1 /*
2 * Copyright (c) 2001, 2018, 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/g1BarrierSet.hpp"
33 #include "gc/g1/g1CollectedHeap.inline.hpp"
34 #include "gc/g1/g1CollectionSet.hpp"
35 #include "gc/g1/g1CollectorPolicy.hpp"
36 #include "gc/g1/g1CollectorState.hpp"
37 #include "gc/g1/g1ConcurrentRefine.hpp"
38 #include "gc/g1/g1ConcurrentRefineThread.hpp"
39 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
40 #include "gc/g1/g1EvacStats.inline.hpp"
41 #include "gc/g1/g1FullCollector.hpp"
42 #include "gc/g1/g1GCPhaseTimes.hpp"
43 #include "gc/g1/g1HeapSizingPolicy.hpp"
44 #include "gc/g1/g1HeapTransition.hpp"
45 #include "gc/g1/g1HeapVerifier.hpp"
46 #include "gc/g1/g1HotCardCache.hpp"
47 #include "gc/g1/g1MemoryPool.hpp"
48 #include "gc/g1/g1OopClosures.inline.hpp"
49 #include "gc/g1/g1ParScanThreadState.inline.hpp"
50 #include "gc/g1/g1Policy.hpp"
51 #include "gc/g1/g1RegionToSpaceMapper.hpp"
52 #include "gc/g1/g1RemSet.hpp"
53 #include "gc/g1/g1RootClosures.hpp"
54 #include "gc/g1/g1RootProcessor.hpp"
55 #include "gc/g1/g1SATBMarkQueueSet.hpp"
56 #include "gc/g1/g1StringDedup.hpp"
57 #include "gc/g1/g1ThreadLocalData.hpp"
58 #include "gc/g1/g1YCTypes.hpp"
59 #include "gc/g1/g1YoungRemSetSamplingThread.hpp"
60 #include "gc/g1/g1VMOperations.hpp"
61 #include "gc/g1/heapRegion.inline.hpp"
62 #include "gc/g1/heapRegionRemSet.hpp"
63 #include "gc/g1/heapRegionSet.inline.hpp"
64 #include "gc/shared/gcBehaviours.hpp"
65 #include "gc/shared/gcHeapSummary.hpp"
66 #include "gc/shared/gcId.hpp"
67 #include "gc/shared/gcLocker.hpp"
68 #include "gc/shared/gcTimer.hpp"
69 #include "gc/shared/gcTrace.hpp"
70 #include "gc/shared/gcTraceTime.inline.hpp"
71 #include "gc/shared/generationSpec.hpp"
72 #include "gc/shared/isGCActiveMark.hpp"
73 #include "gc/shared/oopStorageParState.hpp"
74 #include "gc/shared/parallelCleaning.hpp"
75 #include "gc/shared/preservedMarks.inline.hpp"
76 #include "gc/shared/suspendibleThreadSet.hpp"
77 #include "gc/shared/referenceProcessor.inline.hpp"
78 #include "gc/shared/taskqueue.inline.hpp"
79 #include "gc/shared/weakProcessor.inline.hpp"
80 #include "gc/shared/workerPolicy.hpp"
81 #include "logging/log.hpp"
82 #include "memory/allocation.hpp"
83 #include "memory/iterator.hpp"
84 #include "memory/resourceArea.hpp"
85 #include "oops/access.inline.hpp"
86 #include "oops/compressedOops.inline.hpp"
87 #include "oops/oop.inline.hpp"
88 #include "runtime/atomic.hpp"
89 #include "runtime/flags/flagSetting.hpp"
90 #include "runtime/handles.inline.hpp"
91 #include "runtime/init.hpp"
92 #include "runtime/orderAccess.hpp"
93 #include "runtime/threadSMR.hpp"
94 #include "runtime/vmThread.hpp"
95 #include "utilities/align.hpp"
96 #include "utilities/globalDefinitions.hpp"
97 #include "utilities/stack.inline.hpp"
98
99 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
100
101 // INVARIANTS/NOTES
102 //
103 // All allocation activity covered by the G1CollectedHeap interface is
104 // serialized by acquiring the HeapLock. This happens in mem_allocate
105 // and allocate_new_tlab, which are the "entry" points to the
106 // allocation code from the rest of the JVM. (Note that this does not
107 // apply to TLAB allocation, which is not part of this interface: it
108 // is done by clients of this interface.)
109
110 class RedirtyLoggedCardTableEntryClosure : public CardTableEntryClosure {
111 private:
112 size_t _num_dirtied;
113 G1CollectedHeap* _g1h;
114 G1CardTable* _g1_ct;
115
116 HeapRegion* region_for_card(jbyte* card_ptr) const {
117 return _g1h->heap_region_containing(_g1_ct->addr_for(card_ptr));
118 }
119
120 bool will_become_free(HeapRegion* hr) const {
121 // A region will be freed by free_collection_set if the region is in the
122 // collection set and has not had an evacuation failure.
123 return _g1h->is_in_cset(hr) && !hr->evacuation_failed();
124 }
125
126 public:
127 RedirtyLoggedCardTableEntryClosure(G1CollectedHeap* g1h) : CardTableEntryClosure(),
128 _num_dirtied(0), _g1h(g1h), _g1_ct(g1h->card_table()) { }
129
130 bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
131 HeapRegion* hr = region_for_card(card_ptr);
132
133 // Should only dirty cards in regions that won't be freed.
134 if (!will_become_free(hr)) {
135 *card_ptr = G1CardTable::dirty_card_val();
136 _num_dirtied++;
137 }
138
139 return true;
140 }
141
142 size_t num_dirtied() const { return _num_dirtied; }
143 };
144
145
146 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
147 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
148 }
149
150 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
151 // The from card cache is not the memory that is actually committed. So we cannot
152 // take advantage of the zero_filled parameter.
153 reset_from_card_cache(start_idx, num_regions);
154 }
155
156
157 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
158 MemRegion mr) {
159 return new HeapRegion(hrs_index, bot(), mr);
160 }
161
162 // Private methods.
163
164 HeapRegion* G1CollectedHeap::new_region(size_t word_size, bool is_old, bool do_expand) {
165 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
166 "the only time we use this to allocate a humongous region is "
167 "when we are allocating a single humongous region");
168
169 HeapRegion* res = _hrm.allocate_free_region(is_old);
170
171 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
172 // Currently, only attempts to allocate GC alloc regions set
173 // do_expand to true. So, we should only reach here during a
174 // safepoint. If this assumption changes we might have to
175 // reconsider the use of _expand_heap_after_alloc_failure.
176 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
177
178 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
179 word_size * HeapWordSize);
180
181 if (expand(word_size * HeapWordSize)) {
182 // Given that expand() succeeded in expanding the heap, and we
183 // always expand the heap by an amount aligned to the heap
184 // region size, the free list should in theory not be empty.
185 // In either case allocate_free_region() will check for NULL.
186 res = _hrm.allocate_free_region(is_old);
187 } else {
188 _expand_heap_after_alloc_failure = false;
189 }
190 }
191 return res;
192 }
193
194 HeapWord*
195 G1CollectedHeap::humongous_obj_allocate_initialize_regions(uint first,
196 uint num_regions,
197 size_t word_size) {
198 assert(first != G1_NO_HRM_INDEX, "pre-condition");
199 assert(is_humongous(word_size), "word_size should be humongous");
200 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
201
202 // Index of last region in the series.
203 uint last = first + num_regions - 1;
204
205 // We need to initialize the region(s) we just discovered. This is
206 // a bit tricky given that it can happen concurrently with
207 // refinement threads refining cards on these regions and
208 // potentially wanting to refine the BOT as they are scanning
209 // those cards (this can happen shortly after a cleanup; see CR
210 // 6991377). So we have to set up the region(s) carefully and in
211 // a specific order.
212
213 // The word size sum of all the regions we will allocate.
214 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
215 assert(word_size <= word_size_sum, "sanity");
216
217 // This will be the "starts humongous" region.
218 HeapRegion* first_hr = region_at(first);
219 // The header of the new object will be placed at the bottom of
220 // the first region.
221 HeapWord* new_obj = first_hr->bottom();
222 // This will be the new top of the new object.
223 HeapWord* obj_top = new_obj + word_size;
224
225 // First, we need to zero the header of the space that we will be
226 // allocating. When we update top further down, some refinement
227 // threads might try to scan the region. By zeroing the header we
228 // ensure that any thread that will try to scan the region will
229 // come across the zero klass word and bail out.
230 //
231 // NOTE: It would not have been correct to have used
232 // CollectedHeap::fill_with_object() and make the space look like
233 // an int array. The thread that is doing the allocation will
234 // later update the object header to a potentially different array
235 // type and, for a very short period of time, the klass and length
236 // fields will be inconsistent. This could cause a refinement
237 // thread to calculate the object size incorrectly.
238 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
239
240 // Next, pad out the unused tail of the last region with filler
241 // objects, for improved usage accounting.
242 // How many words we use for filler objects.
243 size_t word_fill_size = word_size_sum - word_size;
244
245 // How many words memory we "waste" which cannot hold a filler object.
246 size_t words_not_fillable = 0;
247
248 if (word_fill_size >= min_fill_size()) {
249 fill_with_objects(obj_top, word_fill_size);
250 } else if (word_fill_size > 0) {
251 // We have space to fill, but we cannot fit an object there.
252 words_not_fillable = word_fill_size;
253 word_fill_size = 0;
254 }
255
256 // We will set up the first region as "starts humongous". This
257 // will also update the BOT covering all the regions to reflect
258 // that there is a single object that starts at the bottom of the
259 // first region.
260 first_hr->set_starts_humongous(obj_top, word_fill_size);
261 _g1_policy->remset_tracker()->update_at_allocate(first_hr);
262 // Then, if there are any, we will set up the "continues
263 // humongous" regions.
264 HeapRegion* hr = NULL;
265 for (uint i = first + 1; i <= last; ++i) {
266 hr = region_at(i);
267 hr->set_continues_humongous(first_hr);
268 _g1_policy->remset_tracker()->update_at_allocate(hr);
269 }
270
271 // Up to this point no concurrent thread would have been able to
272 // do any scanning on any region in this series. All the top
273 // fields still point to bottom, so the intersection between
274 // [bottom,top] and [card_start,card_end] will be empty. Before we
275 // update the top fields, we'll do a storestore to make sure that
276 // no thread sees the update to top before the zeroing of the
277 // object header and the BOT initialization.
278 OrderAccess::storestore();
279
280 // Now, we will update the top fields of the "continues humongous"
281 // regions except the last one.
282 for (uint i = first; i < last; ++i) {
283 hr = region_at(i);
284 hr->set_top(hr->end());
285 }
286
287 hr = region_at(last);
288 // If we cannot fit a filler object, we must set top to the end
289 // of the humongous object, otherwise we cannot iterate the heap
290 // and the BOT will not be complete.
291 hr->set_top(hr->end() - words_not_fillable);
292
293 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
294 "obj_top should be in last region");
295
296 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
297
298 assert(words_not_fillable == 0 ||
299 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
300 "Miscalculation in humongous allocation");
301
302 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
303
304 for (uint i = first; i <= last; ++i) {
305 hr = region_at(i);
306 _humongous_set.add(hr);
307 _hr_printer.alloc(hr);
308 }
309
310 return new_obj;
311 }
312
313 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
314 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
315 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
316 }
317
318 // If could fit into free regions w/o expansion, try.
319 // Otherwise, if can expand, do so.
320 // Otherwise, if using ex regions might help, try with ex given back.
321 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
322 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
323
324 _verifier->verify_region_sets_optional();
325
326 uint first = G1_NO_HRM_INDEX;
327 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
328
329 if (obj_regions == 1) {
330 // Only one region to allocate, try to use a fast path by directly allocating
331 // from the free lists. Do not try to expand here, we will potentially do that
332 // later.
333 HeapRegion* hr = new_region(word_size, true /* is_old */, false /* do_expand */);
334 if (hr != NULL) {
335 first = hr->hrm_index();
336 }
337 } else {
338 // Policy: Try only empty regions (i.e. already committed first). Maybe we
339 // are lucky enough to find some.
340 first = _hrm.find_contiguous_only_empty(obj_regions);
341 if (first != G1_NO_HRM_INDEX) {
342 _hrm.allocate_free_regions_starting_at(first, obj_regions);
343 }
344 }
345
346 if (first == G1_NO_HRM_INDEX) {
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, try expansion.
350 first = _hrm.find_contiguous_empty_or_unavailable(obj_regions);
351 if (first != G1_NO_HRM_INDEX) {
352 // We found something. Make sure these regions are committed, i.e. expand
353 // the heap. Alternatively we could do a defragmentation GC.
354 log_debug(gc, ergo, heap)("Attempt heap expansion (humongous allocation request failed). Allocation request: " SIZE_FORMAT "B",
355 word_size * HeapWordSize);
356
357 _hrm.expand_at(first, obj_regions, workers());
358 g1_policy()->record_new_heap_size(num_regions());
359
360 #ifdef ASSERT
361 for (uint i = first; i < first + obj_regions; ++i) {
362 HeapRegion* hr = region_at(i);
363 assert(hr->is_free(), "sanity");
364 assert(hr->is_empty(), "sanity");
365 assert(is_on_master_free_list(hr), "sanity");
366 }
367 #endif
368 _hrm.allocate_free_regions_starting_at(first, obj_regions);
369 } else {
370 // Policy: Potentially trigger a defragmentation GC.
371 }
372 }
373
374 HeapWord* result = NULL;
375 if (first != G1_NO_HRM_INDEX) {
376 result = humongous_obj_allocate_initialize_regions(first, obj_regions, word_size);
377 assert(result != NULL, "it should always return a valid result");
378
379 // A successful humongous object allocation changes the used space
380 // information of the old generation so we need to recalculate the
381 // sizes and update the jstat counters here.
382 g1mm()->update_sizes();
383 }
384
385 _verifier->verify_region_sets_optional();
386
387 return result;
388 }
389
390 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
391 size_t requested_size,
392 size_t* actual_size) {
393 assert_heap_not_locked_and_not_at_safepoint();
394 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
395
396 return attempt_allocation(min_size, requested_size, actual_size);
397 }
398
399 HeapWord*
400 G1CollectedHeap::mem_allocate(size_t word_size,
401 bool* gc_overhead_limit_was_exceeded) {
402 assert_heap_not_locked_and_not_at_safepoint();
403
404 if (is_humongous(word_size)) {
405 return attempt_allocation_humongous(word_size);
406 }
407 size_t dummy = 0;
408 return attempt_allocation(word_size, word_size, &dummy);
409 }
410
411 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
412 ResourceMark rm; // For retrieving the thread names in log messages.
413
414 // Make sure you read the note in attempt_allocation_humongous().
415
416 assert_heap_not_locked_and_not_at_safepoint();
417 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
418 "be called for humongous allocation requests");
419
420 // We should only get here after the first-level allocation attempt
421 // (attempt_allocation()) failed to allocate.
422
423 // We will loop until a) we manage to successfully perform the
424 // allocation or b) we successfully schedule a collection which
425 // fails to perform the allocation. b) is the only case when we'll
426 // return NULL.
427 HeapWord* result = NULL;
428 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
429 bool should_try_gc;
430 uint gc_count_before;
431
432 {
433 MutexLockerEx x(Heap_lock);
434 result = _allocator->attempt_allocation_locked(word_size);
435 if (result != NULL) {
436 return result;
437 }
438
439 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
440 // This is different to when only GCLocker::needs_gc() is set: try to avoid
441 // waiting because the GCLocker is active to not wait too long.
442 if (GCLocker::is_active_and_needs_gc() && g1_policy()->can_expand_young_list()) {
443 // No need for an ergo message here, can_expand_young_list() does this when
444 // it returns true.
445 result = _allocator->attempt_allocation_force(word_size);
446 if (result != NULL) {
447 return result;
448 }
449 }
450 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
451 // the GCLocker initiated GC has been performed and then retry. This includes
452 // the case when the GC Locker is not active but has not been performed.
453 should_try_gc = !GCLocker::needs_gc();
454 // Read the GC count while still holding the Heap_lock.
455 gc_count_before = total_collections();
456 }
457
458 if (should_try_gc) {
459 bool succeeded;
460 result = do_collection_pause(word_size, gc_count_before, &succeeded,
461 GCCause::_g1_inc_collection_pause);
462 if (result != NULL) {
463 assert(succeeded, "only way to get back a non-NULL result");
464 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
465 Thread::current()->name(), p2i(result));
466 return result;
467 }
468
469 if (succeeded) {
470 // We successfully scheduled a collection which failed to allocate. No
471 // point in trying to allocate further. We'll just return NULL.
472 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
473 SIZE_FORMAT " words", Thread::current()->name(), word_size);
474 return NULL;
475 }
476 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
477 Thread::current()->name(), word_size);
478 } else {
479 // Failed to schedule a collection.
480 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
481 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
482 SIZE_FORMAT " words", Thread::current()->name(), word_size);
483 return NULL;
484 }
485 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
486 // The GCLocker is either active or the GCLocker initiated
487 // GC has not yet been performed. Stall until it is and
488 // then retry the allocation.
489 GCLocker::stall_until_clear();
490 gclocker_retry_count += 1;
491 }
492
493 // We can reach here if we were unsuccessful in scheduling a
494 // collection (because another thread beat us to it) or if we were
495 // stalled due to the GC locker. In either can we should retry the
496 // allocation attempt in case another thread successfully
497 // performed a collection and reclaimed enough space. We do the
498 // first attempt (without holding the Heap_lock) here and the
499 // follow-on attempt will be at the start of the next loop
500 // iteration (after taking the Heap_lock).
501 size_t dummy = 0;
502 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
503 if (result != NULL) {
504 return result;
505 }
506
507 // Give a warning if we seem to be looping forever.
508 if ((QueuedAllocationWarningCount > 0) &&
509 (try_count % QueuedAllocationWarningCount == 0)) {
510 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
511 Thread::current()->name(), try_count, word_size);
512 }
513 }
514
515 ShouldNotReachHere();
516 return NULL;
517 }
518
519 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
520 assert_at_safepoint_on_vm_thread();
521 if (_archive_allocator == NULL) {
522 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
523 }
524 }
525
526 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
527 // Allocations in archive regions cannot be of a size that would be considered
528 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
529 // may be different at archive-restore time.
530 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
531 }
532
533 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
534 assert_at_safepoint_on_vm_thread();
535 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
536 if (is_archive_alloc_too_large(word_size)) {
537 return NULL;
538 }
539 return _archive_allocator->archive_mem_allocate(word_size);
540 }
541
542 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
543 size_t end_alignment_in_bytes) {
544 assert_at_safepoint_on_vm_thread();
545 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
546
547 // Call complete_archive to do the real work, filling in the MemRegion
548 // array with the archive regions.
549 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
550 delete _archive_allocator;
551 _archive_allocator = NULL;
552 }
553
554 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
555 assert(ranges != NULL, "MemRegion array NULL");
556 assert(count != 0, "No MemRegions provided");
557 MemRegion reserved = _hrm.reserved();
558 for (size_t i = 0; i < count; i++) {
559 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
560 return false;
561 }
562 }
563 return true;
564 }
565
566 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
567 size_t count,
568 bool open) {
569 assert(!is_init_completed(), "Expect to be called at JVM init time");
570 assert(ranges != NULL, "MemRegion array NULL");
571 assert(count != 0, "No MemRegions provided");
572 MutexLockerEx x(Heap_lock);
573
574 MemRegion reserved = _hrm.reserved();
575 HeapWord* prev_last_addr = NULL;
576 HeapRegion* prev_last_region = NULL;
577
578 // Temporarily disable pretouching of heap pages. This interface is used
579 // when mmap'ing archived heap data in, so pre-touching is wasted.
580 FlagSetting fs(AlwaysPreTouch, false);
581
582 // Enable archive object checking used by G1MarkSweep. We have to let it know
583 // about each archive range, so that objects in those ranges aren't marked.
584 G1ArchiveAllocator::enable_archive_object_check();
585
586 // For each specified MemRegion range, allocate the corresponding G1
587 // regions and mark them as archive regions. We expect the ranges
588 // in ascending starting address order, without overlap.
589 for (size_t i = 0; i < count; i++) {
590 MemRegion curr_range = ranges[i];
591 HeapWord* start_address = curr_range.start();
592 size_t word_size = curr_range.word_size();
593 HeapWord* last_address = curr_range.last();
594 size_t commits = 0;
595
596 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
597 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
598 p2i(start_address), p2i(last_address));
599 guarantee(start_address > prev_last_addr,
600 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
601 p2i(start_address), p2i(prev_last_addr));
602 prev_last_addr = last_address;
603
604 // Check for ranges that start in the same G1 region in which the previous
605 // range ended, and adjust the start address so we don't try to allocate
606 // the same region again. If the current range is entirely within that
607 // region, skip it, just adjusting the recorded top.
608 HeapRegion* start_region = _hrm.addr_to_region(start_address);
609 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
610 start_address = start_region->end();
611 if (start_address > last_address) {
612 increase_used(word_size * HeapWordSize);
613 start_region->set_top(last_address + 1);
614 continue;
615 }
616 start_region->set_top(start_address);
617 curr_range = MemRegion(start_address, last_address + 1);
618 start_region = _hrm.addr_to_region(start_address);
619 }
620
621 // Perform the actual region allocation, exiting if it fails.
622 // Then note how much new space we have allocated.
623 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
624 return false;
625 }
626 increase_used(word_size * HeapWordSize);
627 if (commits != 0) {
628 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
629 HeapRegion::GrainWords * HeapWordSize * commits);
630
631 }
632
633 // Mark each G1 region touched by the range as archive, add it to
634 // the old set, and set top.
635 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
636 HeapRegion* last_region = _hrm.addr_to_region(last_address);
637 prev_last_region = last_region;
638
639 while (curr_region != NULL) {
640 assert(curr_region->is_empty() && !curr_region->is_pinned(),
641 "Region already in use (index %u)", curr_region->hrm_index());
642 if (open) {
643 curr_region->set_open_archive();
644 } else {
645 curr_region->set_closed_archive();
646 }
647 _hr_printer.alloc(curr_region);
648 _archive_set.add(curr_region);
649 HeapWord* top;
650 HeapRegion* next_region;
651 if (curr_region != last_region) {
652 top = curr_region->end();
653 next_region = _hrm.next_region_in_heap(curr_region);
654 } else {
655 top = last_address + 1;
656 next_region = NULL;
657 }
658 curr_region->set_top(top);
659 curr_region->set_first_dead(top);
660 curr_region->set_end_of_live(top);
661 curr_region = next_region;
662 }
663
664 // Notify mark-sweep of the archive
665 G1ArchiveAllocator::set_range_archive(curr_range, open);
666 }
667 return true;
668 }
669
670 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
671 assert(!is_init_completed(), "Expect to be called at JVM init time");
672 assert(ranges != NULL, "MemRegion array NULL");
673 assert(count != 0, "No MemRegions provided");
674 MemRegion reserved = _hrm.reserved();
675 HeapWord *prev_last_addr = NULL;
676 HeapRegion* prev_last_region = NULL;
677
678 // For each MemRegion, create filler objects, if needed, in the G1 regions
679 // that contain the address range. The address range actually within the
680 // MemRegion will not be modified. That is assumed to have been initialized
681 // elsewhere, probably via an mmap of archived heap data.
682 MutexLockerEx x(Heap_lock);
683 for (size_t i = 0; i < count; i++) {
684 HeapWord* start_address = ranges[i].start();
685 HeapWord* last_address = ranges[i].last();
686
687 assert(reserved.contains(start_address) && reserved.contains(last_address),
688 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
689 p2i(start_address), p2i(last_address));
690 assert(start_address > prev_last_addr,
691 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
692 p2i(start_address), p2i(prev_last_addr));
693
694 HeapRegion* start_region = _hrm.addr_to_region(start_address);
695 HeapRegion* last_region = _hrm.addr_to_region(last_address);
696 HeapWord* bottom_address = start_region->bottom();
697
698 // Check for a range beginning in the same region in which the
699 // previous one ended.
700 if (start_region == prev_last_region) {
701 bottom_address = prev_last_addr + 1;
702 }
703
704 // Verify that the regions were all marked as archive regions by
705 // alloc_archive_regions.
706 HeapRegion* curr_region = start_region;
707 while (curr_region != NULL) {
708 guarantee(curr_region->is_archive(),
709 "Expected archive region at index %u", curr_region->hrm_index());
710 if (curr_region != last_region) {
711 curr_region = _hrm.next_region_in_heap(curr_region);
712 } else {
713 curr_region = NULL;
714 }
715 }
716
717 prev_last_addr = last_address;
718 prev_last_region = last_region;
719
720 // Fill the memory below the allocated range with dummy object(s),
721 // if the region bottom does not match the range start, or if the previous
722 // range ended within the same G1 region, and there is a gap.
723 if (start_address != bottom_address) {
724 size_t fill_size = pointer_delta(start_address, bottom_address);
725 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
726 increase_used(fill_size * HeapWordSize);
727 }
728 }
729 }
730
731 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
732 size_t desired_word_size,
733 size_t* actual_word_size) {
734 assert_heap_not_locked_and_not_at_safepoint();
735 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
736 "be called for humongous allocation requests");
737
738 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
739
740 if (result == NULL) {
741 *actual_word_size = desired_word_size;
742 result = attempt_allocation_slow(desired_word_size);
743 }
744
745 assert_heap_not_locked();
746 if (result != NULL) {
747 assert(*actual_word_size != 0, "Actual size must have been set here");
748 dirty_young_block(result, *actual_word_size);
749 } else {
750 *actual_word_size = 0;
751 }
752
753 return result;
754 }
755
756 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count, bool is_open) {
757 assert(!is_init_completed(), "Expect to be called at JVM init time");
758 assert(ranges != NULL, "MemRegion array NULL");
759 assert(count != 0, "No MemRegions provided");
760 MemRegion reserved = _hrm.reserved();
761 HeapWord* prev_last_addr = NULL;
762 HeapRegion* prev_last_region = NULL;
763 size_t size_used = 0;
764 size_t uncommitted_regions = 0;
765
766 // For each Memregion, free the G1 regions that constitute it, and
767 // notify mark-sweep that the range is no longer to be considered 'archive.'
768 MutexLockerEx x(Heap_lock);
769 for (size_t i = 0; i < count; i++) {
770 HeapWord* start_address = ranges[i].start();
771 HeapWord* last_address = ranges[i].last();
772
773 assert(reserved.contains(start_address) && reserved.contains(last_address),
774 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
775 p2i(start_address), p2i(last_address));
776 assert(start_address > prev_last_addr,
777 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
778 p2i(start_address), p2i(prev_last_addr));
779 size_used += ranges[i].byte_size();
780 prev_last_addr = last_address;
781
782 HeapRegion* start_region = _hrm.addr_to_region(start_address);
783 HeapRegion* last_region = _hrm.addr_to_region(last_address);
784
785 // Check for ranges that start in the same G1 region in which the previous
786 // range ended, and adjust the start address so we don't try to free
787 // the same region again. If the current range is entirely within that
788 // region, skip it.
789 if (start_region == prev_last_region) {
790 start_address = start_region->end();
791 if (start_address > last_address) {
792 continue;
793 }
794 start_region = _hrm.addr_to_region(start_address);
795 }
796 prev_last_region = last_region;
797
798 // After verifying that each region was marked as an archive region by
799 // alloc_archive_regions, set it free and empty and uncommit it.
800 HeapRegion* curr_region = start_region;
801 while (curr_region != NULL) {
802 guarantee(curr_region->is_archive(),
803 "Expected archive region at index %u", curr_region->hrm_index());
804 uint curr_index = curr_region->hrm_index();
805 _archive_set.remove(curr_region);
806 curr_region->set_free();
807 curr_region->set_top(curr_region->bottom());
808 if (curr_region != last_region) {
809 curr_region = _hrm.next_region_in_heap(curr_region);
810 } else {
811 curr_region = NULL;
812 }
813 _hrm.shrink_at(curr_index, 1);
814 uncommitted_regions++;
815 }
816
817 // Notify mark-sweep that this is no longer an archive range.
818 G1ArchiveAllocator::clear_range_archive(ranges[i], is_open);
819 }
820
821 if (uncommitted_regions != 0) {
822 log_debug(gc, ergo, heap)("Attempt heap shrinking (uncommitted archive regions). Total size: " SIZE_FORMAT "B",
823 HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
824 }
825 decrease_used(size_used);
826 }
827
828 oop G1CollectedHeap::materialize_archived_object(oop obj) {
829 assert(obj != NULL, "archived obj is NULL");
830 assert(G1ArchiveAllocator::is_archived_object(obj), "must be archived object");
831
832 // Loading an archived object makes it strongly reachable. If it is
833 // loaded during concurrent marking, it must be enqueued to the SATB
834 // queue, shading the previously white object gray.
835 G1BarrierSet::enqueue(obj);
836
837 return obj;
838 }
839
840 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
841 ResourceMark rm; // For retrieving the thread names in log messages.
842
843 // The structure of this method has a lot of similarities to
844 // attempt_allocation_slow(). The reason these two were not merged
845 // into a single one is that such a method would require several "if
846 // allocation is not humongous do this, otherwise do that"
847 // conditional paths which would obscure its flow. In fact, an early
848 // version of this code did use a unified method which was harder to
849 // follow and, as a result, it had subtle bugs that were hard to
850 // track down. So keeping these two methods separate allows each to
851 // be more readable. It will be good to keep these two in sync as
852 // much as possible.
853
854 assert_heap_not_locked_and_not_at_safepoint();
855 assert(is_humongous(word_size), "attempt_allocation_humongous() "
856 "should only be called for humongous allocations");
857
858 // Humongous objects can exhaust the heap quickly, so we should check if we
859 // need to start a marking cycle at each humongous object allocation. We do
860 // the check before we do the actual allocation. The reason for doing it
861 // before the allocation is that we avoid having to keep track of the newly
862 // allocated memory while we do a GC.
863 if (g1_policy()->need_to_start_conc_mark("concurrent humongous allocation",
864 word_size)) {
865 collect(GCCause::_g1_humongous_allocation);
866 }
867
868 // We will loop until a) we manage to successfully perform the
869 // allocation or b) we successfully schedule a collection which
870 // fails to perform the allocation. b) is the only case when we'll
871 // return NULL.
872 HeapWord* result = NULL;
873 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
874 bool should_try_gc;
875 uint gc_count_before;
876
877
878 {
879 MutexLockerEx x(Heap_lock);
880
881 // Given that humongous objects are not allocated in young
882 // regions, we'll first try to do the allocation without doing a
883 // collection hoping that there's enough space in the heap.
884 result = humongous_obj_allocate(word_size);
885 if (result != NULL) {
886 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
887 g1_policy()->add_bytes_allocated_in_old_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
888 return result;
889 }
890
891 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
892 // the GCLocker initiated GC has been performed and then retry. This includes
893 // the case when the GC Locker is not active but has not been performed.
894 should_try_gc = !GCLocker::needs_gc();
895 // Read the GC count while still holding the Heap_lock.
896 gc_count_before = total_collections();
897 }
898
899 if (should_try_gc) {
900 bool succeeded;
901 result = do_collection_pause(word_size, gc_count_before, &succeeded,
902 GCCause::_g1_humongous_allocation);
903 if (result != NULL) {
904 assert(succeeded, "only way to get back a non-NULL result");
905 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
906 Thread::current()->name(), p2i(result));
907 return result;
908 }
909
910 if (succeeded) {
911 // We successfully scheduled a collection which failed to allocate. No
912 // point in trying to allocate further. We'll just return NULL.
913 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
914 SIZE_FORMAT " words", Thread::current()->name(), word_size);
915 return NULL;
916 }
917 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
918 Thread::current()->name(), word_size);
919 } else {
920 // Failed to schedule a collection.
921 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
922 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
923 SIZE_FORMAT " words", Thread::current()->name(), word_size);
924 return NULL;
925 }
926 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
927 // The GCLocker is either active or the GCLocker initiated
928 // GC has not yet been performed. Stall until it is and
929 // then retry the allocation.
930 GCLocker::stall_until_clear();
931 gclocker_retry_count += 1;
932 }
933
934
935 // We can reach here if we were unsuccessful in scheduling a
936 // collection (because another thread beat us to it) or if we were
937 // stalled due to the GC locker. In either can we should retry the
938 // allocation attempt in case another thread successfully
939 // performed a collection and reclaimed enough space.
940 // Humongous object allocation always needs a lock, so we wait for the retry
941 // in the next iteration of the loop, unlike for the regular iteration case.
942 // Give a warning if we seem to be looping forever.
943
944 if ((QueuedAllocationWarningCount > 0) &&
945 (try_count % QueuedAllocationWarningCount == 0)) {
946 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
947 Thread::current()->name(), try_count, word_size);
948 }
949 }
950
951 ShouldNotReachHere();
952 return NULL;
953 }
954
955 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
956 bool expect_null_mutator_alloc_region) {
957 assert_at_safepoint_on_vm_thread();
958 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
959 "the current alloc region was unexpectedly found to be non-NULL");
960
961 if (!is_humongous(word_size)) {
962 return _allocator->attempt_allocation_locked(word_size);
963 } else {
964 HeapWord* result = humongous_obj_allocate(word_size);
965 if (result != NULL && g1_policy()->need_to_start_conc_mark("STW humongous allocation")) {
966 collector_state()->set_initiate_conc_mark_if_possible(true);
967 }
968 return result;
969 }
970
971 ShouldNotReachHere();
972 }
973
974 class PostCompactionPrinterClosure: public HeapRegionClosure {
975 private:
976 G1HRPrinter* _hr_printer;
977 public:
978 bool do_heap_region(HeapRegion* hr) {
979 assert(!hr->is_young(), "not expecting to find young regions");
980 _hr_printer->post_compaction(hr);
981 return false;
982 }
983
984 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
985 : _hr_printer(hr_printer) { }
986 };
987
988 void G1CollectedHeap::print_hrm_post_compaction() {
989 if (_hr_printer.is_active()) {
990 PostCompactionPrinterClosure cl(hr_printer());
991 heap_region_iterate(&cl);
992 }
993 }
994
995 void G1CollectedHeap::abort_concurrent_cycle() {
996 // If we start the compaction before the CM threads finish
997 // scanning the root regions we might trip them over as we'll
998 // be moving objects / updating references. So let's wait until
999 // they are done. By telling them to abort, they should complete
1000 // early.
1001 _cm->root_regions()->abort();
1002 _cm->root_regions()->wait_until_scan_finished();
1003
1004 // Disable discovery and empty the discovered lists
1005 // for the CM ref processor.
1006 _ref_processor_cm->disable_discovery();
1007 _ref_processor_cm->abandon_partial_discovery();
1008 _ref_processor_cm->verify_no_references_recorded();
1009
1010 // Abandon current iterations of concurrent marking and concurrent
1011 // refinement, if any are in progress.
1012 concurrent_mark()->concurrent_cycle_abort();
1013 }
1014
1015 void G1CollectedHeap::prepare_heap_for_full_collection() {
1016 // Make sure we'll choose a new allocation region afterwards.
1017 _allocator->release_mutator_alloc_region();
1018 _allocator->abandon_gc_alloc_regions();
1019
1020 // We may have added regions to the current incremental collection
1021 // set between the last GC or pause and now. We need to clear the
1022 // incremental collection set and then start rebuilding it afresh
1023 // after this full GC.
1024 abandon_collection_set(collection_set());
1025
1026 tear_down_region_sets(false /* free_list_only */);
1027 }
1028
1029 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1030 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1031 assert(used() == recalculate_used(), "Should be equal");
1032 _verifier->verify_region_sets_optional();
1033 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1034 _verifier->check_bitmaps("Full GC Start");
1035 }
1036
1037 void G1CollectedHeap::prepare_heap_for_mutators() {
1038 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1039 ClassLoaderDataGraph::purge();
1040 MetaspaceUtils::verify_metrics();
1041
1042 // Prepare heap for normal collections.
1043 assert(num_free_regions() == 0, "we should not have added any free regions");
1044 rebuild_region_sets(false /* free_list_only */);
1045 abort_refinement();
1046 resize_heap_if_necessary();
1047
1048 // Rebuild the strong code root lists for each region
1049 rebuild_strong_code_roots();
1050
1051 // Purge code root memory
1052 purge_code_root_memory();
1053
1054 // Start a new incremental collection set for the next pause
1055 start_new_collection_set();
1056
1057 _allocator->init_mutator_alloc_region();
1058
1059 // Post collection state updates.
1060 MetaspaceGC::compute_new_size();
1061 }
1062
1063 void G1CollectedHeap::abort_refinement() {
1064 if (_hot_card_cache->use_cache()) {
1065 _hot_card_cache->reset_hot_cache();
1066 }
1067
1068 // Discard all remembered set updates.
1069 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1070 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1071 }
1072
1073 void G1CollectedHeap::verify_after_full_collection() {
1074 _hrm.verify_optional();
1075 _verifier->verify_region_sets_optional();
1076 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1077 // Clear the previous marking bitmap, if needed for bitmap verification.
1078 // Note we cannot do this when we clear the next marking bitmap in
1079 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1080 // objects marked during a full GC against the previous bitmap.
1081 // But we need to clear it before calling check_bitmaps below since
1082 // the full GC has compacted objects and updated TAMS but not updated
1083 // the prev bitmap.
1084 if (G1VerifyBitmaps) {
1085 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1086 _cm->clear_prev_bitmap(workers());
1087 }
1088 // This call implicitly verifies that the next bitmap is clear after Full GC.
1089 _verifier->check_bitmaps("Full GC End");
1090
1091 // At this point there should be no regions in the
1092 // entire heap tagged as young.
1093 assert(check_young_list_empty(), "young list should be empty at this point");
1094
1095 // Note: since we've just done a full GC, concurrent
1096 // marking is no longer active. Therefore we need not
1097 // re-enable reference discovery for the CM ref processor.
1098 // That will be done at the start of the next marking cycle.
1099 // We also know that the STW processor should no longer
1100 // discover any new references.
1101 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1102 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1103 _ref_processor_stw->verify_no_references_recorded();
1104 _ref_processor_cm->verify_no_references_recorded();
1105 }
1106
1107 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1108 // Post collection logging.
1109 // We should do this after we potentially resize the heap so
1110 // that all the COMMIT / UNCOMMIT events are generated before
1111 // the compaction events.
1112 print_hrm_post_compaction();
1113 heap_transition->print();
1114 print_heap_after_gc();
1115 print_heap_regions();
1116 #ifdef TRACESPINNING
1117 ParallelTaskTerminator::print_termination_counts();
1118 #endif
1119 }
1120
1121 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1122 bool clear_all_soft_refs) {
1123 assert_at_safepoint_on_vm_thread();
1124
1125 if (GCLocker::check_active_before_gc()) {
1126 // Full GC was not completed.
1127 return false;
1128 }
1129
1130 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1131 soft_ref_policy()->should_clear_all_soft_refs();
1132
1133 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1134 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1135
1136 collector.prepare_collection();
1137 collector.collect();
1138 collector.complete_collection();
1139
1140 // Full collection was successfully completed.
1141 return true;
1142 }
1143
1144 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1145 // Currently, there is no facility in the do_full_collection(bool) API to notify
1146 // the caller that the collection did not succeed (e.g., because it was locked
1147 // out by the GC locker). So, right now, we'll ignore the return value.
1148 bool dummy = do_full_collection(true, /* explicit_gc */
1149 clear_all_soft_refs);
1150 }
1151
1152 void G1CollectedHeap::resize_heap_if_necessary() {
1153 // Capacity, free and used after the GC counted as full regions to
1154 // include the waste in the following calculations.
1155 const size_t capacity_after_gc = capacity();
1156 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1157
1158 // This is enforced in arguments.cpp.
1159 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1160 "otherwise the code below doesn't make sense");
1161
1162 // We don't have floating point command-line arguments
1163 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1164 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1165 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1166 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1167
1168 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1169 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1170
1171 // We have to be careful here as these two calculations can overflow
1172 // 32-bit size_t's.
1173 double used_after_gc_d = (double) used_after_gc;
1174 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1175 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1176
1177 // Let's make sure that they are both under the max heap size, which
1178 // by default will make them fit into a size_t.
1179 double desired_capacity_upper_bound = (double) max_heap_size;
1180 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1181 desired_capacity_upper_bound);
1182 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1183 desired_capacity_upper_bound);
1184
1185 // We can now safely turn them into size_t's.
1186 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1187 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1188
1189 // This assert only makes sense here, before we adjust them
1190 // with respect to the min and max heap size.
1191 assert(minimum_desired_capacity <= maximum_desired_capacity,
1192 "minimum_desired_capacity = " SIZE_FORMAT ", "
1193 "maximum_desired_capacity = " SIZE_FORMAT,
1194 minimum_desired_capacity, maximum_desired_capacity);
1195
1196 // Should not be greater than the heap max size. No need to adjust
1197 // it with respect to the heap min size as it's a lower bound (i.e.,
1198 // we'll try to make the capacity larger than it, not smaller).
1199 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1200 // Should not be less than the heap min size. No need to adjust it
1201 // with respect to the heap max size as it's an upper bound (i.e.,
1202 // we'll try to make the capacity smaller than it, not greater).
1203 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1204
1205 if (capacity_after_gc < minimum_desired_capacity) {
1206 // Don't expand unless it's significant
1207 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1208
1209 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity). "
1210 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1211 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1212 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1213
1214 expand(expand_bytes, _workers);
1215
1216 // No expansion, now see if we want to shrink
1217 } else if (capacity_after_gc > maximum_desired_capacity) {
1218 // Capacity too large, compute shrinking size
1219 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1220
1221 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity). "
1222 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1223 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1224 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1225
1226 shrink(shrink_bytes);
1227 }
1228 }
1229
1230 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1231 bool do_gc,
1232 bool clear_all_soft_refs,
1233 bool expect_null_mutator_alloc_region,
1234 bool* gc_succeeded) {
1235 *gc_succeeded = true;
1236 // Let's attempt the allocation first.
1237 HeapWord* result =
1238 attempt_allocation_at_safepoint(word_size,
1239 expect_null_mutator_alloc_region);
1240 if (result != NULL) {
1241 return result;
1242 }
1243
1244 // In a G1 heap, we're supposed to keep allocation from failing by
1245 // incremental pauses. Therefore, at least for now, we'll favor
1246 // expansion over collection. (This might change in the future if we can
1247 // do something smarter than full collection to satisfy a failed alloc.)
1248 result = expand_and_allocate(word_size);
1249 if (result != NULL) {
1250 return result;
1251 }
1252
1253 if (do_gc) {
1254 // Expansion didn't work, we'll try to do a Full GC.
1255 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1256 clear_all_soft_refs);
1257 }
1258
1259 return NULL;
1260 }
1261
1262 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1263 bool* succeeded) {
1264 assert_at_safepoint_on_vm_thread();
1265
1266 // Attempts to allocate followed by Full GC.
1267 HeapWord* result =
1268 satisfy_failed_allocation_helper(word_size,
1269 true, /* do_gc */
1270 false, /* clear_all_soft_refs */
1271 false, /* expect_null_mutator_alloc_region */
1272 succeeded);
1273
1274 if (result != NULL || !*succeeded) {
1275 return result;
1276 }
1277
1278 // Attempts to allocate followed by Full GC that will collect all soft references.
1279 result = satisfy_failed_allocation_helper(word_size,
1280 true, /* do_gc */
1281 true, /* clear_all_soft_refs */
1282 true, /* expect_null_mutator_alloc_region */
1283 succeeded);
1284
1285 if (result != NULL || !*succeeded) {
1286 return result;
1287 }
1288
1289 // Attempts to allocate, no GC
1290 result = satisfy_failed_allocation_helper(word_size,
1291 false, /* do_gc */
1292 false, /* clear_all_soft_refs */
1293 true, /* expect_null_mutator_alloc_region */
1294 succeeded);
1295
1296 if (result != NULL) {
1297 return result;
1298 }
1299
1300 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1301 "Flag should have been handled and cleared prior to this point");
1302
1303 // What else? We might try synchronous finalization later. If the total
1304 // space available is large enough for the allocation, then a more
1305 // complete compaction phase than we've tried so far might be
1306 // appropriate.
1307 return NULL;
1308 }
1309
1310 // Attempting to expand the heap sufficiently
1311 // to support an allocation of the given "word_size". If
1312 // successful, perform the allocation and return the address of the
1313 // allocated block, or else "NULL".
1314
1315 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1316 assert_at_safepoint_on_vm_thread();
1317
1318 _verifier->verify_region_sets_optional();
1319
1320 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1321 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1322 word_size * HeapWordSize);
1323
1324
1325 if (expand(expand_bytes, _workers)) {
1326 _hrm.verify_optional();
1327 _verifier->verify_region_sets_optional();
1328 return attempt_allocation_at_safepoint(word_size,
1329 false /* expect_null_mutator_alloc_region */);
1330 }
1331 return NULL;
1332 }
1333
1334 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1335 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1336 aligned_expand_bytes = align_up(aligned_expand_bytes,
1337 HeapRegion::GrainBytes);
1338
1339 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1340 expand_bytes, aligned_expand_bytes);
1341
1342 if (is_maximal_no_gc()) {
1343 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1344 return false;
1345 }
1346
1347 double expand_heap_start_time_sec = os::elapsedTime();
1348 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1349 assert(regions_to_expand > 0, "Must expand by at least one region");
1350
1351 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1352 if (expand_time_ms != NULL) {
1353 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1354 }
1355
1356 if (expanded_by > 0) {
1357 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1358 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1359 g1_policy()->record_new_heap_size(num_regions());
1360 } else {
1361 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1362
1363 // The expansion of the virtual storage space was unsuccessful.
1364 // Let's see if it was because we ran out of swap.
1365 if (G1ExitOnExpansionFailure &&
1366 _hrm.available() >= regions_to_expand) {
1367 // We had head room...
1368 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1369 }
1370 }
1371 return regions_to_expand > 0;
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
1385 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",
1386 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1387 if (num_regions_removed > 0) {
1388 g1_policy()->record_new_heap_size(num_regions());
1389 } else {
1390 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1391 }
1392 }
1393
1394 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1395 _verifier->verify_region_sets_optional();
1396
1397 // We should only reach here at the end of a Full GC or during Remark which
1398 // means we should not not be holding to any GC alloc regions. The method
1399 // below will make sure of that and do any remaining clean up.
1400 _allocator->abandon_gc_alloc_regions();
1401
1402 // Instead of tearing down / rebuilding the free lists here, we
1403 // could instead use the remove_all_pending() method on free_list to
1404 // remove only the ones that we need to remove.
1405 tear_down_region_sets(true /* free_list_only */);
1406 shrink_helper(shrink_bytes);
1407 rebuild_region_sets(true /* free_list_only */);
1408
1409 _hrm.verify_optional();
1410 _verifier->verify_region_sets_optional();
1411 }
1412
1413 class OldRegionSetChecker : public HeapRegionSetChecker {
1414 public:
1415 void check_mt_safety() {
1416 // Master Old Set MT safety protocol:
1417 // (a) If we're at a safepoint, operations on the master old set
1418 // should be invoked:
1419 // - by the VM thread (which will serialize them), or
1420 // - by the GC workers while holding the FreeList_lock, if we're
1421 // at a safepoint for an evacuation pause (this lock is taken
1422 // anyway when an GC alloc region is retired so that a new one
1423 // is allocated from the free list), or
1424 // - by the GC workers while holding the OldSets_lock, if we're at a
1425 // safepoint for a cleanup pause.
1426 // (b) If we're not at a safepoint, operations on the master old set
1427 // should be invoked while holding the Heap_lock.
1428
1429 if (SafepointSynchronize::is_at_safepoint()) {
1430 guarantee(Thread::current()->is_VM_thread() ||
1431 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1432 "master old set MT safety protocol at a safepoint");
1433 } else {
1434 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1435 }
1436 }
1437 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1438 const char* get_description() { return "Old Regions"; }
1439 };
1440
1441 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1442 public:
1443 void check_mt_safety() {
1444 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1445 "May only change archive regions during initialization or safepoint.");
1446 }
1447 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1448 const char* get_description() { return "Archive Regions"; }
1449 };
1450
1451 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1452 public:
1453 void check_mt_safety() {
1454 // Humongous Set MT safety protocol:
1455 // (a) If we're at a safepoint, operations on the master humongous
1456 // set should be invoked by either the VM thread (which will
1457 // serialize them) or by the GC workers while holding the
1458 // OldSets_lock.
1459 // (b) If we're not at a safepoint, operations on the master
1460 // humongous set should be invoked while holding the Heap_lock.
1461
1462 if (SafepointSynchronize::is_at_safepoint()) {
1463 guarantee(Thread::current()->is_VM_thread() ||
1464 OldSets_lock->owned_by_self(),
1465 "master humongous set MT safety protocol at a safepoint");
1466 } else {
1467 guarantee(Heap_lock->owned_by_self(),
1468 "master humongous set MT safety protocol outside a safepoint");
1469 }
1470 }
1471 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1472 const char* get_description() { return "Humongous Regions"; }
1473 };
1474
1475 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1476 CollectedHeap(),
1477 _young_gen_sampling_thread(NULL),
1478 _workers(NULL),
1479 _collector_policy(collector_policy),
1480 _card_table(NULL),
1481 _soft_ref_policy(),
1482 _old_set("Old Region Set", new OldRegionSetChecker()),
1483 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1484 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1485 _bot(NULL),
1486 _listener(),
1487 _hrm(),
1488 _allocator(NULL),
1489 _verifier(NULL),
1490 _summary_bytes_used(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 _g1_policy(new G1Policy(_gc_timer_stw)),
1507 _heap_sizing_policy(NULL),
1508 _collection_set(this, _g1_policy),
1509 _hot_card_cache(NULL),
1510 _g1_rem_set(NULL),
1511 _dirty_card_queue_set(false),
1512 _cm(NULL),
1513 _cm_thread(NULL),
1514 _cr(NULL),
1515 _task_queues(NULL),
1516 _evacuation_failed(false),
1517 _evacuation_failed_info_array(NULL),
1518 _preserved_marks_set(true /* in_c_heap */),
1519 #ifndef PRODUCT
1520 _evacuation_failure_alot_for_current_gc(false),
1521 _evacuation_failure_alot_gc_number(0),
1522 _evacuation_failure_alot_count(0),
1523 #endif
1524 _ref_processor_stw(NULL),
1525 _is_alive_closure_stw(this),
1526 _is_subject_to_discovery_stw(this),
1527 _ref_processor_cm(NULL),
1528 _is_alive_closure_cm(this),
1529 _is_subject_to_discovery_cm(this),
1530 _in_cset_fast_test() {
1531
1532 _verifier = new G1HeapVerifier(this);
1533
1534 _allocator = new G1Allocator(this);
1535
1536 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1537
1538 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1539
1540 // Override the default _filler_array_max_size so that no humongous filler
1541 // objects are created.
1542 _filler_array_max_size = _humongous_object_threshold_in_words;
1543
1544 uint n_queues = ParallelGCThreads;
1545 _task_queues = new RefToScanQueueSet(n_queues);
1546
1547 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1548
1549 for (uint i = 0; i < n_queues; i++) {
1550 RefToScanQueue* q = new RefToScanQueue();
1551 q->initialize();
1552 _task_queues->register_queue(i, q);
1553 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1554 }
1555
1556 // Initialize the G1EvacuationFailureALot counters and flags.
1557 NOT_PRODUCT(reset_evacuation_should_fail();)
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 page_size = rs.alignment();
1572 }
1573 }
1574
1575 return page_size;
1576 }
1577
1578 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1579 size_t size,
1580 size_t translation_factor) {
1581 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1582 // Allocate a new reserved space, preferring to use large pages.
1583 ReservedSpace rs(size, preferred_page_size);
1584 size_t page_size = actual_reserved_page_size(rs);
1585 G1RegionToSpaceMapper* result =
1586 G1RegionToSpaceMapper::create_mapper(rs,
1587 size,
1588 page_size,
1589 HeapRegion::GrainBytes,
1590 translation_factor,
1591 mtGC);
1592
1593 os::trace_page_sizes_for_requested_size(description,
1594 size,
1595 preferred_page_size,
1596 page_size,
1597 rs.base(),
1598 rs.size());
1599
1600 return result;
1601 }
1602
1603 jint G1CollectedHeap::initialize_concurrent_refinement() {
1604 jint ecode = JNI_OK;
1605 _cr = G1ConcurrentRefine::create(&ecode);
1606 return ecode;
1607 }
1608
1609 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1610 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1611 if (_young_gen_sampling_thread->osthread() == NULL) {
1612 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1613 return JNI_ENOMEM;
1614 }
1615 return JNI_OK;
1616 }
1617
1618 jint G1CollectedHeap::initialize() {
1619 os::enable_vtime();
1620
1621 // Necessary to satisfy locking discipline assertions.
1622
1623 MutexLocker x(Heap_lock);
1624
1625 // While there are no constraints in the GC code that HeapWordSize
1626 // be any particular value, there are multiple other areas in the
1627 // system which believe this to be true (e.g. oop->object_size in some
1628 // cases incorrectly returns the size in wordSize units rather than
1629 // HeapWordSize).
1630 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1631
1632 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1633 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1634 size_t heap_alignment = collector_policy()->heap_alignment();
1635
1636 // Ensure that the sizes are properly aligned.
1637 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1638 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1639 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1640
1641 // Reserve the maximum.
1642
1643 // When compressed oops are enabled, the preferred heap base
1644 // is calculated by subtracting the requested size from the
1645 // 32Gb boundary and using the result as the base address for
1646 // heap reservation. If the requested size is not aligned to
1647 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1648 // into the ReservedHeapSpace constructor) then the actual
1649 // base of the reserved heap may end up differing from the
1650 // address that was requested (i.e. the preferred heap base).
1651 // If this happens then we could end up using a non-optimal
1652 // compressed oops mode.
1653
1654 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1655 heap_alignment);
1656
1657 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1658
1659 // Create the barrier set for the entire reserved region.
1660 G1CardTable* ct = new G1CardTable(reserved_region());
1661 ct->initialize();
1662 G1BarrierSet* bs = new G1BarrierSet(ct);
1663 bs->initialize();
1664 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1665 BarrierSet::set_barrier_set(bs);
1666 _card_table = ct;
1667
1668 G1BarrierSet::satb_mark_queue_set().initialize(this,
1669 SATB_Q_CBL_mon,
1670 &bs->satb_mark_queue_buffer_allocator(),
1671 G1SATBProcessCompletedThreshold,
1672 G1SATBBufferEnqueueingThresholdPercent,
1673 Shared_SATB_Q_lock);
1674
1675 // process_completed_buffers_threshold and max_completed_buffers are updated
1676 // later, based on the concurrent refinement object.
1677 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1678 &bs->dirty_card_queue_buffer_allocator(),
1679 Shared_DirtyCardQ_lock,
1680 true); // init_free_ids
1681
1682 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1683 &bs->dirty_card_queue_buffer_allocator(),
1684 Shared_DirtyCardQ_lock);
1685
1686 // Create the hot card cache.
1687 _hot_card_cache = new G1HotCardCache(this);
1688
1689 // Carve out the G1 part of the heap.
1690 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1691 size_t page_size = actual_reserved_page_size(heap_rs);
1692 G1RegionToSpaceMapper* heap_storage =
1693 G1RegionToSpaceMapper::create_mapper(g1_rs,
1694 g1_rs.size(),
1695 page_size,
1696 HeapRegion::GrainBytes,
1697 1,
1698 mtJavaHeap);
1699 os::trace_page_sizes("Heap",
1700 collector_policy()->min_heap_byte_size(),
1701 max_byte_size,
1702 page_size,
1703 heap_rs.base(),
1704 heap_rs.size());
1705 heap_storage->set_mapping_changed_listener(&_listener);
1706
1707 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1708 G1RegionToSpaceMapper* bot_storage =
1709 create_aux_memory_mapper("Block Offset Table",
1710 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1711 G1BlockOffsetTable::heap_map_factor());
1712
1713 G1RegionToSpaceMapper* cardtable_storage =
1714 create_aux_memory_mapper("Card Table",
1715 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1716 G1CardTable::heap_map_factor());
1717
1718 G1RegionToSpaceMapper* card_counts_storage =
1719 create_aux_memory_mapper("Card Counts Table",
1720 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1721 G1CardCounts::heap_map_factor());
1722
1723 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1724 G1RegionToSpaceMapper* prev_bitmap_storage =
1725 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1726 G1RegionToSpaceMapper* next_bitmap_storage =
1727 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1728
1729 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1730 _card_table->initialize(cardtable_storage);
1731 // Do later initialization work for concurrent refinement.
1732 _hot_card_cache->initialize(card_counts_storage);
1733
1734 // 6843694 - ensure that the maximum region index can fit
1735 // in the remembered set structures.
1736 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1737 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1738
1739 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1740 // start within the first card.
1741 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1742 // Also create a G1 rem set.
1743 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1744 _g1_rem_set->initialize(max_capacity(), max_regions());
1745
1746 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1747 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1748 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1749 "too many cards per region");
1750
1751 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1752
1753 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1754
1755 {
1756 HeapWord* start = _hrm.reserved().start();
1757 HeapWord* end = _hrm.reserved().end();
1758 size_t granularity = HeapRegion::GrainBytes;
1759
1760 _in_cset_fast_test.initialize(start, end, granularity);
1761 _humongous_reclaim_candidates.initialize(start, end, granularity);
1762 }
1763
1764 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1765 true /* are_GC_task_threads */,
1766 false /* are_ConcurrentGC_threads */);
1767 if (_workers == NULL) {
1768 return JNI_ENOMEM;
1769 }
1770 _workers->initialize_workers();
1771
1772 // Create the G1ConcurrentMark data structure and thread.
1773 // (Must do this late, so that "max_regions" is defined.)
1774 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1775 if (_cm == NULL || !_cm->completed_initialization()) {
1776 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1777 return JNI_ENOMEM;
1778 }
1779 _cm_thread = _cm->cm_thread();
1780
1781 // Now expand into the initial heap size.
1782 if (!expand(init_byte_size, _workers)) {
1783 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1784 return JNI_ENOMEM;
1785 }
1786
1787 // Perform any initialization actions delegated to the policy.
1788 g1_policy()->init(this, &_collection_set);
1789
1790 jint ecode = initialize_concurrent_refinement();
1791 if (ecode != JNI_OK) {
1792 return ecode;
1793 }
1794
1795 ecode = initialize_young_gen_sampling_thread();
1796 if (ecode != JNI_OK) {
1797 return ecode;
1798 }
1799
1800 {
1801 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1802 dcqs.set_process_completed_buffers_threshold(concurrent_refine()->yellow_zone());
1803 dcqs.set_max_completed_buffers(concurrent_refine()->red_zone());
1804 }
1805
1806 // Here we allocate the dummy HeapRegion that is required by the
1807 // G1AllocRegion class.
1808 HeapRegion* dummy_region = _hrm.get_dummy_region();
1809
1810 // We'll re-use the same region whether the alloc region will
1811 // require BOT updates or not and, if it doesn't, then a non-young
1812 // region will complain that it cannot support allocations without
1813 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1814 dummy_region->set_eden();
1815 // Make sure it's full.
1816 dummy_region->set_top(dummy_region->end());
1817 G1AllocRegion::setup(this, dummy_region);
1818
1819 _allocator->init_mutator_alloc_region();
1820
1821 // Do create of the monitoring and management support so that
1822 // values in the heap have been properly initialized.
1823 _g1mm = new G1MonitoringSupport(this);
1824
1825 G1StringDedup::initialize();
1826
1827 _preserved_marks_set.init(ParallelGCThreads);
1828
1829 _collection_set.initialize(max_regions());
1830
1831 return JNI_OK;
1832 }
1833
1834 void G1CollectedHeap::stop() {
1835 // Stop all concurrent threads. We do this to make sure these threads
1836 // do not continue to execute and access resources (e.g. logging)
1837 // that are destroyed during shutdown.
1838 _cr->stop();
1839 _young_gen_sampling_thread->stop();
1840 _cm_thread->stop();
1841 if (G1StringDedup::is_enabled()) {
1842 G1StringDedup::stop();
1843 }
1844 }
1845
1846 void G1CollectedHeap::safepoint_synchronize_begin() {
1847 SuspendibleThreadSet::synchronize();
1848 }
1849
1850 void G1CollectedHeap::safepoint_synchronize_end() {
1851 SuspendibleThreadSet::desynchronize();
1852 }
1853
1854 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1855 return HeapRegion::max_region_size();
1856 }
1857
1858 void G1CollectedHeap::post_initialize() {
1859 CollectedHeap::post_initialize();
1860 ref_processing_init();
1861 }
1862
1863 void G1CollectedHeap::ref_processing_init() {
1864 // Reference processing in G1 currently works as follows:
1865 //
1866 // * There are two reference processor instances. One is
1867 // used to record and process discovered references
1868 // during concurrent marking; the other is used to
1869 // record and process references during STW pauses
1870 // (both full and incremental).
1871 // * Both ref processors need to 'span' the entire heap as
1872 // the regions in the collection set may be dotted around.
1873 //
1874 // * For the concurrent marking ref processor:
1875 // * Reference discovery is enabled at initial marking.
1876 // * Reference discovery is disabled and the discovered
1877 // references processed etc during remarking.
1878 // * Reference discovery is MT (see below).
1879 // * Reference discovery requires a barrier (see below).
1880 // * Reference processing may or may not be MT
1881 // (depending on the value of ParallelRefProcEnabled
1882 // and ParallelGCThreads).
1883 // * A full GC disables reference discovery by the CM
1884 // ref processor and abandons any entries on it's
1885 // discovered lists.
1886 //
1887 // * For the STW processor:
1888 // * Non MT discovery is enabled at the start of a full GC.
1889 // * Processing and enqueueing during a full GC is non-MT.
1890 // * During a full GC, references are processed after marking.
1891 //
1892 // * Discovery (may or may not be MT) is enabled at the start
1893 // of an incremental evacuation pause.
1894 // * References are processed near the end of a STW evacuation pause.
1895 // * For both types of GC:
1896 // * Discovery is atomic - i.e. not concurrent.
1897 // * Reference discovery will not need a barrier.
1898
1899 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1900
1901 // Concurrent Mark ref processor
1902 _ref_processor_cm =
1903 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1904 mt_processing, // mt processing
1905 ParallelGCThreads, // degree of mt processing
1906 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1907 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1908 false, // Reference discovery is not atomic
1909 &_is_alive_closure_cm, // is alive closure
1910 true); // allow changes to number of processing threads
1911
1912 // STW ref processor
1913 _ref_processor_stw =
1914 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1915 mt_processing, // mt processing
1916 ParallelGCThreads, // degree of mt processing
1917 (ParallelGCThreads > 1), // mt discovery
1918 ParallelGCThreads, // degree of mt discovery
1919 true, // Reference discovery is atomic
1920 &_is_alive_closure_stw, // is alive closure
1921 true); // allow changes to number of processing threads
1922 }
1923
1924 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1925 return _collector_policy;
1926 }
1927
1928 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1929 return &_soft_ref_policy;
1930 }
1931
1932 size_t G1CollectedHeap::capacity() const {
1933 return _hrm.length() * HeapRegion::GrainBytes;
1934 }
1935
1936 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1937 return _hrm.total_free_bytes();
1938 }
1939
1940 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1941 _hot_card_cache->drain(cl, worker_i);
1942 }
1943
1944 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1945 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1946 size_t n_completed_buffers = 0;
1947 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1948 n_completed_buffers++;
1949 }
1950 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1951 dcqs.clear_n_completed_buffers();
1952 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1953 }
1954
1955 // Computes the sum of the storage used by the various regions.
1956 size_t G1CollectedHeap::used() const {
1957 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1958 if (_archive_allocator != NULL) {
1959 result += _archive_allocator->used();
1960 }
1961 return result;
1962 }
1963
1964 size_t G1CollectedHeap::used_unlocked() const {
1965 return _summary_bytes_used;
1966 }
1967
1968 class SumUsedClosure: public HeapRegionClosure {
1969 size_t _used;
1970 public:
1971 SumUsedClosure() : _used(0) {}
1972 bool do_heap_region(HeapRegion* r) {
1973 _used += r->used();
1974 return false;
1975 }
1976 size_t result() { return _used; }
1977 };
1978
1979 size_t G1CollectedHeap::recalculate_used() const {
1980 SumUsedClosure blk;
1981 heap_region_iterate(&blk);
1982 return blk.result();
1983 }
1984
1985 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1986 switch (cause) {
1987 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1988 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1989 case GCCause::_wb_conc_mark: return true;
1990 default : return false;
1991 }
1992 }
1993
1994 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1995 switch (cause) {
1996 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1997 case GCCause::_g1_humongous_allocation: return true;
1998 default: return is_user_requested_concurrent_full_gc(cause);
1999 }
2000 }
2001
2002 #ifndef PRODUCT
2003 void G1CollectedHeap::allocate_dummy_regions() {
2004 // Let's fill up most of the region
2005 size_t word_size = HeapRegion::GrainWords - 1024;
2006 // And as a result the region we'll allocate will be humongous.
2007 guarantee(is_humongous(word_size), "sanity");
2008
2009 // _filler_array_max_size is set to humongous object threshold
2010 // but temporarily change it to use CollectedHeap::fill_with_object().
2011 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2012
2013 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2014 // Let's use the existing mechanism for the allocation
2015 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2016 if (dummy_obj != NULL) {
2017 MemRegion mr(dummy_obj, word_size);
2018 CollectedHeap::fill_with_object(mr);
2019 } else {
2020 // If we can't allocate once, we probably cannot allocate
2021 // again. Let's get out of the loop.
2022 break;
2023 }
2024 }
2025 }
2026 #endif // !PRODUCT
2027
2028 void G1CollectedHeap::increment_old_marking_cycles_started() {
2029 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2030 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2031 "Wrong marking cycle count (started: %d, completed: %d)",
2032 _old_marking_cycles_started, _old_marking_cycles_completed);
2033
2034 _old_marking_cycles_started++;
2035 }
2036
2037 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2038 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2039
2040 // We assume that if concurrent == true, then the caller is a
2041 // concurrent thread that was joined the Suspendible Thread
2042 // Set. If there's ever a cheap way to check this, we should add an
2043 // assert here.
2044
2045 // Given that this method is called at the end of a Full GC or of a
2046 // concurrent cycle, and those can be nested (i.e., a Full GC can
2047 // interrupt a concurrent cycle), the number of full collections
2048 // completed should be either one (in the case where there was no
2049 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2050 // behind the number of full collections started.
2051
2052 // This is the case for the inner caller, i.e. a Full GC.
2053 assert(concurrent ||
2054 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2055 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2056 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2057 "is inconsistent with _old_marking_cycles_completed = %u",
2058 _old_marking_cycles_started, _old_marking_cycles_completed);
2059
2060 // This is the case for the outer caller, i.e. the concurrent cycle.
2061 assert(!concurrent ||
2062 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2063 "for outer caller (concurrent cycle): "
2064 "_old_marking_cycles_started = %u "
2065 "is inconsistent with _old_marking_cycles_completed = %u",
2066 _old_marking_cycles_started, _old_marking_cycles_completed);
2067
2068 _old_marking_cycles_completed += 1;
2069
2070 // We need to clear the "in_progress" flag in the CM thread before
2071 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2072 // is set) so that if a waiter requests another System.gc() it doesn't
2073 // incorrectly see that a marking cycle is still in progress.
2074 if (concurrent) {
2075 _cm_thread->set_idle();
2076 }
2077
2078 // This notify_all() will ensure that a thread that called
2079 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2080 // and it's waiting for a full GC to finish will be woken up. It is
2081 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2082 FullGCCount_lock->notify_all();
2083 }
2084
2085 void G1CollectedHeap::collect(GCCause::Cause cause) {
2086 assert_heap_not_locked();
2087
2088 uint gc_count_before;
2089 uint old_marking_count_before;
2090 uint full_gc_count_before;
2091 bool retry_gc;
2092
2093 do {
2094 retry_gc = false;
2095
2096 {
2097 MutexLocker ml(Heap_lock);
2098
2099 // Read the GC count while holding the Heap_lock
2100 gc_count_before = total_collections();
2101 full_gc_count_before = total_full_collections();
2102 old_marking_count_before = _old_marking_cycles_started;
2103 }
2104
2105 if (should_do_concurrent_full_gc(cause)) {
2106 // Schedule an initial-mark evacuation pause that will start a
2107 // concurrent cycle. We're setting word_size to 0 which means that
2108 // we are not requesting a post-GC allocation.
2109 VM_G1CollectForAllocation op(0, /* word_size */
2110 gc_count_before,
2111 cause,
2112 true, /* should_initiate_conc_mark */
2113 g1_policy()->max_pause_time_ms());
2114 VMThread::execute(&op);
2115 if (!op.pause_succeeded()) {
2116 if (old_marking_count_before == _old_marking_cycles_started) {
2117 retry_gc = op.should_retry_gc();
2118 } else {
2119 // A Full GC happened while we were trying to schedule the
2120 // initial-mark GC. No point in starting a new cycle given
2121 // that the whole heap was collected anyway.
2122 }
2123
2124 if (retry_gc) {
2125 if (GCLocker::is_active_and_needs_gc()) {
2126 GCLocker::stall_until_clear();
2127 }
2128 }
2129 }
2130 } else {
2131 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2132 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2133
2134 // Schedule a standard evacuation pause. We're setting word_size
2135 // to 0 which means that we are not requesting a post-GC allocation.
2136 VM_G1CollectForAllocation op(0, /* word_size */
2137 gc_count_before,
2138 cause,
2139 false, /* should_initiate_conc_mark */
2140 g1_policy()->max_pause_time_ms());
2141 VMThread::execute(&op);
2142 } else {
2143 // Schedule a Full GC.
2144 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2145 VMThread::execute(&op);
2146 }
2147 }
2148 } while (retry_gc);
2149 }
2150
2151 bool G1CollectedHeap::is_in(const void* p) const {
2152 if (_hrm.reserved().contains(p)) {
2153 // Given that we know that p is in the reserved space,
2154 // heap_region_containing() should successfully
2155 // return the containing region.
2156 HeapRegion* hr = heap_region_containing(p);
2157 return hr->is_in(p);
2158 } else {
2159 return false;
2160 }
2161 }
2162
2163 #ifdef ASSERT
2164 bool G1CollectedHeap::is_in_exact(const void* p) const {
2165 bool contains = reserved_region().contains(p);
2166 bool available = _hrm.is_available(addr_to_region((HeapWord*)p));
2167 if (contains && available) {
2168 return true;
2169 } else {
2170 return false;
2171 }
2172 }
2173 #endif
2174
2175 // Iteration functions.
2176
2177 // Iterates an ObjectClosure over all objects within a HeapRegion.
2178
2179 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2180 ObjectClosure* _cl;
2181 public:
2182 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2183 bool do_heap_region(HeapRegion* r) {
2184 if (!r->is_continues_humongous()) {
2185 r->object_iterate(_cl);
2186 }
2187 return false;
2188 }
2189 };
2190
2191 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2192 IterateObjectClosureRegionClosure blk(cl);
2193 heap_region_iterate(&blk);
2194 }
2195
2196 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2197 _hrm.iterate(cl);
2198 }
2199
2200 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2201 HeapRegionClaimer *hrclaimer,
2202 uint worker_id) const {
2203 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2204 }
2205
2206 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2207 HeapRegionClaimer *hrclaimer) const {
2208 _hrm.par_iterate(cl, hrclaimer, 0);
2209 }
2210
2211 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2212 _collection_set.iterate(cl);
2213 }
2214
2215 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2216 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2217 }
2218
2219 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2220 HeapRegion* hr = heap_region_containing(addr);
2221 return hr->block_start(addr);
2222 }
2223
2224 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2225 HeapRegion* hr = heap_region_containing(addr);
2226 return hr->block_size(addr);
2227 }
2228
2229 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2230 HeapRegion* hr = heap_region_containing(addr);
2231 return hr->block_is_obj(addr);
2232 }
2233
2234 bool G1CollectedHeap::supports_tlab_allocation() const {
2235 return true;
2236 }
2237
2238 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2239 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2240 }
2241
2242 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2243 return _eden.length() * HeapRegion::GrainBytes;
2244 }
2245
2246 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2247 // must be equal to the humongous object limit.
2248 size_t G1CollectedHeap::max_tlab_size() const {
2249 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2250 }
2251
2252 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2253 return _allocator->unsafe_max_tlab_alloc();
2254 }
2255
2256 size_t G1CollectedHeap::max_capacity() const {
2257 return _hrm.reserved().byte_size();
2258 }
2259
2260 jlong G1CollectedHeap::millis_since_last_gc() {
2261 // See the notes in GenCollectedHeap::millis_since_last_gc()
2262 // for more information about the implementation.
2263 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2264 _g1_policy->collection_pause_end_millis();
2265 if (ret_val < 0) {
2266 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2267 ". returning zero instead.", ret_val);
2268 return 0;
2269 }
2270 return ret_val;
2271 }
2272
2273 void G1CollectedHeap::deduplicate_string(oop str) {
2274 assert(java_lang_String::is_instance(str), "invariant");
2275
2276 if (G1StringDedup::is_enabled()) {
2277 G1StringDedup::deduplicate(str);
2278 }
2279 }
2280
2281 void G1CollectedHeap::prepare_for_verify() {
2282 _verifier->prepare_for_verify();
2283 }
2284
2285 void G1CollectedHeap::verify(VerifyOption vo) {
2286 _verifier->verify(vo);
2287 }
2288
2289 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2290 return true;
2291 }
2292
2293 const char* const* G1CollectedHeap::concurrent_phases() const {
2294 return _cm_thread->concurrent_phases();
2295 }
2296
2297 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2298 return _cm_thread->request_concurrent_phase(phase);
2299 }
2300
2301 class PrintRegionClosure: public HeapRegionClosure {
2302 outputStream* _st;
2303 public:
2304 PrintRegionClosure(outputStream* st) : _st(st) {}
2305 bool do_heap_region(HeapRegion* r) {
2306 r->print_on(_st);
2307 return false;
2308 }
2309 };
2310
2311 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2312 const HeapRegion* hr,
2313 const VerifyOption vo) const {
2314 switch (vo) {
2315 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2316 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2317 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2318 default: ShouldNotReachHere();
2319 }
2320 return false; // keep some compilers happy
2321 }
2322
2323 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2324 const VerifyOption vo) const {
2325 switch (vo) {
2326 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2327 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2328 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2329 default: ShouldNotReachHere();
2330 }
2331 return false; // keep some compilers happy
2332 }
2333
2334 void G1CollectedHeap::print_heap_regions() const {
2335 LogTarget(Trace, gc, heap, region) lt;
2336 if (lt.is_enabled()) {
2337 LogStream ls(lt);
2338 print_regions_on(&ls);
2339 }
2340 }
2341
2342 void G1CollectedHeap::print_on(outputStream* st) const {
2343 st->print(" %-20s", "garbage-first heap");
2344 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2345 capacity()/K, used_unlocked()/K);
2346 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2347 p2i(_hrm.reserved().start()),
2348 p2i(_hrm.reserved().end()));
2349 st->cr();
2350 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2351 uint young_regions = young_regions_count();
2352 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2353 (size_t) young_regions * HeapRegion::GrainBytes / K);
2354 uint survivor_regions = survivor_regions_count();
2355 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2356 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2357 st->cr();
2358 MetaspaceUtils::print_on(st);
2359 }
2360
2361 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2362 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2363 "HS=humongous(starts), HC=humongous(continues), "
2364 "CS=collection set, F=free, A=archive, "
2365 "TAMS=top-at-mark-start (previous, next)");
2366 PrintRegionClosure blk(st);
2367 heap_region_iterate(&blk);
2368 }
2369
2370 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2371 print_on(st);
2372
2373 // Print the per-region information.
2374 print_regions_on(st);
2375 }
2376
2377 void G1CollectedHeap::print_on_error(outputStream* st) const {
2378 this->CollectedHeap::print_on_error(st);
2379
2380 if (_cm != NULL) {
2381 st->cr();
2382 _cm->print_on_error(st);
2383 }
2384 }
2385
2386 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2387 workers()->print_worker_threads_on(st);
2388 _cm_thread->print_on(st);
2389 st->cr();
2390 _cm->print_worker_threads_on(st);
2391 _cr->print_threads_on(st);
2392 _young_gen_sampling_thread->print_on(st);
2393 if (G1StringDedup::is_enabled()) {
2394 G1StringDedup::print_worker_threads_on(st);
2395 }
2396 }
2397
2398 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2399 workers()->threads_do(tc);
2400 tc->do_thread(_cm_thread);
2401 _cm->threads_do(tc);
2402 _cr->threads_do(tc);
2403 tc->do_thread(_young_gen_sampling_thread);
2404 if (G1StringDedup::is_enabled()) {
2405 G1StringDedup::threads_do(tc);
2406 }
2407 }
2408
2409 void G1CollectedHeap::print_tracing_info() const {
2410 g1_rem_set()->print_summary_info();
2411 concurrent_mark()->print_summary_info();
2412 }
2413
2414 #ifndef PRODUCT
2415 // Helpful for debugging RSet issues.
2416
2417 class PrintRSetsClosure : public HeapRegionClosure {
2418 private:
2419 const char* _msg;
2420 size_t _occupied_sum;
2421
2422 public:
2423 bool do_heap_region(HeapRegion* r) {
2424 HeapRegionRemSet* hrrs = r->rem_set();
2425 size_t occupied = hrrs->occupied();
2426 _occupied_sum += occupied;
2427
2428 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2429 if (occupied == 0) {
2430 tty->print_cr(" RSet is empty");
2431 } else {
2432 hrrs->print();
2433 }
2434 tty->print_cr("----------");
2435 return false;
2436 }
2437
2438 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2439 tty->cr();
2440 tty->print_cr("========================================");
2441 tty->print_cr("%s", msg);
2442 tty->cr();
2443 }
2444
2445 ~PrintRSetsClosure() {
2446 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2447 tty->print_cr("========================================");
2448 tty->cr();
2449 }
2450 };
2451
2452 void G1CollectedHeap::print_cset_rsets() {
2453 PrintRSetsClosure cl("Printing CSet RSets");
2454 collection_set_iterate(&cl);
2455 }
2456
2457 void G1CollectedHeap::print_all_rsets() {
2458 PrintRSetsClosure cl("Printing All RSets");;
2459 heap_region_iterate(&cl);
2460 }
2461 #endif // PRODUCT
2462
2463 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2464
2465 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2466 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2467 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2468
2469 size_t eden_capacity_bytes =
2470 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2471
2472 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2473 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2474 eden_capacity_bytes, survivor_used_bytes, num_regions());
2475 }
2476
2477 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2478 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2479 stats->unused(), stats->used(), stats->region_end_waste(),
2480 stats->regions_filled(), stats->direct_allocated(),
2481 stats->failure_used(), stats->failure_waste());
2482 }
2483
2484 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2485 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2486 gc_tracer->report_gc_heap_summary(when, heap_summary);
2487
2488 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2489 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2490 }
2491
2492 G1CollectedHeap* G1CollectedHeap::heap() {
2493 CollectedHeap* heap = Universe::heap();
2494 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2495 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2496 return (G1CollectedHeap*)heap;
2497 }
2498
2499 void G1CollectedHeap::gc_prologue(bool full) {
2500 // always_do_update_barrier = false;
2501 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2502
2503 // This summary needs to be printed before incrementing total collections.
2504 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2505
2506 // Update common counters.
2507 increment_total_collections(full /* full gc */);
2508 if (full) {
2509 increment_old_marking_cycles_started();
2510 }
2511
2512 // Fill TLAB's and such
2513 double start = os::elapsedTime();
2514 ensure_parsability(true);
2515 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2516 }
2517
2518 void G1CollectedHeap::gc_epilogue(bool full) {
2519 // Update common counters.
2520 if (full) {
2521 // Update the number of full collections that have been completed.
2522 increment_old_marking_cycles_completed(false /* concurrent */);
2523 }
2524
2525 // We are at the end of the GC. Total collections has already been increased.
2526 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2527
2528 // FIXME: what is this about?
2529 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2530 // is set.
2531 #if COMPILER2_OR_JVMCI
2532 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2533 #endif
2534 // always_do_update_barrier = true;
2535
2536 double start = os::elapsedTime();
2537 resize_all_tlabs();
2538 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2539
2540 MemoryService::track_memory_usage();
2541 // We have just completed a GC. Update the soft reference
2542 // policy with the new heap occupancy
2543 Universe::update_heap_info_at_gc();
2544 }
2545
2546 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2547 uint gc_count_before,
2548 bool* succeeded,
2549 GCCause::Cause gc_cause) {
2550 assert_heap_not_locked_and_not_at_safepoint();
2551 VM_G1CollectForAllocation op(word_size,
2552 gc_count_before,
2553 gc_cause,
2554 false, /* should_initiate_conc_mark */
2555 g1_policy()->max_pause_time_ms());
2556 VMThread::execute(&op);
2557
2558 HeapWord* result = op.result();
2559 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2560 assert(result == NULL || ret_succeeded,
2561 "the result should be NULL if the VM did not succeed");
2562 *succeeded = ret_succeeded;
2563
2564 assert_heap_not_locked();
2565 return result;
2566 }
2567
2568 void G1CollectedHeap::do_concurrent_mark() {
2569 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2570 if (!_cm_thread->in_progress()) {
2571 _cm_thread->set_started();
2572 CGC_lock->notify();
2573 }
2574 }
2575
2576 size_t G1CollectedHeap::pending_card_num() {
2577 size_t extra_cards = 0;
2578 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2579 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2580 extra_cards += dcq.size();
2581 }
2582 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2583 size_t buffer_size = dcqs.buffer_size();
2584 size_t buffer_num = dcqs.completed_buffers_num();
2585
2586 return buffer_size * buffer_num + extra_cards;
2587 }
2588
2589 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2590 // We don't nominate objects with many remembered set entries, on
2591 // the assumption that such objects are likely still live.
2592 HeapRegionRemSet* rem_set = r->rem_set();
2593
2594 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2595 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2596 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2597 }
2598
2599 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2600 private:
2601 size_t _total_humongous;
2602 size_t _candidate_humongous;
2603
2604 DirtyCardQueue _dcq;
2605
2606 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2607 assert(region->is_starts_humongous(), "Must start a humongous object");
2608
2609 oop obj = oop(region->bottom());
2610
2611 // Dead objects cannot be eager reclaim candidates. Due to class
2612 // unloading it is unsafe to query their classes so we return early.
2613 if (g1h->is_obj_dead(obj, region)) {
2614 return false;
2615 }
2616
2617 // If we do not have a complete remembered set for the region, then we can
2618 // not be sure that we have all references to it.
2619 if (!region->rem_set()->is_complete()) {
2620 return false;
2621 }
2622 // Candidate selection must satisfy the following constraints
2623 // while concurrent marking is in progress:
2624 //
2625 // * In order to maintain SATB invariants, an object must not be
2626 // reclaimed if it was allocated before the start of marking and
2627 // has not had its references scanned. Such an object must have
2628 // its references (including type metadata) scanned to ensure no
2629 // live objects are missed by the marking process. Objects
2630 // allocated after the start of concurrent marking don't need to
2631 // be scanned.
2632 //
2633 // * An object must not be reclaimed if it is on the concurrent
2634 // mark stack. Objects allocated after the start of concurrent
2635 // marking are never pushed on the mark stack.
2636 //
2637 // Nominating only objects allocated after the start of concurrent
2638 // marking is sufficient to meet both constraints. This may miss
2639 // some objects that satisfy the constraints, but the marking data
2640 // structures don't support efficiently performing the needed
2641 // additional tests or scrubbing of the mark stack.
2642 //
2643 // However, we presently only nominate is_typeArray() objects.
2644 // A humongous object containing references induces remembered
2645 // set entries on other regions. In order to reclaim such an
2646 // object, those remembered sets would need to be cleaned up.
2647 //
2648 // We also treat is_typeArray() objects specially, allowing them
2649 // to be reclaimed even if allocated before the start of
2650 // concurrent mark. For this we rely on mark stack insertion to
2651 // exclude is_typeArray() objects, preventing reclaiming an object
2652 // that is in the mark stack. We also rely on the metadata for
2653 // such objects to be built-in and so ensured to be kept live.
2654 // Frequent allocation and drop of large binary blobs is an
2655 // important use case for eager reclaim, and this special handling
2656 // may reduce needed headroom.
2657
2658 return obj->is_typeArray() &&
2659 g1h->is_potential_eager_reclaim_candidate(region);
2660 }
2661
2662 public:
2663 RegisterHumongousWithInCSetFastTestClosure()
2664 : _total_humongous(0),
2665 _candidate_humongous(0),
2666 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2667 }
2668
2669 virtual bool do_heap_region(HeapRegion* r) {
2670 if (!r->is_starts_humongous()) {
2671 return false;
2672 }
2673 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2674
2675 bool is_candidate = humongous_region_is_candidate(g1h, r);
2676 uint rindex = r->hrm_index();
2677 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2678 if (is_candidate) {
2679 _candidate_humongous++;
2680 g1h->register_humongous_region_with_cset(rindex);
2681 // Is_candidate already filters out humongous object with large remembered sets.
2682 // If we have a humongous object with a few remembered sets, we simply flush these
2683 // remembered set entries into the DCQS. That will result in automatic
2684 // re-evaluation of their remembered set entries during the following evacuation
2685 // phase.
2686 if (!r->rem_set()->is_empty()) {
2687 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2688 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2689 G1CardTable* ct = g1h->card_table();
2690 HeapRegionRemSetIterator hrrs(r->rem_set());
2691 size_t card_index;
2692 while (hrrs.has_next(card_index)) {
2693 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2694 // The remembered set might contain references to already freed
2695 // regions. Filter out such entries to avoid failing card table
2696 // verification.
2697 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2698 if (*card_ptr != G1CardTable::dirty_card_val()) {
2699 *card_ptr = G1CardTable::dirty_card_val();
2700 _dcq.enqueue(card_ptr);
2701 }
2702 }
2703 }
2704 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2705 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2706 hrrs.n_yielded(), r->rem_set()->occupied());
2707 // We should only clear the card based remembered set here as we will not
2708 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2709 // (and probably never) we do not enter this path if there are other kind of
2710 // remembered sets for this region.
2711 r->rem_set()->clear_locked(true /* only_cardset */);
2712 // Clear_locked() above sets the state to Empty. However we want to continue
2713 // collecting remembered set entries for humongous regions that were not
2714 // reclaimed.
2715 r->rem_set()->set_state_complete();
2716 }
2717 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2718 }
2719 _total_humongous++;
2720
2721 return false;
2722 }
2723
2724 size_t total_humongous() const { return _total_humongous; }
2725 size_t candidate_humongous() const { return _candidate_humongous; }
2726
2727 void flush_rem_set_entries() { _dcq.flush(); }
2728 };
2729
2730 void G1CollectedHeap::register_humongous_regions_with_cset() {
2731 if (!G1EagerReclaimHumongousObjects) {
2732 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2733 return;
2734 }
2735 double time = os::elapsed_counter();
2736
2737 // Collect reclaim candidate information and register candidates with cset.
2738 RegisterHumongousWithInCSetFastTestClosure cl;
2739 heap_region_iterate(&cl);
2740
2741 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2742 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2743 cl.total_humongous(),
2744 cl.candidate_humongous());
2745 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2746
2747 // Finally flush all remembered set entries to re-check into the global DCQS.
2748 cl.flush_rem_set_entries();
2749 }
2750
2751 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2752 public:
2753 bool do_heap_region(HeapRegion* hr) {
2754 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2755 hr->verify_rem_set();
2756 }
2757 return false;
2758 }
2759 };
2760
2761 uint G1CollectedHeap::num_task_queues() const {
2762 return _task_queues->size();
2763 }
2764
2765 #if TASKQUEUE_STATS
2766 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2767 st->print_raw_cr("GC Task Stats");
2768 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2769 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2770 }
2771
2772 void G1CollectedHeap::print_taskqueue_stats() const {
2773 if (!log_is_enabled(Trace, gc, task, stats)) {
2774 return;
2775 }
2776 Log(gc, task, stats) log;
2777 ResourceMark rm;
2778 LogStream ls(log.trace());
2779 outputStream* st = &ls;
2780
2781 print_taskqueue_stats_hdr(st);
2782
2783 TaskQueueStats totals;
2784 const uint n = num_task_queues();
2785 for (uint i = 0; i < n; ++i) {
2786 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2787 totals += task_queue(i)->stats;
2788 }
2789 st->print_raw("tot "); totals.print(st); st->cr();
2790
2791 DEBUG_ONLY(totals.verify());
2792 }
2793
2794 void G1CollectedHeap::reset_taskqueue_stats() {
2795 const uint n = num_task_queues();
2796 for (uint i = 0; i < n; ++i) {
2797 task_queue(i)->stats.reset();
2798 }
2799 }
2800 #endif // TASKQUEUE_STATS
2801
2802 void G1CollectedHeap::wait_for_root_region_scanning() {
2803 double scan_wait_start = os::elapsedTime();
2804 // We have to wait until the CM threads finish scanning the
2805 // root regions as it's the only way to ensure that all the
2806 // objects on them have been correctly scanned before we start
2807 // moving them during the GC.
2808 bool waited = _cm->root_regions()->wait_until_scan_finished();
2809 double wait_time_ms = 0.0;
2810 if (waited) {
2811 double scan_wait_end = os::elapsedTime();
2812 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2813 }
2814 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2815 }
2816
2817 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2818 private:
2819 G1HRPrinter* _hr_printer;
2820 public:
2821 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2822
2823 virtual bool do_heap_region(HeapRegion* r) {
2824 _hr_printer->cset(r);
2825 return false;
2826 }
2827 };
2828
2829 void G1CollectedHeap::start_new_collection_set() {
2830 collection_set()->start_incremental_building();
2831
2832 clear_cset_fast_test();
2833
2834 guarantee(_eden.length() == 0, "eden should have been cleared");
2835 g1_policy()->transfer_survivors_to_cset(survivor());
2836 }
2837
2838 bool
2839 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2840 assert_at_safepoint_on_vm_thread();
2841 guarantee(!is_gc_active(), "collection is not reentrant");
2842
2843 if (GCLocker::check_active_before_gc()) {
2844 return false;
2845 }
2846
2847 _gc_timer_stw->register_gc_start();
2848
2849 GCIdMark gc_id_mark;
2850 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2851
2852 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2853 ResourceMark rm;
2854
2855 g1_policy()->note_gc_start();
2856
2857 wait_for_root_region_scanning();
2858
2859 print_heap_before_gc();
2860 print_heap_regions();
2861 trace_heap_before_gc(_gc_tracer_stw);
2862
2863 _verifier->verify_region_sets_optional();
2864 _verifier->verify_dirty_young_regions();
2865
2866 // We should not be doing initial mark unless the conc mark thread is running
2867 if (!_cm_thread->should_terminate()) {
2868 // This call will decide whether this pause is an initial-mark
2869 // pause. If it is, in_initial_mark_gc() will return true
2870 // for the duration of this pause.
2871 g1_policy()->decide_on_conc_mark_initiation();
2872 }
2873
2874 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2875 assert(!collector_state()->in_initial_mark_gc() ||
2876 collector_state()->in_young_only_phase(), "sanity");
2877
2878 // We also do not allow mixed GCs during marking.
2879 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2880
2881 // Record whether this pause is an initial mark. When the current
2882 // thread has completed its logging output and it's safe to signal
2883 // the CM thread, the flag's value in the policy has been reset.
2884 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2885
2886 // Inner scope for scope based logging, timers, and stats collection
2887 {
2888 EvacuationInfo evacuation_info;
2889
2890 if (collector_state()->in_initial_mark_gc()) {
2891 // We are about to start a marking cycle, so we increment the
2892 // full collection counter.
2893 increment_old_marking_cycles_started();
2894 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2895 }
2896
2897 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2898
2899 GCTraceCPUTime tcpu;
2900
2901 G1HeapVerifier::G1VerifyType verify_type;
2902 FormatBuffer<> gc_string("Pause Young ");
2903 if (collector_state()->in_initial_mark_gc()) {
2904 gc_string.append("(Concurrent Start)");
2905 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2906 } else if (collector_state()->in_young_only_phase()) {
2907 if (collector_state()->in_young_gc_before_mixed()) {
2908 gc_string.append("(Prepare Mixed)");
2909 } else {
2910 gc_string.append("(Normal)");
2911 }
2912 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2913 } else {
2914 gc_string.append("(Mixed)");
2915 verify_type = G1HeapVerifier::G1VerifyMixed;
2916 }
2917 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2918
2919 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2920 workers()->active_workers(),
2921 Threads::number_of_non_daemon_threads());
2922 active_workers = workers()->update_active_workers(active_workers);
2923 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2924
2925 G1MonitoringScope ms(g1mm(),
2926 false /* full_gc */,
2927 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2928
2929 G1HeapTransition heap_transition(this);
2930 size_t heap_used_bytes_before_gc = used();
2931
2932 // Don't dynamically change the number of GC threads this early. A value of
2933 // 0 is used to indicate serial work. When parallel work is done,
2934 // it will be set.
2935
2936 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2937 IsGCActiveMark x;
2938
2939 gc_prologue(false);
2940
2941 if (VerifyRememberedSets) {
2942 log_info(gc, verify)("[Verifying RemSets before GC]");
2943 VerifyRegionRemSetClosure v_cl;
2944 heap_region_iterate(&v_cl);
2945 }
2946
2947 _verifier->verify_before_gc(verify_type);
2948
2949 _verifier->check_bitmaps("GC Start");
2950
2951 #if COMPILER2_OR_JVMCI
2952 DerivedPointerTable::clear();
2953 #endif
2954
2955 // Please see comment in g1CollectedHeap.hpp and
2956 // G1CollectedHeap::ref_processing_init() to see how
2957 // reference processing currently works in G1.
2958
2959 // Enable discovery in the STW reference processor
2960 _ref_processor_stw->enable_discovery();
2961
2962 {
2963 // We want to temporarily turn off discovery by the
2964 // CM ref processor, if necessary, and turn it back on
2965 // on again later if we do. Using a scoped
2966 // NoRefDiscovery object will do this.
2967 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2968
2969 // Forget the current alloc region (we might even choose it to be part
2970 // of the collection set!).
2971 _allocator->release_mutator_alloc_region();
2972
2973 // This timing is only used by the ergonomics to handle our pause target.
2974 // It is unclear why this should not include the full pause. We will
2975 // investigate this in CR 7178365.
2976 //
2977 // Preserving the old comment here if that helps the investigation:
2978 //
2979 // The elapsed time induced by the start time below deliberately elides
2980 // the possible verification above.
2981 double sample_start_time_sec = os::elapsedTime();
2982
2983 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2984
2985 if (collector_state()->in_initial_mark_gc()) {
2986 concurrent_mark()->pre_initial_mark();
2987 }
2988
2989 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2990
2991 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2992
2993 register_humongous_regions_with_cset();
2994
2995 assert(_verifier->check_cset_fast_test(), "Inconsistency in the InCSetState table.");
2996
2997 // We call this after finalize_cset() to
2998 // ensure that the CSet has been finalized.
2999 _cm->verify_no_cset_oops();
3000
3001 if (_hr_printer.is_active()) {
3002 G1PrintCollectionSetClosure cl(&_hr_printer);
3003 _collection_set.iterate(&cl);
3004 }
3005
3006 // Initialize the GC alloc regions.
3007 _allocator->init_gc_alloc_regions(evacuation_info);
3008
3009 G1ParScanThreadStateSet per_thread_states(this,
3010 workers()->active_workers(),
3011 collection_set()->young_region_length(),
3012 collection_set()->optional_region_length());
3013 pre_evacuate_collection_set();
3014
3015 // Actually do the work...
3016 evacuate_collection_set(&per_thread_states);
3017 evacuate_optional_collection_set(&per_thread_states);
3018
3019 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3020
3021 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3022 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3023
3024 eagerly_reclaim_humongous_regions();
3025
3026 record_obj_copy_mem_stats();
3027 _survivor_evac_stats.adjust_desired_plab_sz();
3028 _old_evac_stats.adjust_desired_plab_sz();
3029
3030 double start = os::elapsedTime();
3031 start_new_collection_set();
3032 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3033
3034 if (evacuation_failed()) {
3035 double recalculate_used_start = os::elapsedTime();
3036 set_used(recalculate_used());
3037 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3038
3039 if (_archive_allocator != NULL) {
3040 _archive_allocator->clear_used();
3041 }
3042 for (uint i = 0; i < ParallelGCThreads; i++) {
3043 if (_evacuation_failed_info_array[i].has_failed()) {
3044 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3045 }
3046 }
3047 } else {
3048 // The "used" of the the collection set have already been subtracted
3049 // when they were freed. Add in the bytes evacuated.
3050 increase_used(g1_policy()->bytes_copied_during_gc());
3051 }
3052
3053 if (collector_state()->in_initial_mark_gc()) {
3054 // We have to do this before we notify the CM threads that
3055 // they can start working to make sure that all the
3056 // appropriate initialization is done on the CM object.
3057 concurrent_mark()->post_initial_mark();
3058 // Note that we don't actually trigger the CM thread at
3059 // this point. We do that later when we're sure that
3060 // the current thread has completed its logging output.
3061 }
3062
3063 allocate_dummy_regions();
3064
3065 _allocator->init_mutator_alloc_region();
3066
3067 {
3068 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3069 if (expand_bytes > 0) {
3070 size_t bytes_before = capacity();
3071 // No need for an ergo logging here,
3072 // expansion_amount() does this when it returns a value > 0.
3073 double expand_ms;
3074 if (!expand(expand_bytes, _workers, &expand_ms)) {
3075 // We failed to expand the heap. Cannot do anything about it.
3076 }
3077 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3078 }
3079 }
3080
3081 // We redo the verification but now wrt to the new CSet which
3082 // has just got initialized after the previous CSet was freed.
3083 _cm->verify_no_cset_oops();
3084
3085 // This timing is only used by the ergonomics to handle our pause target.
3086 // It is unclear why this should not include the full pause. We will
3087 // investigate this in CR 7178365.
3088 double sample_end_time_sec = os::elapsedTime();
3089 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3090 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3091 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3092
3093 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3094 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3095
3096 if (VerifyRememberedSets) {
3097 log_info(gc, verify)("[Verifying RemSets after GC]");
3098 VerifyRegionRemSetClosure v_cl;
3099 heap_region_iterate(&v_cl);
3100 }
3101
3102 _verifier->verify_after_gc(verify_type);
3103 _verifier->check_bitmaps("GC End");
3104
3105 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3106 _ref_processor_stw->verify_no_references_recorded();
3107
3108 // CM reference discovery will be re-enabled if necessary.
3109 }
3110
3111 #ifdef TRACESPINNING
3112 ParallelTaskTerminator::print_termination_counts();
3113 #endif
3114
3115 gc_epilogue(false);
3116 }
3117
3118 // Print the remainder of the GC log output.
3119 if (evacuation_failed()) {
3120 log_info(gc)("To-space exhausted");
3121 }
3122
3123 g1_policy()->print_phases();
3124 heap_transition.print();
3125
3126 // It is not yet to safe to tell the concurrent mark to
3127 // start as we have some optional output below. We don't want the
3128 // output from the concurrent mark thread interfering with this
3129 // logging output either.
3130
3131 _hrm.verify_optional();
3132 _verifier->verify_region_sets_optional();
3133
3134 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3135 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3136
3137 print_heap_after_gc();
3138 print_heap_regions();
3139 trace_heap_after_gc(_gc_tracer_stw);
3140
3141 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3142 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3143 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3144 // before any GC notifications are raised.
3145 g1mm()->update_sizes();
3146
3147 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3148 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3149 _gc_timer_stw->register_gc_end();
3150 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3151 }
3152 // It should now be safe to tell the concurrent mark thread to start
3153 // without its logging output interfering with the logging output
3154 // that came from the pause.
3155
3156 if (should_start_conc_mark) {
3157 // CAUTION: after the doConcurrentMark() call below,
3158 // the concurrent marking thread(s) could be running
3159 // concurrently with us. Make sure that anything after
3160 // this point does not assume that we are the only GC thread
3161 // running. Note: of course, the actual marking work will
3162 // not start until the safepoint itself is released in
3163 // SuspendibleThreadSet::desynchronize().
3164 do_concurrent_mark();
3165 }
3166
3167 return true;
3168 }
3169
3170 void G1CollectedHeap::remove_self_forwarding_pointers() {
3171 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3172 workers()->run_task(&rsfp_task);
3173 }
3174
3175 void G1CollectedHeap::restore_after_evac_failure() {
3176 double remove_self_forwards_start = os::elapsedTime();
3177
3178 remove_self_forwarding_pointers();
3179 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3180 _preserved_marks_set.restore(&task_executor);
3181
3182 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3183 }
3184
3185 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3186 if (!_evacuation_failed) {
3187 _evacuation_failed = true;
3188 }
3189
3190 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3191 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3192 }
3193
3194 bool G1ParEvacuateFollowersClosure::offer_termination() {
3195 EventGCPhaseParallel event;
3196 G1ParScanThreadState* const pss = par_scan_state();
3197 start_term_time();
3198 const bool res = terminator()->offer_termination();
3199 end_term_time();
3200 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3201 return res;
3202 }
3203
3204 void G1ParEvacuateFollowersClosure::do_void() {
3205 EventGCPhaseParallel event;
3206 G1ParScanThreadState* const pss = par_scan_state();
3207 pss->trim_queue();
3208 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3209 do {
3210 EventGCPhaseParallel event;
3211 pss->steal_and_trim_queue(queues());
3212 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3213 } while (!offer_termination());
3214 }
3215
3216 class G1ParTask : public AbstractGangTask {
3217 protected:
3218 G1CollectedHeap* _g1h;
3219 G1ParScanThreadStateSet* _pss;
3220 RefToScanQueueSet* _queues;
3221 G1RootProcessor* _root_processor;
3222 TaskTerminator _terminator;
3223 uint _n_workers;
3224
3225 public:
3226 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3227 : AbstractGangTask("G1 collection"),
3228 _g1h(g1h),
3229 _pss(per_thread_states),
3230 _queues(task_queues),
3231 _root_processor(root_processor),
3232 _terminator(n_workers, _queues),
3233 _n_workers(n_workers)
3234 {}
3235
3236 void work(uint worker_id) {
3237 if (worker_id >= _n_workers) return; // no work needed this round
3238
3239 double start_sec = os::elapsedTime();
3240 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3241
3242 {
3243 ResourceMark rm;
3244 HandleMark hm;
3245
3246 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3247
3248 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3249 pss->set_ref_discoverer(rp);
3250
3251 double start_strong_roots_sec = os::elapsedTime();
3252
3253 _root_processor->evacuate_roots(pss, worker_id);
3254
3255 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3256 // treating the nmethods visited to act as roots for concurrent marking.
3257 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3258 // objects copied by the current evacuation.
3259 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3260
3261 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3262
3263 double term_sec = 0.0;
3264 size_t evac_term_attempts = 0;
3265 {
3266 double start = os::elapsedTime();
3267 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, _terminator.terminator(), G1GCPhaseTimes::ObjCopy);
3268 evac.do_void();
3269
3270 evac_term_attempts = evac.term_attempts();
3271 term_sec = evac.term_time();
3272 double elapsed_sec = os::elapsedTime() - start;
3273
3274 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3275 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3276 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3277 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3278 }
3279
3280 assert(pss->queue_is_empty(), "should be empty");
3281
3282 if (log_is_enabled(Debug, gc, task, stats)) {
3283 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3284 size_t lab_waste;
3285 size_t lab_undo_waste;
3286 pss->waste(lab_waste, lab_undo_waste);
3287 _g1h->print_termination_stats(worker_id,
3288 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3289 strong_roots_sec * 1000.0, /* strong roots time */
3290 term_sec * 1000.0, /* evac term time */
3291 evac_term_attempts, /* evac term attempts */
3292 lab_waste, /* alloc buffer waste */
3293 lab_undo_waste /* undo waste */
3294 );
3295 }
3296
3297 // Close the inner scope so that the ResourceMark and HandleMark
3298 // destructors are executed here and are included as part of the
3299 // "GC Worker Time".
3300 }
3301 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3302 }
3303 };
3304
3305 void G1CollectedHeap::print_termination_stats_hdr() {
3306 log_debug(gc, task, stats)("GC Termination Stats");
3307 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3308 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3309 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3310 }
3311
3312 void G1CollectedHeap::print_termination_stats(uint worker_id,
3313 double elapsed_ms,
3314 double strong_roots_ms,
3315 double term_ms,
3316 size_t term_attempts,
3317 size_t alloc_buffer_waste,
3318 size_t undo_waste) const {
3319 log_debug(gc, task, stats)
3320 ("%3d %9.2f %9.2f %6.2f "
3321 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3322 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3323 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3324 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3325 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3326 alloc_buffer_waste * HeapWordSize / K,
3327 undo_waste * HeapWordSize / K);
3328 }
3329
3330 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3331 bool class_unloading_occurred) {
3332 uint n_workers = workers()->active_workers();
3333
3334 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3335 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3336 workers()->run_task(&g1_unlink_task);
3337 }
3338
3339 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3340 bool process_strings,
3341 bool process_string_dedup) {
3342 if (!process_strings && !process_string_dedup) {
3343 // Nothing to clean.
3344 return;
3345 }
3346
3347 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3348 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3349 workers()->run_task(&g1_unlink_task);
3350 }
3351
3352 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3353 private:
3354 DirtyCardQueueSet* _queue;
3355 G1CollectedHeap* _g1h;
3356 public:
3357 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3358 _queue(queue), _g1h(g1h) { }
3359
3360 virtual void work(uint worker_id) {
3361 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3362 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3363
3364 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3365 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3366
3367 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3368 }
3369 };
3370
3371 void G1CollectedHeap::redirty_logged_cards() {
3372 double redirty_logged_cards_start = os::elapsedTime();
3373
3374 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3375 dirty_card_queue_set().reset_for_par_iteration();
3376 workers()->run_task(&redirty_task);
3377
3378 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3379 dcq.merge_bufferlists(&dirty_card_queue_set());
3380 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3381
3382 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3383 }
3384
3385 // Weak Reference Processing support
3386
3387 bool G1STWIsAliveClosure::do_object_b(oop p) {
3388 // An object is reachable if it is outside the collection set,
3389 // or is inside and copied.
3390 return !_g1h->is_in_cset(p) || p->is_forwarded();
3391 }
3392
3393 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3394 assert(obj != NULL, "must not be NULL");
3395 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3396 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3397 // may falsely indicate that this is not the case here: however the collection set only
3398 // contains old regions when concurrent mark is not running.
3399 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3400 }
3401
3402 // Non Copying Keep Alive closure
3403 class G1KeepAliveClosure: public OopClosure {
3404 G1CollectedHeap*_g1h;
3405 public:
3406 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3407 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3408 void do_oop(oop* p) {
3409 oop obj = *p;
3410 assert(obj != NULL, "the caller should have filtered out NULL values");
3411
3412 const InCSetState cset_state =_g1h->in_cset_state(obj);
3413 if (!cset_state.is_in_cset_or_humongous()) {
3414 return;
3415 }
3416 if (cset_state.is_in_cset()) {
3417 assert( obj->is_forwarded(), "invariant" );
3418 *p = obj->forwardee();
3419 } else {
3420 assert(!obj->is_forwarded(), "invariant" );
3421 assert(cset_state.is_humongous(),
3422 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3423 _g1h->set_humongous_is_live(obj);
3424 }
3425 }
3426 };
3427
3428 // Copying Keep Alive closure - can be called from both
3429 // serial and parallel code as long as different worker
3430 // threads utilize different G1ParScanThreadState instances
3431 // and different queues.
3432
3433 class G1CopyingKeepAliveClosure: public OopClosure {
3434 G1CollectedHeap* _g1h;
3435 G1ParScanThreadState* _par_scan_state;
3436
3437 public:
3438 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3439 G1ParScanThreadState* pss):
3440 _g1h(g1h),
3441 _par_scan_state(pss)
3442 {}
3443
3444 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3445 virtual void do_oop( oop* p) { do_oop_work(p); }
3446
3447 template <class T> void do_oop_work(T* p) {
3448 oop obj = RawAccess<>::oop_load(p);
3449
3450 if (_g1h->is_in_cset_or_humongous(obj)) {
3451 // If the referent object has been forwarded (either copied
3452 // to a new location or to itself in the event of an
3453 // evacuation failure) then we need to update the reference
3454 // field and, if both reference and referent are in the G1
3455 // heap, update the RSet for the referent.
3456 //
3457 // If the referent has not been forwarded then we have to keep
3458 // it alive by policy. Therefore we have copy the referent.
3459 //
3460 // When the queue is drained (after each phase of reference processing)
3461 // the object and it's followers will be copied, the reference field set
3462 // to point to the new location, and the RSet updated.
3463 _par_scan_state->push_on_queue(p);
3464 }
3465 }
3466 };
3467
3468 // Serial drain queue closure. Called as the 'complete_gc'
3469 // closure for each discovered list in some of the
3470 // reference processing phases.
3471
3472 class G1STWDrainQueueClosure: public VoidClosure {
3473 protected:
3474 G1CollectedHeap* _g1h;
3475 G1ParScanThreadState* _par_scan_state;
3476
3477 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3478
3479 public:
3480 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3481 _g1h(g1h),
3482 _par_scan_state(pss)
3483 { }
3484
3485 void do_void() {
3486 G1ParScanThreadState* const pss = par_scan_state();
3487 pss->trim_queue();
3488 }
3489 };
3490
3491 // Parallel Reference Processing closures
3492
3493 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3494 // processing during G1 evacuation pauses.
3495
3496 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3497 private:
3498 G1CollectedHeap* _g1h;
3499 G1ParScanThreadStateSet* _pss;
3500 RefToScanQueueSet* _queues;
3501 WorkGang* _workers;
3502
3503 public:
3504 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3505 G1ParScanThreadStateSet* per_thread_states,
3506 WorkGang* workers,
3507 RefToScanQueueSet *task_queues) :
3508 _g1h(g1h),
3509 _pss(per_thread_states),
3510 _queues(task_queues),
3511 _workers(workers)
3512 {
3513 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3514 }
3515
3516 // Executes the given task using concurrent marking worker threads.
3517 virtual void execute(ProcessTask& task, uint ergo_workers);
3518 };
3519
3520 // Gang task for possibly parallel reference processing
3521
3522 class G1STWRefProcTaskProxy: public AbstractGangTask {
3523 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3524 ProcessTask& _proc_task;
3525 G1CollectedHeap* _g1h;
3526 G1ParScanThreadStateSet* _pss;
3527 RefToScanQueueSet* _task_queues;
3528 ParallelTaskTerminator* _terminator;
3529
3530 public:
3531 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3532 G1CollectedHeap* g1h,
3533 G1ParScanThreadStateSet* per_thread_states,
3534 RefToScanQueueSet *task_queues,
3535 ParallelTaskTerminator* terminator) :
3536 AbstractGangTask("Process reference objects in parallel"),
3537 _proc_task(proc_task),
3538 _g1h(g1h),
3539 _pss(per_thread_states),
3540 _task_queues(task_queues),
3541 _terminator(terminator)
3542 {}
3543
3544 virtual void work(uint worker_id) {
3545 // The reference processing task executed by a single worker.
3546 ResourceMark rm;
3547 HandleMark hm;
3548
3549 G1STWIsAliveClosure is_alive(_g1h);
3550
3551 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3552 pss->set_ref_discoverer(NULL);
3553
3554 // Keep alive closure.
3555 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3556
3557 // Complete GC closure
3558 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator, G1GCPhaseTimes::ObjCopy);
3559
3560 // Call the reference processing task's work routine.
3561 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3562
3563 // Note we cannot assert that the refs array is empty here as not all
3564 // of the processing tasks (specifically phase2 - pp2_work) execute
3565 // the complete_gc closure (which ordinarily would drain the queue) so
3566 // the queue may not be empty.
3567 }
3568 };
3569
3570 // Driver routine for parallel reference processing.
3571 // Creates an instance of the ref processing gang
3572 // task and has the worker threads execute it.
3573 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3574 assert(_workers != NULL, "Need parallel worker threads.");
3575
3576 assert(_workers->active_workers() >= ergo_workers,
3577 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3578 ergo_workers, _workers->active_workers());
3579 TaskTerminator terminator(ergo_workers, _queues);
3580 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, terminator.terminator());
3581
3582 _workers->run_task(&proc_task_proxy, ergo_workers);
3583 }
3584
3585 // End of weak reference support closures
3586
3587 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3588 double ref_proc_start = os::elapsedTime();
3589
3590 ReferenceProcessor* rp = _ref_processor_stw;
3591 assert(rp->discovery_enabled(), "should have been enabled");
3592
3593 // Closure to test whether a referent is alive.
3594 G1STWIsAliveClosure is_alive(this);
3595
3596 // Even when parallel reference processing is enabled, the processing
3597 // of JNI refs is serial and performed serially by the current thread
3598 // rather than by a worker. The following PSS will be used for processing
3599 // JNI refs.
3600
3601 // Use only a single queue for this PSS.
3602 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3603 pss->set_ref_discoverer(NULL);
3604 assert(pss->queue_is_empty(), "pre-condition");
3605
3606 // Keep alive closure.
3607 G1CopyingKeepAliveClosure keep_alive(this, pss);
3608
3609 // Serial Complete GC closure
3610 G1STWDrainQueueClosure drain_queue(this, pss);
3611
3612 // Setup the soft refs policy...
3613 rp->setup_policy(false);
3614
3615 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3616
3617 ReferenceProcessorStats stats;
3618 if (!rp->processing_is_mt()) {
3619 // Serial reference processing...
3620 stats = rp->process_discovered_references(&is_alive,
3621 &keep_alive,
3622 &drain_queue,
3623 NULL,
3624 pt);
3625 } else {
3626 uint no_of_gc_workers = workers()->active_workers();
3627
3628 // Parallel reference processing
3629 assert(no_of_gc_workers <= rp->max_num_queues(),
3630 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3631 no_of_gc_workers, rp->max_num_queues());
3632
3633 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3634 stats = rp->process_discovered_references(&is_alive,
3635 &keep_alive,
3636 &drain_queue,
3637 &par_task_executor,
3638 pt);
3639 }
3640
3641 _gc_tracer_stw->report_gc_reference_stats(stats);
3642
3643 // We have completed copying any necessary live referent objects.
3644 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3645
3646 make_pending_list_reachable();
3647
3648 rp->verify_no_references_recorded();
3649
3650 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3651 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3652 }
3653
3654 void G1CollectedHeap::make_pending_list_reachable() {
3655 if (collector_state()->in_initial_mark_gc()) {
3656 oop pll_head = Universe::reference_pending_list();
3657 if (pll_head != NULL) {
3658 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3659 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3660 }
3661 }
3662 }
3663
3664 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3665 double merge_pss_time_start = os::elapsedTime();
3666 per_thread_states->flush();
3667 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3668 }
3669
3670 void G1CollectedHeap::pre_evacuate_collection_set() {
3671 _expand_heap_after_alloc_failure = true;
3672 _evacuation_failed = false;
3673
3674 // Disable the hot card cache.
3675 _hot_card_cache->reset_hot_cache_claimed_index();
3676 _hot_card_cache->set_use_cache(false);
3677
3678 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3679 _preserved_marks_set.assert_empty();
3680
3681 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3682
3683 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3684 if (collector_state()->in_initial_mark_gc()) {
3685 double start_clear_claimed_marks = os::elapsedTime();
3686
3687 ClassLoaderDataGraph::clear_claimed_marks();
3688
3689 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3690 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3691 }
3692 }
3693
3694 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3695 // Should G1EvacuationFailureALot be in effect for this GC?
3696 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3697
3698 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3699
3700 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3701
3702 double start_par_time_sec = os::elapsedTime();
3703 double end_par_time_sec;
3704
3705 {
3706 const uint n_workers = workers()->active_workers();
3707 G1RootProcessor root_processor(this, n_workers);
3708 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3709
3710 print_termination_stats_hdr();
3711
3712 workers()->run_task(&g1_par_task);
3713 end_par_time_sec = os::elapsedTime();
3714
3715 // Closing the inner scope will execute the destructor
3716 // for the G1RootProcessor object. We record the current
3717 // elapsed time before closing the scope so that time
3718 // taken for the destructor is NOT included in the
3719 // reported parallel time.
3720 }
3721
3722 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3723 phase_times->record_par_time(par_time_ms);
3724
3725 double code_root_fixup_time_ms =
3726 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3727 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3728 }
3729
3730 class G1EvacuateOptionalRegionTask : public AbstractGangTask {
3731 G1CollectedHeap* _g1h;
3732 G1ParScanThreadStateSet* _per_thread_states;
3733 G1OptionalCSet* _optional;
3734 RefToScanQueueSet* _queues;
3735 ParallelTaskTerminator _terminator;
3736
3737 Tickspan trim_ticks(G1ParScanThreadState* pss) {
3738 Tickspan copy_time = pss->trim_ticks();
3739 pss->reset_trim_ticks();
3740 return copy_time;
3741 }
3742
3743 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3744 G1EvacuationRootClosures* root_cls = pss->closures();
3745 G1ScanObjsDuringScanRSClosure obj_cl(_g1h, pss);
3746
3747 size_t scanned = 0;
3748 size_t claimed = 0;
3749 size_t skipped = 0;
3750 size_t used_memory = 0;
3751
3752 Ticks start = Ticks::now();
3753 Tickspan copy_time;
3754
3755 for (uint i = _optional->current_index(); i < _optional->current_limit(); i++) {
3756 HeapRegion* hr = _optional->region_at(i);
3757 G1ScanRSForOptionalClosure scan_opt_cl(&obj_cl);
3758 pss->oops_into_optional_region(hr)->oops_do(&scan_opt_cl, root_cls->raw_strong_oops());
3759 copy_time += trim_ticks(pss);
3760
3761 G1ScanRSForRegionClosure scan_rs_cl(_g1h->g1_rem_set()->scan_state(), &obj_cl, pss, G1GCPhaseTimes::OptScanRS, worker_id);
3762 scan_rs_cl.do_heap_region(hr);
3763 copy_time += trim_ticks(pss);
3764 scanned += scan_rs_cl.cards_scanned();
3765 claimed += scan_rs_cl.cards_claimed();
3766 skipped += scan_rs_cl.cards_skipped();
3767
3768 // Chunk lists for this region is no longer needed.
3769 used_memory += pss->oops_into_optional_region(hr)->used_memory();
3770 }
3771
3772 Tickspan scan_time = (Ticks::now() - start) - copy_time;
3773 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3774 p->record_or_add_time_secs(G1GCPhaseTimes::OptScanRS, worker_id, scan_time.seconds());
3775 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, copy_time.seconds());
3776
3777 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, scanned, G1GCPhaseTimes::OptCSetScannedCards);
3778 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, claimed, G1GCPhaseTimes::OptCSetClaimedCards);
3779 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, skipped, G1GCPhaseTimes::OptCSetSkippedCards);
3780 p->record_or_add_thread_work_item(G1GCPhaseTimes::OptScanRS, worker_id, used_memory, G1GCPhaseTimes::OptCSetUsedMemory);
3781 }
3782
3783 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3784 Ticks start = Ticks::now();
3785 G1ParEvacuateFollowersClosure cl(_g1h, pss, _queues, &_terminator, G1GCPhaseTimes::OptObjCopy);
3786 cl.do_void();
3787
3788 Tickspan evac_time = (Ticks::now() - start);
3789 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3790 p->record_or_add_time_secs(G1GCPhaseTimes::OptObjCopy, worker_id, evac_time.seconds());
3791 assert(pss->trim_ticks().seconds() == 0.0, "Unexpected partial trimming done during optional evacuation");
3792 }
3793
3794 public:
3795 G1EvacuateOptionalRegionTask(G1CollectedHeap* g1h,
3796 G1ParScanThreadStateSet* per_thread_states,
3797 G1OptionalCSet* cset,
3798 RefToScanQueueSet* queues,
3799 uint n_workers) :
3800 AbstractGangTask("G1 Evacuation Optional Region Task"),
3801 _g1h(g1h),
3802 _per_thread_states(per_thread_states),
3803 _optional(cset),
3804 _queues(queues),
3805 _terminator(n_workers, _queues) {
3806 }
3807
3808 void work(uint worker_id) {
3809 ResourceMark rm;
3810 HandleMark hm;
3811
3812 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3813 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3814
3815 scan_roots(pss, worker_id);
3816 evacuate_live_objects(pss, worker_id);
3817 }
3818 };
3819
3820 void G1CollectedHeap::evacuate_optional_regions(G1ParScanThreadStateSet* per_thread_states, G1OptionalCSet* ocset) {
3821 class G1MarkScope : public MarkScope {};
3822 G1MarkScope code_mark_scope;
3823
3824 G1EvacuateOptionalRegionTask task(this, per_thread_states, ocset, _task_queues, workers()->active_workers());
3825 workers()->run_task(&task);
3826 }
3827
3828 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3829 G1OptionalCSet optional_cset(&_collection_set, per_thread_states);
3830 if (optional_cset.is_empty()) {
3831 return;
3832 }
3833
3834 if (evacuation_failed()) {
3835 return;
3836 }
3837
3838 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3839 const double gc_start_time_ms = phase_times->cur_collection_start_sec() * 1000.0;
3840
3841 double start_time_sec = os::elapsedTime();
3842
3843 do {
3844 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3845 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3846
3847 if (time_left_ms < 0) {
3848 log_trace(gc, ergo, cset)("Skipping %u optional regions, pause time exceeded %.3fms", optional_cset.size(), time_used_ms);
3849 break;
3850 }
3851
3852 optional_cset.prepare_evacuation(time_left_ms * _g1_policy->optional_evacuation_fraction());
3853 if (optional_cset.prepare_failed()) {
3854 log_trace(gc, ergo, cset)("Skipping %u optional regions, no regions can be evacuated in %.3fms", optional_cset.size(), time_left_ms);
3855 break;
3856 }
3857
3858 evacuate_optional_regions(per_thread_states, &optional_cset);
3859
3860 optional_cset.complete_evacuation();
3861 if (optional_cset.evacuation_failed()) {
3862 break;
3863 }
3864 } while (!optional_cset.is_empty());
3865
3866 phase_times->record_optional_evacuation((os::elapsedTime() - start_time_sec) * 1000.0);
3867 }
3868
3869 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3870 // Also cleans the card table from temporary duplicate detection information used
3871 // during UpdateRS/ScanRS.
3872 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3873
3874 // Process any discovered reference objects - we have
3875 // to do this _before_ we retire the GC alloc regions
3876 // as we may have to copy some 'reachable' referent
3877 // objects (and their reachable sub-graphs) that were
3878 // not copied during the pause.
3879 process_discovered_references(per_thread_states);
3880
3881 // FIXME
3882 // CM's reference processing also cleans up the string table.
3883 // Should we do that here also? We could, but it is a serial operation
3884 // and could significantly increase the pause time.
3885
3886 G1STWIsAliveClosure is_alive(this);
3887 G1KeepAliveClosure keep_alive(this);
3888
3889 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3890 g1_policy()->phase_times()->weak_phase_times());
3891
3892 if (G1StringDedup::is_enabled()) {
3893 double fixup_start = os::elapsedTime();
3894
3895 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3896
3897 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3898 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3899 }
3900
3901 if (evacuation_failed()) {
3902 restore_after_evac_failure();
3903
3904 // Reset the G1EvacuationFailureALot counters and flags
3905 // Note: the values are reset only when an actual
3906 // evacuation failure occurs.
3907 NOT_PRODUCT(reset_evacuation_should_fail();)
3908 }
3909
3910 _preserved_marks_set.assert_empty();
3911
3912 _allocator->release_gc_alloc_regions(evacuation_info);
3913
3914 merge_per_thread_state_info(per_thread_states);
3915
3916 // Reset and re-enable the hot card cache.
3917 // Note the counts for the cards in the regions in the
3918 // collection set are reset when the collection set is freed.
3919 _hot_card_cache->reset_hot_cache();
3920 _hot_card_cache->set_use_cache(true);
3921
3922 purge_code_root_memory();
3923
3924 redirty_logged_cards();
3925 #if COMPILER2_OR_JVMCI
3926 double start = os::elapsedTime();
3927 DerivedPointerTable::update_pointers();
3928 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3929 #endif
3930 g1_policy()->print_age_table();
3931 }
3932
3933 void G1CollectedHeap::record_obj_copy_mem_stats() {
3934 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3935
3936 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3937 create_g1_evac_summary(&_old_evac_stats));
3938 }
3939
3940 void G1CollectedHeap::free_region(HeapRegion* hr,
3941 FreeRegionList* free_list,
3942 bool skip_remset,
3943 bool skip_hot_card_cache,
3944 bool locked) {
3945 assert(!hr->is_free(), "the region should not be free");
3946 assert(!hr->is_empty(), "the region should not be empty");
3947 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3948 assert(free_list != NULL, "pre-condition");
3949
3950 if (G1VerifyBitmaps) {
3951 MemRegion mr(hr->bottom(), hr->end());
3952 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3953 }
3954
3955 // Clear the card counts for this region.
3956 // Note: we only need to do this if the region is not young
3957 // (since we don't refine cards in young regions).
3958 if (!skip_hot_card_cache && !hr->is_young()) {
3959 _hot_card_cache->reset_card_counts(hr);
3960 }
3961 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3962 _g1_policy->remset_tracker()->update_at_free(hr);
3963 free_list->add_ordered(hr);
3964 }
3965
3966 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3967 FreeRegionList* free_list) {
3968 assert(hr->is_humongous(), "this is only for humongous regions");
3969 assert(free_list != NULL, "pre-condition");
3970 hr->clear_humongous();
3971 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3972 }
3973
3974 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3975 const uint humongous_regions_removed) {
3976 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3977 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3978 _old_set.bulk_remove(old_regions_removed);
3979 _humongous_set.bulk_remove(humongous_regions_removed);
3980 }
3981
3982 }
3983
3984 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3985 assert(list != NULL, "list can't be null");
3986 if (!list->is_empty()) {
3987 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3988 _hrm.insert_list_into_free_list(list);
3989 }
3990 }
3991
3992 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3993 decrease_used(bytes);
3994 }
3995
3996 class G1FreeCollectionSetTask : public AbstractGangTask {
3997 private:
3998
3999 // Closure applied to all regions in the collection set to do work that needs to
4000 // be done serially in a single thread.
4001 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
4002 private:
4003 EvacuationInfo* _evacuation_info;
4004 const size_t* _surviving_young_words;
4005
4006 // Bytes used in successfully evacuated regions before the evacuation.
4007 size_t _before_used_bytes;
4008 // Bytes used in unsucessfully evacuated regions before the evacuation
4009 size_t _after_used_bytes;
4010
4011 size_t _bytes_allocated_in_old_since_last_gc;
4012
4013 size_t _failure_used_words;
4014 size_t _failure_waste_words;
4015
4016 FreeRegionList _local_free_list;
4017 public:
4018 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4019 HeapRegionClosure(),
4020 _evacuation_info(evacuation_info),
4021 _surviving_young_words(surviving_young_words),
4022 _before_used_bytes(0),
4023 _after_used_bytes(0),
4024 _bytes_allocated_in_old_since_last_gc(0),
4025 _failure_used_words(0),
4026 _failure_waste_words(0),
4027 _local_free_list("Local Region List for CSet Freeing") {
4028 }
4029
4030 virtual bool do_heap_region(HeapRegion* r) {
4031 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4032
4033 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
4034 g1h->clear_in_cset(r);
4035
4036 if (r->is_young()) {
4037 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
4038 "Young index %d is wrong for region %u of type %s with %u young regions",
4039 r->young_index_in_cset(),
4040 r->hrm_index(),
4041 r->get_type_str(),
4042 g1h->collection_set()->young_region_length());
4043 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
4044 r->record_surv_words_in_group(words_survived);
4045 }
4046
4047 if (!r->evacuation_failed()) {
4048 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
4049 _before_used_bytes += r->used();
4050 g1h->free_region(r,
4051 &_local_free_list,
4052 true, /* skip_remset */
4053 true, /* skip_hot_card_cache */
4054 true /* locked */);
4055 } else {
4056 r->uninstall_surv_rate_group();
4057 r->set_young_index_in_cset(-1);
4058 r->set_evacuation_failed(false);
4059 // When moving a young gen region to old gen, we "allocate" that whole region
4060 // there. This is in addition to any already evacuated objects. Notify the
4061 // policy about that.
4062 // Old gen regions do not cause an additional allocation: both the objects
4063 // still in the region and the ones already moved are accounted for elsewhere.
4064 if (r->is_young()) {
4065 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
4066 }
4067 // The region is now considered to be old.
4068 r->set_old();
4069 // Do some allocation statistics accounting. Regions that failed evacuation
4070 // are always made old, so there is no need to update anything in the young
4071 // gen statistics, but we need to update old gen statistics.
4072 size_t used_words = r->marked_bytes() / HeapWordSize;
4073
4074 _failure_used_words += used_words;
4075 _failure_waste_words += HeapRegion::GrainWords - used_words;
4076
4077 g1h->old_set_add(r);
4078 _after_used_bytes += r->used();
4079 }
4080 return false;
4081 }
4082
4083 void complete_work() {
4084 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4085
4086 _evacuation_info->set_regions_freed(_local_free_list.length());
4087 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
4088
4089 g1h->prepend_to_freelist(&_local_free_list);
4090 g1h->decrement_summary_bytes(_before_used_bytes);
4091
4092 G1Policy* policy = g1h->g1_policy();
4093 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
4094
4095 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
4096 }
4097 };
4098
4099 G1CollectionSet* _collection_set;
4100 G1SerialFreeCollectionSetClosure _cl;
4101 const size_t* _surviving_young_words;
4102
4103 size_t _rs_lengths;
4104
4105 volatile jint _serial_work_claim;
4106
4107 struct WorkItem {
4108 uint region_idx;
4109 bool is_young;
4110 bool evacuation_failed;
4111
4112 WorkItem(HeapRegion* r) {
4113 region_idx = r->hrm_index();
4114 is_young = r->is_young();
4115 evacuation_failed = r->evacuation_failed();
4116 }
4117 };
4118
4119 volatile size_t _parallel_work_claim;
4120 size_t _num_work_items;
4121 WorkItem* _work_items;
4122
4123 void do_serial_work() {
4124 // Need to grab the lock to be allowed to modify the old region list.
4125 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
4126 _collection_set->iterate(&_cl);
4127 }
4128
4129 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
4130 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4131
4132 HeapRegion* r = g1h->region_at(region_idx);
4133 assert(!g1h->is_on_master_free_list(r), "sanity");
4134
4135 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4136
4137 if (!is_young) {
4138 g1h->_hot_card_cache->reset_card_counts(r);
4139 }
4140
4141 if (!evacuation_failed) {
4142 r->rem_set()->clear_locked();
4143 }
4144 }
4145
4146 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4147 private:
4148 size_t _cur_idx;
4149 WorkItem* _work_items;
4150 public:
4151 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4152
4153 virtual bool do_heap_region(HeapRegion* r) {
4154 _work_items[_cur_idx++] = WorkItem(r);
4155 return false;
4156 }
4157 };
4158
4159 void prepare_work() {
4160 G1PrepareFreeCollectionSetClosure cl(_work_items);
4161 _collection_set->iterate(&cl);
4162 }
4163
4164 void complete_work() {
4165 _cl.complete_work();
4166
4167 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4168 policy->record_max_rs_lengths(_rs_lengths);
4169 policy->cset_regions_freed();
4170 }
4171 public:
4172 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4173 AbstractGangTask("G1 Free Collection Set"),
4174 _collection_set(collection_set),
4175 _cl(evacuation_info, surviving_young_words),
4176 _surviving_young_words(surviving_young_words),
4177 _rs_lengths(0),
4178 _serial_work_claim(0),
4179 _parallel_work_claim(0),
4180 _num_work_items(collection_set->region_length()),
4181 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4182 prepare_work();
4183 }
4184
4185 ~G1FreeCollectionSetTask() {
4186 complete_work();
4187 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4188 }
4189
4190 // Chunk size for work distribution. The chosen value has been determined experimentally
4191 // to be a good tradeoff between overhead and achievable parallelism.
4192 static uint chunk_size() { return 32; }
4193
4194 virtual void work(uint worker_id) {
4195 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4196
4197 // Claim serial work.
4198 if (_serial_work_claim == 0) {
4199 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4200 if (value == 0) {
4201 double serial_time = os::elapsedTime();
4202 do_serial_work();
4203 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4204 }
4205 }
4206
4207 // Start parallel work.
4208 double young_time = 0.0;
4209 bool has_young_time = false;
4210 double non_young_time = 0.0;
4211 bool has_non_young_time = false;
4212
4213 while (true) {
4214 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4215 size_t cur = end - chunk_size();
4216
4217 if (cur >= _num_work_items) {
4218 break;
4219 }
4220
4221 EventGCPhaseParallel event;
4222 double start_time = os::elapsedTime();
4223
4224 end = MIN2(end, _num_work_items);
4225
4226 for (; cur < end; cur++) {
4227 bool is_young = _work_items[cur].is_young;
4228
4229 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4230
4231 double end_time = os::elapsedTime();
4232 double time_taken = end_time - start_time;
4233 if (is_young) {
4234 young_time += time_taken;
4235 has_young_time = true;
4236 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4237 } else {
4238 non_young_time += time_taken;
4239 has_non_young_time = true;
4240 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4241 }
4242 start_time = end_time;
4243 }
4244 }
4245
4246 if (has_young_time) {
4247 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4248 }
4249 if (has_non_young_time) {
4250 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4251 }
4252 }
4253 };
4254
4255 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4256 _eden.clear();
4257
4258 double free_cset_start_time = os::elapsedTime();
4259
4260 {
4261 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4262 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4263
4264 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4265
4266 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4267 cl.name(),
4268 num_workers,
4269 _collection_set.region_length());
4270 workers()->run_task(&cl, num_workers);
4271 }
4272 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4273
4274 collection_set->clear();
4275 }
4276
4277 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4278 private:
4279 FreeRegionList* _free_region_list;
4280 HeapRegionSet* _proxy_set;
4281 uint _humongous_objects_reclaimed;
4282 uint _humongous_regions_reclaimed;
4283 size_t _freed_bytes;
4284 public:
4285
4286 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4287 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4288 }
4289
4290 virtual bool do_heap_region(HeapRegion* r) {
4291 if (!r->is_starts_humongous()) {
4292 return false;
4293 }
4294
4295 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4296
4297 oop obj = (oop)r->bottom();
4298 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4299
4300 // The following checks whether the humongous object is live are sufficient.
4301 // The main additional check (in addition to having a reference from the roots
4302 // or the young gen) is whether the humongous object has a remembered set entry.
4303 //
4304 // A humongous object cannot be live if there is no remembered set for it
4305 // because:
4306 // - there can be no references from within humongous starts regions referencing
4307 // the object because we never allocate other objects into them.
4308 // (I.e. there are no intra-region references that may be missed by the
4309 // remembered set)
4310 // - as soon there is a remembered set entry to the humongous starts region
4311 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4312 // until the end of a concurrent mark.
4313 //
4314 // It is not required to check whether the object has been found dead by marking
4315 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4316 // all objects allocated during that time are considered live.
4317 // SATB marking is even more conservative than the remembered set.
4318 // So if at this point in the collection there is no remembered set entry,
4319 // nobody has a reference to it.
4320 // At the start of collection we flush all refinement logs, and remembered sets
4321 // are completely up-to-date wrt to references to the humongous object.
4322 //
4323 // Other implementation considerations:
4324 // - never consider object arrays at this time because they would pose
4325 // considerable effort for cleaning up the the remembered sets. This is
4326 // required because stale remembered sets might reference locations that
4327 // are currently allocated into.
4328 uint region_idx = r->hrm_index();
4329 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4330 !r->rem_set()->is_empty()) {
4331 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",
4332 region_idx,
4333 (size_t)obj->size() * HeapWordSize,
4334 p2i(r->bottom()),
4335 r->rem_set()->occupied(),
4336 r->rem_set()->strong_code_roots_list_length(),
4337 next_bitmap->is_marked(r->bottom()),
4338 g1h->is_humongous_reclaim_candidate(region_idx),
4339 obj->is_typeArray()
4340 );
4341 return false;
4342 }
4343
4344 guarantee(obj->is_typeArray(),
4345 "Only eagerly reclaiming type arrays is supported, but the object "
4346 PTR_FORMAT " is not.", p2i(r->bottom()));
4347
4348 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",
4349 region_idx,
4350 (size_t)obj->size() * HeapWordSize,
4351 p2i(r->bottom()),
4352 r->rem_set()->occupied(),
4353 r->rem_set()->strong_code_roots_list_length(),
4354 next_bitmap->is_marked(r->bottom()),
4355 g1h->is_humongous_reclaim_candidate(region_idx),
4356 obj->is_typeArray()
4357 );
4358
4359 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4360 cm->humongous_object_eagerly_reclaimed(r);
4361 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4362 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4363 region_idx,
4364 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4365 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4366 _humongous_objects_reclaimed++;
4367 do {
4368 HeapRegion* next = g1h->next_region_in_humongous(r);
4369 _freed_bytes += r->used();
4370 r->set_containing_set(NULL);
4371 _humongous_regions_reclaimed++;
4372 g1h->free_humongous_region(r, _free_region_list);
4373 r = next;
4374 } while (r != NULL);
4375
4376 return false;
4377 }
4378
4379 uint humongous_objects_reclaimed() {
4380 return _humongous_objects_reclaimed;
4381 }
4382
4383 uint humongous_regions_reclaimed() {
4384 return _humongous_regions_reclaimed;
4385 }
4386
4387 size_t bytes_freed() const {
4388 return _freed_bytes;
4389 }
4390 };
4391
4392 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4393 assert_at_safepoint_on_vm_thread();
4394
4395 if (!G1EagerReclaimHumongousObjects ||
4396 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4397 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4398 return;
4399 }
4400
4401 double start_time = os::elapsedTime();
4402
4403 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4404
4405 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4406 heap_region_iterate(&cl);
4407
4408 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4409
4410 G1HRPrinter* hrp = hr_printer();
4411 if (hrp->is_active()) {
4412 FreeRegionListIterator iter(&local_cleanup_list);
4413 while (iter.more_available()) {
4414 HeapRegion* hr = iter.get_next();
4415 hrp->cleanup(hr);
4416 }
4417 }
4418
4419 prepend_to_freelist(&local_cleanup_list);
4420 decrement_summary_bytes(cl.bytes_freed());
4421
4422 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4423 cl.humongous_objects_reclaimed());
4424 }
4425
4426 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4427 public:
4428 virtual bool do_heap_region(HeapRegion* r) {
4429 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4430 G1CollectedHeap::heap()->clear_in_cset(r);
4431 r->set_young_index_in_cset(-1);
4432 return false;
4433 }
4434 };
4435
4436 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4437 G1AbandonCollectionSetClosure cl;
4438 collection_set->iterate(&cl);
4439
4440 collection_set->clear();
4441 collection_set->stop_incremental_building();
4442 }
4443
4444 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4445 return _allocator->is_retained_old_region(hr);
4446 }
4447
4448 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4449 _eden.add(hr);
4450 _g1_policy->set_region_eden(hr);
4451 }
4452
4453 #ifdef ASSERT
4454
4455 class NoYoungRegionsClosure: public HeapRegionClosure {
4456 private:
4457 bool _success;
4458 public:
4459 NoYoungRegionsClosure() : _success(true) { }
4460 bool do_heap_region(HeapRegion* r) {
4461 if (r->is_young()) {
4462 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4463 p2i(r->bottom()), p2i(r->end()));
4464 _success = false;
4465 }
4466 return false;
4467 }
4468 bool success() { return _success; }
4469 };
4470
4471 bool G1CollectedHeap::check_young_list_empty() {
4472 bool ret = (young_regions_count() == 0);
4473
4474 NoYoungRegionsClosure closure;
4475 heap_region_iterate(&closure);
4476 ret = ret && closure.success();
4477
4478 return ret;
4479 }
4480
4481 #endif // ASSERT
4482
4483 class TearDownRegionSetsClosure : public HeapRegionClosure {
4484 HeapRegionSet *_old_set;
4485
4486 public:
4487 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4488
4489 bool do_heap_region(HeapRegion* r) {
4490 if (r->is_old()) {
4491 _old_set->remove(r);
4492 } else if(r->is_young()) {
4493 r->uninstall_surv_rate_group();
4494 } else {
4495 // We ignore free regions, we'll empty the free list afterwards.
4496 // We ignore humongous and archive regions, we're not tearing down these
4497 // sets.
4498 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4499 "it cannot be another type");
4500 }
4501 return false;
4502 }
4503
4504 ~TearDownRegionSetsClosure() {
4505 assert(_old_set->is_empty(), "post-condition");
4506 }
4507 };
4508
4509 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4510 assert_at_safepoint_on_vm_thread();
4511
4512 if (!free_list_only) {
4513 TearDownRegionSetsClosure cl(&_old_set);
4514 heap_region_iterate(&cl);
4515
4516 // Note that emptying the _young_list is postponed and instead done as
4517 // the first step when rebuilding the regions sets again. The reason for
4518 // this is that during a full GC string deduplication needs to know if
4519 // a collected region was young or old when the full GC was initiated.
4520 }
4521 _hrm.remove_all_free_regions();
4522 }
4523
4524 void G1CollectedHeap::increase_used(size_t bytes) {
4525 _summary_bytes_used += bytes;
4526 }
4527
4528 void G1CollectedHeap::decrease_used(size_t bytes) {
4529 assert(_summary_bytes_used >= bytes,
4530 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4531 _summary_bytes_used, bytes);
4532 _summary_bytes_used -= bytes;
4533 }
4534
4535 void G1CollectedHeap::set_used(size_t bytes) {
4536 _summary_bytes_used = bytes;
4537 }
4538
4539 class RebuildRegionSetsClosure : public HeapRegionClosure {
4540 private:
4541 bool _free_list_only;
4542
4543 HeapRegionSet* _old_set;
4544 HeapRegionManager* _hrm;
4545
4546 size_t _total_used;
4547
4548 public:
4549 RebuildRegionSetsClosure(bool free_list_only,
4550 HeapRegionSet* old_set,
4551 HeapRegionManager* hrm) :
4552 _free_list_only(free_list_only),
4553 _old_set(old_set), _hrm(hrm), _total_used(0) {
4554 assert(_hrm->num_free_regions() == 0, "pre-condition");
4555 if (!free_list_only) {
4556 assert(_old_set->is_empty(), "pre-condition");
4557 }
4558 }
4559
4560 bool do_heap_region(HeapRegion* r) {
4561 if (r->is_empty()) {
4562 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4563 // Add free regions to the free list
4564 r->set_free();
4565 _hrm->insert_into_free_list(r);
4566 } else if (!_free_list_only) {
4567 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4568
4569 if (r->is_archive() || r->is_humongous()) {
4570 // We ignore archive and humongous regions. We left these sets unchanged.
4571 } else {
4572 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4573 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4574 r->move_to_old();
4575 _old_set->add(r);
4576 }
4577 _total_used += r->used();
4578 }
4579
4580 return false;
4581 }
4582
4583 size_t total_used() {
4584 return _total_used;
4585 }
4586 };
4587
4588 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4589 assert_at_safepoint_on_vm_thread();
4590
4591 if (!free_list_only) {
4592 _eden.clear();
4593 _survivor.clear();
4594 }
4595
4596 RebuildRegionSetsClosure cl(free_list_only, &_old_set, &_hrm);
4597 heap_region_iterate(&cl);
4598
4599 if (!free_list_only) {
4600 set_used(cl.total_used());
4601 if (_archive_allocator != NULL) {
4602 _archive_allocator->clear_used();
4603 }
4604 }
4605 assert(used() == recalculate_used(),
4606 "inconsistent used(), value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4607 used(), recalculate_used());
4608 }
4609
4610 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4611 HeapRegion* hr = heap_region_containing(p);
4612 return hr->is_in(p);
4613 }
4614
4615 // Methods for the mutator alloc region
4616
4617 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4618 bool force) {
4619 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4620 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4621 if (force || should_allocate) {
4622 HeapRegion* new_alloc_region = new_region(word_size,
4623 false /* is_old */,
4624 false /* do_expand */);
4625 if (new_alloc_region != NULL) {
4626 set_region_short_lived_locked(new_alloc_region);
4627 _hr_printer.alloc(new_alloc_region, !should_allocate);
4628 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4629 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4630 return new_alloc_region;
4631 }
4632 }
4633 return NULL;
4634 }
4635
4636 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4637 size_t allocated_bytes) {
4638 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4639 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4640
4641 collection_set()->add_eden_region(alloc_region);
4642 increase_used(allocated_bytes);
4643 _hr_printer.retire(alloc_region);
4644 // We update the eden sizes here, when the region is retired,
4645 // instead of when it's allocated, since this is the point that its
4646 // used space has been recorded in _summary_bytes_used.
4647 g1mm()->update_eden_size();
4648 }
4649
4650 // Methods for the GC alloc regions
4651
4652 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4653 if (dest.is_old()) {
4654 return true;
4655 } else {
4656 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4657 }
4658 }
4659
4660 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4661 assert(FreeList_lock->owned_by_self(), "pre-condition");
4662
4663 if (!has_more_regions(dest)) {
4664 return NULL;
4665 }
4666
4667 const bool is_survivor = dest.is_young();
4668
4669 HeapRegion* new_alloc_region = new_region(word_size,
4670 !is_survivor,
4671 true /* do_expand */);
4672 if (new_alloc_region != NULL) {
4673 if (is_survivor) {
4674 new_alloc_region->set_survivor();
4675 _survivor.add(new_alloc_region);
4676 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4677 } else {
4678 new_alloc_region->set_old();
4679 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4680 }
4681 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4682 _hr_printer.alloc(new_alloc_region);
4683 return new_alloc_region;
4684 }
4685 return NULL;
4686 }
4687
4688 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4689 size_t allocated_bytes,
4690 InCSetState dest) {
4691 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4692 if (dest.is_old()) {
4693 old_set_add(alloc_region);
4694 }
4695
4696 bool const during_im = collector_state()->in_initial_mark_gc();
4697 if (during_im && allocated_bytes > 0) {
4698 _cm->root_regions()->add(alloc_region);
4699 }
4700 _hr_printer.retire(alloc_region);
4701 }
4702
4703 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4704 bool expanded = false;
4705 uint index = _hrm.find_highest_free(&expanded);
4706
4707 if (index != G1_NO_HRM_INDEX) {
4708 if (expanded) {
4709 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4710 HeapRegion::GrainWords * HeapWordSize);
4711 }
4712 _hrm.allocate_free_regions_starting_at(index, 1);
4713 return region_at(index);
4714 }
4715 return NULL;
4716 }
4717
4718 // Optimized nmethod scanning
4719
4720 class RegisterNMethodOopClosure: public OopClosure {
4721 G1CollectedHeap* _g1h;
4722 nmethod* _nm;
4723
4724 template <class T> void do_oop_work(T* p) {
4725 T heap_oop = RawAccess<>::oop_load(p);
4726 if (!CompressedOops::is_null(heap_oop)) {
4727 oop obj = CompressedOops::decode_not_null(heap_oop);
4728 HeapRegion* hr = _g1h->heap_region_containing(obj);
4729 assert(!hr->is_continues_humongous(),
4730 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4731 " starting at " HR_FORMAT,
4732 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4733
4734 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4735 hr->add_strong_code_root_locked(_nm);
4736 }
4737 }
4738
4739 public:
4740 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4741 _g1h(g1h), _nm(nm) {}
4742
4743 void do_oop(oop* p) { do_oop_work(p); }
4744 void do_oop(narrowOop* p) { do_oop_work(p); }
4745 };
4746
4747 class UnregisterNMethodOopClosure: public OopClosure {
4748 G1CollectedHeap* _g1h;
4749 nmethod* _nm;
4750
4751 template <class T> void do_oop_work(T* p) {
4752 T heap_oop = RawAccess<>::oop_load(p);
4753 if (!CompressedOops::is_null(heap_oop)) {
4754 oop obj = CompressedOops::decode_not_null(heap_oop);
4755 HeapRegion* hr = _g1h->heap_region_containing(obj);
4756 assert(!hr->is_continues_humongous(),
4757 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4758 " starting at " HR_FORMAT,
4759 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4760
4761 hr->remove_strong_code_root(_nm);
4762 }
4763 }
4764
4765 public:
4766 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4767 _g1h(g1h), _nm(nm) {}
4768
4769 void do_oop(oop* p) { do_oop_work(p); }
4770 void do_oop(narrowOop* p) { do_oop_work(p); }
4771 };
4772
4773 // Returns true if the reference points to an object that
4774 // can move in an incremental collection.
4775 bool G1CollectedHeap::is_scavengable(oop obj) {
4776 HeapRegion* hr = heap_region_containing(obj);
4777 return !hr->is_pinned();
4778 }
4779
4780 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4781 guarantee(nm != NULL, "sanity");
4782 RegisterNMethodOopClosure reg_cl(this, nm);
4783 nm->oops_do(®_cl);
4784 }
4785
4786 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4787 guarantee(nm != NULL, "sanity");
4788 UnregisterNMethodOopClosure reg_cl(this, nm);
4789 nm->oops_do(®_cl, true);
4790 }
4791
4792 void G1CollectedHeap::purge_code_root_memory() {
4793 double purge_start = os::elapsedTime();
4794 G1CodeRootSet::purge();
4795 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4796 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4797 }
4798
4799 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4800 G1CollectedHeap* _g1h;
4801
4802 public:
4803 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4804 _g1h(g1h) {}
4805
4806 void do_code_blob(CodeBlob* cb) {
4807 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4808 if (nm == NULL) {
4809 return;
4810 }
4811
4812 if (ScavengeRootsInCode) {
4813 _g1h->register_nmethod(nm);
4814 }
4815 }
4816 };
4817
4818 void G1CollectedHeap::rebuild_strong_code_roots() {
4819 RebuildStrongCodeRootClosure blob_cl(this);
4820 CodeCache::blobs_do(&blob_cl);
4821 }
4822
4823 void G1CollectedHeap::initialize_serviceability() {
4824 _g1mm->initialize_serviceability();
4825 }
4826
4827 MemoryUsage G1CollectedHeap::memory_usage() {
4828 return _g1mm->memory_usage();
4829 }
4830
4831 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4832 return _g1mm->memory_managers();
4833 }
4834
4835 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4836 return _g1mm->memory_pools();
4837 }