1 /*
2 * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/g1/g1Allocator.inline.hpp"
32 #include "gc/g1/g1Arguments.hpp"
33 #include "gc/g1/g1BarrierSet.hpp"
34 #include "gc/g1/g1CardTableEntryClosure.hpp"
35 #include "gc/g1/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCPhaseTimes.hpp"
45 #include "gc/g1/g1HeapSizingPolicy.hpp"
46 #include "gc/g1/g1HeapTransition.hpp"
47 #include "gc/g1/g1HeapVerifier.hpp"
48 #include "gc/g1/g1HotCardCache.hpp"
49 #include "gc/g1/g1MemoryPool.hpp"
50 #include "gc/g1/g1OopClosures.inline.hpp"
51 #include "gc/g1/g1ParallelCleaning.hpp"
52 #include "gc/g1/g1ParScanThreadState.inline.hpp"
53 #include "gc/g1/g1Policy.hpp"
54 #include "gc/g1/g1RedirtyCardsQueue.hpp"
55 #include "gc/g1/g1RegionToSpaceMapper.hpp"
56 #include "gc/g1/g1RemSet.hpp"
57 #include "gc/g1/g1RootClosures.hpp"
58 #include "gc/g1/g1RootProcessor.hpp"
59 #include "gc/g1/g1SATBMarkQueueSet.hpp"
60 #include "gc/g1/g1StringDedup.hpp"
61 #include "gc/g1/g1ThreadLocalData.hpp"
62 #include "gc/g1/g1Trace.hpp"
63 #include "gc/g1/g1YCTypes.hpp"
64 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
65 #include "gc/g1/g1VMOperations.hpp"
66 #include "gc/g1/heapRegion.inline.hpp"
67 #include "gc/g1/heapRegionRemSet.hpp"
68 #include "gc/g1/heapRegionSet.inline.hpp"
69 #include "gc/shared/concurrentGCBreakpoints.hpp"
70 #include "gc/shared/gcBehaviours.hpp"
71 #include "gc/shared/gcHeapSummary.hpp"
72 #include "gc/shared/gcId.hpp"
73 #include "gc/shared/gcLocker.hpp"
74 #include "gc/shared/gcTimer.hpp"
75 #include "gc/shared/gcTraceTime.inline.hpp"
76 #include "gc/shared/generationSpec.hpp"
77 #include "gc/shared/isGCActiveMark.hpp"
78 #include "gc/shared/locationPrinter.inline.hpp"
79 #include "gc/shared/oopStorageParState.hpp"
80 #include "gc/shared/preservedMarks.inline.hpp"
81 #include "gc/shared/suspendibleThreadSet.hpp"
82 #include "gc/shared/referenceProcessor.inline.hpp"
83 #include "gc/shared/taskTerminator.hpp"
84 #include "gc/shared/taskqueue.inline.hpp"
85 #include "gc/shared/weakProcessor.inline.hpp"
86 #include "gc/shared/workerPolicy.hpp"
87 #include "logging/log.hpp"
88 #include "memory/allocation.hpp"
89 #include "memory/iterator.hpp"
90 #include "memory/resourceArea.hpp"
91 #include "memory/universe.hpp"
92 #include "oops/access.inline.hpp"
93 #include "oops/compressedOops.inline.hpp"
94 #include "oops/oop.inline.hpp"
95 #include "runtime/atomic.hpp"
96 #include "runtime/flags/flagSetting.hpp"
97 #include "runtime/handles.inline.hpp"
98 #include "runtime/init.hpp"
99 #include "runtime/orderAccess.hpp"
100 #include "runtime/threadSMR.hpp"
101 #include "runtime/vmThread.hpp"
102 #include "utilities/align.hpp"
103 #include "utilities/bitMap.inline.hpp"
104 #include "utilities/globalDefinitions.hpp"
105 #include "utilities/stack.inline.hpp"
106
107 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
108
109 // INVARIANTS/NOTES
110 //
111 // All allocation activity covered by the G1CollectedHeap interface is
112 // serialized by acquiring the HeapLock. This happens in mem_allocate
113 // and allocate_new_tlab, which are the "entry" points to the
114 // allocation code from the rest of the JVM. (Note that this does not
115 // apply to TLAB allocation, which is not part of this interface: it
116 // is done by clients of this interface.)
117
118 class RedirtyLoggedCardTableEntryClosure : public G1CardTableEntryClosure {
119 private:
120 size_t _num_dirtied;
121 G1CollectedHeap* _g1h;
122 G1CardTable* _g1_ct;
123
124 HeapRegion* region_for_card(CardValue* card_ptr) const {
125 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
126 }
127
128 bool will_become_free(HeapRegion* hr) const {
129 // A region will be freed by free_collection_set if the region is in the
130 // collection set and has not had an evacuation failure.
131 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
132 }
133
134 public:
135 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : G1CardTableEntryClosure(),
136 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
137
138 void do_card_ptr(CardValue* card_ptr, uint worker_id) {
139 HeapRegion* hr = region_for_card(card_ptr);
140
141 // Should only dirty cards in regions that won't be freed.
142 if (!will_become_free(hr)) {
143 *card_ptr = G1CardTable::dirty_card_val();
144 _num_dirtied++;
145 }
146 }
147
148 size_t num_dirtied() const { return _num_dirtied; }
149 };
150
151
152 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
153 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
154 }
155
156 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
157 // The from card cache is not the memory that is actually committed. So we cannot
158 // take advantage of the zero_filled parameter.
159 reset_from_card_cache(start_idx, num_regions);
160 }
161
162 Tickspan G1CollectedHeap::run_task(AbstractGangTask* task) {
163 Ticks start = Ticks::now();
164 workers()->run_task(task, workers()->active_workers());
165 return Ticks::now() - start;
166 }
167
168 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
169 MemRegion mr) {
170 return new HeapRegion(hrs_index, bot(), mr);
171 }
172
173 // Private methods.
174
175 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
176 HeapRegionType type,
177 bool do_expand,
178 uint node_index) {
179 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
180 "the only time we use this to allocate a humongous region is "
181 "when we are allocating a single humongous region");
182
183 HeapRegion* res = _hrm->allocate_free_region(type, node_index);
184
185 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
186 // Currently, only attempts to allocate GC alloc regions set
187 // do_expand to true. So, we should only reach here during a
188 // safepoint. If this assumption changes we might have to
189 // reconsider the use of _expand_heap_after_alloc_failure.
190 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
191
192 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
193 word_size * HeapWordSize);
194
195 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
196 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
197 word_size * HeapWordSize);
198 if (expand_single_region(node_index)) {
199 // Given that expand_single_region() succeeded in expanding the heap, and we
200 // always expand the heap by an amount aligned to the heap
201 // region size, the free list should in theory not be empty.
202 // In either case allocate_free_region() will check for NULL.
203 res = _hrm->allocate_free_region(type, node_index);
204 } else {
205 _expand_heap_after_alloc_failure = false;
206 }
207 }
208 return res;
209 }
210
211 HeapWord*
212 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
213 uint num_regions,
214 size_t word_size) {
215 assert(first_hr != NULL, "pre-condition");
216 assert(is_humongous(word_size), "word_size should be humongous");
217 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
218
219 // Index of last region in the series.
220 uint first = first_hr->hrm_index();
221 uint last = first + num_regions - 1;
222
223 // We need to initialize the region(s) we just discovered. This is
224 // a bit tricky given that it can happen concurrently with
225 // refinement threads refining cards on these regions and
226 // potentially wanting to refine the BOT as they are scanning
227 // those cards (this can happen shortly after a cleanup; see CR
228 // 6991377). So we have to set up the region(s) carefully and in
229 // a specific order.
230
231 // The word size sum of all the regions we will allocate.
232 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
233 assert(word_size <= word_size_sum, "sanity");
234
235 // The passed in hr will be the "starts humongous" region. The header
236 // of the new object will be placed at the bottom of this region.
237 HeapWord* new_obj = first_hr->bottom();
238 // This will be the new top of the new object.
239 HeapWord* obj_top = new_obj + word_size;
240
241 // First, we need to zero the header of the space that we will be
242 // allocating. When we update top further down, some refinement
243 // threads might try to scan the region. By zeroing the header we
244 // ensure that any thread that will try to scan the region will
245 // come across the zero klass word and bail out.
246 //
247 // NOTE: It would not have been correct to have used
248 // CollectedHeap::fill_with_object() and make the space look like
249 // an int array. The thread that is doing the allocation will
250 // later update the object header to a potentially different array
251 // type and, for a very short period of time, the klass and length
252 // fields will be inconsistent. This could cause a refinement
253 // thread to calculate the object size incorrectly.
254 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
255
256 // Next, pad out the unused tail of the last region with filler
257 // objects, for improved usage accounting.
258 // How many words we use for filler objects.
259 size_t word_fill_size = word_size_sum - word_size;
260
261 // How many words memory we "waste" which cannot hold a filler object.
262 size_t words_not_fillable = 0;
263
264 if (word_fill_size >= min_fill_size()) {
265 fill_with_objects(obj_top, word_fill_size);
266 } else if (word_fill_size > 0) {
267 // We have space to fill, but we cannot fit an object there.
268 words_not_fillable = word_fill_size;
269 word_fill_size = 0;
270 }
271
272 // We will set up the first region as "starts humongous". This
273 // will also update the BOT covering all the regions to reflect
274 // that there is a single object that starts at the bottom of the
275 // first region.
276 first_hr->set_starts_humongous(obj_top, word_fill_size);
277 _policy->remset_tracker()->update_at_allocate(first_hr);
278 // Then, if there are any, we will set up the "continues
279 // humongous" regions.
280 HeapRegion* hr = NULL;
281 for (uint i = first + 1; i <= last; ++i) {
282 hr = region_at(i);
283 hr->set_continues_humongous(first_hr);
284 _policy->remset_tracker()->update_at_allocate(hr);
285 }
286
287 // Up to this point no concurrent thread would have been able to
288 // do any scanning on any region in this series. All the top
289 // fields still point to bottom, so the intersection between
290 // [bottom,top] and [card_start,card_end] will be empty. Before we
291 // update the top fields, we'll do a storestore to make sure that
292 // no thread sees the update to top before the zeroing of the
293 // object header and the BOT initialization.
294 OrderAccess::storestore();
295
296 // Now, we will update the top fields of the "continues humongous"
297 // regions except the last one.
298 for (uint i = first; i < last; ++i) {
299 hr = region_at(i);
300 hr->set_top(hr->end());
301 }
302
303 hr = region_at(last);
304 // If we cannot fit a filler object, we must set top to the end
305 // of the humongous object, otherwise we cannot iterate the heap
306 // and the BOT will not be complete.
307 hr->set_top(hr->end() - words_not_fillable);
308
309 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
310 "obj_top should be in last region");
311
312 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
313
314 assert(words_not_fillable == 0 ||
315 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
316 "Miscalculation in humongous allocation");
317
318 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
319
320 for (uint i = first; i <= last; ++i) {
321 hr = region_at(i);
322 _humongous_set.add(hr);
323 _hr_printer.alloc(hr);
324 }
325
326 return new_obj;
327 }
328
329 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
330 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
331 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
332 }
333
334 // If could fit into free regions w/o expansion, try.
335 // Otherwise, if can expand, do so.
336 // Otherwise, if using ex regions might help, try with ex given back.
337 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
338 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
339
340 _verifier->verify_region_sets_optional();
341
342 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
343
344 // Policy: First try to allocate a humongous object in the free list.
345 HeapRegion* humongous_start = _hrm->allocate_humongous(obj_regions);
346 if (humongous_start == NULL) {
347 // Policy: We could not find enough regions for the humongous object in the
348 // free list. Look through the heap to find a mix of free and uncommitted regions.
349 // If so, expand the heap and allocate the humongous object.
350 humongous_start = _hrm->expand_and_allocate_humongous(obj_regions);
351 if (humongous_start != NULL) {
352 // We managed to find a region by expanding the heap.
353 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
354 word_size * HeapWordSize);
355 policy()->record_new_heap_size(num_regions());
356 } else {
357 // Policy: Potentially trigger a defragmentation GC.
358 }
359 }
360
361 HeapWord* result = NULL;
362 if (humongous_start != NULL) {
363 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
364 assert(result != NULL, "it should always return a valid result");
365
366 // A successful humongous object allocation changes the used space
367 // information of the old generation so we need to recalculate the
368 // sizes and update the jstat counters here.
369 g1mm()->update_sizes();
370 }
371
372 _verifier->verify_region_sets_optional();
373
374 return result;
375 }
376
377 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
378 size_t requested_size,
379 size_t* actual_size) {
380 assert_heap_not_locked_and_not_at_safepoint();
381 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
382
383 return attempt_allocation(min_size, requested_size, actual_size);
384 }
385
386 HeapWord*
387 G1CollectedHeap::mem_allocate(size_t word_size,
388 bool* gc_overhead_limit_was_exceeded) {
389 assert_heap_not_locked_and_not_at_safepoint();
390
391 if (is_humongous(word_size)) {
392 return attempt_allocation_humongous(word_size);
393 }
394 size_t dummy = 0;
395 return attempt_allocation(word_size, word_size, &dummy);
396 }
397
398 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
399 ResourceMark rm; // For retrieving the thread names in log messages.
400
401 // Make sure you read the note in attempt_allocation_humongous().
402
403 assert_heap_not_locked_and_not_at_safepoint();
404 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
405 "be called for humongous allocation requests");
406
407 // We should only get here after the first-level allocation attempt
408 // (attempt_allocation()) failed to allocate.
409
410 // We will loop until a) we manage to successfully perform the
411 // allocation or b) we successfully schedule a collection which
412 // fails to perform the allocation. b) is the only case when we'll
413 // return NULL.
414 HeapWord* result = NULL;
415 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
416 bool should_try_gc;
417 uint gc_count_before;
418
419 {
420 MutexLocker x(Heap_lock);
421 result = _allocator->attempt_allocation_locked(word_size);
422 if (result != NULL) {
423 return result;
424 }
425
426 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
427 // This is different to when only GCLocker::needs_gc() is set: try to avoid
428 // waiting because the GCLocker is active to not wait too long.
429 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
430 // No need for an ergo message here, can_expand_young_list() does this when
431 // it returns true.
432 result = _allocator->attempt_allocation_force(word_size);
433 if (result != NULL) {
434 return result;
435 }
436 }
437 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
438 // the GCLocker initiated GC has been performed and then retry. This includes
439 // the case when the GC Locker is not active but has not been performed.
440 should_try_gc = !GCLocker::needs_gc();
441 // Read the GC count while still holding the Heap_lock.
442 gc_count_before = total_collections();
443 }
444
445 if (should_try_gc) {
446 bool succeeded;
447 result = do_collection_pause(word_size, gc_count_before, &succeeded,
448 GCCause::_g1_inc_collection_pause);
449 if (result != NULL) {
450 assert(succeeded, "only way to get back a non-NULL result");
451 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
452 Thread::current()->name(), p2i(result));
453 return result;
454 }
455
456 if (succeeded) {
457 // We successfully scheduled a collection which failed to allocate. No
458 // point in trying to allocate further. We'll just return NULL.
459 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
460 SIZE_FORMAT " words", Thread::current()->name(), word_size);
461 return NULL;
462 }
463 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
464 Thread::current()->name(), word_size);
465 } else {
466 // Failed to schedule a collection.
467 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
468 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
469 SIZE_FORMAT " words", Thread::current()->name(), word_size);
470 return NULL;
471 }
472 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
473 // The GCLocker is either active or the GCLocker initiated
474 // GC has not yet been performed. Stall until it is and
475 // then retry the allocation.
476 GCLocker::stall_until_clear();
477 gclocker_retry_count += 1;
478 }
479
480 // We can reach here if we were unsuccessful in scheduling a
481 // collection (because another thread beat us to it) or if we were
482 // stalled due to the GC locker. In either can we should retry the
483 // allocation attempt in case another thread successfully
484 // performed a collection and reclaimed enough space. We do the
485 // first attempt (without holding the Heap_lock) here and the
486 // follow-on attempt will be at the start of the next loop
487 // iteration (after taking the Heap_lock).
488 size_t dummy = 0;
489 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
490 if (result != NULL) {
491 return result;
492 }
493
494 // Give a warning if we seem to be looping forever.
495 if ((QueuedAllocationWarningCount > 0) &&
496 (try_count % QueuedAllocationWarningCount == 0)) {
497 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
498 Thread::current()->name(), try_count, word_size);
499 }
500 }
501
502 ShouldNotReachHere();
503 return NULL;
504 }
505
506 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
507 assert_at_safepoint_on_vm_thread();
508 if (_archive_allocator == NULL) {
509 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
510 }
511 }
512
513 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
514 // Allocations in archive regions cannot be of a size that would be considered
515 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
516 // may be different at archive-restore time.
517 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
518 }
519
520 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
521 assert_at_safepoint_on_vm_thread();
522 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
523 if (is_archive_alloc_too_large(word_size)) {
524 return NULL;
525 }
526 return _archive_allocator->archive_mem_allocate(word_size);
527 }
528
529 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
530 size_t end_alignment_in_bytes) {
531 assert_at_safepoint_on_vm_thread();
532 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
533
534 // Call complete_archive to do the real work, filling in the MemRegion
535 // array with the archive regions.
536 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
537 delete _archive_allocator;
538 _archive_allocator = NULL;
539 }
540
541 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
542 assert(ranges != NULL, "MemRegion array NULL");
543 assert(count != 0, "No MemRegions provided");
544 MemRegion reserved = _hrm->reserved();
545 for (size_t i = 0; i < count; i++) {
546 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
547 return false;
548 }
549 }
550 return true;
551 }
552
553 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
554 size_t count,
555 bool open) {
556 assert(!is_init_completed(), "Expect to be called at JVM init time");
557 assert(ranges != NULL, "MemRegion array NULL");
558 assert(count != 0, "No MemRegions provided");
559 MutexLocker x(Heap_lock);
560
561 MemRegion reserved = _hrm->reserved();
562 HeapWord* prev_last_addr = NULL;
563 HeapRegion* prev_last_region = NULL;
564
565 // Temporarily disable pretouching of heap pages. This interface is used
566 // when mmap'ing archived heap data in, so pre-touching is wasted.
567 FlagSetting fs(AlwaysPreTouch, false);
568
569 // Enable archive object checking used by G1MarkSweep. We have to let it know
570 // about each archive range, so that objects in those ranges aren't marked.
571 G1ArchiveAllocator::enable_archive_object_check();
572
573 // For each specified MemRegion range, allocate the corresponding G1
574 // regions and mark them as archive regions. We expect the ranges
575 // in ascending starting address order, without overlap.
576 for (size_t i = 0; i < count; i++) {
577 MemRegion curr_range = ranges[i];
578 HeapWord* start_address = curr_range.start();
579 size_t word_size = curr_range.word_size();
580 HeapWord* last_address = curr_range.last();
581 size_t commits = 0;
582
583 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
584 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
585 p2i(start_address), p2i(last_address));
586 guarantee(start_address > prev_last_addr,
587 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
588 p2i(start_address), p2i(prev_last_addr));
589 prev_last_addr = last_address;
590
591 // Check for ranges that start in the same G1 region in which the previous
592 // range ended, and adjust the start address so we don't try to allocate
593 // the same region again. If the current range is entirely within that
594 // region, skip it, just adjusting the recorded top.
595 HeapRegion* start_region = _hrm->addr_to_region(start_address);
596 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
597 start_address = start_region->end();
598 if (start_address > last_address) {
599 increase_used(word_size * HeapWordSize);
600 start_region->set_top(last_address + 1);
601 continue;
602 }
603 start_region->set_top(start_address);
604 curr_range = MemRegion(start_address, last_address + 1);
605 start_region = _hrm->addr_to_region(start_address);
606 }
607
608 // Perform the actual region allocation, exiting if it fails.
609 // Then note how much new space we have allocated.
610 if (!_hrm->allocate_containing_regions(curr_range, &commits, workers())) {
611 return false;
612 }
613 increase_used(word_size * HeapWordSize);
614 if (commits != 0) {
615 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
616 HeapRegion::GrainWords * HeapWordSize * commits);
617
618 }
619
620 // Mark each G1 region touched by the range as archive, add it to
621 // the old set, and set top.
622 HeapRegion* curr_region = _hrm->addr_to_region(start_address);
623 HeapRegion* last_region = _hrm->addr_to_region(last_address);
624 prev_last_region = last_region;
625
626 while (curr_region != NULL) {
627 assert(curr_region->is_empty() && !curr_region->is_pinned(),
628 "Region already in use (index %u)", curr_region->hrm_index());
629 if (open) {
630 curr_region->set_open_archive();
631 } else {
632 curr_region->set_closed_archive();
633 }
634 _hr_printer.alloc(curr_region);
635 _archive_set.add(curr_region);
636 HeapWord* top;
637 HeapRegion* next_region;
638 if (curr_region != last_region) {
639 top = curr_region->end();
640 next_region = _hrm->next_region_in_heap(curr_region);
641 } else {
642 top = last_address + 1;
643 next_region = NULL;
644 }
645 curr_region->set_top(top);
646 curr_region = next_region;
647 }
648
649 // Notify mark-sweep of the archive
650 G1ArchiveAllocator::set_range_archive(curr_range, open);
651 }
652 return true;
653 }
654
655 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
656 assert(!is_init_completed(), "Expect to be called at JVM init time");
657 assert(ranges != NULL, "MemRegion array NULL");
658 assert(count != 0, "No MemRegions provided");
659 MemRegion reserved = _hrm->reserved();
660 HeapWord *prev_last_addr = NULL;
661 HeapRegion* prev_last_region = NULL;
662
663 // For each MemRegion, create filler objects, if needed, in the G1 regions
664 // that contain the address range. The address range actually within the
665 // MemRegion will not be modified. That is assumed to have been initialized
666 // elsewhere, probably via an mmap of archived heap data.
667 MutexLocker x(Heap_lock);
668 for (size_t i = 0; i < count; i++) {
669 HeapWord* start_address = ranges[i].start();
670 HeapWord* last_address = ranges[i].last();
671
672 assert(reserved.contains(start_address) && reserved.contains(last_address),
673 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
674 p2i(start_address), p2i(last_address));
675 assert(start_address > prev_last_addr,
676 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
677 p2i(start_address), p2i(prev_last_addr));
678
679 HeapRegion* start_region = _hrm->addr_to_region(start_address);
680 HeapRegion* last_region = _hrm->addr_to_region(last_address);
681 HeapWord* bottom_address = start_region->bottom();
682
683 // Check for a range beginning in the same region in which the
684 // previous one ended.
685 if (start_region == prev_last_region) {
686 bottom_address = prev_last_addr + 1;
687 }
688
689 // Verify that the regions were all marked as archive regions by
690 // alloc_archive_regions.
691 HeapRegion* curr_region = start_region;
692 while (curr_region != NULL) {
693 guarantee(curr_region->is_archive(),
694 "Expected archive region at index %u", curr_region->hrm_index());
695 if (curr_region != last_region) {
696 curr_region = _hrm->next_region_in_heap(curr_region);
697 } else {
698 curr_region = NULL;
699 }
700 }
701
702 prev_last_addr = last_address;
703 prev_last_region = last_region;
704
705 // Fill the memory below the allocated range with dummy object(s),
706 // if the region bottom does not match the range start, or if the previous
707 // range ended within the same G1 region, and there is a gap.
708 if (start_address != bottom_address) {
709 size_t fill_size = pointer_delta(start_address, bottom_address);
710 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
711 increase_used(fill_size * HeapWordSize);
712 }
713 }
714 }
715
716 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
717 size_t desired_word_size,
718 size_t* actual_word_size) {
719 assert_heap_not_locked_and_not_at_safepoint();
720 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
721 "be called for humongous allocation requests");
722
723 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
724
725 if (result == NULL) {
726 *actual_word_size = desired_word_size;
727 result = attempt_allocation_slow(desired_word_size);
728 }
729
730 assert_heap_not_locked();
731 if (result != NULL) {
732 assert(*actual_word_size != 0, "Actual size must have been set here");
733 dirty_young_block(result, *actual_word_size);
734 } else {
735 *actual_word_size = 0;
736 }
737
738 return result;
739 }
740
741 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
742 assert(!is_init_completed(), "Expect to be called at JVM init time");
743 assert(ranges != NULL, "MemRegion array NULL");
744 assert(count != 0, "No MemRegions provided");
745 MemRegion reserved = _hrm->reserved();
746 HeapWord* prev_last_addr = NULL;
747 HeapRegion* prev_last_region = NULL;
748 size_t size_used = 0;
749 size_t uncommitted_regions = 0;
750
751 // For each Memregion, free the G1 regions that constitute it, and
752 // notify mark-sweep that the range is no longer to be considered 'archive.'
753 MutexLocker x(Heap_lock);
754 for (size_t i = 0; i < count; i++) {
755 HeapWord* start_address = ranges[i].start();
756 HeapWord* last_address = ranges[i].last();
757
758 assert(reserved.contains(start_address) && reserved.contains(last_address),
759 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
760 p2i(start_address), p2i(last_address));
761 assert(start_address > prev_last_addr,
762 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
763 p2i(start_address), p2i(prev_last_addr));
764 size_used += ranges[i].byte_size();
765 prev_last_addr = last_address;
766
767 HeapRegion* start_region = _hrm->addr_to_region(start_address);
768 HeapRegion* last_region = _hrm->addr_to_region(last_address);
769
770 // Check for ranges that start in the same G1 region in which the previous
771 // range ended, and adjust the start address so we don't try to free
772 // the same region again. If the current range is entirely within that
773 // region, skip it.
774 if (start_region == prev_last_region) {
775 start_address = start_region->end();
776 if (start_address > last_address) {
777 continue;
778 }
779 start_region = _hrm->addr_to_region(start_address);
780 }
781 prev_last_region = last_region;
782
783 // After verifying that each region was marked as an archive region by
784 // alloc_archive_regions, set it free and empty and uncommit it.
785 HeapRegion* curr_region = start_region;
786 while (curr_region != NULL) {
787 guarantee(curr_region->is_archive(),
788 "Expected archive region at index %u", curr_region->hrm_index());
789 uint curr_index = curr_region->hrm_index();
790 _archive_set.remove(curr_region);
791 curr_region->set_free();
792 curr_region->set_top(curr_region->bottom());
793 if (curr_region != last_region) {
794 curr_region = _hrm->next_region_in_heap(curr_region);
795 } else {
796 curr_region = NULL;
797 }
798 _hrm->shrink_at(curr_index, 1);
799 uncommitted_regions++;
800 }
801
802 // Notify mark-sweep that this is no longer an archive range.
803 G1ArchiveAllocator::clear_range_archive(ranges[i]);
804 }
805
806 if (uncommitted_regions != 0) {
807 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
808 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
809 }
810 decrease_used(size_used);
811 }
812
813 oop G1CollectedHeap::materialize_archived_object(oop obj) {
814 assert(obj != NULL, "archived obj is NULL");
815 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
816
817 // Loading an archived object makes it strongly reachable. If it is
818 // loaded during concurrent marking, it must be enqueued to the SATB
819 // queue, shading the previously white object gray.
820 G1BarrierSet::enqueue(obj);
821
822 return obj;
823 }
824
825 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
826 ResourceMark rm; // For retrieving the thread names in log messages.
827
828 // The structure of this method has a lot of similarities to
829 // attempt_allocation_slow(). The reason these two were not merged
830 // into a single one is that such a method would require several "if
831 // allocation is not humongous do this, otherwise do that"
832 // conditional paths which would obscure its flow. In fact, an early
833 // version of this code did use a unified method which was harder to
834 // follow and, as a result, it had subtle bugs that were hard to
835 // track down. So keeping these two methods separate allows each to
836 // be more readable. It will be good to keep these two in sync as
837 // much as possible.
838
839 assert_heap_not_locked_and_not_at_safepoint();
840 assert(is_humongous(word_size), "attempt_allocation_humongous() "
841 "should only be called for humongous allocations");
842
843 // Humongous objects can exhaust the heap quickly, so we should check if we
844 // need to start a marking cycle at each humongous object allocation. We do
845 // the check before we do the actual allocation. The reason for doing it
846 // before the allocation is that we avoid having to keep track of the newly
847 // allocated memory while we do a GC.
848 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
849 word_size)) {
850 collect(GCCause::_g1_humongous_allocation);
851 }
852
853 // We will loop until a) we manage to successfully perform the
854 // allocation or b) we successfully schedule a collection which
855 // fails to perform the allocation. b) is the only case when we'll
856 // return NULL.
857 HeapWord* result = NULL;
858 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
859 bool should_try_gc;
860 uint gc_count_before;
861
862
863 {
864 MutexLocker x(Heap_lock);
865
866 // Given that humongous objects are not allocated in young
867 // regions, we'll first try to do the allocation without doing a
868 // collection hoping that there's enough space in the heap.
869 result = humongous_obj_allocate(word_size);
870 if (result != NULL) {
871 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
872 policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
873 return result;
874 }
875
876 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
877 // the GCLocker initiated GC has been performed and then retry. This includes
878 // the case when the GC Locker is not active but has not been performed.
879 should_try_gc = !GCLocker::needs_gc();
880 // Read the GC count while still holding the Heap_lock.
881 gc_count_before = total_collections();
882 }
883
884 if (should_try_gc) {
885 bool succeeded;
886 result = do_collection_pause(word_size, gc_count_before, &succeeded,
887 GCCause::_g1_humongous_allocation);
888 if (result != NULL) {
889 assert(succeeded, "only way to get back a non-NULL result");
890 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
891 Thread::current()->name(), p2i(result));
892 return result;
893 }
894
895 if (succeeded) {
896 // We successfully scheduled a collection which failed to allocate. No
897 // point in trying to allocate further. We'll just return NULL.
898 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
899 SIZE_FORMAT " words", Thread::current()->name(), word_size);
900 return NULL;
901 }
902 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
903 Thread::current()->name(), word_size);
904 } else {
905 // Failed to schedule a collection.
906 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
907 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
908 SIZE_FORMAT " words", Thread::current()->name(), word_size);
909 return NULL;
910 }
911 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
912 // The GCLocker is either active or the GCLocker initiated
913 // GC has not yet been performed. Stall until it is and
914 // then retry the allocation.
915 GCLocker::stall_until_clear();
916 gclocker_retry_count += 1;
917 }
918
919
920 // We can reach here if we were unsuccessful in scheduling a
921 // collection (because another thread beat us to it) or if we were
922 // stalled due to the GC locker. In either can we should retry the
923 // allocation attempt in case another thread successfully
924 // performed a collection and reclaimed enough space.
925 // Humongous object allocation always needs a lock, so we wait for the retry
926 // in the next iteration of the loop, unlike for the regular iteration case.
927 // Give a warning if we seem to be looping forever.
928
929 if ((QueuedAllocationWarningCount > 0) &&
930 (try_count % QueuedAllocationWarningCount == 0)) {
931 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
932 Thread::current()->name(), try_count, word_size);
933 }
934 }
935
936 ShouldNotReachHere();
937 return NULL;
938 }
939
940 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
941 bool expect_null_mutator_alloc_region) {
942 assert_at_safepoint_on_vm_thread();
943 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
944 "the current alloc region was unexpectedly found to be non-NULL");
945
946 if (!is_humongous(word_size)) {
947 return _allocator->attempt_allocation_locked(word_size);
948 } else {
949 HeapWord* result = humongous_obj_allocate(word_size);
950 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
951 collector_state()->set_initiate_conc_mark_if_possible(true);
952 }
953 return result;
954 }
955
956 ShouldNotReachHere();
957 }
958
959 class PostCompactionPrinterClosure: public HeapRegionClosure {
960 private:
961 G1HRPrinter* _hr_printer;
962 public:
963 bool do_heap_region(HeapRegion* hr) {
964 assert(!hr->is_young(), "not expecting to find young regions");
965 _hr_printer->post_compaction(hr);
966 return false;
967 }
968
969 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
970 : _hr_printer(hr_printer) { }
971 };
972
973 void G1CollectedHeap::print_hrm_post_compaction() {
974 if (_hr_printer.is_active()) {
975 PostCompactionPrinterClosure cl(hr_printer());
976 heap_region_iterate(&cl);
977 }
978 }
979
980 void G1CollectedHeap::abort_concurrent_cycle() {
981 // If we start the compaction before the CM threads finish
982 // scanning the root regions we might trip them over as we'll
983 // be moving objects / updating references. So let's wait until
984 // they are done. By telling them to abort, they should complete
985 // early.
986 _cm->root_regions()->abort();
987 _cm->root_regions()->wait_until_scan_finished();
988
989 // Disable discovery and empty the discovered lists
990 // for the CM ref processor.
991 _ref_processor_cm->disable_discovery();
992 _ref_processor_cm->abandon_partial_discovery();
993 _ref_processor_cm->verify_no_references_recorded();
994
995 // Abandon current iterations of concurrent marking and concurrent
996 // refinement, if any are in progress.
997 concurrent_mark()->concurrent_cycle_abort();
998 }
999
1000 void G1CollectedHeap::prepare_heap_for_full_collection() {
1001 // Make sure we'll choose a new allocation region afterwards.
1002 _allocator->release_mutator_alloc_regions();
1003 _allocator->abandon_gc_alloc_regions();
1004
1005 // We may have added regions to the current incremental collection
1006 // set between the last GC or pause and now. We need to clear the
1007 // incremental collection set and then start rebuilding it afresh
1008 // after this full GC.
1009 abandon_collection_set(collection_set());
1010
1011 tear_down_region_sets(false /* free_list_only */);
1012
1013 hrm()->prepare_for_full_collection_start();
1014 }
1015
1016 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1017 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1018 assert_used_and_recalculate_used_equal(this);
1019 _verifier->verify_region_sets_optional();
1020 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1021 _verifier->check_bitmaps("Full GC Start");
1022 }
1023
1024 void G1CollectedHeap::prepare_heap_for_mutators() {
1025 hrm()->prepare_for_full_collection_end();
1026
1027 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1028 ClassLoaderDataGraph::purge();
1029 MetaspaceUtils::verify_metrics();
1030
1031 // Prepare heap for normal collections.
1032 assert(num_free_regions() == 0, "we should not have added any free regions");
1033 rebuild_region_sets(false /* free_list_only */);
1034 abort_refinement();
1035 resize_heap_if_necessary();
1036
1037 // Rebuild the strong code root lists for each region
1038 rebuild_strong_code_roots();
1039
1040 // Purge code root memory
1041 purge_code_root_memory();
1042
1043 // Start a new incremental collection set for the next pause
1044 start_new_collection_set();
1045
1046 _allocator->init_mutator_alloc_regions();
1047
1048 // Post collection state updates.
1049 MetaspaceGC::compute_new_size();
1050 }
1051
1052 void G1CollectedHeap::abort_refinement() {
1053 if (_hot_card_cache->use_cache()) {
1054 _hot_card_cache->reset_hot_cache();
1055 }
1056
1057 // Discard all remembered set updates and reset refinement statistics.
1058 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1059 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1060 "DCQS should be empty");
1061 concurrent_refine()->get_and_reset_refinement_stats();
1062 }
1063
1064 void G1CollectedHeap::verify_after_full_collection() {
1065 _hrm->verify_optional();
1066 _verifier->verify_region_sets_optional();
1067 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1068 // Clear the previous marking bitmap, if needed for bitmap verification.
1069 // Note we cannot do this when we clear the next marking bitmap in
1070 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1071 // objects marked during a full GC against the previous bitmap.
1072 // But we need to clear it before calling check_bitmaps below since
1073 // the full GC has compacted objects and updated TAMS but not updated
1074 // the prev bitmap.
1075 if (G1VerifyBitmaps) {
1076 GCTraceTime(Debug, gc) tm("Clear Prev Bitmap for Verification");
1077 _cm->clear_prev_bitmap(workers());
1078 }
1079 // This call implicitly verifies that the next bitmap is clear after Full GC.
1080 _verifier->check_bitmaps("Full GC End");
1081
1082 // At this point there should be no regions in the
1083 // entire heap tagged as young.
1084 assert(check_young_list_empty(), "young list should be empty at this point");
1085
1086 // Note: since we've just done a full GC, concurrent
1087 // marking is no longer active. Therefore we need not
1088 // re-enable reference discovery for the CM ref processor.
1089 // That will be done at the start of the next marking cycle.
1090 // We also know that the STW processor should no longer
1091 // discover any new references.
1092 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1093 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1094 _ref_processor_stw->verify_no_references_recorded();
1095 _ref_processor_cm->verify_no_references_recorded();
1096 }
1097
1098 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1099 // Post collection logging.
1100 // We should do this after we potentially resize the heap so
1101 // that all the COMMIT / UNCOMMIT events are generated before
1102 // the compaction events.
1103 print_hrm_post_compaction();
1104 heap_transition->print();
1105 print_heap_after_gc();
1106 print_heap_regions();
1107 }
1108
1109 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1110 bool clear_all_soft_refs) {
1111 assert_at_safepoint_on_vm_thread();
1112
1113 if (GCLocker::check_active_before_gc()) {
1114 // Full GC was not completed.
1115 return false;
1116 }
1117
1118 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1119 soft_ref_policy()->should_clear_all_soft_refs();
1120
1121 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1122 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1123
1124 collector.prepare_collection();
1125 collector.collect();
1126 collector.complete_collection();
1127
1128 // Full collection was successfully completed.
1129 return true;
1130 }
1131
1132 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1133 // Currently, there is no facility in the do_full_collection(bool) API to notify
1134 // the caller that the collection did not succeed (e.g., because it was locked
1135 // out by the GC locker). So, right now, we'll ignore the return value.
1136 bool dummy = do_full_collection(true, /* explicit_gc */
1137 clear_all_soft_refs);
1138 }
1139
1140 void G1CollectedHeap::resize_heap_if_necessary() {
1141 assert_at_safepoint_on_vm_thread();
1142
1143 // Capacity, free and used after the GC counted as full regions to
1144 // include the waste in the following calculations.
1145 const size_t capacity_after_gc = capacity();
1146 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1147
1148 // This is enforced in arguments.cpp.
1149 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1150 "otherwise the code below doesn't make sense");
1151
1152 // We don't have floating point command-line arguments
1153 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1154 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1155 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1156 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1157
1158 // We have to be careful here as these two calculations can overflow
1159 // 32-bit size_t's.
1160 double used_after_gc_d = (double) used_after_gc;
1161 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1162 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1163
1164 // Let's make sure that they are both under the max heap size, which
1165 // by default will make them fit into a size_t.
1166 double desired_capacity_upper_bound = (double) MaxHeapSize;
1167 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1168 desired_capacity_upper_bound);
1169 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1170 desired_capacity_upper_bound);
1171
1172 // We can now safely turn them into size_t's.
1173 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1174 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1175
1176 // This assert only makes sense here, before we adjust them
1177 // with respect to the min and max heap size.
1178 assert(minimum_desired_capacity <= maximum_desired_capacity,
1179 "minimum_desired_capacity = " SIZE_FORMAT ", "
1180 "maximum_desired_capacity = " SIZE_FORMAT,
1181 minimum_desired_capacity, maximum_desired_capacity);
1182
1183 // Should not be greater than the heap max size. No need to adjust
1184 // it with respect to the heap min size as it's a lower bound (i.e.,
1185 // we'll try to make the capacity larger than it, not smaller).
1186 minimum_desired_capacity = MIN2(minimum_desired_capacity, MaxHeapSize);
1187 // Should not be less than the heap min size. No need to adjust it
1188 // with respect to the heap max size as it's an upper bound (i.e.,
1189 // we'll try to make the capacity smaller than it, not greater).
1190 maximum_desired_capacity = MAX2(maximum_desired_capacity, MinHeapSize);
1191
1192 if (capacity_after_gc < minimum_desired_capacity) {
1193 // Don't expand unless it's significant
1194 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1195
1196 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1197 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1198 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1199 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1200
1201 expand(expand_bytes, _workers);
1202
1203 // No expansion, now see if we want to shrink
1204 } else if (capacity_after_gc > maximum_desired_capacity) {
1205 // Capacity too large, compute shrinking size
1206 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1207
1208 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1209 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1210 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1211 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1212
1213 shrink(shrink_bytes);
1214 }
1215 }
1216
1217 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1218 bool do_gc,
1219 bool clear_all_soft_refs,
1220 bool expect_null_mutator_alloc_region,
1221 bool* gc_succeeded) {
1222 *gc_succeeded = true;
1223 // Let's attempt the allocation first.
1224 HeapWord* result =
1225 attempt_allocation_at_safepoint(word_size,
1226 expect_null_mutator_alloc_region);
1227 if (result != NULL) {
1228 return result;
1229 }
1230
1231 // In a G1 heap, we're supposed to keep allocation from failing by
1232 // incremental pauses. Therefore, at least for now, we'll favor
1233 // expansion over collection. (This might change in the future if we can
1234 // do something smarter than full collection to satisfy a failed alloc.)
1235 result = expand_and_allocate(word_size);
1236 if (result != NULL) {
1237 return result;
1238 }
1239
1240 if (do_gc) {
1241 // Expansion didn't work, we'll try to do a Full GC.
1242 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1243 clear_all_soft_refs);
1244 }
1245
1246 return NULL;
1247 }
1248
1249 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1250 bool* succeeded) {
1251 assert_at_safepoint_on_vm_thread();
1252
1253 // Attempts to allocate followed by Full GC.
1254 HeapWord* result =
1255 satisfy_failed_allocation_helper(word_size,
1256 true, /* do_gc */
1257 false, /* clear_all_soft_refs */
1258 false, /* expect_null_mutator_alloc_region */
1259 succeeded);
1260
1261 if (result != NULL || !*succeeded) {
1262 return result;
1263 }
1264
1265 // Attempts to allocate followed by Full GC that will collect all soft references.
1266 result = satisfy_failed_allocation_helper(word_size,
1267 true, /* do_gc */
1268 true, /* clear_all_soft_refs */
1269 true, /* expect_null_mutator_alloc_region */
1270 succeeded);
1271
1272 if (result != NULL || !*succeeded) {
1273 return result;
1274 }
1275
1276 // Attempts to allocate, no GC
1277 result = satisfy_failed_allocation_helper(word_size,
1278 false, /* do_gc */
1279 false, /* clear_all_soft_refs */
1280 true, /* expect_null_mutator_alloc_region */
1281 succeeded);
1282
1283 if (result != NULL) {
1284 return result;
1285 }
1286
1287 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1288 "Flag should have been handled and cleared prior to this point");
1289
1290 // What else? We might try synchronous finalization later. If the total
1291 // space available is large enough for the allocation, then a more
1292 // complete compaction phase than we've tried so far might be
1293 // appropriate.
1294 return NULL;
1295 }
1296
1297 // Attempting to expand the heap sufficiently
1298 // to support an allocation of the given "word_size". If
1299 // successful, perform the allocation and return the address of the
1300 // allocated block, or else "NULL".
1301
1302 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1303 assert_at_safepoint_on_vm_thread();
1304
1305 _verifier->verify_region_sets_optional();
1306
1307 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1308 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1309 word_size * HeapWordSize);
1310
1311
1312 if (expand(expand_bytes, _workers)) {
1313 _hrm->verify_optional();
1314 _verifier->verify_region_sets_optional();
1315 return attempt_allocation_at_safepoint(word_size,
1316 false /* expect_null_mutator_alloc_region */);
1317 }
1318 return NULL;
1319 }
1320
1321 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1322 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1323 aligned_expand_bytes = align_up(aligned_expand_bytes,
1324 HeapRegion::GrainBytes);
1325
1326 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1327 expand_bytes, aligned_expand_bytes);
1328
1329 if (is_maximal_no_gc()) {
1330 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1331 return false;
1332 }
1333
1334 double expand_heap_start_time_sec = os::elapsedTime();
1335 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1336 assert(regions_to_expand > 0, "Must expand by at least one region");
1337
1338 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1339 if (expand_time_ms != NULL) {
1340 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1341 }
1342
1343 if (expanded_by > 0) {
1344 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1345 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1346 policy()->record_new_heap_size(num_regions());
1347 } else {
1348 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1349
1350 // The expansion of the virtual storage space was unsuccessful.
1351 // Let's see if it was because we ran out of swap.
1352 if (G1ExitOnExpansionFailure &&
1353 _hrm->available() >= regions_to_expand) {
1354 // We had head room...
1355 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1356 }
1357 }
1358 return regions_to_expand > 0;
1359 }
1360
1361 bool G1CollectedHeap::expand_single_region(uint node_index) {
1362 uint expanded_by = _hrm->expand_on_preferred_node(node_index);
1363
1364 if (expanded_by == 0) {
1365 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm->available());
1366 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1367 return false;
1368 }
1369
1370 policy()->record_new_heap_size(num_regions());
1371 return true;
1372 }
1373
1374 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1375 size_t aligned_shrink_bytes =
1376 ReservedSpace::page_align_size_down(shrink_bytes);
1377 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1378 HeapRegion::GrainBytes);
1379 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1380
1381 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1382 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1383
1384 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",
1385 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1386 if (num_regions_removed > 0) {
1387 policy()->record_new_heap_size(num_regions());
1388 } else {
1389 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1390 }
1391 }
1392
1393 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1394 _verifier->verify_region_sets_optional();
1395
1396 // We should only reach here at the end of a Full GC or during Remark which
1397 // means we should not not be holding to any GC alloc regions. The method
1398 // below will make sure of that and do any remaining clean up.
1399 _allocator->abandon_gc_alloc_regions();
1400
1401 // Instead of tearing down / rebuilding the free lists here, we
1402 // could instead use the remove_all_pending() method on free_list to
1403 // remove only the ones that we need to remove.
1404 tear_down_region_sets(true /* free_list_only */);
1405 shrink_helper(shrink_bytes);
1406 rebuild_region_sets(true /* free_list_only */);
1407
1408 _hrm->verify_optional();
1409 _verifier->verify_region_sets_optional();
1410 }
1411
1412 class OldRegionSetChecker : public HeapRegionSetChecker {
1413 public:
1414 void check_mt_safety() {
1415 // Master Old Set MT safety protocol:
1416 // (a) If we're at a safepoint, operations on the master old set
1417 // should be invoked:
1418 // - by the VM thread (which will serialize them), or
1419 // - by the GC workers while holding the FreeList_lock, if we're
1420 // at a safepoint for an evacuation pause (this lock is taken
1421 // anyway when an GC alloc region is retired so that a new one
1422 // is allocated from the free list), or
1423 // - by the GC workers while holding the OldSets_lock, if we're at a
1424 // safepoint for a cleanup pause.
1425 // (b) If we're not at a safepoint, operations on the master old set
1426 // should be invoked while holding the Heap_lock.
1427
1428 if (SafepointSynchronize::is_at_safepoint()) {
1429 guarantee(Thread::current()->is_VM_thread() ||
1430 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1431 "master old set MT safety protocol at a safepoint");
1432 } else {
1433 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1434 }
1435 }
1436 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1437 const char* get_description() { return "Old Regions"; }
1438 };
1439
1440 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1441 public:
1442 void check_mt_safety() {
1443 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1444 "May only change archive regions during initialization or safepoint.");
1445 }
1446 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1447 const char* get_description() { return "Archive Regions"; }
1448 };
1449
1450 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1451 public:
1452 void check_mt_safety() {
1453 // Humongous Set MT safety protocol:
1454 // (a) If we're at a safepoint, operations on the master humongous
1455 // set should be invoked by either the VM thread (which will
1456 // serialize them) or by the GC workers while holding the
1457 // OldSets_lock.
1458 // (b) If we're not at a safepoint, operations on the master
1459 // humongous set should be invoked while holding the Heap_lock.
1460
1461 if (SafepointSynchronize::is_at_safepoint()) {
1462 guarantee(Thread::current()->is_VM_thread() ||
1463 OldSets_lock->owned_by_self(),
1464 "master humongous set MT safety protocol at a safepoint");
1465 } else {
1466 guarantee(Heap_lock->owned_by_self(),
1467 "master humongous set MT safety protocol outside a safepoint");
1468 }
1469 }
1470 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1471 const char* get_description() { return "Humongous Regions"; }
1472 };
1473
1474 G1CollectedHeap::G1CollectedHeap() :
1475 CollectedHeap(),
1476 _young_gen_sampling_thread(NULL),
1477 _workers(NULL),
1478 _card_table(NULL),
1479 _soft_ref_policy(),
1480 _old_set("Old Region Set", new OldRegionSetChecker()),
1481 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1482 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1483 _bot(NULL),
1484 _listener(),
1485 _numa(G1NUMA::create()),
1486 _hrm(NULL),
1487 _allocator(NULL),
1488 _verifier(NULL),
1489 _summary_bytes_used(0),
1490 _bytes_used_during_gc(0),
1491 _archive_allocator(NULL),
1492 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1493 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1494 _expand_heap_after_alloc_failure(true),
1495 _g1mm(NULL),
1496 _humongous_reclaim_candidates(),
1497 _has_humongous_reclaim_candidates(false),
1498 _hr_printer(),
1499 _collector_state(),
1500 _old_marking_cycles_started(0),
1501 _old_marking_cycles_completed(0),
1502 _eden(),
1503 _survivor(),
1504 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1505 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1506 _policy(G1Policy::create_policy(_gc_timer_stw)),
1507 _heap_sizing_policy(NULL),
1508 _collection_set(this, _policy),
1509 _hot_card_cache(NULL),
1510 _rem_set(NULL),
1511 _cm(NULL),
1512 _cm_thread(NULL),
1513 _cr(NULL),
1514 _task_queues(NULL),
1515 _evacuation_failed(false),
1516 _evacuation_failed_info_array(NULL),
1517 _preserved_marks_set(true /* in_c_heap */),
1518 #ifndef PRODUCT
1519 _evacuation_failure_alot_for_current_gc(false),
1520 _evacuation_failure_alot_gc_number(0),
1521 _evacuation_failure_alot_count(0),
1522 #endif
1523 _ref_processor_stw(NULL),
1524 _is_alive_closure_stw(this),
1525 _is_subject_to_discovery_stw(this),
1526 _ref_processor_cm(NULL),
1527 _is_alive_closure_cm(this),
1528 _is_subject_to_discovery_cm(this),
1529 _region_attr() {
1530
1531 _verifier = new G1HeapVerifier(this);
1532
1533 _allocator = new G1Allocator(this);
1534
1535 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1536
1537 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1538
1539 // Override the default _filler_array_max_size so that no humongous filler
1540 // objects are created.
1541 _filler_array_max_size = _humongous_object_threshold_in_words;
1542
1543 uint n_queues = ParallelGCThreads;
1544 _task_queues = new ScannerTasksQueueSet(n_queues);
1545
1546 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1547
1548 for (uint i = 0; i < n_queues; i++) {
1549 ScannerTasksQueue* q = new ScannerTasksQueue();
1550 q->initialize();
1551 _task_queues->register_queue(i, q);
1552 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1553 }
1554
1555 // Initialize the G1EvacuationFailureALot counters and flags.
1556 NOT_PRODUCT(reset_evacuation_should_fail();)
1557 _gc_tracer_stw->initialize();
1558
1559 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1560 }
1561
1562 static size_t actual_reserved_page_size(ReservedSpace rs) {
1563 size_t page_size = os::vm_page_size();
1564 if (UseLargePages) {
1565 // There are two ways to manage large page memory.
1566 // 1. OS supports committing large page memory.
1567 // 2. OS doesn't support committing large page memory so ReservedSpace manages it.
1568 // And ReservedSpace calls it 'special'. If we failed to set 'special',
1569 // we reserved memory without large page.
1570 if (os::can_commit_large_page_memory() || rs.special()) {
1571 // An alignment at ReservedSpace comes from preferred page size or
1572 // heap alignment, and if the alignment came from heap alignment, it could be
1573 // larger than large pages size. So need to cap with the large page size.
1574 page_size = MIN2(rs.alignment(), os::large_page_size());
1575 }
1576 }
1577
1578 return page_size;
1579 }
1580
1581 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1582 size_t size,
1583 size_t translation_factor) {
1584 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1585 // Allocate a new reserved space, preferring to use large pages.
1586 ReservedSpace rs(size, preferred_page_size);
1587 size_t page_size = actual_reserved_page_size(rs);
1588 G1RegionToSpaceMapper* result =
1589 G1RegionToSpaceMapper::create_mapper(rs,
1590 size,
1591 page_size,
1592 HeapRegion::GrainBytes,
1593 translation_factor,
1594 mtGC);
1595
1596 os::trace_page_sizes_for_requested_size(description,
1597 size,
1598 preferred_page_size,
1599 page_size,
1600 rs.base(),
1601 rs.size());
1602
1603 return result;
1604 }
1605
1606 jint G1CollectedHeap::initialize_concurrent_refinement() {
1607 jint ecode = JNI_OK;
1608 _cr = G1ConcurrentRefine::create(&ecode);
1609 return ecode;
1610 }
1611
1612 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1613 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1614 if (_young_gen_sampling_thread->osthread() == NULL) {
1615 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1616 return JNI_ENOMEM;
1617 }
1618 return JNI_OK;
1619 }
1620
1621 jint G1CollectedHeap::initialize() {
1622
1623 // Necessary to satisfy locking discipline assertions.
1624
1625 MutexLocker x(Heap_lock);
1626
1627 // While there are no constraints in the GC code that HeapWordSize
1628 // be any particular value, there are multiple other areas in the
1629 // system which believe this to be true (e.g. oop->object_size in some
1630 // cases incorrectly returns the size in wordSize units rather than
1631 // HeapWordSize).
1632 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1633
1634 size_t init_byte_size = InitialHeapSize;
1635 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1636
1637 // Ensure that the sizes are properly aligned.
1638 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1639 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1640 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1641
1642 // Reserve the maximum.
1643
1644 // When compressed oops are enabled, the preferred heap base
1645 // is calculated by subtracting the requested size from the
1646 // 32Gb boundary and using the result as the base address for
1647 // heap reservation. If the requested size is not aligned to
1648 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1649 // into the ReservedHeapSpace constructor) then the actual
1650 // base of the reserved heap may end up differing from the
1651 // address that was requested (i.e. the preferred heap base).
1652 // If this happens then we could end up using a non-optimal
1653 // compressed oops mode.
1654
1655 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1656 HeapAlignment);
1657
1658 initialize_reserved_region(heap_rs);
1659
1660 // Create the barrier set for the entire reserved region.
1661 G1CardTable* ct = new G1CardTable(heap_rs.region());
1662 ct->initialize();
1663 G1BarrierSet* bs = new G1BarrierSet(ct);
1664 bs->initialize();
1665 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1666 BarrierSet::set_barrier_set(bs);
1667 _card_table = ct;
1668
1669 {
1670 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1671 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1672 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1673 }
1674
1675 // Create the hot card cache.
1676 _hot_card_cache = new G1HotCardCache(this);
1677
1678 // Carve out the G1 part of the heap.
1679 ReservedSpace g1_rs = heap_rs.first_part(reserved_byte_size);
1680 size_t page_size = actual_reserved_page_size(heap_rs);
1681 G1RegionToSpaceMapper* heap_storage =
1682 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1683 g1_rs.size(),
1684 page_size,
1685 HeapRegion::GrainBytes,
1686 1,
1687 mtJavaHeap);
1688 if(heap_storage == NULL) {
1689 vm_shutdown_during_initialization("Could not initialize G1 heap");
1690 return JNI_ERR;
1691 }
1692
1693 os::trace_page_sizes("Heap",
1694 MinHeapSize,
1695 reserved_byte_size,
1696 page_size,
1697 heap_rs.base(),
1698 heap_rs.size());
1699 heap_storage->set_mapping_changed_listener(&_listener);
1700
1701 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1702 G1RegionToSpaceMapper* bot_storage =
1703 create_aux_memory_mapper("Block Offset Table",
1704 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1705 G1BlockOffsetTable::heap_map_factor());
1706
1707 G1RegionToSpaceMapper* cardtable_storage =
1708 create_aux_memory_mapper("Card Table",
1709 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1710 G1CardTable::heap_map_factor());
1711
1712 G1RegionToSpaceMapper* card_counts_storage =
1713 create_aux_memory_mapper("Card Counts Table",
1714 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1715 G1CardCounts::heap_map_factor());
1716
1717 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1718 G1RegionToSpaceMapper* prev_bitmap_storage =
1719 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1720 G1RegionToSpaceMapper* next_bitmap_storage =
1721 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1722
1723 _hrm = HeapRegionManager::create_manager(this);
1724
1725 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1726 _card_table->initialize(cardtable_storage);
1727
1728 // Do later initialization work for concurrent refinement.
1729 _hot_card_cache->initialize(card_counts_storage);
1730
1731 // 6843694 - ensure that the maximum region index can fit
1732 // in the remembered set structures.
1733 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1734 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1735
1736 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1737 // start within the first card.
1738 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1739 // Also create a G1 rem set.
1740 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1741 _rem_set->initialize(max_reserved_capacity(), max_regions());
1742
1743 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1744 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1745 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1746 "too many cards per region");
1747
1748 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1749
1750 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1751
1752 {
1753 HeapWord* start = _hrm->reserved().start();
1754 HeapWord* end = _hrm->reserved().end();
1755 size_t granularity = HeapRegion::GrainBytes;
1756
1757 _region_attr.initialize(start, end, granularity);
1758 _humongous_reclaim_candidates.initialize(start, end, granularity);
1759 }
1760
1761 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1762 true /* are_GC_task_threads */,
1763 false /* are_ConcurrentGC_threads */);
1764 if (_workers == NULL) {
1765 return JNI_ENOMEM;
1766 }
1767 _workers->initialize_workers();
1768
1769 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1770
1771 // Create the G1ConcurrentMark data structure and thread.
1772 // (Must do this late, so that "max_regions" is defined.)
1773 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1774 _cm_thread = _cm->cm_thread();
1775
1776 // Now expand into the initial heap size.
1777 if (!expand(init_byte_size, _workers)) {
1778 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1779 return JNI_ENOMEM;
1780 }
1781
1782 // Perform any initialization actions delegated to the policy.
1783 policy()->init(this, &_collection_set);
1784
1785 jint ecode = initialize_concurrent_refinement();
1786 if (ecode != JNI_OK) {
1787 return ecode;
1788 }
1789
1790 ecode = initialize_young_gen_sampling_thread();
1791 if (ecode != JNI_OK) {
1792 return ecode;
1793 }
1794
1795 {
1796 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1797 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1798 dcqs.set_max_cards(concurrent_refine()->red_zone());
1799 }
1800
1801 // Here we allocate the dummy HeapRegion that is required by the
1802 // G1AllocRegion class.
1803 HeapRegion* dummy_region = _hrm->get_dummy_region();
1804
1805 // We'll re-use the same region whether the alloc region will
1806 // require BOT updates or not and, if it doesn't, then a non-young
1807 // region will complain that it cannot support allocations without
1808 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1809 dummy_region->set_eden();
1810 // Make sure it's full.
1811 dummy_region->set_top(dummy_region->end());
1812 G1AllocRegion::setup(this, dummy_region);
1813
1814 _allocator->init_mutator_alloc_regions();
1815
1816 // Do create of the monitoring and management support so that
1817 // values in the heap have been properly initialized.
1818 _g1mm = new G1MonitoringSupport(this);
1819
1820 G1StringDedup::initialize();
1821
1822 _preserved_marks_set.init(ParallelGCThreads);
1823
1824 _collection_set.initialize(max_regions());
1825
1826 return JNI_OK;
1827 }
1828
1829 void G1CollectedHeap::stop() {
1830 // Stop all concurrent threads. We do this to make sure these threads
1831 // do not continue to execute and access resources (e.g. logging)
1832 // that are destroyed during shutdown.
1833 _cr->stop();
1834 _young_gen_sampling_thread->stop();
1835 _cm_thread->stop();
1836 if (G1StringDedup::is_enabled()) {
1837 G1StringDedup::stop();
1838 }
1839 }
1840
1841 void G1CollectedHeap::safepoint_synchronize_begin() {
1842 SuspendibleThreadSet::synchronize();
1843 }
1844
1845 void G1CollectedHeap::safepoint_synchronize_end() {
1846 SuspendibleThreadSet::desynchronize();
1847 }
1848
1849 void G1CollectedHeap::post_initialize() {
1850 CollectedHeap::post_initialize();
1851 ref_processing_init();
1852 }
1853
1854 void G1CollectedHeap::ref_processing_init() {
1855 // Reference processing in G1 currently works as follows:
1856 //
1857 // * There are two reference processor instances. One is
1858 // used to record and process discovered references
1859 // during concurrent marking; the other is used to
1860 // record and process references during STW pauses
1861 // (both full and incremental).
1862 // * Both ref processors need to 'span' the entire heap as
1863 // the regions in the collection set may be dotted around.
1864 //
1865 // * For the concurrent marking ref processor:
1866 // * Reference discovery is enabled at initial marking.
1867 // * Reference discovery is disabled and the discovered
1868 // references processed etc during remarking.
1869 // * Reference discovery is MT (see below).
1870 // * Reference discovery requires a barrier (see below).
1871 // * Reference processing may or may not be MT
1872 // (depending on the value of ParallelRefProcEnabled
1873 // and ParallelGCThreads).
1874 // * A full GC disables reference discovery by the CM
1875 // ref processor and abandons any entries on it's
1876 // discovered lists.
1877 //
1878 // * For the STW processor:
1879 // * Non MT discovery is enabled at the start of a full GC.
1880 // * Processing and enqueueing during a full GC is non-MT.
1881 // * During a full GC, references are processed after marking.
1882 //
1883 // * Discovery (may or may not be MT) is enabled at the start
1884 // of an incremental evacuation pause.
1885 // * References are processed near the end of a STW evacuation pause.
1886 // * For both types of GC:
1887 // * Discovery is atomic - i.e. not concurrent.
1888 // * Reference discovery will not need a barrier.
1889
1890 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1891
1892 // Concurrent Mark ref processor
1893 _ref_processor_cm =
1894 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1895 mt_processing, // mt processing
1896 ParallelGCThreads, // degree of mt processing
1897 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1898 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1899 false, // Reference discovery is not atomic
1900 &_is_alive_closure_cm, // is alive closure
1901 true); // allow changes to number of processing threads
1902
1903 // STW ref processor
1904 _ref_processor_stw =
1905 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1906 mt_processing, // mt processing
1907 ParallelGCThreads, // degree of mt processing
1908 (ParallelGCThreads > 1), // mt discovery
1909 ParallelGCThreads, // degree of mt discovery
1910 true, // Reference discovery is atomic
1911 &_is_alive_closure_stw, // is alive closure
1912 true); // allow changes to number of processing threads
1913 }
1914
1915 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1916 return &_soft_ref_policy;
1917 }
1918
1919 size_t G1CollectedHeap::capacity() const {
1920 return _hrm->length() * HeapRegion::GrainBytes;
1921 }
1922
1923 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1924 return _hrm->total_free_bytes();
1925 }
1926
1927 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1928 _hot_card_cache->drain(cl, worker_id);
1929 }
1930
1931 // Computes the sum of the storage used by the various regions.
1932 size_t G1CollectedHeap::used() const {
1933 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1934 if (_archive_allocator != NULL) {
1935 result += _archive_allocator->used();
1936 }
1937 return result;
1938 }
1939
1940 size_t G1CollectedHeap::used_unlocked() const {
1941 return _summary_bytes_used;
1942 }
1943
1944 class SumUsedClosure: public HeapRegionClosure {
1945 size_t _used;
1946 public:
1947 SumUsedClosure() : _used(0) {}
1948 bool do_heap_region(HeapRegion* r) {
1949 _used += r->used();
1950 return false;
1951 }
1952 size_t result() { return _used; }
1953 };
1954
1955 size_t G1CollectedHeap::recalculate_used() const {
1956 SumUsedClosure blk;
1957 heap_region_iterate(&blk);
1958 return blk.result();
1959 }
1960
1961 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1962 switch (cause) {
1963 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1964 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1965 case GCCause::_wb_conc_mark: return true;
1966 default : return false;
1967 }
1968 }
1969
1970 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1971 switch (cause) {
1972 case GCCause::_g1_humongous_allocation: return true;
1973 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1974 case GCCause::_wb_breakpoint: return true;
1975 default: return is_user_requested_concurrent_full_gc(cause);
1976 }
1977 }
1978
1979 bool G1CollectedHeap::should_upgrade_to_full_gc(GCCause::Cause cause) {
1980 if (policy()->force_upgrade_to_full()) {
1981 return true;
1982 } else if (should_do_concurrent_full_gc(_gc_cause)) {
1983 return false;
1984 } else if (has_regions_left_for_allocation()) {
1985 return false;
1986 } else {
1987 return true;
1988 }
1989 }
1990
1991 #ifndef PRODUCT
1992 void G1CollectedHeap::allocate_dummy_regions() {
1993 // Let's fill up most of the region
1994 size_t word_size = HeapRegion::GrainWords - 1024;
1995 // And as a result the region we'll allocate will be humongous.
1996 guarantee(is_humongous(word_size), "sanity");
1997
1998 // _filler_array_max_size is set to humongous object threshold
1999 // but temporarily change it to use CollectedHeap::fill_with_object().
2000 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2001
2002 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2003 // Let's use the existing mechanism for the allocation
2004 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2005 if (dummy_obj != NULL) {
2006 MemRegion mr(dummy_obj, word_size);
2007 CollectedHeap::fill_with_object(mr);
2008 } else {
2009 // If we can't allocate once, we probably cannot allocate
2010 // again. Let's get out of the loop.
2011 break;
2012 }
2013 }
2014 }
2015 #endif // !PRODUCT
2016
2017 void G1CollectedHeap::increment_old_marking_cycles_started() {
2018 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2019 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2020 "Wrong marking cycle count (started: %d, completed: %d)",
2021 _old_marking_cycles_started, _old_marking_cycles_completed);
2022
2023 _old_marking_cycles_started++;
2024 }
2025
2026 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2027 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
2028
2029 // We assume that if concurrent == true, then the caller is a
2030 // concurrent thread that was joined the Suspendible Thread
2031 // Set. If there's ever a cheap way to check this, we should add an
2032 // assert here.
2033
2034 // Given that this method is called at the end of a Full GC or of a
2035 // concurrent cycle, and those can be nested (i.e., a Full GC can
2036 // interrupt a concurrent cycle), the number of full collections
2037 // completed should be either one (in the case where there was no
2038 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2039 // behind the number of full collections started.
2040
2041 // This is the case for the inner caller, i.e. a Full GC.
2042 assert(concurrent ||
2043 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2044 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2045 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2046 "is inconsistent with _old_marking_cycles_completed = %u",
2047 _old_marking_cycles_started, _old_marking_cycles_completed);
2048
2049 // This is the case for the outer caller, i.e. the concurrent cycle.
2050 assert(!concurrent ||
2051 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2052 "for outer caller (concurrent cycle): "
2053 "_old_marking_cycles_started = %u "
2054 "is inconsistent with _old_marking_cycles_completed = %u",
2055 _old_marking_cycles_started, _old_marking_cycles_completed);
2056
2057 _old_marking_cycles_completed += 1;
2058
2059 // We need to clear the "in_progress" flag in the CM thread before
2060 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2061 // is set) so that if a waiter requests another System.gc() it doesn't
2062 // incorrectly see that a marking cycle is still in progress.
2063 if (concurrent) {
2064 _cm_thread->set_idle();
2065 }
2066
2067 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2068 // for a full GC to finish that their wait is over.
2069 ml.notify_all();
2070 }
2071
2072 void G1CollectedHeap::collect(GCCause::Cause cause) {
2073 try_collect(cause);
2074 }
2075
2076 // Return true if (x < y) with allowance for wraparound.
2077 static bool gc_counter_less_than(uint x, uint y) {
2078 return (x - y) > (UINT_MAX/2);
2079 }
2080
2081 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2082 // Macro so msg printing is format-checked.
2083 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2084 do { \
2085 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2086 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2087 ResourceMark rm; /* For thread name. */ \
2088 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2089 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2090 Thread::current()->name(), \
2091 GCCause::to_string(cause)); \
2092 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2093 } \
2094 } while (0)
2095
2096 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2097 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2098
2099 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2100 uint gc_counter,
2101 uint old_marking_started_before) {
2102 assert_heap_not_locked();
2103 assert(should_do_concurrent_full_gc(cause),
2104 "Non-concurrent cause %s", GCCause::to_string(cause));
2105
2106 for (uint i = 1; true; ++i) {
2107 // Try to schedule an initial-mark evacuation pause that will
2108 // start a concurrent cycle.
2109 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2110 VM_G1TryInitiateConcMark op(gc_counter,
2111 cause,
2112 policy()->max_pause_time_ms());
2113 VMThread::execute(&op);
2114
2115 // Request is trivially finished.
2116 if (cause == GCCause::_g1_periodic_collection) {
2117 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2118 return op.gc_succeeded();
2119 }
2120
2121 // If VMOp skipped initiating concurrent marking cycle because
2122 // we're terminating, then we're done.
2123 if (op.terminating()) {
2124 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2125 return false;
2126 }
2127
2128 // Lock to get consistent set of values.
2129 uint old_marking_started_after;
2130 uint old_marking_completed_after;
2131 {
2132 MutexLocker ml(Heap_lock);
2133 // Update gc_counter for retrying VMOp if needed. Captured here to be
2134 // consistent with the values we use below for termination tests. If
2135 // a retry is needed after a possible wait, and another collection
2136 // occurs in the meantime, it will cause our retry to be skipped and
2137 // we'll recheck for termination with updated conditions from that
2138 // more recent collection. That's what we want, rather than having
2139 // our retry possibly perform an unnecessary collection.
2140 gc_counter = total_collections();
2141 old_marking_started_after = _old_marking_cycles_started;
2142 old_marking_completed_after = _old_marking_cycles_completed;
2143 }
2144
2145 if (cause == GCCause::_wb_breakpoint) {
2146 if (op.gc_succeeded()) {
2147 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2148 return true;
2149 }
2150 // When _wb_breakpoint there can't be another cycle or deferred.
2151 assert(!op.cycle_already_in_progress(), "invariant");
2152 assert(!op.whitebox_attached(), "invariant");
2153 // Concurrent cycle attempt might have been cancelled by some other
2154 // collection, so retry. Unlike other cases below, we want to retry
2155 // even if cancelled by a STW full collection, because we really want
2156 // to start a concurrent cycle.
2157 if (old_marking_started_before != old_marking_started_after) {
2158 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2159 old_marking_started_before = old_marking_started_after;
2160 }
2161 } else if (!GCCause::is_user_requested_gc(cause)) {
2162 // For an "automatic" (not user-requested) collection, we just need to
2163 // ensure that progress is made.
2164 //
2165 // Request is finished if any of
2166 // (1) the VMOp successfully performed a GC,
2167 // (2) a concurrent cycle was already in progress,
2168 // (3) whitebox is controlling concurrent cycles,
2169 // (4) a new cycle was started (by this thread or some other), or
2170 // (5) a Full GC was performed.
2171 // Cases (4) and (5) are detected together by a change to
2172 // _old_marking_cycles_started.
2173 //
2174 // Note that (1) does not imply (4). If we're still in the mixed
2175 // phase of an earlier concurrent collection, the request to make the
2176 // collection an initial-mark won't be honored. If we don't check for
2177 // both conditions we'll spin doing back-to-back collections.
2178 if (op.gc_succeeded() ||
2179 op.cycle_already_in_progress() ||
2180 op.whitebox_attached() ||
2181 (old_marking_started_before != old_marking_started_after)) {
2182 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2183 return true;
2184 }
2185 } else { // User-requested GC.
2186 // For a user-requested collection, we want to ensure that a complete
2187 // full collection has been performed before returning, but without
2188 // waiting for more than needed.
2189
2190 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2191 // new cycle was started. That's good, because it's not clear what we
2192 // should do otherwise. Trying again just does back to back GCs.
2193 // Can't wait for someone else to start a cycle. And returning fails
2194 // to meet the goal of ensuring a full collection was performed.
2195 assert(!op.gc_succeeded() ||
2196 (old_marking_started_before != old_marking_started_after),
2197 "invariant: succeeded %s, started before %u, started after %u",
2198 BOOL_TO_STR(op.gc_succeeded()),
2199 old_marking_started_before, old_marking_started_after);
2200
2201 // Request is finished if a full collection (concurrent or stw)
2202 // was started after this request and has completed, e.g.
2203 // started_before < completed_after.
2204 if (gc_counter_less_than(old_marking_started_before,
2205 old_marking_completed_after)) {
2206 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2207 return true;
2208 }
2209
2210 if (old_marking_started_after != old_marking_completed_after) {
2211 // If there is an in-progress cycle (possibly started by us), then
2212 // wait for that cycle to complete, e.g.
2213 // while completed_now < started_after.
2214 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2215 MonitorLocker ml(G1OldGCCount_lock);
2216 while (gc_counter_less_than(_old_marking_cycles_completed,
2217 old_marking_started_after)) {
2218 ml.wait();
2219 }
2220 // Request is finished if the collection we just waited for was
2221 // started after this request.
2222 if (old_marking_started_before != old_marking_started_after) {
2223 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2224 return true;
2225 }
2226 }
2227
2228 // If VMOp was successful then it started a new cycle that the above
2229 // wait &etc should have recognized as finishing this request. This
2230 // differs from a non-user-request, where gc_succeeded does not imply
2231 // a new cycle was started.
2232 assert(!op.gc_succeeded(), "invariant");
2233
2234 if (op.cycle_already_in_progress()) {
2235 // If VMOp failed because a cycle was already in progress, it
2236 // is now complete. But it didn't finish this user-requested
2237 // GC, so try again.
2238 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2239 continue;
2240 } else if (op.whitebox_attached()) {
2241 // If WhiteBox wants control, wait for notification of a state
2242 // change in the controller, then try again. Don't wait for
2243 // release of control, since collections may complete while in
2244 // control. Note: This won't recognize a STW full collection
2245 // while waiting; we can't wait on multiple monitors.
2246 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2247 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2248 if (ConcurrentGCBreakpoints::is_controlled()) {
2249 ml.wait();
2250 }
2251 continue;
2252 }
2253 }
2254
2255 // Collection failed and should be retried.
2256 assert(op.transient_failure(), "invariant");
2257
2258 if (GCLocker::is_active_and_needs_gc()) {
2259 // If GCLocker is active, wait until clear before retrying.
2260 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2261 GCLocker::stall_until_clear();
2262 }
2263
2264 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2265 }
2266 }
2267
2268 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2269 assert_heap_not_locked();
2270
2271 // Lock to get consistent set of values.
2272 uint gc_count_before;
2273 uint full_gc_count_before;
2274 uint old_marking_started_before;
2275 {
2276 MutexLocker ml(Heap_lock);
2277 gc_count_before = total_collections();
2278 full_gc_count_before = total_full_collections();
2279 old_marking_started_before = _old_marking_cycles_started;
2280 }
2281
2282 if (should_do_concurrent_full_gc(cause)) {
2283 return try_collect_concurrently(cause,
2284 gc_count_before,
2285 old_marking_started_before);
2286 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2287 // Indicate failure to be consistent with VMOp failure due to
2288 // another collection slipping in after our gc_count but before
2289 // our request is processed.
2290 return false;
2291 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2292 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2293
2294 // Schedule a standard evacuation pause. We're setting word_size
2295 // to 0 which means that we are not requesting a post-GC allocation.
2296 VM_G1CollectForAllocation op(0, /* word_size */
2297 gc_count_before,
2298 cause,
2299 policy()->max_pause_time_ms());
2300 VMThread::execute(&op);
2301 return op.gc_succeeded();
2302 } else {
2303 // Schedule a Full GC.
2304 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2305 VMThread::execute(&op);
2306 return op.gc_succeeded();
2307 }
2308 }
2309
2310 bool G1CollectedHeap::is_in(const void* p) const {
2311 if (_hrm->reserved().contains(p)) {
2312 // Given that we know that p is in the reserved space,
2313 // heap_region_containing() should successfully
2314 // return the containing region.
2315 HeapRegion* hr = heap_region_containing(p);
2316 return hr->is_in(p);
2317 } else {
2318 return false;
2319 }
2320 }
2321
2322 #ifdef ASSERT
2323 bool G1CollectedHeap::is_in_exact(const void* p) const {
2324 bool contains = reserved_region().contains(p);
2325 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2326 if (contains && available) {
2327 return true;
2328 } else {
2329 return false;
2330 }
2331 }
2332 #endif
2333
2334 // Iteration functions.
2335
2336 // Iterates an ObjectClosure over all objects within a HeapRegion.
2337
2338 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2339 ObjectClosure* _cl;
2340 public:
2341 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2342 bool do_heap_region(HeapRegion* r) {
2343 if (!r->is_continues_humongous()) {
2344 r->object_iterate(_cl);
2345 }
2346 return false;
2347 }
2348 };
2349
2350 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2351 IterateObjectClosureRegionClosure blk(cl);
2352 heap_region_iterate(&blk);
2353 }
2354
2355 void G1CollectedHeap::keep_alive(oop obj) {
2356 G1BarrierSet::enqueue(obj);
2357 }
2358
2359 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2360 _hrm->iterate(cl);
2361 }
2362
2363 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2364 HeapRegionClaimer *hrclaimer,
2365 uint worker_id) const {
2366 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2367 }
2368
2369 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2370 HeapRegionClaimer *hrclaimer) const {
2371 _hrm->par_iterate(cl, hrclaimer, 0);
2372 }
2373
2374 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2375 _collection_set.iterate(cl);
2376 }
2377
2378 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2379 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2380 }
2381
2382 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2383 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2384 }
2385
2386 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2387 HeapRegion* hr = heap_region_containing(addr);
2388 return hr->block_start(addr);
2389 }
2390
2391 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2392 HeapRegion* hr = heap_region_containing(addr);
2393 return hr->block_is_obj(addr);
2394 }
2395
2396 bool G1CollectedHeap::supports_tlab_allocation() const {
2397 return true;
2398 }
2399
2400 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2401 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2402 }
2403
2404 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2405 return _eden.length() * HeapRegion::GrainBytes;
2406 }
2407
2408 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2409 // must be equal to the humongous object limit.
2410 size_t G1CollectedHeap::max_tlab_size() const {
2411 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2412 }
2413
2414 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2415 return _allocator->unsafe_max_tlab_alloc();
2416 }
2417
2418 size_t G1CollectedHeap::max_capacity() const {
2419 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2420 }
2421
2422 size_t G1CollectedHeap::max_reserved_capacity() const {
2423 return _hrm->max_length() * HeapRegion::GrainBytes;
2424 }
2425
2426 jlong G1CollectedHeap::millis_since_last_gc() {
2427 // See the notes in GenCollectedHeap::millis_since_last_gc()
2428 // for more information about the implementation.
2429 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2430 _policy->collection_pause_end_millis();
2431 if (ret_val < 0) {
2432 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2433 ". returning zero instead.", ret_val);
2434 return 0;
2435 }
2436 return ret_val;
2437 }
2438
2439 void G1CollectedHeap::deduplicate_string(oop str) {
2440 assert(java_lang_String::is_instance(str), "invariant");
2441
2442 if (G1StringDedup::is_enabled()) {
2443 G1StringDedup::deduplicate(str);
2444 }
2445 }
2446
2447 void G1CollectedHeap::prepare_for_verify() {
2448 _verifier->prepare_for_verify();
2449 }
2450
2451 void G1CollectedHeap::verify(VerifyOption vo) {
2452 _verifier->verify(vo);
2453 }
2454
2455 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2456 return true;
2457 }
2458
2459 bool G1CollectedHeap::is_heterogeneous_heap() const {
2460 return G1Arguments::is_heterogeneous_heap();
2461 }
2462
2463 class PrintRegionClosure: public HeapRegionClosure {
2464 outputStream* _st;
2465 public:
2466 PrintRegionClosure(outputStream* st) : _st(st) {}
2467 bool do_heap_region(HeapRegion* r) {
2468 r->print_on(_st);
2469 return false;
2470 }
2471 };
2472
2473 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2474 const HeapRegion* hr,
2475 const VerifyOption vo) const {
2476 switch (vo) {
2477 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2478 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2479 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2480 default: ShouldNotReachHere();
2481 }
2482 return false; // keep some compilers happy
2483 }
2484
2485 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2486 const VerifyOption vo) const {
2487 switch (vo) {
2488 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2489 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2490 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2491 default: ShouldNotReachHere();
2492 }
2493 return false; // keep some compilers happy
2494 }
2495
2496 void G1CollectedHeap::print_heap_regions() const {
2497 LogTarget(Trace, gc, heap, region) lt;
2498 if (lt.is_enabled()) {
2499 LogStream ls(lt);
2500 print_regions_on(&ls);
2501 }
2502 }
2503
2504 void G1CollectedHeap::print_on(outputStream* st) const {
2505 st->print(" %-20s", "garbage-first heap");
2506 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2507 capacity()/K, used_unlocked()/K);
2508 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2509 p2i(_hrm->reserved().start()),
2510 p2i(_hrm->reserved().end()));
2511 st->cr();
2512 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2513 uint young_regions = young_regions_count();
2514 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2515 (size_t) young_regions * HeapRegion::GrainBytes / K);
2516 uint survivor_regions = survivor_regions_count();
2517 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2518 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2519 st->cr();
2520 if (_numa->is_enabled()) {
2521 uint num_nodes = _numa->num_active_nodes();
2522 st->print(" remaining free region(s) on each NUMA node: ");
2523 const int* node_ids = _numa->node_ids();
2524 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2525 st->print("%d=%u ", node_ids[node_index], _hrm->num_free_regions(node_index));
2526 }
2527 st->cr();
2528 }
2529 MetaspaceUtils::print_on(st);
2530 }
2531
2532 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2533 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2534 "HS=humongous(starts), HC=humongous(continues), "
2535 "CS=collection set, F=free, "
2536 "OA=open archive, CA=closed archive, "
2537 "TAMS=top-at-mark-start (previous, next)");
2538 PrintRegionClosure blk(st);
2539 heap_region_iterate(&blk);
2540 }
2541
2542 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2543 print_on(st);
2544
2545 // Print the per-region information.
2546 print_regions_on(st);
2547 }
2548
2549 void G1CollectedHeap::print_on_error(outputStream* st) const {
2550 this->CollectedHeap::print_on_error(st);
2551
2552 if (_cm != NULL) {
2553 st->cr();
2554 _cm->print_on_error(st);
2555 }
2556 }
2557
2558 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2559 workers()->print_worker_threads_on(st);
2560 _cm_thread->print_on(st);
2561 st->cr();
2562 _cm->print_worker_threads_on(st);
2563 _cr->print_threads_on(st);
2564 _young_gen_sampling_thread->print_on(st);
2565 if (G1StringDedup::is_enabled()) {
2566 G1StringDedup::print_worker_threads_on(st);
2567 }
2568 }
2569
2570 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2571 workers()->threads_do(tc);
2572 tc->do_thread(_cm_thread);
2573 _cm->threads_do(tc);
2574 _cr->threads_do(tc);
2575 tc->do_thread(_young_gen_sampling_thread);
2576 if (G1StringDedup::is_enabled()) {
2577 G1StringDedup::threads_do(tc);
2578 }
2579 }
2580
2581 void G1CollectedHeap::print_tracing_info() const {
2582 rem_set()->print_summary_info();
2583 concurrent_mark()->print_summary_info();
2584 }
2585
2586 #ifndef PRODUCT
2587 // Helpful for debugging RSet issues.
2588
2589 class PrintRSetsClosure : public HeapRegionClosure {
2590 private:
2591 const char* _msg;
2592 size_t _occupied_sum;
2593
2594 public:
2595 bool do_heap_region(HeapRegion* r) {
2596 HeapRegionRemSet* hrrs = r->rem_set();
2597 size_t occupied = hrrs->occupied();
2598 _occupied_sum += occupied;
2599
2600 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2601 if (occupied == 0) {
2602 tty->print_cr(" RSet is empty");
2603 } else {
2604 hrrs->print();
2605 }
2606 tty->print_cr("----------");
2607 return false;
2608 }
2609
2610 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2611 tty->cr();
2612 tty->print_cr("========================================");
2613 tty->print_cr("%s", msg);
2614 tty->cr();
2615 }
2616
2617 ~PrintRSetsClosure() {
2618 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2619 tty->print_cr("========================================");
2620 tty->cr();
2621 }
2622 };
2623
2624 void G1CollectedHeap::print_cset_rsets() {
2625 PrintRSetsClosure cl("Printing CSet RSets");
2626 collection_set_iterate_all(&cl);
2627 }
2628
2629 void G1CollectedHeap::print_all_rsets() {
2630 PrintRSetsClosure cl("Printing All RSets");;
2631 heap_region_iterate(&cl);
2632 }
2633 #endif // PRODUCT
2634
2635 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2636 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2637 }
2638
2639 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2640
2641 size_t eden_used_bytes = _eden.used_bytes();
2642 size_t survivor_used_bytes = _survivor.used_bytes();
2643 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2644
2645 size_t eden_capacity_bytes =
2646 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2647
2648 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2649 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2650 eden_capacity_bytes, survivor_used_bytes, num_regions());
2651 }
2652
2653 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2654 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2655 stats->unused(), stats->used(), stats->region_end_waste(),
2656 stats->regions_filled(), stats->direct_allocated(),
2657 stats->failure_used(), stats->failure_waste());
2658 }
2659
2660 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2661 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2662 gc_tracer->report_gc_heap_summary(when, heap_summary);
2663
2664 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2665 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2666 }
2667
2668 G1CollectedHeap* G1CollectedHeap::heap() {
2669 CollectedHeap* heap = Universe::heap();
2670 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2671 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2672 return (G1CollectedHeap*)heap;
2673 }
2674
2675 void G1CollectedHeap::gc_prologue(bool full) {
2676 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2677
2678 // This summary needs to be printed before incrementing total collections.
2679 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2680
2681 // Update common counters.
2682 increment_total_collections(full /* full gc */);
2683 if (full || collector_state()->in_initial_mark_gc()) {
2684 increment_old_marking_cycles_started();
2685 }
2686
2687 // Fill TLAB's and such
2688 {
2689 Ticks start = Ticks::now();
2690 ensure_parsability(true);
2691 Tickspan dt = Ticks::now() - start;
2692 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2693 }
2694
2695 if (!full) {
2696 // Flush dirty card queues to qset, so later phases don't need to account
2697 // for partially filled per-thread queues and such. Not needed for full
2698 // collections, which ignore those logs.
2699 Ticks start = Ticks::now();
2700 G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2701 Tickspan dt = Ticks::now() - start;
2702 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2703 }
2704 }
2705
2706 void G1CollectedHeap::gc_epilogue(bool full) {
2707 // Update common counters.
2708 if (full) {
2709 // Update the number of full collections that have been completed.
2710 increment_old_marking_cycles_completed(false /* concurrent */);
2711 }
2712
2713 // We are at the end of the GC. Total collections has already been increased.
2714 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2715
2716 // FIXME: what is this about?
2717 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2718 // is set.
2719 #if COMPILER2_OR_JVMCI
2720 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2721 #endif
2722
2723 double start = os::elapsedTime();
2724 resize_all_tlabs();
2725 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2726
2727 MemoryService::track_memory_usage();
2728 // We have just completed a GC. Update the soft reference
2729 // policy with the new heap occupancy
2730 Universe::update_heap_info_at_gc();
2731
2732 // Print NUMA statistics.
2733 _numa->print_statistics();
2734 }
2735
2736 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2737 LogTarget(Trace, gc, heap, verify) lt;
2738
2739 if (lt.is_enabled()) {
2740 LogStream ls(lt);
2741 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2742 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2743 heap_region_iterate(&cl);
2744 }
2745 }
2746
2747 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2748 uint gc_count_before,
2749 bool* succeeded,
2750 GCCause::Cause gc_cause) {
2751 assert_heap_not_locked_and_not_at_safepoint();
2752 VM_G1CollectForAllocation op(word_size,
2753 gc_count_before,
2754 gc_cause,
2755 policy()->max_pause_time_ms());
2756 VMThread::execute(&op);
2757
2758 HeapWord* result = op.result();
2759 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2760 assert(result == NULL || ret_succeeded,
2761 "the result should be NULL if the VM did not succeed");
2762 *succeeded = ret_succeeded;
2763
2764 assert_heap_not_locked();
2765 return result;
2766 }
2767
2768 void G1CollectedHeap::do_concurrent_mark() {
2769 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2770 if (!_cm_thread->in_progress()) {
2771 _cm_thread->set_started();
2772 CGC_lock->notify();
2773 }
2774 }
2775
2776 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2777 // We don't nominate objects with many remembered set entries, on
2778 // the assumption that such objects are likely still live.
2779 HeapRegionRemSet* rem_set = r->rem_set();
2780
2781 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2782 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2783 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2784 }
2785
2786 #ifndef PRODUCT
2787 void G1CollectedHeap::verify_region_attr_remset_update() {
2788 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2789 public:
2790 virtual bool do_heap_region(HeapRegion* r) {
2791 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2792 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2793 assert(r->rem_set()->is_tracked() == needs_remset_update,
2794 "Region %u remset tracking status (%s) different to region attribute (%s)",
2795 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2796 return false;
2797 }
2798 } cl;
2799 heap_region_iterate(&cl);
2800 }
2801 #endif
2802
2803 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2804 public:
2805 bool do_heap_region(HeapRegion* hr) {
2806 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2807 hr->verify_rem_set();
2808 }
2809 return false;
2810 }
2811 };
2812
2813 uint G1CollectedHeap::num_task_queues() const {
2814 return _task_queues->size();
2815 }
2816
2817 #if TASKQUEUE_STATS
2818 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2819 st->print_raw_cr("GC Task Stats");
2820 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2821 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2822 }
2823
2824 void G1CollectedHeap::print_taskqueue_stats() const {
2825 if (!log_is_enabled(Trace, gc, task, stats)) {
2826 return;
2827 }
2828 Log(gc, task, stats) log;
2829 ResourceMark rm;
2830 LogStream ls(log.trace());
2831 outputStream* st = &ls;
2832
2833 print_taskqueue_stats_hdr(st);
2834
2835 TaskQueueStats totals;
2836 const uint n = num_task_queues();
2837 for (uint i = 0; i < n; ++i) {
2838 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2839 totals += task_queue(i)->stats;
2840 }
2841 st->print_raw("tot "); totals.print(st); st->cr();
2842
2843 DEBUG_ONLY(totals.verify());
2844 }
2845
2846 void G1CollectedHeap::reset_taskqueue_stats() {
2847 const uint n = num_task_queues();
2848 for (uint i = 0; i < n; ++i) {
2849 task_queue(i)->stats.reset();
2850 }
2851 }
2852 #endif // TASKQUEUE_STATS
2853
2854 void G1CollectedHeap::wait_for_root_region_scanning() {
2855 double scan_wait_start = os::elapsedTime();
2856 // We have to wait until the CM threads finish scanning the
2857 // root regions as it's the only way to ensure that all the
2858 // objects on them have been correctly scanned before we start
2859 // moving them during the GC.
2860 bool waited = _cm->root_regions()->wait_until_scan_finished();
2861 double wait_time_ms = 0.0;
2862 if (waited) {
2863 double scan_wait_end = os::elapsedTime();
2864 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2865 }
2866 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2867 }
2868
2869 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2870 private:
2871 G1HRPrinter* _hr_printer;
2872 public:
2873 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2874
2875 virtual bool do_heap_region(HeapRegion* r) {
2876 _hr_printer->cset(r);
2877 return false;
2878 }
2879 };
2880
2881 void G1CollectedHeap::start_new_collection_set() {
2882 double start = os::elapsedTime();
2883
2884 collection_set()->start_incremental_building();
2885
2886 clear_region_attr();
2887
2888 guarantee(_eden.length() == 0, "eden should have been cleared");
2889 policy()->transfer_survivors_to_cset(survivor());
2890
2891 // We redo the verification but now wrt to the new CSet which
2892 // has just got initialized after the previous CSet was freed.
2893 _cm->verify_no_collection_set_oops();
2894
2895 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2896 }
2897
2898 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2899
2900 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2901 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2902 collection_set()->optional_region_length());
2903
2904 _cm->verify_no_collection_set_oops();
2905
2906 if (_hr_printer.is_active()) {
2907 G1PrintCollectionSetClosure cl(&_hr_printer);
2908 _collection_set.iterate(&cl);
2909 _collection_set.iterate_optional(&cl);
2910 }
2911 }
2912
2913 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2914 if (collector_state()->in_initial_mark_gc()) {
2915 return G1HeapVerifier::G1VerifyConcurrentStart;
2916 } else if (collector_state()->in_young_only_phase()) {
2917 return G1HeapVerifier::G1VerifyYoungNormal;
2918 } else {
2919 return G1HeapVerifier::G1VerifyMixed;
2920 }
2921 }
2922
2923 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2924 if (VerifyRememberedSets) {
2925 log_info(gc, verify)("[Verifying RemSets before GC]");
2926 VerifyRegionRemSetClosure v_cl;
2927 heap_region_iterate(&v_cl);
2928 }
2929 _verifier->verify_before_gc(type);
2930 _verifier->check_bitmaps("GC Start");
2931 verify_numa_regions("GC Start");
2932 }
2933
2934 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2935 if (VerifyRememberedSets) {
2936 log_info(gc, verify)("[Verifying RemSets after GC]");
2937 VerifyRegionRemSetClosure v_cl;
2938 heap_region_iterate(&v_cl);
2939 }
2940 _verifier->verify_after_gc(type);
2941 _verifier->check_bitmaps("GC End");
2942 verify_numa_regions("GC End");
2943 }
2944
2945 void G1CollectedHeap::expand_heap_after_young_collection(){
2946 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
2947 if (expand_bytes > 0) {
2948 // No need for an ergo logging here,
2949 // expansion_amount() does this when it returns a value > 0.
2950 double expand_ms;
2951 if (!expand(expand_bytes, _workers, &expand_ms)) {
2952 // We failed to expand the heap. Cannot do anything about it.
2953 }
2954 phase_times()->record_expand_heap_time(expand_ms);
2955 }
2956 }
2957
2958 const char* G1CollectedHeap::young_gc_name() const {
2959 if (collector_state()->in_initial_mark_gc()) {
2960 return "Pause Young (Concurrent Start)";
2961 } else if (collector_state()->in_young_only_phase()) {
2962 if (collector_state()->in_young_gc_before_mixed()) {
2963 return "Pause Young (Prepare Mixed)";
2964 } else {
2965 return "Pause Young (Normal)";
2966 }
2967 } else {
2968 return "Pause Young (Mixed)";
2969 }
2970 }
2971
2972 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2973 assert_at_safepoint_on_vm_thread();
2974 guarantee(!is_gc_active(), "collection is not reentrant");
2975
2976 if (GCLocker::check_active_before_gc()) {
2977 return false;
2978 }
2979
2980 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2981 if (should_upgrade_to_full_gc(gc_cause())) {
2982 log_info(gc, ergo)("Attempting maximally compacting collection");
2983 bool result = do_full_collection(false /* explicit gc */,
2984 true /* clear_all_soft_refs */);
2985 // do_full_collection only fails if blocked by GC locker, but
2986 // we've already checked for that above.
2987 assert(result, "invariant");
2988 }
2989 return true;
2990 }
2991
2992 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2993 GCIdMark gc_id_mark;
2994
2995 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2996 ResourceMark rm;
2997
2998 policy()->note_gc_start();
2999
3000 _gc_timer_stw->register_gc_start();
3001 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
3002
3003 wait_for_root_region_scanning();
3004
3005 print_heap_before_gc();
3006 print_heap_regions();
3007 trace_heap_before_gc(_gc_tracer_stw);
3008
3009 _verifier->verify_region_sets_optional();
3010 _verifier->verify_dirty_young_regions();
3011
3012 // We should not be doing initial mark unless the conc mark thread is running
3013 if (!_cm_thread->should_terminate()) {
3014 // This call will decide whether this pause is an initial-mark
3015 // pause. If it is, in_initial_mark_gc() will return true
3016 // for the duration of this pause.
3017 policy()->decide_on_conc_mark_initiation();
3018 }
3019
3020 // We do not allow initial-mark to be piggy-backed on a mixed GC.
3021 assert(!collector_state()->in_initial_mark_gc() ||
3022 collector_state()->in_young_only_phase(), "sanity");
3023 // We also do not allow mixed GCs during marking.
3024 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
3025
3026 // Record whether this pause is an initial mark. When the current
3027 // thread has completed its logging output and it's safe to signal
3028 // the CM thread, the flag's value in the policy has been reset.
3029 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
3030 if (should_start_conc_mark) {
3031 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
3032 }
3033
3034 // Inner scope for scope based logging, timers, and stats collection
3035 {
3036 G1EvacuationInfo evacuation_info;
3037
3038 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
3039
3040 GCTraceCPUTime tcpu;
3041
3042 GCTraceTime(Info, gc) tm(young_gc_name(), NULL, gc_cause(), true);
3043
3044 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
3045 workers()->active_workers(),
3046 Threads::number_of_non_daemon_threads());
3047 active_workers = workers()->update_active_workers(active_workers);
3048 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
3049
3050 G1MonitoringScope ms(g1mm(),
3051 false /* full_gc */,
3052 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
3053
3054 G1HeapTransition heap_transition(this);
3055
3056 {
3057 IsGCActiveMark x;
3058
3059 gc_prologue(false);
3060
3061 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
3062 verify_before_young_collection(verify_type);
3063
3064 {
3065 // The elapsed time induced by the start time below deliberately elides
3066 // the possible verification above.
3067 double sample_start_time_sec = os::elapsedTime();
3068
3069 // Please see comment in g1CollectedHeap.hpp and
3070 // G1CollectedHeap::ref_processing_init() to see how
3071 // reference processing currently works in G1.
3072 _ref_processor_stw->enable_discovery();
3073
3074 // We want to temporarily turn off discovery by the
3075 // CM ref processor, if necessary, and turn it back on
3076 // on again later if we do. Using a scoped
3077 // NoRefDiscovery object will do this.
3078 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
3079
3080 policy()->record_collection_pause_start(sample_start_time_sec);
3081
3082 // Forget the current allocation region (we might even choose it to be part
3083 // of the collection set!).
3084 _allocator->release_mutator_alloc_regions();
3085
3086 calculate_collection_set(evacuation_info, target_pause_time_ms);
3087
3088 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3089 G1ParScanThreadStateSet per_thread_states(this,
3090 &rdcqs,
3091 workers()->active_workers(),
3092 collection_set()->young_region_length(),
3093 collection_set()->optional_region_length());
3094 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3095
3096 // Actually do the work...
3097 evacuate_initial_collection_set(&per_thread_states);
3098
3099 if (_collection_set.optional_region_length() != 0) {
3100 evacuate_optional_collection_set(&per_thread_states);
3101 }
3102 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3103
3104 start_new_collection_set();
3105
3106 _survivor_evac_stats.adjust_desired_plab_sz();
3107 _old_evac_stats.adjust_desired_plab_sz();
3108
3109 if (should_start_conc_mark) {
3110 // We have to do this before we notify the CM threads that
3111 // they can start working to make sure that all the
3112 // appropriate initialization is done on the CM object.
3113 concurrent_mark()->post_initial_mark();
3114 // Note that we don't actually trigger the CM thread at
3115 // this point. We do that later when we're sure that
3116 // the current thread has completed its logging output.
3117 }
3118
3119 allocate_dummy_regions();
3120
3121 _allocator->init_mutator_alloc_regions();
3122
3123 expand_heap_after_young_collection();
3124
3125 double sample_end_time_sec = os::elapsedTime();
3126 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3127 policy()->record_collection_pause_end(pause_time_ms);
3128 }
3129
3130 verify_after_young_collection(verify_type);
3131
3132 gc_epilogue(false);
3133 }
3134
3135 // Print the remainder of the GC log output.
3136 if (evacuation_failed()) {
3137 log_info(gc)("To-space exhausted");
3138 }
3139
3140 policy()->print_phases();
3141 heap_transition.print();
3142
3143 _hrm->verify_optional();
3144 _verifier->verify_region_sets_optional();
3145
3146 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3147 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3148
3149 print_heap_after_gc();
3150 print_heap_regions();
3151 trace_heap_after_gc(_gc_tracer_stw);
3152
3153 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3154 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3155 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3156 // before any GC notifications are raised.
3157 g1mm()->update_sizes();
3158
3159 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3160 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
3161 _gc_timer_stw->register_gc_end();
3162 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3163 }
3164 // It should now be safe to tell the concurrent mark thread to start
3165 // without its logging output interfering with the logging output
3166 // that came from the pause.
3167
3168 if (should_start_conc_mark) {
3169 // CAUTION: after the doConcurrentMark() call below, the concurrent marking
3170 // thread(s) could be running concurrently with us. Make sure that anything
3171 // after this point does not assume that we are the only GC thread running.
3172 // Note: of course, the actual marking work will not start until the safepoint
3173 // itself is released in SuspendibleThreadSet::desynchronize().
3174 do_concurrent_mark();
3175 ConcurrentGCBreakpoints::notify_idle_to_active();
3176 }
3177 }
3178
3179 void G1CollectedHeap::remove_self_forwarding_pointers(G1RedirtyCardsQueueSet* rdcqs) {
3180 G1ParRemoveSelfForwardPtrsTask rsfp_task(rdcqs);
3181 workers()->run_task(&rsfp_task);
3182 }
3183
3184 void G1CollectedHeap::restore_after_evac_failure(G1RedirtyCardsQueueSet* rdcqs) {
3185 double remove_self_forwards_start = os::elapsedTime();
3186
3187 remove_self_forwarding_pointers(rdcqs);
3188 _preserved_marks_set.restore(workers());
3189
3190 phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3191 }
3192
3193 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3194 if (!_evacuation_failed) {
3195 _evacuation_failed = true;
3196 }
3197
3198 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3199 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3200 }
3201
3202 bool G1ParEvacuateFollowersClosure::offer_termination() {
3203 EventGCPhaseParallel event;
3204 G1ParScanThreadState* const pss = par_scan_state();
3205 start_term_time();
3206 const bool res = terminator()->offer_termination();
3207 end_term_time();
3208 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3209 return res;
3210 }
3211
3212 void G1ParEvacuateFollowersClosure::do_void() {
3213 EventGCPhaseParallel event;
3214 G1ParScanThreadState* const pss = par_scan_state();
3215 pss->trim_queue();
3216 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3217 do {
3218 EventGCPhaseParallel event;
3219 pss->steal_and_trim_queue(queues());
3220 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3221 } while (!offer_termination());
3222 }
3223
3224 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3225 bool class_unloading_occurred) {
3226 uint num_workers = workers()->active_workers();
3227 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred, false);
3228 workers()->run_task(&unlink_task);
3229 }
3230
3231 // Clean string dedup data structures.
3232 // Ideally we would prefer to use a StringDedupCleaningTask here, but we want to
3233 // record the durations of the phases. Hence the almost-copy.
3234 class G1StringDedupCleaningTask : public AbstractGangTask {
3235 BoolObjectClosure* _is_alive;
3236 OopClosure* _keep_alive;
3237 G1GCPhaseTimes* _phase_times;
3238
3239 public:
3240 G1StringDedupCleaningTask(BoolObjectClosure* is_alive,
3241 OopClosure* keep_alive,
3242 G1GCPhaseTimes* phase_times) :
3243 AbstractGangTask("Partial Cleaning Task"),
3244 _is_alive(is_alive),
3245 _keep_alive(keep_alive),
3246 _phase_times(phase_times)
3247 {
3248 assert(G1StringDedup::is_enabled(), "String deduplication disabled.");
3249 StringDedup::gc_prologue(true);
3250 }
3251
3252 ~G1StringDedupCleaningTask() {
3253 StringDedup::gc_epilogue();
3254 }
3255
3256 void work(uint worker_id) {
3257 StringDedupUnlinkOrOopsDoClosure cl(_is_alive, _keep_alive);
3258 {
3259 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupQueueFixup, worker_id);
3260 StringDedupQueue::unlink_or_oops_do(&cl);
3261 }
3262 {
3263 G1GCParPhaseTimesTracker x(_phase_times, G1GCPhaseTimes::StringDedupTableFixup, worker_id);
3264 StringDedupTable::unlink_or_oops_do(&cl, worker_id);
3265 }
3266 }
3267 };
3268
3269 void G1CollectedHeap::string_dedup_cleaning(BoolObjectClosure* is_alive,
3270 OopClosure* keep_alive,
3271 G1GCPhaseTimes* phase_times) {
3272 G1StringDedupCleaningTask cl(is_alive, keep_alive, phase_times);
3273 workers()->run_task(&cl);
3274 }
3275
3276 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3277 private:
3278 G1RedirtyCardsQueueSet* _qset;
3279 G1CollectedHeap* _g1h;
3280 BufferNode* volatile _nodes;
3281
3282 void par_apply(RedirtyLoggedCardTableEntryClosure* cl, uint worker_id) {
3283 size_t buffer_size = _qset->buffer_size();
3284 BufferNode* next = Atomic::load(&_nodes);
3285 while (next != NULL) {
3286 BufferNode* node = next;
3287 next = Atomic::cmpxchg(&_nodes, node, node->next());
3288 if (next == node) {
3289 cl->apply_to_buffer(node, buffer_size, worker_id);
3290 next = node->next();
3291 }
3292 }
3293 }
3294
3295 public:
3296 G1RedirtyLoggedCardsTask(G1RedirtyCardsQueueSet* qset, G1CollectedHeap* g1h) :
3297 AbstractGangTask("Redirty Cards"),
3298 _qset(qset), _g1h(g1h), _nodes(qset->all_completed_buffers()) { }
3299
3300 virtual void work(uint worker_id) {
3301 G1GCPhaseTimes* p = _g1h->phase_times();
3302 G1GCParPhaseTimesTracker x(p, G1GCPhaseTimes::RedirtyCards, worker_id);
3303
3304 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3305 par_apply(&cl, worker_id);
3306
3307 p->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3308 }
3309 };
3310
3311 void G1CollectedHeap::redirty_logged_cards(G1RedirtyCardsQueueSet* rdcqs) {
3312 double redirty_logged_cards_start = os::elapsedTime();
3313
3314 G1RedirtyLoggedCardsTask redirty_task(rdcqs, this);
3315 workers()->run_task(&redirty_task);
3316
3317 G1DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3318 dcq.merge_bufferlists(rdcqs);
3319
3320 phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3321 }
3322
3323 // Weak Reference Processing support
3324
3325 bool G1STWIsAliveClosure::do_object_b(oop p) {
3326 // An object is reachable if it is outside the collection set,
3327 // or is inside and copied.
3328 return !_g1h->is_in_cset(p) || p->is_forwarded();
3329 }
3330
3331 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3332 assert(obj != NULL, "must not be NULL");
3333 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3334 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3335 // may falsely indicate that this is not the case here: however the collection set only
3336 // contains old regions when concurrent mark is not running.
3337 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3338 }
3339
3340 // Non Copying Keep Alive closure
3341 class G1KeepAliveClosure: public OopClosure {
3342 G1CollectedHeap*_g1h;
3343 public:
3344 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3345 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3346 void do_oop(oop* p) {
3347 oop obj = *p;
3348 assert(obj != NULL, "the caller should have filtered out NULL values");
3349
3350 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3351 if (!region_attr.is_in_cset_or_humongous()) {
3352 return;
3353 }
3354 if (region_attr.is_in_cset()) {
3355 assert( obj->is_forwarded(), "invariant" );
3356 *p = obj->forwardee();
3357 } else {
3358 assert(!obj->is_forwarded(), "invariant" );
3359 assert(region_attr.is_humongous(),
3360 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3361 _g1h->set_humongous_is_live(obj);
3362 }
3363 }
3364 };
3365
3366 // Copying Keep Alive closure - can be called from both
3367 // serial and parallel code as long as different worker
3368 // threads utilize different G1ParScanThreadState instances
3369 // and different queues.
3370
3371 class G1CopyingKeepAliveClosure: public OopClosure {
3372 G1CollectedHeap* _g1h;
3373 G1ParScanThreadState* _par_scan_state;
3374
3375 public:
3376 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3377 G1ParScanThreadState* pss):
3378 _g1h(g1h),
3379 _par_scan_state(pss)
3380 {}
3381
3382 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3383 virtual void do_oop( oop* p) { do_oop_work(p); }
3384
3385 template <class T> void do_oop_work(T* p) {
3386 oop obj = RawAccess<>::oop_load(p);
3387
3388 if (_g1h->is_in_cset_or_humongous(obj)) {
3389 // If the referent object has been forwarded (either copied
3390 // to a new location or to itself in the event of an
3391 // evacuation failure) then we need to update the reference
3392 // field and, if both reference and referent are in the G1
3393 // heap, update the RSet for the referent.
3394 //
3395 // If the referent has not been forwarded then we have to keep
3396 // it alive by policy. Therefore we have copy the referent.
3397 //
3398 // When the queue is drained (after each phase of reference processing)
3399 // the object and it's followers will be copied, the reference field set
3400 // to point to the new location, and the RSet updated.
3401 _par_scan_state->push_on_queue(ScannerTask(p));
3402 }
3403 }
3404 };
3405
3406 // Serial drain queue closure. Called as the 'complete_gc'
3407 // closure for each discovered list in some of the
3408 // reference processing phases.
3409
3410 class G1STWDrainQueueClosure: public VoidClosure {
3411 protected:
3412 G1CollectedHeap* _g1h;
3413 G1ParScanThreadState* _par_scan_state;
3414
3415 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3416
3417 public:
3418 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3419 _g1h(g1h),
3420 _par_scan_state(pss)
3421 { }
3422
3423 void do_void() {
3424 G1ParScanThreadState* const pss = par_scan_state();
3425 pss->trim_queue();
3426 }
3427 };
3428
3429 // Parallel Reference Processing closures
3430
3431 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3432 // processing during G1 evacuation pauses.
3433
3434 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3435 private:
3436 G1CollectedHeap* _g1h;
3437 G1ParScanThreadStateSet* _pss;
3438 ScannerTasksQueueSet* _queues;
3439 WorkGang* _workers;
3440
3441 public:
3442 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3443 G1ParScanThreadStateSet* per_thread_states,
3444 WorkGang* workers,
3445 ScannerTasksQueueSet *task_queues) :
3446 _g1h(g1h),
3447 _pss(per_thread_states),
3448 _queues(task_queues),
3449 _workers(workers)
3450 {
3451 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3452 }
3453
3454 // Executes the given task using concurrent marking worker threads.
3455 virtual void execute(ProcessTask& task, uint ergo_workers);
3456 };
3457
3458 // Gang task for possibly parallel reference processing
3459
3460 class G1STWRefProcTaskProxy: public AbstractGangTask {
3461 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3462 ProcessTask& _proc_task;
3463 G1CollectedHeap* _g1h;
3464 G1ParScanThreadStateSet* _pss;
3465 ScannerTasksQueueSet* _task_queues;
3466 TaskTerminator* _terminator;
3467
3468 public:
3469 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3470 G1CollectedHeap* g1h,
3471 G1ParScanThreadStateSet* per_thread_states,
3472 ScannerTasksQueueSet *task_queues,
3473 TaskTerminator* terminator) :
3474 AbstractGangTask("Process reference objects in parallel"),
3475 _proc_task(proc_task),
3476 _g1h(g1h),
3477 _pss(per_thread_states),
3478 _task_queues(task_queues),
3479 _terminator(terminator)
3480 {}
3481
3482 virtual void work(uint worker_id) {
3483 // The reference processing task executed by a single worker.
3484 ResourceMark rm;
3485 HandleMark hm;
3486
3487 G1STWIsAliveClosure is_alive(_g1h);
3488
3489 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3490 pss->set_ref_discoverer(NULL);
3491
3492 // Keep alive closure.
3493 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3494
3495 // Complete GC closure
3496 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3497
3498 // Call the reference processing task's work routine.
3499 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3500
3501 // Note we cannot assert that the refs array is empty here as not all
3502 // of the processing tasks (specifically phase2 - pp2_work) execute
3503 // the complete_gc closure (which ordinarily would drain the queue) so
3504 // the queue may not be empty.
3505 }
3506 };
3507
3508 // Driver routine for parallel reference processing.
3509 // Creates an instance of the ref processing gang
3510 // task and has the worker threads execute it.
3511 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3512 assert(_workers != NULL, "Need parallel worker threads.");
3513
3514 assert(_workers->active_workers() >= ergo_workers,
3515 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3516 ergo_workers, _workers->active_workers());
3517 TaskTerminator terminator(ergo_workers, _queues);
3518 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3519
3520 _workers->run_task(&proc_task_proxy, ergo_workers);
3521 }
3522
3523 // End of weak reference support closures
3524
3525 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3526 double ref_proc_start = os::elapsedTime();
3527
3528 ReferenceProcessor* rp = _ref_processor_stw;
3529 assert(rp->discovery_enabled(), "should have been enabled");
3530
3531 // Closure to test whether a referent is alive.
3532 G1STWIsAliveClosure is_alive(this);
3533
3534 // Even when parallel reference processing is enabled, the processing
3535 // of JNI refs is serial and performed serially by the current thread
3536 // rather than by a worker. The following PSS will be used for processing
3537 // JNI refs.
3538
3539 // Use only a single queue for this PSS.
3540 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3541 pss->set_ref_discoverer(NULL);
3542 assert(pss->queue_is_empty(), "pre-condition");
3543
3544 // Keep alive closure.
3545 G1CopyingKeepAliveClosure keep_alive(this, pss);
3546
3547 // Serial Complete GC closure
3548 G1STWDrainQueueClosure drain_queue(this, pss);
3549
3550 // Setup the soft refs policy...
3551 rp->setup_policy(false);
3552
3553 ReferenceProcessorPhaseTimes* pt = phase_times()->ref_phase_times();
3554
3555 ReferenceProcessorStats stats;
3556 if (!rp->processing_is_mt()) {
3557 // Serial reference processing...
3558 stats = rp->process_discovered_references(&is_alive,
3559 &keep_alive,
3560 &drain_queue,
3561 NULL,
3562 pt);
3563 } else {
3564 uint no_of_gc_workers = workers()->active_workers();
3565
3566 // Parallel reference processing
3567 assert(no_of_gc_workers <= rp->max_num_queues(),
3568 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3569 no_of_gc_workers, rp->max_num_queues());
3570
3571 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3572 stats = rp->process_discovered_references(&is_alive,
3573 &keep_alive,
3574 &drain_queue,
3575 &par_task_executor,
3576 pt);
3577 }
3578
3579 _gc_tracer_stw->report_gc_reference_stats(stats);
3580
3581 // We have completed copying any necessary live referent objects.
3582 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3583
3584 make_pending_list_reachable();
3585
3586 assert(!rp->discovery_enabled(), "Postcondition");
3587 rp->verify_no_references_recorded();
3588
3589 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3590 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3591 }
3592
3593 void G1CollectedHeap::make_pending_list_reachable() {
3594 if (collector_state()->in_initial_mark_gc()) {
3595 oop pll_head = Universe::reference_pending_list();
3596 if (pll_head != NULL) {
3597 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3598 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3599 }
3600 }
3601 }
3602
3603 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3604 Ticks start = Ticks::now();
3605 per_thread_states->flush();
3606 phase_times()->record_or_add_time_secs(G1GCPhaseTimes::MergePSS, 0 /* worker_id */, (Ticks::now() - start).seconds());
3607 }
3608
3609 class G1PrepareEvacuationTask : public AbstractGangTask {
3610 class G1PrepareRegionsClosure : public HeapRegionClosure {
3611 G1CollectedHeap* _g1h;
3612 G1PrepareEvacuationTask* _parent_task;
3613 size_t _worker_humongous_total;
3614 size_t _worker_humongous_candidates;
3615
3616 bool humongous_region_is_candidate(HeapRegion* region) const {
3617 assert(region->is_starts_humongous(), "Must start a humongous object");
3618
3619 oop obj = oop(region->bottom());
3620
3621 // Dead objects cannot be eager reclaim candidates. Due to class
3622 // unloading it is unsafe to query their classes so we return early.
3623 if (_g1h->is_obj_dead(obj, region)) {
3624 return false;
3625 }
3626
3627 // If we do not have a complete remembered set for the region, then we can
3628 // not be sure that we have all references to it.
3629 if (!region->rem_set()->is_complete()) {
3630 return false;
3631 }
3632 // Candidate selection must satisfy the following constraints
3633 // while concurrent marking is in progress:
3634 //
3635 // * In order to maintain SATB invariants, an object must not be
3636 // reclaimed if it was allocated before the start of marking and
3637 // has not had its references scanned. Such an object must have
3638 // its references (including type metadata) scanned to ensure no
3639 // live objects are missed by the marking process. Objects
3640 // allocated after the start of concurrent marking don't need to
3641 // be scanned.
3642 //
3643 // * An object must not be reclaimed if it is on the concurrent
3644 // mark stack. Objects allocated after the start of concurrent
3645 // marking are never pushed on the mark stack.
3646 //
3647 // Nominating only objects allocated after the start of concurrent
3648 // marking is sufficient to meet both constraints. This may miss
3649 // some objects that satisfy the constraints, but the marking data
3650 // structures don't support efficiently performing the needed
3651 // additional tests or scrubbing of the mark stack.
3652 //
3653 // However, we presently only nominate is_typeArray() objects.
3654 // A humongous object containing references induces remembered
3655 // set entries on other regions. In order to reclaim such an
3656 // object, those remembered sets would need to be cleaned up.
3657 //
3658 // We also treat is_typeArray() objects specially, allowing them
3659 // to be reclaimed even if allocated before the start of
3660 // concurrent mark. For this we rely on mark stack insertion to
3661 // exclude is_typeArray() objects, preventing reclaiming an object
3662 // that is in the mark stack. We also rely on the metadata for
3663 // such objects to be built-in and so ensured to be kept live.
3664 // Frequent allocation and drop of large binary blobs is an
3665 // important use case for eager reclaim, and this special handling
3666 // may reduce needed headroom.
3667
3668 return obj->is_typeArray() &&
3669 _g1h->is_potential_eager_reclaim_candidate(region);
3670 }
3671
3672 public:
3673 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3674 _g1h(g1h),
3675 _parent_task(parent_task),
3676 _worker_humongous_total(0),
3677 _worker_humongous_candidates(0) { }
3678
3679 ~G1PrepareRegionsClosure() {
3680 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3681 _parent_task->add_humongous_total(_worker_humongous_total);
3682 }
3683
3684 virtual bool do_heap_region(HeapRegion* hr) {
3685 // First prepare the region for scanning
3686 _g1h->rem_set()->prepare_region_for_scan(hr);
3687
3688 // Now check if region is a humongous candidate
3689 if (!hr->is_starts_humongous()) {
3690 _g1h->register_region_with_region_attr(hr);
3691 return false;
3692 }
3693
3694 uint index = hr->hrm_index();
3695 if (humongous_region_is_candidate(hr)) {
3696 _g1h->set_humongous_reclaim_candidate(index, true);
3697 _g1h->register_humongous_region_with_region_attr(index);
3698 _worker_humongous_candidates++;
3699 // We will later handle the remembered sets of these regions.
3700 } else {
3701 _g1h->set_humongous_reclaim_candidate(index, false);
3702 _g1h->register_region_with_region_attr(hr);
3703 }
3704 _worker_humongous_total++;
3705
3706 return false;
3707 }
3708 };
3709
3710 G1CollectedHeap* _g1h;
3711 HeapRegionClaimer _claimer;
3712 volatile size_t _humongous_total;
3713 volatile size_t _humongous_candidates;
3714 public:
3715 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3716 AbstractGangTask("Prepare Evacuation"),
3717 _g1h(g1h),
3718 _claimer(_g1h->workers()->active_workers()),
3719 _humongous_total(0),
3720 _humongous_candidates(0) { }
3721
3722 ~G1PrepareEvacuationTask() {
3723 _g1h->set_has_humongous_reclaim_candidate(_humongous_candidates > 0);
3724 }
3725
3726 void work(uint worker_id) {
3727 G1PrepareRegionsClosure cl(_g1h, this);
3728 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3729 }
3730
3731 void add_humongous_candidates(size_t candidates) {
3732 Atomic::add(&_humongous_candidates, candidates);
3733 }
3734
3735 void add_humongous_total(size_t total) {
3736 Atomic::add(&_humongous_total, total);
3737 }
3738
3739 size_t humongous_candidates() {
3740 return _humongous_candidates;
3741 }
3742
3743 size_t humongous_total() {
3744 return _humongous_total;
3745 }
3746 };
3747
3748 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3749 _bytes_used_during_gc = 0;
3750
3751 _expand_heap_after_alloc_failure = true;
3752 _evacuation_failed = false;
3753
3754 // Disable the hot card cache.
3755 _hot_card_cache->reset_hot_cache_claimed_index();
3756 _hot_card_cache->set_use_cache(false);
3757
3758 // Initialize the GC alloc regions.
3759 _allocator->init_gc_alloc_regions(evacuation_info);
3760
3761 {
3762 Ticks start = Ticks::now();
3763 rem_set()->prepare_for_scan_heap_roots();
3764 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3765 }
3766
3767 {
3768 G1PrepareEvacuationTask g1_prep_task(this);
3769 Tickspan task_time = run_task(&g1_prep_task);
3770
3771 phase_times()->record_register_regions(task_time.seconds() * 1000.0,
3772 g1_prep_task.humongous_total(),
3773 g1_prep_task.humongous_candidates());
3774 }
3775
3776 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3777 _preserved_marks_set.assert_empty();
3778
3779 #if COMPILER2_OR_JVMCI
3780 DerivedPointerTable::clear();
3781 #endif
3782
3783 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3784 if (collector_state()->in_initial_mark_gc()) {
3785 concurrent_mark()->pre_initial_mark();
3786
3787 double start_clear_claimed_marks = os::elapsedTime();
3788
3789 ClassLoaderDataGraph::clear_claimed_marks();
3790
3791 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3792 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3793 }
3794
3795 // Should G1EvacuationFailureALot be in effect for this GC?
3796 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3797 }
3798
3799 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3800 protected:
3801 G1CollectedHeap* _g1h;
3802 G1ParScanThreadStateSet* _per_thread_states;
3803 ScannerTasksQueueSet* _task_queues;
3804 TaskTerminator _terminator;
3805 uint _num_workers;
3806
3807 void evacuate_live_objects(G1ParScanThreadState* pss,
3808 uint worker_id,
3809 G1GCPhaseTimes::GCParPhases objcopy_phase,
3810 G1GCPhaseTimes::GCParPhases termination_phase) {
3811 G1GCPhaseTimes* p = _g1h->phase_times();
3812
3813 Ticks start = Ticks::now();
3814 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3815 cl.do_void();
3816
3817 assert(pss->queue_is_empty(), "should be empty");
3818
3819 Tickspan evac_time = (Ticks::now() - start);
3820 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3821
3822 if (termination_phase == G1GCPhaseTimes::Termination) {
3823 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3824 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3825 } else {
3826 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3827 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3828 }
3829 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming during evacuation");
3830 }
3831
3832 virtual void start_work(uint worker_id) { }
3833
3834 virtual void end_work(uint worker_id) { }
3835
3836 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3837
3838 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3839
3840 public:
3841 G1EvacuateRegionsBaseTask(const char* name,
3842 G1ParScanThreadStateSet* per_thread_states,
3843 ScannerTasksQueueSet* task_queues,
3844 uint num_workers) :
3845 AbstractGangTask(name),
3846 _g1h(G1CollectedHeap::heap()),
3847 _per_thread_states(per_thread_states),
3848 _task_queues(task_queues),
3849 _terminator(num_workers, _task_queues),
3850 _num_workers(num_workers)
3851 { }
3852
3853 void work(uint worker_id) {
3854 start_work(worker_id);
3855
3856 {
3857 ResourceMark rm;
3858 HandleMark hm;
3859
3860 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3861 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3862
3863 scan_roots(pss, worker_id);
3864 evacuate_live_objects(pss, worker_id);
3865 }
3866
3867 end_work(worker_id);
3868 }
3869 };
3870
3871 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3872 G1RootProcessor* _root_processor;
3873
3874 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3875 _root_processor->evacuate_roots(pss, worker_id);
3876 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy);
3877 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3878 }
3879
3880 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3881 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3882 }
3883
3884 void start_work(uint worker_id) {
3885 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3886 }
3887
3888 void end_work(uint worker_id) {
3889 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3890 }
3891
3892 public:
3893 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3894 G1ParScanThreadStateSet* per_thread_states,
3895 ScannerTasksQueueSet* task_queues,
3896 G1RootProcessor* root_processor,
3897 uint num_workers) :
3898 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3899 _root_processor(root_processor)
3900 { }
3901 };
3902
3903 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3904 G1GCPhaseTimes* p = phase_times();
3905
3906 {
3907 Ticks start = Ticks::now();
3908 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3909 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3910 }
3911
3912 Tickspan task_time;
3913 const uint num_workers = workers()->active_workers();
3914
3915 Ticks start_processing = Ticks::now();
3916 {
3917 G1RootProcessor root_processor(this, num_workers);
3918 G1EvacuateRegionsTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, num_workers);
3919 task_time = run_task(&g1_par_task);
3920 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3921 // To extract its code root fixup time we measure total time of this scope and
3922 // subtract from the time the WorkGang task took.
3923 }
3924 Tickspan total_processing = Ticks::now() - start_processing;
3925
3926 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3927 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3928 }
3929
3930 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3931
3932 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3933 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy);
3934 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3935 }
3936
3937 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3938 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3939 }
3940
3941 public:
3942 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3943 ScannerTasksQueueSet* queues,
3944 uint num_workers) :
3945 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3946 }
3947 };
3948
3949 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3950 class G1MarkScope : public MarkScope { };
3951
3952 Tickspan task_time;
3953
3954 Ticks start_processing = Ticks::now();
3955 {
3956 G1MarkScope code_mark_scope;
3957 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3958 task_time = run_task(&task);
3959 // See comment in evacuate_collection_set() for the reason of the scope.
3960 }
3961 Tickspan total_processing = Ticks::now() - start_processing;
3962
3963 G1GCPhaseTimes* p = phase_times();
3964 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3965 }
3966
3967 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3968 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3969
3970 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3971
3972 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3973 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3974
3975 if (time_left_ms < 0 ||
3976 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3977 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3978 _collection_set.optional_region_length(), time_left_ms);
3979 break;
3980 }
3981
3982 {
3983 Ticks start = Ticks::now();
3984 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3985 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3986 }
3987
3988 {
3989 Ticks start = Ticks::now();
3990 evacuate_next_optional_regions(per_thread_states);
3991 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3992 }
3993 }
3994
3995 _collection_set.abandon_optional_collection_set(per_thread_states);
3996 }
3997
3998 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3999 G1RedirtyCardsQueueSet* rdcqs,
4000 G1ParScanThreadStateSet* per_thread_states) {
4001 G1GCPhaseTimes* p = phase_times();
4002
4003 rem_set()->cleanup_after_scan_heap_roots();
4004
4005 // Process any discovered reference objects - we have
4006 // to do this _before_ we retire the GC alloc regions
4007 // as we may have to copy some 'reachable' referent
4008 // objects (and their reachable sub-graphs) that were
4009 // not copied during the pause.
4010 process_discovered_references(per_thread_states);
4011
4012 G1STWIsAliveClosure is_alive(this);
4013 G1KeepAliveClosure keep_alive(this);
4014
4015 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
4016
4017 if (G1StringDedup::is_enabled()) {
4018 double string_dedup_time_ms = os::elapsedTime();
4019
4020 string_dedup_cleaning(&is_alive, &keep_alive, p);
4021
4022 double string_cleanup_time_ms = (os::elapsedTime() - string_dedup_time_ms) * 1000.0;
4023 p->record_string_deduplication_time(string_cleanup_time_ms);
4024 }
4025
4026 _allocator->release_gc_alloc_regions(evacuation_info);
4027
4028 if (evacuation_failed()) {
4029 restore_after_evac_failure(rdcqs);
4030
4031 // Reset the G1EvacuationFailureALot counters and flags
4032 NOT_PRODUCT(reset_evacuation_should_fail();)
4033
4034 double recalculate_used_start = os::elapsedTime();
4035 set_used(recalculate_used());
4036 p->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
4037
4038 if (_archive_allocator != NULL) {
4039 _archive_allocator->clear_used();
4040 }
4041 for (uint i = 0; i < ParallelGCThreads; i++) {
4042 if (_evacuation_failed_info_array[i].has_failed()) {
4043 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4044 }
4045 }
4046 } else {
4047 // The "used" of the the collection set have already been subtracted
4048 // when they were freed. Add in the bytes used.
4049 increase_used(_bytes_used_during_gc);
4050 }
4051
4052 _preserved_marks_set.assert_empty();
4053
4054 merge_per_thread_state_info(per_thread_states);
4055
4056 // Reset and re-enable the hot card cache.
4057 // Note the counts for the cards in the regions in the
4058 // collection set are reset when the collection set is freed.
4059 _hot_card_cache->reset_hot_cache();
4060 _hot_card_cache->set_use_cache(true);
4061
4062 purge_code_root_memory();
4063
4064 redirty_logged_cards(rdcqs);
4065
4066 free_collection_set(&_collection_set, evacuation_info, per_thread_states->surviving_young_words());
4067
4068 eagerly_reclaim_humongous_regions();
4069
4070 record_obj_copy_mem_stats();
4071
4072 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
4073 evacuation_info.set_bytes_used(_bytes_used_during_gc);
4074
4075 #if COMPILER2_OR_JVMCI
4076 double start = os::elapsedTime();
4077 DerivedPointerTable::update_pointers();
4078 phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
4079 #endif
4080 policy()->print_age_table();
4081 }
4082
4083 void G1CollectedHeap::record_obj_copy_mem_stats() {
4084 policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
4085
4086 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
4087 create_g1_evac_summary(&_old_evac_stats));
4088 }
4089
4090 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
4091 assert(!hr->is_free(), "the region should not be free");
4092 assert(!hr->is_empty(), "the region should not be empty");
4093 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
4094
4095 if (G1VerifyBitmaps) {
4096 MemRegion mr(hr->bottom(), hr->end());
4097 concurrent_mark()->clear_range_in_prev_bitmap(mr);
4098 }
4099
4100 // Clear the card counts for this region.
4101 // Note: we only need to do this if the region is not young
4102 // (since we don't refine cards in young regions).
4103 if (!hr->is_young()) {
4104 _hot_card_cache->reset_card_counts(hr);
4105 }
4106
4107 // Reset region metadata to allow reuse.
4108 hr->hr_clear(true /* clear_space */);
4109 _policy->remset_tracker()->update_at_free(hr);
4110
4111 if (free_list != NULL) {
4112 free_list->add_ordered(hr);
4113 }
4114 }
4115
4116 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
4117 FreeRegionList* free_list) {
4118 assert(hr->is_humongous(), "this is only for humongous regions");
4119 assert(free_list != NULL, "pre-condition");
4120 hr->clear_humongous();
4121 free_region(hr, free_list);
4122 }
4123
4124 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
4125 const uint humongous_regions_removed) {
4126 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
4127 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4128 _old_set.bulk_remove(old_regions_removed);
4129 _humongous_set.bulk_remove(humongous_regions_removed);
4130 }
4131
4132 }
4133
4134 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
4135 assert(list != NULL, "list can't be null");
4136 if (!list->is_empty()) {
4137 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
4138 _hrm->insert_list_into_free_list(list);
4139 }
4140 }
4141
4142 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
4143 decrease_used(bytes);
4144 }
4145
4146 class G1FreeCollectionSetTask : public AbstractGangTask {
4147 // Helper class to keep statistics for the collection set freeing
4148 class FreeCSetStats {
4149 size_t _before_used_bytes; // Usage in regions successfully evacutate
4150 size_t _after_used_bytes; // Usage in regions failing evacuation
4151 size_t _bytes_allocated_in_old_since_last_gc; // Size of young regions turned into old
4152 size_t _failure_used_words; // Live size in failed regions
4153 size_t _failure_waste_words; // Wasted size in failed regions
4154 size_t _rs_length; // Remembered set size
4155 uint _regions_freed; // Number of regions freed
4156 public:
4157 FreeCSetStats() :
4158 _before_used_bytes(0),
4159 _after_used_bytes(0),
4160 _bytes_allocated_in_old_since_last_gc(0),
4161 _failure_used_words(0),
4162 _failure_waste_words(0),
4163 _rs_length(0),
4164 _regions_freed(0) { }
4165
4166 void merge_stats(FreeCSetStats* other) {
4167 assert(other != NULL, "invariant");
4168 _before_used_bytes += other->_before_used_bytes;
4169 _after_used_bytes += other->_after_used_bytes;
4170 _bytes_allocated_in_old_since_last_gc += other->_bytes_allocated_in_old_since_last_gc;
4171 _failure_used_words += other->_failure_used_words;
4172 _failure_waste_words += other->_failure_waste_words;
4173 _rs_length += other->_rs_length;
4174 _regions_freed += other->_regions_freed;
4175 }
4176
4177 void report(G1CollectedHeap* g1h, G1EvacuationInfo* evacuation_info) {
4178 evacuation_info->set_regions_freed(_regions_freed);
4179 evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4180
4181 g1h->decrement_summary_bytes(_before_used_bytes);
4182 g1h->alloc_buffer_stats(G1HeapRegionAttr::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4183
4184 G1Policy *policy = g1h->policy();
4185 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4186 policy->record_rs_length(_rs_length);
4187 policy->cset_regions_freed();
4188 }
4189
4190 void account_failed_region(HeapRegion* r) {
4191 size_t used_words = r->marked_bytes() / HeapWordSize;
4192 _failure_used_words += used_words;
4193 _failure_waste_words += HeapRegion::GrainWords - used_words;
4194 _after_used_bytes += r->used();
4195
4196 // When moving a young gen region to old gen, we "allocate" that whole
4197 // region there. This is in addition to any already evacuated objects.
4198 // Notify the policy about that. Old gen regions do not cause an
4199 // additional allocation: both the objects still in the region and the
4200 // ones already moved are accounted for elsewhere.
4201 if (r->is_young()) {
4202 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4203 }
4204 }
4205
4206 void account_evacuated_region(HeapRegion* r) {
4207 _before_used_bytes += r->used();
4208 _regions_freed += 1;
4209 }
4210
4211 void account_rs_length(HeapRegion* r) {
4212 _rs_length += r->rem_set()->occupied();
4213 }
4214 };
4215
4216 // Closure applied to all regions in the collection set.
4217 class FreeCSetClosure : public HeapRegionClosure {
4218 // Helper to send JFR events for regions.
4219 class JFREventForRegion {
4220 EventGCPhaseParallel _event;
4221 public:
4222 JFREventForRegion(HeapRegion* region, uint worker_id) : _event() {
4223 _event.set_gcId(GCId::current());
4224 _event.set_gcWorkerId(worker_id);
4225 if (region->is_young()) {
4226 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4227 } else {
4228 _event.set_name(G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4229 }
4230 }
4231
4232 ~JFREventForRegion() {
4233 _event.commit();
4234 }
4235 };
4236
4237 // Helper to do timing for region work.
4238 class TimerForRegion {
4239 Tickspan& _time;
4240 Ticks _start_time;
4241 public:
4242 TimerForRegion(Tickspan& time) : _time(time), _start_time(Ticks::now()) { }
4243 ~TimerForRegion() {
4244 _time += Ticks::now() - _start_time;
4245 }
4246 };
4247
4248 // FreeCSetClosure members
4249 G1CollectedHeap* _g1h;
4250 const size_t* _surviving_young_words;
4251 uint _worker_id;
4252 Tickspan _young_time;
4253 Tickspan _non_young_time;
4254 FreeCSetStats* _stats;
4255
4256 void assert_in_cset(HeapRegion* r) {
4257 assert(r->young_index_in_cset() != 0 &&
4258 (uint)r->young_index_in_cset() <= _g1h->collection_set()->young_region_length(),
4259 "Young index %u is wrong for region %u of type %s with %u young regions",
4260 r->young_index_in_cset(), r->hrm_index(), r->get_type_str(), _g1h->collection_set()->young_region_length());
4261 }
4262
4263 void handle_evacuated_region(HeapRegion* r) {
4264 assert(!r->is_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4265 stats()->account_evacuated_region(r);
4266
4267 // Free the region and and its remembered set.
4268 _g1h->free_region(r, NULL);
4269 }
4270
4271 void handle_failed_region(HeapRegion* r) {
4272 // Do some allocation statistics accounting. Regions that failed evacuation
4273 // are always made old, so there is no need to update anything in the young
4274 // gen statistics, but we need to update old gen statistics.
4275 stats()->account_failed_region(r);
4276
4277 // Update the region state due to the failed evacuation.
4278 r->handle_evacuation_failure();
4279
4280 // Add region to old set, need to hold lock.
4281 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4282 _g1h->old_set_add(r);
4283 }
4284
4285 Tickspan& timer_for_region(HeapRegion* r) {
4286 return r->is_young() ? _young_time : _non_young_time;
4287 }
4288
4289 FreeCSetStats* stats() {
4290 return _stats;
4291 }
4292 public:
4293 FreeCSetClosure(const size_t* surviving_young_words,
4294 uint worker_id,
4295 FreeCSetStats* stats) :
4296 HeapRegionClosure(),
4297 _g1h(G1CollectedHeap::heap()),
4298 _surviving_young_words(surviving_young_words),
4299 _worker_id(worker_id),
4300 _young_time(),
4301 _non_young_time(),
4302 _stats(stats) { }
4303
4304 virtual bool do_heap_region(HeapRegion* r) {
4305 assert(r->in_collection_set(), "Invariant: %u missing from CSet", r->hrm_index());
4306 JFREventForRegion event(r, _worker_id);
4307 TimerForRegion timer(timer_for_region(r));
4308
4309 _g1h->clear_region_attr(r);
4310 stats()->account_rs_length(r);
4311
4312 if (r->is_young()) {
4313 assert_in_cset(r);
4314 r->record_surv_words_in_group(_surviving_young_words[r->young_index_in_cset()]);
4315 }
4316
4317 if (r->evacuation_failed()) {
4318 handle_failed_region(r);
4319 } else {
4320 handle_evacuated_region(r);
4321 }
4322 assert(!_g1h->is_on_master_free_list(r), "sanity");
4323
4324 return false;
4325 }
4326
4327 void report_timing(Tickspan parallel_time) {
4328 G1GCPhaseTimes* pt = _g1h->phase_times();
4329 pt->record_time_secs(G1GCPhaseTimes::ParFreeCSet, _worker_id, parallel_time.seconds());
4330 if (_young_time.value() > 0) {
4331 pt->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, _worker_id, _young_time.seconds());
4332 }
4333 if (_non_young_time.value() > 0) {
4334 pt->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, _worker_id, _non_young_time.seconds());
4335 }
4336 }
4337 };
4338
4339 // G1FreeCollectionSetTask members
4340 G1CollectedHeap* _g1h;
4341 G1EvacuationInfo* _evacuation_info;
4342 FreeCSetStats* _worker_stats;
4343 HeapRegionClaimer _claimer;
4344 const size_t* _surviving_young_words;
4345 uint _active_workers;
4346
4347 FreeCSetStats* worker_stats(uint worker) {
4348 return &_worker_stats[worker];
4349 }
4350
4351 void report_statistics() {
4352 // Merge the accounting
4353 FreeCSetStats total_stats;
4354 for (uint worker = 0; worker < _active_workers; worker++) {
4355 total_stats.merge_stats(worker_stats(worker));
4356 }
4357 total_stats.report(_g1h, _evacuation_info);
4358 }
4359
4360 public:
4361 G1FreeCollectionSetTask(G1EvacuationInfo* evacuation_info, const size_t* surviving_young_words, uint active_workers) :
4362 AbstractGangTask("G1 Free Collection Set"),
4363 _g1h(G1CollectedHeap::heap()),
4364 _evacuation_info(evacuation_info),
4365 _worker_stats(NEW_C_HEAP_ARRAY(FreeCSetStats, active_workers, mtGC)),
4366 _claimer(active_workers),
4367 _surviving_young_words(surviving_young_words),
4368 _active_workers(active_workers) {
4369 for (uint worker = 0; worker < active_workers; worker++) {
4370 ::new (&_worker_stats[worker]) FreeCSetStats();
4371 }
4372 }
4373
4374 ~G1FreeCollectionSetTask() {
4375 Ticks serial_time = Ticks::now();
4376 report_statistics();
4377 for (uint worker = 0; worker < _active_workers; worker++) {
4378 _worker_stats[worker].~FreeCSetStats();
4379 }
4380 FREE_C_HEAP_ARRAY(FreeCSetStats, _worker_stats);
4381 _g1h->phase_times()->record_serial_free_cset_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
4382 }
4383
4384 virtual void work(uint worker_id) {
4385 EventGCPhaseParallel event;
4386 Ticks start = Ticks::now();
4387 FreeCSetClosure cl(_surviving_young_words, worker_id, worker_stats(worker_id));
4388 _g1h->collection_set_par_iterate_all(&cl, &_claimer, worker_id);
4389
4390 // Report the total parallel time along with some more detailed metrics.
4391 cl.report_timing(Ticks::now() - start);
4392 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ParFreeCSet));
4393 }
4394 };
4395
4396 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, G1EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4397 _eden.clear();
4398
4399 // The free collections set is split up in two tasks, the first
4400 // frees the collection set and records what regions are free,
4401 // and the second one rebuilds the free list. This proved to be
4402 // more efficient than adding a sorted list to another.
4403
4404 Ticks free_cset_start_time = Ticks::now();
4405 {
4406 uint const num_cs_regions = _collection_set.region_length();
4407 uint const num_workers = clamp(num_cs_regions, 1u, workers()->active_workers());
4408 G1FreeCollectionSetTask cl(&evacuation_info, surviving_young_words, num_workers);
4409
4410 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u (%u)",
4411 cl.name(), num_workers, num_cs_regions, num_regions());
4412 workers()->run_task(&cl, num_workers);
4413 }
4414
4415 Ticks free_cset_end_time = Ticks::now();
4416 phase_times()->record_total_free_cset_time_ms((free_cset_end_time - free_cset_start_time).seconds() * 1000.0);
4417
4418 // Now rebuild the free region list.
4419 hrm()->rebuild_free_list(workers());
4420 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - free_cset_end_time).seconds() * 1000.0);
4421
4422 collection_set->clear();
4423 }
4424
4425 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4426 private:
4427 FreeRegionList* _free_region_list;
4428 HeapRegionSet* _proxy_set;
4429 uint _humongous_objects_reclaimed;
4430 uint _humongous_regions_reclaimed;
4431 size_t _freed_bytes;
4432 public:
4433
4434 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4435 _free_region_list(free_region_list), _proxy_set(NULL), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4436 }
4437
4438 virtual bool do_heap_region(HeapRegion* r) {
4439 if (!r->is_starts_humongous()) {
4440 return false;
4441 }
4442
4443 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4444
4445 oop obj = (oop)r->bottom();
4446 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4447
4448 // The following checks whether the humongous object is live are sufficient.
4449 // The main additional check (in addition to having a reference from the roots
4450 // or the young gen) is whether the humongous object has a remembered set entry.
4451 //
4452 // A humongous object cannot be live if there is no remembered set for it
4453 // because:
4454 // - there can be no references from within humongous starts regions referencing
4455 // the object because we never allocate other objects into them.
4456 // (I.e. there are no intra-region references that may be missed by the
4457 // remembered set)
4458 // - as soon there is a remembered set entry to the humongous starts region
4459 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4460 // until the end of a concurrent mark.
4461 //
4462 // It is not required to check whether the object has been found dead by marking
4463 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4464 // all objects allocated during that time are considered live.
4465 // SATB marking is even more conservative than the remembered set.
4466 // So if at this point in the collection there is no remembered set entry,
4467 // nobody has a reference to it.
4468 // At the start of collection we flush all refinement logs, and remembered sets
4469 // are completely up-to-date wrt to references to the humongous object.
4470 //
4471 // Other implementation considerations:
4472 // - never consider object arrays at this time because they would pose
4473 // considerable effort for cleaning up the the remembered sets. This is
4474 // required because stale remembered sets might reference locations that
4475 // are currently allocated into.
4476 uint region_idx = r->hrm_index();
4477 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4478 !r->rem_set()->is_empty()) {
4479 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",
4480 region_idx,
4481 (size_t)obj->size() * HeapWordSize,
4482 p2i(r->bottom()),
4483 r->rem_set()->occupied(),
4484 r->rem_set()->strong_code_roots_list_length(),
4485 next_bitmap->is_marked(r->bottom()),
4486 g1h->is_humongous_reclaim_candidate(region_idx),
4487 obj->is_typeArray()
4488 );
4489 return false;
4490 }
4491
4492 guarantee(obj->is_typeArray(),
4493 "Only eagerly reclaiming type arrays is supported, but the object "
4494 PTR_FORMAT " is not.", p2i(r->bottom()));
4495
4496 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",
4497 region_idx,
4498 (size_t)obj->size() * HeapWordSize,
4499 p2i(r->bottom()),
4500 r->rem_set()->occupied(),
4501 r->rem_set()->strong_code_roots_list_length(),
4502 next_bitmap->is_marked(r->bottom()),
4503 g1h->is_humongous_reclaim_candidate(region_idx),
4504 obj->is_typeArray()
4505 );
4506
4507 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4508 cm->humongous_object_eagerly_reclaimed(r);
4509 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4510 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4511 region_idx,
4512 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4513 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4514 _humongous_objects_reclaimed++;
4515 do {
4516 HeapRegion* next = g1h->next_region_in_humongous(r);
4517 _freed_bytes += r->used();
4518 r->set_containing_set(NULL);
4519 _humongous_regions_reclaimed++;
4520 g1h->free_humongous_region(r, _free_region_list);
4521 r = next;
4522 } while (r != NULL);
4523
4524 return false;
4525 }
4526
4527 uint humongous_objects_reclaimed() {
4528 return _humongous_objects_reclaimed;
4529 }
4530
4531 uint humongous_regions_reclaimed() {
4532 return _humongous_regions_reclaimed;
4533 }
4534
4535 size_t bytes_freed() const {
4536 return _freed_bytes;
4537 }
4538 };
4539
4540 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4541 assert_at_safepoint_on_vm_thread();
4542
4543 if (!G1EagerReclaimHumongousObjects ||
4544 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4545 phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4546 return;
4547 }
4548
4549 double start_time = os::elapsedTime();
4550
4551 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4552
4553 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4554 heap_region_iterate(&cl);
4555
4556 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4557
4558 G1HRPrinter* hrp = hr_printer();
4559 if (hrp->is_active()) {
4560 FreeRegionListIterator iter(&local_cleanup_list);
4561 while (iter.more_available()) {
4562 HeapRegion* hr = iter.get_next();
4563 hrp->cleanup(hr);
4564 }
4565 }
4566
4567 prepend_to_freelist(&local_cleanup_list);
4568 decrement_summary_bytes(cl.bytes_freed());
4569
4570 phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4571 cl.humongous_objects_reclaimed());
4572 }
4573
4574 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4575 public:
4576 virtual bool do_heap_region(HeapRegion* r) {
4577 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4578 G1CollectedHeap::heap()->clear_region_attr(r);
4579 r->clear_young_index_in_cset();
4580 return false;
4581 }
4582 };
4583
4584 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4585 G1AbandonCollectionSetClosure cl;
4586 collection_set_iterate_all(&cl);
4587
4588 collection_set->clear();
4589 collection_set->stop_incremental_building();
4590 }
4591
4592 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4593 return _allocator->is_retained_old_region(hr);
4594 }
4595
4596 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4597 _eden.add(hr);
4598 _policy->set_region_eden(hr);
4599 }
4600
4601 #ifdef ASSERT
4602
4603 class NoYoungRegionsClosure: public HeapRegionClosure {
4604 private:
4605 bool _success;
4606 public:
4607 NoYoungRegionsClosure() : _success(true) { }
4608 bool do_heap_region(HeapRegion* r) {
4609 if (r->is_young()) {
4610 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4611 p2i(r->bottom()), p2i(r->end()));
4612 _success = false;
4613 }
4614 return false;
4615 }
4616 bool success() { return _success; }
4617 };
4618
4619 bool G1CollectedHeap::check_young_list_empty() {
4620 bool ret = (young_regions_count() == 0);
4621
4622 NoYoungRegionsClosure closure;
4623 heap_region_iterate(&closure);
4624 ret = ret && closure.success();
4625
4626 return ret;
4627 }
4628
4629 #endif // ASSERT
4630
4631 class TearDownRegionSetsClosure : public HeapRegionClosure {
4632 HeapRegionSet *_old_set;
4633
4634 public:
4635 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4636
4637 bool do_heap_region(HeapRegion* r) {
4638 if (r->is_old()) {
4639 _old_set->remove(r);
4640 } else if(r->is_young()) {
4641 r->uninstall_surv_rate_group();
4642 } else {
4643 // We ignore free regions, we'll empty the free list afterwards.
4644 // We ignore humongous and archive regions, we're not tearing down these
4645 // sets.
4646 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4647 "it cannot be another type");
4648 }
4649 return false;
4650 }
4651
4652 ~TearDownRegionSetsClosure() {
4653 assert(_old_set->is_empty(), "post-condition");
4654 }
4655 };
4656
4657 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4658 assert_at_safepoint_on_vm_thread();
4659
4660 if (!free_list_only) {
4661 TearDownRegionSetsClosure cl(&_old_set);
4662 heap_region_iterate(&cl);
4663
4664 // Note that emptying the _young_list is postponed and instead done as
4665 // the first step when rebuilding the regions sets again. The reason for
4666 // this is that during a full GC string deduplication needs to know if
4667 // a collected region was young or old when the full GC was initiated.
4668 }
4669 _hrm->remove_all_free_regions();
4670 }
4671
4672 void G1CollectedHeap::increase_used(size_t bytes) {
4673 _summary_bytes_used += bytes;
4674 }
4675
4676 void G1CollectedHeap::decrease_used(size_t bytes) {
4677 assert(_summary_bytes_used >= bytes,
4678 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4679 _summary_bytes_used, bytes);
4680 _summary_bytes_used -= bytes;
4681 }
4682
4683 void G1CollectedHeap::set_used(size_t bytes) {
4684 _summary_bytes_used = bytes;
4685 }
4686
4687 class RebuildRegionSetsClosure : public HeapRegionClosure {
4688 private:
4689 bool _free_list_only;
4690
4691 HeapRegionSet* _old_set;
4692 HeapRegionManager* _hrm;
4693
4694 size_t _total_used;
4695
4696 public:
4697 RebuildRegionSetsClosure(bool free_list_only,
4698 HeapRegionSet* old_set,
4699 HeapRegionManager* hrm) :
4700 _free_list_only(free_list_only),
4701 _old_set(old_set), _hrm(hrm), _total_used(0) {
4702 assert(_hrm->num_free_regions() == 0, "pre-condition");
4703 if (!free_list_only) {
4704 assert(_old_set->is_empty(), "pre-condition");
4705 }
4706 }
4707
4708 bool do_heap_region(HeapRegion* r) {
4709 if (r->is_empty()) {
4710 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4711 // Add free regions to the free list
4712 r->set_free();
4713 _hrm->insert_into_free_list(r);
4714 } else if (!_free_list_only) {
4715 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4716
4717 if (r->is_archive() || r->is_humongous()) {
4718 // We ignore archive and humongous regions. We left these sets unchanged.
4719 } else {
4720 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4721 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4722 r->move_to_old();
4723 _old_set->add(r);
4724 }
4725 _total_used += r->used();
4726 }
4727
4728 return false;
4729 }
4730
4731 size_t total_used() {
4732 return _total_used;
4733 }
4734 };
4735
4736 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4737 assert_at_safepoint_on_vm_thread();
4738
4739 if (!free_list_only) {
4740 _eden.clear();
4741 _survivor.clear();
4742 }
4743
4744 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4745 heap_region_iterate(&cl);
4746
4747 if (!free_list_only) {
4748 set_used(cl.total_used());
4749 if (_archive_allocator != NULL) {
4750 _archive_allocator->clear_used();
4751 }
4752 }
4753 assert_used_and_recalculate_used_equal(this);
4754 }
4755
4756 // Methods for the mutator alloc region
4757
4758 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4759 bool force,
4760 uint node_index) {
4761 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4762 bool should_allocate = policy()->should_allocate_mutator_region();
4763 if (force || should_allocate) {
4764 HeapRegion* new_alloc_region = new_region(word_size,
4765 HeapRegionType::Eden,
4766 false /* do_expand */,
4767 node_index);
4768 if (new_alloc_region != NULL) {
4769 set_region_short_lived_locked(new_alloc_region);
4770 _hr_printer.alloc(new_alloc_region, !should_allocate);
4771 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4772 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4773 return new_alloc_region;
4774 }
4775 }
4776 return NULL;
4777 }
4778
4779 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4780 size_t allocated_bytes) {
4781 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4782 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4783
4784 collection_set()->add_eden_region(alloc_region);
4785 increase_used(allocated_bytes);
4786 _eden.add_used_bytes(allocated_bytes);
4787 _hr_printer.retire(alloc_region);
4788
4789 // We update the eden sizes here, when the region is retired,
4790 // instead of when it's allocated, since this is the point that its
4791 // used space has been recorded in _summary_bytes_used.
4792 g1mm()->update_eden_size();
4793 }
4794
4795 // Methods for the GC alloc regions
4796
4797 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4798 if (dest.is_old()) {
4799 return true;
4800 } else {
4801 return survivor_regions_count() < policy()->max_survivor_regions();
4802 }
4803 }
4804
4805 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4806 assert(FreeList_lock->owned_by_self(), "pre-condition");
4807
4808 if (!has_more_regions(dest)) {
4809 return NULL;
4810 }
4811
4812 HeapRegionType type;
4813 if (dest.is_young()) {
4814 type = HeapRegionType::Survivor;
4815 } else {
4816 type = HeapRegionType::Old;
4817 }
4818
4819 HeapRegion* new_alloc_region = new_region(word_size,
4820 type,
4821 true /* do_expand */,
4822 node_index);
4823
4824 if (new_alloc_region != NULL) {
4825 if (type.is_survivor()) {
4826 new_alloc_region->set_survivor();
4827 _survivor.add(new_alloc_region);
4828 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4829 } else {
4830 new_alloc_region->set_old();
4831 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4832 }
4833 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4834 register_region_with_region_attr(new_alloc_region);
4835 _hr_printer.alloc(new_alloc_region);
4836 return new_alloc_region;
4837 }
4838 return NULL;
4839 }
4840
4841 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4842 size_t allocated_bytes,
4843 G1HeapRegionAttr dest) {
4844 _bytes_used_during_gc += allocated_bytes;
4845 if (dest.is_old()) {
4846 old_set_add(alloc_region);
4847 } else {
4848 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4849 _survivor.add_used_bytes(allocated_bytes);
4850 }
4851
4852 bool const during_im = collector_state()->in_initial_mark_gc();
4853 if (during_im && allocated_bytes > 0) {
4854 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4855 }
4856 _hr_printer.retire(alloc_region);
4857 }
4858
4859 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4860 bool expanded = false;
4861 uint index = _hrm->find_highest_free(&expanded);
4862
4863 if (index != G1_NO_HRM_INDEX) {
4864 if (expanded) {
4865 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4866 HeapRegion::GrainWords * HeapWordSize);
4867 }
4868 return _hrm->allocate_free_regions_starting_at(index, 1);
4869 }
4870 return NULL;
4871 }
4872
4873 // Optimized nmethod scanning
4874
4875 class RegisterNMethodOopClosure: public OopClosure {
4876 G1CollectedHeap* _g1h;
4877 nmethod* _nm;
4878
4879 template <class T> void do_oop_work(T* p) {
4880 T heap_oop = RawAccess<>::oop_load(p);
4881 if (!CompressedOops::is_null(heap_oop)) {
4882 oop obj = CompressedOops::decode_not_null(heap_oop);
4883 HeapRegion* hr = _g1h->heap_region_containing(obj);
4884 assert(!hr->is_continues_humongous(),
4885 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4886 " starting at " HR_FORMAT,
4887 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4888
4889 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4890 hr->add_strong_code_root_locked(_nm);
4891 }
4892 }
4893
4894 public:
4895 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4896 _g1h(g1h), _nm(nm) {}
4897
4898 void do_oop(oop* p) { do_oop_work(p); }
4899 void do_oop(narrowOop* p) { do_oop_work(p); }
4900 };
4901
4902 class UnregisterNMethodOopClosure: public OopClosure {
4903 G1CollectedHeap* _g1h;
4904 nmethod* _nm;
4905
4906 template <class T> void do_oop_work(T* p) {
4907 T heap_oop = RawAccess<>::oop_load(p);
4908 if (!CompressedOops::is_null(heap_oop)) {
4909 oop obj = CompressedOops::decode_not_null(heap_oop);
4910 HeapRegion* hr = _g1h->heap_region_containing(obj);
4911 assert(!hr->is_continues_humongous(),
4912 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4913 " starting at " HR_FORMAT,
4914 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4915
4916 hr->remove_strong_code_root(_nm);
4917 }
4918 }
4919
4920 public:
4921 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4922 _g1h(g1h), _nm(nm) {}
4923
4924 void do_oop(oop* p) { do_oop_work(p); }
4925 void do_oop(narrowOop* p) { do_oop_work(p); }
4926 };
4927
4928 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4929 guarantee(nm != NULL, "sanity");
4930 RegisterNMethodOopClosure reg_cl(this, nm);
4931 nm->oops_do(®_cl);
4932 }
4933
4934 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4935 guarantee(nm != NULL, "sanity");
4936 UnregisterNMethodOopClosure reg_cl(this, nm);
4937 nm->oops_do(®_cl, true);
4938 }
4939
4940 void G1CollectedHeap::purge_code_root_memory() {
4941 double purge_start = os::elapsedTime();
4942 G1CodeRootSet::purge();
4943 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4944 phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4945 }
4946
4947 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4948 G1CollectedHeap* _g1h;
4949
4950 public:
4951 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4952 _g1h(g1h) {}
4953
4954 void do_code_blob(CodeBlob* cb) {
4955 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4956 if (nm == NULL) {
4957 return;
4958 }
4959
4960 _g1h->register_nmethod(nm);
4961 }
4962 };
4963
4964 void G1CollectedHeap::rebuild_strong_code_roots() {
4965 RebuildStrongCodeRootClosure blob_cl(this);
4966 CodeCache::blobs_do(&blob_cl);
4967 }
4968
4969 void G1CollectedHeap::initialize_serviceability() {
4970 _g1mm->initialize_serviceability();
4971 }
4972
4973 MemoryUsage G1CollectedHeap::memory_usage() {
4974 return _g1mm->memory_usage();
4975 }
4976
4977 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4978 return _g1mm->memory_managers();
4979 }
4980
4981 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4982 return _g1mm->memory_pools();
4983 }