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