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/heapRegion.inline.hpp"
61 #include "gc/g1/heapRegionRemSet.hpp"
62 #include "gc/g1/heapRegionSet.inline.hpp"
63 #include "gc/g1/vm_operations_g1.hpp"
64 #include "gc/shared/adaptiveSizePolicy.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 "logging/log.hpp"
81 #include "memory/allocation.hpp"
82 #include "memory/iterator.hpp"
83 #include "memory/metaspaceShared.inline.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) {
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::set_range_archive(ranges[i], false);
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(MetaspaceShared::is_archive_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 g1_rem_set()->cleanupHRRS();
1020
1021 // We may have added regions to the current incremental collection
1022 // set between the last GC or pause and now. We need to clear the
1023 // incremental collection set and then start rebuilding it afresh
1024 // after this full GC.
1025 abandon_collection_set(collection_set());
1026
1027 tear_down_region_sets(false /* free_list_only */);
1028 }
1029
1030 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1031 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1032 assert(used() == recalculate_used(), "Should be equal");
1033 _verifier->verify_region_sets_optional();
1034 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1035 _verifier->check_bitmaps("Full GC Start");
1036 }
1037
1038 void G1CollectedHeap::prepare_heap_for_mutators() {
1039 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1040 ClassLoaderDataGraph::purge();
1041 MetaspaceUtils::verify_metrics();
1042
1043 // Prepare heap for normal collections.
1044 assert(num_free_regions() == 0, "we should not have added any free regions");
1045 rebuild_region_sets(false /* free_list_only */);
1046 abort_refinement();
1047 resize_if_necessary_after_full_collection();
1048
1049 // Rebuild the strong code root lists for each region
1050 rebuild_strong_code_roots();
1051
1052 // Purge code root memory
1053 purge_code_root_memory();
1054
1055 // Start a new incremental collection set for the next pause
1056 start_new_collection_set();
1057
1058 _allocator->init_mutator_alloc_region();
1059
1060 // Post collection state updates.
1061 MetaspaceGC::compute_new_size();
1062 }
1063
1064 void G1CollectedHeap::abort_refinement() {
1065 if (_hot_card_cache->use_cache()) {
1066 _hot_card_cache->reset_hot_cache();
1067 }
1068
1069 // Discard all remembered set updates.
1070 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1071 assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
1072 }
1073
1074 void G1CollectedHeap::verify_after_full_collection() {
1075 _hrm->verify_optional();
1076 _verifier->verify_region_sets_optional();
1077 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1078 // Clear the previous marking bitmap, if needed for bitmap verification.
1079 // Note we cannot do this when we clear the next marking bitmap in
1080 // G1ConcurrentMark::abort() above since VerifyDuringGC verifies the
1081 // objects marked during a full GC against the previous bitmap.
1082 // But we need to clear it before calling check_bitmaps below since
1083 // the full GC has compacted objects and updated TAMS but not updated
1084 // the prev bitmap.
1085 if (G1VerifyBitmaps) {
1086 GCTraceTime(Debug, gc)("Clear Prev Bitmap for Verification");
1087 _cm->clear_prev_bitmap(workers());
1088 }
1089 // This call implicitly verifies that the next bitmap is clear after Full GC.
1090 _verifier->check_bitmaps("Full GC End");
1091
1092 // At this point there should be no regions in the
1093 // entire heap tagged as young.
1094 assert(check_young_list_empty(), "young list should be empty at this point");
1095
1096 // Note: since we've just done a full GC, concurrent
1097 // marking is no longer active. Therefore we need not
1098 // re-enable reference discovery for the CM ref processor.
1099 // That will be done at the start of the next marking cycle.
1100 // We also know that the STW processor should no longer
1101 // discover any new references.
1102 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1103 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1104 _ref_processor_stw->verify_no_references_recorded();
1105 _ref_processor_cm->verify_no_references_recorded();
1106 }
1107
1108 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1109 // Post collection logging.
1110 // We should do this after we potentially resize the heap so
1111 // that all the COMMIT / UNCOMMIT events are generated before
1112 // the compaction events.
1113 print_hrm_post_compaction();
1114 heap_transition->print();
1115 print_heap_after_gc();
1116 print_heap_regions();
1117 #ifdef TRACESPINNING
1118 ParallelTaskTerminator::print_termination_counts();
1119 #endif
1120 }
1121
1122 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1123 bool clear_all_soft_refs) {
1124 assert_at_safepoint_on_vm_thread();
1125
1126 if (GCLocker::check_active_before_gc()) {
1127 // Full GC was not completed.
1128 return false;
1129 }
1130
1131 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1132 soft_ref_policy()->should_clear_all_soft_refs();
1133
1134 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs);
1135 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1136
1137 collector.prepare_collection();
1138 collector.collect();
1139 collector.complete_collection();
1140
1141 // Full collection was successfully completed.
1142 return true;
1143 }
1144
1145 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1146 // Currently, there is no facility in the do_full_collection(bool) API to notify
1147 // the caller that the collection did not succeed (e.g., because it was locked
1148 // out by the GC locker). So, right now, we'll ignore the return value.
1149 bool dummy = do_full_collection(true, /* explicit_gc */
1150 clear_all_soft_refs);
1151 }
1152
1153 void G1CollectedHeap::resize_if_necessary_after_full_collection() {
1154 // Capacity, free and used after the GC counted as full regions to
1155 // include the waste in the following calculations.
1156 const size_t capacity_after_gc = capacity();
1157 const size_t used_after_gc = capacity_after_gc - unused_committed_regions_in_bytes();
1158
1159 // This is enforced in arguments.cpp.
1160 assert(MinHeapFreeRatio <= MaxHeapFreeRatio,
1161 "otherwise the code below doesn't make sense");
1162
1163 // We don't have floating point command-line arguments
1164 const double minimum_free_percentage = (double) MinHeapFreeRatio / 100.0;
1165 const double maximum_used_percentage = 1.0 - minimum_free_percentage;
1166 const double maximum_free_percentage = (double) MaxHeapFreeRatio / 100.0;
1167 const double minimum_used_percentage = 1.0 - maximum_free_percentage;
1168
1169 const size_t min_heap_size = collector_policy()->min_heap_byte_size();
1170 const size_t max_heap_size = collector_policy()->max_heap_byte_size();
1171
1172 // We have to be careful here as these two calculations can overflow
1173 // 32-bit size_t's.
1174 double used_after_gc_d = (double) used_after_gc;
1175 double minimum_desired_capacity_d = used_after_gc_d / maximum_used_percentage;
1176 double maximum_desired_capacity_d = used_after_gc_d / minimum_used_percentage;
1177
1178 // Let's make sure that they are both under the max heap size, which
1179 // by default will make them fit into a size_t.
1180 double desired_capacity_upper_bound = (double) max_heap_size;
1181 minimum_desired_capacity_d = MIN2(minimum_desired_capacity_d,
1182 desired_capacity_upper_bound);
1183 maximum_desired_capacity_d = MIN2(maximum_desired_capacity_d,
1184 desired_capacity_upper_bound);
1185
1186 // We can now safely turn them into size_t's.
1187 size_t minimum_desired_capacity = (size_t) minimum_desired_capacity_d;
1188 size_t maximum_desired_capacity = (size_t) maximum_desired_capacity_d;
1189
1190 // This assert only makes sense here, before we adjust them
1191 // with respect to the min and max heap size.
1192 assert(minimum_desired_capacity <= maximum_desired_capacity,
1193 "minimum_desired_capacity = " SIZE_FORMAT ", "
1194 "maximum_desired_capacity = " SIZE_FORMAT,
1195 minimum_desired_capacity, maximum_desired_capacity);
1196
1197 // Should not be greater than the heap max size. No need to adjust
1198 // it with respect to the heap min size as it's a lower bound (i.e.,
1199 // we'll try to make the capacity larger than it, not smaller).
1200 minimum_desired_capacity = MIN2(minimum_desired_capacity, max_heap_size);
1201 // Should not be less than the heap min size. No need to adjust it
1202 // with respect to the heap max size as it's an upper bound (i.e.,
1203 // we'll try to make the capacity smaller than it, not greater).
1204 maximum_desired_capacity = MAX2(maximum_desired_capacity, min_heap_size);
1205
1206 if (capacity_after_gc < minimum_desired_capacity) {
1207 // Don't expand unless it's significant
1208 size_t expand_bytes = minimum_desired_capacity - capacity_after_gc;
1209
1210 log_debug(gc, ergo, heap)("Attempt heap expansion (capacity lower than min desired capacity after Full GC). "
1211 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1212 "min_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1213 capacity_after_gc, used_after_gc, used(), minimum_desired_capacity, MinHeapFreeRatio);
1214
1215 expand(expand_bytes, _workers);
1216
1217 // No expansion, now see if we want to shrink
1218 } else if (capacity_after_gc > maximum_desired_capacity) {
1219 // Capacity too large, compute shrinking size
1220 size_t shrink_bytes = capacity_after_gc - maximum_desired_capacity;
1221
1222 log_debug(gc, ergo, heap)("Attempt heap shrinking (capacity higher than max desired capacity after Full GC). "
1223 "Capacity: " SIZE_FORMAT "B occupancy: " SIZE_FORMAT "B live: " SIZE_FORMAT "B "
1224 "maximum_desired_capacity: " SIZE_FORMAT "B (" UINTX_FORMAT " %%)",
1225 capacity_after_gc, used_after_gc, used(), maximum_desired_capacity, MaxHeapFreeRatio);
1226
1227 shrink(shrink_bytes);
1228 }
1229 }
1230
1231 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1232 bool do_gc,
1233 bool clear_all_soft_refs,
1234 bool expect_null_mutator_alloc_region,
1235 bool* gc_succeeded) {
1236 *gc_succeeded = true;
1237 // Let's attempt the allocation first.
1238 HeapWord* result =
1239 attempt_allocation_at_safepoint(word_size,
1240 expect_null_mutator_alloc_region);
1241 if (result != NULL) {
1242 return result;
1243 }
1244
1245 // In a G1 heap, we're supposed to keep allocation from failing by
1246 // incremental pauses. Therefore, at least for now, we'll favor
1247 // expansion over collection. (This might change in the future if we can
1248 // do something smarter than full collection to satisfy a failed alloc.)
1249 result = expand_and_allocate(word_size);
1250 if (result != NULL) {
1251 return result;
1252 }
1253
1254 if (do_gc) {
1255 // Expansion didn't work, we'll try to do a Full GC.
1256 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1257 clear_all_soft_refs);
1258 }
1259
1260 return NULL;
1261 }
1262
1263 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1264 bool* succeeded) {
1265 assert_at_safepoint_on_vm_thread();
1266
1267 // Attempts to allocate followed by Full GC.
1268 HeapWord* result =
1269 satisfy_failed_allocation_helper(word_size,
1270 true, /* do_gc */
1271 false, /* clear_all_soft_refs */
1272 false, /* expect_null_mutator_alloc_region */
1273 succeeded);
1274
1275 if (result != NULL || !*succeeded) {
1276 return result;
1277 }
1278
1279 // Attempts to allocate followed by Full GC that will collect all soft references.
1280 result = satisfy_failed_allocation_helper(word_size,
1281 true, /* do_gc */
1282 true, /* clear_all_soft_refs */
1283 true, /* expect_null_mutator_alloc_region */
1284 succeeded);
1285
1286 if (result != NULL || !*succeeded) {
1287 return result;
1288 }
1289
1290 // Attempts to allocate, no GC
1291 result = satisfy_failed_allocation_helper(word_size,
1292 false, /* do_gc */
1293 false, /* clear_all_soft_refs */
1294 true, /* expect_null_mutator_alloc_region */
1295 succeeded);
1296
1297 if (result != NULL) {
1298 return result;
1299 }
1300
1301 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1302 "Flag should have been handled and cleared prior to this point");
1303
1304 // What else? We might try synchronous finalization later. If the total
1305 // space available is large enough for the allocation, then a more
1306 // complete compaction phase than we've tried so far might be
1307 // appropriate.
1308 return NULL;
1309 }
1310
1311 // Attempting to expand the heap sufficiently
1312 // to support an allocation of the given "word_size". If
1313 // successful, perform the allocation and return the address of the
1314 // allocated block, or else "NULL".
1315
1316 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1317 assert_at_safepoint_on_vm_thread();
1318
1319 _verifier->verify_region_sets_optional();
1320
1321 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1322 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1323 word_size * HeapWordSize);
1324
1325
1326 if (expand(expand_bytes, _workers)) {
1327 _hrm->verify_optional();
1328 _verifier->verify_region_sets_optional();
1329 return attempt_allocation_at_safepoint(word_size,
1330 false /* expect_null_mutator_alloc_region */);
1331 }
1332 return NULL;
1333 }
1334
1335 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1336 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1337 aligned_expand_bytes = align_up(aligned_expand_bytes,
1338 HeapRegion::GrainBytes);
1339
1340 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1341 expand_bytes, aligned_expand_bytes);
1342
1343 if (is_maximal_no_gc()) {
1344 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1345 return false;
1346 }
1347
1348 double expand_heap_start_time_sec = os::elapsedTime();
1349 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1350 assert(regions_to_expand > 0, "Must expand by at least one region");
1351
1352 uint expanded_by = _hrm->expand_by(regions_to_expand, pretouch_workers);
1353 if (expand_time_ms != NULL) {
1354 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1355 }
1356
1357 if (expanded_by > 0) {
1358 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1359 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1360 g1_policy()->record_new_heap_size(num_regions());
1361 } else {
1362 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1363
1364 // The expansion of the virtual storage space was unsuccessful.
1365 // Let's see if it was because we ran out of swap.
1366 if (G1ExitOnExpansionFailure &&
1367 _hrm->available() >= regions_to_expand) {
1368 // We had head room...
1369 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1370 }
1371 }
1372 return regions_to_expand > 0;
1373 }
1374
1375 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1376 size_t aligned_shrink_bytes =
1377 ReservedSpace::page_align_size_down(shrink_bytes);
1378 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1379 HeapRegion::GrainBytes);
1380 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1381
1382 uint num_regions_removed = _hrm->shrink_by(num_regions_to_remove);
1383 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1384
1385
1386 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",
1387 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1388 if (num_regions_removed > 0) {
1389 g1_policy()->record_new_heap_size(num_regions());
1390 } else {
1391 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1392 }
1393 }
1394
1395 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1396 _verifier->verify_region_sets_optional();
1397
1398 // We should only reach here at the end of a Full GC which means we
1399 // should not not be holding to any GC alloc regions. The method
1400 // below will make sure of that and do any remaining clean up.
1401 _allocator->abandon_gc_alloc_regions();
1402
1403 // Instead of tearing down / rebuilding the free lists here, we
1404 // could instead use the remove_all_pending() method on free_list to
1405 // remove only the ones that we need to remove.
1406 tear_down_region_sets(true /* free_list_only */);
1407 shrink_helper(shrink_bytes);
1408 rebuild_region_sets(true /* free_list_only */);
1409
1410 _hrm->verify_optional();
1411 _verifier->verify_region_sets_optional();
1412 }
1413
1414 class OldRegionSetChecker : public HeapRegionSetChecker {
1415 public:
1416 void check_mt_safety() {
1417 // Master Old Set MT safety protocol:
1418 // (a) If we're at a safepoint, operations on the master old set
1419 // should be invoked:
1420 // - by the VM thread (which will serialize them), or
1421 // - by the GC workers while holding the FreeList_lock, if we're
1422 // at a safepoint for an evacuation pause (this lock is taken
1423 // anyway when an GC alloc region is retired so that a new one
1424 // is allocated from the free list), or
1425 // - by the GC workers while holding the OldSets_lock, if we're at a
1426 // safepoint for a cleanup pause.
1427 // (b) If we're not at a safepoint, operations on the master old set
1428 // should be invoked while holding the Heap_lock.
1429
1430 if (SafepointSynchronize::is_at_safepoint()) {
1431 guarantee(Thread::current()->is_VM_thread() ||
1432 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1433 "master old set MT safety protocol at a safepoint");
1434 } else {
1435 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1436 }
1437 }
1438 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1439 const char* get_description() { return "Old Regions"; }
1440 };
1441
1442 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1443 public:
1444 void check_mt_safety() {
1445 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1446 "May only change archive regions during initialization or safepoint.");
1447 }
1448 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1449 const char* get_description() { return "Archive Regions"; }
1450 };
1451
1452 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1453 public:
1454 void check_mt_safety() {
1455 // Humongous Set MT safety protocol:
1456 // (a) If we're at a safepoint, operations on the master humongous
1457 // set should be invoked by either the VM thread (which will
1458 // serialize them) or by the GC workers while holding the
1459 // OldSets_lock.
1460 // (b) If we're not at a safepoint, operations on the master
1461 // humongous set should be invoked while holding the Heap_lock.
1462
1463 if (SafepointSynchronize::is_at_safepoint()) {
1464 guarantee(Thread::current()->is_VM_thread() ||
1465 OldSets_lock->owned_by_self(),
1466 "master humongous set MT safety protocol at a safepoint");
1467 } else {
1468 guarantee(Heap_lock->owned_by_self(),
1469 "master humongous set MT safety protocol outside a safepoint");
1470 }
1471 }
1472 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1473 const char* get_description() { return "Humongous Regions"; }
1474 };
1475
1476 G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* collector_policy) :
1477 CollectedHeap(),
1478 _young_gen_sampling_thread(NULL),
1479 _workers(NULL),
1480 _collector_policy(collector_policy),
1481 _card_table(NULL),
1482 _soft_ref_policy(),
1483 _old_set("Old Region Set", new OldRegionSetChecker()),
1484 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1485 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1486 _bot(NULL),
1487 _listener(),
1488 _hrm(NULL),
1489 _is_hetero_heap(false),
1490 _allocator(NULL),
1491 _verifier(NULL),
1492 _summary_bytes_used(0),
1493 _archive_allocator(NULL),
1494 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1495 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1496 _expand_heap_after_alloc_failure(true),
1497 _g1mm(NULL),
1498 _humongous_reclaim_candidates(),
1499 _has_humongous_reclaim_candidates(false),
1500 _hr_printer(),
1501 _collector_state(),
1502 _old_marking_cycles_started(0),
1503 _old_marking_cycles_completed(0),
1504 _eden(),
1505 _survivor(),
1506 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1507 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1508 _g1_policy(new G1Policy(_gc_timer_stw)),
1509 _heap_sizing_policy(NULL),
1510 _collection_set(this, _g1_policy),
1511 _hot_card_cache(NULL),
1512 _g1_rem_set(NULL),
1513 _dirty_card_queue_set(false),
1514 _cm(NULL),
1515 _cm_thread(NULL),
1516 _cr(NULL),
1517 _task_queues(NULL),
1518 _evacuation_failed(false),
1519 _evacuation_failed_info_array(NULL),
1520 _preserved_marks_set(true /* in_c_heap */),
1521 #ifndef PRODUCT
1522 _evacuation_failure_alot_for_current_gc(false),
1523 _evacuation_failure_alot_gc_number(0),
1524 _evacuation_failure_alot_count(0),
1525 #endif
1526 _ref_processor_stw(NULL),
1527 _is_alive_closure_stw(this),
1528 _is_subject_to_discovery_stw(this),
1529 _ref_processor_cm(NULL),
1530 _is_alive_closure_cm(this),
1531 _is_subject_to_discovery_cm(this),
1532 _in_cset_fast_test() {
1533
1534 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1535 true /* are_GC_task_threads */,
1536 false /* are_ConcurrentGC_threads */);
1537 _workers->initialize_workers();
1538 _verifier = new G1HeapVerifier(this);
1539
1540 _allocator = new G1Allocator(this);
1541
1542 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _g1_policy->analytics());
1543
1544 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1545
1546 // Override the default _filler_array_max_size so that no humongous filler
1547 // objects are created.
1548 _filler_array_max_size = _humongous_object_threshold_in_words;
1549
1550 uint n_queues = ParallelGCThreads;
1551 _task_queues = new RefToScanQueueSet(n_queues);
1552
1553 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1554
1555 for (uint i = 0; i < n_queues; i++) {
1556 RefToScanQueue* q = new RefToScanQueue();
1557 q->initialize();
1558 _task_queues->register_queue(i, q);
1559 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1560 }
1561
1562 // Initialize the G1EvacuationFailureALot counters and flags.
1563 NOT_PRODUCT(reset_evacuation_should_fail();)
1564
1565 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1566 }
1567
1568 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1569 size_t size,
1570 size_t translation_factor) {
1571 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1572 // Allocate a new reserved space, preferring to use large pages.
1573 ReservedSpace rs(size, preferred_page_size);
1574 G1RegionToSpaceMapper* result =
1575 G1RegionToSpaceMapper::create_mapper(rs,
1576 size,
1577 rs.alignment(),
1578 HeapRegion::GrainBytes,
1579 translation_factor,
1580 mtGC);
1581
1582 os::trace_page_sizes_for_requested_size(description,
1583 size,
1584 preferred_page_size,
1585 rs.alignment(),
1586 rs.base(),
1587 rs.size());
1588
1589 return result;
1590 }
1591
1592 jint G1CollectedHeap::initialize_concurrent_refinement() {
1593 jint ecode = JNI_OK;
1594 _cr = G1ConcurrentRefine::create(&ecode);
1595 return ecode;
1596 }
1597
1598 jint G1CollectedHeap::initialize_young_gen_sampling_thread() {
1599 _young_gen_sampling_thread = new G1YoungRemSetSamplingThread();
1600 if (_young_gen_sampling_thread->osthread() == NULL) {
1601 vm_shutdown_during_initialization("Could not create G1YoungRemSetSamplingThread");
1602 return JNI_ENOMEM;
1603 }
1604 return JNI_OK;
1605 }
1606
1607 jint G1CollectedHeap::initialize() {
1608 os::enable_vtime();
1609
1610 // Necessary to satisfy locking discipline assertions.
1611
1612 MutexLocker x(Heap_lock);
1613
1614 // While there are no constraints in the GC code that HeapWordSize
1615 // be any particular value, there are multiple other areas in the
1616 // system which believe this to be true (e.g. oop->object_size in some
1617 // cases incorrectly returns the size in wordSize units rather than
1618 // HeapWordSize).
1619 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1620
1621 size_t init_byte_size = collector_policy()->initial_heap_byte_size();
1622 size_t max_byte_size = collector_policy()->max_heap_byte_size();
1623 size_t heap_alignment = collector_policy()->heap_alignment();
1624
1625 // Ensure that the sizes are properly aligned.
1626 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1627 Universe::check_alignment(max_byte_size, HeapRegion::GrainBytes, "g1 heap");
1628 Universe::check_alignment(max_byte_size, heap_alignment, "g1 heap");
1629
1630 // Reserve the maximum.
1631
1632 // When compressed oops are enabled, the preferred heap base
1633 // is calculated by subtracting the requested size from the
1634 // 32Gb boundary and using the result as the base address for
1635 // heap reservation. If the requested size is not aligned to
1636 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1637 // into the ReservedHeapSpace constructor) then the actual
1638 // base of the reserved heap may end up differing from the
1639 // address that was requested (i.e. the preferred heap base).
1640 // If this happens then we could end up using a non-optimal
1641 // compressed oops mode.
1642 if (AllocateOldGenAt != NULL) {
1643 _is_hetero_heap = true;
1644 max_byte_size *= 2;
1645 }
1646
1647 ReservedSpace heap_rs = Universe::reserve_heap(max_byte_size,
1648 heap_alignment);
1649
1650 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
1651
1652 // Create the barrier set for the entire reserved region.
1653 G1CardTable* ct = new G1CardTable(reserved_region());
1654 ct->initialize();
1655 G1BarrierSet* bs = new G1BarrierSet(ct);
1656 bs->initialize();
1657 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1658 BarrierSet::set_barrier_set(bs);
1659 _card_table = ct;
1660
1661 // Create the hot card cache.
1662 _hot_card_cache = new G1HotCardCache(this);
1663
1664 // Carve out the G1 part of the heap.
1665 ReservedSpace g1_rs = heap_rs.first_part(max_byte_size);
1666 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
1667 G1RegionToSpaceMapper* heap_storage =
1668 G1RegionToSpaceMapper::create_heap_mapper(g1_rs,
1669 g1_rs.size(),
1670 page_size,
1671 HeapRegion::GrainBytes,
1672 1,
1673 mtJavaHeap);
1674 os::trace_page_sizes("Heap",
1675 collector_policy()->min_heap_byte_size(),
1676 max_byte_size,
1677 page_size,
1678 heap_rs.base(),
1679 heap_rs.size());
1680 heap_storage->set_mapping_changed_listener(&_listener);
1681
1682 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1683 G1RegionToSpaceMapper* bot_storage =
1684 create_aux_memory_mapper("Block Offset Table",
1685 G1BlockOffsetTable::compute_size(g1_rs.size() / HeapWordSize),
1686 G1BlockOffsetTable::heap_map_factor());
1687
1688 G1RegionToSpaceMapper* cardtable_storage =
1689 create_aux_memory_mapper("Card Table",
1690 G1CardTable::compute_size(g1_rs.size() / HeapWordSize),
1691 G1CardTable::heap_map_factor());
1692
1693 G1RegionToSpaceMapper* card_counts_storage =
1694 create_aux_memory_mapper("Card Counts Table",
1695 G1CardCounts::compute_size(g1_rs.size() / HeapWordSize),
1696 G1CardCounts::heap_map_factor());
1697
1698 size_t bitmap_size = G1CMBitMap::compute_size(g1_rs.size());
1699 G1RegionToSpaceMapper* prev_bitmap_storage =
1700 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1701 G1RegionToSpaceMapper* next_bitmap_storage =
1702 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1703
1704 if (is_hetero_heap()) {
1705 _hrm = new HeapRegionManagerForHeteroHeap((uint)((max_byte_size / 2) / HeapRegion::GrainBytes /*heap size as num of regions*/));
1706 }
1707 else {
1708 _hrm = new HeapRegionManager();
1709 }
1710 _hrm->initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1711 _card_table->initialize(cardtable_storage);
1712 // Do later initialization work for concurrent refinement.
1713 _hot_card_cache->initialize(card_counts_storage);
1714
1715 // 6843694 - ensure that the maximum region index can fit
1716 // in the remembered set structures.
1717 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1718 guarantee((max_regions() - 1) <= max_region_idx, "too many regions");
1719
1720 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1721 // start within the first card.
1722 guarantee(g1_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1723 // Also create a G1 rem set.
1724 _g1_rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1725 _g1_rem_set->initialize(max_reserved_capacity(), max_regions());
1726
1727 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1728 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1729 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1730 "too many cards per region");
1731
1732 FreeRegionList::set_unrealistically_long_length(max_expandable_regions() + 1);
1733
1734 _bot = new G1BlockOffsetTable(reserved_region(), bot_storage);
1735
1736 {
1737 HeapWord* start = _hrm->reserved().start();
1738 HeapWord* end = _hrm->reserved().end();
1739 size_t granularity = HeapRegion::GrainBytes;
1740
1741 _in_cset_fast_test.initialize(start, end, granularity);
1742 _humongous_reclaim_candidates.initialize(start, end, granularity);
1743 }
1744
1745 // Create the G1ConcurrentMark data structure and thread.
1746 // (Must do this late, so that "max_regions" is defined.)
1747 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1748 if (_cm == NULL || !_cm->completed_initialization()) {
1749 vm_shutdown_during_initialization("Could not create/initialize G1ConcurrentMark");
1750 return JNI_ENOMEM;
1751 }
1752 _cm_thread = _cm->cm_thread();
1753
1754 // Now expand into the initial heap size.
1755 if (!expand(init_byte_size, _workers)) {
1756 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1757 return JNI_ENOMEM;
1758 }
1759
1760 // Perform any initialization actions delegated to the policy.
1761 g1_policy()->init(this, &_collection_set);
1762
1763 G1BarrierSet::satb_mark_queue_set().initialize(this,
1764 SATB_Q_CBL_mon,
1765 SATB_Q_FL_lock,
1766 G1SATBProcessCompletedThreshold,
1767 G1SATBBufferEnqueueingThresholdPercent,
1768 Shared_SATB_Q_lock);
1769
1770 jint ecode = initialize_concurrent_refinement();
1771 if (ecode != JNI_OK) {
1772 return ecode;
1773 }
1774
1775 ecode = initialize_young_gen_sampling_thread();
1776 if (ecode != JNI_OK) {
1777 return ecode;
1778 }
1779
1780 G1BarrierSet::dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1781 DirtyCardQ_FL_lock,
1782 (int)concurrent_refine()->yellow_zone(),
1783 (int)concurrent_refine()->red_zone(),
1784 Shared_DirtyCardQ_lock,
1785 NULL, // fl_owner
1786 true); // init_free_ids
1787
1788 dirty_card_queue_set().initialize(DirtyCardQ_CBL_mon,
1789 DirtyCardQ_FL_lock,
1790 -1, // never trigger processing
1791 -1, // no limit on length
1792 Shared_DirtyCardQ_lock,
1793 &G1BarrierSet::dirty_card_queue_set());
1794
1795 // Here we allocate the dummy HeapRegion that is required by the
1796 // G1AllocRegion class.
1797 HeapRegion* dummy_region = _hrm->get_dummy_region();
1798
1799 // We'll re-use the same region whether the alloc region will
1800 // require BOT updates or not and, if it doesn't, then a non-young
1801 // region will complain that it cannot support allocations without
1802 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1803 dummy_region->set_eden();
1804 // Make sure it's full.
1805 dummy_region->set_top(dummy_region->end());
1806 G1AllocRegion::setup(this, dummy_region);
1807
1808 _allocator->init_mutator_alloc_region();
1809
1810 // Do create of the monitoring and management support so that
1811 // values in the heap have been properly initialized.
1812 _g1mm = new G1MonitoringSupport(this);
1813
1814 G1StringDedup::initialize();
1815
1816 _preserved_marks_set.init(ParallelGCThreads);
1817
1818 _collection_set.initialize(max_regions());
1819
1820 return JNI_OK;
1821 }
1822
1823 void G1CollectedHeap::stop() {
1824 // Stop all concurrent threads. We do this to make sure these threads
1825 // do not continue to execute and access resources (e.g. logging)
1826 // that are destroyed during shutdown.
1827 _cr->stop();
1828 _young_gen_sampling_thread->stop();
1829 _cm_thread->stop();
1830 if (G1StringDedup::is_enabled()) {
1831 G1StringDedup::stop();
1832 }
1833 }
1834
1835 void G1CollectedHeap::safepoint_synchronize_begin() {
1836 SuspendibleThreadSet::synchronize();
1837 }
1838
1839 void G1CollectedHeap::safepoint_synchronize_end() {
1840 SuspendibleThreadSet::desynchronize();
1841 }
1842
1843 size_t G1CollectedHeap::conservative_max_heap_alignment() {
1844 return HeapRegion::max_region_size();
1845 }
1846
1847 void G1CollectedHeap::post_initialize() {
1848 CollectedHeap::post_initialize();
1849 ref_processing_init();
1850 }
1851
1852 void G1CollectedHeap::ref_processing_init() {
1853 // Reference processing in G1 currently works as follows:
1854 //
1855 // * There are two reference processor instances. One is
1856 // used to record and process discovered references
1857 // during concurrent marking; the other is used to
1858 // record and process references during STW pauses
1859 // (both full and incremental).
1860 // * Both ref processors need to 'span' the entire heap as
1861 // the regions in the collection set may be dotted around.
1862 //
1863 // * For the concurrent marking ref processor:
1864 // * Reference discovery is enabled at initial marking.
1865 // * Reference discovery is disabled and the discovered
1866 // references processed etc during remarking.
1867 // * Reference discovery is MT (see below).
1868 // * Reference discovery requires a barrier (see below).
1869 // * Reference processing may or may not be MT
1870 // (depending on the value of ParallelRefProcEnabled
1871 // and ParallelGCThreads).
1872 // * A full GC disables reference discovery by the CM
1873 // ref processor and abandons any entries on it's
1874 // discovered lists.
1875 //
1876 // * For the STW processor:
1877 // * Non MT discovery is enabled at the start of a full GC.
1878 // * Processing and enqueueing during a full GC is non-MT.
1879 // * During a full GC, references are processed after marking.
1880 //
1881 // * Discovery (may or may not be MT) is enabled at the start
1882 // of an incremental evacuation pause.
1883 // * References are processed near the end of a STW evacuation pause.
1884 // * For both types of GC:
1885 // * Discovery is atomic - i.e. not concurrent.
1886 // * Reference discovery will not need a barrier.
1887
1888 bool mt_processing = ParallelRefProcEnabled && (ParallelGCThreads > 1);
1889
1890 // Concurrent Mark ref processor
1891 _ref_processor_cm =
1892 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1893 mt_processing, // mt processing
1894 ParallelGCThreads, // degree of mt processing
1895 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1896 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1897 false, // Reference discovery is not atomic
1898 &_is_alive_closure_cm, // is alive closure
1899 true); // allow changes to number of processing threads
1900
1901 // STW ref processor
1902 _ref_processor_stw =
1903 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1904 mt_processing, // mt processing
1905 ParallelGCThreads, // degree of mt processing
1906 (ParallelGCThreads > 1), // mt discovery
1907 ParallelGCThreads, // degree of mt discovery
1908 true, // Reference discovery is atomic
1909 &_is_alive_closure_stw, // is alive closure
1910 true); // allow changes to number of processing threads
1911 }
1912
1913 CollectorPolicy* G1CollectedHeap::collector_policy() const {
1914 return _collector_policy;
1915 }
1916
1917 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1918 return &_soft_ref_policy;
1919 }
1920
1921 size_t G1CollectedHeap::capacity() const {
1922 return _hrm->length() * HeapRegion::GrainBytes;
1923 }
1924
1925 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1926 return _hrm->total_free_bytes();
1927 }
1928
1929 void G1CollectedHeap::iterate_hcc_closure(CardTableEntryClosure* cl, uint worker_i) {
1930 _hot_card_cache->drain(cl, worker_i);
1931 }
1932
1933 void G1CollectedHeap::iterate_dirty_card_closure(CardTableEntryClosure* cl, uint worker_i) {
1934 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1935 size_t n_completed_buffers = 0;
1936 while (dcqs.apply_closure_during_gc(cl, worker_i)) {
1937 n_completed_buffers++;
1938 }
1939 g1_policy()->phase_times()->record_thread_work_item(G1GCPhaseTimes::UpdateRS, worker_i, n_completed_buffers, G1GCPhaseTimes::UpdateRSProcessedBuffers);
1940 dcqs.clear_n_completed_buffers();
1941 assert(!dcqs.completed_buffers_exist_dirty(), "Completed buffers exist!");
1942 }
1943
1944 // Computes the sum of the storage used by the various regions.
1945 size_t G1CollectedHeap::used() const {
1946 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1947 if (_archive_allocator != NULL) {
1948 result += _archive_allocator->used();
1949 }
1950 return result;
1951 }
1952
1953 size_t G1CollectedHeap::used_unlocked() const {
1954 return _summary_bytes_used;
1955 }
1956
1957 class SumUsedClosure: public HeapRegionClosure {
1958 size_t _used;
1959 public:
1960 SumUsedClosure() : _used(0) {}
1961 bool do_heap_region(HeapRegion* r) {
1962 _used += r->used();
1963 return false;
1964 }
1965 size_t result() { return _used; }
1966 };
1967
1968 size_t G1CollectedHeap::recalculate_used() const {
1969 SumUsedClosure blk;
1970 heap_region_iterate(&blk);
1971 return blk.result();
1972 }
1973
1974 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1975 switch (cause) {
1976 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1977 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1978 case GCCause::_wb_conc_mark: return true;
1979 default : return false;
1980 }
1981 }
1982
1983 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1984 switch (cause) {
1985 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
1986 case GCCause::_g1_humongous_allocation: return true;
1987 default: return is_user_requested_concurrent_full_gc(cause);
1988 }
1989 }
1990
1991 #ifndef PRODUCT
1992 void G1CollectedHeap::allocate_dummy_regions() {
1993 // Let's fill up most of the region
1994 size_t word_size = HeapRegion::GrainWords - 1024;
1995 // And as a result the region we'll allocate will be humongous.
1996 guarantee(is_humongous(word_size), "sanity");
1997
1998 // _filler_array_max_size is set to humongous object threshold
1999 // but temporarily change it to use CollectedHeap::fill_with_object().
2000 SizeTFlagSetting fs(_filler_array_max_size, word_size);
2001
2002 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
2003 // Let's use the existing mechanism for the allocation
2004 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
2005 if (dummy_obj != NULL) {
2006 MemRegion mr(dummy_obj, word_size);
2007 CollectedHeap::fill_with_object(mr);
2008 } else {
2009 // If we can't allocate once, we probably cannot allocate
2010 // again. Let's get out of the loop.
2011 break;
2012 }
2013 }
2014 }
2015 #endif // !PRODUCT
2016
2017 void G1CollectedHeap::increment_old_marking_cycles_started() {
2018 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
2019 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
2020 "Wrong marking cycle count (started: %d, completed: %d)",
2021 _old_marking_cycles_started, _old_marking_cycles_completed);
2022
2023 _old_marking_cycles_started++;
2024 }
2025
2026 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent) {
2027 MonitorLockerEx x(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
2028
2029 // We assume that if concurrent == true, then the caller is a
2030 // concurrent thread that was joined the Suspendible Thread
2031 // Set. If there's ever a cheap way to check this, we should add an
2032 // assert here.
2033
2034 // Given that this method is called at the end of a Full GC or of a
2035 // concurrent cycle, and those can be nested (i.e., a Full GC can
2036 // interrupt a concurrent cycle), the number of full collections
2037 // completed should be either one (in the case where there was no
2038 // nesting) or two (when a Full GC interrupted a concurrent cycle)
2039 // behind the number of full collections started.
2040
2041 // This is the case for the inner caller, i.e. a Full GC.
2042 assert(concurrent ||
2043 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
2044 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
2045 "for inner caller (Full GC): _old_marking_cycles_started = %u "
2046 "is inconsistent with _old_marking_cycles_completed = %u",
2047 _old_marking_cycles_started, _old_marking_cycles_completed);
2048
2049 // This is the case for the outer caller, i.e. the concurrent cycle.
2050 assert(!concurrent ||
2051 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
2052 "for outer caller (concurrent cycle): "
2053 "_old_marking_cycles_started = %u "
2054 "is inconsistent with _old_marking_cycles_completed = %u",
2055 _old_marking_cycles_started, _old_marking_cycles_completed);
2056
2057 _old_marking_cycles_completed += 1;
2058
2059 // We need to clear the "in_progress" flag in the CM thread before
2060 // we wake up any waiters (especially when ExplicitInvokesConcurrent
2061 // is set) so that if a waiter requests another System.gc() it doesn't
2062 // incorrectly see that a marking cycle is still in progress.
2063 if (concurrent) {
2064 _cm_thread->set_idle();
2065 }
2066
2067 // This notify_all() will ensure that a thread that called
2068 // System.gc() with (with ExplicitGCInvokesConcurrent set or not)
2069 // and it's waiting for a full GC to finish will be woken up. It is
2070 // waiting in VM_G1CollectForAllocation::doit_epilogue().
2071 FullGCCount_lock->notify_all();
2072 }
2073
2074 void G1CollectedHeap::collect(GCCause::Cause cause) {
2075 assert_heap_not_locked();
2076
2077 uint gc_count_before;
2078 uint old_marking_count_before;
2079 uint full_gc_count_before;
2080 bool retry_gc;
2081
2082 do {
2083 retry_gc = false;
2084
2085 {
2086 MutexLocker ml(Heap_lock);
2087
2088 // Read the GC count while holding the Heap_lock
2089 gc_count_before = total_collections();
2090 full_gc_count_before = total_full_collections();
2091 old_marking_count_before = _old_marking_cycles_started;
2092 }
2093
2094 if (should_do_concurrent_full_gc(cause)) {
2095 // Schedule an initial-mark evacuation pause that will start a
2096 // concurrent cycle. We're setting word_size to 0 which means that
2097 // we are not requesting a post-GC allocation.
2098 VM_G1CollectForAllocation op(0, /* word_size */
2099 gc_count_before,
2100 cause,
2101 true, /* should_initiate_conc_mark */
2102 g1_policy()->max_pause_time_ms());
2103 VMThread::execute(&op);
2104 if (!op.pause_succeeded()) {
2105 if (old_marking_count_before == _old_marking_cycles_started) {
2106 retry_gc = op.should_retry_gc();
2107 } else {
2108 // A Full GC happened while we were trying to schedule the
2109 // initial-mark GC. No point in starting a new cycle given
2110 // that the whole heap was collected anyway.
2111 }
2112
2113 if (retry_gc) {
2114 if (GCLocker::is_active_and_needs_gc()) {
2115 GCLocker::stall_until_clear();
2116 }
2117 }
2118 }
2119 } else {
2120 if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2121 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2122
2123 // Schedule a standard evacuation pause. We're setting word_size
2124 // to 0 which means that we are not requesting a post-GC allocation.
2125 VM_G1CollectForAllocation op(0, /* word_size */
2126 gc_count_before,
2127 cause,
2128 false, /* should_initiate_conc_mark */
2129 g1_policy()->max_pause_time_ms());
2130 VMThread::execute(&op);
2131 } else {
2132 // Schedule a Full GC.
2133 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2134 VMThread::execute(&op);
2135 }
2136 }
2137 } while (retry_gc);
2138 }
2139
2140 bool G1CollectedHeap::is_in(const void* p) const {
2141 if (_hrm->reserved().contains(p)) {
2142 // Given that we know that p is in the reserved space,
2143 // heap_region_containing() should successfully
2144 // return the containing region.
2145 HeapRegion* hr = heap_region_containing(p);
2146 return hr->is_in(p);
2147 } else {
2148 return false;
2149 }
2150 }
2151
2152 #ifdef ASSERT
2153 bool G1CollectedHeap::is_in_exact(const void* p) const {
2154 bool contains = reserved_region().contains(p);
2155 bool available = _hrm->is_available(addr_to_region((HeapWord*)p));
2156 if (contains && available) {
2157 return true;
2158 } else {
2159 return false;
2160 }
2161 }
2162 #endif
2163
2164 // Iteration functions.
2165
2166 // Iterates an ObjectClosure over all objects within a HeapRegion.
2167
2168 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2169 ObjectClosure* _cl;
2170 public:
2171 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2172 bool do_heap_region(HeapRegion* r) {
2173 if (!r->is_continues_humongous()) {
2174 r->object_iterate(_cl);
2175 }
2176 return false;
2177 }
2178 };
2179
2180 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2181 IterateObjectClosureRegionClosure blk(cl);
2182 heap_region_iterate(&blk);
2183 }
2184
2185 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2186 _hrm->iterate(cl);
2187 }
2188
2189 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2190 HeapRegionClaimer *hrclaimer,
2191 uint worker_id) const {
2192 _hrm->par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2193 }
2194
2195 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2196 HeapRegionClaimer *hrclaimer) const {
2197 _hrm->par_iterate(cl, hrclaimer, 0);
2198 }
2199
2200 void G1CollectedHeap::collection_set_iterate(HeapRegionClosure* cl) {
2201 _collection_set.iterate(cl);
2202 }
2203
2204 void G1CollectedHeap::collection_set_iterate_from(HeapRegionClosure *cl, uint worker_id) {
2205 _collection_set.iterate_from(cl, worker_id, workers()->active_workers());
2206 }
2207
2208 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2209 HeapRegion* hr = heap_region_containing(addr);
2210 return hr->block_start(addr);
2211 }
2212
2213 size_t G1CollectedHeap::block_size(const HeapWord* addr) const {
2214 HeapRegion* hr = heap_region_containing(addr);
2215 return hr->block_size(addr);
2216 }
2217
2218 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2219 HeapRegion* hr = heap_region_containing(addr);
2220 return hr->block_is_obj(addr);
2221 }
2222
2223 bool G1CollectedHeap::supports_tlab_allocation() const {
2224 return true;
2225 }
2226
2227 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2228 return (_g1_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2229 }
2230
2231 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2232 return _eden.length() * HeapRegion::GrainBytes;
2233 }
2234
2235 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2236 // must be equal to the humongous object limit.
2237 size_t G1CollectedHeap::max_tlab_size() const {
2238 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2239 }
2240
2241 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2242 return _allocator->unsafe_max_tlab_alloc();
2243 }
2244
2245 size_t G1CollectedHeap::max_capacity() const {
2246 return _hrm->max_expandable_length() * HeapRegion::GrainBytes;
2247 }
2248
2249 size_t G1CollectedHeap::max_reserved_capacity() const {
2250 return _hrm->max_length() * HeapRegion::GrainBytes;
2251 }
2252
2253 jlong G1CollectedHeap::millis_since_last_gc() {
2254 // See the notes in GenCollectedHeap::millis_since_last_gc()
2255 // for more information about the implementation.
2256 jlong ret_val = (os::javaTimeNanos() / NANOSECS_PER_MILLISEC) -
2257 _g1_policy->collection_pause_end_millis();
2258 if (ret_val < 0) {
2259 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
2260 ". returning zero instead.", ret_val);
2261 return 0;
2262 }
2263 return ret_val;
2264 }
2265
2266 void G1CollectedHeap::deduplicate_string(oop str) {
2267 assert(java_lang_String::is_instance(str), "invariant");
2268
2269 if (G1StringDedup::is_enabled()) {
2270 G1StringDedup::deduplicate(str);
2271 }
2272 }
2273
2274 void G1CollectedHeap::prepare_for_verify() {
2275 _verifier->prepare_for_verify();
2276 }
2277
2278 void G1CollectedHeap::verify(VerifyOption vo) {
2279 _verifier->verify(vo);
2280 }
2281
2282 bool G1CollectedHeap::supports_concurrent_phase_control() const {
2283 return true;
2284 }
2285
2286 const char* const* G1CollectedHeap::concurrent_phases() const {
2287 return _cm_thread->concurrent_phases();
2288 }
2289
2290 bool G1CollectedHeap::request_concurrent_phase(const char* phase) {
2291 return _cm_thread->request_concurrent_phase(phase);
2292 }
2293
2294 class PrintRegionClosure: public HeapRegionClosure {
2295 outputStream* _st;
2296 public:
2297 PrintRegionClosure(outputStream* st) : _st(st) {}
2298 bool do_heap_region(HeapRegion* r) {
2299 r->print_on(_st);
2300 return false;
2301 }
2302 };
2303
2304 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2305 const HeapRegion* hr,
2306 const VerifyOption vo) const {
2307 switch (vo) {
2308 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2309 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2310 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2311 default: ShouldNotReachHere();
2312 }
2313 return false; // keep some compilers happy
2314 }
2315
2316 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2317 const VerifyOption vo) const {
2318 switch (vo) {
2319 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2320 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2321 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2322 default: ShouldNotReachHere();
2323 }
2324 return false; // keep some compilers happy
2325 }
2326
2327 void G1CollectedHeap::print_heap_regions() const {
2328 LogTarget(Trace, gc, heap, region) lt;
2329 if (lt.is_enabled()) {
2330 LogStream ls(lt);
2331 print_regions_on(&ls);
2332 }
2333 }
2334
2335 void G1CollectedHeap::print_on(outputStream* st) const {
2336 st->print(" %-20s", "garbage-first heap");
2337 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2338 capacity()/K, used_unlocked()/K);
2339 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2340 p2i(_hrm->reserved().start()),
2341 p2i(_hrm->reserved().end()));
2342 st->cr();
2343 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2344 uint young_regions = young_regions_count();
2345 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2346 (size_t) young_regions * HeapRegion::GrainBytes / K);
2347 uint survivor_regions = survivor_regions_count();
2348 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2349 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2350 st->cr();
2351 MetaspaceUtils::print_on(st);
2352 }
2353
2354 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2355 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2356 "HS=humongous(starts), HC=humongous(continues), "
2357 "CS=collection set, F=free, A=archive, "
2358 "TAMS=top-at-mark-start (previous, next)");
2359 PrintRegionClosure blk(st);
2360 heap_region_iterate(&blk);
2361 }
2362
2363 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2364 print_on(st);
2365
2366 // Print the per-region information.
2367 print_regions_on(st);
2368 }
2369
2370 void G1CollectedHeap::print_on_error(outputStream* st) const {
2371 this->CollectedHeap::print_on_error(st);
2372
2373 if (_cm != NULL) {
2374 st->cr();
2375 _cm->print_on_error(st);
2376 }
2377 }
2378
2379 void G1CollectedHeap::print_gc_threads_on(outputStream* st) const {
2380 workers()->print_worker_threads_on(st);
2381 _cm_thread->print_on(st);
2382 st->cr();
2383 _cm->print_worker_threads_on(st);
2384 _cr->print_threads_on(st);
2385 _young_gen_sampling_thread->print_on(st);
2386 if (G1StringDedup::is_enabled()) {
2387 G1StringDedup::print_worker_threads_on(st);
2388 }
2389 }
2390
2391 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2392 workers()->threads_do(tc);
2393 tc->do_thread(_cm_thread);
2394 _cm->threads_do(tc);
2395 _cr->threads_do(tc);
2396 tc->do_thread(_young_gen_sampling_thread);
2397 if (G1StringDedup::is_enabled()) {
2398 G1StringDedup::threads_do(tc);
2399 }
2400 }
2401
2402 void G1CollectedHeap::print_tracing_info() const {
2403 g1_rem_set()->print_summary_info();
2404 concurrent_mark()->print_summary_info();
2405 }
2406
2407 #ifndef PRODUCT
2408 // Helpful for debugging RSet issues.
2409
2410 class PrintRSetsClosure : public HeapRegionClosure {
2411 private:
2412 const char* _msg;
2413 size_t _occupied_sum;
2414
2415 public:
2416 bool do_heap_region(HeapRegion* r) {
2417 HeapRegionRemSet* hrrs = r->rem_set();
2418 size_t occupied = hrrs->occupied();
2419 _occupied_sum += occupied;
2420
2421 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2422 if (occupied == 0) {
2423 tty->print_cr(" RSet is empty");
2424 } else {
2425 hrrs->print();
2426 }
2427 tty->print_cr("----------");
2428 return false;
2429 }
2430
2431 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2432 tty->cr();
2433 tty->print_cr("========================================");
2434 tty->print_cr("%s", msg);
2435 tty->cr();
2436 }
2437
2438 ~PrintRSetsClosure() {
2439 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2440 tty->print_cr("========================================");
2441 tty->cr();
2442 }
2443 };
2444
2445 void G1CollectedHeap::print_cset_rsets() {
2446 PrintRSetsClosure cl("Printing CSet RSets");
2447 collection_set_iterate(&cl);
2448 }
2449
2450 void G1CollectedHeap::print_all_rsets() {
2451 PrintRSetsClosure cl("Printing All RSets");;
2452 heap_region_iterate(&cl);
2453 }
2454 #endif // PRODUCT
2455
2456 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2457
2458 size_t eden_used_bytes = heap()->eden_regions_count() * HeapRegion::GrainBytes;
2459 size_t survivor_used_bytes = heap()->survivor_regions_count() * HeapRegion::GrainBytes;
2460 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2461
2462 size_t eden_capacity_bytes =
2463 (g1_policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2464
2465 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2466 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2467 eden_capacity_bytes, survivor_used_bytes, num_regions());
2468 }
2469
2470 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2471 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2472 stats->unused(), stats->used(), stats->region_end_waste(),
2473 stats->regions_filled(), stats->direct_allocated(),
2474 stats->failure_used(), stats->failure_waste());
2475 }
2476
2477 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2478 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2479 gc_tracer->report_gc_heap_summary(when, heap_summary);
2480
2481 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2482 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2483 }
2484
2485 G1CollectedHeap* G1CollectedHeap::heap() {
2486 CollectedHeap* heap = Universe::heap();
2487 assert(heap != NULL, "Uninitialized access to G1CollectedHeap::heap()");
2488 assert(heap->kind() == CollectedHeap::G1, "Invalid name");
2489 return (G1CollectedHeap*)heap;
2490 }
2491
2492 void G1CollectedHeap::gc_prologue(bool full) {
2493 // always_do_update_barrier = false;
2494 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2495
2496 // This summary needs to be printed before incrementing total collections.
2497 g1_rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2498
2499 // Update common counters.
2500 increment_total_collections(full /* full gc */);
2501 if (full) {
2502 increment_old_marking_cycles_started();
2503 }
2504
2505 // Fill TLAB's and such
2506 double start = os::elapsedTime();
2507 ensure_parsability(true);
2508 g1_policy()->phase_times()->record_prepare_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2509 }
2510
2511 void G1CollectedHeap::gc_epilogue(bool full) {
2512 // Update common counters.
2513 if (full) {
2514 // Update the number of full collections that have been completed.
2515 increment_old_marking_cycles_completed(false /* concurrent */);
2516 }
2517
2518 // We are at the end of the GC. Total collections has already been increased.
2519 g1_rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2520
2521 // FIXME: what is this about?
2522 // I'm ignoring the "fill_newgen()" call if "alloc_event_enabled"
2523 // is set.
2524 #if COMPILER2_OR_JVMCI
2525 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2526 #endif
2527 // always_do_update_barrier = true;
2528
2529 double start = os::elapsedTime();
2530 resize_all_tlabs();
2531 g1_policy()->phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2532
2533 MemoryService::track_memory_usage();
2534 // We have just completed a GC. Update the soft reference
2535 // policy with the new heap occupancy
2536 Universe::update_heap_info_at_gc();
2537 }
2538
2539 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2540 uint gc_count_before,
2541 bool* succeeded,
2542 GCCause::Cause gc_cause) {
2543 assert_heap_not_locked_and_not_at_safepoint();
2544 VM_G1CollectForAllocation op(word_size,
2545 gc_count_before,
2546 gc_cause,
2547 false, /* should_initiate_conc_mark */
2548 g1_policy()->max_pause_time_ms());
2549 VMThread::execute(&op);
2550
2551 HeapWord* result = op.result();
2552 bool ret_succeeded = op.prologue_succeeded() && op.pause_succeeded();
2553 assert(result == NULL || ret_succeeded,
2554 "the result should be NULL if the VM did not succeed");
2555 *succeeded = ret_succeeded;
2556
2557 assert_heap_not_locked();
2558 return result;
2559 }
2560
2561 void G1CollectedHeap::do_concurrent_mark() {
2562 MutexLockerEx x(CGC_lock, Mutex::_no_safepoint_check_flag);
2563 if (!_cm_thread->in_progress()) {
2564 _cm_thread->set_started();
2565 CGC_lock->notify();
2566 }
2567 }
2568
2569 size_t G1CollectedHeap::pending_card_num() {
2570 size_t extra_cards = 0;
2571 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *curr = jtiwh.next(); ) {
2572 DirtyCardQueue& dcq = G1ThreadLocalData::dirty_card_queue(curr);
2573 extra_cards += dcq.size();
2574 }
2575 DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
2576 size_t buffer_size = dcqs.buffer_size();
2577 size_t buffer_num = dcqs.completed_buffers_num();
2578
2579 return buffer_size * buffer_num + extra_cards;
2580 }
2581
2582 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2583 // We don't nominate objects with many remembered set entries, on
2584 // the assumption that such objects are likely still live.
2585 HeapRegionRemSet* rem_set = r->rem_set();
2586
2587 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2588 rem_set->occupancy_less_or_equal_than(G1RSetSparseRegionEntries) :
2589 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2590 }
2591
2592 class RegisterHumongousWithInCSetFastTestClosure : public HeapRegionClosure {
2593 private:
2594 size_t _total_humongous;
2595 size_t _candidate_humongous;
2596
2597 DirtyCardQueue _dcq;
2598
2599 bool humongous_region_is_candidate(G1CollectedHeap* g1h, HeapRegion* region) const {
2600 assert(region->is_starts_humongous(), "Must start a humongous object");
2601
2602 oop obj = oop(region->bottom());
2603
2604 // Dead objects cannot be eager reclaim candidates. Due to class
2605 // unloading it is unsafe to query their classes so we return early.
2606 if (g1h->is_obj_dead(obj, region)) {
2607 return false;
2608 }
2609
2610 // If we do not have a complete remembered set for the region, then we can
2611 // not be sure that we have all references to it.
2612 if (!region->rem_set()->is_complete()) {
2613 return false;
2614 }
2615 // Candidate selection must satisfy the following constraints
2616 // while concurrent marking is in progress:
2617 //
2618 // * In order to maintain SATB invariants, an object must not be
2619 // reclaimed if it was allocated before the start of marking and
2620 // has not had its references scanned. Such an object must have
2621 // its references (including type metadata) scanned to ensure no
2622 // live objects are missed by the marking process. Objects
2623 // allocated after the start of concurrent marking don't need to
2624 // be scanned.
2625 //
2626 // * An object must not be reclaimed if it is on the concurrent
2627 // mark stack. Objects allocated after the start of concurrent
2628 // marking are never pushed on the mark stack.
2629 //
2630 // Nominating only objects allocated after the start of concurrent
2631 // marking is sufficient to meet both constraints. This may miss
2632 // some objects that satisfy the constraints, but the marking data
2633 // structures don't support efficiently performing the needed
2634 // additional tests or scrubbing of the mark stack.
2635 //
2636 // However, we presently only nominate is_typeArray() objects.
2637 // A humongous object containing references induces remembered
2638 // set entries on other regions. In order to reclaim such an
2639 // object, those remembered sets would need to be cleaned up.
2640 //
2641 // We also treat is_typeArray() objects specially, allowing them
2642 // to be reclaimed even if allocated before the start of
2643 // concurrent mark. For this we rely on mark stack insertion to
2644 // exclude is_typeArray() objects, preventing reclaiming an object
2645 // that is in the mark stack. We also rely on the metadata for
2646 // such objects to be built-in and so ensured to be kept live.
2647 // Frequent allocation and drop of large binary blobs is an
2648 // important use case for eager reclaim, and this special handling
2649 // may reduce needed headroom.
2650
2651 return obj->is_typeArray() &&
2652 g1h->is_potential_eager_reclaim_candidate(region);
2653 }
2654
2655 public:
2656 RegisterHumongousWithInCSetFastTestClosure()
2657 : _total_humongous(0),
2658 _candidate_humongous(0),
2659 _dcq(&G1BarrierSet::dirty_card_queue_set()) {
2660 }
2661
2662 virtual bool do_heap_region(HeapRegion* r) {
2663 if (!r->is_starts_humongous()) {
2664 return false;
2665 }
2666 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2667
2668 bool is_candidate = humongous_region_is_candidate(g1h, r);
2669 uint rindex = r->hrm_index();
2670 g1h->set_humongous_reclaim_candidate(rindex, is_candidate);
2671 if (is_candidate) {
2672 _candidate_humongous++;
2673 g1h->register_humongous_region_with_cset(rindex);
2674 // Is_candidate already filters out humongous object with large remembered sets.
2675 // If we have a humongous object with a few remembered sets, we simply flush these
2676 // remembered set entries into the DCQS. That will result in automatic
2677 // re-evaluation of their remembered set entries during the following evacuation
2678 // phase.
2679 if (!r->rem_set()->is_empty()) {
2680 guarantee(r->rem_set()->occupancy_less_or_equal_than(G1RSetSparseRegionEntries),
2681 "Found a not-small remembered set here. This is inconsistent with previous assumptions.");
2682 G1CardTable* ct = g1h->card_table();
2683 HeapRegionRemSetIterator hrrs(r->rem_set());
2684 size_t card_index;
2685 while (hrrs.has_next(card_index)) {
2686 jbyte* card_ptr = (jbyte*)ct->byte_for_index(card_index);
2687 // The remembered set might contain references to already freed
2688 // regions. Filter out such entries to avoid failing card table
2689 // verification.
2690 if (g1h->is_in_closed_subset(ct->addr_for(card_ptr))) {
2691 if (*card_ptr != G1CardTable::dirty_card_val()) {
2692 *card_ptr = G1CardTable::dirty_card_val();
2693 _dcq.enqueue(card_ptr);
2694 }
2695 }
2696 }
2697 assert(hrrs.n_yielded() == r->rem_set()->occupied(),
2698 "Remembered set hash maps out of sync, cur: " SIZE_FORMAT " entries, next: " SIZE_FORMAT " entries",
2699 hrrs.n_yielded(), r->rem_set()->occupied());
2700 // We should only clear the card based remembered set here as we will not
2701 // implicitly rebuild anything else during eager reclaim. Note that at the moment
2702 // (and probably never) we do not enter this path if there are other kind of
2703 // remembered sets for this region.
2704 r->rem_set()->clear_locked(true /* only_cardset */);
2705 // Clear_locked() above sets the state to Empty. However we want to continue
2706 // collecting remembered set entries for humongous regions that were not
2707 // reclaimed.
2708 r->rem_set()->set_state_complete();
2709 }
2710 assert(r->rem_set()->is_empty(), "At this point any humongous candidate remembered set must be empty.");
2711 }
2712 _total_humongous++;
2713
2714 return false;
2715 }
2716
2717 size_t total_humongous() const { return _total_humongous; }
2718 size_t candidate_humongous() const { return _candidate_humongous; }
2719
2720 void flush_rem_set_entries() { _dcq.flush(); }
2721 };
2722
2723 void G1CollectedHeap::register_humongous_regions_with_cset() {
2724 if (!G1EagerReclaimHumongousObjects) {
2725 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(0.0, 0, 0);
2726 return;
2727 }
2728 double time = os::elapsed_counter();
2729
2730 // Collect reclaim candidate information and register candidates with cset.
2731 RegisterHumongousWithInCSetFastTestClosure cl;
2732 heap_region_iterate(&cl);
2733
2734 time = ((double)(os::elapsed_counter() - time) / os::elapsed_frequency()) * 1000.0;
2735 g1_policy()->phase_times()->record_fast_reclaim_humongous_stats(time,
2736 cl.total_humongous(),
2737 cl.candidate_humongous());
2738 _has_humongous_reclaim_candidates = cl.candidate_humongous() > 0;
2739
2740 // Finally flush all remembered set entries to re-check into the global DCQS.
2741 cl.flush_rem_set_entries();
2742 }
2743
2744 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2745 public:
2746 bool do_heap_region(HeapRegion* hr) {
2747 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2748 hr->verify_rem_set();
2749 }
2750 return false;
2751 }
2752 };
2753
2754 uint G1CollectedHeap::num_task_queues() const {
2755 return _task_queues->size();
2756 }
2757
2758 #if TASKQUEUE_STATS
2759 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2760 st->print_raw_cr("GC Task Stats");
2761 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2762 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2763 }
2764
2765 void G1CollectedHeap::print_taskqueue_stats() const {
2766 if (!log_is_enabled(Trace, gc, task, stats)) {
2767 return;
2768 }
2769 Log(gc, task, stats) log;
2770 ResourceMark rm;
2771 LogStream ls(log.trace());
2772 outputStream* st = &ls;
2773
2774 print_taskqueue_stats_hdr(st);
2775
2776 TaskQueueStats totals;
2777 const uint n = num_task_queues();
2778 for (uint i = 0; i < n; ++i) {
2779 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2780 totals += task_queue(i)->stats;
2781 }
2782 st->print_raw("tot "); totals.print(st); st->cr();
2783
2784 DEBUG_ONLY(totals.verify());
2785 }
2786
2787 void G1CollectedHeap::reset_taskqueue_stats() {
2788 const uint n = num_task_queues();
2789 for (uint i = 0; i < n; ++i) {
2790 task_queue(i)->stats.reset();
2791 }
2792 }
2793 #endif // TASKQUEUE_STATS
2794
2795 void G1CollectedHeap::wait_for_root_region_scanning() {
2796 double scan_wait_start = os::elapsedTime();
2797 // We have to wait until the CM threads finish scanning the
2798 // root regions as it's the only way to ensure that all the
2799 // objects on them have been correctly scanned before we start
2800 // moving them during the GC.
2801 bool waited = _cm->root_regions()->wait_until_scan_finished();
2802 double wait_time_ms = 0.0;
2803 if (waited) {
2804 double scan_wait_end = os::elapsedTime();
2805 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2806 }
2807 g1_policy()->phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2808 }
2809
2810 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2811 private:
2812 G1HRPrinter* _hr_printer;
2813 public:
2814 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2815
2816 virtual bool do_heap_region(HeapRegion* r) {
2817 _hr_printer->cset(r);
2818 return false;
2819 }
2820 };
2821
2822 void G1CollectedHeap::start_new_collection_set() {
2823 collection_set()->start_incremental_building();
2824
2825 clear_cset_fast_test();
2826
2827 guarantee(_eden.length() == 0, "eden should have been cleared");
2828 g1_policy()->transfer_survivors_to_cset(survivor());
2829 }
2830
2831 bool
2832 G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2833 assert_at_safepoint_on_vm_thread();
2834 guarantee(!is_gc_active(), "collection is not reentrant");
2835
2836 if (GCLocker::check_active_before_gc()) {
2837 return false;
2838 }
2839
2840 _gc_timer_stw->register_gc_start();
2841
2842 GCIdMark gc_id_mark;
2843 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2844
2845 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2846 ResourceMark rm;
2847
2848 g1_policy()->note_gc_start();
2849
2850 wait_for_root_region_scanning();
2851
2852 print_heap_before_gc();
2853 print_heap_regions();
2854 trace_heap_before_gc(_gc_tracer_stw);
2855
2856 _verifier->verify_region_sets_optional();
2857 _verifier->verify_dirty_young_regions();
2858
2859 // We should not be doing initial mark unless the conc mark thread is running
2860 if (!_cm_thread->should_terminate()) {
2861 // This call will decide whether this pause is an initial-mark
2862 // pause. If it is, in_initial_mark_gc() will return true
2863 // for the duration of this pause.
2864 g1_policy()->decide_on_conc_mark_initiation();
2865 }
2866
2867 // We do not allow initial-mark to be piggy-backed on a mixed GC.
2868 assert(!collector_state()->in_initial_mark_gc() ||
2869 collector_state()->in_young_only_phase(), "sanity");
2870
2871 // We also do not allow mixed GCs during marking.
2872 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2873
2874 // Record whether this pause is an initial mark. When the current
2875 // thread has completed its logging output and it's safe to signal
2876 // the CM thread, the flag's value in the policy has been reset.
2877 bool should_start_conc_mark = collector_state()->in_initial_mark_gc();
2878
2879 // Inner scope for scope based logging, timers, and stats collection
2880 {
2881 EvacuationInfo evacuation_info;
2882
2883 if (collector_state()->in_initial_mark_gc()) {
2884 // We are about to start a marking cycle, so we increment the
2885 // full collection counter.
2886 increment_old_marking_cycles_started();
2887 _cm->gc_tracer_cm()->set_gc_cause(gc_cause());
2888 }
2889
2890 _gc_tracer_stw->report_yc_type(collector_state()->yc_type());
2891
2892 GCTraceCPUTime tcpu;
2893
2894 G1HeapVerifier::G1VerifyType verify_type;
2895 FormatBuffer<> gc_string("Pause Young ");
2896 if (collector_state()->in_initial_mark_gc()) {
2897 gc_string.append("(Concurrent Start)");
2898 verify_type = G1HeapVerifier::G1VerifyConcurrentStart;
2899 } else if (collector_state()->in_young_only_phase()) {
2900 if (collector_state()->in_young_gc_before_mixed()) {
2901 gc_string.append("(Prepare Mixed)");
2902 } else {
2903 gc_string.append("(Normal)");
2904 }
2905 verify_type = G1HeapVerifier::G1VerifyYoungNormal;
2906 } else {
2907 gc_string.append("(Mixed)");
2908 verify_type = G1HeapVerifier::G1VerifyMixed;
2909 }
2910 GCTraceTime(Info, gc) tm(gc_string, NULL, gc_cause(), true);
2911
2912 uint active_workers = AdaptiveSizePolicy::calc_active_workers(workers()->total_workers(),
2913 workers()->active_workers(),
2914 Threads::number_of_non_daemon_threads());
2915 active_workers = workers()->update_active_workers(active_workers);
2916 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2917
2918 G1MonitoringScope ms(g1mm(),
2919 false /* full_gc */,
2920 collector_state()->yc_type() == Mixed /* all_memory_pools_affected */);
2921
2922 G1HeapTransition heap_transition(this);
2923 size_t heap_used_bytes_before_gc = used();
2924
2925 // Don't dynamically change the number of GC threads this early. A value of
2926 // 0 is used to indicate serial work. When parallel work is done,
2927 // it will be set.
2928
2929 { // Call to jvmpi::post_class_unload_events must occur outside of active GC
2930 IsGCActiveMark x;
2931
2932 gc_prologue(false);
2933
2934 if (VerifyRememberedSets) {
2935 log_info(gc, verify)("[Verifying RemSets before GC]");
2936 VerifyRegionRemSetClosure v_cl;
2937 heap_region_iterate(&v_cl);
2938 }
2939
2940 _verifier->verify_before_gc(verify_type);
2941
2942 _verifier->check_bitmaps("GC Start");
2943
2944 #if COMPILER2_OR_JVMCI
2945 DerivedPointerTable::clear();
2946 #endif
2947
2948 // Please see comment in g1CollectedHeap.hpp and
2949 // G1CollectedHeap::ref_processing_init() to see how
2950 // reference processing currently works in G1.
2951
2952 // Enable discovery in the STW reference processor
2953 _ref_processor_stw->enable_discovery();
2954
2955 {
2956 // We want to temporarily turn off discovery by the
2957 // CM ref processor, if necessary, and turn it back on
2958 // on again later if we do. Using a scoped
2959 // NoRefDiscovery object will do this.
2960 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2961
2962 // Forget the current alloc region (we might even choose it to be part
2963 // of the collection set!).
2964 _allocator->release_mutator_alloc_region();
2965
2966 // This timing is only used by the ergonomics to handle our pause target.
2967 // It is unclear why this should not include the full pause. We will
2968 // investigate this in CR 7178365.
2969 //
2970 // Preserving the old comment here if that helps the investigation:
2971 //
2972 // The elapsed time induced by the start time below deliberately elides
2973 // the possible verification above.
2974 double sample_start_time_sec = os::elapsedTime();
2975
2976 g1_policy()->record_collection_pause_start(sample_start_time_sec);
2977
2978 if (collector_state()->in_initial_mark_gc()) {
2979 concurrent_mark()->pre_initial_mark();
2980 }
2981
2982 g1_policy()->finalize_collection_set(target_pause_time_ms, &_survivor);
2983
2984 evacuation_info.set_collectionset_regions(collection_set()->region_length());
2985
2986 // Make sure the remembered sets are up to date. This needs to be
2987 // done before register_humongous_regions_with_cset(), because the
2988 // remembered sets are used there to choose eager reclaim candidates.
2989 // If the remembered sets are not up to date we might miss some
2990 // entries that need to be handled.
2991 g1_rem_set()->cleanupHRRS();
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, workers()->active_workers(), collection_set()->young_region_length());
3010 pre_evacuate_collection_set();
3011
3012 // Actually do the work...
3013 evacuate_collection_set(&per_thread_states);
3014
3015 post_evacuate_collection_set(evacuation_info, &per_thread_states);
3016
3017 const size_t* surviving_young_words = per_thread_states.surviving_young_words();
3018 free_collection_set(&_collection_set, evacuation_info, surviving_young_words);
3019
3020 eagerly_reclaim_humongous_regions();
3021
3022 record_obj_copy_mem_stats();
3023 _survivor_evac_stats.adjust_desired_plab_sz();
3024 _old_evac_stats.adjust_desired_plab_sz();
3025
3026 double start = os::elapsedTime();
3027 start_new_collection_set();
3028 g1_policy()->phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
3029
3030 if (evacuation_failed()) {
3031 double recalculate_used_start = os::elapsedTime();
3032 set_used(recalculate_used());
3033 g1_policy()->phase_times()->record_evac_fail_recalc_used_time((os::elapsedTime() - recalculate_used_start) * 1000.0);
3034
3035 if (_archive_allocator != NULL) {
3036 _archive_allocator->clear_used();
3037 }
3038 for (uint i = 0; i < ParallelGCThreads; i++) {
3039 if (_evacuation_failed_info_array[i].has_failed()) {
3040 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
3041 }
3042 }
3043 } else {
3044 // The "used" of the the collection set have already been subtracted
3045 // when they were freed. Add in the bytes evacuated.
3046 increase_used(g1_policy()->bytes_copied_during_gc());
3047 }
3048
3049 if (collector_state()->in_initial_mark_gc()) {
3050 // We have to do this before we notify the CM threads that
3051 // they can start working to make sure that all the
3052 // appropriate initialization is done on the CM object.
3053 concurrent_mark()->post_initial_mark();
3054 // Note that we don't actually trigger the CM thread at
3055 // this point. We do that later when we're sure that
3056 // the current thread has completed its logging output.
3057 }
3058
3059 allocate_dummy_regions();
3060
3061 _allocator->init_mutator_alloc_region();
3062
3063 {
3064 size_t expand_bytes = _heap_sizing_policy->expansion_amount();
3065 if (expand_bytes > 0) {
3066 size_t bytes_before = capacity();
3067 // No need for an ergo logging here,
3068 // expansion_amount() does this when it returns a value > 0.
3069 double expand_ms;
3070 if (!expand(expand_bytes, _workers, &expand_ms)) {
3071 // We failed to expand the heap. Cannot do anything about it.
3072 }
3073 g1_policy()->phase_times()->record_expand_heap_time(expand_ms);
3074 }
3075 }
3076
3077 // We redo the verification but now wrt to the new CSet which
3078 // has just got initialized after the previous CSet was freed.
3079 _cm->verify_no_cset_oops();
3080
3081 // This timing is only used by the ergonomics to handle our pause target.
3082 // It is unclear why this should not include the full pause. We will
3083 // investigate this in CR 7178365.
3084 double sample_end_time_sec = os::elapsedTime();
3085 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3086 size_t total_cards_scanned = g1_policy()->phase_times()->sum_thread_work_items(G1GCPhaseTimes::ScanRS, G1GCPhaseTimes::ScanRSScannedCards);
3087 g1_policy()->record_collection_pause_end(pause_time_ms, total_cards_scanned, heap_used_bytes_before_gc);
3088
3089 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3090 evacuation_info.set_bytes_copied(g1_policy()->bytes_copied_during_gc());
3091
3092 if (VerifyRememberedSets) {
3093 log_info(gc, verify)("[Verifying RemSets after GC]");
3094 VerifyRegionRemSetClosure v_cl;
3095 heap_region_iterate(&v_cl);
3096 }
3097
3098 _verifier->verify_after_gc(verify_type);
3099 _verifier->check_bitmaps("GC End");
3100
3101 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
3102 _ref_processor_stw->verify_no_references_recorded();
3103
3104 // CM reference discovery will be re-enabled if necessary.
3105 }
3106
3107 #ifdef TRACESPINNING
3108 ParallelTaskTerminator::print_termination_counts();
3109 #endif
3110
3111 gc_epilogue(false);
3112 }
3113
3114 // Print the remainder of the GC log output.
3115 if (evacuation_failed()) {
3116 log_info(gc)("To-space exhausted");
3117 }
3118
3119 g1_policy()->print_phases();
3120 heap_transition.print();
3121
3122 // It is not yet to safe to tell the concurrent mark to
3123 // start as we have some optional output below. We don't want the
3124 // output from the concurrent mark thread interfering with this
3125 // logging output either.
3126
3127 _hrm->verify_optional();
3128 _verifier->verify_region_sets_optional();
3129
3130 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3131 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3132
3133 print_heap_after_gc();
3134 print_heap_regions();
3135 trace_heap_after_gc(_gc_tracer_stw);
3136
3137 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3138 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3139 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3140 // before any GC notifications are raised.
3141 g1mm()->update_sizes();
3142
3143 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
3144 _gc_tracer_stw->report_tenuring_threshold(_g1_policy->tenuring_threshold());
3145 _gc_timer_stw->register_gc_end();
3146 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(), _gc_timer_stw->time_partitions());
3147 }
3148 // It should now be safe to tell the concurrent mark thread to start
3149 // without its logging output interfering with the logging output
3150 // that came from the pause.
3151
3152 if (should_start_conc_mark) {
3153 // CAUTION: after the doConcurrentMark() call below,
3154 // the concurrent marking thread(s) could be running
3155 // concurrently with us. Make sure that anything after
3156 // this point does not assume that we are the only GC thread
3157 // running. Note: of course, the actual marking work will
3158 // not start until the safepoint itself is released in
3159 // SuspendibleThreadSet::desynchronize().
3160 do_concurrent_mark();
3161 }
3162
3163 return true;
3164 }
3165
3166 void G1CollectedHeap::remove_self_forwarding_pointers() {
3167 G1ParRemoveSelfForwardPtrsTask rsfp_task;
3168 workers()->run_task(&rsfp_task);
3169 }
3170
3171 void G1CollectedHeap::restore_after_evac_failure() {
3172 double remove_self_forwards_start = os::elapsedTime();
3173
3174 remove_self_forwarding_pointers();
3175 SharedRestorePreservedMarksTaskExecutor task_executor(workers());
3176 _preserved_marks_set.restore(&task_executor);
3177
3178 g1_policy()->phase_times()->record_evac_fail_remove_self_forwards((os::elapsedTime() - remove_self_forwards_start) * 1000.0);
3179 }
3180
3181 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markOop m) {
3182 if (!_evacuation_failed) {
3183 _evacuation_failed = true;
3184 }
3185
3186 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3187 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3188 }
3189
3190 bool G1ParEvacuateFollowersClosure::offer_termination() {
3191 EventGCPhaseParallel event;
3192 G1ParScanThreadState* const pss = par_scan_state();
3193 start_term_time();
3194 const bool res = terminator()->offer_termination();
3195 end_term_time();
3196 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3197 return res;
3198 }
3199
3200 void G1ParEvacuateFollowersClosure::do_void() {
3201 EventGCPhaseParallel event;
3202 G1ParScanThreadState* const pss = par_scan_state();
3203 pss->trim_queue();
3204 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3205 do {
3206 EventGCPhaseParallel event;
3207 pss->steal_and_trim_queue(queues());
3208 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::ObjCopy));
3209 } while (!offer_termination());
3210 }
3211
3212 class G1ParTask : public AbstractGangTask {
3213 protected:
3214 G1CollectedHeap* _g1h;
3215 G1ParScanThreadStateSet* _pss;
3216 RefToScanQueueSet* _queues;
3217 G1RootProcessor* _root_processor;
3218 ParallelTaskTerminator _terminator;
3219 uint _n_workers;
3220
3221 public:
3222 G1ParTask(G1CollectedHeap* g1h, G1ParScanThreadStateSet* per_thread_states, RefToScanQueueSet *task_queues, G1RootProcessor* root_processor, uint n_workers)
3223 : AbstractGangTask("G1 collection"),
3224 _g1h(g1h),
3225 _pss(per_thread_states),
3226 _queues(task_queues),
3227 _root_processor(root_processor),
3228 _terminator(n_workers, _queues),
3229 _n_workers(n_workers)
3230 {}
3231
3232 void work(uint worker_id) {
3233 if (worker_id >= _n_workers) return; // no work needed this round
3234
3235 double start_sec = os::elapsedTime();
3236 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, start_sec);
3237
3238 {
3239 ResourceMark rm;
3240 HandleMark hm;
3241
3242 ReferenceProcessor* rp = _g1h->ref_processor_stw();
3243
3244 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3245 pss->set_ref_discoverer(rp);
3246
3247 double start_strong_roots_sec = os::elapsedTime();
3248
3249 _root_processor->evacuate_roots(pss, worker_id);
3250
3251 // We pass a weak code blobs closure to the remembered set scanning because we want to avoid
3252 // treating the nmethods visited to act as roots for concurrent marking.
3253 // We only want to make sure that the oops in the nmethods are adjusted with regard to the
3254 // objects copied by the current evacuation.
3255 _g1h->g1_rem_set()->oops_into_collection_set_do(pss, worker_id);
3256
3257 double strong_roots_sec = os::elapsedTime() - start_strong_roots_sec;
3258
3259 double term_sec = 0.0;
3260 size_t evac_term_attempts = 0;
3261 {
3262 double start = os::elapsedTime();
3263 G1ParEvacuateFollowersClosure evac(_g1h, pss, _queues, &_terminator);
3264 evac.do_void();
3265
3266 evac_term_attempts = evac.term_attempts();
3267 term_sec = evac.term_time();
3268 double elapsed_sec = os::elapsedTime() - start;
3269
3270 G1GCPhaseTimes* p = _g1h->g1_policy()->phase_times();
3271 p->add_time_secs(G1GCPhaseTimes::ObjCopy, worker_id, elapsed_sec - term_sec);
3272 p->record_time_secs(G1GCPhaseTimes::Termination, worker_id, term_sec);
3273 p->record_thread_work_item(G1GCPhaseTimes::Termination, worker_id, evac_term_attempts);
3274 }
3275
3276 assert(pss->queue_is_empty(), "should be empty");
3277
3278 if (log_is_enabled(Debug, gc, task, stats)) {
3279 MutexLockerEx x(ParGCRareEvent_lock, Mutex::_no_safepoint_check_flag);
3280 size_t lab_waste;
3281 size_t lab_undo_waste;
3282 pss->waste(lab_waste, lab_undo_waste);
3283 _g1h->print_termination_stats(worker_id,
3284 (os::elapsedTime() - start_sec) * 1000.0, /* elapsed time */
3285 strong_roots_sec * 1000.0, /* strong roots time */
3286 term_sec * 1000.0, /* evac term time */
3287 evac_term_attempts, /* evac term attempts */
3288 lab_waste, /* alloc buffer waste */
3289 lab_undo_waste /* undo waste */
3290 );
3291 }
3292
3293 // Close the inner scope so that the ResourceMark and HandleMark
3294 // destructors are executed here and are included as part of the
3295 // "GC Worker Time".
3296 }
3297 _g1h->g1_policy()->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, os::elapsedTime());
3298 }
3299 };
3300
3301 void G1CollectedHeap::print_termination_stats_hdr() {
3302 log_debug(gc, task, stats)("GC Termination Stats");
3303 log_debug(gc, task, stats)(" elapsed --strong roots-- -------termination------- ------waste (KiB)------");
3304 log_debug(gc, task, stats)("thr ms ms %% ms %% attempts total alloc undo");
3305 log_debug(gc, task, stats)("--- --------- --------- ------ --------- ------ -------- ------- ------- -------");
3306 }
3307
3308 void G1CollectedHeap::print_termination_stats(uint worker_id,
3309 double elapsed_ms,
3310 double strong_roots_ms,
3311 double term_ms,
3312 size_t term_attempts,
3313 size_t alloc_buffer_waste,
3314 size_t undo_waste) const {
3315 log_debug(gc, task, stats)
3316 ("%3d %9.2f %9.2f %6.2f "
3317 "%9.2f %6.2f " SIZE_FORMAT_W(8) " "
3318 SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7) " " SIZE_FORMAT_W(7),
3319 worker_id, elapsed_ms, strong_roots_ms, strong_roots_ms * 100 / elapsed_ms,
3320 term_ms, term_ms * 100 / elapsed_ms, term_attempts,
3321 (alloc_buffer_waste + undo_waste) * HeapWordSize / K,
3322 alloc_buffer_waste * HeapWordSize / K,
3323 undo_waste * HeapWordSize / K);
3324 }
3325
3326 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3327 bool class_unloading_occurred) {
3328 uint n_workers = workers()->active_workers();
3329
3330 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3331 ParallelCleaningTask g1_unlink_task(is_alive, &dedup_closure, n_workers, class_unloading_occurred);
3332 workers()->run_task(&g1_unlink_task);
3333 }
3334
3335 void G1CollectedHeap::partial_cleaning(BoolObjectClosure* is_alive,
3336 bool process_strings,
3337 bool process_string_dedup) {
3338 if (!process_strings && !process_string_dedup) {
3339 // Nothing to clean.
3340 return;
3341 }
3342
3343 G1StringDedupUnlinkOrOopsDoClosure dedup_closure(is_alive, NULL, false);
3344 StringCleaningTask g1_unlink_task(is_alive, process_string_dedup ? &dedup_closure : NULL, process_strings);
3345 workers()->run_task(&g1_unlink_task);
3346 }
3347
3348 class G1RedirtyLoggedCardsTask : public AbstractGangTask {
3349 private:
3350 DirtyCardQueueSet* _queue;
3351 G1CollectedHeap* _g1h;
3352 public:
3353 G1RedirtyLoggedCardsTask(DirtyCardQueueSet* queue, G1CollectedHeap* g1h) : AbstractGangTask("Redirty Cards"),
3354 _queue(queue), _g1h(g1h) { }
3355
3356 virtual void work(uint worker_id) {
3357 G1GCPhaseTimes* phase_times = _g1h->g1_policy()->phase_times();
3358 G1GCParPhaseTimesTracker x(phase_times, G1GCPhaseTimes::RedirtyCards, worker_id);
3359
3360 RedirtyLoggedCardTableEntryClosure cl(_g1h);
3361 _queue->par_apply_closure_to_all_completed_buffers(&cl);
3362
3363 phase_times->record_thread_work_item(G1GCPhaseTimes::RedirtyCards, worker_id, cl.num_dirtied());
3364 }
3365 };
3366
3367 void G1CollectedHeap::redirty_logged_cards() {
3368 double redirty_logged_cards_start = os::elapsedTime();
3369
3370 G1RedirtyLoggedCardsTask redirty_task(&dirty_card_queue_set(), this);
3371 dirty_card_queue_set().reset_for_par_iteration();
3372 workers()->run_task(&redirty_task);
3373
3374 DirtyCardQueueSet& dcq = G1BarrierSet::dirty_card_queue_set();
3375 dcq.merge_bufferlists(&dirty_card_queue_set());
3376 assert(dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
3377
3378 g1_policy()->phase_times()->record_redirty_logged_cards_time_ms((os::elapsedTime() - redirty_logged_cards_start) * 1000.0);
3379 }
3380
3381 // Weak Reference Processing support
3382
3383 bool G1STWIsAliveClosure::do_object_b(oop p) {
3384 // An object is reachable if it is outside the collection set,
3385 // or is inside and copied.
3386 return !_g1h->is_in_cset(p) || p->is_forwarded();
3387 }
3388
3389 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3390 assert(obj != NULL, "must not be NULL");
3391 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3392 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3393 // may falsely indicate that this is not the case here: however the collection set only
3394 // contains old regions when concurrent mark is not running.
3395 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3396 }
3397
3398 // Non Copying Keep Alive closure
3399 class G1KeepAliveClosure: public OopClosure {
3400 G1CollectedHeap*_g1h;
3401 public:
3402 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3403 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3404 void do_oop(oop* p) {
3405 oop obj = *p;
3406 assert(obj != NULL, "the caller should have filtered out NULL values");
3407
3408 const InCSetState cset_state =_g1h->in_cset_state(obj);
3409 if (!cset_state.is_in_cset_or_humongous()) {
3410 return;
3411 }
3412 if (cset_state.is_in_cset()) {
3413 assert( obj->is_forwarded(), "invariant" );
3414 *p = obj->forwardee();
3415 } else {
3416 assert(!obj->is_forwarded(), "invariant" );
3417 assert(cset_state.is_humongous(),
3418 "Only allowed InCSet state is IsHumongous, but is %d", cset_state.value());
3419 _g1h->set_humongous_is_live(obj);
3420 }
3421 }
3422 };
3423
3424 // Copying Keep Alive closure - can be called from both
3425 // serial and parallel code as long as different worker
3426 // threads utilize different G1ParScanThreadState instances
3427 // and different queues.
3428
3429 class G1CopyingKeepAliveClosure: public OopClosure {
3430 G1CollectedHeap* _g1h;
3431 G1ParScanThreadState* _par_scan_state;
3432
3433 public:
3434 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3435 G1ParScanThreadState* pss):
3436 _g1h(g1h),
3437 _par_scan_state(pss)
3438 {}
3439
3440 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3441 virtual void do_oop( oop* p) { do_oop_work(p); }
3442
3443 template <class T> void do_oop_work(T* p) {
3444 oop obj = RawAccess<>::oop_load(p);
3445
3446 if (_g1h->is_in_cset_or_humongous(obj)) {
3447 // If the referent object has been forwarded (either copied
3448 // to a new location or to itself in the event of an
3449 // evacuation failure) then we need to update the reference
3450 // field and, if both reference and referent are in the G1
3451 // heap, update the RSet for the referent.
3452 //
3453 // If the referent has not been forwarded then we have to keep
3454 // it alive by policy. Therefore we have copy the referent.
3455 //
3456 // When the queue is drained (after each phase of reference processing)
3457 // the object and it's followers will be copied, the reference field set
3458 // to point to the new location, and the RSet updated.
3459 _par_scan_state->push_on_queue(p);
3460 }
3461 }
3462 };
3463
3464 // Serial drain queue closure. Called as the 'complete_gc'
3465 // closure for each discovered list in some of the
3466 // reference processing phases.
3467
3468 class G1STWDrainQueueClosure: public VoidClosure {
3469 protected:
3470 G1CollectedHeap* _g1h;
3471 G1ParScanThreadState* _par_scan_state;
3472
3473 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3474
3475 public:
3476 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3477 _g1h(g1h),
3478 _par_scan_state(pss)
3479 { }
3480
3481 void do_void() {
3482 G1ParScanThreadState* const pss = par_scan_state();
3483 pss->trim_queue();
3484 }
3485 };
3486
3487 // Parallel Reference Processing closures
3488
3489 // Implementation of AbstractRefProcTaskExecutor for parallel reference
3490 // processing during G1 evacuation pauses.
3491
3492 class G1STWRefProcTaskExecutor: public AbstractRefProcTaskExecutor {
3493 private:
3494 G1CollectedHeap* _g1h;
3495 G1ParScanThreadStateSet* _pss;
3496 RefToScanQueueSet* _queues;
3497 WorkGang* _workers;
3498
3499 public:
3500 G1STWRefProcTaskExecutor(G1CollectedHeap* g1h,
3501 G1ParScanThreadStateSet* per_thread_states,
3502 WorkGang* workers,
3503 RefToScanQueueSet *task_queues) :
3504 _g1h(g1h),
3505 _pss(per_thread_states),
3506 _queues(task_queues),
3507 _workers(workers)
3508 {
3509 g1h->ref_processor_stw()->set_active_mt_degree(workers->active_workers());
3510 }
3511
3512 // Executes the given task using concurrent marking worker threads.
3513 virtual void execute(ProcessTask& task, uint ergo_workers);
3514 };
3515
3516 // Gang task for possibly parallel reference processing
3517
3518 class G1STWRefProcTaskProxy: public AbstractGangTask {
3519 typedef AbstractRefProcTaskExecutor::ProcessTask ProcessTask;
3520 ProcessTask& _proc_task;
3521 G1CollectedHeap* _g1h;
3522 G1ParScanThreadStateSet* _pss;
3523 RefToScanQueueSet* _task_queues;
3524 ParallelTaskTerminator* _terminator;
3525
3526 public:
3527 G1STWRefProcTaskProxy(ProcessTask& proc_task,
3528 G1CollectedHeap* g1h,
3529 G1ParScanThreadStateSet* per_thread_states,
3530 RefToScanQueueSet *task_queues,
3531 ParallelTaskTerminator* terminator) :
3532 AbstractGangTask("Process reference objects in parallel"),
3533 _proc_task(proc_task),
3534 _g1h(g1h),
3535 _pss(per_thread_states),
3536 _task_queues(task_queues),
3537 _terminator(terminator)
3538 {}
3539
3540 virtual void work(uint worker_id) {
3541 // The reference processing task executed by a single worker.
3542 ResourceMark rm;
3543 HandleMark hm;
3544
3545 G1STWIsAliveClosure is_alive(_g1h);
3546
3547 G1ParScanThreadState* pss = _pss->state_for_worker(worker_id);
3548 pss->set_ref_discoverer(NULL);
3549
3550 // Keep alive closure.
3551 G1CopyingKeepAliveClosure keep_alive(_g1h, pss);
3552
3553 // Complete GC closure
3554 G1ParEvacuateFollowersClosure drain_queue(_g1h, pss, _task_queues, _terminator);
3555
3556 // Call the reference processing task's work routine.
3557 _proc_task.work(worker_id, is_alive, keep_alive, drain_queue);
3558
3559 // Note we cannot assert that the refs array is empty here as not all
3560 // of the processing tasks (specifically phase2 - pp2_work) execute
3561 // the complete_gc closure (which ordinarily would drain the queue) so
3562 // the queue may not be empty.
3563 }
3564 };
3565
3566 // Driver routine for parallel reference processing.
3567 // Creates an instance of the ref processing gang
3568 // task and has the worker threads execute it.
3569 void G1STWRefProcTaskExecutor::execute(ProcessTask& proc_task, uint ergo_workers) {
3570 assert(_workers != NULL, "Need parallel worker threads.");
3571
3572 assert(_workers->active_workers() >= ergo_workers,
3573 "Ergonomically chosen workers (%u) should be less than or equal to active workers (%u)",
3574 ergo_workers, _workers->active_workers());
3575 ParallelTaskTerminator terminator(ergo_workers, _queues);
3576 G1STWRefProcTaskProxy proc_task_proxy(proc_task, _g1h, _pss, _queues, &terminator);
3577
3578 _workers->run_task(&proc_task_proxy, ergo_workers);
3579 }
3580
3581 // End of weak reference support closures
3582
3583 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3584 double ref_proc_start = os::elapsedTime();
3585
3586 ReferenceProcessor* rp = _ref_processor_stw;
3587 assert(rp->discovery_enabled(), "should have been enabled");
3588
3589 // Closure to test whether a referent is alive.
3590 G1STWIsAliveClosure is_alive(this);
3591
3592 // Even when parallel reference processing is enabled, the processing
3593 // of JNI refs is serial and performed serially by the current thread
3594 // rather than by a worker. The following PSS will be used for processing
3595 // JNI refs.
3596
3597 // Use only a single queue for this PSS.
3598 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3599 pss->set_ref_discoverer(NULL);
3600 assert(pss->queue_is_empty(), "pre-condition");
3601
3602 // Keep alive closure.
3603 G1CopyingKeepAliveClosure keep_alive(this, pss);
3604
3605 // Serial Complete GC closure
3606 G1STWDrainQueueClosure drain_queue(this, pss);
3607
3608 // Setup the soft refs policy...
3609 rp->setup_policy(false);
3610
3611 ReferenceProcessorPhaseTimes* pt = g1_policy()->phase_times()->ref_phase_times();
3612
3613 ReferenceProcessorStats stats;
3614 if (!rp->processing_is_mt()) {
3615 // Serial reference processing...
3616 stats = rp->process_discovered_references(&is_alive,
3617 &keep_alive,
3618 &drain_queue,
3619 NULL,
3620 pt);
3621 } else {
3622 uint no_of_gc_workers = workers()->active_workers();
3623
3624 // Parallel reference processing
3625 assert(no_of_gc_workers <= rp->max_num_queues(),
3626 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3627 no_of_gc_workers, rp->max_num_queues());
3628
3629 G1STWRefProcTaskExecutor par_task_executor(this, per_thread_states, workers(), _task_queues);
3630 stats = rp->process_discovered_references(&is_alive,
3631 &keep_alive,
3632 &drain_queue,
3633 &par_task_executor,
3634 pt);
3635 }
3636
3637 _gc_tracer_stw->report_gc_reference_stats(stats);
3638
3639 // We have completed copying any necessary live referent objects.
3640 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3641
3642 make_pending_list_reachable();
3643
3644 rp->verify_no_references_recorded();
3645
3646 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3647 g1_policy()->phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3648 }
3649
3650 void G1CollectedHeap::make_pending_list_reachable() {
3651 if (collector_state()->in_initial_mark_gc()) {
3652 oop pll_head = Universe::reference_pending_list();
3653 if (pll_head != NULL) {
3654 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3655 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3656 }
3657 }
3658 }
3659
3660 void G1CollectedHeap::merge_per_thread_state_info(G1ParScanThreadStateSet* per_thread_states) {
3661 double merge_pss_time_start = os::elapsedTime();
3662 per_thread_states->flush();
3663 g1_policy()->phase_times()->record_merge_pss_time_ms((os::elapsedTime() - merge_pss_time_start) * 1000.0);
3664 }
3665
3666 void G1CollectedHeap::pre_evacuate_collection_set() {
3667 _expand_heap_after_alloc_failure = true;
3668 _evacuation_failed = false;
3669
3670 // Disable the hot card cache.
3671 _hot_card_cache->reset_hot_cache_claimed_index();
3672 _hot_card_cache->set_use_cache(false);
3673
3674 g1_rem_set()->prepare_for_oops_into_collection_set_do();
3675 _preserved_marks_set.assert_empty();
3676
3677 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3678
3679 // InitialMark needs claim bits to keep track of the marked-through CLDs.
3680 if (collector_state()->in_initial_mark_gc()) {
3681 double start_clear_claimed_marks = os::elapsedTime();
3682
3683 ClassLoaderDataGraph::clear_claimed_marks();
3684
3685 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3686 phase_times->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3687 }
3688 }
3689
3690 void G1CollectedHeap::evacuate_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3691 // Should G1EvacuationFailureALot be in effect for this GC?
3692 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3693
3694 assert(dirty_card_queue_set().completed_buffers_num() == 0, "Should be empty");
3695
3696 G1GCPhaseTimes* phase_times = g1_policy()->phase_times();
3697
3698 double start_par_time_sec = os::elapsedTime();
3699 double end_par_time_sec;
3700
3701 {
3702 const uint n_workers = workers()->active_workers();
3703 G1RootProcessor root_processor(this, n_workers);
3704 G1ParTask g1_par_task(this, per_thread_states, _task_queues, &root_processor, n_workers);
3705
3706 print_termination_stats_hdr();
3707
3708 workers()->run_task(&g1_par_task);
3709 end_par_time_sec = os::elapsedTime();
3710
3711 // Closing the inner scope will execute the destructor
3712 // for the G1RootProcessor object. We record the current
3713 // elapsed time before closing the scope so that time
3714 // taken for the destructor is NOT included in the
3715 // reported parallel time.
3716 }
3717
3718 double par_time_ms = (end_par_time_sec - start_par_time_sec) * 1000.0;
3719 phase_times->record_par_time(par_time_ms);
3720
3721 double code_root_fixup_time_ms =
3722 (os::elapsedTime() - end_par_time_sec) * 1000.0;
3723 phase_times->record_code_root_fixup_time(code_root_fixup_time_ms);
3724 }
3725
3726 void G1CollectedHeap::post_evacuate_collection_set(EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3727 // Also cleans the card table from temporary duplicate detection information used
3728 // during UpdateRS/ScanRS.
3729 g1_rem_set()->cleanup_after_oops_into_collection_set_do();
3730
3731 // Process any discovered reference objects - we have
3732 // to do this _before_ we retire the GC alloc regions
3733 // as we may have to copy some 'reachable' referent
3734 // objects (and their reachable sub-graphs) that were
3735 // not copied during the pause.
3736 process_discovered_references(per_thread_states);
3737
3738 // FIXME
3739 // CM's reference processing also cleans up the string table.
3740 // Should we do that here also? We could, but it is a serial operation
3741 // and could significantly increase the pause time.
3742
3743 G1STWIsAliveClosure is_alive(this);
3744 G1KeepAliveClosure keep_alive(this);
3745
3746 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive,
3747 g1_policy()->phase_times()->weak_phase_times());
3748
3749 if (G1StringDedup::is_enabled()) {
3750 double fixup_start = os::elapsedTime();
3751
3752 G1StringDedup::unlink_or_oops_do(&is_alive, &keep_alive, true, g1_policy()->phase_times());
3753
3754 double fixup_time_ms = (os::elapsedTime() - fixup_start) * 1000.0;
3755 g1_policy()->phase_times()->record_string_dedup_fixup_time(fixup_time_ms);
3756 }
3757
3758 if (evacuation_failed()) {
3759 restore_after_evac_failure();
3760
3761 // Reset the G1EvacuationFailureALot counters and flags
3762 // Note: the values are reset only when an actual
3763 // evacuation failure occurs.
3764 NOT_PRODUCT(reset_evacuation_should_fail();)
3765 }
3766
3767 _preserved_marks_set.assert_empty();
3768
3769 _allocator->release_gc_alloc_regions(evacuation_info);
3770
3771 merge_per_thread_state_info(per_thread_states);
3772
3773 // Reset and re-enable the hot card cache.
3774 // Note the counts for the cards in the regions in the
3775 // collection set are reset when the collection set is freed.
3776 _hot_card_cache->reset_hot_cache();
3777 _hot_card_cache->set_use_cache(true);
3778
3779 purge_code_root_memory();
3780
3781 redirty_logged_cards();
3782 #if COMPILER2_OR_JVMCI
3783 double start = os::elapsedTime();
3784 DerivedPointerTable::update_pointers();
3785 g1_policy()->phase_times()->record_derived_pointer_table_update_time((os::elapsedTime() - start) * 1000.0);
3786 #endif
3787 g1_policy()->print_age_table();
3788 }
3789
3790 void G1CollectedHeap::record_obj_copy_mem_stats() {
3791 g1_policy()->add_bytes_allocated_in_old_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3792
3793 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3794 create_g1_evac_summary(&_old_evac_stats));
3795 }
3796
3797 void G1CollectedHeap::free_region(HeapRegion* hr,
3798 FreeRegionList* free_list,
3799 bool skip_remset,
3800 bool skip_hot_card_cache,
3801 bool locked) {
3802 assert(!hr->is_free(), "the region should not be free");
3803 assert(!hr->is_empty(), "the region should not be empty");
3804 assert(_hrm->is_available(hr->hrm_index()), "region should be committed");
3805 assert(free_list != NULL, "pre-condition");
3806
3807 if (G1VerifyBitmaps) {
3808 MemRegion mr(hr->bottom(), hr->end());
3809 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3810 }
3811
3812 // Clear the card counts for this region.
3813 // Note: we only need to do this if the region is not young
3814 // (since we don't refine cards in young regions).
3815 if (!skip_hot_card_cache && !hr->is_young()) {
3816 _hot_card_cache->reset_card_counts(hr);
3817 }
3818 hr->hr_clear(skip_remset, true /* clear_space */, locked /* locked */);
3819 _g1_policy->remset_tracker()->update_at_free(hr);
3820 free_list->add_ordered(hr);
3821 }
3822
3823 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3824 FreeRegionList* free_list) {
3825 assert(hr->is_humongous(), "this is only for humongous regions");
3826 assert(free_list != NULL, "pre-condition");
3827 hr->clear_humongous();
3828 free_region(hr, free_list, false /* skip_remset */, false /* skip_hcc */, true /* locked */);
3829 }
3830
3831 void G1CollectedHeap::remove_from_old_sets(const uint old_regions_removed,
3832 const uint humongous_regions_removed) {
3833 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
3834 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3835 _old_set.bulk_remove(old_regions_removed);
3836 _humongous_set.bulk_remove(humongous_regions_removed);
3837 }
3838
3839 }
3840
3841 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3842 assert(list != NULL, "list can't be null");
3843 if (!list->is_empty()) {
3844 MutexLockerEx x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3845 _hrm->insert_list_into_free_list(list);
3846 }
3847 }
3848
3849 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3850 decrease_used(bytes);
3851 }
3852
3853 class G1FreeCollectionSetTask : public AbstractGangTask {
3854 private:
3855
3856 // Closure applied to all regions in the collection set to do work that needs to
3857 // be done serially in a single thread.
3858 class G1SerialFreeCollectionSetClosure : public HeapRegionClosure {
3859 private:
3860 EvacuationInfo* _evacuation_info;
3861 const size_t* _surviving_young_words;
3862
3863 // Bytes used in successfully evacuated regions before the evacuation.
3864 size_t _before_used_bytes;
3865 // Bytes used in unsucessfully evacuated regions before the evacuation
3866 size_t _after_used_bytes;
3867
3868 size_t _bytes_allocated_in_old_since_last_gc;
3869
3870 size_t _failure_used_words;
3871 size_t _failure_waste_words;
3872
3873 FreeRegionList _local_free_list;
3874 public:
3875 G1SerialFreeCollectionSetClosure(EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
3876 HeapRegionClosure(),
3877 _evacuation_info(evacuation_info),
3878 _surviving_young_words(surviving_young_words),
3879 _before_used_bytes(0),
3880 _after_used_bytes(0),
3881 _bytes_allocated_in_old_since_last_gc(0),
3882 _failure_used_words(0),
3883 _failure_waste_words(0),
3884 _local_free_list("Local Region List for CSet Freeing") {
3885 }
3886
3887 virtual bool do_heap_region(HeapRegion* r) {
3888 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3889
3890 assert(r->in_collection_set(), "Region %u should be in collection set.", r->hrm_index());
3891 g1h->clear_in_cset(r);
3892
3893 if (r->is_young()) {
3894 assert(r->young_index_in_cset() != -1 && (uint)r->young_index_in_cset() < g1h->collection_set()->young_region_length(),
3895 "Young index %d is wrong for region %u of type %s with %u young regions",
3896 r->young_index_in_cset(),
3897 r->hrm_index(),
3898 r->get_type_str(),
3899 g1h->collection_set()->young_region_length());
3900 size_t words_survived = _surviving_young_words[r->young_index_in_cset()];
3901 r->record_surv_words_in_group(words_survived);
3902 }
3903
3904 if (!r->evacuation_failed()) {
3905 assert(r->not_empty(), "Region %u is an empty region in the collection set.", r->hrm_index());
3906 _before_used_bytes += r->used();
3907 g1h->free_region(r,
3908 &_local_free_list,
3909 true, /* skip_remset */
3910 true, /* skip_hot_card_cache */
3911 true /* locked */);
3912 } else {
3913 r->uninstall_surv_rate_group();
3914 r->set_young_index_in_cset(-1);
3915 r->set_evacuation_failed(false);
3916 // When moving a young gen region to old gen, we "allocate" that whole region
3917 // there. This is in addition to any already evacuated objects. Notify the
3918 // policy about that.
3919 // Old gen regions do not cause an additional allocation: both the objects
3920 // still in the region and the ones already moved are accounted for elsewhere.
3921 if (r->is_young()) {
3922 _bytes_allocated_in_old_since_last_gc += HeapRegion::GrainBytes;
3923 }
3924 // The region is now considered to be old.
3925 if(g1h->is_hetero_heap()) {
3926 if(!r->is_old()) {
3927 // The region was young before, set it as pre-matured old so that next mixed gc can move
3928 // its contents to old region which is on nv-dimm
3929 r->set_premature_old();
3930 }
3931 } else {
3932 r->set_old();
3933 }
3934 // Do some allocation statistics accounting. Regions that failed evacuation
3935 // are always made old, so there is no need to update anything in the young
3936 // gen statistics, but we need to update old gen statistics.
3937 size_t used_words = r->marked_bytes() / HeapWordSize;
3938
3939 _failure_used_words += used_words;
3940 _failure_waste_words += HeapRegion::GrainWords - used_words;
3941
3942 g1h->old_set_add(r);
3943 _after_used_bytes += r->used();
3944 }
3945 return false;
3946 }
3947
3948 void complete_work() {
3949 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3950
3951 _evacuation_info->set_regions_freed(_local_free_list.length());
3952 _evacuation_info->increment_collectionset_used_after(_after_used_bytes);
3953
3954 g1h->prepend_to_freelist(&_local_free_list);
3955 g1h->decrement_summary_bytes(_before_used_bytes);
3956
3957 G1Policy* policy = g1h->g1_policy();
3958 policy->add_bytes_allocated_in_old_since_last_gc(_bytes_allocated_in_old_since_last_gc);
3959
3960 g1h->alloc_buffer_stats(InCSetState::Old)->add_failure_used_and_waste(_failure_used_words, _failure_waste_words);
3961 }
3962 };
3963
3964 G1CollectionSet* _collection_set;
3965 G1SerialFreeCollectionSetClosure _cl;
3966 const size_t* _surviving_young_words;
3967
3968 size_t _rs_lengths;
3969
3970 volatile jint _serial_work_claim;
3971
3972 struct WorkItem {
3973 uint region_idx;
3974 bool is_young;
3975 bool evacuation_failed;
3976
3977 WorkItem(HeapRegion* r) {
3978 region_idx = r->hrm_index();
3979 is_young = r->is_young();
3980 evacuation_failed = r->evacuation_failed();
3981 }
3982 };
3983
3984 volatile size_t _parallel_work_claim;
3985 size_t _num_work_items;
3986 WorkItem* _work_items;
3987
3988 void do_serial_work() {
3989 // Need to grab the lock to be allowed to modify the old region list.
3990 MutexLockerEx x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3991 _collection_set->iterate(&_cl);
3992 }
3993
3994 void do_parallel_work_for_region(uint region_idx, bool is_young, bool evacuation_failed) {
3995 G1CollectedHeap* g1h = G1CollectedHeap::heap();
3996
3997 HeapRegion* r = g1h->region_at(region_idx);
3998 assert(!g1h->is_on_master_free_list(r), "sanity");
3999
4000 Atomic::add(r->rem_set()->occupied_locked(), &_rs_lengths);
4001
4002 if (!is_young) {
4003 g1h->_hot_card_cache->reset_card_counts(r);
4004 }
4005
4006 if (!evacuation_failed) {
4007 r->rem_set()->clear_locked();
4008 }
4009 }
4010
4011 class G1PrepareFreeCollectionSetClosure : public HeapRegionClosure {
4012 private:
4013 size_t _cur_idx;
4014 WorkItem* _work_items;
4015 public:
4016 G1PrepareFreeCollectionSetClosure(WorkItem* work_items) : HeapRegionClosure(), _cur_idx(0), _work_items(work_items) { }
4017
4018 virtual bool do_heap_region(HeapRegion* r) {
4019 _work_items[_cur_idx++] = WorkItem(r);
4020 return false;
4021 }
4022 };
4023
4024 void prepare_work() {
4025 G1PrepareFreeCollectionSetClosure cl(_work_items);
4026 _collection_set->iterate(&cl);
4027 }
4028
4029 void complete_work() {
4030 _cl.complete_work();
4031
4032 G1Policy* policy = G1CollectedHeap::heap()->g1_policy();
4033 policy->record_max_rs_lengths(_rs_lengths);
4034 policy->cset_regions_freed();
4035 }
4036 public:
4037 G1FreeCollectionSetTask(G1CollectionSet* collection_set, EvacuationInfo* evacuation_info, const size_t* surviving_young_words) :
4038 AbstractGangTask("G1 Free Collection Set"),
4039 _collection_set(collection_set),
4040 _cl(evacuation_info, surviving_young_words),
4041 _surviving_young_words(surviving_young_words),
4042 _rs_lengths(0),
4043 _serial_work_claim(0),
4044 _parallel_work_claim(0),
4045 _num_work_items(collection_set->region_length()),
4046 _work_items(NEW_C_HEAP_ARRAY(WorkItem, _num_work_items, mtGC)) {
4047 prepare_work();
4048 }
4049
4050 ~G1FreeCollectionSetTask() {
4051 complete_work();
4052 FREE_C_HEAP_ARRAY(WorkItem, _work_items);
4053 }
4054
4055 // Chunk size for work distribution. The chosen value has been determined experimentally
4056 // to be a good tradeoff between overhead and achievable parallelism.
4057 static uint chunk_size() { return 32; }
4058
4059 virtual void work(uint worker_id) {
4060 G1GCPhaseTimes* timer = G1CollectedHeap::heap()->g1_policy()->phase_times();
4061
4062 // Claim serial work.
4063 if (_serial_work_claim == 0) {
4064 jint value = Atomic::add(1, &_serial_work_claim) - 1;
4065 if (value == 0) {
4066 double serial_time = os::elapsedTime();
4067 do_serial_work();
4068 timer->record_serial_free_cset_time_ms((os::elapsedTime() - serial_time) * 1000.0);
4069 }
4070 }
4071
4072 // Start parallel work.
4073 double young_time = 0.0;
4074 bool has_young_time = false;
4075 double non_young_time = 0.0;
4076 bool has_non_young_time = false;
4077
4078 while (true) {
4079 size_t end = Atomic::add(chunk_size(), &_parallel_work_claim);
4080 size_t cur = end - chunk_size();
4081
4082 if (cur >= _num_work_items) {
4083 break;
4084 }
4085
4086 EventGCPhaseParallel event;
4087 double start_time = os::elapsedTime();
4088
4089 end = MIN2(end, _num_work_items);
4090
4091 for (; cur < end; cur++) {
4092 bool is_young = _work_items[cur].is_young;
4093
4094 do_parallel_work_for_region(_work_items[cur].region_idx, is_young, _work_items[cur].evacuation_failed);
4095
4096 double end_time = os::elapsedTime();
4097 double time_taken = end_time - start_time;
4098 if (is_young) {
4099 young_time += time_taken;
4100 has_young_time = true;
4101 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::YoungFreeCSet));
4102 } else {
4103 non_young_time += time_taken;
4104 has_non_young_time = true;
4105 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::NonYoungFreeCSet));
4106 }
4107 start_time = end_time;
4108 }
4109 }
4110
4111 if (has_young_time) {
4112 timer->record_time_secs(G1GCPhaseTimes::YoungFreeCSet, worker_id, young_time);
4113 }
4114 if (has_non_young_time) {
4115 timer->record_time_secs(G1GCPhaseTimes::NonYoungFreeCSet, worker_id, non_young_time);
4116 }
4117 }
4118 };
4119
4120 void G1CollectedHeap::free_collection_set(G1CollectionSet* collection_set, EvacuationInfo& evacuation_info, const size_t* surviving_young_words) {
4121 _eden.clear();
4122
4123 double free_cset_start_time = os::elapsedTime();
4124
4125 {
4126 uint const num_chunks = MAX2(_collection_set.region_length() / G1FreeCollectionSetTask::chunk_size(), 1U);
4127 uint const num_workers = MIN2(workers()->active_workers(), num_chunks);
4128
4129 G1FreeCollectionSetTask cl(collection_set, &evacuation_info, surviving_young_words);
4130
4131 log_debug(gc, ergo)("Running %s using %u workers for collection set length %u",
4132 cl.name(),
4133 num_workers,
4134 _collection_set.region_length());
4135 workers()->run_task(&cl, num_workers);
4136 }
4137 g1_policy()->phase_times()->record_total_free_cset_time_ms((os::elapsedTime() - free_cset_start_time) * 1000.0);
4138
4139 collection_set->clear();
4140 }
4141
4142 class G1FreeHumongousRegionClosure : public HeapRegionClosure {
4143 private:
4144 FreeRegionList* _free_region_list;
4145 HeapRegionSet* _proxy_set;
4146 uint _humongous_objects_reclaimed;
4147 uint _humongous_regions_reclaimed;
4148 size_t _freed_bytes;
4149 public:
4150
4151 G1FreeHumongousRegionClosure(FreeRegionList* free_region_list) :
4152 _free_region_list(free_region_list), _humongous_objects_reclaimed(0), _humongous_regions_reclaimed(0), _freed_bytes(0) {
4153 }
4154
4155 virtual bool do_heap_region(HeapRegion* r) {
4156 if (!r->is_starts_humongous()) {
4157 return false;
4158 }
4159
4160 G1CollectedHeap* g1h = G1CollectedHeap::heap();
4161
4162 oop obj = (oop)r->bottom();
4163 G1CMBitMap* next_bitmap = g1h->concurrent_mark()->next_mark_bitmap();
4164
4165 // The following checks whether the humongous object is live are sufficient.
4166 // The main additional check (in addition to having a reference from the roots
4167 // or the young gen) is whether the humongous object has a remembered set entry.
4168 //
4169 // A humongous object cannot be live if there is no remembered set for it
4170 // because:
4171 // - there can be no references from within humongous starts regions referencing
4172 // the object because we never allocate other objects into them.
4173 // (I.e. there are no intra-region references that may be missed by the
4174 // remembered set)
4175 // - as soon there is a remembered set entry to the humongous starts region
4176 // (i.e. it has "escaped" to an old object) this remembered set entry will stay
4177 // until the end of a concurrent mark.
4178 //
4179 // It is not required to check whether the object has been found dead by marking
4180 // or not, in fact it would prevent reclamation within a concurrent cycle, as
4181 // all objects allocated during that time are considered live.
4182 // SATB marking is even more conservative than the remembered set.
4183 // So if at this point in the collection there is no remembered set entry,
4184 // nobody has a reference to it.
4185 // At the start of collection we flush all refinement logs, and remembered sets
4186 // are completely up-to-date wrt to references to the humongous object.
4187 //
4188 // Other implementation considerations:
4189 // - never consider object arrays at this time because they would pose
4190 // considerable effort for cleaning up the the remembered sets. This is
4191 // required because stale remembered sets might reference locations that
4192 // are currently allocated into.
4193 uint region_idx = r->hrm_index();
4194 if (!g1h->is_humongous_reclaim_candidate(region_idx) ||
4195 !r->rem_set()->is_empty()) {
4196 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",
4197 region_idx,
4198 (size_t)obj->size() * HeapWordSize,
4199 p2i(r->bottom()),
4200 r->rem_set()->occupied(),
4201 r->rem_set()->strong_code_roots_list_length(),
4202 next_bitmap->is_marked(r->bottom()),
4203 g1h->is_humongous_reclaim_candidate(region_idx),
4204 obj->is_typeArray()
4205 );
4206 return false;
4207 }
4208
4209 guarantee(obj->is_typeArray(),
4210 "Only eagerly reclaiming type arrays is supported, but the object "
4211 PTR_FORMAT " is not.", p2i(r->bottom()));
4212
4213 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",
4214 region_idx,
4215 (size_t)obj->size() * HeapWordSize,
4216 p2i(r->bottom()),
4217 r->rem_set()->occupied(),
4218 r->rem_set()->strong_code_roots_list_length(),
4219 next_bitmap->is_marked(r->bottom()),
4220 g1h->is_humongous_reclaim_candidate(region_idx),
4221 obj->is_typeArray()
4222 );
4223
4224 G1ConcurrentMark* const cm = g1h->concurrent_mark();
4225 cm->humongous_object_eagerly_reclaimed(r);
4226 assert(!cm->is_marked_in_prev_bitmap(obj) && !cm->is_marked_in_next_bitmap(obj),
4227 "Eagerly reclaimed humongous region %u should not be marked at all but is in prev %s next %s",
4228 region_idx,
4229 BOOL_TO_STR(cm->is_marked_in_prev_bitmap(obj)),
4230 BOOL_TO_STR(cm->is_marked_in_next_bitmap(obj)));
4231 _humongous_objects_reclaimed++;
4232 do {
4233 HeapRegion* next = g1h->next_region_in_humongous(r);
4234 _freed_bytes += r->used();
4235 r->set_containing_set(NULL);
4236 _humongous_regions_reclaimed++;
4237 g1h->free_humongous_region(r, _free_region_list);
4238 r = next;
4239 } while (r != NULL);
4240
4241 return false;
4242 }
4243
4244 uint humongous_objects_reclaimed() {
4245 return _humongous_objects_reclaimed;
4246 }
4247
4248 uint humongous_regions_reclaimed() {
4249 return _humongous_regions_reclaimed;
4250 }
4251
4252 size_t bytes_freed() const {
4253 return _freed_bytes;
4254 }
4255 };
4256
4257 void G1CollectedHeap::eagerly_reclaim_humongous_regions() {
4258 assert_at_safepoint_on_vm_thread();
4259
4260 if (!G1EagerReclaimHumongousObjects ||
4261 (!_has_humongous_reclaim_candidates && !log_is_enabled(Debug, gc, humongous))) {
4262 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms(0.0, 0);
4263 return;
4264 }
4265
4266 double start_time = os::elapsedTime();
4267
4268 FreeRegionList local_cleanup_list("Local Humongous Cleanup List");
4269
4270 G1FreeHumongousRegionClosure cl(&local_cleanup_list);
4271 heap_region_iterate(&cl);
4272
4273 remove_from_old_sets(0, cl.humongous_regions_reclaimed());
4274
4275 G1HRPrinter* hrp = hr_printer();
4276 if (hrp->is_active()) {
4277 FreeRegionListIterator iter(&local_cleanup_list);
4278 while (iter.more_available()) {
4279 HeapRegion* hr = iter.get_next();
4280 hrp->cleanup(hr);
4281 }
4282 }
4283
4284 prepend_to_freelist(&local_cleanup_list);
4285 decrement_summary_bytes(cl.bytes_freed());
4286
4287 g1_policy()->phase_times()->record_fast_reclaim_humongous_time_ms((os::elapsedTime() - start_time) * 1000.0,
4288 cl.humongous_objects_reclaimed());
4289 }
4290
4291 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
4292 public:
4293 virtual bool do_heap_region(HeapRegion* r) {
4294 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
4295 G1CollectedHeap::heap()->clear_in_cset(r);
4296 r->set_young_index_in_cset(-1);
4297 return false;
4298 }
4299 };
4300
4301 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
4302 G1AbandonCollectionSetClosure cl;
4303 collection_set->iterate(&cl);
4304
4305 collection_set->clear();
4306 collection_set->stop_incremental_building();
4307 }
4308
4309 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
4310 return _allocator->is_retained_old_region(hr);
4311 }
4312
4313 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
4314 _eden.add(hr);
4315 _g1_policy->set_region_eden(hr);
4316 }
4317
4318 #ifdef ASSERT
4319
4320 class NoYoungRegionsClosure: public HeapRegionClosure {
4321 private:
4322 bool _success;
4323 public:
4324 NoYoungRegionsClosure() : _success(true) { }
4325 bool do_heap_region(HeapRegion* r) {
4326 if (r->is_young()) {
4327 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
4328 p2i(r->bottom()), p2i(r->end()));
4329 _success = false;
4330 }
4331 return false;
4332 }
4333 bool success() { return _success; }
4334 };
4335
4336 bool G1CollectedHeap::check_young_list_empty() {
4337 bool ret = (young_regions_count() == 0);
4338
4339 NoYoungRegionsClosure closure;
4340 heap_region_iterate(&closure);
4341 ret = ret && closure.success();
4342
4343 return ret;
4344 }
4345
4346 #endif // ASSERT
4347
4348 class TearDownRegionSetsClosure : public HeapRegionClosure {
4349 HeapRegionSet *_old_set;
4350
4351 public:
4352 TearDownRegionSetsClosure(HeapRegionSet* old_set) : _old_set(old_set) { }
4353
4354 bool do_heap_region(HeapRegion* r) {
4355 if (r->is_old()) {
4356 _old_set->remove(r);
4357 } else if(r->is_young()) {
4358 r->uninstall_surv_rate_group();
4359 } else {
4360 // We ignore free regions, we'll empty the free list afterwards.
4361 // We ignore humongous and archive regions, we're not tearing down these
4362 // sets.
4363 assert(r->is_archive() || r->is_free() || r->is_humongous(),
4364 "it cannot be another type");
4365 }
4366 return false;
4367 }
4368
4369 ~TearDownRegionSetsClosure() {
4370 assert(_old_set->is_empty(), "post-condition");
4371 }
4372 };
4373
4374 void G1CollectedHeap::tear_down_region_sets(bool free_list_only) {
4375 assert_at_safepoint_on_vm_thread();
4376
4377 if (!free_list_only) {
4378 TearDownRegionSetsClosure cl(&_old_set);
4379 heap_region_iterate(&cl);
4380
4381 // Note that emptying the _young_list is postponed and instead done as
4382 // the first step when rebuilding the regions sets again. The reason for
4383 // this is that during a full GC string deduplication needs to know if
4384 // a collected region was young or old when the full GC was initiated.
4385 }
4386 _hrm->remove_all_free_regions();
4387 }
4388
4389 void G1CollectedHeap::increase_used(size_t bytes) {
4390 _summary_bytes_used += bytes;
4391 }
4392
4393 void G1CollectedHeap::decrease_used(size_t bytes) {
4394 assert(_summary_bytes_used >= bytes,
4395 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
4396 _summary_bytes_used, bytes);
4397 _summary_bytes_used -= bytes;
4398 }
4399
4400 void G1CollectedHeap::set_used(size_t bytes) {
4401 _summary_bytes_used = bytes;
4402 }
4403
4404 class RebuildRegionSetsClosure : public HeapRegionClosure {
4405 private:
4406 bool _free_list_only;
4407
4408 HeapRegionSet* _old_set;
4409 HeapRegionManager* _hrm;
4410
4411 size_t _total_used;
4412
4413 public:
4414 RebuildRegionSetsClosure(bool free_list_only,
4415 HeapRegionSet* old_set,
4416 HeapRegionManager* hrm) :
4417 _free_list_only(free_list_only),
4418 _old_set(old_set), _hrm(hrm), _total_used(0) {
4419 assert(_hrm->num_free_regions() == 0, "pre-condition");
4420 if (!free_list_only) {
4421 assert(_old_set->is_empty(), "pre-condition");
4422 }
4423 }
4424
4425 bool do_heap_region(HeapRegion* r) {
4426 // After full GC, no region should have a remembered set.
4427 r->rem_set()->clear(true);
4428 if (r->is_empty()) {
4429 // Add free regions to the free list
4430 r->set_free();
4431 _hrm->insert_into_free_list(r);
4432 } else if (!_free_list_only) {
4433
4434 if (r->is_archive() || r->is_humongous()) {
4435 // We ignore archive and humongous regions. We left these sets unchanged.
4436 } else {
4437 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4438 // We now move all (non-humongous, non-old, non-archive) regions to old gen, and register them as such.
4439 r->move_to_old();
4440 _old_set->add(r);
4441 }
4442 _total_used += r->used();
4443 }
4444
4445 return false;
4446 }
4447
4448 size_t total_used() {
4449 return _total_used;
4450 }
4451 };
4452
4453 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4454 assert_at_safepoint_on_vm_thread();
4455
4456 if (!free_list_only) {
4457 _eden.clear();
4458 _survivor.clear();
4459 }
4460
4461 RebuildRegionSetsClosure cl(free_list_only, &_old_set, _hrm);
4462 heap_region_iterate(&cl);
4463
4464 if (!free_list_only) {
4465 set_used(cl.total_used());
4466 if (_archive_allocator != NULL) {
4467 _archive_allocator->clear_used();
4468 }
4469 }
4470 assert(used_unlocked() == recalculate_used(),
4471 "inconsistent used_unlocked(), "
4472 "value: " SIZE_FORMAT " recalculated: " SIZE_FORMAT,
4473 used_unlocked(), recalculate_used());
4474 }
4475
4476 bool G1CollectedHeap::is_in_closed_subset(const void* p) const {
4477 HeapRegion* hr = heap_region_containing(p);
4478 return hr->is_in(p);
4479 }
4480
4481 // Methods for the mutator alloc region
4482
4483 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4484 bool force) {
4485 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4486 bool should_allocate = g1_policy()->should_allocate_mutator_region();
4487 if (force || should_allocate) {
4488 HeapRegion* new_alloc_region = new_region(word_size,
4489 false /* is_old */,
4490 false /* do_expand */);
4491 if (new_alloc_region != NULL) {
4492 set_region_short_lived_locked(new_alloc_region);
4493 _hr_printer.alloc(new_alloc_region, !should_allocate);
4494 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4495 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4496 return new_alloc_region;
4497 }
4498 }
4499 return NULL;
4500 }
4501
4502 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4503 size_t allocated_bytes) {
4504 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4505 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4506
4507 collection_set()->add_eden_region(alloc_region);
4508 increase_used(allocated_bytes);
4509 _hr_printer.retire(alloc_region);
4510 // We update the eden sizes here, when the region is retired,
4511 // instead of when it's allocated, since this is the point that its
4512 // used space has been recorded in _summary_bytes_used.
4513 g1mm()->update_eden_size();
4514 }
4515
4516 // Methods for the GC alloc regions
4517
4518 bool G1CollectedHeap::has_more_regions(InCSetState dest) {
4519 if (dest.is_old()) {
4520 return true;
4521 } else {
4522 return survivor_regions_count() < g1_policy()->max_survivor_regions();
4523 }
4524 }
4525
4526 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, InCSetState dest) {
4527 assert(FreeList_lock->owned_by_self(), "pre-condition");
4528
4529 if (!has_more_regions(dest)) {
4530 return NULL;
4531 }
4532
4533 const bool is_survivor = dest.is_young();
4534
4535 HeapRegion* new_alloc_region = new_region(word_size,
4536 !is_survivor,
4537 true /* do_expand */);
4538 if (new_alloc_region != NULL) {
4539 if (is_survivor) {
4540 new_alloc_region->set_survivor();
4541 _survivor.add(new_alloc_region);
4542 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4543 } else {
4544 new_alloc_region->set_old();
4545 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4546 }
4547 _g1_policy->remset_tracker()->update_at_allocate(new_alloc_region);
4548 _hr_printer.alloc(new_alloc_region);
4549 bool during_im = collector_state()->in_initial_mark_gc();
4550 new_alloc_region->note_start_of_copying(during_im);
4551 return new_alloc_region;
4552 }
4553 return NULL;
4554 }
4555
4556 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4557 size_t allocated_bytes,
4558 InCSetState dest) {
4559 bool during_im = collector_state()->in_initial_mark_gc();
4560 alloc_region->note_end_of_copying(during_im);
4561 g1_policy()->record_bytes_copied_during_gc(allocated_bytes);
4562 if (dest.is_old()) {
4563 old_set_add(alloc_region);
4564 }
4565 _hr_printer.retire(alloc_region);
4566 }
4567
4568 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4569 bool expanded = false;
4570 uint index = _hrm->find_highest_free(&expanded);
4571
4572 if (index != G1_NO_HRM_INDEX) {
4573 if (expanded) {
4574 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4575 HeapRegion::GrainWords * HeapWordSize);
4576 }
4577 _hrm->allocate_free_regions_starting_at(index, 1);
4578 return region_at(index);
4579 }
4580 return NULL;
4581 }
4582
4583 // Optimized nmethod scanning
4584
4585 class RegisterNMethodOopClosure: public OopClosure {
4586 G1CollectedHeap* _g1h;
4587 nmethod* _nm;
4588
4589 template <class T> void do_oop_work(T* p) {
4590 T heap_oop = RawAccess<>::oop_load(p);
4591 if (!CompressedOops::is_null(heap_oop)) {
4592 oop obj = CompressedOops::decode_not_null(heap_oop);
4593 HeapRegion* hr = _g1h->heap_region_containing(obj);
4594 assert(!hr->is_continues_humongous(),
4595 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4596 " starting at " HR_FORMAT,
4597 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4598
4599 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4600 hr->add_strong_code_root_locked(_nm);
4601 }
4602 }
4603
4604 public:
4605 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4606 _g1h(g1h), _nm(nm) {}
4607
4608 void do_oop(oop* p) { do_oop_work(p); }
4609 void do_oop(narrowOop* p) { do_oop_work(p); }
4610 };
4611
4612 class UnregisterNMethodOopClosure: public OopClosure {
4613 G1CollectedHeap* _g1h;
4614 nmethod* _nm;
4615
4616 template <class T> void do_oop_work(T* p) {
4617 T heap_oop = RawAccess<>::oop_load(p);
4618 if (!CompressedOops::is_null(heap_oop)) {
4619 oop obj = CompressedOops::decode_not_null(heap_oop);
4620 HeapRegion* hr = _g1h->heap_region_containing(obj);
4621 assert(!hr->is_continues_humongous(),
4622 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4623 " starting at " HR_FORMAT,
4624 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4625
4626 hr->remove_strong_code_root(_nm);
4627 }
4628 }
4629
4630 public:
4631 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4632 _g1h(g1h), _nm(nm) {}
4633
4634 void do_oop(oop* p) { do_oop_work(p); }
4635 void do_oop(narrowOop* p) { do_oop_work(p); }
4636 };
4637
4638 // Returns true if the reference points to an object that
4639 // can move in an incremental collection.
4640 bool G1CollectedHeap::is_scavengable(oop obj) {
4641 HeapRegion* hr = heap_region_containing(obj);
4642 return !hr->is_pinned();
4643 }
4644
4645 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4646 guarantee(nm != NULL, "sanity");
4647 RegisterNMethodOopClosure reg_cl(this, nm);
4648 nm->oops_do(®_cl);
4649 }
4650
4651 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4652 guarantee(nm != NULL, "sanity");
4653 UnregisterNMethodOopClosure reg_cl(this, nm);
4654 nm->oops_do(®_cl, true);
4655 }
4656
4657 void G1CollectedHeap::purge_code_root_memory() {
4658 double purge_start = os::elapsedTime();
4659 G1CodeRootSet::purge();
4660 double purge_time_ms = (os::elapsedTime() - purge_start) * 1000.0;
4661 g1_policy()->phase_times()->record_strong_code_root_purge_time(purge_time_ms);
4662 }
4663
4664 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4665 G1CollectedHeap* _g1h;
4666
4667 public:
4668 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4669 _g1h(g1h) {}
4670
4671 void do_code_blob(CodeBlob* cb) {
4672 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4673 if (nm == NULL) {
4674 return;
4675 }
4676
4677 if (ScavengeRootsInCode) {
4678 _g1h->register_nmethod(nm);
4679 }
4680 }
4681 };
4682
4683 void G1CollectedHeap::rebuild_strong_code_roots() {
4684 RebuildStrongCodeRootClosure blob_cl(this);
4685 CodeCache::blobs_do(&blob_cl);
4686 }
4687
4688 void G1CollectedHeap::initialize_serviceability() {
4689 _g1mm->initialize_serviceability();
4690 }
4691
4692 MemoryUsage G1CollectedHeap::memory_usage() {
4693 return _g1mm->memory_usage();
4694 }
4695
4696 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4697 return _g1mm->memory_managers();
4698 }
4699
4700 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4701 return _g1mm->memory_pools();
4702 }