
1653 // base of the reserved heap may end up differing from the
1654 // address that was requested (i.e. the preferred heap base).
1655 // If this happens then we could end up using a non-optimal
1656 // compressed oops mode.
1657
1658 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1659 HeapAlignment);
1660
1661 initialize_reserved_region(heap_rs);
1662
1663 // Create the barrier set for the entire reserved region.
1664 G1CardTable* ct = new G1CardTable(heap_rs.region());
1665 ct->initialize();
1666 G1BarrierSet* bs = new G1BarrierSet(ct);
1667 bs->initialize();
1668 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1669 BarrierSet::set_barrier_set(bs);
1670 _card_table = ct;
1671
1672 {
1673 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1674 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1675 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1676 }
1677
1678 // Create the hot card cache.
1679 _hot_card_cache = new G1HotCardCache(this);
1680
1681 // Carve out the G1 part of the heap.
1682 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1683 size_t page_size = actual_reserved_page_size(heap_rs);
1684 G1RegionToSpaceMapper* heap_storage =
1685 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1686 g1_rs.size(),
1687 page_size,
1688 HeapRegion::GrainBytes,
1689 1,
1690 mtJavaHeap);
1691 if(heap_storage == NULL) {
1692 vm_shutdown_during_initialization("Could not initialize G1 heap");
1693 return JNI_ERR;
1694 }
1695
1696 os::trace_page_sizes("Heap",
1697 MinHeapSize,
1698 reserved_byte_size,
1699 page_size,
1700 heap_rs.base(),
1701 heap_rs.size());
1702 heap_storage->set_mapping_changed_listener(&_listener);
1703
1704 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1705 G1RegionToSpaceMapper* bot_storage =
1706 create_aux_memory_mapper("Block Offset Table",
1707 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1708 G1BlockOffsetTable::heap_map_factor());
1709
1710 G1RegionToSpaceMapper* cardtable_storage =
1711 create_aux_memory_mapper("Card Table",
1712 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1713 G1CardTable::heap_map_factor());
1714
1715 G1RegionToSpaceMapper* card_counts_storage =
1716 create_aux_memory_mapper("Card Counts Table",
1717 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1718 G1CardCounts::heap_map_factor());
1719
1720 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1721 G1RegionToSpaceMapper* prev_bitmap_storage =
1722 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1723 G1RegionToSpaceMapper* next_bitmap_storage =
1724 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1725
1726 _hrm = HeapRegionManager::create_manager(this);
1727
1728 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1729 _card_table->initialize(cardtable_storage);
1730
1731 // Do later initialization work for concurrent refinement.
1732 _hot_card_cache->initialize(card_counts_storage);
1733
1734 // 6843694 - ensure that the maximum region index can fit
1735 // in the remembered set structures.
1736 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1737 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1738
1739 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1740 // start within the first card.
1741 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1742 // Also create a G1 rem set.
1743 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1744 _rem_set->initialize(max_reserved_capacity(), max_regions());
1745
1746 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1747 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1748 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1749 "too many cards per region");
1750
1751 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1752
1753 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1754
1755 {
1756 HeapWord* start = _hrm->reserved().start();
1757 HeapWord* end = _hrm->reserved().end();
1758 size_t granularity = HeapRegion::GrainBytes;
1759
1760 _region_attr.initialize(start, end, granularity);
1761 _humongous_reclaim_candidates.initialize(start, end, granularity);
1762 }
1763
1764 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1765 true /* are_GC_task_threads */,
1766 false /* are_ConcurrentGC_threads */);
1767 if (_workers == NULL) {
1768 return JNI_ENOMEM;
1769 }
1770 _workers->initialize_workers();
1771
1772 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1773
1774 // Create the G1ConcurrentMark data structure and thread.
1775 // (Must do this late, so that "max_regions" is defined.)
1776 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1777 _cm_thread = _cm->cm_thread();
1778
1779 // Now expand into the initial heap size.
1780 if (!expand(init_byte_size, _workers)) {
1781 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1782 return JNI_ENOMEM;
1783 }
1784
1785 // Perform any initialization actions delegated to the policy.
1786 policy()->init(this, &_collection_set);
1787
1788 jint ecode = initialize_concurrent_refinement();
1789 if (ecode != JNI_OK) {
1790 return ecode;
1791 }
1792
1793 ecode = initialize_young_gen_sampling_thread();
1794 if (ecode != JNI_OK) {
1795 return ecode;
1796 }
1797
1798 {
1799 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1800 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1801 dcqs.set_max_cards(concurrent_refine()->red_zone());
1802 }
1803
1804 // Here we allocate the dummy HeapRegion that is required by the
1805 // G1AllocRegion class.
1806 HeapRegion* dummy_region = _hrm->get_dummy_region();
1807
1808 // We'll re-use the same region whether the alloc region will
1809 // require BOT updates or not and, if it doesn't, then a non-young
1810 // region will complain that it cannot support allocations without
1811 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1812 dummy_region->set_eden();
1813 // Make sure it's full.
1814 dummy_region->set_top(dummy_region->end());
1815 G1AllocRegion::setup(this, dummy_region);
1816
1817 _allocator->init_mutator_alloc_regions();
1818
1819 // Do create of the monitoring and management support so that
1820 // values in the heap have been properly initialized.
1821 _g1mm = new G1MonitoringSupport(this);
1822
1823 G1StringDedup::initialize();
1824
1825 _preserved_marks_set.init(ParallelGCThreads);
1826
1827 _collection_set.initialize(max_regions());
1828
1829 G1InitLogger::print();
1830
1831 return JNI_OK;
1832 }
1833
1834 void G1CollectedHeap::stop() {
1835 // Stop all concurrent threads. We do this to make sure these threads
1836 // do not continue to execute and access resources (e.g. logging)
1837 // that are destroyed during shutdown.
1838 _cr->stop();
1839 _young_gen_sampling_thread->stop();
1840 _cm_thread->stop();
1841 if (G1StringDedup::is_enabled()) {
1842 G1StringDedup::stop();
1843 }
1844 }
1845
1846 void G1CollectedHeap::safepoint_synchronize_begin() {
1847 SuspendibleThreadSet::synchronize();
1848 }
1849
1850 void G1CollectedHeap::safepoint_synchronize_end() {
1851 SuspendibleThreadSet::desynchronize();
1852 }
1853
1854 void G1CollectedHeap::post_initialize() {
1855 CollectedHeap::post_initialize();
1856 ref_processing_init();
1857 }
1858
1859 void G1CollectedHeap::ref_processing_init() {
1860 // Reference processing in G1 currently works as follows:
1861 //
1862 // * There are two reference processor instances. One is
1863 // used to record and process discovered references
1864 // during concurrent marking; the other is used to
1865 // record and process references during STW pauses
1866 // (both full and incremental).
1867 // * Both ref processors need to 'span' the entire heap as
1868 // the regions in the collection set may be dotted around.
1869 //
1870 // * For the concurrent marking ref processor:
1871 // * Reference discovery is enabled at initial marking.
1872 // * Reference discovery is disabled and the discovered
1873 // references processed etc during remarking.
1874 // * Reference discovery is MT (see below).
1875 // * Reference discovery requires a barrier (see below).
1876 // * Reference processing may or may not be MT
1877 // (depending on the value of ParallelRefProcEnabled
1878 // and ParallelGCThreads).
1879 // * A full GC disables reference discovery by the CM
1880 // ref processor and abandons any entries on it's
1881 // discovered lists.
1882 //
1883 // * For the STW processor:
1884 // * Non MT discovery is enabled at the start of a full GC.
1885 // * Processing and enqueueing during a full GC is non-MT.
1886 // * During a full GC, references are processed after marking.
1887 //
1888 // * Discovery (may or may not be MT) is enabled at the start
1889 // of an incremental evacuation pause.
1890 // * References are processed near the end of a STW evacuation pause.
1891 // * For both types of GC:
1892 // * Discovery is atomic - i.e. not concurrent.
1893 // * Reference discovery will not need a barrier.
1894
1895 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1896
1897 // Concurrent Mark ref processor
1898 _ref_processor_cm =
1899 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1900 mt_processing, // mt processing
1901 ParallelGCThreads, // degree of mt processing
1902 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1903 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1904 false, // Reference discovery is not atomic
1905 &_is_alive_closure_cm, // is alive closure
1906 true); // allow changes to number of processing threads
1907
1908 // STW ref processor
1909 _ref_processor_stw =
1910 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1911 mt_processing, // mt processing
1912 ParallelGCThreads, // degree of mt processing
1913 (ParallelGCThreads > 1), // mt discovery
1914 ParallelGCThreads, // degree of mt discovery
1915 true, // Reference discovery is atomic
1916 &_is_alive_closure_stw, // is alive closure
1917 true); // allow changes to number of processing threads
1918 }
1919
1920 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1921 return &_soft_ref_policy;
1922 }
1923
1924 size_t G1CollectedHeap::capacity() const {
1925 return _hrm->length() * HeapRegion::GrainBytes;
1926 }
1927
1928 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1929 return _hrm->total_free_bytes();
1930 }
1931
1932 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1933 _hot_card_cache->drain(cl, worker_id);
1934 }
1935
1936 // Computes the sum of the storage used by the various regions.
1937 size_t G1CollectedHeap::used() const {
1938 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1939 if (_archive_allocator != NULL) {
1940 result += _archive_allocator->used();
1941 }
1942 return result;
1943 }
1944
1945 size_t G1CollectedHeap::used_unlocked() const {
1946 return _summary_bytes_used;
1947 }
1948
1949 class SumUsedClosure: public HeapRegionClosure {
1950 size_t _used;
1951 public:
1952 SumUsedClosure() : _used(0) {}
1953 bool do_heap_region(HeapRegion* r) {
1954 _used += r->used();
1955 return false;
1956 }
1957 size_t result() { return _used; }
1958 };
1959
1960 size_t G1CollectedHeap::recalculate_used() const {
1961 SumUsedClosure blk;
1962 heap_region_iterate(&blk);
1963 return blk.result();
1964 }
1965
1966 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1967 switch (cause) {
1968 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1969 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1970 case GCCause::_wb_conc_mark: return true;
1971 default : return false;
1972 }
1973 }
1974
1975 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1976 switch (cause) {
1977 case GCCause::_g1_humongous_allocation: return true;
1978 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1979 case GCCause::_wb_breakpoint: return true;
1980 default: return is_user_requested_concurrent_full_gc(cause);
1981 }
1982 }
1983
1984 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1985 if (policy()->force_upgrade_to_full()) {
1986 return true;
1987 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1988 return false;
1989 } else if (has_regions_left_for_allocation()) {
1990 return false;
1991 } else {
1992 return true;
1993 }
1994 }
1995
1996 #ifndef PRODUCT
1997 void G1CollectedHeap::allocate_dummy_regions() {
1998 // Let's fill up most of the region
1999 size_t word_size = HeapRegion::GrainWords - 1024;
2000 // And as a result the region we'll allocate will be humongous.
2001 guarantee(is_humongous(word_size), "sanity");
2002
2003 // _filler_array_max_size is set to humongous object threshold
2004 // but temporarily change it to use CollectedHeap::fill_with_object().
2005 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2006
2007 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2008 // Let's use the existing mechanism for the allocation
2009 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2010 if (dummy_obj != NULL) {
2011 MemRegion mr(dummy_obj, word_size);
2012 CollectedHeap::fill_with_object(mr);
2013 } else {
2014 // If we can't allocate once, we probably cannot allocate
2015 // again. Let's get out of the loop.
2016 break;
2017 }
2018 }
2019 }
2020 #endif // !PRODUCT
2021
2022 void G1CollectedHeap::increment_old_marking_cycles_started() {
2023 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2024 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2025 "Wrong marking cycle count (started: %d, completed: %d)",
2026 _old_marking_cycles_started, _old_marking_cycles_completed);
2027
2028 _old_marking_cycles_started++;
2029 }
2030
2031 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2032 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2033
2034 // We assume that if concurrent == true, then the caller is a
2035 // concurrent thread that was joined the Suspendible Thread
2036 // Set. If there's ever a cheap way to check this, we should add an
2037 // assert here.
2038
2039 // Given that this method is called at the end of a Full GC or of a
2040 // concurrent cycle, and those can be nested (i.e., a Full GC can
2041 // interrupt a concurrent cycle), the number of full collections
2042 // completed should be either one (in the case where there was no
2043 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2044 // behind the number of full collections started.
2045
2046 // This is the case for the inner caller, i.e. a Full GC.
2047 assert(concurrent ||
2048 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2049 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2050 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2051 "is inconsistent with _old_marking_cycles_completed = %u",
2052 _old_marking_cycles_started, _old_marking_cycles_completed);
2053
2054 // This is the case for the outer caller, i.e. the concurrent cycle.
2055 assert(!concurrent ||
2056 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2057 "for outer caller (concurrent cycle): "
2058 "_old_marking_cycles_started = %u "
2059 "is inconsistent with _old_marking_cycles_completed = %u",
2060 _old_marking_cycles_started, _old_marking_cycles_completed);
2061
2062 _old_marking_cycles_completed += 1;
2063
2064 // We need to clear the "in_progress" flag in the CM thread before
2065 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2066 // is set) so that if a waiter requests another System.gc() it doesn't
2067 // incorrectly see that a marking cycle is still in progress.
2068 if (concurrent) {
2069 _cm_thread->set_idle();
2070 }
2071
2072 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2073 // for a full GC to finish that their wait is over.
2074 ml.notify_all();
2075 }
2076
2077 void G1CollectedHeap::collect(GCCause::Cause cause) {
2078 try_collect(cause);
2079 }
2080
2081 // Return true if (x < y) with allowance for wraparound.
2082 static bool gc_counter_less_than(uint x, uint y) {
2083 return (x - y) > (UINT_MAX/2);
2084 }
2085
2086 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2087 // Macro so msg printing is format-checked.
2088 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2089 do { \
2090 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2091 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2092 ResourceMark rm; /* For thread name. */ \
2093 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2094 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2095 Thread::current()->name(), \
2096 GCCause::to_string(cause)); \
2097 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2098 } \
2099 } while (0)
2100
2101 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2102 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2103
2104 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2105 uint gc_counter,
2106 uint old_marking_started_before) {
2107 assert_heap_not_locked();
2108 assert(should_do_concurrent_full_gc(cause),
2109 "Non-concurrent cause %s", GCCause::to_string(cause));
2110
2111 for (uint i = 1; true; ++i) {
2112 // Try to schedule an initial-mark evacuation pause that will
2113 // start a concurrent cycle.
2114 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2115 VM_G1TryInitiateConcMark op(gc_counter,
2116 cause,
2117 policy()->max_pause_time_ms());
2118 VMThread::execute(&op);
2119
2120 // Request is trivially finished.
2121 if (cause == GCCause::_g1_periodic_collection) {
2122 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2123 return op.gc_succeeded();
2124 }
2125
2126 // If VMOp skipped initiating concurrent marking cycle because
2127 // we're terminating, then we're done.
2128 if (op.terminating()) {
2129 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2130 return false;
2131 }
2132
2133 // Lock to get consistent set of values.
2134 uint old_marking_started_after;
2135 uint old_marking_completed_after;
2136 {
2137 MutexLocker ml(Heap_lock);
2138 // Update gc_counter for retrying VMOp if needed. Captured here to be
2139 // consistent with the values we use below for termination tests. If
2140 // a retry is needed after a possible wait, and another collection
2141 // occurs in the meantime, it will cause our retry to be skipped and
2142 // we'll recheck for termination with updated conditions from that
2143 // more recent collection. That's what we want, rather than having
2144 // our retry possibly perform an unnecessary collection.
2145 gc_counter = total_collections();
2146 old_marking_started_after = _old_marking_cycles_started;
2147 old_marking_completed_after = _old_marking_cycles_completed;
2148 }
2149
2150 if (cause == GCCause::_wb_breakpoint) {
2151 if (op.gc_succeeded()) {
2152 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2153 return true;
2154 }
2155 // When _wb_breakpoint there can't be another cycle or deferred.
2156 assert(!op.cycle_already_in_progress(), "invariant");
2157 assert(!op.whitebox_attached(), "invariant");
2158 // Concurrent cycle attempt might have been cancelled by some other
2159 // collection, so retry. Unlike other cases below, we want to retry
2160 // even if cancelled by a STW full collection, because we really want
2161 // to start a concurrent cycle.
2162 if (old_marking_started_before != old_marking_started_after) {
2163 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2164 old_marking_started_before = old_marking_started_after;
2165 }
2166 } else if (!GCCause::is_user_requested_gc(cause)) {
2167 // For an "automatic" (not user-requested) collection, we just need to
2168 // ensure that progress is made.
2169 //
2170 // Request is finished if any of
2171 // (1) the VMOp successfully performed a GC,
2172 // (2) a concurrent cycle was already in progress,
2173 // (3) whitebox is controlling concurrent cycles,
2174 // (4) a new cycle was started (by this thread or some other), or
2175 // (5) a Full GC was performed.
2176 // Cases (4) and (5) are detected together by a change to
2177 // _old_marking_cycles_started.
2178 //
2179 // Note that (1) does not imply (4). If we're still in the mixed
2180 // phase of an earlier concurrent collection, the request to make the
2181 // collection an initial-mark won't be honored. If we don't check for
2182 // both conditions we'll spin doing back-to-back collections.
2183 if (op.gc_succeeded() ||
2184 op.cycle_already_in_progress() ||
2185 op.whitebox_attached() ||
2186 (old_marking_started_before != old_marking_started_after)) {
2187 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2188 return true;
2189 }
2190 } else { // User-requested GC.
2191 // For a user-requested collection, we want to ensure that a complete
2192 // full collection has been performed before returning, but without
2193 // waiting for more than needed.
2194
2195 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2196 // new cycle was started. That's good, because it's not clear what we
2197 // should do otherwise. Trying again just does back to back GCs.
2198 // Can't wait for someone else to start a cycle. And returning fails
2199 // to meet the goal of ensuring a full collection was performed.
2200 assert(!op.gc_succeeded() ||
2201 (old_marking_started_before != old_marking_started_after),
2202 "invariant: succeeded %s, started before %u, started after %u",
2203 BOOL_TO_STR(op.gc_succeeded()),
2204 old_marking_started_before, old_marking_started_after);
2205
2206 // Request is finished if a full collection (concurrent or stw)
2207 // was started after this request and has completed, e.g.
2208 // started_before < completed_after.
2209 if (gc_counter_less_than(old_marking_started_before,
2210 old_marking_completed_after)) {
2211 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2212 return true;
2213 }
2214
2215 if (old_marking_started_after != old_marking_completed_after) {
2216 // If there is an in-progress cycle (possibly started by us), then
2217 // wait for that cycle to complete, e.g.
2218 // while completed_now < started_after.
2219 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2220 MonitorLocker ml(G1OldGCCount_lock);
2221 while (gc_counter_less_than(_old_marking_cycles_completed,
2222 old_marking_started_after)) {
2223 ml.wait();
2224 }
2225 // Request is finished if the collection we just waited for was
2226 // started after this request.
2227 if (old_marking_started_before != old_marking_started_after) {
2228 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2229 return true;
2230 }
2231 }
2232
2233 // If VMOp was successful then it started a new cycle that the above
2234 // wait &etc should have recognized as finishing this request. This
2235 // differs from a non-user-request, where gc_succeeded does not imply
2236 // a new cycle was started.
2237 assert(!op.gc_succeeded(), "invariant");
2238
2239 if (op.cycle_already_in_progress()) {
2240 // If VMOp failed because a cycle was already in progress, it
2241 // is now complete. But it didn't finish this user-requested
2242 // GC, so try again.
2243 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2244 continue;
2245 } else if (op.whitebox_attached()) {
2246 // If WhiteBox wants control, wait for notification of a state
2247 // change in the controller, then try again. Don't wait for
2248 // release of control, since collections may complete while in
2249 // control. Note: This won't recognize a STW full collection
2250 // while waiting; we can't wait on multiple monitors.
2251 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2252 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2253 if (ConcurrentGCBreakpoints::is_controlled()) {
2254 ml.wait();
2255 }
2256 continue;
2257 }
2258 }
2259
2260 // Collection failed and should be retried.
2261 assert(op.transient_failure(), "invariant");
2262
2263 if (GCLocker::is_active_and_needs_gc()) {
2264 // If GCLocker is active, wait until clear before retrying.
2265 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2266 GCLocker::stall_until_clear();
2267 }
2268
2269 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2270 }
2271 }
2272
2273 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2274 assert_heap_not_locked();
2275
2276 // Lock to get consistent set of values.
2277 uint gc_count_before;
2278 uint full_gc_count_before;
2279 uint old_marking_started_before;
2280 {
2281 MutexLocker ml(Heap_lock);
2282 gc_count_before = total_collections();
2283 full_gc_count_before = total_full_collections();
2284 old_marking_started_before = _old_marking_cycles_started;
2285 }
2286
2287 if (should_do_concurrent_full_gc(cause)) {
2288 return try_collect_concurrently(cause,
2289 gc_count_before,
2290 old_marking_started_before);
2291 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2292 // Indicate failure to be consistent with VMOp failure due to
2293 // another collection slipping in after our gc_count but before
2294 // our request is processed.
2295 return false;
2296 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2297 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2298
2299 // Schedule a standard evacuation pause. We're setting word_size
2300 // to 0 which means that we are not requesting a post-GC allocation.
2301 VM_G1CollectForAllocation op(0, /* word_size */
2302 gc_count_before,
2303 cause,
2304 policy()->max_pause_time_ms());
2305 VMThread::execute(&op);
2306 return op.gc_succeeded();
2307 } else {
2308 // Schedule a Full GC.
2309 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2310 VMThread::execute(&op);
2311 return op.gc_succeeded();
2312 }
2313 }
2314
2315 bool G1CollectedHeap::is_in(const void* p) const {
2316 if (_hrm->reserved().contains(p)) {
2317 // Given that we know that p is in the reserved space,
2318 // heap_region_containing() should successfully
2319 // return the containing region.
2320 HeapRegion* hr = heap_region_containing(p);
2321 return hr->is_in(p);
2322 } else {
2323 return false;
2324 }
2325 }
2326
2327 #ifdef ASSERT
2328 bool G1CollectedHeap::is_in_exact(const void* p) const {
2329 bool contains = reserved_region().contains(p);
2330 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2331 if (contains && available) {
2332 return true;
2333 } else {
2334 return false;
2335 }
2336 }
2337 #endif
2338
2339 // Iteration functions.
2340
2341 // Iterates an ObjectClosure over all objects within a HeapRegion.
2342
2343 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2344 ObjectClosure* _cl;
2345 public:
2346 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2347 bool do_heap_region(HeapRegion* r) {
2348 if (!r->is_continues_humongous()) {
2349 r->object_iterate(_cl);
2350 }
2351 return false;
2352 }
2353 };
2354
2355 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2356 IterateObjectClosureRegionClosure blk(cl);
2357 heap_region_iterate(&blk);
2358 }
2359
2360 void G1CollectedHeap::keep_alive(oop obj) {
2361 G1BarrierSet::enqueue(obj);
2362 }
2363
2364 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2365 _hrm->iterate(cl);
2366 }
2367
2368 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2369 HeapRegionClaimer *hrclaimer,
2370 uint worker_id) const {
2371 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2372 }
2373
2374 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2375 HeapRegionClaimer *hrclaimer) const {
2376 _hrm->par_iterate(cl, hrclaimer, 0);
2377 }
2378
2379 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2380 _collection_set.iterate(cl);
2381 }
2382
2383 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2384 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2385 }
2386
2387 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2388 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2389 }
2390
2391 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2392 HeapRegion* hr = heap_region_containing(addr);
2393 return hr->block_start(addr);
2394 }
2395
2396 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2397 HeapRegion* hr = heap_region_containing(addr);
2398 return hr->block_is_obj(addr);
2399 }
2400
2401 bool G1CollectedHeap::supports_tlab_allocation() const {
2402 return true;
2403 }
2404
2405 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2406 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2407 }
2408
2409 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2410 return _eden.length() * HeapRegion::GrainBytes;
2411 }
2412
2413 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2414 // must be equal to the humongous object limit.
2415 size_t G1CollectedHeap::max_tlab_size() const {
2416 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2417 }
2418
2419 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2420 return _allocator->unsafe_max_tlab_alloc();
2421 }
2422
2423 size_t G1CollectedHeap::max_capacity() const {
2424 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2425 }
2426
2427 size_t G1CollectedHeap::max_reserved_capacity() const {
2428 return _hrm->max_length() * HeapRegion::GrainBytes;
2429 }
2430
2431 jlong G1CollectedHeap::millis_since_last_gc() {
2432 // See the notes in GenCollectedHeap::millis_since_last_gc()
2433 // for more information about the implementation.
2434 jlong ret_val = (os::javaTimeNanos() - _policy->time_of_last_gc()) /
2435 NANOSECS_PER_MILLISEC;
2436 if (ret_val < 0) {
2437 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
2438 return 0;
2439 }
2440 return ret_val;
2441 }
2442
2443 void G1CollectedHeap::deduplicate_string(oop str) {
2444 assert(java_lang_String::is_instance(str), "invariant");
2445
2446 if (G1StringDedup::is_enabled()) {
2447 G1StringDedup::deduplicate(str);
2448 }
2449 }
2450
2451 void G1CollectedHeap::prepare_for_verify() {
2452 _verifier->prepare_for_verify();
2453 }
2454
2455 void G1CollectedHeap::verify(VerifyOption vo) {
2456 _verifier->verify(vo);
2457 }
2458
2459 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2460 return true;
2461 }
2462
2463 bool G1CollectedHeap::is_heterogeneous_heap() const {
2464 return G1Arguments::is_heterogeneous_heap();
2465 }
2466
2467 class PrintRegionClosure: public HeapRegionClosure {
2468 outputStream* _st;
2469 public:
2470 PrintRegionClosure(outputStream* st) : _st(st) {}
2471 bool do_heap_region(HeapRegion* r) {
2472 r->print_on(_st);
2473 return false;
2474 }
2475 };
2476
2477 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2478 const HeapRegion* hr,
2479 const VerifyOption vo) const {
2480 switch (vo) {
2481 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2482 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2483 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2484 default: ShouldNotReachHere();
2485 }
2486 return false; // keep some compilers happy
2487 }
2488
2489 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2490 const VerifyOption vo) const {
2491 switch (vo) {
2492 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2493 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2494 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2495 default: ShouldNotReachHere();
2496 }
2497 return false; // keep some compilers happy
2498 }
2499
2500 void G1CollectedHeap::print_heap_regions() const {
2501 LogTarget(Trace, gc, heap, region) lt;
2502 if (lt.is_enabled()) {
2503 LogStream ls(lt);
2504 print_regions_on(&ls);
2505 }
2506 }
2507
2508 void G1CollectedHeap::print_on(outputStream* st) const {
2509 st->print(" %-20s", "garbage-first heap");
2510 if (_hrm != NULL) {
2511 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2512 capacity()/K, used_unlocked()/K);
2513 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2514 p2i(_hrm->reserved().start()),
2515 p2i(_hrm->reserved().end()));
2516 }
2517 st->cr();
2518 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2519 uint young_regions = young_regions_count();
2520 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2521 (size_t) young_regions * HeapRegion::GrainBytes / K);
2522 uint survivor_regions = survivor_regions_count();
2523 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2524 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2525 st->cr();
2526 if (_numa->is_enabled()) {
2527 uint num_nodes = _numa->num_active_nodes();
2528 st->print(" remaining free region(s) on each NUMA node: ");
2529 const int* node_ids = _numa->node_ids();
2530 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2531 uint num_free_regions = (_hrm != NULL ? _hrm->num_free_regions(node_index) : 0);
2532 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2533 }
2534 st->cr();
2535 }
2536 MetaspaceUtils::print_on(st);
2537 }
2538
2539 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2540 if (_hrm == NULL) {
2541 return;
2542 }
2543
2544 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2545 "HS=humongous(starts), HC=humongous(continues), "
2546 "CS=collection set, F=free, "
2547 "OA=open archive, CA=closed archive, "
2548 "TAMS=top-at-mark-start (previous, next)");
2549 PrintRegionClosure blk(st);
2550 heap_region_iterate(&blk);
2551 }
2552
2553 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2554 print_on(st);
2555
2556 // Print the per-region information.
2557 if (_hrm != NULL) {
2558 st->cr();
2559 print_regions_on(st);
2560 }
2561 }
2562
2563 void G1CollectedHeap::print_on_error(outputStream* st) const {
2564 this->CollectedHeap::print_on_error(st);
2565
2566 if (_cm != NULL) {
2567 st->cr();
2568 _cm->print_on_error(st);
2569 }
2570 }
2571
2572 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2573 workers()->threads_do(tc);
2574 tc->do_thread(_cm_thread);
2575 _cm->threads_do(tc);
2576 _cr->threads_do(tc);
2577 tc->do_thread(_young_gen_sampling_thread);
2578 if (G1StringDedup::is_enabled()) {
2579 G1StringDedup::threads_do(tc);
2580 }
2581 }
2582
2583 void G1CollectedHeap::print_tracing_info() const {
2584 rem_set()->print_summary_info();
2585 concurrent_mark()->print_summary_info();
2586 }
2587
2588 #ifndef PRODUCT
2589 // Helpful for debugging RSet issues.
2590
2591 class PrintRSetsClosure : public HeapRegionClosure {
2592 private:
2593 const char* _msg;
2594 size_t _occupied_sum;
2595
2596 public:
2597 bool do_heap_region(HeapRegion* r) {
2598 HeapRegionRemSet* hrrs = r->rem_set();
2599 size_t occupied = hrrs->occupied();
2600 _occupied_sum += occupied;
2601
2602 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2603 if (occupied == 0) {
2604 tty->print_cr(" RSet is empty");
2605 } else {
2606 hrrs->print();
2607 }
2608 tty->print_cr("----------");
2609 return false;
2610 }
2611
2612 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2613 tty->cr();
2614 tty->print_cr("========================================");
2615 tty->print_cr("%s", msg);
2616 tty->cr();
2617 }
2618
2619 ~PrintRSetsClosure() {
2620 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2621 tty->print_cr("========================================");
2622 tty->cr();
2623 }
2624 };
2625
2626 void G1CollectedHeap::print_cset_rsets() {
2627 PrintRSetsClosure cl("Printing CSet RSets");
2628 collection_set_iterate_all(&cl);
2629 }
2630
2631 void G1CollectedHeap::print_all_rsets() {
2632 PrintRSetsClosure cl("Printing All RSets");;
2633 heap_region_iterate(&cl);
2634 }
2635 #endif // PRODUCT
2636
2637 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2638 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2639 }
2640
2641 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2642
2643 size_t eden_used_bytes = _eden.used_bytes();
2644 size_t survivor_used_bytes = _survivor.used_bytes();
2645 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2646
2647 size_t eden_capacity_bytes =
2648 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2649
2650 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2651 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2652 eden_capacity_bytes, survivor_used_bytes, num_regions());
2653 }
2654
2655 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2656 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2657 stats->unused(), stats->used(), stats->region_end_waste(),
2658 stats->regions_filled(), stats->direct_allocated(),
2659 stats->failure_used(), stats->failure_waste());
2660 }
2661
2662 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2663 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2664 gc_tracer->report_gc_heap_summary(when, heap_summary);
2665
2666 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2667 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2668 }
2669
2670 void G1CollectedHeap::gc_prologue(bool full) {
2671 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2672
2673 // This summary needs to be printed before incrementing total collections.
2674 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2675
2676 // Update common counters.
2677 increment_total_collections(full /* full gc */);
2678 if (full || collector_state()->in_initial_mark_gc()) {
2679 increment_old_marking_cycles_started();
2680 }
2681
2682 // Fill TLAB's and such
2683 {
2684 Ticks start = Ticks::now();
2685 ensure_parsability(true);
2686 Tickspan dt = Ticks::now() - start;
2687 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2688 }
2689
2690 if (!full) {
2691 // Flush dirty card queues to qset, so later phases don't need to account
2692 // for partially filled per-thread queues and such. Not needed for full
2693 // collections, which ignore those logs.
2694 Ticks start = Ticks::now();
2695 G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2696 Tickspan dt = Ticks::now() - start;
2697 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2698 }
2699 }
2700
2701 void G1CollectedHeap::gc_epilogue(bool full) {
2702 // Update common counters.
2703 if (full) {
2704 // Update the number of full collections that have been completed.
2705 increment_old_marking_cycles_completed(false /* concurrent */);
2706 }
2707
2708 // We are at the end of the GC. Total collections has already been increased.
2709 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2710
2711 // FIXME: what is this about?
2712 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2713 // is set.
2714 #if COMPILER2_OR_JVMCI
2715 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2716 #endif
2717
2718 double start = os::elapsedTime();
2719 resize_all_tlabs();
2720 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2721
2722 MemoryService::track_memory_usage();
2723 // We have just completed a GC. Update the soft reference
2724 // policy with the new heap occupancy
2725 Universe::update_heap_info_at_gc();
2726
2727 // Print NUMA statistics.
2728 _numa->print_statistics();
2729 }
2730
2731 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2732 LogTarget(Trace, gc, heap, verify) lt;
2733
2734 if (lt.is_enabled()) {
2735 LogStream ls(lt);
2736 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2737 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2738 heap_region_iterate(&cl);
2739 }
2740 }
2741
2742 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2743 uint gc_count_before,
2744 bool* succeeded,
2745 GCCause::Cause gc_cause) {
2746 assert_heap_not_locked_and_not_at_safepoint();
2747 VM_G1CollectForAllocation op(word_size,
2748 gc_count_before,
2749 gc_cause,
2750 policy()->max_pause_time_ms());
2751 VMThread::execute(&op);
2752
2753 HeapWord* result = op.result();
2754 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2755 assert(result == NULL || ret_succeeded,
2756 "the result should be NULL if the VM did not succeed");
2757 *succeeded = ret_succeeded;
2758
2759 assert_heap_not_locked();
2760 return result;
2761 }
2762
2763 void G1CollectedHeap::do_concurrent_mark() {
2764 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2765 if (!_cm_thread->in_progress()) {
2766 _cm_thread->set_started();
2767 CGC_lock->notify();
2768 }
2769 }
2770
2771 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2772 // We don't nominate objects with many remembered set entries, on
2773 // the assumption that such objects are likely still live.
2774 HeapRegionRemSet* rem_set = r->rem_set();
2775
2776 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2777 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2778 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2779 }
2780
2781 #ifndef PRODUCT
2782 void G1CollectedHeap::verify_region_attr_remset_update() {
2783 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2784 public:
2785 virtual bool do_heap_region(HeapRegion* r) {
2786 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2787 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2788 assert(r->rem_set()->is_tracked() == needs_remset_update,
2789 "Region %u remset tracking status (%s) different to region attribute (%s)",
2790 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2791 return false;
2792 }
2793 } cl;
2794 heap_region_iterate(&cl);
2795 }
2796 #endif
2797
2798 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2799 public:
2800 bool do_heap_region(HeapRegion* hr) {
2801 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2802 hr->verify_rem_set();
2803 }
2804 return false;
2805 }
2806 };
2807
2808 uint G1CollectedHeap::num_task_queues() const {
2809 return _task_queues->size();
2810 }
2811
2812 #if TASKQUEUE_STATS
2813 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2814 st->print_raw_cr("GC Task Stats");
2815 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2816 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2817 }
2818
2819 void G1CollectedHeap::print_taskqueue_stats() const {
2820 if (!log_is_enabled(Trace, gc, task, stats)) {
2821 return;
2822 }
2823 Log(gc, task, stats) log;
2824 ResourceMark rm;
2825 LogStream ls(log.trace());
2826 outputStream* st = &ls;
2827
2828 print_taskqueue_stats_hdr(st);
2829
2830 TaskQueueStats totals;
2831 const uint n = num_task_queues();
2832 for (uint i = 0; i < n; ++i) {
2833 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2834 totals += task_queue(i)->stats;
2835 }
2836 st->print_raw("tot "); totals.print(st); st->cr();
2837
2838 DEBUG_ONLY(totals.verify());
2839 }
2840
2841 void G1CollectedHeap::reset_taskqueue_stats() {
2842 const uint n = num_task_queues();
2843 for (uint i = 0; i < n; ++i) {
2844 task_queue(i)->stats.reset();
2845 }
2846 }
2847 #endif // TASKQUEUE_STATS
2848
2849 void G1CollectedHeap::wait_for_root_region_scanning() {
2850 double scan_wait_start = os::elapsedTime();
2851 // We have to wait until the CM threads finish scanning the
2852 // root regions as it's the only way to ensure that all the
2853 // objects on them have been correctly scanned before we start
2854 // moving them during the GC.
2855 bool waited = _cm->root_regions()->wait_until_scan_finished();
2856 double wait_time_ms = 0.0;
2857 if (waited) {
2858 double scan_wait_end = os::elapsedTime();
2859 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2860 }
2861 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2862 }
2863
2864 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2865 private:
2866 G1HRPrinter* _hr_printer;
2867 public:
2868 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2869
2870 virtual bool do_heap_region(HeapRegion* r) {
2871 _hr_printer->cset(r);
2872 return false;
2873 }
2874 };
2875
2876 void G1CollectedHeap::start_new_collection_set() {
2877 double start = os::elapsedTime();
2878
2879 collection_set()->start_incremental_building();
2880
2881 clear_region_attr();
2882
2883 guarantee(_eden.length() == 0, "eden should have been cleared");
2884 policy()->transfer_survivors_to_cset(survivor());
2885
2886 // We redo the verification but now wrt to the new CSet which
2887 // has just got initialized after the previous CSet was freed.
2888 _cm->verify_no_collection_set_oops();
2889
2890 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2891 }
2892
2893 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2894
2895 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2896 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2897 collection_set()->optional_region_length());
2898
2899 _cm->verify_no_collection_set_oops();
2900
2901 if (_hr_printer.is_active()) {
2902 G1PrintCollectionSetClosure cl(&_hr_printer);
2903 _collection_set.iterate(&cl);
2904 _collection_set.iterate_optional(&cl);
2905 }
2906 }
2907
2908 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2909 if (collector_state()->in_initial_mark_gc()) {
2910 return G1HeapVerifier::G1VerifyConcurrentStart;
2911 } else if (collector_state()->in_young_only_phase()) {
2912 return G1HeapVerifier::G1VerifyYoungNormal;
2913 } else {
2914 return G1HeapVerifier::G1VerifyMixed;
2915 }
2916 }
2917
2918 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2919 if (VerifyRememberedSets) {
2920 log_info(gc, verify)("[Verifying RemSets before GC]");
2921 VerifyRegionRemSetClosure v_cl;
2922 heap_region_iterate(&v_cl);
2923 }
2924 _verifier->verify_before_gc(type);
2925 _verifier->check_bitmaps("GC Start");
2926 verify_numa_regions("GC Start");
2927 }
2928
2929 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2930 if (VerifyRememberedSets) {
2931 log_info(gc, verify)("[Verifying RemSets after GC]");
2932 VerifyRegionRemSetClosure v_cl;
2933 heap_region_iterate(&v_cl);
2934 }
2935 _verifier->verify_after_gc(type);
2936 _verifier->check_bitmaps("GC End");
2937 verify_numa_regions("GC End");
2938 }
2939
2940 void G1CollectedHeap::expand_heap_after_young_collection(){
2941 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2942 if (expand_bytes > 0) {
2943 // No need for an ergo logging here,
2944 // expansion_amount() does this when it returns a value > 0.
2945 double expand_ms;
2946 if (!expand(expand_bytes, _workers, &expand_ms)) {
2947 // We failed to expand the heap. Cannot do anything about it.
2948 }
2949 phase_times()->record_expand_heap_time(expand_ms);
2950 }
2951 }
2952
2953 const char* G1CollectedHeap::young_gc_name() const {
2954 if (collector_state()->in_initial_mark_gc()) {
2955 return "Pause Young (Concurrent Start)";
2956 } else if (collector_state()->in_young_only_phase()) {
2957 if (collector_state()->in_young_gc_before_mixed()) {
2958 return "Pause Young (Prepare Mixed)";
2959 } else {
2960 return "Pause Young (Normal)";
2961 }
2962 } else {
2963 return "Pause Young (Mixed)";
2964 }
2965 }
2966
2967 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2968 assert_at_safepoint_on_vm_thread();
2969 guarantee(!is_gc_active(), "collection is not reentrant");
2970
2971 if (GCLocker::check_active_before_gc()) {
2972 return false;
2973 }
2974
2975 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2976 if (should_upgrade_to_full_gc(gc_cause())) {
2977 log_info(gc, ergo)("Attempting maximally compacting collection");
2978 bool result = do_full_collection(false /* explicit gc */,
2979 true /* clear_all_soft_refs */);
2980 // do_full_collection only fails if blocked by GC locker, but
2981 // we've already checked for that above.
2982 assert(result, "invariant");
2983 }
2984 return true;
2985 }
2986
2987 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2988 GCIdMark gc_id_mark;
2989
2990 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2991 ResourceMark rm;
2992
2993 policy()->note_gc_start();
2994
2995 _gc_timer_stw->register_gc_start();
2996 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2997
2998 wait_for_root_region_scanning();
2999
3000 print_heap_before_gc();
3001 print_heap_regions();
3002 trace_heap_before_gc(_gc_tracer_stw);
3003
3004 _verifier->verify_region_sets_optional();
3005 _verifier->verify_dirty_young_regions();
3006
3007 // We should not be doing initial mark unless the conc mark thread is running
3008 if (!_cm_thread->should_terminate()) {
3009 // This call will decide whether this pause is an initial-mark
3010 // pause. If it is, in_initial_mark_gc() will return true
3011 // for the duration of this pause.
3012 policy()->decide_on_conc_mark_initiation();
3013 }
3014
3015 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3016 assert(!collector_state()->in_initial_mark_gc() ||
3017 collector_state()->in_young_only_phase(), "sanity");
3018 // We also do not allow mixed GCs during marking.
3019 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3020
3021 // Record whether this pause is an initial mark. When the current
3022 // thread has completed its logging output and it's safe to signal
3023 // the CM thread, the flag's value in the policy has been reset.
3024 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3025 if (should_start_conc_mark) {
3026 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3027 }
3028
3029 // Inner scope for scope based logging, timers, and stats collection
3030 {
3031 G1EvacuationInfo evacuation_info;
3032
3033 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3034
3035 GCTraceCPUTime tcpu;
3036
3037 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3038
3039 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3040 workers()->active_workers(),
3041 Threads::number_of_non_daemon_threads());
3042 active_workers = workers()->update_active_workers(active_workers);
3043 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3044
3045 G1MonitoringScope ms(g1mm(),
3046 false /* full_gc */,
3047 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3048
3049 G1HeapTransition heap_transition(this);
3050
3051 {
3052 IsGCActiveMark x;
3053
3054 gc_prologue(false);
3055
3056 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3057 verify_before_young_collection(verify_type);
3058
3059 {
3060 // The elapsed time induced by the start time below deliberately elides
3061 // the possible verification above.
3062 double sample_start_time_sec = os::elapsedTime();
3063
3064 // Please see comment in g1CollectedHeap.hpp and
3065 // G1CollectedHeap::ref_processing_init() to see how
3066 // reference processing currently works in G1.
3067 _ref_processor_stw->enable_discovery();
3068
3069 // We want to temporarily turn off discovery by the
3070 // CM ref processor, if necessary, and turn it back on
3071 // on again later if we do. Using a scoped
3072 // NoRefDiscovery object will do this.
3073 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3074
3075 policy()->record_collection_pause_start(sample_start_time_sec);
3076
3077 // Forget the current allocation region (we might even choose it to be part
3078 // of the collection set!).
3079 _allocator->release_mutator_alloc_regions();
3080
3081 calculate_collection_set(evacuation_info, target_pause_time_ms);
3082
3083 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3084 G1ParScanThreadStateSet per_thread_states(this,
3085 &rdcqs,
3086 workers()->active_workers(),
3087 collection_set()->young_region_length(),
3088 collection_set()->optional_region_length());
3089 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3090
3091 // Actually do the work...
3092 evacuate_initial_collection_set(&per_thread_states);
3093
3094 if (_collection_set.optional_region_length() != 0) {
3095 evacuate_optional_collection_set(&per_thread_states);
3096 }
3097 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3098
3099 start_new_collection_set();
3100
3101 _survivor_evac_stats.adjust_desired_plab_sz();
3102 _old_evac_stats.adjust_desired_plab_sz();
3103
3104 if (should_start_conc_mark) {
3105 // We have to do this before we notify the CM threads that
3106 // they can start working to make sure that all the
3107 // appropriate initialization is done on the CM object.
3108 concurrent_mark()->post_initial_mark();
3109 // Note that we don't actually trigger the CM thread at
3110 // this point. We do that later when we're sure that
3111 // the current thread has completed its logging output.
3112 }
3113
3114 allocate_dummy_regions();
3115
3116 _allocator->init_mutator_alloc_regions();
3117
3118 expand_heap_after_young_collection();
3119
3120 double sample_end_time_sec = os::elapsedTime();
3121 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3122 policy()->record_collection_pause_end(pause_time_ms);
3123 }
3124
3125 verify_after_young_collection(verify_type);
3126
3127 gc_epilogue(false);
3128 }
3129
3130 // Print the remainder of the GC log output.
3131 if (evacuation_failed()) {
3132 log_info(gc)("To-space exhausted");
3133 }
3134
3135 policy()->print_phases();
3136 heap_transition.print();
3137
3138 _hrm->verify_optional();
3139 _verifier->verify_region_sets_optional();
3140
3141 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3142 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3143
3144 print_heap_after_gc();
3145 print_heap_regions();
3146 trace_heap_after_gc(_gc_tracer_stw);
3147
3148 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3149 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3150 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3151 // before any GC notifications are raised.
3152 g1mm()->update_sizes();
3153
3154 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3155 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3156 _gc_timer_stw->register_gc_end();
3157 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3158 }
3159 // It should now be safe to tell the concurrent mark thread to start
3160 // without its logging output interfering with the logging output
3161 // that came from the pause.
3162
3163 if (should_start_conc_mark) {
3164 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3165 // thread(s) could be running concurrently with us. Make sure that anything
3166 // after this point does not assume that we are the only GC thread running.
3167 // Note: of course, the actual marking work will not start until the safepoint
3168 // itself is released in SuspendibleThreadSet::desynchronize().
3169 do_concurrent_mark();
3170 ConcurrentGCBreakpoints::notify_idle_to_active();
3171 }
3172 }
3173
3174 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3175 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3176 workers()->run_task(&rsfp_task);
3177 }
3178
3179 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3180 double remove_self_forwards_start = os::elapsedTime();
3181
3182 remove_self_forwarding_pointers(rdcqs);
3183 _preserved_marks_set.restore(workers());
3184
3185 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3186 }
3187
3188 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3189 if (!_evacuation_failed) {
3190 _evacuation_failed = true;
3191 }
3192
3193 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3194 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3195 }
3196
3197 bool G1ParEvacuateFollowersClosure::offer_termination() {
3198 EventGCPhaseParallel event;
3199 G1ParScanThreadState* const pss = par_scan_state();
3200 start_term_time();
3201 const bool res = terminator()->offer_termination();
3202 end_term_time();
3203 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3204 return res;
3205 }
3206
3207 void G1ParEvacuateFollowersClosure::do_void() {
3208 EventGCPhaseParallel event;
3209 G1ParScanThreadState* const pss = par_scan_state();
3210 pss->trim_queue();
3211 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3212 do {
3213 EventGCPhaseParallel event;
3214 pss->steal_and_trim_queue(queues());
3215 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3216 } while (!offer_termination());
3217 }
3218
3219 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3220 bool class_unloading_occurred) {
3221 uint num_workers = workers()->active_workers();
3222 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3223 workers()->run_task(&unlink_task);
3224 }
3225
3226 // Clean string dedup data structures.
3227 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3228 // record the durations of the phases. Hence the almost-copy.
3229 class G1StringDedupCleaningTask : public AbstractGangTask {
3230 BoolObjectClosure* _is_alive;
3231 OopClosure* _keep_alive;
3232 G1GCPhaseTimes* _phase_times;
3233
3234 public:
3235 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3236 OopClosure* keep_alive,
3237 G1GCPhaseTimes* phase_times) :
3238 AbstractGangTask("Partial Cleaning Task"),
3239 _is_alive(is_alive),
3240 _keep_alive(keep_alive),
3241 _phase_times(phase_times)
3242 {
3243 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3244 StringDedup::gc_prologue(true);
3245 }
3246
3247 ~G1StringDedupCleaningTask() {
3248 StringDedup::gc_epilogue();
3249 }
3250
3251 void work(uint worker_id) {
3252 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3253 {
3254 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3255 StringDedupQueue::unlink_or_oops_do(&cl);
3256 }
3257 {
3258 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3259 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3260 }
3261 }
3262 };
3263
3264 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3265 OopClosure* keep_alive,
3266 G1GCPhaseTimes* phase_times) {
3267 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3268 workers()->run_task(&cl);
3269 }
3270
3271 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3272 private:
3273 G1RedirtyCardsQueueSet* _qset;
3274 G1CollectedHeap* _g1h;
3275 BufferNode* volatile _nodes;
3276
3277 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3278 size_t buffer_size = _qset->buffer_size();
3279 BufferNode* next = Atomic::load(&_nodes);
3280 while (next != NULL) {
3281 BufferNode* node = next;
3282 next = Atomic::cmpxchg(&_nodes, node, node->next());
3283 if (next == node) {
3284 cl->apply_to_buffer(node, buffer_size, worker_id);
3285 next = node->next();
3286 }
3287 }
3288 }
3289
3290 public:
3291 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3292 AbstractGangTask("Redirty Cards"),
3293 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3294
3295 virtual void work(uint worker_id) {
3296 G1GCPhaseTimes* p = _g1h->phase_times();
3297 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3298
3299 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3300 par_apply(&cl, worker_id);
3301
3302 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3303 }
3304 };
3305
3306 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3307 double redirty_logged_cards_start = os::elapsedTime();
3308
3309 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3310 workers()->run_task(&redirty_task);
3311
3312 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3313 dcq.merge_bufferlists(rdcqs);
3314
3315 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3316 }
3317
3318 // Weak Reference Processing support
3319
3320 bool G1STWIsAliveClosure::do_object_b(oop p) {
3321 // An object is reachable if it is outside the collection set,
3322 // or is inside and copied.
3323 return !_g1h->is_in_cset(p) || p->is_forwarded();
3324 }
3325
3326 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3327 assert(obj != NULL, "must not be NULL");
3328 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3329 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3330 // may falsely indicate that this is not the case here: however the collection set only
3331 // contains old regions when concurrent mark is not running.
3332 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3333 }
3334
3335 // Non Copying Keep Alive closure
3336 class G1KeepAliveClosure: public OopClosure {
3337 G1CollectedHeap*_g1h;
3338 public:
3339 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3340 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3341 void do_oop(oop* p) {
3342 oop obj = *p;
3343 assert(obj != NULL, "the caller should have filtered out NULL values");
3344
3345 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3346 if (!region_attr.is_in_cset_or_humongous()) {
3347 return;
3348 }
3349 if (region_attr.is_in_cset()) {
3350 assert( obj->is_forwarded(), "invariant" );
3351 *p = obj->forwardee();
3352 } else {
3353 assert(!obj->is_forwarded(), "invariant" );
3354 assert(region_attr.is_humongous(),
3355 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3356 _g1h->set_humongous_is_live(obj);
3357 }
3358 }
3359 };
3360
3361 // Copying Keep Alive closure - can be called from both
3362 // serial and parallel code as long as different worker
3363 // threads utilize different G1ParScanThreadState instances
3364 // and different queues.
3365
3366 class G1CopyingKeepAliveClosure: public OopClosure {
3367 G1CollectedHeap* _g1h;
3368 G1ParScanThreadState* _par_scan_state;
3369
3370 public:
3371 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3372 G1ParScanThreadState* pss):
3373 _g1h(g1h),
3374 _par_scan_state(pss)
3375 {}
3376
3377 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3378 virtual void do_oop( oop* p) { do_oop_work(p); }
3379
3380 template <class T> void do_oop_work(T* p) {
3381 oop obj = RawAccess<>::oop_load(p);
3382
3383 if (_g1h->is_in_cset_or_humongous(obj)) {
3384 // If the referent object has been forwarded (either copied
3385 // to a new location or to itself in the event of an
3386 // evacuation failure) then we need to update the reference
3387 // field and, if both reference and referent are in the G1
3388 // heap, update the RSet for the referent.
3389 //
3390 // If the referent has not been forwarded then we have to keep
3391 // it alive by policy. Therefore we have copy the referent.
3392 //
3393 // When the queue is drained (after each phase of reference processing)
3394 // the object and it's followers will be copied, the reference field set
3395 // to point to the new location, and the RSet updated.
3396 _par_scan_state->push_on_queue(ScannerTask(p));
3397 }
3398 }
3399 };
3400
3401 // Serial drain queue closure. Called as the 'complete_gc'
3402 // closure for each discovered list in some of the
3403 // reference processing phases.
3404
3405 class G1STWDrainQueueClosure: public VoidClosure {
3406 protected:
3407 G1CollectedHeap* _g1h;
3408 G1ParScanThreadState* _par_scan_state;
3409
3410 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3411
3412 public:
3413 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3414 _g1h(g1h),
3415 _par_scan_state(pss)
3416 { }
3417
3418 void do_void() {
3419 G1ParScanThreadState* const pss = par_scan_state();
3420 pss->trim_queue();
3421 }
3422 };
3423
3424 // Parallel Reference Processing closures
3425
3426 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3427 // processing during G1 evacuation pauses.
3428
3429 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3430 private:
3431 G1CollectedHeap* _g1h;
3432 G1ParScanThreadStateSet* _pss;
3433 G1ScannerTasksQueueSet* _queues;
3434 WorkGang* _workers;
3435
3436 public:
3437 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3438 G1ParScanThreadStateSet* per_thread_states,
3439 WorkGang* workers,
3440 G1ScannerTasksQueueSet *task_queues) :
3441 _g1h(g1h),
3442 _pss(per_thread_states),
3443 _queues(task_queues),
3444 _workers(workers)
3445 {
3446 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3447 }
3448
3449 // Executes the given task using concurrent marking worker threads.
3450 virtual void execute(ProcessTask& task, uint ergo_workers);
3451 };
3452
3453 // Gang task for possibly parallel reference processing
3454
3455 class G1STWRefProcTaskProxy: public AbstractGangTask {
3456 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3457 ProcessTask& _proc_task;
3458 G1CollectedHeap* _g1h;
3459 G1ParScanThreadStateSet* _pss;
3460 G1ScannerTasksQueueSet* _task_queues;
3461 TaskTerminator* _terminator;
3462
3463 public:
3464 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3465 G1CollectedHeap* g1h,
3466 G1ParScanThreadStateSet* per_thread_states,
3467 G1ScannerTasksQueueSet *task_queues,
3468 TaskTerminator* terminator) :
3469 AbstractGangTask("Process reference objects in parallel"),
3470 _proc_task(proc_task),
3471 _g1h(g1h),
3472 _pss(per_thread_states),
3473 _task_queues(task_queues),
3474 _terminator(terminator)
3475 {}
3476
3477 virtual void work(uint worker_id) {
3478 // The reference processing task executed by a single worker.
3479 ResourceMark rm;
3480 HandleMark hm;
3481
3482 G1STWIsAliveClosure is_alive(_g1h);
3483
3484 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3485 pss->set_ref_discoverer(NULL);
3486
3487 // Keep alive closure.
3488 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3489
3490 // Complete GC closure
3491 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3492
3493 // Call the reference processing task's work routine.
3494 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3495
3496 // Note we cannot assert that the refs array is empty here as not all
3497 // of the processing tasks (specifically phase2 - pp2_work) execute
3498 // the complete_gc closure (which ordinarily would drain the queue) so
3499 // the queue may not be empty.
3500 }
3501 };
3502
3503 // Driver routine for parallel reference processing.
3504 // Creates an instance of the ref processing gang
3505 // task and has the worker threads execute it.
3506 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3507 assert(_workers != NULL, "Need parallel worker threads.");
3508
3509 assert(_workers->active_workers() >= ergo_workers,
3510 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3511 ergo_workers, _workers->active_workers());
3512 TaskTerminator terminator(ergo_workers, _queues);
3513 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3514
3515 _workers->run_task(&proc_task_proxy, ergo_workers);
3516 }
3517
3518 // End of weak reference support closures
3519
3520 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3521 double ref_proc_start = os::elapsedTime();
3522
3523 ReferenceProcessor* rp = _ref_processor_stw;
3524 assert(rp->discovery_enabled(), "should have been enabled");
3525
3526 // Closure to test whether a referent is alive.
3527 G1STWIsAliveClosure is_alive(this);
3528
3529 // Even when parallel reference processing is enabled, the processing
3530 // of JNI refs is serial and performed serially by the current thread
3531 // rather than by a worker. The following PSS will be used for processing
3532 // JNI refs.
3533
3534 // Use only a single queue for this PSS.
3535 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3536 pss->set_ref_discoverer(NULL);
3537 assert(pss->queue_is_empty(), "pre-condition");
3538
3539 // Keep alive closure.
3540 G1CopyingKeepAliveClosure keep_alive(this, pss);
3541
3542 // Serial Complete GC closure
3543 G1STWDrainQueueClosure drain_queue(this, pss);
3544
3545 // Setup the soft refs policy...
3546 rp->setup_policy(false);
3547
3548 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3549
3550 ReferenceProcessorStats stats;
3551 if (!rp->processing_is_mt()) {
3552 // Serial reference processing...
3553 stats = rp->process_discovered_references(&is_alive,
3554 &keep_alive,
3555 &drain_queue,
3556 NULL,
3557 pt);
3558 } else {
3559 uint no_of_gc_workers = workers()->active_workers();
3560
3561 // Parallel reference processing
3562 assert(no_of_gc_workers <= rp->max_num_queues(),
3563 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3564 no_of_gc_workers, rp->max_num_queues());
3565
3566 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3567 stats = rp->process_discovered_references(&is_alive,
3568 &keep_alive,
3569 &drain_queue,
3570 &par_task_executor,
3571 pt);
3572 }
3573
3574 _gc_tracer_stw->report_gc_reference_stats(stats);
3575
3576 // We have completed copying any necessary live referent objects.
3577 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3578
3579 make_pending_list_reachable();
3580
3581 assert(!rp->discovery_enabled(), "Postcondition");
3582 rp->verify_no_references_recorded();
3583
3584 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3585 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3586 }
3587
3588 void G1CollectedHeap::make_pending_list_reachable() {
3589 if (collector_state()->in_initial_mark_gc()) {
3590 oop pll_head = Universe::reference_pending_list();
3591 if (pll_head != NULL) {
3592 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3593 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3594 }
3595 }
3596 }
3597
3598 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3599 Ticks start = Ticks::now();
3600 per_thread_states->flush();
3601 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3602 }
3603
3604 class G1PrepareEvacuationTask : public AbstractGangTask {
3605 class G1PrepareRegionsClosure : public HeapRegionClosure {
3606 G1CollectedHeap* _g1h;
3607 G1PrepareEvacuationTask* _parent_task;
3608 size_t _worker_humongous_total;
3609 size_t _worker_humongous_candidates;
3610
3611 bool humongous_region_is_candidate(HeapRegion* region) const {
3612 assert(region->is_starts_humongous(), "Must start a humongous object");
3613
3614 oop obj = oop(region->bottom());
3615
3616 // Dead objects cannot be eager reclaim candidates. Due to class
3617 // unloading it is unsafe to query their classes so we return early.
3618 if (_g1h->is_obj_dead(obj, region)) {
3619 return false;
3620 }
3621
3622 // If we do not have a complete remembered set for the region, then we can
3623 // not be sure that we have all references to it.
3624 if (!region->rem_set()->is_complete()) {
3625 return false;
3626 }
3627 // Candidate selection must satisfy the following constraints
3628 // while concurrent marking is in progress:
3629 //
3630 // * In order to maintain SATB invariants, an object must not be
3631 // reclaimed if it was allocated before the start of marking and
3632 // has not had its references scanned. Such an object must have
3633 // its references (including type metadata) scanned to ensure no
3634 // live objects are missed by the marking process. Objects
3635 // allocated after the start of concurrent marking don't need to
3636 // be scanned.
3637 //
3638 // * An object must not be reclaimed if it is on the concurrent
3639 // mark stack. Objects allocated after the start of concurrent
3640 // marking are never pushed on the mark stack.
3641 //
3642 // Nominating only objects allocated after the start of concurrent
3643 // marking is sufficient to meet both constraints. This may miss
3644 // some objects that satisfy the constraints, but the marking data
3645 // structures don't support efficiently performing the needed
3646 // additional tests or scrubbing of the mark stack.
3647 //
3648 // However, we presently only nominate is_typeArray() objects.
3649 // A humongous object containing references induces remembered
3650 // set entries on other regions. In order to reclaim such an
3651 // object, those remembered sets would need to be cleaned up.
3652 //
3653 // We also treat is_typeArray() objects specially, allowing them
3654 // to be reclaimed even if allocated before the start of
3655 // concurrent mark. For this we rely on mark stack insertion to
3656 // exclude is_typeArray() objects, preventing reclaiming an object
3657 // that is in the mark stack. We also rely on the metadata for
3658 // such objects to be built-in and so ensured to be kept live.
3659 // Frequent allocation and drop of large binary blobs is an
3660 // important use case for eager reclaim, and this special handling
3661 // may reduce needed headroom.
3662
3663 return obj->is_typeArray() &&
3664 _g1h->is_potential_eager_reclaim_candidate(region);
3665 }
3666
3667 public:
3668 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3669 _g1h(g1h),
3670 _parent_task(parent_task),
3671 _worker_humongous_total(0),
3672 _worker_humongous_candidates(0) { }
3673
3674 ~G1PrepareRegionsClosure() {
3675 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3676 _parent_task->add_humongous_total(_worker_humongous_total);
3677 }
3678
3679 virtual bool do_heap_region(HeapRegion* hr) {
3680 // First prepare the region for scanning
3681 _g1h->rem_set()->prepare_region_for_scan(hr);
3682
3683 // Now check if region is a humongous candidate
3684 if (!hr->is_starts_humongous()) {
3685 _g1h->register_region_with_region_attr(hr);
3686 return false;
3687 }
3688
3689 uint index = hr->hrm_index();
3690 if (humongous_region_is_candidate(hr)) {
3691 _g1h->set_humongous_reclaim_candidate(index, true);
3692 _g1h->register_humongous_region_with_region_attr(index);
3693 _worker_humongous_candidates++;
3694 // We will later handle the remembered sets of these regions.
3695 } else {
3696 _g1h->set_humongous_reclaim_candidate(index, false);
3697 _g1h->register_region_with_region_attr(hr);
3698 }
3699 _worker_humongous_total++;
3700
3701 return false;
3702 }
3703 };
3704
3705 G1CollectedHeap* _g1h;
3706 HeapRegionClaimer _claimer;
3707 volatile size_t _humongous_total;
3708 volatile size_t _humongous_candidates;
3709 public:
3710 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3711 AbstractGangTask("Prepare Evacuation"),
3712 _g1h(g1h),
3713 _claimer(_g1h->workers()->active_workers()),
3714 _humongous_total(0),
3715 _humongous_candidates(0) { }
3716
3717 ~G1PrepareEvacuationTask() {
3718 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3719 }
3720
3721 void work(uint worker_id) {
3722 G1PrepareRegionsClosure cl(_g1h, this);
3723 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3724 }
3725
3726 void add_humongous_candidates(size_t candidates) {
3727 Atomic::add(&_humongous_candidates, candidates);
3728 }
3729
3730 void add_humongous_total(size_t total) {
3731 Atomic::add(&_humongous_total, total);
3732 }
3733
3734 size_t humongous_candidates() {
3735 return _humongous_candidates;
3736 }
3737
3738 size_t humongous_total() {
3739 return _humongous_total;
3740 }
3741 };
3742
3743 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3744 _bytes_used_during_gc = 0;
3745
3746 _expand_heap_after_alloc_failure = true;
3747 _evacuation_failed = false;
3748
3749 // Disable the hot card cache.
3750 _hot_card_cache->reset_hot_cache_claimed_index();
3751 _hot_card_cache->set_use_cache(false);
3752
3753 // Initialize the GC alloc regions.
3754 _allocator->init_gc_alloc_regions(evacuation_info);
3755
3756 {
3757 Ticks start = Ticks::now();
3758 rem_set()->prepare_for_scan_heap_roots();
3759 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3760 }
3761
3762 {
3763 G1PrepareEvacuationTask g1_prep_task(this);
3764 Tickspan task_time = run_task(&g1_prep_task);
3765
3766 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3767 g1_prep_task.humongous_total(),
3768 g1_prep_task.humongous_candidates());
3769 }
3770
3771 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3772 _preserved_marks_set.assert_empty();
3773
3774 #if COMPILER2_OR_JVMCI
3775 DerivedPointerTable::clear();
3776 #endif
3777
3778 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3779 if (collector_state()->in_initial_mark_gc()) {
3780 concurrent_mark()->pre_initial_mark();
3781
3782 double start_clear_claimed_marks = os::elapsedTime();
3783
3784 ClassLoaderDataGraph::clear_claimed_marks();
3785
3786 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3787 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3788 }
3789
3790 // Should G1EvacuationFailureALot be in effect for this GC?
3791 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3792 }
3793
3794 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3795 protected:
3796 G1CollectedHeap* _g1h;
3797 G1ParScanThreadStateSet* _per_thread_states;
3798 G1ScannerTasksQueueSet* _task_queues;
3799 TaskTerminator _terminator;
3800 uint _num_workers;
3801
3802 void evacuate_live_objects(G1ParScanThreadState* pss,
3803 uint worker_id,
3804 G1GCPhaseTimes::GCParPhases objcopy_phase,
3805 G1GCPhaseTimes::GCParPhases termination_phase) {
3806 G1GCPhaseTimes* p = _g1h->phase_times();
3807
3808 Ticks start = Ticks::now();
3809 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3810 cl.do_void();
3811
3812 assert(pss->queue_is_empty(), "should be empty");
3813
3814 Tickspan evac_time = (Ticks::now() - start);
3815 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3816
3817 if (termination_phase == G1GCPhaseTimes::Termination) {
3818 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3819 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3820 } else {
3821 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3822 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3823 }
3824 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3825 }
3826
3827 virtual void start_work(uint worker_id) { }
3828
3829 virtual void end_work(uint worker_id) { }
3830
3831 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3832
3833 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3834
3835 public:
3836 G1EvacuateRegionsBaseTask(const char* name,
3837 G1ParScanThreadStateSet* per_thread_states,
3838 G1ScannerTasksQueueSet* task_queues,
3839 uint num_workers) :
3840 AbstractGangTask(name),
3841 _g1h(G1CollectedHeap::heap()),
3842 _per_thread_states(per_thread_states),
3843 _task_queues(task_queues),
3844 _terminator(num_workers, _task_queues),
3845 _num_workers(num_workers)
3846 { }
3847
3848 void work(uint worker_id) {
3849 start_work(worker_id);
3850
3851 {
3852 ResourceMark rm;
3853 HandleMark hm;
3854
3855 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3856 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3857
3858 scan_roots(pss, worker_id);
3859 evacuate_live_objects(pss, worker_id);
3860 }
3861
3862 end_work(worker_id);
3863 }
3864 };
3865
3866 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3867 G1RootProcessor* _root_processor;
3868
3869 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3870 _root_processor->evacuate_roots(pss, worker_id);
3871 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3872 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3873 }
3874
3875 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3876 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3877 }
3878
3879 void start_work(uint worker_id) {
3880 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3881 }
3882
3883 void end_work(uint worker_id) {
3884 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3885 }
3886
3887 public:
3888 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3889 G1ParScanThreadStateSet* per_thread_states,
3890 G1ScannerTasksQueueSet* task_queues,
3891 G1RootProcessor* root_processor,
3892 uint num_workers) :
3893 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3894 _root_processor(root_processor)
3895 { }
3896 };
3897
3898 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3899 G1GCPhaseTimes* p = phase_times();
3900
3901 {
3902 Ticks start = Ticks::now();
3903 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3904 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3905 }
3906
3907 Tickspan task_time;
3908 const uint num_workers = workers()->active_workers();
3909
3910 Ticks start_processing = Ticks::now();
3911 {
3912 G1RootProcessor root_processor(this, num_workers);
3913 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3914 task_time = run_task(&g1_par_task);
3915 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3916 // To extract its code root fixup time we measure total time of this scope and
3917 // subtract from the time the WorkGang task took.
3918 }
3919 Tickspan total_processing = Ticks::now() - start_processing;
3920
3921 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3922 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3923 }
3924
3925 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3926
3927 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3928 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3929 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3930 }
3931
3932 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3933 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3934 }
3935
3936 public:
3937 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3938 G1ScannerTasksQueueSet* queues,
3939 uint num_workers) :
3940 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3941 }
3942 };
3943
3944 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3945 class G1MarkScope : public MarkScope { };
3946
3947 Tickspan task_time;
3948
3949 Ticks start_processing = Ticks::now();
3950 {
3951 G1MarkScope code_mark_scope;
3952 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3953 task_time = run_task(&task);
3954 // See comment in evacuate_collection_set() for the reason of the scope.
3955 }
3956 Tickspan total_processing = Ticks::now() - start_processing;
3957
3958 G1GCPhaseTimes* p = phase_times();
3959 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3960 }
3961
3962 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3963 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3964
3965 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3966
3967 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3968 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3969
3970 if (time_left_ms < 0 ||
3971 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3972 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3973 _collection_set.optional_region_length(), time_left_ms);
3974 break;
3975 }
3976
3977 {
3978 Ticks start = Ticks::now();
3979 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3980 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3981 }
3982
3983 {
3984 Ticks start = Ticks::now();
3985 evacuate_next_optional_regions(per_thread_states);
3986 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3987 }
3988 }
3989
3990 _collection_set.abandon_optional_collection_set(per_thread_states);
3991 }
3992
3993 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3994 G1RedirtyCardsQueueSet* rdcqs,
3995 G1ParScanThreadStateSet* per_thread_states) {
3996 G1GCPhaseTimes* p = phase_times();
3997
3998 rem_set()->cleanup_after_scan_heap_roots();
3999
4000 // Process any discovered reference objects - we have
4001 // to do this _before_ we retire the GC alloc regions
4002 // as we may have to copy some 'reachable' referent
4003 // objects (and their reachable sub-graphs) that were
4004 // not copied during the pause.
4005 process_discovered_references(per_thread_states);
4006
4007 G1STWIsAliveClosure is_alive(this);
4008 G1KeepAliveClosure keep_alive(this);
4009
4010 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4011
4012 if (G1StringDedup::is_enabled()) {
4013 double string_dedup_time_ms = os::elapsedTime();
4014
4015 string_dedup_cleaning(&is_alive, &keep_alive, p);
4016
4017 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4018 p->record_string_deduplication_time(string_cleanup_time_ms);
4019 }
4020
4021 _allocator->release_gc_alloc_regions(evacuation_info);
4022
4023 if (evacuation_failed()) {
4024 restore_after_evac_failure(rdcqs);
4025
4026 // Reset the G1EvacuationFailureALot counters and flags
4027 NOT_PRODUCT(reset_evacuation_should_fail();)
4028
4029 double recalculate_used_start = os::elapsedTime();
4030 set_used(recalculate_used());
4031 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4032
4033 if (_archive_allocator != NULL) {
4034 _archive_allocator->clear_used();
4035 }
4036 for (uint i = 0; i < ParallelGCThreads; i++) {
4037 if (_evacuation_failed_info_array[i].has_failed()) {
4038 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4039 }
4040 }
4041 } else {
4042 // The "used" of the the collection set have already been subtracted
4043 // when they were freed. Add in the bytes used.
4044 increase_used(_bytes_used_during_gc);
4045 }
4046
4047 _preserved_marks_set.assert_empty();
4048
4049 merge_per_thread_state_info(per_thread_states);
4050
4051 // Reset and re-enable the hot card cache.
4052 // Note the counts for the cards in the regions in the
4053 // collection set are reset when the collection set is freed.
4054 _hot_card_cache->reset_hot_cache();
4055 _hot_card_cache->set_use_cache(true);
4056
4057 purge_code_root_memory();
4058
4059 redirty_logged_cards(rdcqs);
4060
4061 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4062
4063 eagerly_reclaim_humongous_regions();
4064
4065 record_obj_copy_mem_stats();
4066
4067 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4068 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4069
4070 #if COMPILER2_OR_JVMCI
4071 double start = os::elapsedTime();
4072 DerivedPointerTable::update_pointers();
4073 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4074 #endif
4075 policy()->print_age_table();
4076 }
4077
4078 void G1CollectedHeap::record_obj_copy_mem_stats() {
4079 policy()->old_gen_alloc_tracker()->
4080 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4081
4082 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4083 create_g1_evac_summary(&_old_evac_stats));
4084 }
4085
4086 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4087 assert(!hr->is_free(), "the region should not be free");
4088 assert(!hr->is_empty(), "the region should not be empty");
4089 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4090
4091 if (G1VerifyBitmaps) {
4092 MemRegion mr(hr->bottom(), hr->end());
4093 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4094 }
4095
4096 // Clear the card counts for this region.
4097 // Note: we only need to do this if the region is not young
4098 // (since we don't refine cards in young regions).
4099 if (!hr->is_young()) {
4100 _hot_card_cache->reset_card_counts(hr);
4101 }
4102
4103 // Reset region metadata to allow reuse.
4104 hr->hr_clear(true /* clear_space */);
4105 _policy->remset_tracker()->update_at_free(hr);
4106
4107 if (free_list != NULL) {
4108 free_list->add_ordered(hr);
4109 }
4110 }
4111
4112 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4113 FreeRegionList* free_list) {
4114 assert(hr->is_humongous(), "this is only for humongous regions");
4115 assert(free_list != NULL, "pre-condition");
4116 hr->clear_humongous();
4117 free_region(hr, free_list);
4118 }
4119
4120 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4121 const uint humongous_regions_removed) {
4122 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4123 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4124 _old_set.bulk_remove(old_regions_removed);
4125 _humongous_set.bulk_remove(humongous_regions_removed);
4126 }
4127
4128 }
4129
4130 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4131 assert(list != NULL, "list can't be null");
4132 if (!list->is_empty()) {
4133 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4134 _hrm->insert_list_into_free_list(list);
4135 }
4136 }
4137
4138 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4139 decrease_used(bytes);
4140 }
4141
4142 class G1FreeCollectionSetTask : public AbstractGangTask {
4143 // Helper class to keep statistics for the collection set freeing
4144 class FreeCSetStats {
4145 size_t _before_used_bytes; // Usage in regions successfully evacutate
4146 size_t _after_used_bytes; // Usage in regions failing evacuation
4147 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4148 size_t _failure_used_words; // Live size in failed regions
4149 size_t _failure_waste_words; // Wasted size in failed regions
4150 size_t _rs_length; // Remembered set size
4151 uint _regions_freed; // Number of regions freed
4152 public:
4153 FreeCSetStats() :
4154 _before_used_bytes(0),
4155 _after_used_bytes(0),
4156 _bytes_allocated_in_old_since_last_gc(0),
4157 _failure_used_words(0),
4158 _failure_waste_words(0),
4159 _rs_length(0),
4160 _regions_freed(0) { }
4161
4162 void merge_stats(FreeCSetStats* other) {
4163 assert(other != NULL, "invariant");
4164 _before_used_bytes += other->_before_used_bytes;
4165 _after_used_bytes += other->_after_used_bytes;
4166 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4167 _failure_used_words += other->_failure_used_words;
4168 _failure_waste_words += other->_failure_waste_words;
4169 _rs_length += other->_rs_length;
4170 _regions_freed += other->_regions_freed;
4171 }
4172
4173 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4174 evacuation_info->set_regions_freed(_regions_freed);
4175 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4176
4177 g1h->decrement_summary_bytes(_before_used_bytes);
4178 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4179
4180 G1Policy *policy = g1h->policy();
4181 policy->old_gen_alloc_tracker()->add_allocated_bytes_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4182 policy->record_rs_length(_rs_length);
4183 policy->cset_regions_freed();
4184 }
4185
4186 void account_failed_region(HeapRegion* r) {
4187 size_t used_words = r->marked_bytes() / HeapWordSize;
4188 _failure_used_words += used_words;
4189 _failure_waste_words += HeapRegion::GrainWords - used_words;
4190 _after_used_bytes += r->used();
4191
4192 // When moving a young gen region to old gen, we "allocate" that whole
4193 // region there. This is in addition to any already evacuated objects.
4194 // Notify the policy about that. Old gen regions do not cause an
4195 // additional allocation: both the objects still in the region and the
4196 // ones already moved are accounted for elsewhere.
4197 if (r->is_young()) {
4198 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4199 }
4200 }
4201
4202 void account_evacuated_region(HeapRegion* r) {
4203 _before_used_bytes += r->used();
4204 _regions_freed += 1;
4205 }
4206
4207 void account_rs_length(HeapRegion* r) {
4208 _rs_length += r->rem_set()->occupied();
4209 }
4210 };
4211
4212 // Closure applied to all regions in the collection set.
4213 class FreeCSetClosure : public HeapRegionClosure {
4214 // Helper to send JFR events for regions.
4215 class JFREventForRegion {
4216 EventGCPhaseParallel _event;
4217 public:
4218 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4219 _event.set_gcId(GCId::current());
4220 _event.set_gcWorkerId(worker_id);
4221 if (region->is_young()) {
4222 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4223 } else {
4224 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4225 }
4226 }
4227
4228 ~JFREventForRegion() {
4229 _event.commit();
4230 }
4231 };
4232
4233 // Helper to do timing for region work.
4234 class TimerForRegion {
4235 Tickspan& _time;
4236 Ticks _start_time;
4237 public:
4238 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4239 ~TimerForRegion() {
4240 _time += Ticks::now() - _start_time;
4241 }
4242 };
4243
4244 // FreeCSetClosure members
4245 G1CollectedHeap* _g1h;
4246 const size_t* _surviving_young_words;
4247 uint _worker_id;
4248 Tickspan _young_time;
4249 Tickspan _non_young_time;
4250 FreeCSetStats* _stats;
4251
4252 void assert_in_cset(HeapRegion* r) {
4253 assert(r->young_index_in_cset() != 0 &&
4254 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4255 "Young index %u is wrong for region %u of type %s with %u young regions",
4256 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4257 }
4258
4259 void handle_evacuated_region(HeapRegion* r) {
4260 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4261 stats()->account_evacuated_region(r);
4262
4263 // Free the region and and its remembered set.
4264 _g1h->free_region(r, NULL);
4265 }
4266
4267 void handle_failed_region(HeapRegion* r) {
4268 // Do some allocation statistics accounting. Regions that failed evacuation
4269 // are always made old, so there is no need to update anything in the young
4270 // gen statistics, but we need to update old gen statistics.
4271 stats()->account_failed_region(r);
4272
4273 // Update the region state due to the failed evacuation.
4274 r->handle_evacuation_failure();
4275
4276 // Add region to old set, need to hold lock.
4277 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4278 _g1h->old_set_add(r);
4279 }
4280
4281 Tickspan& timer_for_region(HeapRegion* r) {
4282 return r->is_young() ? _young_time : _non_young_time;
4283 }
4284
4285 FreeCSetStats* stats() {
4286 return _stats;
4287 }
4288 public:
4289 FreeCSetClosure(const size_t* surviving_young_words,
4290 uint worker_id,
4291 FreeCSetStats* stats) :
4292 HeapRegionClosure(),
4293 _g1h(G1CollectedHeap::heap()),
4294 _surviving_young_words(surviving_young_words),
4295 _worker_id(worker_id),
4296 _young_time(),
4297 _non_young_time(),
4298 _stats(stats) { }
4299
4300 virtual bool do_heap_region(HeapRegion* r) {
4301 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4302 JFREventForRegion event(r, _worker_id);
4303 TimerForRegion timer(timer_for_region(r));
4304
4305 _g1h->clear_region_attr(r);
4306 stats()->account_rs_length(r);
4307
4308 if (r->is_young()) {
4309 assert_in_cset(r);
4310 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4311 }
4312
4313 if (r->evacuation_failed()) {
4314 handle_failed_region(r);
4315 } else {
4316 handle_evacuated_region(r);
4317 }
4318 assert(!_g1h->is_on_master_free_list(r), "sanity");
4319
4320 return false;
4321 }
4322
4323 void report_timing(Tickspan parallel_time) {
4324 G1GCPhaseTimes* pt = _g1h->phase_times();
4325 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4326 if (_young_time.value() > 0) {
4327 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4328 }
4329 if (_non_young_time.value() > 0) {
4330 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4331 }
4332 }
4333 };
4334
4335 // G1FreeCollectionSetTask members
4336 G1CollectedHeap* _g1h;
4337 G1EvacuationInfo* _evacuation_info;
4338 FreeCSetStats* _worker_stats;
4339 HeapRegionClaimer _claimer;
4340 const size_t* _surviving_young_words;
4341 uint _active_workers;
4342
4343 FreeCSetStats* worker_stats(uint worker) {
4344 return &_worker_stats[worker];
4345 }
4346
4347 void report_statistics() {
4348 // Merge the accounting
4349 FreeCSetStats total_stats;
4350 for (uint worker = 0; worker < _active_workers; worker++) {
4351 total_stats.merge_stats(worker_stats(worker));
4352 }
4353 total_stats.report(_g1h, _evacuation_info);
4354 }
4355
4356 public:
4357 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4358 AbstractGangTask("G1 Free Collection Set"),
4359 _g1h(G1CollectedHeap::heap()),
4360 _evacuation_info(evacuation_info),
4361 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4362 _claimer(active_workers),
4363 _surviving_young_words(surviving_young_words),
4364 _active_workers(active_workers) {
4365 for (uint worker = 0; worker < active_workers; worker++) {
4366 ::new (&_worker_stats[worker]) FreeCSetStats();
4367 }
4368 }
4369
4370 ~G1FreeCollectionSetTask() {
4371 Ticks serial_time = Ticks::now();
4372 report_statistics();
4373 for (uint worker = 0; worker < _active_workers; worker++) {
4374 _worker_stats[worker].~FreeCSetStats();
4375 }
4376 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4377 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4378 }
4379
4380 virtual void work(uint worker_id) {
4381 EventGCPhaseParallel event;
4382 Ticks start = Ticks::now();
4383 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4384 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4385
4386 // Report the total parallel time along with some more detailed metrics.
4387 cl.report_timing(Ticks::now() - start);
4388 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4389 }
4390 };
4391
4392 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4393 _eden.clear();
4394
4395 // The free collections set is split up in two tasks, the first
4396 // frees the collection set and records what regions are free,
4397 // and the second one rebuilds the free list. This proved to be
4398 // more efficient than adding a sorted list to another.
4399
4400 Ticks free_cset_start_time = Ticks::now();
4401 {
4402 uint const num_cs_regions = _collection_set.region_length();
4403 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4404 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4405
4406 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4407 cl.name(), num_workers, num_cs_regions, num_regions());
4408 workers()->run_task(&cl, num_workers);
4409 }
4410
4411 Ticks free_cset_end_time = Ticks::now();
4412 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4413
4414 // Now rebuild the free region list.
4415 hrm()->rebuild_free_list(workers());
4416 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4417
4418 collection_set->clear();
4419 }
4420
4421 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4422 private:
4423 FreeRegionList* _free_region_list;
4424 HeapRegionSet* _proxy_set;
4425 uint _humongous_objects_reclaimed;
4426 uint _humongous_regions_reclaimed;
4427 size_t _freed_bytes;
4428 public:
4429
4430 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4431 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4432 }
4433
4434 virtual bool do_heap_region(HeapRegion* r) {
4435 if (!r->is_starts_humongous()) {
4436 return false;
4437 }
4438
4439 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4440
4441 oop obj = (oop)r->bottom();
4442 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4443
4444 // The following checks whether the humongous object is live are sufficient.
4445 // The main additional check (in addition to having a reference from the roots
4446 // or the young gen) is whether the humongous object has a remembered set entry.
4447 //
4448 // A humongous object cannot be live if there is no remembered set for it
4449 // because:
4450 // - there can be no references from within humongous starts regions referencing
4451 // the object because we never allocate other objects into them.
4452 // (I.e. there are no intra-region references that may be missed by the
4453 // remembered set)
4454 // - as soon there is a remembered set entry to the humongous starts region
4455 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4456 // until the end of a concurrent mark.
4457 //
4458 // It is not required to check whether the object has been found dead by marking
4459 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4460 // all objects allocated during that time are considered live.
4461 // SATB marking is even more conservative than the remembered set.
4462 // So if at this point in the collection there is no remembered set entry,
4463 // nobody has a reference to it.
4464 // At the start of collection we flush all refinement logs, and remembered sets
4465 // are completely up-to-date wrt to references to the humongous object.
4466 //
4467 // Other implementation considerations:
4468 // - never consider object arrays at this time because they would pose
4469 // considerable effort for cleaning up the the remembered sets. This is
4470 // required because stale remembered sets might reference locations that
4471 // are currently allocated into.
4472 uint region_idx = r->hrm_index();
4473 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4474 !r->rem_set()->is_empty()) {
4475 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",
4476 region_idx,
4477 (size_t)obj->size() * HeapWordSize,
4478 p2i(r->bottom()),
4479 r->rem_set()->occupied(),
4480 r->rem_set()->strong_code_roots_list_length(),
4481 next_bitmap->is_marked(r->bottom()),
4482 g1h->is_humongous_reclaim_candidate(region_idx),
4483 obj->is_typeArray()
4484 );
4485 return false;
4486 }
4487
4488 guarantee(obj->is_typeArray(),
4489 "Only eagerly reclaiming type arrays is supported, but the object "
4490 PTR_FORMAT " is not.", p2i(r->bottom()));
4491
4492 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",
4493 region_idx,
4494 (size_t)obj->size() * HeapWordSize,
4495 p2i(r->bottom()),
4496 r->rem_set()->occupied(),
4497 r->rem_set()->strong_code_roots_list_length(),
4498 next_bitmap->is_marked(r->bottom()),
4499 g1h->is_humongous_reclaim_candidate(region_idx),
4500 obj->is_typeArray()
4501 );
4502
4503 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4504 cm->humongous_object_eagerly_reclaimed(r);
4505 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4506 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4507 region_idx,
4508 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4509 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4510 _humongous_objects_reclaimed++;
4511 do {
4512 HeapRegion* next = g1h->next_region_in_humongous(r);
4513 _freed_bytes += r->used();
4514 r->set_containing_set(NULL);
4515 _humongous_regions_reclaimed++;
4516 g1h->free_humongous_region(r, _free_region_list);
4517 r = next;
4518 } while (r != NULL);
4519
4520 return false;
4521 }
4522
4523 uint humongous_objects_reclaimed() {
4524 return _humongous_objects_reclaimed;
4525 }
4526
4527 uint humongous_regions_reclaimed() {
4528 return _humongous_regions_reclaimed;
4529 }
4530
4531 size_t bytes_freed() const {
4532 return _freed_bytes;
4533 }
4534 };
4535
4536 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4537 assert_at_safepoint_on_vm_thread();
4538
4539 if (!G1EagerReclaimHumongousObjects ||
4540 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4541 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4542 return;
4543 }
4544
4545 double start_time = os::elapsedTime();
4546
4547 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4548
4549 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4550 heap_region_iterate(&cl);
4551
4552 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4553
4554 G1HRPrinter* hrp = hr_printer();
4555 if (hrp->is_active()) {
4556 FreeRegionListIterator iter(&local_cleanup_list);
4557 while (iter.more_available()) {
4558 HeapRegion* hr = iter.get_next();
4559 hrp->cleanup(hr);
4560 }
4561 }
4562
4563 prepend_to_freelist(&local_cleanup_list);
4564 decrement_summary_bytes(cl.bytes_freed());
4565
4566 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4567 cl.humongous_objects_reclaimed());
4568 }
4569
4570 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4571 public:
4572 virtual bool do_heap_region(HeapRegion* r) {
4573 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4574 G1CollectedHeap::heap()->clear_region_attr(r);
4575 r->clear_young_index_in_cset();
4576 return false;
4577 }
4578 };
4579
4580 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4581 G1AbandonCollectionSetClosure cl;
4582 collection_set_iterate_all(&cl);
4583
4584 collection_set->clear();
4585 collection_set->stop_incremental_building();
4586 }
4587
4588 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4589 return _allocator->is_retained_old_region(hr);
4590 }
4591
4592 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4593 _eden.add(hr);
4594 _policy->set_region_eden(hr);
4595 }
4596
4597 #ifdef ASSERT
4598
4599 class NoYoungRegionsClosure: public HeapRegionClosure {
4600 private:
4601 bool _success;
4602 public:
4603 NoYoungRegionsClosure() : _success(true) { }
4604 bool do_heap_region(HeapRegion* r) {
4605 if (r->is_young()) {
4606 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4607 p2i(r->bottom()), p2i(r->end()));
4608 _success = false;
4609 }
4610 return false;
4611 }
4612 bool success() { return _success; }
4613 };
4614
4615 bool G1CollectedHeap::check_young_list_empty() {
4616 bool ret = (young_regions_count() == 0);
4617
4618 NoYoungRegionsClosure closure;
4619 heap_region_iterate(&closure);
4620 ret = ret && closure.success();
4621
4622 return ret;
4623 }
4624
4625 #endif // ASSERT
4626
4627 class TearDownRegionSetsClosure : public HeapRegionClosure {
4628 HeapRegionSet *_old_set;
4629
4630 public:
4631 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4632
4633 bool do_heap_region(HeapRegion* r) {
4634 if (r->is_old()) {
4635 _old_set->remove(r);
4636 } else if(r->is_young()) {
4637 r->uninstall_surv_rate_group();
4638 } else {
4639 // We ignore free regions, we'll empty the free list afterwards.
4640 // We ignore humongous and archive regions, we're not tearing down these
4641 // sets.
4642 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4643 "it cannot be another type");
4644 }
4645 return false;
4646 }
4647
4648 ~TearDownRegionSetsClosure() {
4649 assert(_old_set->is_empty(), "post-condition");
4650 }
4651 };
4652
4653 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4654 assert_at_safepoint_on_vm_thread();
4655
4656 if (!free_list_only) {
4657 TearDownRegionSetsClosure cl(&_old_set);
4658 heap_region_iterate(&cl);
4659
4660 // Note that emptying the _young_list is postponed and instead done as
4661 // the first step when rebuilding the regions sets again. The reason for
4662 // this is that during a full GC string deduplication needs to know if
4663 // a collected region was young or old when the full GC was initiated.
4664 }
4665 _hrm->remove_all_free_regions();
4666 }
4667
4668 void G1CollectedHeap::increase_used(size_t bytes) {
4669 _summary_bytes_used += bytes;
4670 }
4671
4672 void G1CollectedHeap::decrease_used(size_t bytes) {
4673 assert(_summary_bytes_used >= bytes,
4674 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4675 _summary_bytes_used, bytes);
4676 _summary_bytes_used -= bytes;
4677 }
4678
4679 void G1CollectedHeap::set_used(size_t bytes) {
4680 _summary_bytes_used = bytes;
4681 }
4682
4683 class RebuildRegionSetsClosure : public HeapRegionClosure {
4684 private:
4685 bool _free_list_only;
4686
4687 HeapRegionSet* _old_set;
4688 HeapRegionManager* _hrm;
4689
4690 size_t _total_used;
4691
4692 public:
4693 RebuildRegionSetsClosure(bool free_list_only,
4694 HeapRegionSet* old_set,
4695 HeapRegionManager* hrm) :
4696 _free_list_only(free_list_only),
4697 _old_set(old_set), _hrm(hrm), _total_used(0) {
4698 assert(_hrm->num_free_regions() == 0, "pre-condition");
4699 if (!free_list_only) {
4700 assert(_old_set->is_empty(), "pre-condition");
4701 }
4702 }
4703
4704 bool do_heap_region(HeapRegion* r) {
4705 if (r->is_empty()) {
4706 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4707 // Add free regions to the free list
4708 r->set_free();
4709 _hrm->insert_into_free_list(r);
4710 } else if (!_free_list_only) {
4711 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4712
4713 if (r->is_archive() || r->is_humongous()) {
4714 // We ignore archive and humongous regions. We left these sets unchanged.
4715 } else {
4716 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4717 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4718 r->move_to_old();
4719 _old_set->add(r);
4720 }
4721 _total_used += r->used();
4722 }
4723
4724 return false;
4725 }
4726
4727 size_t total_used() {
4728 return _total_used;
4729 }
4730 };
4731
4732 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4733 assert_at_safepoint_on_vm_thread();
4734
4735 if (!free_list_only) {
4736 _eden.clear();
4737 _survivor.clear();
4738 }
4739
4740 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4741 heap_region_iterate(&cl);
4742
4743 if (!free_list_only) {
4744 set_used(cl.total_used());
4745 if (_archive_allocator != NULL) {
4746 _archive_allocator->clear_used();
4747 }
4748 }
4749 assert_used_and_recalculate_used_equal(this);
4750 }
4751
4752 // Methods for the mutator alloc region
4753
4754 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4755 bool force,
4756 uint node_index) {
4757 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4758 bool should_allocate = policy()->should_allocate_mutator_region();
4759 if (force || should_allocate) {
4760 HeapRegion* new_alloc_region = new_region(word_size,
4761 HeapRegionType::Eden,
4762 false /* do_expand */,
4763 node_index);
4764 if (new_alloc_region != NULL) {
4765 set_region_short_lived_locked(new_alloc_region);
4766 _hr_printer.alloc(new_alloc_region, !should_allocate);
4767 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4768 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4769 return new_alloc_region;
4770 }
4771 }
4772 return NULL;
4773 }
4774
4775 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4776 size_t allocated_bytes) {
4777 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4778 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4779
4780 collection_set()->add_eden_region(alloc_region);
4781 increase_used(allocated_bytes);
4782 _eden.add_used_bytes(allocated_bytes);
4783 _hr_printer.retire(alloc_region);
4784
4785 // We update the eden sizes here, when the region is retired,
4786 // instead of when it's allocated, since this is the point that its
4787 // used space has been recorded in _summary_bytes_used.
4788 g1mm()->update_eden_size();
4789 }
4790
4791 // Methods for the GC alloc regions
4792
4793 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4794 if (dest.is_old()) {
4795 return true;
4796 } else {
4797 return survivor_regions_count() < policy()->max_survivor_regions();
4798 }
4799 }
4800
4801 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4802 assert(FreeList_lock->owned_by_self(), "pre-condition");
4803
4804 if (!has_more_regions(dest)) {
4805 return NULL;
4806 }
4807
4808 HeapRegionType type;
4809 if (dest.is_young()) {
4810 type = HeapRegionType::Survivor;
4811 } else {
4812 type = HeapRegionType::Old;
4813 }
4814
4815 HeapRegion* new_alloc_region = new_region(word_size,
4816 type,
4817 true /* do_expand */,
4818 node_index);
4819
4820 if (new_alloc_region != NULL) {
4821 if (type.is_survivor()) {
4822 new_alloc_region->set_survivor();
4823 _survivor.add(new_alloc_region);
4824 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4825 } else {
4826 new_alloc_region->set_old();
4827 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4828 }
4829 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4830 register_region_with_region_attr(new_alloc_region);
4831 _hr_printer.alloc(new_alloc_region);
4832 return new_alloc_region;
4833 }
4834 return NULL;
4835 }
4836
4837 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4838 size_t allocated_bytes,
4839 G1HeapRegionAttr dest) {
4840 _bytes_used_during_gc += allocated_bytes;
4841 if (dest.is_old()) {
4842 old_set_add(alloc_region);
4843 } else {
4844 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4845 _survivor.add_used_bytes(allocated_bytes);
4846 }
4847
4848 bool const during_im = collector_state()->in_initial_mark_gc();
4849 if (during_im && allocated_bytes > 0) {
4850 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4851 }
4852 _hr_printer.retire(alloc_region);
4853 }
4854
4855 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4856 bool expanded = false;
4857 uint index = _hrm->find_highest_free(&expanded);
4858
4859 if (index != G1_NO_HRM_INDEX) {
4860 if (expanded) {
4861 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4862 HeapRegion::GrainWords * HeapWordSize);
4863 }
4864 return _hrm->allocate_free_regions_starting_at(index, 1);
4865 }
4866 return NULL;
4867 }
4868
4869 // Optimized nmethod scanning
4870
4871 class RegisterNMethodOopClosure: public OopClosure {
4872 G1CollectedHeap* _g1h;
4873 nmethod* _nm;
4874
4875 template <class T> void do_oop_work(T* p) {
4876 T heap_oop = RawAccess<>::oop_load(p);
4877 if (!CompressedOops::is_null(heap_oop)) {
4878 oop obj = CompressedOops::decode_not_null(heap_oop);
4879 HeapRegion* hr = _g1h->heap_region_containing(obj);
4880 assert(!hr->is_continues_humongous(),
4881 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4882 " starting at " HR_FORMAT,
4883 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4884
4885 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4886 hr->add_strong_code_root_locked(_nm);
4887 }
4888 }
4889
4890 public:
4891 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4892 _g1h(g1h), _nm(nm) {}
4893
4894 void do_oop(oop* p) { do_oop_work(p); }
4895 void do_oop(narrowOop* p) { do_oop_work(p); }
4896 };
4897
4898 class UnregisterNMethodOopClosure: public OopClosure {
4899 G1CollectedHeap* _g1h;
4900 nmethod* _nm;
4901
4902 template <class T> void do_oop_work(T* p) {
4903 T heap_oop = RawAccess<>::oop_load(p);
4904 if (!CompressedOops::is_null(heap_oop)) {
4905 oop obj = CompressedOops::decode_not_null(heap_oop);
4906 HeapRegion* hr = _g1h->heap_region_containing(obj);
4907 assert(!hr->is_continues_humongous(),
4908 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4909 " starting at " HR_FORMAT,
4910 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4911
4912 hr->remove_strong_code_root(_nm);
4913 }
4914 }
4915
4916 public:
4917 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4918 _g1h(g1h), _nm(nm) {}
4919
4920 void do_oop(oop* p) { do_oop_work(p); }
4921 void do_oop(narrowOop* p) { do_oop_work(p); }
4922 };
4923
4924 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4925 guarantee(nm != NULL, "sanity");
4926 RegisterNMethodOopClosure reg_cl(this, nm);
4927 nm->oops_do(®_cl);
4928 }
4929
4930 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4931 guarantee(nm != NULL, "sanity");
4932 UnregisterNMethodOopClosure reg_cl(this, nm);
4933 nm->oops_do(®_cl, true);
4934 }
4935
4936 void G1CollectedHeap::purge_code_root_memory() {
4937 double purge_start = os::elapsedTime();
4938 G1CodeRootSet::purge();
4939 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4940 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4941 }
4942
4943 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4944 G1CollectedHeap* _g1h;
4945
4946 public:
4947 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4948 _g1h(g1h) {}
4949
4950 void do_code_blob(CodeBlob* cb) {
4951 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4952 if (nm == NULL) {
4953 return;
4954 }
4955
4956 _g1h->register_nmethod(nm);
4957 }
4958 };
4959
4960 void G1CollectedHeap::rebuild_strong_code_roots() {
4961 RebuildStrongCodeRootClosure blob_cl(this);
4962 CodeCache::blobs_do(&blob_cl);
4963 }
4964
4965 void G1CollectedHeap::initialize_serviceability() {
4966 _g1mm->initialize_serviceability();
4967 }
4968
4969 MemoryUsage G1CollectedHeap::memory_usage() {
4970 return _g1mm->memory_usage();
4971 }
4972
4973 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4974 return _g1mm->memory_managers();
4975 }
4976
4977 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4978 return _g1mm->memory_pools();
4979 }
--- EOF ---