1 /*
2 * Copyright (c) 2001, 2022, 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 "compiler/oopMap.hpp"
32 #include "gc/g1/g1Allocator.inline.hpp"
33 #include "gc/g1/g1Arguments.hpp"
34 #include "gc/g1/g1BarrierSet.hpp"
35 #include "gc/g1/g1BatchedTask.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectionSetCandidates.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1ConcurrentRefine.hpp"
41 #include "gc/g1/g1ConcurrentRefineThread.hpp"
42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
43 #include "gc/g1/g1DirtyCardQueue.hpp"
44 #include "gc/g1/g1EvacStats.inline.hpp"
45 #include "gc/g1/g1FullCollector.hpp"
46 #include "gc/g1/g1GCCounters.hpp"
47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
48 #include "gc/g1/g1GCPhaseTimes.hpp"
49 #include "gc/g1/g1GCPauseType.hpp"
50 #include "gc/g1/g1HeapSizingPolicy.hpp"
51 #include "gc/g1/g1HeapTransition.hpp"
52 #include "gc/g1/g1HeapVerifier.hpp"
53 #include "gc/g1/g1HotCardCache.hpp"
54 #include "gc/g1/g1InitLogger.hpp"
55 #include "gc/g1/g1MemoryPool.hpp"
56 #include "gc/g1/g1OopClosures.inline.hpp"
57 #include "gc/g1/g1ParallelCleaning.hpp"
58 #include "gc/g1/g1ParScanThreadState.inline.hpp"
59 #include "gc/g1/g1PeriodicGCTask.hpp"
60 #include "gc/g1/g1Policy.hpp"
61 #include "gc/g1/g1RedirtyCardsQueue.hpp"
62 #include "gc/g1/g1RegionToSpaceMapper.hpp"
63 #include "gc/g1/g1RemSet.hpp"
64 #include "gc/g1/g1RootClosures.hpp"
65 #include "gc/g1/g1RootProcessor.hpp"
66 #include "gc/g1/g1SATBMarkQueueSet.hpp"
67 #include "gc/g1/g1SegmentedArrayFreeMemoryTask.hpp"
68 #include "gc/g1/g1ServiceThread.hpp"
69 #include "gc/g1/g1ThreadLocalData.hpp"
70 #include "gc/g1/g1Trace.hpp"
71 #include "gc/g1/g1UncommitRegionTask.hpp"
72 #include "gc/g1/g1VMOperations.hpp"
73 #include "gc/g1/g1YoungCollector.hpp"
74 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp"
75 #include "gc/g1/heapRegion.inline.hpp"
76 #include "gc/g1/heapRegionRemSet.inline.hpp"
77 #include "gc/g1/heapRegionSet.inline.hpp"
78 #include "gc/shared/concurrentGCBreakpoints.hpp"
79 #include "gc/shared/gcBehaviours.hpp"
80 #include "gc/shared/gcHeapSummary.hpp"
81 #include "gc/shared/gcId.hpp"
82 #include "gc/shared/gcLocker.hpp"
83 #include "gc/shared/gcTimer.hpp"
84 #include "gc/shared/gcTraceTime.inline.hpp"
85 #include "gc/shared/generationSpec.hpp"
86 #include "gc/shared/isGCActiveMark.hpp"
87 #include "gc/shared/locationPrinter.inline.hpp"
88 #include "gc/shared/oopStorageParState.hpp"
89 #include "gc/shared/preservedMarks.inline.hpp"
90 #include "gc/shared/slidingForwarding.inline.hpp"
91 #include "gc/shared/suspendibleThreadSet.hpp"
92 #include "gc/shared/referenceProcessor.inline.hpp"
93 #include "gc/shared/suspendibleThreadSet.hpp"
94 #include "gc/shared/taskqueue.inline.hpp"
95 #include "gc/shared/taskTerminator.hpp"
96 #include "gc/shared/tlab_globals.hpp"
97 #include "gc/shared/workerPolicy.hpp"
98 #include "gc/shared/weakProcessor.inline.hpp"
99 #include "logging/log.hpp"
100 #include "memory/allocation.hpp"
101 #include "memory/heapInspection.hpp"
102 #include "memory/iterator.hpp"
103 #include "memory/metaspaceUtils.hpp"
104 #include "memory/resourceArea.hpp"
105 #include "memory/universe.hpp"
106 #include "oops/access.inline.hpp"
107 #include "oops/compressedOops.inline.hpp"
108 #include "oops/oop.inline.hpp"
109 #include "runtime/atomic.hpp"
110 #include "runtime/handles.inline.hpp"
111 #include "runtime/init.hpp"
112 #include "runtime/java.hpp"
113 #include "runtime/orderAccess.hpp"
114 #include "runtime/threadSMR.hpp"
115 #include "runtime/vmThread.hpp"
116 #include "utilities/align.hpp"
117 #include "utilities/autoRestore.hpp"
118 #include "utilities/bitMap.inline.hpp"
119 #include "utilities/globalDefinitions.hpp"
120 #include "utilities/stack.inline.hpp"
121
122 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
123
124 // INVARIANTS/NOTES
125 //
126 // All allocation activity covered by the G1CollectedHeap interface is
127 // serialized by acquiring the HeapLock. This happens in mem_allocate
128 // and allocate_new_tlab, which are the "entry" points to the
129 // allocation code from the rest of the JVM. (Note that this does not
130 // apply to TLAB allocation, which is not part of this interface: it
131 // is done by clients of this interface.)
132
133 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
134 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
135 }
136
137 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
138 // The from card cache is not the memory that is actually committed. So we cannot
139 // take advantage of the zero_filled parameter.
140 reset_from_card_cache(start_idx, num_regions);
141 }
142
143 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
144 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
145 cl->set_max_workers(num_workers);
146 workers()->run_task(cl, num_workers);
147 }
148
149 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
150 MemRegion mr) {
151 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
152 }
153
154 // Private methods.
155
156 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
157 HeapRegionType type,
158 bool do_expand,
159 uint node_index) {
160 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
161 "the only time we use this to allocate a humongous region is "
162 "when we are allocating a single humongous region");
163
164 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
165
166 if (res == NULL && do_expand) {
167 // Currently, only attempts to allocate GC alloc regions set
168 // do_expand to true. So, we should only reach here during a
169 // safepoint.
170 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
171
172 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
173 word_size * HeapWordSize);
174
175 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
176 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
177 word_size * HeapWordSize);
178 if (expand_single_region(node_index)) {
179 // Given that expand_single_region() succeeded in expanding the heap, and we
180 // always expand the heap by an amount aligned to the heap
181 // region size, the free list should in theory not be empty.
182 // In either case allocate_free_region() will check for NULL.
183 res = _hrm.allocate_free_region(type, node_index);
184 }
185 }
186 return res;
187 }
188
189 HeapWord*
190 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
191 uint num_regions,
192 size_t word_size) {
193 assert(first_hr != NULL, "pre-condition");
194 assert(is_humongous(word_size), "word_size should be humongous");
195 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
196
197 // Index of last region in the series.
198 uint first = first_hr->hrm_index();
199 uint last = first + num_regions - 1;
200
201 // We need to initialize the region(s) we just discovered. This is
202 // a bit tricky given that it can happen concurrently with
203 // refinement threads refining cards on these regions and
204 // potentially wanting to refine the BOT as they are scanning
205 // those cards (this can happen shortly after a cleanup; see CR
206 // 6991377). So we have to set up the region(s) carefully and in
207 // a specific order.
208
209 // The word size sum of all the regions we will allocate.
210 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
211 assert(word_size <= word_size_sum, "sanity");
212
213 // The passed in hr will be the "starts humongous" region. The header
214 // of the new object will be placed at the bottom of this region.
215 HeapWord* new_obj = first_hr->bottom();
216 // This will be the new top of the new object.
217 HeapWord* obj_top = new_obj + word_size;
218
219 // First, we need to zero the header of the space that we will be
220 // allocating. When we update top further down, some refinement
221 // threads might try to scan the region. By zeroing the header we
222 // ensure that any thread that will try to scan the region will
223 // come across the zero klass word and bail out.
224 //
225 // NOTE: It would not have been correct to have used
226 // CollectedHeap::fill_with_object() and make the space look like
227 // an int array. The thread that is doing the allocation will
228 // later update the object header to a potentially different array
229 // type and, for a very short period of time, the klass and length
230 // fields will be inconsistent. This could cause a refinement
231 // thread to calculate the object size incorrectly.
232 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
233
234 // Next, pad out the unused tail of the last region with filler
235 // objects, for improved usage accounting.
236 // How many words we use for filler objects.
237 size_t word_fill_size = word_size_sum - word_size;
238
239 // How many words memory we "waste" which cannot hold a filler object.
240 size_t words_not_fillable = 0;
241
242 if (word_fill_size >= min_fill_size()) {
243 fill_with_objects(obj_top, word_fill_size);
244 } else if (word_fill_size > 0) {
245 // We have space to fill, but we cannot fit an object there.
246 words_not_fillable = word_fill_size;
247 word_fill_size = 0;
248 }
249
250 // We will set up the first region as "starts humongous". This
251 // will also update the BOT covering all the regions to reflect
252 // that there is a single object that starts at the bottom of the
253 // first region.
254 first_hr->set_starts_humongous(obj_top, word_fill_size);
255 _policy->remset_tracker()->update_at_allocate(first_hr);
256 // Then, if there are any, we will set up the "continues
257 // humongous" regions.
258 HeapRegion* hr = NULL;
259 for (uint i = first + 1; i <= last; ++i) {
260 hr = region_at(i);
261 hr->set_continues_humongous(first_hr);
262 _policy->remset_tracker()->update_at_allocate(hr);
263 }
264
265 // Up to this point no concurrent thread would have been able to
266 // do any scanning on any region in this series. All the top
267 // fields still point to bottom, so the intersection between
268 // [bottom,top] and [card_start,card_end] will be empty. Before we
269 // update the top fields, we'll do a storestore to make sure that
270 // no thread sees the update to top before the zeroing of the
271 // object header and the BOT initialization.
272 OrderAccess::storestore();
273
274 // Now, we will update the top fields of the "continues humongous"
275 // regions except the last one.
276 for (uint i = first; i < last; ++i) {
277 hr = region_at(i);
278 hr->set_top(hr->end());
279 }
280
281 hr = region_at(last);
282 // If we cannot fit a filler object, we must set top to the end
283 // of the humongous object, otherwise we cannot iterate the heap
284 // and the BOT will not be complete.
285 hr->set_top(hr->end() - words_not_fillable);
286
287 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
288 "obj_top should be in last region");
289
290 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
291
292 assert(words_not_fillable == 0 ||
293 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
294 "Miscalculation in humongous allocation");
295
296 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
297
298 for (uint i = first; i <= last; ++i) {
299 hr = region_at(i);
300 _humongous_set.add(hr);
301 _hr_printer.alloc(hr);
302 }
303
304 return new_obj;
305 }
306
307 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
308 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
309 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
310 }
311
312 // If could fit into free regions w/o expansion, try.
313 // Otherwise, if can expand, do so.
314 // Otherwise, if using ex regions might help, try with ex given back.
315 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
316 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
317
318 _verifier->verify_region_sets_optional();
319
320 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
321
322 // Policy: First try to allocate a humongous object in the free list.
323 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
324 if (humongous_start == NULL) {
325 // Policy: We could not find enough regions for the humongous object in the
326 // free list. Look through the heap to find a mix of free and uncommitted regions.
327 // If so, expand the heap and allocate the humongous object.
328 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
329 if (humongous_start != NULL) {
330 // We managed to find a region by expanding the heap.
331 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
332 word_size * HeapWordSize);
333 policy()->record_new_heap_size(num_regions());
334 } else {
335 // Policy: Potentially trigger a defragmentation GC.
336 }
337 }
338
339 HeapWord* result = NULL;
340 if (humongous_start != NULL) {
341 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
342 assert(result != NULL, "it should always return a valid result");
343
344 // A successful humongous object allocation changes the used space
345 // information of the old generation so we need to recalculate the
346 // sizes and update the jstat counters here.
347 monitoring_support()->update_sizes();
348 }
349
350 _verifier->verify_region_sets_optional();
351
352 return result;
353 }
354
355 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
356 size_t requested_size,
357 size_t* actual_size) {
358 assert_heap_not_locked_and_not_at_safepoint();
359 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
360
361 return attempt_allocation(min_size, requested_size, actual_size);
362 }
363
364 HeapWord*
365 G1CollectedHeap::mem_allocate(size_t word_size,
366 bool* gc_overhead_limit_was_exceeded) {
367 assert_heap_not_locked_and_not_at_safepoint();
368
369 if (is_humongous(word_size)) {
370 return attempt_allocation_humongous(word_size);
371 }
372 size_t dummy = 0;
373 return attempt_allocation(word_size, word_size, &dummy);
374 }
375
376 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
377 ResourceMark rm; // For retrieving the thread names in log messages.
378
379 // Make sure you read the note in attempt_allocation_humongous().
380
381 assert_heap_not_locked_and_not_at_safepoint();
382 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
383 "be called for humongous allocation requests");
384
385 // We should only get here after the first-level allocation attempt
386 // (attempt_allocation()) failed to allocate.
387
388 // We will loop until a) we manage to successfully perform the
389 // allocation or b) we successfully schedule a collection which
390 // fails to perform the allocation. b) is the only case when we'll
391 // return NULL.
392 HeapWord* result = NULL;
393 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
394 bool should_try_gc;
395 bool preventive_collection_required = false;
396 uint gc_count_before;
397
398 {
399 MutexLocker x(Heap_lock);
400
401 // Now that we have the lock, we first retry the allocation in case another
402 // thread changed the region while we were waiting to acquire the lock.
403 size_t actual_size;
404 result = _allocator->attempt_allocation(word_size, word_size, &actual_size);
405 if (result != NULL) {
406 return result;
407 }
408
409 preventive_collection_required = policy()->preventive_collection_required(1);
410 if (!preventive_collection_required) {
411 // We've already attempted a lock-free allocation above, so we don't want to
412 // do it again. Let's jump straight to replacing the active region.
413 result = _allocator->attempt_allocation_using_new_region(word_size);
414 if (result != NULL) {
415 return result;
416 }
417
418 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
419 // This is different to when only GCLocker::needs_gc() is set: try to avoid
420 // waiting because the GCLocker is active to not wait too long.
421 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
422 // No need for an ergo message here, can_expand_young_list() does this when
423 // it returns true.
424 result = _allocator->attempt_allocation_force(word_size);
425 if (result != NULL) {
426 return result;
427 }
428 }
429 }
430
431 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
432 // the GCLocker initiated GC has been performed and then retry. This includes
433 // the case when the GC Locker is not active but has not been performed.
434 should_try_gc = !GCLocker::needs_gc();
435 // Read the GC count while still holding the Heap_lock.
436 gc_count_before = total_collections();
437 }
438
439 if (should_try_gc) {
440 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
441 : GCCause::_g1_inc_collection_pause;
442 bool succeeded;
443 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
444 if (result != NULL) {
445 assert(succeeded, "only way to get back a non-NULL result");
446 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
447 Thread::current()->name(), p2i(result));
448 return result;
449 }
450
451 if (succeeded) {
452 // We successfully scheduled a collection which failed to allocate. No
453 // point in trying to allocate further. We'll just return NULL.
454 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
455 SIZE_FORMAT " words", Thread::current()->name(), word_size);
456 return NULL;
457 }
458 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
459 Thread::current()->name(), word_size);
460 } else {
461 // Failed to schedule a collection.
462 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
463 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
464 SIZE_FORMAT " words", Thread::current()->name(), word_size);
465 return NULL;
466 }
467 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
468 // The GCLocker is either active or the GCLocker initiated
469 // GC has not yet been performed. Stall until it is and
470 // then retry the allocation.
471 GCLocker::stall_until_clear();
472 gclocker_retry_count += 1;
473 }
474
475 // We can reach here if we were unsuccessful in scheduling a
476 // collection (because another thread beat us to it) or if we were
477 // stalled due to the GC locker. In either can we should retry the
478 // allocation attempt in case another thread successfully
479 // performed a collection and reclaimed enough space. We do the
480 // first attempt (without holding the Heap_lock) here and the
481 // follow-on attempt will be at the start of the next loop
482 // iteration (after taking the Heap_lock).
483 size_t dummy = 0;
484 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
485 if (result != NULL) {
486 return result;
487 }
488
489 // Give a warning if we seem to be looping forever.
490 if ((QueuedAllocationWarningCount > 0) &&
491 (try_count % QueuedAllocationWarningCount == 0)) {
492 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
493 Thread::current()->name(), try_count, word_size);
494 }
495 }
496
497 ShouldNotReachHere();
498 return NULL;
499 }
500
501 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
502 assert_at_safepoint_on_vm_thread();
503 assert(_archive_allocator == nullptr, "should not be initialized");
504 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
505 }
506
507 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
508 // Allocations in archive regions cannot be of a size that would be considered
509 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
510 // may be different at archive-restore time.
511 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
512 }
513
514 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
515 assert_at_safepoint_on_vm_thread();
516 assert(_archive_allocator != nullptr, "_archive_allocator not initialized");
517 if (is_archive_alloc_too_large(word_size)) {
518 return nullptr;
519 }
520 return _archive_allocator->archive_mem_allocate(word_size);
521 }
522
523 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
524 size_t end_alignment_in_bytes) {
525 assert_at_safepoint_on_vm_thread();
526 assert(_archive_allocator != nullptr, "_archive_allocator not initialized");
527
528 // Call complete_archive to do the real work, filling in the MemRegion
529 // array with the archive regions.
530 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
531 delete _archive_allocator;
532 _archive_allocator = nullptr;
533 }
534
535 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
536 assert(ranges != NULL, "MemRegion array NULL");
537 assert(count != 0, "No MemRegions provided");
538 MemRegion reserved = _hrm.reserved();
539 for (size_t i = 0; i < count; i++) {
540 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
541 return false;
542 }
543 }
544 return true;
545 }
546
547 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
548 size_t count,
549 bool open) {
550 assert(!is_init_completed(), "Expect to be called at JVM init time");
551 assert(ranges != NULL, "MemRegion array NULL");
552 assert(count != 0, "No MemRegions provided");
553 MutexLocker x(Heap_lock);
554
555 MemRegion reserved = _hrm.reserved();
556 HeapWord* prev_last_addr = NULL;
557 HeapRegion* prev_last_region = NULL;
558
559 // Temporarily disable pretouching of heap pages. This interface is used
560 // when mmap'ing archived heap data in, so pre-touching is wasted.
561 FlagSetting fs(AlwaysPreTouch, false);
562
563 // For each specified MemRegion range, allocate the corresponding G1
564 // regions and mark them as archive regions. We expect the ranges
565 // in ascending starting address order, without overlap.
566 for (size_t i = 0; i < count; i++) {
567 MemRegion curr_range = ranges[i];
568 HeapWord* start_address = curr_range.start();
569 size_t word_size = curr_range.word_size();
570 HeapWord* last_address = curr_range.last();
571 size_t commits = 0;
572
573 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
574 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
575 p2i(start_address), p2i(last_address));
576 guarantee(start_address > prev_last_addr,
577 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
578 p2i(start_address), p2i(prev_last_addr));
579 prev_last_addr = last_address;
580
581 // Check for ranges that start in the same G1 region in which the previous
582 // range ended, and adjust the start address so we don't try to allocate
583 // the same region again. If the current range is entirely within that
584 // region, skip it, just adjusting the recorded top.
585 HeapRegion* start_region = _hrm.addr_to_region(start_address);
586 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
587 start_address = start_region->end();
588 if (start_address > last_address) {
589 increase_used(word_size * HeapWordSize);
590 start_region->set_top(last_address + 1);
591 continue;
592 }
593 start_region->set_top(start_address);
594 curr_range = MemRegion(start_address, last_address + 1);
595 start_region = _hrm.addr_to_region(start_address);
596 }
597
598 // Perform the actual region allocation, exiting if it fails.
599 // Then note how much new space we have allocated.
600 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
601 return false;
602 }
603 increase_used(word_size * HeapWordSize);
604 if (commits != 0) {
605 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
606 HeapRegion::GrainWords * HeapWordSize * commits);
607
608 }
609
610 // Mark each G1 region touched by the range as archive, add it to
611 // the old set, and set top.
612 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
613 HeapRegion* last_region = _hrm.addr_to_region(last_address);
614 prev_last_region = last_region;
615
616 while (curr_region != NULL) {
617 assert(curr_region->is_empty() && !curr_region->is_pinned(),
618 "Region already in use (index %u)", curr_region->hrm_index());
619 if (open) {
620 curr_region->set_open_archive();
621 } else {
622 curr_region->set_closed_archive();
623 }
624 _hr_printer.alloc(curr_region);
625 _archive_set.add(curr_region);
626 HeapWord* top;
627 HeapRegion* next_region;
628 if (curr_region != last_region) {
629 top = curr_region->end();
630 next_region = _hrm.next_region_in_heap(curr_region);
631 } else {
632 top = last_address + 1;
633 next_region = NULL;
634 }
635 curr_region->set_top(top);
636 curr_region = next_region;
637 }
638 }
639 return true;
640 }
641
642 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
643 assert(!is_init_completed(), "Expect to be called at JVM init time");
644 assert(ranges != NULL, "MemRegion array NULL");
645 assert(count != 0, "No MemRegions provided");
646 MemRegion reserved = _hrm.reserved();
647 HeapWord *prev_last_addr = NULL;
648 HeapRegion* prev_last_region = NULL;
649
650 // For each MemRegion, create filler objects, if needed, in the G1 regions
651 // that contain the address range. The address range actually within the
652 // MemRegion will not be modified. That is assumed to have been initialized
653 // elsewhere, probably via an mmap of archived heap data.
654 MutexLocker x(Heap_lock);
655 for (size_t i = 0; i < count; i++) {
656 HeapWord* start_address = ranges[i].start();
657 HeapWord* last_address = ranges[i].last();
658
659 assert(reserved.contains(start_address) && reserved.contains(last_address),
660 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
661 p2i(start_address), p2i(last_address));
662 assert(start_address > prev_last_addr,
663 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
664 p2i(start_address), p2i(prev_last_addr));
665
666 HeapRegion* start_region = _hrm.addr_to_region(start_address);
667 HeapRegion* last_region = _hrm.addr_to_region(last_address);
668 HeapWord* bottom_address = start_region->bottom();
669
670 // Check for a range beginning in the same region in which the
671 // previous one ended.
672 if (start_region == prev_last_region) {
673 bottom_address = prev_last_addr + 1;
674 }
675
676 // Verify that the regions were all marked as archive regions by
677 // alloc_archive_regions.
678 HeapRegion* curr_region = start_region;
679 while (curr_region != NULL) {
680 guarantee(curr_region->is_archive(),
681 "Expected archive region at index %u", curr_region->hrm_index());
682 if (curr_region != last_region) {
683 curr_region = _hrm.next_region_in_heap(curr_region);
684 } else {
685 curr_region = NULL;
686 }
687 }
688
689 prev_last_addr = last_address;
690 prev_last_region = last_region;
691
692 // Fill the memory below the allocated range with dummy object(s),
693 // if the region bottom does not match the range start, or if the previous
694 // range ended within the same G1 region, and there is a gap.
695 assert(start_address >= bottom_address, "bottom address should not be greater than start address");
696 if (start_address > bottom_address) {
697 size_t fill_size = pointer_delta(start_address, bottom_address);
698 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
699 increase_used(fill_size * HeapWordSize);
700 }
701 }
702 }
703
704 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
705 size_t desired_word_size,
706 size_t* actual_word_size) {
707 assert_heap_not_locked_and_not_at_safepoint();
708 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
709 "be called for humongous allocation requests");
710
711 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
712
713 if (result == NULL) {
714 *actual_word_size = desired_word_size;
715 result = attempt_allocation_slow(desired_word_size);
716 }
717
718 assert_heap_not_locked();
719 if (result != NULL) {
720 assert(*actual_word_size != 0, "Actual size must have been set here");
721 dirty_young_block(result, *actual_word_size);
722 } else {
723 *actual_word_size = 0;
724 }
725
726 return result;
727 }
728
729 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion* ranges, size_t count) {
730 assert(!is_init_completed(), "Expect to be called at JVM init time");
731 assert(ranges != NULL, "MemRegion array NULL");
732 assert(count != 0, "No MemRegions provided");
733
734 HeapWord* st = ranges[0].start();
735 HeapWord* last = ranges[count-1].last();
736 HeapRegion* hr_st = _hrm.addr_to_region(st);
737 HeapRegion* hr_last = _hrm.addr_to_region(last);
738
739 HeapRegion* hr_curr = hr_st;
740 while (hr_curr != NULL) {
741 hr_curr->update_bot();
742 if (hr_curr != hr_last) {
743 hr_curr = _hrm.next_region_in_heap(hr_curr);
744 } else {
745 hr_curr = NULL;
746 }
747 }
748 }
749
750 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
751 assert(!is_init_completed(), "Expect to be called at JVM init time");
752 assert(ranges != NULL, "MemRegion array NULL");
753 assert(count != 0, "No MemRegions provided");
754 MemRegion reserved = _hrm.reserved();
755 HeapWord* prev_last_addr = NULL;
756 HeapRegion* prev_last_region = NULL;
757 size_t size_used = 0;
758 uint shrink_count = 0;
759
760 // For each Memregion, free the G1 regions that constitute it, and
761 // notify mark-sweep that the range is no longer to be considered 'archive.'
762 MutexLocker x(Heap_lock);
763 for (size_t i = 0; i < count; i++) {
764 HeapWord* start_address = ranges[i].start();
765 HeapWord* last_address = ranges[i].last();
766
767 assert(reserved.contains(start_address) && reserved.contains(last_address),
768 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
769 p2i(start_address), p2i(last_address));
770 assert(start_address > prev_last_addr,
771 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
772 p2i(start_address), p2i(prev_last_addr));
773 size_used += ranges[i].byte_size();
774 prev_last_addr = last_address;
775
776 HeapRegion* start_region = _hrm.addr_to_region(start_address);
777 HeapRegion* last_region = _hrm.addr_to_region(last_address);
778
779 // Check for ranges that start in the same G1 region in which the previous
780 // range ended, and adjust the start address so we don't try to free
781 // the same region again. If the current range is entirely within that
782 // region, skip it.
783 if (start_region == prev_last_region) {
784 start_address = start_region->end();
785 if (start_address > last_address) {
786 continue;
787 }
788 start_region = _hrm.addr_to_region(start_address);
789 }
790 prev_last_region = last_region;
791
792 // After verifying that each region was marked as an archive region by
793 // alloc_archive_regions, set it free and empty and uncommit it.
794 HeapRegion* curr_region = start_region;
795 while (curr_region != NULL) {
796 guarantee(curr_region->is_archive(),
797 "Expected archive region at index %u", curr_region->hrm_index());
798 uint curr_index = curr_region->hrm_index();
799 _archive_set.remove(curr_region);
800 curr_region->set_free();
801 curr_region->set_top(curr_region->bottom());
802 if (curr_region != last_region) {
803 curr_region = _hrm.next_region_in_heap(curr_region);
804 } else {
805 curr_region = NULL;
806 }
807
808 _hrm.shrink_at(curr_index, 1);
809 shrink_count++;
810 }
811 }
812
813 if (shrink_count != 0) {
814 log_debug(gc, ergo, heap)("Attempt heap shrinking (archive regions). Total size: " SIZE_FORMAT "B",
815 HeapRegion::GrainWords * HeapWordSize * shrink_count);
816 // Explicit uncommit.
817 uncommit_regions(shrink_count);
818 }
819 decrease_used(size_used);
820 }
821
822 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
823 ResourceMark rm; // For retrieving the thread names in log messages.
824
825 // The structure of this method has a lot of similarities to
826 // attempt_allocation_slow(). The reason these two were not merged
827 // into a single one is that such a method would require several "if
828 // allocation is not humongous do this, otherwise do that"
829 // conditional paths which would obscure its flow. In fact, an early
830 // version of this code did use a unified method which was harder to
831 // follow and, as a result, it had subtle bugs that were hard to
832 // track down. So keeping these two methods separate allows each to
833 // be more readable. It will be good to keep these two in sync as
834 // much as possible.
835
836 assert_heap_not_locked_and_not_at_safepoint();
837 assert(is_humongous(word_size), "attempt_allocation_humongous() "
838 "should only be called for humongous allocations");
839
840 // Humongous objects can exhaust the heap quickly, so we should check if we
841 // need to start a marking cycle at each humongous object allocation. We do
842 // the check before we do the actual allocation. The reason for doing it
843 // before the allocation is that we avoid having to keep track of the newly
844 // allocated memory while we do a GC.
845 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
846 word_size)) {
847 collect(GCCause::_g1_humongous_allocation);
848 }
849
850 // We will loop until a) we manage to successfully perform the
851 // allocation or b) we successfully schedule a collection which
852 // fails to perform the allocation. b) is the only case when we'll
853 // return NULL.
854 HeapWord* result = NULL;
855 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
856 bool should_try_gc;
857 bool preventive_collection_required = false;
858 uint gc_count_before;
859
860
861 {
862 MutexLocker x(Heap_lock);
863
864 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
865 preventive_collection_required = policy()->preventive_collection_required((uint)size_in_regions);
866 if (!preventive_collection_required) {
867 // Given that humongous objects are not allocated in young
868 // regions, we'll first try to do the allocation without doing a
869 // collection hoping that there's enough space in the heap.
870 result = humongous_obj_allocate(word_size);
871 if (result != NULL) {
872 policy()->old_gen_alloc_tracker()->
873 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
874 return result;
875 }
876 }
877
878 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
879 // the GCLocker initiated GC has been performed and then retry. This includes
880 // the case when the GC Locker is not active but has not been performed.
881 should_try_gc = !GCLocker::needs_gc();
882 // Read the GC count while still holding the Heap_lock.
883 gc_count_before = total_collections();
884 }
885
886 if (should_try_gc) {
887 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
888 : GCCause::_g1_humongous_allocation;
889 bool succeeded;
890 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
891 if (result != NULL) {
892 assert(succeeded, "only way to get back a non-NULL result");
893 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
894 Thread::current()->name(), p2i(result));
895 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
896 policy()->old_gen_alloc_tracker()->
897 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
898 return result;
899 }
900
901 if (succeeded) {
902 // We successfully scheduled a collection which failed to allocate. No
903 // point in trying to allocate further. We'll just return NULL.
904 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
905 SIZE_FORMAT " words", Thread::current()->name(), word_size);
906 return NULL;
907 }
908 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
909 Thread::current()->name(), word_size);
910 } else {
911 // Failed to schedule a collection.
912 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
913 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
914 SIZE_FORMAT " words", Thread::current()->name(), word_size);
915 return NULL;
916 }
917 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
918 // The GCLocker is either active or the GCLocker initiated
919 // GC has not yet been performed. Stall until it is and
920 // then retry the allocation.
921 GCLocker::stall_until_clear();
922 gclocker_retry_count += 1;
923 }
924
925
926 // We can reach here if we were unsuccessful in scheduling a
927 // collection (because another thread beat us to it) or if we were
928 // stalled due to the GC locker. In either can we should retry the
929 // allocation attempt in case another thread successfully
930 // performed a collection and reclaimed enough space.
931 // Humongous object allocation always needs a lock, so we wait for the retry
932 // in the next iteration of the loop, unlike for the regular iteration case.
933 // Give a warning if we seem to be looping forever.
934
935 if ((QueuedAllocationWarningCount > 0) &&
936 (try_count % QueuedAllocationWarningCount == 0)) {
937 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
938 Thread::current()->name(), try_count, word_size);
939 }
940 }
941
942 ShouldNotReachHere();
943 return NULL;
944 }
945
946 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
947 bool expect_null_mutator_alloc_region) {
948 assert_at_safepoint_on_vm_thread();
949 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
950 "the current alloc region was unexpectedly found to be non-NULL");
951
952 if (!is_humongous(word_size)) {
953 return _allocator->attempt_allocation_locked(word_size);
954 } else {
955 HeapWord* result = humongous_obj_allocate(word_size);
956 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
957 collector_state()->set_initiate_conc_mark_if_possible(true);
958 }
959 return result;
960 }
961
962 ShouldNotReachHere();
963 }
964
965 class PostCompactionPrinterClosure: public HeapRegionClosure {
966 private:
967 G1HRPrinter* _hr_printer;
968 public:
969 bool do_heap_region(HeapRegion* hr) {
970 assert(!hr->is_young(), "not expecting to find young regions");
971 _hr_printer->post_compaction(hr);
972 return false;
973 }
974
975 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
976 : _hr_printer(hr_printer) { }
977 };
978
979 void G1CollectedHeap::print_heap_after_full_collection() {
980 // Post collection region logging.
981 // We should do this after we potentially resize the heap so
982 // that all the COMMIT / UNCOMMIT events are generated before
983 // the compaction events.
984 if (_hr_printer.is_active()) {
985 PostCompactionPrinterClosure cl(hr_printer());
986 heap_region_iterate(&cl);
987 }
988 }
989
990 void G1CollectedHeap::abort_concurrent_cycle() {
991 // If we start the compaction before the CM threads finish
992 // scanning the root regions we might trip them over as we'll
993 // be moving objects / updating references. So let's wait until
994 // they are done. By telling them to abort, they should complete
995 // early.
996 _cm->root_regions()->abort();
997 _cm->root_regions()->wait_until_scan_finished();
998
999 // Disable discovery and empty the discovered lists
1000 // for the CM ref processor.
1001 _ref_processor_cm->disable_discovery();
1002 _ref_processor_cm->abandon_partial_discovery();
1003 _ref_processor_cm->verify_no_references_recorded();
1004
1005 // Abandon current iterations of concurrent marking and concurrent
1006 // refinement, if any are in progress.
1007 concurrent_mark()->concurrent_cycle_abort();
1008 }
1009
1010 void G1CollectedHeap::prepare_heap_for_full_collection() {
1011 // Make sure we'll choose a new allocation region afterwards.
1012 _allocator->release_mutator_alloc_regions();
1013 _allocator->abandon_gc_alloc_regions();
1014
1015 // We may have added regions to the current incremental collection
1016 // set between the last GC or pause and now. We need to clear the
1017 // incremental collection set and then start rebuilding it afresh
1018 // after this full GC.
1019 abandon_collection_set(collection_set());
1020
1021 _hrm.remove_all_free_regions();
1022 }
1023
1024 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1025 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1026 assert_used_and_recalculate_used_equal(this);
1027 if (!VerifyBeforeGC) {
1028 return;
1029 }
1030 _verifier->verify_region_sets_optional();
1031 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1032 _verifier->check_bitmaps("Full GC Start");
1033 }
1034
1035 void G1CollectedHeap::prepare_heap_for_mutators() {
1036 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1037 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1038 DEBUG_ONLY(MetaspaceUtils::verify();)
1039
1040 // Prepare heap for normal collections.
1041 assert(num_free_regions() == 0, "we should not have added any free regions");
1042 rebuild_region_sets(false /* free_list_only */);
1043 abort_refinement();
1044 resize_heap_if_necessary();
1045 uncommit_regions_if_necessary();
1046
1047 // Rebuild the code root lists for each region
1048 rebuild_code_roots();
1049
1050 // Purge code root memory
1051 purge_code_root_memory();
1052
1053 // Start a new incremental collection set for the next pause
1054 start_new_collection_set();
1055
1056 _allocator->init_mutator_alloc_regions();
1057
1058 // Post collection state updates.
1059 MetaspaceGC::compute_new_size();
1060 }
1061
1062 void G1CollectedHeap::abort_refinement() {
1063 if (_hot_card_cache->use_cache()) {
1064 _hot_card_cache->reset_hot_cache();
1065 }
1066
1067 // Discard all remembered set updates and reset refinement statistics.
1068 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1069 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1070 "DCQS should be empty");
1071 concurrent_refine()->get_and_reset_refinement_stats();
1072 }
1073
1074 void G1CollectedHeap::verify_after_full_collection() {
1075 if (!VerifyAfterGC) {
1076 return;
1077 }
1078 _hrm.verify_optional();
1079 _verifier->verify_region_sets_optional();
1080 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1081
1082 // This call implicitly verifies that the next bitmap is clear after Full GC.
1083 _verifier->check_bitmaps("Full GC End");
1084
1085 // At this point there should be no regions in the
1086 // entire heap tagged as young.
1087 assert(check_young_list_empty(), "young list should be empty at this point");
1088
1089 // Note: since we've just done a full GC, concurrent
1090 // marking is no longer active. Therefore we need not
1091 // re-enable reference discovery for the CM ref processor.
1092 // That will be done at the start of the next marking cycle.
1093 // We also know that the STW processor should no longer
1094 // discover any new references.
1095 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1096 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1097 _ref_processor_stw->verify_no_references_recorded();
1098 _ref_processor_cm->verify_no_references_recorded();
1099 }
1100
1101 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1102 bool clear_all_soft_refs,
1103 bool do_maximal_compaction) {
1104 assert_at_safepoint_on_vm_thread();
1105
1106 if (GCLocker::check_active_before_gc()) {
1107 // Full GC was not completed.
1108 return false;
1109 }
1110
1111 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1112 soft_ref_policy()->should_clear_all_soft_refs();
1113
1114 G1FullGCMark gc_mark;
1115 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1116 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs, do_maximal_compaction);
1117
1118 collector.prepare_collection();
1119 collector.collect();
1120 collector.complete_collection();
1121
1122 // Full collection was successfully completed.
1123 return true;
1124 }
1125
1126 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1127 // Currently, there is no facility in the do_full_collection(bool) API to notify
1128 // the caller that the collection did not succeed (e.g., because it was locked
1129 // out by the GC locker). So, right now, we'll ignore the return value.
1130 // When clear_all_soft_refs is set we want to do a maximal compaction
1131 // not leaving any dead wood.
1132 bool do_maximal_compaction = clear_all_soft_refs;
1133 bool dummy = do_full_collection(true, /* explicit_gc */
1134 clear_all_soft_refs,
1135 do_maximal_compaction);
1136 }
1137
1138 bool G1CollectedHeap::upgrade_to_full_collection() {
1139 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1140 log_info(gc, ergo)("Attempting full compaction clearing soft references");
1141 bool success = do_full_collection(false /* explicit gc */,
1142 true /* clear_all_soft_refs */,
1143 false /* do_maximal_compaction */);
1144 // do_full_collection only fails if blocked by GC locker and that can't
1145 // be the case here since we only call this when already completed one gc.
1146 assert(success, "invariant");
1147 return success;
1148 }
1149
1150 void G1CollectedHeap::resize_heap_if_necessary() {
1151 assert_at_safepoint_on_vm_thread();
1152
1153 bool should_expand;
1154 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1155
1156 if (resize_amount == 0) {
1157 return;
1158 } else if (should_expand) {
1159 expand(resize_amount, _workers);
1160 } else {
1161 shrink(resize_amount);
1162 }
1163 }
1164
1165 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1166 bool do_gc,
1167 bool maximal_compaction,
1168 bool expect_null_mutator_alloc_region,
1169 bool* gc_succeeded) {
1170 *gc_succeeded = true;
1171 // Let's attempt the allocation first.
1172 HeapWord* result =
1173 attempt_allocation_at_safepoint(word_size,
1174 expect_null_mutator_alloc_region);
1175 if (result != NULL) {
1176 return result;
1177 }
1178
1179 // In a G1 heap, we're supposed to keep allocation from failing by
1180 // incremental pauses. Therefore, at least for now, we'll favor
1181 // expansion over collection. (This might change in the future if we can
1182 // do something smarter than full collection to satisfy a failed alloc.)
1183 result = expand_and_allocate(word_size);
1184 if (result != NULL) {
1185 return result;
1186 }
1187
1188 if (do_gc) {
1189 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1190 // Expansion didn't work, we'll try to do a Full GC.
1191 // If maximal_compaction is set we clear all soft references and don't
1192 // allow any dead wood to be left on the heap.
1193 if (maximal_compaction) {
1194 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
1195 } else {
1196 log_info(gc, ergo)("Attempting full compaction");
1197 }
1198 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1199 maximal_compaction /* clear_all_soft_refs */ ,
1200 maximal_compaction /* do_maximal_compaction */);
1201 }
1202
1203 return NULL;
1204 }
1205
1206 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1207 bool* succeeded) {
1208 assert_at_safepoint_on_vm_thread();
1209
1210 // Attempts to allocate followed by Full GC.
1211 HeapWord* result =
1212 satisfy_failed_allocation_helper(word_size,
1213 true, /* do_gc */
1214 false, /* maximum_collection */
1215 false, /* expect_null_mutator_alloc_region */
1216 succeeded);
1217
1218 if (result != NULL || !*succeeded) {
1219 return result;
1220 }
1221
1222 // Attempts to allocate followed by Full GC that will collect all soft references.
1223 result = satisfy_failed_allocation_helper(word_size,
1224 true, /* do_gc */
1225 true, /* maximum_collection */
1226 true, /* expect_null_mutator_alloc_region */
1227 succeeded);
1228
1229 if (result != NULL || !*succeeded) {
1230 return result;
1231 }
1232
1233 // Attempts to allocate, no GC
1234 result = satisfy_failed_allocation_helper(word_size,
1235 false, /* do_gc */
1236 false, /* maximum_collection */
1237 true, /* expect_null_mutator_alloc_region */
1238 succeeded);
1239
1240 if (result != NULL) {
1241 return result;
1242 }
1243
1244 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1245 "Flag should have been handled and cleared prior to this point");
1246
1247 // What else? We might try synchronous finalization later. If the total
1248 // space available is large enough for the allocation, then a more
1249 // complete compaction phase than we've tried so far might be
1250 // appropriate.
1251 return NULL;
1252 }
1253
1254 // Attempting to expand the heap sufficiently
1255 // to support an allocation of the given "word_size". If
1256 // successful, perform the allocation and return the address of the
1257 // allocated block, or else "NULL".
1258
1259 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1260 assert_at_safepoint_on_vm_thread();
1261
1262 _verifier->verify_region_sets_optional();
1263
1264 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1265 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1266 word_size * HeapWordSize);
1267
1268
1269 if (expand(expand_bytes, _workers)) {
1270 _hrm.verify_optional();
1271 _verifier->verify_region_sets_optional();
1272 return attempt_allocation_at_safepoint(word_size,
1273 false /* expect_null_mutator_alloc_region */);
1274 }
1275 return NULL;
1276 }
1277
1278 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1279 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1280 aligned_expand_bytes = align_up(aligned_expand_bytes,
1281 HeapRegion::GrainBytes);
1282
1283 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1284 expand_bytes, aligned_expand_bytes);
1285
1286 if (is_maximal_no_gc()) {
1287 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1288 return false;
1289 }
1290
1291 double expand_heap_start_time_sec = os::elapsedTime();
1292 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1293 assert(regions_to_expand > 0, "Must expand by at least one region");
1294
1295 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1296 if (expand_time_ms != NULL) {
1297 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1298 }
1299
1300 if (expanded_by > 0) {
1301 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1302 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1303 policy()->record_new_heap_size(num_regions());
1304 } else {
1305 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1306
1307 // The expansion of the virtual storage space was unsuccessful.
1308 // Let's see if it was because we ran out of swap.
1309 if (G1ExitOnExpansionFailure &&
1310 _hrm.available() >= regions_to_expand) {
1311 // We had head room...
1312 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1313 }
1314 }
1315 return expanded_by > 0;
1316 }
1317
1318 bool G1CollectedHeap::expand_single_region(uint node_index) {
1319 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1320
1321 if (expanded_by == 0) {
1322 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1323 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1324 return false;
1325 }
1326
1327 policy()->record_new_heap_size(num_regions());
1328 return true;
1329 }
1330
1331 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1332 size_t aligned_shrink_bytes =
1333 ReservedSpace::page_align_size_down(shrink_bytes);
1334 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1335 HeapRegion::GrainBytes);
1336 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1337
1338 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1339 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1340
1341 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",
1342 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1343 if (num_regions_removed > 0) {
1344 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1345 policy()->record_new_heap_size(num_regions());
1346 } else {
1347 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1348 }
1349 }
1350
1351 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1352 _verifier->verify_region_sets_optional();
1353
1354 // We should only reach here at the end of a Full GC or during Remark which
1355 // means we should not not be holding to any GC alloc regions. The method
1356 // below will make sure of that and do any remaining clean up.
1357 _allocator->abandon_gc_alloc_regions();
1358
1359 // Instead of tearing down / rebuilding the free lists here, we
1360 // could instead use the remove_all_pending() method on free_list to
1361 // remove only the ones that we need to remove.
1362 _hrm.remove_all_free_regions();
1363 shrink_helper(shrink_bytes);
1364 rebuild_region_sets(true /* free_list_only */);
1365
1366 _hrm.verify_optional();
1367 _verifier->verify_region_sets_optional();
1368 }
1369
1370 class OldRegionSetChecker : public HeapRegionSetChecker {
1371 public:
1372 void check_mt_safety() {
1373 // Master Old Set MT safety protocol:
1374 // (a) If we're at a safepoint, operations on the master old set
1375 // should be invoked:
1376 // - by the VM thread (which will serialize them), or
1377 // - by the GC workers while holding the FreeList_lock, if we're
1378 // at a safepoint for an evacuation pause (this lock is taken
1379 // anyway when an GC alloc region is retired so that a new one
1380 // is allocated from the free list), or
1381 // - by the GC workers while holding the OldSets_lock, if we're at a
1382 // safepoint for a cleanup pause.
1383 // (b) If we're not at a safepoint, operations on the master old set
1384 // should be invoked while holding the Heap_lock.
1385
1386 if (SafepointSynchronize::is_at_safepoint()) {
1387 guarantee(Thread::current()->is_VM_thread() ||
1388 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1389 "master old set MT safety protocol at a safepoint");
1390 } else {
1391 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1392 }
1393 }
1394 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1395 const char* get_description() { return "Old Regions"; }
1396 };
1397
1398 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1399 public:
1400 void check_mt_safety() {
1401 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1402 "May only change archive regions during initialization or safepoint.");
1403 }
1404 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1405 const char* get_description() { return "Archive Regions"; }
1406 };
1407
1408 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1409 public:
1410 void check_mt_safety() {
1411 // Humongous Set MT safety protocol:
1412 // (a) If we're at a safepoint, operations on the master humongous
1413 // set should be invoked by either the VM thread (which will
1414 // serialize them) or by the GC workers while holding the
1415 // OldSets_lock.
1416 // (b) If we're not at a safepoint, operations on the master
1417 // humongous set should be invoked while holding the Heap_lock.
1418
1419 if (SafepointSynchronize::is_at_safepoint()) {
1420 guarantee(Thread::current()->is_VM_thread() ||
1421 OldSets_lock->owned_by_self(),
1422 "master humongous set MT safety protocol at a safepoint");
1423 } else {
1424 guarantee(Heap_lock->owned_by_self(),
1425 "master humongous set MT safety protocol outside a safepoint");
1426 }
1427 }
1428 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1429 const char* get_description() { return "Humongous Regions"; }
1430 };
1431
1432 G1CollectedHeap::G1CollectedHeap() :
1433 CollectedHeap(),
1434 _service_thread(NULL),
1435 _periodic_gc_task(NULL),
1436 _free_segmented_array_memory_task(NULL),
1437 _workers(NULL),
1438 _card_table(NULL),
1439 _collection_pause_end(Ticks::now()),
1440 _soft_ref_policy(),
1441 _old_set("Old Region Set", new OldRegionSetChecker()),
1442 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1443 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1444 _bot(NULL),
1445 _listener(),
1446 _numa(G1NUMA::create()),
1447 _hrm(),
1448 _allocator(NULL),
1449 _evac_failure_injector(),
1450 _verifier(NULL),
1451 _summary_bytes_used(0),
1452 _bytes_used_during_gc(0),
1453 _archive_allocator(nullptr),
1454 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1455 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1456 _monitoring_support(nullptr),
1457 _humongous_reclaim_candidates(),
1458 _num_humongous_objects(0),
1459 _num_humongous_reclaim_candidates(0),
1460 _hr_printer(),
1461 _collector_state(),
1462 _old_marking_cycles_started(0),
1463 _old_marking_cycles_completed(0),
1464 _eden(),
1465 _survivor(),
1466 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1467 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1468 _policy(new G1Policy(_gc_timer_stw)),
1469 _heap_sizing_policy(NULL),
1470 _collection_set(this, _policy),
1471 _hot_card_cache(NULL),
1472 _rem_set(NULL),
1473 _card_set_config(),
1474 _cm(NULL),
1475 _cm_thread(NULL),
1476 _cr(NULL),
1477 _task_queues(NULL),
1478 _ref_processor_stw(NULL),
1479 _is_alive_closure_stw(this),
1480 _is_subject_to_discovery_stw(this),
1481 _ref_processor_cm(NULL),
1482 _is_alive_closure_cm(this),
1483 _is_subject_to_discovery_cm(this),
1484 _region_attr() {
1485
1486 _verifier = new G1HeapVerifier(this);
1487
1488 _allocator = new G1Allocator(this);
1489
1490 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1491
1492 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1493
1494 // Override the default _filler_array_max_size so that no humongous filler
1495 // objects are created.
1496 _filler_array_max_size = _humongous_object_threshold_in_words;
1497
1498 uint n_queues = ParallelGCThreads;
1499 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1500
1501 for (uint i = 0; i < n_queues; i++) {
1502 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1503 _task_queues->register_queue(i, q);
1504 }
1505
1506 _gc_tracer_stw->initialize();
1507
1508 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1509 }
1510
1511 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1512 size_t size,
1513 size_t translation_factor) {
1514 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1515 // Allocate a new reserved space, preferring to use large pages.
1516 ReservedSpace rs(size, preferred_page_size);
1517 size_t page_size = rs.page_size();
1518 G1RegionToSpaceMapper* result =
1519 G1RegionToSpaceMapper::create_mapper(rs,
1520 size,
1521 page_size,
1522 HeapRegion::GrainBytes,
1523 translation_factor,
1524 mtGC);
1525
1526 os::trace_page_sizes_for_requested_size(description,
1527 size,
1528 page_size,
1529 preferred_page_size,
1530 rs.base(),
1531 rs.size());
1532
1533 return result;
1534 }
1535
1536 jint G1CollectedHeap::initialize_concurrent_refinement() {
1537 jint ecode = JNI_OK;
1538 _cr = G1ConcurrentRefine::create(&ecode);
1539 return ecode;
1540 }
1541
1542 jint G1CollectedHeap::initialize_service_thread() {
1543 _service_thread = new G1ServiceThread();
1544 if (_service_thread->osthread() == NULL) {
1545 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1546 return JNI_ENOMEM;
1547 }
1548 return JNI_OK;
1549 }
1550
1551 jint G1CollectedHeap::initialize() {
1552
1553 // Necessary to satisfy locking discipline assertions.
1554
1555 MutexLocker x(Heap_lock);
1556
1557 // While there are no constraints in the GC code that HeapWordSize
1558 // be any particular value, there are multiple other areas in the
1559 // system which believe this to be true (e.g. oop->object_size in some
1560 // cases incorrectly returns the size in wordSize units rather than
1561 // HeapWordSize).
1562 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1563
1564 size_t init_byte_size = InitialHeapSize;
1565 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1566
1567 // Ensure that the sizes are properly aligned.
1568 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1569 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1570 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1571
1572 // Reserve the maximum.
1573
1574 // When compressed oops are enabled, the preferred heap base
1575 // is calculated by subtracting the requested size from the
1576 // 32Gb boundary and using the result as the base address for
1577 // heap reservation. If the requested size is not aligned to
1578 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1579 // into the ReservedHeapSpace constructor) then the actual
1580 // base of the reserved heap may end up differing from the
1581 // address that was requested (i.e. the preferred heap base).
1582 // If this happens then we could end up using a non-optimal
1583 // compressed oops mode.
1584
1585 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1586 HeapAlignment);
1587
1588 initialize_reserved_region(heap_rs);
1589
1590 _forwarding = new SlidingForwarding(heap_rs.region(), HeapRegion::LogOfHRGrainBytes - LogHeapWordSize);
1591
1592 // Create the barrier set for the entire reserved region.
1593 G1CardTable* ct = new G1CardTable(heap_rs.region());
1594 ct->initialize();
1595 G1BarrierSet* bs = new G1BarrierSet(ct);
1596 bs->initialize();
1597 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1598 BarrierSet::set_barrier_set(bs);
1599 _card_table = ct;
1600
1601 {
1602 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1603 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1604 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1605 }
1606
1607 // Create the hot card cache.
1608 _hot_card_cache = new G1HotCardCache(this);
1609
1610 // Create space mappers.
1611 size_t page_size = heap_rs.page_size();
1612 G1RegionToSpaceMapper* heap_storage =
1613 G1RegionToSpaceMapper::create_mapper(heap_rs,
1614 heap_rs.size(),
1615 page_size,
1616 HeapRegion::GrainBytes,
1617 1,
1618 mtJavaHeap);
1619 if(heap_storage == NULL) {
1620 vm_shutdown_during_initialization("Could not initialize G1 heap");
1621 return JNI_ERR;
1622 }
1623
1624 os::trace_page_sizes("Heap",
1625 MinHeapSize,
1626 reserved_byte_size,
1627 page_size,
1628 heap_rs.base(),
1629 heap_rs.size());
1630 heap_storage->set_mapping_changed_listener(&_listener);
1631
1632 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1633 G1RegionToSpaceMapper* bot_storage =
1634 create_aux_memory_mapper("Block Offset Table",
1635 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1636 G1BlockOffsetTable::heap_map_factor());
1637
1638 G1RegionToSpaceMapper* cardtable_storage =
1639 create_aux_memory_mapper("Card Table",
1640 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1641 G1CardTable::heap_map_factor());
1642
1643 G1RegionToSpaceMapper* card_counts_storage =
1644 create_aux_memory_mapper("Card Counts Table",
1645 G1CardCounts::compute_size(heap_rs.size() / HeapWordSize),
1646 G1CardCounts::heap_map_factor());
1647
1648 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1649 G1RegionToSpaceMapper* prev_bitmap_storage =
1650 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1651 G1RegionToSpaceMapper* next_bitmap_storage =
1652 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1653
1654 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1655 _card_table->initialize(cardtable_storage);
1656
1657 // Do later initialization work for concurrent refinement.
1658 _hot_card_cache->initialize(card_counts_storage);
1659
1660 // 6843694 - ensure that the maximum region index can fit
1661 // in the remembered set structures.
1662 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1663 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1664
1665 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1666 // start within the first card.
1667 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1668 G1FromCardCache::initialize(max_reserved_regions());
1669 // Also create a G1 rem set.
1670 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1671 _rem_set->initialize(max_reserved_regions());
1672
1673 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1674 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1675 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1676 "too many cards per region");
1677
1678 HeapRegionRemSet::initialize(_reserved);
1679
1680 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1681
1682 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1683
1684 {
1685 size_t granularity = HeapRegion::GrainBytes;
1686
1687 _region_attr.initialize(reserved(), granularity);
1688 _humongous_reclaim_candidates.initialize(reserved(), granularity);
1689 }
1690
1691 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1692 if (_workers == NULL) {
1693 return JNI_ENOMEM;
1694 }
1695 _workers->initialize_workers();
1696
1697 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1698
1699 // Create the G1ConcurrentMark data structure and thread.
1700 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1701 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1702 _cm_thread = _cm->cm_thread();
1703
1704 // Now expand into the initial heap size.
1705 if (!expand(init_byte_size, _workers)) {
1706 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1707 return JNI_ENOMEM;
1708 }
1709
1710 // Perform any initialization actions delegated to the policy.
1711 policy()->init(this, &_collection_set);
1712
1713 jint ecode = initialize_concurrent_refinement();
1714 if (ecode != JNI_OK) {
1715 return ecode;
1716 }
1717
1718 ecode = initialize_service_thread();
1719 if (ecode != JNI_OK) {
1720 return ecode;
1721 }
1722
1723 // Initialize and schedule sampling task on service thread.
1724 _rem_set->initialize_sampling_task(service_thread());
1725
1726 // Create and schedule the periodic gc task on the service thread.
1727 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1728 _service_thread->register_task(_periodic_gc_task);
1729
1730 _free_segmented_array_memory_task = new G1SegmentedArrayFreeMemoryTask("Card Set Free Memory Task");
1731 _service_thread->register_task(_free_segmented_array_memory_task);
1732
1733 // Here we allocate the dummy HeapRegion that is required by the
1734 // G1AllocRegion class.
1735 HeapRegion* dummy_region = _hrm.get_dummy_region();
1736
1737 // We'll re-use the same region whether the alloc region will
1738 // require BOT updates or not and, if it doesn't, then a non-young
1739 // region will complain that it cannot support allocations without
1740 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1741 dummy_region->set_eden();
1742 // Make sure it's full.
1743 dummy_region->set_top(dummy_region->end());
1744 G1AllocRegion::setup(this, dummy_region);
1745
1746 _allocator->init_mutator_alloc_regions();
1747
1748 // Do create of the monitoring and management support so that
1749 // values in the heap have been properly initialized.
1750 _monitoring_support = new G1MonitoringSupport(this);
1751
1752 _collection_set.initialize(max_reserved_regions());
1753
1754 evac_failure_injector()->reset();
1755
1756 G1InitLogger::print();
1757
1758 return JNI_OK;
1759 }
1760
1761 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1762 return _cm_thread->should_terminate();
1763 }
1764
1765 void G1CollectedHeap::stop() {
1766 // Stop all concurrent threads. We do this to make sure these threads
1767 // do not continue to execute and access resources (e.g. logging)
1768 // that are destroyed during shutdown.
1769 _cr->stop();
1770 _service_thread->stop();
1771 _cm_thread->stop();
1772 }
1773
1774 void G1CollectedHeap::safepoint_synchronize_begin() {
1775 SuspendibleThreadSet::synchronize();
1776 }
1777
1778 void G1CollectedHeap::safepoint_synchronize_end() {
1779 SuspendibleThreadSet::desynchronize();
1780 }
1781
1782 void G1CollectedHeap::post_initialize() {
1783 CollectedHeap::post_initialize();
1784 ref_processing_init();
1785 }
1786
1787 void G1CollectedHeap::ref_processing_init() {
1788 // Reference processing in G1 currently works as follows:
1789 //
1790 // * There are two reference processor instances. One is
1791 // used to record and process discovered references
1792 // during concurrent marking; the other is used to
1793 // record and process references during STW pauses
1794 // (both full and incremental).
1795 // * Both ref processors need to 'span' the entire heap as
1796 // the regions in the collection set may be dotted around.
1797 //
1798 // * For the concurrent marking ref processor:
1799 // * Reference discovery is enabled at concurrent start.
1800 // * Reference discovery is disabled and the discovered
1801 // references processed etc during remarking.
1802 // * Reference discovery is MT (see below).
1803 // * Reference discovery requires a barrier (see below).
1804 // * Reference processing may or may not be MT
1805 // (depending on the value of ParallelRefProcEnabled
1806 // and ParallelGCThreads).
1807 // * A full GC disables reference discovery by the CM
1808 // ref processor and abandons any entries on it's
1809 // discovered lists.
1810 //
1811 // * For the STW processor:
1812 // * Non MT discovery is enabled at the start of a full GC.
1813 // * Processing and enqueueing during a full GC is non-MT.
1814 // * During a full GC, references are processed after marking.
1815 //
1816 // * Discovery (may or may not be MT) is enabled at the start
1817 // of an incremental evacuation pause.
1818 // * References are processed near the end of a STW evacuation pause.
1819 // * For both types of GC:
1820 // * Discovery is atomic - i.e. not concurrent.
1821 // * Reference discovery will not need a barrier.
1822
1823 // Concurrent Mark ref processor
1824 _ref_processor_cm =
1825 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1826 ParallelGCThreads, // degree of mt processing
1827 // We discover with the gc worker threads during Remark, so both
1828 // thread counts must be considered for discovery.
1829 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1830 true, // Reference discovery is concurrent
1831 &_is_alive_closure_cm); // is alive closure
1832
1833 // STW ref processor
1834 _ref_processor_stw =
1835 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1836 ParallelGCThreads, // degree of mt processing
1837 ParallelGCThreads, // degree of mt discovery
1838 false, // Reference discovery is not concurrent
1839 &_is_alive_closure_stw); // is alive closure
1840 }
1841
1842 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1843 return &_soft_ref_policy;
1844 }
1845
1846 size_t G1CollectedHeap::capacity() const {
1847 return _hrm.length() * HeapRegion::GrainBytes;
1848 }
1849
1850 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1851 return _hrm.total_free_bytes();
1852 }
1853
1854 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1855 _hot_card_cache->drain(cl, worker_id);
1856 }
1857
1858 // Computes the sum of the storage used by the various regions.
1859 size_t G1CollectedHeap::used() const {
1860 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1861 assert(_archive_allocator == nullptr, "must be, should not contribute to used");
1862 return result;
1863 }
1864
1865 size_t G1CollectedHeap::used_unlocked() const {
1866 return _summary_bytes_used;
1867 }
1868
1869 class SumUsedClosure: public HeapRegionClosure {
1870 size_t _used;
1871 public:
1872 SumUsedClosure() : _used(0) {}
1873 bool do_heap_region(HeapRegion* r) {
1874 _used += r->used();
1875 return false;
1876 }
1877 size_t result() { return _used; }
1878 };
1879
1880 size_t G1CollectedHeap::recalculate_used() const {
1881 SumUsedClosure blk;
1882 heap_region_iterate(&blk);
1883 return blk.result();
1884 }
1885
1886 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1887 switch (cause) {
1888 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1889 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1890 case GCCause::_wb_conc_mark: return true;
1891 default : return false;
1892 }
1893 }
1894
1895 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1896 switch (cause) {
1897 case GCCause::_g1_humongous_allocation: return true;
1898 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1899 case GCCause::_wb_breakpoint: return true;
1900 default: return is_user_requested_concurrent_full_gc(cause);
1901 }
1902 }
1903
1904 #ifndef PRODUCT
1905 void G1CollectedHeap::allocate_dummy_regions() {
1906 // Let's fill up most of the region
1907 size_t word_size = HeapRegion::GrainWords - 1024;
1908 // And as a result the region we'll allocate will be humongous.
1909 guarantee(is_humongous(word_size), "sanity");
1910
1911 // _filler_array_max_size is set to humongous object threshold
1912 // but temporarily change it to use CollectedHeap::fill_with_object().
1913 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1914
1915 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1916 // Let's use the existing mechanism for the allocation
1917 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1918 if (dummy_obj != NULL) {
1919 MemRegion mr(dummy_obj, word_size);
1920 CollectedHeap::fill_with_object(mr);
1921 } else {
1922 // If we can't allocate once, we probably cannot allocate
1923 // again. Let's get out of the loop.
1924 break;
1925 }
1926 }
1927 }
1928 #endif // !PRODUCT
1929
1930 void G1CollectedHeap::increment_old_marking_cycles_started() {
1931 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1932 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1933 "Wrong marking cycle count (started: %d, completed: %d)",
1934 _old_marking_cycles_started, _old_marking_cycles_completed);
1935
1936 _old_marking_cycles_started++;
1937 }
1938
1939 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1940 bool whole_heap_examined) {
1941 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1942
1943 // We assume that if concurrent == true, then the caller is a
1944 // concurrent thread that was joined the Suspendible Thread
1945 // Set. If there's ever a cheap way to check this, we should add an
1946 // assert here.
1947
1948 // Given that this method is called at the end of a Full GC or of a
1949 // concurrent cycle, and those can be nested (i.e., a Full GC can
1950 // interrupt a concurrent cycle), the number of full collections
1951 // completed should be either one (in the case where there was no
1952 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1953 // behind the number of full collections started.
1954
1955 // This is the case for the inner caller, i.e. a Full GC.
1956 assert(concurrent ||
1957 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1958 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1959 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1960 "is inconsistent with _old_marking_cycles_completed = %u",
1961 _old_marking_cycles_started, _old_marking_cycles_completed);
1962
1963 // This is the case for the outer caller, i.e. the concurrent cycle.
1964 assert(!concurrent ||
1965 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1966 "for outer caller (concurrent cycle): "
1967 "_old_marking_cycles_started = %u "
1968 "is inconsistent with _old_marking_cycles_completed = %u",
1969 _old_marking_cycles_started, _old_marking_cycles_completed);
1970
1971 _old_marking_cycles_completed += 1;
1972 if (whole_heap_examined) {
1973 // Signal that we have completed a visit to all live objects.
1974 record_whole_heap_examined_timestamp();
1975 }
1976
1977 // We need to clear the "in_progress" flag in the CM thread before
1978 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1979 // is set) so that if a waiter requests another System.gc() it doesn't
1980 // incorrectly see that a marking cycle is still in progress.
1981 if (concurrent) {
1982 _cm_thread->set_idle();
1983 }
1984
1985 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1986 // for a full GC to finish that their wait is over.
1987 ml.notify_all();
1988 }
1989
1990 // Helper for collect().
1991 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1992 MutexLocker ml(Heap_lock);
1993 return G1GCCounters(g1h);
1994 }
1995
1996 void G1CollectedHeap::collect(GCCause::Cause cause) {
1997 try_collect(cause, collection_counters(this));
1998 }
1999
2000 // Return true if (x < y) with allowance for wraparound.
2001 static bool gc_counter_less_than(uint x, uint y) {
2002 return (x - y) > (UINT_MAX/2);
2003 }
2004
2005 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2006 // Macro so msg printing is format-checked.
2007 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2008 do { \
2009 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2010 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2011 ResourceMark rm; /* For thread name. */ \
2012 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2013 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2014 Thread::current()->name(), \
2015 GCCause::to_string(cause)); \
2016 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2017 } \
2018 } while (0)
2019
2020 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2021 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2022
2023 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2024 uint gc_counter,
2025 uint old_marking_started_before) {
2026 assert_heap_not_locked();
2027 assert(should_do_concurrent_full_gc(cause),
2028 "Non-concurrent cause %s", GCCause::to_string(cause));
2029
2030 for (uint i = 1; true; ++i) {
2031 // Try to schedule concurrent start evacuation pause that will
2032 // start a concurrent cycle.
2033 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2034 VM_G1TryInitiateConcMark op(gc_counter,
2035 cause,
2036 policy()->max_pause_time_ms());
2037 VMThread::execute(&op);
2038
2039 // Request is trivially finished.
2040 if (cause == GCCause::_g1_periodic_collection) {
2041 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2042 return op.gc_succeeded();
2043 }
2044
2045 // If VMOp skipped initiating concurrent marking cycle because
2046 // we're terminating, then we're done.
2047 if (op.terminating()) {
2048 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2049 return false;
2050 }
2051
2052 // Lock to get consistent set of values.
2053 uint old_marking_started_after;
2054 uint old_marking_completed_after;
2055 {
2056 MutexLocker ml(Heap_lock);
2057 // Update gc_counter for retrying VMOp if needed. Captured here to be
2058 // consistent with the values we use below for termination tests. If
2059 // a retry is needed after a possible wait, and another collection
2060 // occurs in the meantime, it will cause our retry to be skipped and
2061 // we'll recheck for termination with updated conditions from that
2062 // more recent collection. That's what we want, rather than having
2063 // our retry possibly perform an unnecessary collection.
2064 gc_counter = total_collections();
2065 old_marking_started_after = _old_marking_cycles_started;
2066 old_marking_completed_after = _old_marking_cycles_completed;
2067 }
2068
2069 if (cause == GCCause::_wb_breakpoint) {
2070 if (op.gc_succeeded()) {
2071 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2072 return true;
2073 }
2074 // When _wb_breakpoint there can't be another cycle or deferred.
2075 assert(!op.cycle_already_in_progress(), "invariant");
2076 assert(!op.whitebox_attached(), "invariant");
2077 // Concurrent cycle attempt might have been cancelled by some other
2078 // collection, so retry. Unlike other cases below, we want to retry
2079 // even if cancelled by a STW full collection, because we really want
2080 // to start a concurrent cycle.
2081 if (old_marking_started_before != old_marking_started_after) {
2082 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2083 old_marking_started_before = old_marking_started_after;
2084 }
2085 } else if (!GCCause::is_user_requested_gc(cause)) {
2086 // For an "automatic" (not user-requested) collection, we just need to
2087 // ensure that progress is made.
2088 //
2089 // Request is finished if any of
2090 // (1) the VMOp successfully performed a GC,
2091 // (2) a concurrent cycle was already in progress,
2092 // (3) whitebox is controlling concurrent cycles,
2093 // (4) a new cycle was started (by this thread or some other), or
2094 // (5) a Full GC was performed.
2095 // Cases (4) and (5) are detected together by a change to
2096 // _old_marking_cycles_started.
2097 //
2098 // Note that (1) does not imply (4). If we're still in the mixed
2099 // phase of an earlier concurrent collection, the request to make the
2100 // collection a concurrent start won't be honored. If we don't check for
2101 // both conditions we'll spin doing back-to-back collections.
2102 if (op.gc_succeeded() ||
2103 op.cycle_already_in_progress() ||
2104 op.whitebox_attached() ||
2105 (old_marking_started_before != old_marking_started_after)) {
2106 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2107 return true;
2108 }
2109 } else { // User-requested GC.
2110 // For a user-requested collection, we want to ensure that a complete
2111 // full collection has been performed before returning, but without
2112 // waiting for more than needed.
2113
2114 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2115 // new cycle was started. That's good, because it's not clear what we
2116 // should do otherwise. Trying again just does back to back GCs.
2117 // Can't wait for someone else to start a cycle. And returning fails
2118 // to meet the goal of ensuring a full collection was performed.
2119 assert(!op.gc_succeeded() ||
2120 (old_marking_started_before != old_marking_started_after),
2121 "invariant: succeeded %s, started before %u, started after %u",
2122 BOOL_TO_STR(op.gc_succeeded()),
2123 old_marking_started_before, old_marking_started_after);
2124
2125 // Request is finished if a full collection (concurrent or stw)
2126 // was started after this request and has completed, e.g.
2127 // started_before < completed_after.
2128 if (gc_counter_less_than(old_marking_started_before,
2129 old_marking_completed_after)) {
2130 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2131 return true;
2132 }
2133
2134 if (old_marking_started_after != old_marking_completed_after) {
2135 // If there is an in-progress cycle (possibly started by us), then
2136 // wait for that cycle to complete, e.g.
2137 // while completed_now < started_after.
2138 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2139 MonitorLocker ml(G1OldGCCount_lock);
2140 while (gc_counter_less_than(_old_marking_cycles_completed,
2141 old_marking_started_after)) {
2142 ml.wait();
2143 }
2144 // Request is finished if the collection we just waited for was
2145 // started after this request.
2146 if (old_marking_started_before != old_marking_started_after) {
2147 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2148 return true;
2149 }
2150 }
2151
2152 // If VMOp was successful then it started a new cycle that the above
2153 // wait &etc should have recognized as finishing this request. This
2154 // differs from a non-user-request, where gc_succeeded does not imply
2155 // a new cycle was started.
2156 assert(!op.gc_succeeded(), "invariant");
2157
2158 if (op.cycle_already_in_progress()) {
2159 // If VMOp failed because a cycle was already in progress, it
2160 // is now complete. But it didn't finish this user-requested
2161 // GC, so try again.
2162 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2163 continue;
2164 } else if (op.whitebox_attached()) {
2165 // If WhiteBox wants control, wait for notification of a state
2166 // change in the controller, then try again. Don't wait for
2167 // release of control, since collections may complete while in
2168 // control. Note: This won't recognize a STW full collection
2169 // while waiting; we can't wait on multiple monitors.
2170 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2171 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2172 if (ConcurrentGCBreakpoints::is_controlled()) {
2173 ml.wait();
2174 }
2175 continue;
2176 }
2177 }
2178
2179 // Collection failed and should be retried.
2180 assert(op.transient_failure(), "invariant");
2181
2182 if (GCLocker::is_active_and_needs_gc()) {
2183 // If GCLocker is active, wait until clear before retrying.
2184 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2185 GCLocker::stall_until_clear();
2186 }
2187
2188 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2189 }
2190 }
2191
2192 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
2193 const G1GCCounters& counters_before) {
2194 if (should_do_concurrent_full_gc(cause)) {
2195 return try_collect_concurrently(cause,
2196 counters_before.total_collections(),
2197 counters_before.old_marking_cycles_started());
2198 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
2199 // Indicate failure to be consistent with VMOp failure due to
2200 // another collection slipping in after our gc_count but before
2201 // our request is processed.
2202 return false;
2203 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2204 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2205
2206 // Schedule a standard evacuation pause. We're setting word_size
2207 // to 0 which means that we are not requesting a post-GC allocation.
2208 VM_G1CollectForAllocation op(0, /* word_size */
2209 counters_before.total_collections(),
2210 cause,
2211 policy()->max_pause_time_ms());
2212 VMThread::execute(&op);
2213 return op.gc_succeeded();
2214 } else {
2215 // Schedule a Full GC.
2216 VM_G1CollectFull op(counters_before.total_collections(),
2217 counters_before.total_full_collections(),
2218 cause);
2219 VMThread::execute(&op);
2220 return op.gc_succeeded();
2221 }
2222 }
2223
2224 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
2225 GCCauseSetter x(this, gc_cause);
2226
2227 // At this point we are supposed to start a concurrent cycle. We
2228 // will do so if one is not already in progress.
2229 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
2230 if (should_start) {
2231 double pause_target = policy()->max_pause_time_ms();
2232 do_collection_pause_at_safepoint(pause_target);
2233 }
2234 }
2235
2236 bool G1CollectedHeap::is_in(const void* p) const {
2237 return is_in_reserved(p) && _hrm.is_available(addr_to_region((HeapWord*)p));
2238 }
2239
2240 // Iteration functions.
2241
2242 // Iterates an ObjectClosure over all objects within a HeapRegion.
2243
2244 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2245 ObjectClosure* _cl;
2246 public:
2247 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2248 bool do_heap_region(HeapRegion* r) {
2249 if (!r->is_continues_humongous()) {
2250 r->object_iterate(_cl);
2251 }
2252 return false;
2253 }
2254 };
2255
2256 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2257 IterateObjectClosureRegionClosure blk(cl);
2258 heap_region_iterate(&blk);
2259 }
2260
2261 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2262 private:
2263 G1CollectedHeap* _heap;
2264 HeapRegionClaimer _claimer;
2265
2266 public:
2267 G1ParallelObjectIterator(uint thread_num) :
2268 _heap(G1CollectedHeap::heap()),
2269 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2270
2271 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2272 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2273 }
2274 };
2275
2276 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2277 return new G1ParallelObjectIterator(thread_num);
2278 }
2279
2280 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2281 IterateObjectClosureRegionClosure blk(cl);
2282 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2283 }
2284
2285 void G1CollectedHeap::keep_alive(oop obj) {
2286 G1BarrierSet::enqueue_preloaded(obj);
2287 }
2288
2289 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2290 _hrm.iterate(cl);
2291 }
2292
2293 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2294 HeapRegionClaimer *hrclaimer,
2295 uint worker_id) const {
2296 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2297 }
2298
2299 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2300 HeapRegionClaimer *hrclaimer) const {
2301 _hrm.par_iterate(cl, hrclaimer, 0);
2302 }
2303
2304 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2305 _collection_set.iterate(cl);
2306 }
2307
2308 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2309 HeapRegionClaimer* hr_claimer,
2310 uint worker_id) {
2311 _collection_set.par_iterate(cl, hr_claimer, worker_id);
2312 }
2313
2314 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2315 HeapRegionClaimer* hr_claimer,
2316 uint worker_id) {
2317 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2318 }
2319
2320 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2321 HeapRegionClaimer* hr_claimer,
2322 const uint regions[],
2323 size_t length,
2324 uint worker_id) const {
2325 assert_at_safepoint();
2326 if (length == 0) {
2327 return;
2328 }
2329 uint total_workers = workers()->active_workers();
2330
2331 size_t start_pos = (worker_id * length) / total_workers;
2332 size_t cur_pos = start_pos;
2333
2334 do {
2335 uint region_idx = regions[cur_pos];
2336 if (hr_claimer == NULL || hr_claimer->claim_region(region_idx)) {
2337 HeapRegion* r = region_at(region_idx);
2338 bool result = cl->do_heap_region(r);
2339 guarantee(!result, "Must not cancel iteration");
2340 }
2341
2342 cur_pos++;
2343 if (cur_pos == length) {
2344 cur_pos = 0;
2345 }
2346 } while (cur_pos != start_pos);
2347 }
2348
2349 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2350 HeapRegion* hr = heap_region_containing(addr);
2351 return hr->block_start(addr);
2352 }
2353
2354 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2355 HeapRegion* hr = heap_region_containing(addr);
2356 return hr->block_is_obj(addr);
2357 }
2358
2359 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2360 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2361 }
2362
2363 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2364 return _eden.length() * HeapRegion::GrainBytes;
2365 }
2366
2367 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2368 // must be equal to the humongous object limit.
2369 size_t G1CollectedHeap::max_tlab_size() const {
2370 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2371 }
2372
2373 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2374 return _allocator->unsafe_max_tlab_alloc();
2375 }
2376
2377 size_t G1CollectedHeap::max_capacity() const {
2378 return max_regions() * HeapRegion::GrainBytes;
2379 }
2380
2381 void G1CollectedHeap::prepare_for_verify() {
2382 _verifier->prepare_for_verify();
2383 }
2384
2385 void G1CollectedHeap::verify(VerifyOption vo) {
2386 _verifier->verify(vo);
2387 }
2388
2389 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2390 return true;
2391 }
2392
2393 bool G1CollectedHeap::is_archived_object(oop object) const {
2394 return object != NULL && heap_region_containing(object)->is_archive();
2395 }
2396
2397 class PrintRegionClosure: public HeapRegionClosure {
2398 outputStream* _st;
2399 public:
2400 PrintRegionClosure(outputStream* st) : _st(st) {}
2401 bool do_heap_region(HeapRegion* r) {
2402 r->print_on(_st);
2403 return false;
2404 }
2405 };
2406
2407 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2408 const HeapRegion* hr,
2409 const VerifyOption vo) const {
2410 switch (vo) {
2411 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2412 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2413 default: ShouldNotReachHere();
2414 }
2415 return false; // keep some compilers happy
2416 }
2417
2418 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2419 const VerifyOption vo) const {
2420 switch (vo) {
2421 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2422 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2423 default: ShouldNotReachHere();
2424 }
2425 return false; // keep some compilers happy
2426 }
2427
2428 void G1CollectedHeap::print_heap_regions() const {
2429 LogTarget(Trace, gc, heap, region) lt;
2430 if (lt.is_enabled()) {
2431 LogStream ls(lt);
2432 print_regions_on(&ls);
2433 }
2434 }
2435
2436 void G1CollectedHeap::print_on(outputStream* st) const {
2437 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2438 st->print(" %-20s", "garbage-first heap");
2439 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2440 capacity()/K, heap_used/K);
2441 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2442 p2i(_hrm.reserved().start()),
2443 p2i(_hrm.reserved().end()));
2444 st->cr();
2445 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2446 uint young_regions = young_regions_count();
2447 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2448 (size_t) young_regions * HeapRegion::GrainBytes / K);
2449 uint survivor_regions = survivor_regions_count();
2450 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2451 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2452 st->cr();
2453 if (_numa->is_enabled()) {
2454 uint num_nodes = _numa->num_active_nodes();
2455 st->print(" remaining free region(s) on each NUMA node: ");
2456 const int* node_ids = _numa->node_ids();
2457 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2458 uint num_free_regions = _hrm.num_free_regions(node_index);
2459 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2460 }
2461 st->cr();
2462 }
2463 MetaspaceUtils::print_on(st);
2464 }
2465
2466 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2467 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2468 "HS=humongous(starts), HC=humongous(continues), "
2469 "CS=collection set, F=free, "
2470 "OA=open archive, CA=closed archive, "
2471 "TAMS=top-at-mark-start (previous, next)");
2472 PrintRegionClosure blk(st);
2473 heap_region_iterate(&blk);
2474 }
2475
2476 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2477 print_on(st);
2478
2479 // Print the per-region information.
2480 st->cr();
2481 print_regions_on(st);
2482 }
2483
2484 void G1CollectedHeap::print_on_error(outputStream* st) const {
2485 this->CollectedHeap::print_on_error(st);
2486
2487 if (_cm != NULL) {
2488 st->cr();
2489 _cm->print_on_error(st);
2490 }
2491 }
2492
2493 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2494 workers()->threads_do(tc);
2495 tc->do_thread(_cm_thread);
2496 _cm->threads_do(tc);
2497 _cr->threads_do(tc);
2498 tc->do_thread(_service_thread);
2499 }
2500
2501 void G1CollectedHeap::print_tracing_info() const {
2502 rem_set()->print_summary_info();
2503 concurrent_mark()->print_summary_info();
2504 }
2505
2506 #ifndef PRODUCT
2507 // Helpful for debugging RSet issues.
2508
2509 class PrintRSetsClosure : public HeapRegionClosure {
2510 private:
2511 const char* _msg;
2512 size_t _occupied_sum;
2513
2514 public:
2515 bool do_heap_region(HeapRegion* r) {
2516 HeapRegionRemSet* hrrs = r->rem_set();
2517 size_t occupied = hrrs->occupied();
2518 _occupied_sum += occupied;
2519
2520 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2521 if (occupied == 0) {
2522 tty->print_cr(" RSet is empty");
2523 } else {
2524 hrrs->print();
2525 }
2526 tty->print_cr("----------");
2527 return false;
2528 }
2529
2530 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2531 tty->cr();
2532 tty->print_cr("========================================");
2533 tty->print_cr("%s", msg);
2534 tty->cr();
2535 }
2536
2537 ~PrintRSetsClosure() {
2538 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2539 tty->print_cr("========================================");
2540 tty->cr();
2541 }
2542 };
2543
2544 void G1CollectedHeap::print_cset_rsets() {
2545 PrintRSetsClosure cl("Printing CSet RSets");
2546 collection_set_iterate_all(&cl);
2547 }
2548
2549 void G1CollectedHeap::print_all_rsets() {
2550 PrintRSetsClosure cl("Printing All RSets");;
2551 heap_region_iterate(&cl);
2552 }
2553 #endif // PRODUCT
2554
2555 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2556 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2557 }
2558
2559 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2560
2561 size_t eden_used_bytes = _eden.used_bytes();
2562 size_t survivor_used_bytes = _survivor.used_bytes();
2563 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2564
2565 size_t eden_capacity_bytes =
2566 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2567
2568 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2569 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2570 eden_capacity_bytes, survivor_used_bytes, num_regions());
2571 }
2572
2573 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2574 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2575 stats->unused(), stats->used(), stats->region_end_waste(),
2576 stats->regions_filled(), stats->direct_allocated(),
2577 stats->failure_used(), stats->failure_waste());
2578 }
2579
2580 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2581 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2582 gc_tracer->report_gc_heap_summary(when, heap_summary);
2583
2584 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2585 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2586 }
2587
2588 void G1CollectedHeap::gc_prologue(bool full) {
2589 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2590
2591 // Update common counters.
2592 increment_total_collections(full /* full gc */);
2593 if (full || collector_state()->in_concurrent_start_gc()) {
2594 increment_old_marking_cycles_started();
2595 }
2596 }
2597
2598 void G1CollectedHeap::gc_epilogue(bool full) {
2599 // Update common counters.
2600 if (full) {
2601 // Update the number of full collections that have been completed.
2602 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2603 }
2604
2605 #if COMPILER2_OR_JVMCI
2606 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2607 #endif
2608
2609 // We have just completed a GC. Update the soft reference
2610 // policy with the new heap occupancy
2611 Universe::heap()->update_capacity_and_used_at_gc();
2612
2613 _collection_pause_end = Ticks::now();
2614
2615 _free_segmented_array_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2616 &_collection_set_candidates_card_set_stats);
2617 }
2618
2619 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2620 return _hrm.uncommit_inactive_regions(region_limit);
2621 }
2622
2623 bool G1CollectedHeap::has_uncommittable_regions() {
2624 return _hrm.has_inactive_regions();
2625 }
2626
2627 void G1CollectedHeap::uncommit_regions_if_necessary() {
2628 if (has_uncommittable_regions()) {
2629 G1UncommitRegionTask::enqueue();
2630 }
2631 }
2632
2633 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2634 LogTarget(Trace, gc, heap, verify) lt;
2635
2636 if (lt.is_enabled()) {
2637 LogStream ls(lt);
2638 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2639 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2640 heap_region_iterate(&cl);
2641 }
2642 }
2643
2644 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2645 uint gc_count_before,
2646 bool* succeeded,
2647 GCCause::Cause gc_cause) {
2648 assert_heap_not_locked_and_not_at_safepoint();
2649 VM_G1CollectForAllocation op(word_size,
2650 gc_count_before,
2651 gc_cause,
2652 policy()->max_pause_time_ms());
2653 VMThread::execute(&op);
2654
2655 HeapWord* result = op.result();
2656 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2657 assert(result == NULL || ret_succeeded,
2658 "the result should be NULL if the VM did not succeed");
2659 *succeeded = ret_succeeded;
2660
2661 assert_heap_not_locked();
2662 return result;
2663 }
2664
2665 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2666 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2667
2668 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2669 if (concurrent_operation_is_full_mark) {
2670 _cm->post_concurrent_mark_start();
2671 _cm_thread->start_full_mark();
2672 } else {
2673 _cm->post_concurrent_undo_start();
2674 _cm_thread->start_undo_mark();
2675 }
2676 CGC_lock->notify();
2677 }
2678
2679 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2680 // We don't nominate objects with many remembered set entries, on
2681 // the assumption that such objects are likely still live.
2682 HeapRegionRemSet* rem_set = r->rem_set();
2683
2684 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2685 rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold) :
2686 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2687 }
2688
2689 #ifndef PRODUCT
2690 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2691 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2692 public:
2693 virtual bool do_heap_region(HeapRegion* r) {
2694 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2695 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2696 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2697 "Region %u remset tracking status (%s) different to region attribute (%s)",
2698 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2699 return false;
2700 }
2701 } cl;
2702 heap_region_iterate(&cl);
2703 }
2704 #endif
2705
2706 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2707 public:
2708 bool do_heap_region(HeapRegion* hr) {
2709 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2710 hr->verify_rem_set();
2711 }
2712 return false;
2713 }
2714 };
2715
2716 void G1CollectedHeap::start_new_collection_set() {
2717 double start = os::elapsedTime();
2718
2719 collection_set()->start_incremental_building();
2720
2721 clear_region_attr();
2722
2723 guarantee(_eden.length() == 0, "eden should have been cleared");
2724 policy()->transfer_survivors_to_cset(survivor());
2725
2726 // We redo the verification but now wrt to the new CSet which
2727 // has just got initialized after the previous CSet was freed.
2728 _cm->verify_no_collection_set_oops();
2729
2730 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2731 }
2732
2733 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2734 if (collector_state()->in_concurrent_start_gc()) {
2735 return G1HeapVerifier::G1VerifyConcurrentStart;
2736 } else if (collector_state()->in_young_only_phase()) {
2737 return G1HeapVerifier::G1VerifyYoungNormal;
2738 } else {
2739 return G1HeapVerifier::G1VerifyMixed;
2740 }
2741 }
2742
2743 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2744 if (!VerifyBeforeGC) {
2745 return;
2746 }
2747 Ticks start = Ticks::now();
2748 _verifier->prepare_for_verify();
2749 _verifier->verify_region_sets_optional();
2750 _verifier->verify_dirty_young_regions();
2751 if (VerifyRememberedSets) {
2752 log_info(gc, verify)("[Verifying RemSets before GC]");
2753 VerifyRegionRemSetClosure v_cl;
2754 heap_region_iterate(&v_cl);
2755 }
2756 _verifier->verify_before_gc(type);
2757 _verifier->check_bitmaps("GC Start");
2758 verify_numa_regions("GC Start");
2759 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2760 }
2761
2762 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2763 if (!VerifyAfterGC) {
2764 return;
2765 }
2766 Ticks start = Ticks::now();
2767 if (VerifyRememberedSets) {
2768 log_info(gc, verify)("[Verifying RemSets after GC]");
2769 VerifyRegionRemSetClosure v_cl;
2770 heap_region_iterate(&v_cl);
2771 }
2772 _verifier->verify_after_gc(type);
2773 _verifier->check_bitmaps("GC End");
2774 verify_numa_regions("GC End");
2775 _verifier->verify_region_sets_optional();
2776 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2777 }
2778
2779 void G1CollectedHeap::expand_heap_after_young_collection(){
2780 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2781 if (expand_bytes > 0) {
2782 // No need for an ergo logging here,
2783 // expansion_amount() does this when it returns a value > 0.
2784 double expand_ms = 0.0;
2785 if (!expand(expand_bytes, _workers, &expand_ms)) {
2786 // We failed to expand the heap. Cannot do anything about it.
2787 }
2788 phase_times()->record_expand_heap_time(expand_ms);
2789 }
2790 }
2791
2792 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2793 assert_at_safepoint_on_vm_thread();
2794 guarantee(!is_gc_active(), "collection is not reentrant");
2795
2796 if (GCLocker::check_active_before_gc()) {
2797 return false;
2798 }
2799
2800 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2801 return true;
2802 }
2803
2804 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2805 // This summary needs to be printed before incrementing total collections.
2806 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary", _g1h->total_collections());
2807 _g1h->print_heap_before_gc();
2808 _g1h->print_heap_regions();
2809 }
2810
2811 G1HeapPrinterMark::~G1HeapPrinterMark() {
2812 _g1h->policy()->print_age_table();
2813 _g1h->rem_set()->print_coarsen_stats();
2814 // We are at the end of the GC. Total collections has already been increased.
2815 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary", _g1h->total_collections() - 1);
2816
2817 _heap_transition.print();
2818 _g1h->print_heap_regions();
2819 _g1h->print_heap_after_gc();
2820 // Print NUMA statistics.
2821 _g1h->numa()->print_statistics();
2822 }
2823
2824 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2825 _timer(timer), _tracer(tracer) {
2826
2827 _timer->register_gc_start();
2828 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2829 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2830 }
2831
2832 G1JFRTracerMark::~G1JFRTracerMark() {
2833 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2834 _timer->register_gc_end();
2835 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2836 }
2837
2838 void G1CollectedHeap::prepare_tlabs_for_mutator() {
2839 Ticks start = Ticks::now();
2840
2841 _survivor_evac_stats.adjust_desired_plab_sz();
2842 _old_evac_stats.adjust_desired_plab_sz();
2843
2844 allocate_dummy_regions();
2845
2846 _allocator->init_mutator_alloc_regions();
2847
2848 resize_all_tlabs();
2849
2850 phase_times()->record_resize_tlab_time_ms((Ticks::now() - start).seconds() * 1000.0);
2851 }
2852
2853 void G1CollectedHeap::retire_tlabs() {
2854 ensure_parsability(true);
2855 }
2856
2857 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2858 ResourceMark rm;
2859
2860 IsGCActiveMark active_gc_mark;
2861 GCIdMark gc_id_mark;
2862 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2863
2864 GCTraceCPUTime tcpu;
2865
2866 _bytes_used_during_gc = 0;
2867
2868 policy()->decide_on_concurrent_start_pause();
2869 // Record whether this pause may need to trigger a concurrent operation. Later,
2870 // when we signal the G1ConcurrentMarkThread, the collector state has already
2871 // been reset for the next pause.
2872 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2873
2874 // Perform the collection.
2875 G1YoungCollector collector(gc_cause(), target_pause_time_ms);
2876 collector.collect();
2877
2878 // It should now be safe to tell the concurrent mark thread to start
2879 // without its logging output interfering with the logging output
2880 // that came from the pause.
2881 if (should_start_concurrent_mark_operation) {
2882 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2883 // thread(s) could be running concurrently with us. Make sure that anything
2884 // after this point does not assume that we are the only GC thread running.
2885 // Note: of course, the actual marking work will not start until the safepoint
2886 // itself is released in SuspendibleThreadSet::desynchronize().
2887 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2888 ConcurrentGCBreakpoints::notify_idle_to_active();
2889 }
2890 }
2891
2892 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
2893 bool class_unloading_occurred) {
2894 uint num_workers = workers()->active_workers();
2895 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred);
2896 workers()->run_task(&unlink_task);
2897 }
2898
2899 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2900 assert(obj != NULL, "must not be NULL");
2901 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2902 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2903 // may falsely indicate that this is not the case here: however the collection set only
2904 // contains old regions when concurrent mark is not running.
2905 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2906 }
2907
2908 void G1CollectedHeap::make_pending_list_reachable() {
2909 if (collector_state()->in_concurrent_start_gc()) {
2910 oop pll_head = Universe::reference_pending_list();
2911 if (pll_head != NULL) {
2912 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2913 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
2914 }
2915 }
2916 }
2917
2918 static bool do_humongous_object_logging() {
2919 return log_is_enabled(Debug, gc, humongous);
2920 }
2921
2922 bool G1CollectedHeap::should_do_eager_reclaim() const {
2923 // As eager reclaim logging also gives information about humongous objects in
2924 // the heap in general, always do the eager reclaim pass even without known
2925 // candidates.
2926 return (G1EagerReclaimHumongousObjects &&
2927 (has_humongous_reclaim_candidates() || do_humongous_object_logging()));
2928 }
2929
2930 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2931 _num_humongous_objects = num_humongous_total;
2932 _num_humongous_reclaim_candidates = num_humongous_candidates;
2933 }
2934
2935 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2936 G1CollectionSetCandidates* candidates = G1CollectedHeap::heap()->collection_set()->candidates();
2937 return candidates != NULL && candidates->num_remaining() > 0;
2938 }
2939
2940 void G1CollectedHeap::set_collection_set_candidates_stats(G1SegmentedArrayMemoryStats& stats) {
2941 _collection_set_candidates_card_set_stats = stats;
2942 }
2943
2944 void G1CollectedHeap::set_young_gen_card_set_stats(const G1SegmentedArrayMemoryStats& stats) {
2945 _young_gen_card_set_stats = stats;
2946 }
2947
2948 void G1CollectedHeap::record_obj_copy_mem_stats() {
2949 policy()->old_gen_alloc_tracker()->
2950 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2951
2952 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2953 create_g1_evac_summary(&_old_evac_stats));
2954 }
2955
2956 void G1CollectedHeap::clear_prev_bitmap_for_region(HeapRegion* hr) {
2957 MemRegion mr(hr->bottom(), hr->end());
2958 concurrent_mark()->clear_range_in_prev_bitmap(mr);
2959 }
2960
2961 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2962 assert(!hr->is_free(), "the region should not be free");
2963 assert(!hr->is_empty(), "the region should not be empty");
2964 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2965
2966 if (G1VerifyBitmaps) {
2967 clear_prev_bitmap_for_region(hr);
2968 }
2969
2970 // Clear the card counts for this region.
2971 // Note: we only need to do this if the region is not young
2972 // (since we don't refine cards in young regions).
2973 if (!hr->is_young()) {
2974 _hot_card_cache->reset_card_counts(hr);
2975 }
2976
2977 // Reset region metadata to allow reuse.
2978 hr->hr_clear(true /* clear_space */);
2979 _policy->remset_tracker()->update_at_free(hr);
2980
2981 if (free_list != NULL) {
2982 free_list->add_ordered(hr);
2983 }
2984 }
2985
2986 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2987 FreeRegionList* free_list) {
2988 assert(hr->is_humongous(), "this is only for humongous regions");
2989 hr->clear_humongous();
2990 free_region(hr, free_list);
2991 }
2992
2993 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2994 const uint archive_regions_removed,
2995 const uint humongous_regions_removed) {
2996 if (old_regions_removed > 0 || archive_regions_removed > 0 || humongous_regions_removed > 0) {
2997 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2998 _old_set.bulk_remove(old_regions_removed);
2999 _archive_set.bulk_remove(archive_regions_removed);
3000 _humongous_set.bulk_remove(humongous_regions_removed);
3001 }
3002
3003 }
3004
3005 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3006 assert(list != NULL, "list can't be null");
3007 if (!list->is_empty()) {
3008 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3009 _hrm.insert_list_into_free_list(list);
3010 }
3011 }
3012
3013 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3014 decrease_used(bytes);
3015 }
3016
3017 void G1CollectedHeap::clear_eden() {
3018 _eden.clear();
3019 }
3020
3021 void G1CollectedHeap::clear_collection_set() {
3022 collection_set()->clear();
3023 }
3024
3025 void G1CollectedHeap::rebuild_free_region_list() {
3026 Ticks start = Ticks::now();
3027 _hrm.rebuild_free_list(workers());
3028 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
3029 }
3030
3031 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
3032 public:
3033 virtual bool do_heap_region(HeapRegion* r) {
3034 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
3035 G1CollectedHeap::heap()->clear_region_attr(r);
3036 r->clear_young_index_in_cset();
3037 return false;
3038 }
3039 };
3040
3041 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
3042 G1AbandonCollectionSetClosure cl;
3043 collection_set_iterate_all(&cl);
3044
3045 collection_set->clear();
3046 collection_set->stop_incremental_building();
3047 }
3048
3049 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
3050 return _allocator->is_retained_old_region(hr);
3051 }
3052
3053 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
3054 _eden.add(hr);
3055 _policy->set_region_eden(hr);
3056 }
3057
3058 #ifdef ASSERT
3059
3060 class NoYoungRegionsClosure: public HeapRegionClosure {
3061 private:
3062 bool _success;
3063 public:
3064 NoYoungRegionsClosure() : _success(true) { }
3065 bool do_heap_region(HeapRegion* r) {
3066 if (r->is_young()) {
3067 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
3068 p2i(r->bottom()), p2i(r->end()));
3069 _success = false;
3070 }
3071 return false;
3072 }
3073 bool success() { return _success; }
3074 };
3075
3076 bool G1CollectedHeap::check_young_list_empty() {
3077 bool ret = (young_regions_count() == 0);
3078
3079 NoYoungRegionsClosure closure;
3080 heap_region_iterate(&closure);
3081 ret = ret && closure.success();
3082
3083 return ret;
3084 }
3085
3086 #endif // ASSERT
3087
3088 // Remove the given HeapRegion from the appropriate region set.
3089 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
3090 if (hr->is_archive()) {
3091 _archive_set.remove(hr);
3092 } else if (hr->is_humongous()) {
3093 _humongous_set.remove(hr);
3094 } else if (hr->is_old()) {
3095 _old_set.remove(hr);
3096 } else if (hr->is_young()) {
3097 // Note that emptying the eden and survivor lists is postponed and instead
3098 // done as the first step when rebuilding the regions sets again. The reason
3099 // for this is that during a full GC string deduplication needs to know if
3100 // a collected region was young or old when the full GC was initiated.
3101 hr->uninstall_surv_rate_group();
3102 } else {
3103 // We ignore free regions, we'll empty the free list afterwards.
3104 assert(hr->is_free(), "it cannot be another type");
3105 }
3106 }
3107
3108 void G1CollectedHeap::increase_used(size_t bytes) {
3109 _summary_bytes_used += bytes;
3110 }
3111
3112 void G1CollectedHeap::decrease_used(size_t bytes) {
3113 assert(_summary_bytes_used >= bytes,
3114 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
3115 _summary_bytes_used, bytes);
3116 _summary_bytes_used -= bytes;
3117 }
3118
3119 void G1CollectedHeap::set_used(size_t bytes) {
3120 _summary_bytes_used = bytes;
3121 }
3122
3123 class RebuildRegionSetsClosure : public HeapRegionClosure {
3124 private:
3125 bool _free_list_only;
3126
3127 HeapRegionSet* _old_set;
3128 HeapRegionSet* _archive_set;
3129 HeapRegionSet* _humongous_set;
3130
3131 HeapRegionManager* _hrm;
3132
3133 size_t _total_used;
3134
3135 public:
3136 RebuildRegionSetsClosure(bool free_list_only,
3137 HeapRegionSet* old_set,
3138 HeapRegionSet* archive_set,
3139 HeapRegionSet* humongous_set,
3140 HeapRegionManager* hrm) :
3141 _free_list_only(free_list_only), _old_set(old_set), _archive_set(archive_set),
3142 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
3143 assert(_hrm->num_free_regions() == 0, "pre-condition");
3144 if (!free_list_only) {
3145 assert(_old_set->is_empty(), "pre-condition");
3146 assert(_archive_set->is_empty(), "pre-condition");
3147 assert(_humongous_set->is_empty(), "pre-condition");
3148 }
3149 }
3150
3151 bool do_heap_region(HeapRegion* r) {
3152 if (r->is_empty()) {
3153 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
3154 // Add free regions to the free list
3155 r->set_free();
3156 _hrm->insert_into_free_list(r);
3157 } else if (!_free_list_only) {
3158 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
3159
3160 if (r->is_humongous()) {
3161 _humongous_set->add(r);
3162 } else if (r->is_archive()) {
3163 _archive_set->add(r);
3164 } else {
3165 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
3166 // We now move all (non-humongous, non-old, non-archive) regions to old gen,
3167 // and register them as such.
3168 r->move_to_old();
3169 _old_set->add(r);
3170 }
3171 _total_used += r->used();
3172 }
3173
3174 return false;
3175 }
3176
3177 size_t total_used() {
3178 return _total_used;
3179 }
3180 };
3181
3182 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
3183 assert_at_safepoint_on_vm_thread();
3184
3185 if (!free_list_only) {
3186 _eden.clear();
3187 _survivor.clear();
3188 }
3189
3190 RebuildRegionSetsClosure cl(free_list_only,
3191 &_old_set, &_archive_set, &_humongous_set,
3192 &_hrm);
3193 heap_region_iterate(&cl);
3194
3195 if (!free_list_only) {
3196 set_used(cl.total_used());
3197 assert(_archive_allocator == nullptr, "must be, should not contribute to used");
3198 }
3199 assert_used_and_recalculate_used_equal(this);
3200 }
3201
3202 // Methods for the mutator alloc region
3203
3204 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
3205 bool force,
3206 uint node_index) {
3207 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3208 bool should_allocate = policy()->should_allocate_mutator_region();
3209 if (force || should_allocate) {
3210 HeapRegion* new_alloc_region = new_region(word_size,
3211 HeapRegionType::Eden,
3212 false /* do_expand */,
3213 node_index);
3214 if (new_alloc_region != NULL) {
3215 set_region_short_lived_locked(new_alloc_region);
3216 _hr_printer.alloc(new_alloc_region, !should_allocate);
3217 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
3218 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3219 return new_alloc_region;
3220 }
3221 }
3222 return NULL;
3223 }
3224
3225 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
3226 size_t allocated_bytes) {
3227 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3228 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
3229
3230 collection_set()->add_eden_region(alloc_region);
3231 increase_used(allocated_bytes);
3232 _eden.add_used_bytes(allocated_bytes);
3233 _hr_printer.retire(alloc_region);
3234
3235 // We update the eden sizes here, when the region is retired,
3236 // instead of when it's allocated, since this is the point that its
3237 // used space has been recorded in _summary_bytes_used.
3238 monitoring_support()->update_eden_size();
3239 }
3240
3241 // Methods for the GC alloc regions
3242
3243 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
3244 if (dest.is_old()) {
3245 return true;
3246 } else {
3247 return survivor_regions_count() < policy()->max_survivor_regions();
3248 }
3249 }
3250
3251 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
3252 assert(FreeList_lock->owned_by_self(), "pre-condition");
3253
3254 if (!has_more_regions(dest)) {
3255 return NULL;
3256 }
3257
3258 HeapRegionType type;
3259 if (dest.is_young()) {
3260 type = HeapRegionType::Survivor;
3261 } else {
3262 type = HeapRegionType::Old;
3263 }
3264
3265 HeapRegion* new_alloc_region = new_region(word_size,
3266 type,
3267 true /* do_expand */,
3268 node_index);
3269
3270 if (new_alloc_region != NULL) {
3271 if (type.is_survivor()) {
3272 new_alloc_region->set_survivor();
3273 _survivor.add(new_alloc_region);
3274 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
3275 register_new_survivor_region_with_region_attr(new_alloc_region);
3276 } else {
3277 new_alloc_region->set_old();
3278 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
3279 }
3280 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3281 register_region_with_region_attr(new_alloc_region);
3282 _hr_printer.alloc(new_alloc_region);
3283 return new_alloc_region;
3284 }
3285 return NULL;
3286 }
3287
3288 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
3289 size_t allocated_bytes,
3290 G1HeapRegionAttr dest) {
3291 _bytes_used_during_gc += allocated_bytes;
3292 if (dest.is_old()) {
3293 old_set_add(alloc_region);
3294 } else {
3295 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
3296 _survivor.add_used_bytes(allocated_bytes);
3297 }
3298
3299 bool const during_im = collector_state()->in_concurrent_start_gc();
3300 if (during_im && allocated_bytes > 0) {
3301 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
3302 }
3303 _hr_printer.retire(alloc_region);
3304 }
3305
3306 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
3307 bool expanded = false;
3308 uint index = _hrm.find_highest_free(&expanded);
3309
3310 if (index != G1_NO_HRM_INDEX) {
3311 if (expanded) {
3312 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
3313 HeapRegion::GrainWords * HeapWordSize);
3314 }
3315 return _hrm.allocate_free_regions_starting_at(index, 1);
3316 }
3317 return NULL;
3318 }
3319
3320 void G1CollectedHeap::mark_evac_failure_object(const oop obj, uint worker_id) const {
3321 // All objects failing evacuation are live. What we'll do is
3322 // that we'll update the prev marking info so that they are
3323 // all under PTAMS and explicitly marked.
3324 _cm->par_mark_in_prev_bitmap(obj);
3325 }
3326
3327 // Optimized nmethod scanning
3328
3329 class RegisterNMethodOopClosure: public OopClosure {
3330 G1CollectedHeap* _g1h;
3331 nmethod* _nm;
3332
3333 public:
3334 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3335 _g1h(g1h), _nm(nm) {}
3336
3337 void do_oop(oop* p) {
3338 oop heap_oop = RawAccess<>::oop_load(p);
3339 if (!CompressedOops::is_null(heap_oop)) {
3340 oop obj = CompressedOops::decode_not_null(heap_oop);
3341 HeapRegion* hr = _g1h->heap_region_containing(obj);
3342 assert(!hr->is_continues_humongous(),
3343 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3344 " starting at " HR_FORMAT,
3345 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3346
3347 // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3348 hr->add_code_root_locked(_nm);
3349 }
3350 }
3351
3352 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3353 };
3354
3355 class UnregisterNMethodOopClosure: public OopClosure {
3356 G1CollectedHeap* _g1h;
3357 nmethod* _nm;
3358
3359 public:
3360 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3361 _g1h(g1h), _nm(nm) {}
3362
3363 void do_oop(oop* p) {
3364 oop heap_oop = RawAccess<>::oop_load(p);
3365 if (!CompressedOops::is_null(heap_oop)) {
3366 oop obj = CompressedOops::decode_not_null(heap_oop);
3367 HeapRegion* hr = _g1h->heap_region_containing(obj);
3368 assert(!hr->is_continues_humongous(),
3369 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3370 " starting at " HR_FORMAT,
3371 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3372
3373 hr->remove_code_root(_nm);
3374 }
3375 }
3376
3377 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3378 };
3379
3380 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3381 guarantee(nm != NULL, "sanity");
3382 RegisterNMethodOopClosure reg_cl(this, nm);
3383 nm->oops_do(®_cl);
3384 }
3385
3386 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3387 guarantee(nm != NULL, "sanity");
3388 UnregisterNMethodOopClosure reg_cl(this, nm);
3389 nm->oops_do(®_cl, true);
3390 }
3391
3392 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3393 if (evacuation_failed) {
3394 // Reset the G1EvacuationFailureALot counters and flags
3395 evac_failure_injector()->reset();
3396
3397 set_used(recalculate_used());
3398
3399 assert(_archive_allocator == nullptr, "must be, should not contribute to used");
3400 } else {
3401 // The "used" of the the collection set have already been subtracted
3402 // when they were freed. Add in the bytes used.
3403 increase_used(_bytes_used_during_gc);
3404 }
3405 }
3406
3407 void G1CollectedHeap::reset_hot_card_cache() {
3408 _hot_card_cache->reset_hot_cache();
3409 _hot_card_cache->set_use_cache(true);
3410 }
3411
3412 void G1CollectedHeap::purge_code_root_memory() {
3413 G1CodeRootSet::purge();
3414 }
3415
3416 class RebuildCodeRootClosure: public CodeBlobClosure {
3417 G1CollectedHeap* _g1h;
3418
3419 public:
3420 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3421 _g1h(g1h) {}
3422
3423 void do_code_blob(CodeBlob* cb) {
3424 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
3425 if (nm == NULL) {
3426 return;
3427 }
3428
3429 _g1h->register_nmethod(nm);
3430 }
3431 };
3432
3433 void G1CollectedHeap::rebuild_code_roots() {
3434 RebuildCodeRootClosure blob_cl(this);
3435 CodeCache::blobs_do(&blob_cl);
3436 }
3437
3438 void G1CollectedHeap::initialize_serviceability() {
3439 _monitoring_support->initialize_serviceability();
3440 }
3441
3442 MemoryUsage G1CollectedHeap::memory_usage() {
3443 return _monitoring_support->memory_usage();
3444 }
3445
3446 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3447 return _monitoring_support->memory_managers();
3448 }
3449
3450 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3451 return _monitoring_support->memory_pools();
3452 }
3453
3454 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3455 HeapRegion* region = heap_region_containing(start);
3456 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3457 }