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