1 /*
2 * Copyright (c) 2001, 2021, 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/g1CollectedHeap.inline.hpp"
36 #include "gc/g1/g1CollectionSet.hpp"
37 #include "gc/g1/g1CollectorState.hpp"
38 #include "gc/g1/g1ConcurrentRefine.hpp"
39 #include "gc/g1/g1ConcurrentRefineThread.hpp"
40 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
41 #include "gc/g1/g1DirtyCardQueue.hpp"
42 #include "gc/g1/g1EvacStats.inline.hpp"
43 #include "gc/g1/g1FullCollector.hpp"
44 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
45 #include "gc/g1/g1GCPhaseTimes.hpp"
46 #include "gc/g1/g1GCPauseType.hpp"
47 #include "gc/g1/g1HeapSizingPolicy.hpp"
48 #include "gc/g1/g1HeapTransition.hpp"
49 #include "gc/g1/g1HeapVerifier.hpp"
50 #include "gc/g1/g1HotCardCache.hpp"
51 #include "gc/g1/g1InitLogger.hpp"
52 #include "gc/g1/g1MemoryPool.hpp"
53 #include "gc/g1/g1OopClosures.inline.hpp"
54 #include "gc/g1/g1ParallelCleaning.hpp"
55 #include "gc/g1/g1ParScanThreadState.inline.hpp"
56 #include "gc/g1/g1PeriodicGCTask.hpp"
57 #include "gc/g1/g1Policy.hpp"
58 #include "gc/g1/g1RedirtyCardsQueue.hpp"
59 #include "gc/g1/g1RegionToSpaceMapper.hpp"
60 #include "gc/g1/g1RemSet.hpp"
61 #include "gc/g1/g1RootClosures.hpp"
62 #include "gc/g1/g1RootProcessor.hpp"
63 #include "gc/g1/g1SATBMarkQueueSet.hpp"
64 #include "gc/g1/g1ThreadLocalData.hpp"
65 #include "gc/g1/g1Trace.hpp"
66 #include "gc/g1/g1ServiceThread.hpp"
67 #include "gc/g1/g1UncommitRegionTask.hpp"
68 #include "gc/g1/g1VMOperations.hpp"
69 #include "gc/g1/g1YoungGCPostEvacuateTasks.hpp"
70 #include "gc/g1/heapRegion.inline.hpp"
71 #include "gc/g1/heapRegionRemSet.hpp"
72 #include "gc/g1/heapRegionSet.inline.hpp"
73 #include "gc/shared/concurrentGCBreakpoints.hpp"
74 #include "gc/shared/gcBehaviours.hpp"
75 #include "gc/shared/gcHeapSummary.hpp"
76 #include "gc/shared/gcId.hpp"
77 #include "gc/shared/gcLocker.hpp"
78 #include "gc/shared/gcTimer.hpp"
79 #include "gc/shared/gcTraceTime.inline.hpp"
80 #include "gc/shared/generationSpec.hpp"
81 #include "gc/shared/isGCActiveMark.hpp"
82 #include "gc/shared/locationPrinter.inline.hpp"
83 #include "gc/shared/oopStorageParState.hpp"
84 #include "gc/shared/preservedMarks.inline.hpp"
85 #include "gc/shared/suspendibleThreadSet.hpp"
86 #include "gc/shared/referenceProcessor.inline.hpp"
87 #include "gc/shared/taskTerminator.hpp"
88 #include "gc/shared/taskqueue.inline.hpp"
89 #include "gc/shared/tlab_globals.hpp"
90 #include "gc/shared/weakProcessor.inline.hpp"
91 #include "gc/shared/workerPolicy.hpp"
92 #include "logging/log.hpp"
93 #include "memory/allocation.hpp"
94 #include "memory/iterator.hpp"
95 #include "memory/heapInspection.hpp"
96 #include "memory/metaspaceUtils.hpp"
97 #include "memory/resourceArea.hpp"
98 #include "memory/universe.hpp"
99 #include "oops/access.inline.hpp"
100 #include "oops/compressedOops.inline.hpp"
101 #include "oops/oop.inline.hpp"
102 #include "runtime/atomic.hpp"
103 #include "runtime/handles.inline.hpp"
104 #include "runtime/init.hpp"
105 #include "runtime/java.hpp"
106 #include "runtime/orderAccess.hpp"
107 #include "runtime/threadSMR.hpp"
108 #include "runtime/vmThread.hpp"
109 #include "utilities/align.hpp"
110 #include "utilities/autoRestore.hpp"
111 #include "utilities/bitMap.inline.hpp"
112 #include "utilities/globalDefinitions.hpp"
113 #include "utilities/stack.inline.hpp"
114
115 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
116
117 // INVARIANTS/NOTES
118 //
119 // All allocation activity covered by the G1CollectedHeap interface is
120 // serialized by acquiring the HeapLock. This happens in mem_allocate
121 // and allocate_new_tlab, which are the "entry" points to the
122 // allocation code from the rest of the JVM. (Note that this does not
123 // apply to TLAB allocation, which is not part of this interface: it
124 // is done by clients of this interface.)
125
126 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
127 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
128 }
129
130 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
131 // The from card cache is not the memory that is actually committed. So we cannot
132 // take advantage of the zero_filled parameter.
133 reset_from_card_cache(start_idx, num_regions);
134 }
135
136 Tickspan G1CollectedHeap::run_task_timed(AbstractGangTask* task) {
137 Ticks start = Ticks::now();
138 workers()->run_task(task);
139 return Ticks::now() - start;
140 }
141
142 void G1CollectedHeap::run_batch_task(G1BatchedGangTask* cl) {
143 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
144 cl->set_max_workers(num_workers);
145 workers()->run_task(cl, num_workers);
146 }
147
148 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
149 MemRegion mr) {
150 return new HeapRegion(hrs_index, bot(), mr);
151 }
152
153 // Private methods.
154
155 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
156 HeapRegionType type,
157 bool do_expand,
158 uint node_index) {
159 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
160 "the only time we use this to allocate a humongous region is "
161 "when we are allocating a single humongous region");
162
163 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
164
165 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
166 // Currently, only attempts to allocate GC alloc regions set
167 // do_expand to true. So, we should only reach here during a
168 // safepoint. If this assumption changes we might have to
169 // reconsider the use of _expand_heap_after_alloc_failure.
170 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
171
172 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
173 word_size * HeapWordSize);
174
175 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
176 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
177 word_size * HeapWordSize);
178 if (expand_single_region(node_index)) {
179 // Given that expand_single_region() succeeded in expanding the heap, and we
180 // always expand the heap by an amount aligned to the heap
181 // region size, the free list should in theory not be empty.
182 // In either case allocate_free_region() will check for NULL.
183 res = _hrm.allocate_free_region(type, node_index);
184 } else {
185 _expand_heap_after_alloc_failure = false;
186 }
187 }
188 return res;
189 }
190
191 HeapWord*
192 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
193 uint num_regions,
194 size_t word_size) {
195 assert(first_hr != NULL, "pre-condition");
196 assert(is_humongous(word_size), "word_size should be humongous");
197 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
198
199 // Index of last region in the series.
200 uint first = first_hr->hrm_index();
201 uint last = first + num_regions - 1;
202
203 // We need to initialize the region(s) we just discovered. This is
204 // a bit tricky given that it can happen concurrently with
205 // refinement threads refining cards on these regions and
206 // potentially wanting to refine the BOT as they are scanning
207 // those cards (this can happen shortly after a cleanup; see CR
208 // 6991377). So we have to set up the region(s) carefully and in
209 // a specific order.
210
211 // The word size sum of all the regions we will allocate.
212 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
213 assert(word_size <= word_size_sum, "sanity");
214
215 // The passed in hr will be the "starts humongous" region. The header
216 // of the new object will be placed at the bottom of this region.
217 HeapWord* new_obj = first_hr->bottom();
218 // This will be the new top of the new object.
219 HeapWord* obj_top = new_obj + word_size;
220
221 // First, we need to zero the header of the space that we will be
222 // allocating. When we update top further down, some refinement
223 // threads might try to scan the region. By zeroing the header we
224 // ensure that any thread that will try to scan the region will
225 // come across the zero klass word and bail out.
226 //
227 // NOTE: It would not have been correct to have used
228 // CollectedHeap::fill_with_object() and make the space look like
229 // an int array. The thread that is doing the allocation will
230 // later update the object header to a potentially different array
231 // type and, for a very short period of time, the klass and length
232 // fields will be inconsistent. This could cause a refinement
233 // thread to calculate the object size incorrectly.
234 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
235
236 // Next, pad out the unused tail of the last region with filler
237 // objects, for improved usage accounting.
238 // How many words we use for filler objects.
239 size_t word_fill_size = word_size_sum - word_size;
240
241 // How many words memory we "waste" which cannot hold a filler object.
242 size_t words_not_fillable = 0;
243
244 if (word_fill_size >= min_fill_size()) {
245 fill_with_objects(obj_top, word_fill_size);
246 } else if (word_fill_size > 0) {
247 // We have space to fill, but we cannot fit an object there.
248 words_not_fillable = word_fill_size;
249 word_fill_size = 0;
250 }
251
252 // We will set up the first region as "starts humongous". This
253 // will also update the BOT covering all the regions to reflect
254 // that there is a single object that starts at the bottom of the
255 // first region.
256 first_hr->set_starts_humongous(obj_top, word_fill_size);
257 _policy->remset_tracker()->update_at_allocate(first_hr);
258 // Then, if there are any, we will set up the "continues
259 // humongous" regions.
260 HeapRegion* hr = NULL;
261 for (uint i = first + 1; i <= last; ++i) {
262 hr = region_at(i);
263 hr->set_continues_humongous(first_hr);
264 _policy->remset_tracker()->update_at_allocate(hr);
265 }
266
267 // Up to this point no concurrent thread would have been able to
268 // do any scanning on any region in this series. All the top
269 // fields still point to bottom, so the intersection between
270 // [bottom,top] and [card_start,card_end] will be empty. Before we
271 // update the top fields, we'll do a storestore to make sure that
272 // no thread sees the update to top before the zeroing of the
273 // object header and the BOT initialization.
274 OrderAccess::storestore();
275
276 // Now, we will update the top fields of the "continues humongous"
277 // regions except the last one.
278 for (uint i = first; i < last; ++i) {
279 hr = region_at(i);
280 hr->set_top(hr->end());
281 }
282
283 hr = region_at(last);
284 // If we cannot fit a filler object, we must set top to the end
285 // of the humongous object, otherwise we cannot iterate the heap
286 // and the BOT will not be complete.
287 hr->set_top(hr->end() - words_not_fillable);
288
289 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
290 "obj_top should be in last region");
291
292 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
293
294 assert(words_not_fillable == 0 ||
295 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
296 "Miscalculation in humongous allocation");
297
298 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
299
300 for (uint i = first; i <= last; ++i) {
301 hr = region_at(i);
302 _humongous_set.add(hr);
303 _hr_printer.alloc(hr);
304 }
305
306 return new_obj;
307 }
308
309 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
310 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
311 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
312 }
313
314 // If could fit into free regions w/o expansion, try.
315 // Otherwise, if can expand, do so.
316 // Otherwise, if using ex regions might help, try with ex given back.
317 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
318 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
319
320 _verifier->verify_region_sets_optional();
321
322 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
323
324 // Policy: First try to allocate a humongous object in the free list.
325 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
326 if (humongous_start == NULL) {
327 // Policy: We could not find enough regions for the humongous object in the
328 // free list. Look through the heap to find a mix of free and uncommitted regions.
329 // If so, expand the heap and allocate the humongous object.
330 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
331 if (humongous_start != NULL) {
332 // We managed to find a region by expanding the heap.
333 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
334 word_size * HeapWordSize);
335 policy()->record_new_heap_size(num_regions());
336 } else {
337 // Policy: Potentially trigger a defragmentation GC.
338 }
339 }
340
341 HeapWord* result = NULL;
342 if (humongous_start != NULL) {
343 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
344 assert(result != NULL, "it should always return a valid result");
345
346 // A successful humongous object allocation changes the used space
347 // information of the old generation so we need to recalculate the
348 // sizes and update the jstat counters here.
349 g1mm()->update_sizes();
350 }
351
352 _verifier->verify_region_sets_optional();
353
354 return result;
355 }
356
357 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
358 size_t requested_size,
359 size_t* actual_size) {
360 assert_heap_not_locked_and_not_at_safepoint();
361 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
362
363 return attempt_allocation(min_size, requested_size, actual_size);
364 }
365
366 HeapWord*
367 G1CollectedHeap::mem_allocate(size_t word_size,
368 bool* gc_overhead_limit_was_exceeded) {
369 assert_heap_not_locked_and_not_at_safepoint();
370
371 if (is_humongous(word_size)) {
372 return attempt_allocation_humongous(word_size);
373 }
374 size_t dummy = 0;
375 return attempt_allocation(word_size, word_size, &dummy);
376 }
377
378 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
379 ResourceMark rm; // For retrieving the thread names in log messages.
380
381 // Make sure you read the note in attempt_allocation_humongous().
382
383 assert_heap_not_locked_and_not_at_safepoint();
384 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
385 "be called for humongous allocation requests");
386
387 // We should only get here after the first-level allocation attempt
388 // (attempt_allocation()) failed to allocate.
389
390 // We will loop until a) we manage to successfully perform the
391 // allocation or b) we successfully schedule a collection which
392 // fails to perform the allocation. b) is the only case when we'll
393 // return NULL.
394 HeapWord* result = NULL;
395 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
396 bool should_try_gc;
397 bool preventive_collection_required = false;
398 uint gc_count_before;
399
400 {
401 MutexLocker x(Heap_lock);
402
403 // Now that we have the lock, we first retry the allocation in case another
404 // thread changed the region while we were waiting to acquire the lock.
405 size_t actual_size;
406 result = _allocator->attempt_allocation(word_size, word_size, &actual_size);
407 if (result != NULL) {
408 return result;
409 }
410
411 preventive_collection_required = policy()->preventive_collection_required(1);
412 if (!preventive_collection_required) {
413 // We've already attempted a lock-free allocation above, so we don't want to
414 // do it again. Let's jump straight to replacing the active region.
415 result = _allocator->attempt_allocation_using_new_region(word_size);
416 if (result != NULL) {
417 return result;
418 }
419
420 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
421 // This is different to when only GCLocker::needs_gc() is set: try to avoid
422 // waiting because the GCLocker is active to not wait too long.
423 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
424 // No need for an ergo message here, can_expand_young_list() does this when
425 // it returns true.
426 result = _allocator->attempt_allocation_force(word_size);
427 if (result != NULL) {
428 return result;
429 }
430 }
431 }
432
433 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
434 // the GCLocker initiated GC has been performed and then retry. This includes
435 // the case when the GC Locker is not active but has not been performed.
436 should_try_gc = !GCLocker::needs_gc();
437 // Read the GC count while still holding the Heap_lock.
438 gc_count_before = total_collections();
439 }
440
441 if (should_try_gc) {
442 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
443 : GCCause::_g1_inc_collection_pause;
444 bool succeeded;
445 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
446 if (result != NULL) {
447 assert(succeeded, "only way to get back a non-NULL result");
448 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
449 Thread::current()->name(), p2i(result));
450 return result;
451 }
452
453 if (succeeded) {
454 // We successfully scheduled a collection which failed to allocate. No
455 // point in trying to allocate further. We'll just return NULL.
456 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
457 SIZE_FORMAT " words", Thread::current()->name(), word_size);
458 return NULL;
459 }
460 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
461 Thread::current()->name(), word_size);
462 } else {
463 // Failed to schedule a collection.
464 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
465 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
466 SIZE_FORMAT " words", Thread::current()->name(), word_size);
467 return NULL;
468 }
469 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
470 // The GCLocker is either active or the GCLocker initiated
471 // GC has not yet been performed. Stall until it is and
472 // then retry the allocation.
473 GCLocker::stall_until_clear();
474 gclocker_retry_count += 1;
475 }
476
477 // We can reach here if we were unsuccessful in scheduling a
478 // collection (because another thread beat us to it) or if we were
479 // stalled due to the GC locker. In either can we should retry the
480 // allocation attempt in case another thread successfully
481 // performed a collection and reclaimed enough space. We do the
482 // first attempt (without holding the Heap_lock) here and the
483 // follow-on attempt will be at the start of the next loop
484 // iteration (after taking the Heap_lock).
485 size_t dummy = 0;
486 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
487 if (result != NULL) {
488 return result;
489 }
490
491 // Give a warning if we seem to be looping forever.
492 if ((QueuedAllocationWarningCount > 0) &&
493 (try_count % QueuedAllocationWarningCount == 0)) {
494 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
495 Thread::current()->name(), try_count, word_size);
496 }
497 }
498
499 ShouldNotReachHere();
500 return NULL;
501 }
502
503 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
504 assert_at_safepoint_on_vm_thread();
505 if (_archive_allocator == NULL) {
506 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
507 }
508 }
509
510 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
511 // Allocations in archive regions cannot be of a size that would be considered
512 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
513 // may be different at archive-restore time.
514 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
515 }
516
517 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
518 assert_at_safepoint_on_vm_thread();
519 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
520 if (is_archive_alloc_too_large(word_size)) {
521 return NULL;
522 }
523 return _archive_allocator->archive_mem_allocate(word_size);
524 }
525
526 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
527 size_t end_alignment_in_bytes) {
528 assert_at_safepoint_on_vm_thread();
529 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
530
531 // Call complete_archive to do the real work, filling in the MemRegion
532 // array with the archive regions.
533 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
534 delete _archive_allocator;
535 _archive_allocator = NULL;
536 }
537
538 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
539 assert(ranges != NULL, "MemRegion array NULL");
540 assert(count != 0, "No MemRegions provided");
541 MemRegion reserved = _hrm.reserved();
542 for (size_t i = 0; i < count; i++) {
543 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
544 return false;
545 }
546 }
547 return true;
548 }
549
550 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
551 size_t count,
552 bool open) {
553 assert(!is_init_completed(), "Expect to be called at JVM init time");
554 assert(ranges != NULL, "MemRegion array NULL");
555 assert(count != 0, "No MemRegions provided");
556 MutexLocker x(Heap_lock);
557
558 MemRegion reserved = _hrm.reserved();
559 HeapWord* prev_last_addr = NULL;
560 HeapRegion* prev_last_region = NULL;
561
562 // Temporarily disable pretouching of heap pages. This interface is used
563 // when mmap'ing archived heap data in, so pre-touching is wasted.
564 FlagSetting fs(AlwaysPreTouch, false);
565
566 // For each specified MemRegion range, allocate the corresponding G1
567 // regions and mark them as archive regions. We expect the ranges
568 // in ascending starting address order, without overlap.
569 for (size_t i = 0; i < count; i++) {
570 MemRegion curr_range = ranges[i];
571 HeapWord* start_address = curr_range.start();
572 size_t word_size = curr_range.word_size();
573 HeapWord* last_address = curr_range.last();
574 size_t commits = 0;
575
576 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
577 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
578 p2i(start_address), p2i(last_address));
579 guarantee(start_address > prev_last_addr,
580 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
581 p2i(start_address), p2i(prev_last_addr));
582 prev_last_addr = last_address;
583
584 // Check for ranges that start in the same G1 region in which the previous
585 // range ended, and adjust the start address so we don't try to allocate
586 // the same region again. If the current range is entirely within that
587 // region, skip it, just adjusting the recorded top.
588 HeapRegion* start_region = _hrm.addr_to_region(start_address);
589 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
590 start_address = start_region->end();
591 if (start_address > last_address) {
592 increase_used(word_size * HeapWordSize);
593 start_region->set_top(last_address + 1);
594 continue;
595 }
596 start_region->set_top(start_address);
597 curr_range = MemRegion(start_address, last_address + 1);
598 start_region = _hrm.addr_to_region(start_address);
599 }
600
601 // Perform the actual region allocation, exiting if it fails.
602 // Then note how much new space we have allocated.
603 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
604 return false;
605 }
606 increase_used(word_size * HeapWordSize);
607 if (commits != 0) {
608 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
609 HeapRegion::GrainWords * HeapWordSize * commits);
610
611 }
612
613 // Mark each G1 region touched by the range as archive, add it to
614 // the old set, and set top.
615 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
616 HeapRegion* last_region = _hrm.addr_to_region(last_address);
617 prev_last_region = last_region;
618
619 while (curr_region != NULL) {
620 assert(curr_region->is_empty() && !curr_region->is_pinned(),
621 "Region already in use (index %u)", curr_region->hrm_index());
622 if (open) {
623 curr_region->set_open_archive();
624 } else {
625 curr_region->set_closed_archive();
626 }
627 _hr_printer.alloc(curr_region);
628 _archive_set.add(curr_region);
629 HeapWord* top;
630 HeapRegion* next_region;
631 if (curr_region != last_region) {
632 top = curr_region->end();
633 next_region = _hrm.next_region_in_heap(curr_region);
634 } else {
635 top = last_address + 1;
636 next_region = NULL;
637 }
638 curr_region->set_top(top);
639 curr_region = next_region;
640 }
641 }
642 return true;
643 }
644
645 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
646 assert(!is_init_completed(), "Expect to be called at JVM init time");
647 assert(ranges != NULL, "MemRegion array NULL");
648 assert(count != 0, "No MemRegions provided");
649 MemRegion reserved = _hrm.reserved();
650 HeapWord *prev_last_addr = NULL;
651 HeapRegion* prev_last_region = NULL;
652
653 // For each MemRegion, create filler objects, if needed, in the G1 regions
654 // that contain the address range. The address range actually within the
655 // MemRegion will not be modified. That is assumed to have been initialized
656 // elsewhere, probably via an mmap of archived heap data.
657 MutexLocker x(Heap_lock);
658 for (size_t i = 0; i < count; i++) {
659 HeapWord* start_address = ranges[i].start();
660 HeapWord* last_address = ranges[i].last();
661
662 assert(reserved.contains(start_address) && reserved.contains(last_address),
663 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
664 p2i(start_address), p2i(last_address));
665 assert(start_address > prev_last_addr,
666 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
667 p2i(start_address), p2i(prev_last_addr));
668
669 HeapRegion* start_region = _hrm.addr_to_region(start_address);
670 HeapRegion* last_region = _hrm.addr_to_region(last_address);
671 HeapWord* bottom_address = start_region->bottom();
672
673 // Check for a range beginning in the same region in which the
674 // previous one ended.
675 if (start_region == prev_last_region) {
676 bottom_address = prev_last_addr + 1;
677 }
678
679 // Verify that the regions were all marked as archive regions by
680 // alloc_archive_regions.
681 HeapRegion* curr_region = start_region;
682 while (curr_region != NULL) {
683 guarantee(curr_region->is_archive(),
684 "Expected archive region at index %u", curr_region->hrm_index());
685 if (curr_region != last_region) {
686 curr_region = _hrm.next_region_in_heap(curr_region);
687 } else {
688 curr_region = NULL;
689 }
690 }
691
692 prev_last_addr = last_address;
693 prev_last_region = last_region;
694
695 // Fill the memory below the allocated range with dummy object(s),
696 // if the region bottom does not match the range start, or if the previous
697 // range ended within the same G1 region, and there is a gap.
698 assert(start_address >= bottom_address, "bottom address should not be greater than start address");
699 if (start_address > bottom_address) {
700 size_t fill_size = pointer_delta(start_address, bottom_address);
701 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
702 increase_used(fill_size * HeapWordSize);
703 }
704 }
705 }
706
707 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
708 size_t desired_word_size,
709 size_t* actual_word_size) {
710 assert_heap_not_locked_and_not_at_safepoint();
711 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
712 "be called for humongous allocation requests");
713
714 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
715
716 if (result == NULL) {
717 *actual_word_size = desired_word_size;
718 result = attempt_allocation_slow(desired_word_size);
719 }
720
721 assert_heap_not_locked();
722 if (result != NULL) {
723 assert(*actual_word_size != 0, "Actual size must have been set here");
724 dirty_young_block(result, *actual_word_size);
725 } else {
726 *actual_word_size = 0;
727 }
728
729 return result;
730 }
731
732 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion* ranges, size_t count) {
733 assert(!is_init_completed(), "Expect to be called at JVM init time");
734 assert(ranges != NULL, "MemRegion array NULL");
735 assert(count != 0, "No MemRegions provided");
736
737 HeapWord* st = ranges[0].start();
738 HeapWord* last = ranges[count-1].last();
739 HeapRegion* hr_st = _hrm.addr_to_region(st);
740 HeapRegion* hr_last = _hrm.addr_to_region(last);
741
742 HeapRegion* hr_curr = hr_st;
743 while (hr_curr != NULL) {
744 hr_curr->update_bot();
745 if (hr_curr != hr_last) {
746 hr_curr = _hrm.next_region_in_heap(hr_curr);
747 } else {
748 hr_curr = NULL;
749 }
750 }
751 }
752
753 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
754 assert(!is_init_completed(), "Expect to be called at JVM init time");
755 assert(ranges != NULL, "MemRegion array NULL");
756 assert(count != 0, "No MemRegions provided");
757 MemRegion reserved = _hrm.reserved();
758 HeapWord* prev_last_addr = NULL;
759 HeapRegion* prev_last_region = NULL;
760 size_t size_used = 0;
761 uint shrink_count = 0;
762
763 // For each Memregion, free the G1 regions that constitute it, and
764 // notify mark-sweep that the range is no longer to be considered 'archive.'
765 MutexLocker x(Heap_lock);
766 for (size_t i = 0; i < count; i++) {
767 HeapWord* start_address = ranges[i].start();
768 HeapWord* last_address = ranges[i].last();
769
770 assert(reserved.contains(start_address) && reserved.contains(last_address),
771 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
772 p2i(start_address), p2i(last_address));
773 assert(start_address > prev_last_addr,
774 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
775 p2i(start_address), p2i(prev_last_addr));
776 size_used += ranges[i].byte_size();
777 prev_last_addr = last_address;
778
779 HeapRegion* start_region = _hrm.addr_to_region(start_address);
780 HeapRegion* last_region = _hrm.addr_to_region(last_address);
781
782 // Check for ranges that start in the same G1 region in which the previous
783 // range ended, and adjust the start address so we don't try to free
784 // the same region again. If the current range is entirely within that
785 // region, skip it.
786 if (start_region == prev_last_region) {
787 start_address = start_region->end();
788 if (start_address > last_address) {
789 continue;
790 }
791 start_region = _hrm.addr_to_region(start_address);
792 }
793 prev_last_region = last_region;
794
795 // After verifying that each region was marked as an archive region by
796 // alloc_archive_regions, set it free and empty and uncommit it.
797 HeapRegion* curr_region = start_region;
798 while (curr_region != NULL) {
799 guarantee(curr_region->is_archive(),
800 "Expected archive region at index %u", curr_region->hrm_index());
801 uint curr_index = curr_region->hrm_index();
802 _archive_set.remove(curr_region);
803 curr_region->set_free();
804 curr_region->set_top(curr_region->bottom());
805 if (curr_region != last_region) {
806 curr_region = _hrm.next_region_in_heap(curr_region);
807 } else {
808 curr_region = NULL;
809 }
810
811 _hrm.shrink_at(curr_index, 1);
812 shrink_count++;
813 }
814 }
815
816 if (shrink_count != 0) {
817 log_debug(gc, ergo, heap)("Attempt heap shrinking (archive regions). Total size: " SIZE_FORMAT "B",
818 HeapRegion::GrainWords * HeapWordSize * shrink_count);
819 // Explicit uncommit.
820 uncommit_regions(shrink_count);
821 }
822 decrease_used(size_used);
823 }
824
825 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
826 ResourceMark rm; // For retrieving the thread names in log messages.
827
828 // The structure of this method has a lot of similarities to
829 // attempt_allocation_slow(). The reason these two were not merged
830 // into a single one is that such a method would require several "if
831 // allocation is not humongous do this, otherwise do that"
832 // conditional paths which would obscure its flow. In fact, an early
833 // version of this code did use a unified method which was harder to
834 // follow and, as a result, it had subtle bugs that were hard to
835 // track down. So keeping these two methods separate allows each to
836 // be more readable. It will be good to keep these two in sync as
837 // much as possible.
838
839 assert_heap_not_locked_and_not_at_safepoint();
840 assert(is_humongous(word_size), "attempt_allocation_humongous() "
841 "should only be called for humongous allocations");
842
843 // Humongous objects can exhaust the heap quickly, so we should check if we
844 // need to start a marking cycle at each humongous object allocation. We do
845 // the check before we do the actual allocation. The reason for doing it
846 // before the allocation is that we avoid having to keep track of the newly
847 // allocated memory while we do a GC.
848 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
849 word_size)) {
850 collect(GCCause::_g1_humongous_allocation);
851 }
852
853 // We will loop until a) we manage to successfully perform the
854 // allocation or b) we successfully schedule a collection which
855 // fails to perform the allocation. b) is the only case when we'll
856 // return NULL.
857 HeapWord* result = NULL;
858 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
859 bool should_try_gc;
860 bool preventive_collection_required = false;
861 uint gc_count_before;
862
863
864 {
865 MutexLocker x(Heap_lock);
866
867 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
868 preventive_collection_required = policy()->preventive_collection_required((uint)size_in_regions);
869 if (!preventive_collection_required) {
870 // Given that humongous objects are not allocated in young
871 // regions, we'll first try to do the allocation without doing a
872 // collection hoping that there's enough space in the heap.
873 result = humongous_obj_allocate(word_size);
874 if (result != NULL) {
875 policy()->old_gen_alloc_tracker()->
876 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
877 return result;
878 }
879 }
880
881 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
882 // the GCLocker initiated GC has been performed and then retry. This includes
883 // the case when the GC Locker is not active but has not been performed.
884 should_try_gc = !GCLocker::needs_gc();
885 // Read the GC count while still holding the Heap_lock.
886 gc_count_before = total_collections();
887 }
888
889 if (should_try_gc) {
890 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
891 : GCCause::_g1_humongous_allocation;
892 bool succeeded;
893 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
894 if (result != NULL) {
895 assert(succeeded, "only way to get back a non-NULL result");
896 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
897 Thread::current()->name(), p2i(result));
898 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
899 policy()->old_gen_alloc_tracker()->
900 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
901 return result;
902 }
903
904 if (succeeded) {
905 // We successfully scheduled a collection which failed to allocate. No
906 // point in trying to allocate further. We'll just return NULL.
907 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
908 SIZE_FORMAT " words", Thread::current()->name(), word_size);
909 return NULL;
910 }
911 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
912 Thread::current()->name(), word_size);
913 } else {
914 // Failed to schedule a collection.
915 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
916 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
917 SIZE_FORMAT " words", Thread::current()->name(), word_size);
918 return NULL;
919 }
920 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
921 // The GCLocker is either active or the GCLocker initiated
922 // GC has not yet been performed. Stall until it is and
923 // then retry the allocation.
924 GCLocker::stall_until_clear();
925 gclocker_retry_count += 1;
926 }
927
928
929 // We can reach here if we were unsuccessful in scheduling a
930 // collection (because another thread beat us to it) or if we were
931 // stalled due to the GC locker. In either can we should retry the
932 // allocation attempt in case another thread successfully
933 // performed a collection and reclaimed enough space.
934 // Humongous object allocation always needs a lock, so we wait for the retry
935 // in the next iteration of the loop, unlike for the regular iteration case.
936 // Give a warning if we seem to be looping forever.
937
938 if ((QueuedAllocationWarningCount > 0) &&
939 (try_count % QueuedAllocationWarningCount == 0)) {
940 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
941 Thread::current()->name(), try_count, word_size);
942 }
943 }
944
945 ShouldNotReachHere();
946 return NULL;
947 }
948
949 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
950 bool expect_null_mutator_alloc_region) {
951 assert_at_safepoint_on_vm_thread();
952 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
953 "the current alloc region was unexpectedly found to be non-NULL");
954
955 if (!is_humongous(word_size)) {
956 return _allocator->attempt_allocation_locked(word_size);
957 } else {
958 HeapWord* result = humongous_obj_allocate(word_size);
959 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
960 collector_state()->set_initiate_conc_mark_if_possible(true);
961 }
962 return result;
963 }
964
965 ShouldNotReachHere();
966 }
967
968 class PostCompactionPrinterClosure: public HeapRegionClosure {
969 private:
970 G1HRPrinter* _hr_printer;
971 public:
972 bool do_heap_region(HeapRegion* hr) {
973 assert(!hr->is_young(), "not expecting to find young regions");
974 _hr_printer->post_compaction(hr);
975 return false;
976 }
977
978 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
979 : _hr_printer(hr_printer) { }
980 };
981
982 void G1CollectedHeap::print_hrm_post_compaction() {
983 if (_hr_printer.is_active()) {
984 PostCompactionPrinterClosure cl(hr_printer());
985 heap_region_iterate(&cl);
986 }
987 }
988
989 void G1CollectedHeap::abort_concurrent_cycle() {
990 // If we start the compaction before the CM threads finish
991 // scanning the root regions we might trip them over as we'll
992 // be moving objects / updating references. So let's wait until
993 // they are done. By telling them to abort, they should complete
994 // early.
995 _cm->root_regions()->abort();
996 _cm->root_regions()->wait_until_scan_finished();
997
998 // Disable discovery and empty the discovered lists
999 // for the CM ref processor.
1000 _ref_processor_cm->disable_discovery();
1001 _ref_processor_cm->abandon_partial_discovery();
1002 _ref_processor_cm->verify_no_references_recorded();
1003
1004 // Abandon current iterations of concurrent marking and concurrent
1005 // refinement, if any are in progress.
1006 concurrent_mark()->concurrent_cycle_abort();
1007 }
1008
1009 void G1CollectedHeap::prepare_heap_for_full_collection() {
1010 // Make sure we'll choose a new allocation region afterwards.
1011 _allocator->release_mutator_alloc_regions();
1012 _allocator->abandon_gc_alloc_regions();
1013
1014 // We may have added regions to the current incremental collection
1015 // set between the last GC or pause and now. We need to clear the
1016 // incremental collection set and then start rebuilding it afresh
1017 // after this full GC.
1018 abandon_collection_set(collection_set());
1019
1020 _hrm.remove_all_free_regions();
1021 }
1022
1023 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1024 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1025 assert_used_and_recalculate_used_equal(this);
1026 _verifier->verify_region_sets_optional();
1027 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1028 _verifier->check_bitmaps("Full GC Start");
1029 }
1030
1031 void G1CollectedHeap::prepare_heap_for_mutators() {
1032 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1033 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1034 DEBUG_ONLY(MetaspaceUtils::verify();)
1035
1036 // Prepare heap for normal collections.
1037 assert(num_free_regions() == 0, "we should not have added any free regions");
1038 rebuild_region_sets(false /* free_list_only */);
1039 abort_refinement();
1040 resize_heap_if_necessary();
1041 uncommit_regions_if_necessary();
1042
1043 // Rebuild the strong code root lists for each region
1044 rebuild_strong_code_roots();
1045
1046 // Purge code root memory
1047 purge_code_root_memory();
1048
1049 // Start a new incremental collection set for the next pause
1050 start_new_collection_set();
1051
1052 _allocator->init_mutator_alloc_regions();
1053
1054 // Post collection state updates.
1055 MetaspaceGC::compute_new_size();
1056 }
1057
1058 void G1CollectedHeap::abort_refinement() {
1059 if (_hot_card_cache->use_cache()) {
1060 _hot_card_cache->reset_hot_cache();
1061 }
1062
1063 // Discard all remembered set updates and reset refinement statistics.
1064 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1065 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1066 "DCQS should be empty");
1067 concurrent_refine()->get_and_reset_refinement_stats();
1068 }
1069
1070 void G1CollectedHeap::verify_after_full_collection() {
1071 _hrm.verify_optional();
1072 _verifier->verify_region_sets_optional();
1073 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1074
1075 // This call implicitly verifies that the next bitmap is clear after Full GC.
1076 _verifier->check_bitmaps("Full GC End");
1077
1078 // At this point there should be no regions in the
1079 // entire heap tagged as young.
1080 assert(check_young_list_empty(), "young list should be empty at this point");
1081
1082 // Note: since we've just done a full GC, concurrent
1083 // marking is no longer active. Therefore we need not
1084 // re-enable reference discovery for the CM ref processor.
1085 // That will be done at the start of the next marking cycle.
1086 // We also know that the STW processor should no longer
1087 // discover any new references.
1088 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1089 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1090 _ref_processor_stw->verify_no_references_recorded();
1091 _ref_processor_cm->verify_no_references_recorded();
1092 }
1093
1094 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1095 // Post collection logging.
1096 // We should do this after we potentially resize the heap so
1097 // that all the COMMIT / UNCOMMIT events are generated before
1098 // the compaction events.
1099 print_hrm_post_compaction();
1100 heap_transition->print();
1101 print_heap_after_gc();
1102 print_heap_regions();
1103 }
1104
1105 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1106 bool clear_all_soft_refs,
1107 bool do_maximum_compaction) {
1108 assert_at_safepoint_on_vm_thread();
1109
1110 if (GCLocker::check_active_before_gc()) {
1111 // Full GC was not completed.
1112 return false;
1113 }
1114
1115 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1116 soft_ref_policy()->should_clear_all_soft_refs();
1117
1118 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs, do_maximum_compaction);
1119 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1120
1121 collector.prepare_collection();
1122 collector.collect();
1123 collector.complete_collection();
1124
1125 // Full collection was successfully completed.
1126 return true;
1127 }
1128
1129 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1130 // Currently, there is no facility in the do_full_collection(bool) API to notify
1131 // the caller that the collection did not succeed (e.g., because it was locked
1132 // out by the GC locker). So, right now, we'll ignore the return value.
1133 // When clear_all_soft_refs is set we want to do a maximum compaction
1134 // not leaving any dead wood.
1135 bool do_maximum_compaction = clear_all_soft_refs;
1136 bool dummy = do_full_collection(true, /* explicit_gc */
1137 clear_all_soft_refs,
1138 do_maximum_compaction);
1139 }
1140
1141 bool G1CollectedHeap::upgrade_to_full_collection() {
1142 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1143 log_info(gc, ergo)("Attempting full compaction clearing soft references");
1144 bool success = do_full_collection(false /* explicit gc */,
1145 true /* clear_all_soft_refs */,
1146 false /* do_maximum_compaction */);
1147 // do_full_collection only fails if blocked by GC locker and that can't
1148 // be the case here since we only call this when already completed one gc.
1149 assert(success, "invariant");
1150 return success;
1151 }
1152
1153 void G1CollectedHeap::resize_heap_if_necessary() {
1154 assert_at_safepoint_on_vm_thread();
1155
1156 bool should_expand;
1157 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1158
1159 if (resize_amount == 0) {
1160 return;
1161 } else if (should_expand) {
1162 expand(resize_amount, _workers);
1163 } else {
1164 shrink(resize_amount);
1165 }
1166 }
1167
1168 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1169 bool do_gc,
1170 bool maximum_compaction,
1171 bool expect_null_mutator_alloc_region,
1172 bool* gc_succeeded) {
1173 *gc_succeeded = true;
1174 // Let's attempt the allocation first.
1175 HeapWord* result =
1176 attempt_allocation_at_safepoint(word_size,
1177 expect_null_mutator_alloc_region);
1178 if (result != NULL) {
1179 return result;
1180 }
1181
1182 // In a G1 heap, we're supposed to keep allocation from failing by
1183 // incremental pauses. Therefore, at least for now, we'll favor
1184 // expansion over collection. (This might change in the future if we can
1185 // do something smarter than full collection to satisfy a failed alloc.)
1186 result = expand_and_allocate(word_size);
1187 if (result != NULL) {
1188 return result;
1189 }
1190
1191 if (do_gc) {
1192 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1193 // Expansion didn't work, we'll try to do a Full GC.
1194 // If maximum_compaction is set we clear all soft references and don't
1195 // allow any dead wood to be left on the heap.
1196 if (maximum_compaction) {
1197 log_info(gc, ergo)("Attempting maximum full compaction clearing soft references");
1198 } else {
1199 log_info(gc, ergo)("Attempting full compaction");
1200 }
1201 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1202 maximum_compaction /* clear_all_soft_refs */ ,
1203 maximum_compaction /* do_maximum_compaction */);
1204 }
1205
1206 return NULL;
1207 }
1208
1209 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1210 bool* succeeded) {
1211 assert_at_safepoint_on_vm_thread();
1212
1213 // Attempts to allocate followed by Full GC.
1214 HeapWord* result =
1215 satisfy_failed_allocation_helper(word_size,
1216 true, /* do_gc */
1217 false, /* maximum_collection */
1218 false, /* expect_null_mutator_alloc_region */
1219 succeeded);
1220
1221 if (result != NULL || !*succeeded) {
1222 return result;
1223 }
1224
1225 // Attempts to allocate followed by Full GC that will collect all soft references.
1226 result = satisfy_failed_allocation_helper(word_size,
1227 true, /* do_gc */
1228 true, /* maximum_collection */
1229 true, /* expect_null_mutator_alloc_region */
1230 succeeded);
1231
1232 if (result != NULL || !*succeeded) {
1233 return result;
1234 }
1235
1236 // Attempts to allocate, no GC
1237 result = satisfy_failed_allocation_helper(word_size,
1238 false, /* do_gc */
1239 false, /* maximum_collection */
1240 true, /* expect_null_mutator_alloc_region */
1241 succeeded);
1242
1243 if (result != NULL) {
1244 return result;
1245 }
1246
1247 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1248 "Flag should have been handled and cleared prior to this point");
1249
1250 // What else? We might try synchronous finalization later. If the total
1251 // space available is large enough for the allocation, then a more
1252 // complete compaction phase than we've tried so far might be
1253 // appropriate.
1254 return NULL;
1255 }
1256
1257 // Attempting to expand the heap sufficiently
1258 // to support an allocation of the given "word_size". If
1259 // successful, perform the allocation and return the address of the
1260 // allocated block, or else "NULL".
1261
1262 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1263 assert_at_safepoint_on_vm_thread();
1264
1265 _verifier->verify_region_sets_optional();
1266
1267 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1268 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1269 word_size * HeapWordSize);
1270
1271
1272 if (expand(expand_bytes, _workers)) {
1273 _hrm.verify_optional();
1274 _verifier->verify_region_sets_optional();
1275 return attempt_allocation_at_safepoint(word_size,
1276 false /* expect_null_mutator_alloc_region */);
1277 }
1278 return NULL;
1279 }
1280
1281 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1282 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1283 aligned_expand_bytes = align_up(aligned_expand_bytes,
1284 HeapRegion::GrainBytes);
1285
1286 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1287 expand_bytes, aligned_expand_bytes);
1288
1289 if (is_maximal_no_gc()) {
1290 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1291 return false;
1292 }
1293
1294 double expand_heap_start_time_sec = os::elapsedTime();
1295 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1296 assert(regions_to_expand > 0, "Must expand by at least one region");
1297
1298 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1299 if (expand_time_ms != NULL) {
1300 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1301 }
1302
1303 if (expanded_by > 0) {
1304 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1305 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1306 policy()->record_new_heap_size(num_regions());
1307 } else {
1308 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1309
1310 // The expansion of the virtual storage space was unsuccessful.
1311 // Let's see if it was because we ran out of swap.
1312 if (G1ExitOnExpansionFailure &&
1313 _hrm.available() >= regions_to_expand) {
1314 // We had head room...
1315 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1316 }
1317 }
1318 return regions_to_expand > 0;
1319 }
1320
1321 bool G1CollectedHeap::expand_single_region(uint node_index) {
1322 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1323
1324 if (expanded_by == 0) {
1325 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1326 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1327 return false;
1328 }
1329
1330 policy()->record_new_heap_size(num_regions());
1331 return true;
1332 }
1333
1334 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1335 size_t aligned_shrink_bytes =
1336 ReservedSpace::page_align_size_down(shrink_bytes);
1337 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1338 HeapRegion::GrainBytes);
1339 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1340
1341 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1342 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1343
1344 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",
1345 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1346 if (num_regions_removed > 0) {
1347 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1348 policy()->record_new_heap_size(num_regions());
1349 } else {
1350 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1351 }
1352 }
1353
1354 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1355 _verifier->verify_region_sets_optional();
1356
1357 // We should only reach here at the end of a Full GC or during Remark which
1358 // means we should not not be holding to any GC alloc regions. The method
1359 // below will make sure of that and do any remaining clean up.
1360 _allocator->abandon_gc_alloc_regions();
1361
1362 // Instead of tearing down / rebuilding the free lists here, we
1363 // could instead use the remove_all_pending() method on free_list to
1364 // remove only the ones that we need to remove.
1365 _hrm.remove_all_free_regions();
1366 shrink_helper(shrink_bytes);
1367 rebuild_region_sets(true /* free_list_only */);
1368
1369 _hrm.verify_optional();
1370 _verifier->verify_region_sets_optional();
1371 }
1372
1373 class OldRegionSetChecker : public HeapRegionSetChecker {
1374 public:
1375 void check_mt_safety() {
1376 // Master Old Set MT safety protocol:
1377 // (a) If we're at a safepoint, operations on the master old set
1378 // should be invoked:
1379 // - by the VM thread (which will serialize them), or
1380 // - by the GC workers while holding the FreeList_lock, if we're
1381 // at a safepoint for an evacuation pause (this lock is taken
1382 // anyway when an GC alloc region is retired so that a new one
1383 // is allocated from the free list), or
1384 // - by the GC workers while holding the OldSets_lock, if we're at a
1385 // safepoint for a cleanup pause.
1386 // (b) If we're not at a safepoint, operations on the master old set
1387 // should be invoked while holding the Heap_lock.
1388
1389 if (SafepointSynchronize::is_at_safepoint()) {
1390 guarantee(Thread::current()->is_VM_thread() ||
1391 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1392 "master old set MT safety protocol at a safepoint");
1393 } else {
1394 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1395 }
1396 }
1397 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1398 const char* get_description() { return "Old Regions"; }
1399 };
1400
1401 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1402 public:
1403 void check_mt_safety() {
1404 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1405 "May only change archive regions during initialization or safepoint.");
1406 }
1407 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1408 const char* get_description() { return "Archive Regions"; }
1409 };
1410
1411 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1412 public:
1413 void check_mt_safety() {
1414 // Humongous Set MT safety protocol:
1415 // (a) If we're at a safepoint, operations on the master humongous
1416 // set should be invoked by either the VM thread (which will
1417 // serialize them) or by the GC workers while holding the
1418 // OldSets_lock.
1419 // (b) If we're not at a safepoint, operations on the master
1420 // humongous set should be invoked while holding the Heap_lock.
1421
1422 if (SafepointSynchronize::is_at_safepoint()) {
1423 guarantee(Thread::current()->is_VM_thread() ||
1424 OldSets_lock->owned_by_self(),
1425 "master humongous set MT safety protocol at a safepoint");
1426 } else {
1427 guarantee(Heap_lock->owned_by_self(),
1428 "master humongous set MT safety protocol outside a safepoint");
1429 }
1430 }
1431 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1432 const char* get_description() { return "Humongous Regions"; }
1433 };
1434
1435 G1CollectedHeap::G1CollectedHeap() :
1436 CollectedHeap(),
1437 _service_thread(NULL),
1438 _periodic_gc_task(NULL),
1439 _workers(NULL),
1440 _card_table(NULL),
1441 _collection_pause_end(Ticks::now()),
1442 _soft_ref_policy(),
1443 _old_set("Old Region Set", new OldRegionSetChecker()),
1444 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1445 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1446 _bot(NULL),
1447 _listener(),
1448 _numa(G1NUMA::create()),
1449 _hrm(),
1450 _allocator(NULL),
1451 _verifier(NULL),
1452 _summary_bytes_used(0),
1453 _bytes_used_during_gc(0),
1454 _archive_allocator(NULL),
1455 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1456 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1457 _expand_heap_after_alloc_failure(true),
1458 _g1mm(NULL),
1459 _humongous_reclaim_candidates(),
1460 _num_humongous_objects(0),
1461 _num_humongous_reclaim_candidates(0),
1462 _hr_printer(),
1463 _collector_state(),
1464 _old_marking_cycles_started(0),
1465 _old_marking_cycles_completed(0),
1466 _eden(),
1467 _survivor(),
1468 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1469 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1470 _policy(new G1Policy(_gc_timer_stw)),
1471 _heap_sizing_policy(NULL),
1472 _collection_set(this, _policy),
1473 _hot_card_cache(NULL),
1474 _rem_set(NULL),
1475 _cm(NULL),
1476 _cm_thread(NULL),
1477 _cr(NULL),
1478 _task_queues(NULL),
1479 _num_regions_failed_evacuation(0),
1480 _regions_failed_evacuation(NULL),
1481 _evacuation_failed_info_array(NULL),
1482 _preserved_marks_set(true /* in_c_heap */),
1483 #ifndef PRODUCT
1484 _evacuation_failure_alot_for_current_gc(false),
1485 _evacuation_failure_alot_gc_number(0),
1486 _evacuation_failure_alot_count(0),
1487 #endif
1488 _ref_processor_stw(NULL),
1489 _is_alive_closure_stw(this),
1490 _is_subject_to_discovery_stw(this),
1491 _ref_processor_cm(NULL),
1492 _is_alive_closure_cm(this),
1493 _is_subject_to_discovery_cm(this),
1494 _region_attr() {
1495
1496 _verifier = new G1HeapVerifier(this);
1497
1498 _allocator = new G1Allocator(this);
1499
1500 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1501
1502 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1503
1504 // Override the default _filler_array_max_size so that no humongous filler
1505 // objects are created.
1506 _filler_array_max_size = _humongous_object_threshold_in_words;
1507
1508 uint n_queues = ParallelGCThreads;
1509 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1510
1511 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1512
1513 for (uint i = 0; i < n_queues; i++) {
1514 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1515 q->initialize();
1516 _task_queues->register_queue(i, q);
1517 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1518 }
1519
1520 // Initialize the G1EvacuationFailureALot counters and flags.
1521 NOT_PRODUCT(reset_evacuation_should_fail();)
1522 _gc_tracer_stw->initialize();
1523
1524 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1525 }
1526
1527 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1528 size_t size,
1529 size_t translation_factor) {
1530 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1531 // Allocate a new reserved space, preferring to use large pages.
1532 ReservedSpace rs(size, preferred_page_size);
1533 size_t page_size = rs.page_size();
1534 G1RegionToSpaceMapper* result =
1535 G1RegionToSpaceMapper::create_mapper(rs,
1536 size,
1537 page_size,
1538 HeapRegion::GrainBytes,
1539 translation_factor,
1540 mtGC);
1541
1542 os::trace_page_sizes_for_requested_size(description,
1543 size,
1544 page_size,
1545 preferred_page_size,
1546 rs.base(),
1547 rs.size());
1548
1549 return result;
1550 }
1551
1552 jint G1CollectedHeap::initialize_concurrent_refinement() {
1553 jint ecode = JNI_OK;
1554 _cr = G1ConcurrentRefine::create(&ecode);
1555 return ecode;
1556 }
1557
1558 jint G1CollectedHeap::initialize_service_thread() {
1559 _service_thread = new G1ServiceThread();
1560 if (_service_thread->osthread() == NULL) {
1561 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1562 return JNI_ENOMEM;
1563 }
1564 return JNI_OK;
1565 }
1566
1567 jint G1CollectedHeap::initialize() {
1568
1569 // Necessary to satisfy locking discipline assertions.
1570
1571 MutexLocker x(Heap_lock);
1572
1573 // While there are no constraints in the GC code that HeapWordSize
1574 // be any particular value, there are multiple other areas in the
1575 // system which believe this to be true (e.g. oop->object_size in some
1576 // cases incorrectly returns the size in wordSize units rather than
1577 // HeapWordSize).
1578 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1579
1580 size_t init_byte_size = InitialHeapSize;
1581 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1582
1583 // Ensure that the sizes are properly aligned.
1584 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1585 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1586 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1587
1588 // Reserve the maximum.
1589
1590 // When compressed oops are enabled, the preferred heap base
1591 // is calculated by subtracting the requested size from the
1592 // 32Gb boundary and using the result as the base address for
1593 // heap reservation. If the requested size is not aligned to
1594 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1595 // into the ReservedHeapSpace constructor) then the actual
1596 // base of the reserved heap may end up differing from the
1597 // address that was requested (i.e. the preferred heap base).
1598 // If this happens then we could end up using a non-optimal
1599 // compressed oops mode.
1600
1601 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1602 HeapAlignment);
1603
1604 initialize_reserved_region(heap_rs);
1605
1606 // Create the barrier set for the entire reserved region.
1607 G1CardTable* ct = new G1CardTable(heap_rs.region());
1608 ct->initialize();
1609 G1BarrierSet* bs = new G1BarrierSet(ct);
1610 bs->initialize();
1611 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1612 BarrierSet::set_barrier_set(bs);
1613 _card_table = ct;
1614
1615 {
1616 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1617 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1618 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1619 }
1620
1621 // Create the hot card cache.
1622 _hot_card_cache = new G1HotCardCache(this);
1623
1624 // Create space mappers.
1625 size_t page_size = heap_rs.page_size();
1626 G1RegionToSpaceMapper* heap_storage =
1627 G1RegionToSpaceMapper::create_mapper(heap_rs,
1628 heap_rs.size(),
1629 page_size,
1630 HeapRegion::GrainBytes,
1631 1,
1632 mtJavaHeap);
1633 if(heap_storage == NULL) {
1634 vm_shutdown_during_initialization("Could not initialize G1 heap");
1635 return JNI_ERR;
1636 }
1637
1638 os::trace_page_sizes("Heap",
1639 MinHeapSize,
1640 reserved_byte_size,
1641 page_size,
1642 heap_rs.base(),
1643 heap_rs.size());
1644 heap_storage->set_mapping_changed_listener(&_listener);
1645
1646 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1647 G1RegionToSpaceMapper* bot_storage =
1648 create_aux_memory_mapper("Block Offset Table",
1649 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1650 G1BlockOffsetTable::heap_map_factor());
1651
1652 G1RegionToSpaceMapper* cardtable_storage =
1653 create_aux_memory_mapper("Card Table",
1654 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1655 G1CardTable::heap_map_factor());
1656
1657 G1RegionToSpaceMapper* card_counts_storage =
1658 create_aux_memory_mapper("Card Counts Table",
1659 G1CardCounts::compute_size(heap_rs.size() / HeapWordSize),
1660 G1CardCounts::heap_map_factor());
1661
1662 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1663 G1RegionToSpaceMapper* prev_bitmap_storage =
1664 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1665 G1RegionToSpaceMapper* next_bitmap_storage =
1666 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1667
1668 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1669 _card_table->initialize(cardtable_storage);
1670
1671 // Do later initialization work for concurrent refinement.
1672 _hot_card_cache->initialize(card_counts_storage);
1673
1674 // 6843694 - ensure that the maximum region index can fit
1675 // in the remembered set structures.
1676 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1677 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1678
1679 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1680 // start within the first card.
1681 guarantee(heap_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1682 G1FromCardCache::initialize(max_reserved_regions());
1683 // Also create a G1 rem set.
1684 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1685 _rem_set->initialize(max_reserved_regions());
1686
1687 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1688 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1689 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1690 "too many cards per region");
1691
1692 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1693
1694 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1695
1696 {
1697 size_t granularity = HeapRegion::GrainBytes;
1698
1699 _region_attr.initialize(reserved(), granularity);
1700 _humongous_reclaim_candidates.initialize(reserved(), granularity);
1701 }
1702
1703 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1704 true /* are_GC_task_threads */,
1705 false /* are_ConcurrentGC_threads */);
1706 if (_workers == NULL) {
1707 return JNI_ENOMEM;
1708 }
1709 _workers->initialize_workers();
1710
1711 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1712
1713 // Create the G1ConcurrentMark data structure and thread.
1714 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1715 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1716 _cm_thread = _cm->cm_thread();
1717
1718 // Now expand into the initial heap size.
1719 if (!expand(init_byte_size, _workers)) {
1720 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1721 return JNI_ENOMEM;
1722 }
1723
1724 // Perform any initialization actions delegated to the policy.
1725 policy()->init(this, &_collection_set);
1726
1727 jint ecode = initialize_concurrent_refinement();
1728 if (ecode != JNI_OK) {
1729 return ecode;
1730 }
1731
1732 ecode = initialize_service_thread();
1733 if (ecode != JNI_OK) {
1734 return ecode;
1735 }
1736
1737 // Initialize and schedule sampling task on service thread.
1738 _rem_set->initialize_sampling_task(service_thread());
1739
1740 // Create and schedule the periodic gc task on the service thread.
1741 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1742 _service_thread->register_task(_periodic_gc_task);
1743
1744 {
1745 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1746 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1747 dcqs.set_max_cards(concurrent_refine()->red_zone());
1748 }
1749
1750 // Here we allocate the dummy HeapRegion that is required by the
1751 // G1AllocRegion class.
1752 HeapRegion* dummy_region = _hrm.get_dummy_region();
1753
1754 // We'll re-use the same region whether the alloc region will
1755 // require BOT updates or not and, if it doesn't, then a non-young
1756 // region will complain that it cannot support allocations without
1757 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1758 dummy_region->set_eden();
1759 // Make sure it's full.
1760 dummy_region->set_top(dummy_region->end());
1761 G1AllocRegion::setup(this, dummy_region);
1762
1763 _allocator->init_mutator_alloc_regions();
1764
1765 // Do create of the monitoring and management support so that
1766 // values in the heap have been properly initialized.
1767 _g1mm = new G1MonitoringSupport(this);
1768
1769 _preserved_marks_set.init(ParallelGCThreads);
1770
1771 _collection_set.initialize(max_reserved_regions());
1772
1773 _regions_failed_evacuation = NEW_C_HEAP_ARRAY(volatile bool, max_regions(), mtGC);
1774
1775 G1InitLogger::print();
1776
1777 return JNI_OK;
1778 }
1779
1780 void G1CollectedHeap::stop() {
1781 // Stop all concurrent threads. We do this to make sure these threads
1782 // do not continue to execute and access resources (e.g. logging)
1783 // that are destroyed during shutdown.
1784 _cr->stop();
1785 _service_thread->stop();
1786 _cm_thread->stop();
1787 }
1788
1789 void G1CollectedHeap::safepoint_synchronize_begin() {
1790 SuspendibleThreadSet::synchronize();
1791 }
1792
1793 void G1CollectedHeap::safepoint_synchronize_end() {
1794 SuspendibleThreadSet::desynchronize();
1795 }
1796
1797 void G1CollectedHeap::post_initialize() {
1798 CollectedHeap::post_initialize();
1799 ref_processing_init();
1800 }
1801
1802 void G1CollectedHeap::ref_processing_init() {
1803 // Reference processing in G1 currently works as follows:
1804 //
1805 // * There are two reference processor instances. One is
1806 // used to record and process discovered references
1807 // during concurrent marking; the other is used to
1808 // record and process references during STW pauses
1809 // (both full and incremental).
1810 // * Both ref processors need to 'span' the entire heap as
1811 // the regions in the collection set may be dotted around.
1812 //
1813 // * For the concurrent marking ref processor:
1814 // * Reference discovery is enabled at concurrent start.
1815 // * Reference discovery is disabled and the discovered
1816 // references processed etc during remarking.
1817 // * Reference discovery is MT (see below).
1818 // * Reference discovery requires a barrier (see below).
1819 // * Reference processing may or may not be MT
1820 // (depending on the value of ParallelRefProcEnabled
1821 // and ParallelGCThreads).
1822 // * A full GC disables reference discovery by the CM
1823 // ref processor and abandons any entries on it's
1824 // discovered lists.
1825 //
1826 // * For the STW processor:
1827 // * Non MT discovery is enabled at the start of a full GC.
1828 // * Processing and enqueueing during a full GC is non-MT.
1829 // * During a full GC, references are processed after marking.
1830 //
1831 // * Discovery (may or may not be MT) is enabled at the start
1832 // of an incremental evacuation pause.
1833 // * References are processed near the end of a STW evacuation pause.
1834 // * For both types of GC:
1835 // * Discovery is atomic - i.e. not concurrent.
1836 // * Reference discovery will not need a barrier.
1837
1838 // Concurrent Mark ref processor
1839 _ref_processor_cm =
1840 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1841 ParallelGCThreads, // degree of mt processing
1842 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1843 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1844 false, // Reference discovery is not atomic
1845 &_is_alive_closure_cm); // is alive closure
1846
1847 // STW ref processor
1848 _ref_processor_stw =
1849 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1850 ParallelGCThreads, // degree of mt processing
1851 (ParallelGCThreads > 1), // mt discovery
1852 ParallelGCThreads, // degree of mt discovery
1853 true, // Reference discovery is atomic
1854 &_is_alive_closure_stw); // is alive closure
1855 }
1856
1857 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1858 return &_soft_ref_policy;
1859 }
1860
1861 size_t G1CollectedHeap::capacity() const {
1862 return _hrm.length() * HeapRegion::GrainBytes;
1863 }
1864
1865 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1866 return _hrm.total_free_bytes();
1867 }
1868
1869 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1870 _hot_card_cache->drain(cl, worker_id);
1871 }
1872
1873 // Computes the sum of the storage used by the various regions.
1874 size_t G1CollectedHeap::used() const {
1875 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1876 if (_archive_allocator != NULL) {
1877 result += _archive_allocator->used();
1878 }
1879 return result;
1880 }
1881
1882 size_t G1CollectedHeap::used_unlocked() const {
1883 return _summary_bytes_used;
1884 }
1885
1886 class SumUsedClosure: public HeapRegionClosure {
1887 size_t _used;
1888 public:
1889 SumUsedClosure() : _used(0) {}
1890 bool do_heap_region(HeapRegion* r) {
1891 _used += r->used();
1892 return false;
1893 }
1894 size_t result() { return _used; }
1895 };
1896
1897 size_t G1CollectedHeap::recalculate_used() const {
1898 SumUsedClosure blk;
1899 heap_region_iterate(&blk);
1900 return blk.result();
1901 }
1902
1903 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1904 switch (cause) {
1905 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1906 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1907 case GCCause::_wb_conc_mark: return true;
1908 default : return false;
1909 }
1910 }
1911
1912 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1913 switch (cause) {
1914 case GCCause::_g1_humongous_allocation: return true;
1915 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1916 case GCCause::_wb_breakpoint: return true;
1917 default: return is_user_requested_concurrent_full_gc(cause);
1918 }
1919 }
1920
1921 #ifndef PRODUCT
1922 void G1CollectedHeap::allocate_dummy_regions() {
1923 // Let's fill up most of the region
1924 size_t word_size = HeapRegion::GrainWords - 1024;
1925 // And as a result the region we'll allocate will be humongous.
1926 guarantee(is_humongous(word_size), "sanity");
1927
1928 // _filler_array_max_size is set to humongous object threshold
1929 // but temporarily change it to use CollectedHeap::fill_with_object().
1930 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1931
1932 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1933 // Let's use the existing mechanism for the allocation
1934 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1935 if (dummy_obj != NULL) {
1936 MemRegion mr(dummy_obj, word_size);
1937 CollectedHeap::fill_with_object(mr);
1938 } else {
1939 // If we can't allocate once, we probably cannot allocate
1940 // again. Let's get out of the loop.
1941 break;
1942 }
1943 }
1944 }
1945 #endif // !PRODUCT
1946
1947 void G1CollectedHeap::increment_old_marking_cycles_started() {
1948 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1949 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1950 "Wrong marking cycle count (started: %d, completed: %d)",
1951 _old_marking_cycles_started, _old_marking_cycles_completed);
1952
1953 _old_marking_cycles_started++;
1954 }
1955
1956 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1957 bool whole_heap_examined) {
1958 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1959
1960 // We assume that if concurrent == true, then the caller is a
1961 // concurrent thread that was joined the Suspendible Thread
1962 // Set. If there's ever a cheap way to check this, we should add an
1963 // assert here.
1964
1965 // Given that this method is called at the end of a Full GC or of a
1966 // concurrent cycle, and those can be nested (i.e., a Full GC can
1967 // interrupt a concurrent cycle), the number of full collections
1968 // completed should be either one (in the case where there was no
1969 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1970 // behind the number of full collections started.
1971
1972 // This is the case for the inner caller, i.e. a Full GC.
1973 assert(concurrent ||
1974 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1975 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1976 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1977 "is inconsistent with _old_marking_cycles_completed = %u",
1978 _old_marking_cycles_started, _old_marking_cycles_completed);
1979
1980 // This is the case for the outer caller, i.e. the concurrent cycle.
1981 assert(!concurrent ||
1982 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1983 "for outer caller (concurrent cycle): "
1984 "_old_marking_cycles_started = %u "
1985 "is inconsistent with _old_marking_cycles_completed = %u",
1986 _old_marking_cycles_started, _old_marking_cycles_completed);
1987
1988 _old_marking_cycles_completed += 1;
1989 if (whole_heap_examined) {
1990 // Signal that we have completed a visit to all live objects.
1991 record_whole_heap_examined_timestamp();
1992 }
1993
1994 // We need to clear the "in_progress" flag in the CM thread before
1995 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1996 // is set) so that if a waiter requests another System.gc() it doesn't
1997 // incorrectly see that a marking cycle is still in progress.
1998 if (concurrent) {
1999 _cm_thread->set_idle();
2000 }
2001
2002 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2003 // for a full GC to finish that their wait is over.
2004 ml.notify_all();
2005 }
2006
2007 void G1CollectedHeap::collect(GCCause::Cause cause) {
2008 try_collect(cause);
2009 }
2010
2011 // Return true if (x < y) with allowance for wraparound.
2012 static bool gc_counter_less_than(uint x, uint y) {
2013 return (x - y) > (UINT_MAX/2);
2014 }
2015
2016 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2017 // Macro so msg printing is format-checked.
2018 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2019 do { \
2020 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2021 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2022 ResourceMark rm; /* For thread name. */ \
2023 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2024 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2025 Thread::current()->name(), \
2026 GCCause::to_string(cause)); \
2027 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2028 } \
2029 } while (0)
2030
2031 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2032 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2033
2034 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2035 uint gc_counter,
2036 uint old_marking_started_before) {
2037 assert_heap_not_locked();
2038 assert(should_do_concurrent_full_gc(cause),
2039 "Non-concurrent cause %s", GCCause::to_string(cause));
2040
2041 for (uint i = 1; true; ++i) {
2042 // Try to schedule concurrent start evacuation pause that will
2043 // start a concurrent cycle.
2044 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2045 VM_G1TryInitiateConcMark op(gc_counter,
2046 cause,
2047 policy()->max_pause_time_ms());
2048 VMThread::execute(&op);
2049
2050 // Request is trivially finished.
2051 if (cause == GCCause::_g1_periodic_collection) {
2052 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2053 return op.gc_succeeded();
2054 }
2055
2056 // If VMOp skipped initiating concurrent marking cycle because
2057 // we're terminating, then we're done.
2058 if (op.terminating()) {
2059 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2060 return false;
2061 }
2062
2063 // Lock to get consistent set of values.
2064 uint old_marking_started_after;
2065 uint old_marking_completed_after;
2066 {
2067 MutexLocker ml(Heap_lock);
2068 // Update gc_counter for retrying VMOp if needed. Captured here to be
2069 // consistent with the values we use below for termination tests. If
2070 // a retry is needed after a possible wait, and another collection
2071 // occurs in the meantime, it will cause our retry to be skipped and
2072 // we'll recheck for termination with updated conditions from that
2073 // more recent collection. That's what we want, rather than having
2074 // our retry possibly perform an unnecessary collection.
2075 gc_counter = total_collections();
2076 old_marking_started_after = _old_marking_cycles_started;
2077 old_marking_completed_after = _old_marking_cycles_completed;
2078 }
2079
2080 if (cause == GCCause::_wb_breakpoint) {
2081 if (op.gc_succeeded()) {
2082 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2083 return true;
2084 }
2085 // When _wb_breakpoint there can't be another cycle or deferred.
2086 assert(!op.cycle_already_in_progress(), "invariant");
2087 assert(!op.whitebox_attached(), "invariant");
2088 // Concurrent cycle attempt might have been cancelled by some other
2089 // collection, so retry. Unlike other cases below, we want to retry
2090 // even if cancelled by a STW full collection, because we really want
2091 // to start a concurrent cycle.
2092 if (old_marking_started_before != old_marking_started_after) {
2093 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2094 old_marking_started_before = old_marking_started_after;
2095 }
2096 } else if (!GCCause::is_user_requested_gc(cause)) {
2097 // For an "automatic" (not user-requested) collection, we just need to
2098 // ensure that progress is made.
2099 //
2100 // Request is finished if any of
2101 // (1) the VMOp successfully performed a GC,
2102 // (2) a concurrent cycle was already in progress,
2103 // (3) whitebox is controlling concurrent cycles,
2104 // (4) a new cycle was started (by this thread or some other), or
2105 // (5) a Full GC was performed.
2106 // Cases (4) and (5) are detected together by a change to
2107 // _old_marking_cycles_started.
2108 //
2109 // Note that (1) does not imply (4). If we're still in the mixed
2110 // phase of an earlier concurrent collection, the request to make the
2111 // collection a concurrent start won't be honored. If we don't check for
2112 // both conditions we'll spin doing back-to-back collections.
2113 if (op.gc_succeeded() ||
2114 op.cycle_already_in_progress() ||
2115 op.whitebox_attached() ||
2116 (old_marking_started_before != old_marking_started_after)) {
2117 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2118 return true;
2119 }
2120 } else { // User-requested GC.
2121 // For a user-requested collection, we want to ensure that a complete
2122 // full collection has been performed before returning, but without
2123 // waiting for more than needed.
2124
2125 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2126 // new cycle was started. That's good, because it's not clear what we
2127 // should do otherwise. Trying again just does back to back GCs.
2128 // Can't wait for someone else to start a cycle. And returning fails
2129 // to meet the goal of ensuring a full collection was performed.
2130 assert(!op.gc_succeeded() ||
2131 (old_marking_started_before != old_marking_started_after),
2132 "invariant: succeeded %s, started before %u, started after %u",
2133 BOOL_TO_STR(op.gc_succeeded()),
2134 old_marking_started_before, old_marking_started_after);
2135
2136 // Request is finished if a full collection (concurrent or stw)
2137 // was started after this request and has completed, e.g.
2138 // started_before < completed_after.
2139 if (gc_counter_less_than(old_marking_started_before,
2140 old_marking_completed_after)) {
2141 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2142 return true;
2143 }
2144
2145 if (old_marking_started_after != old_marking_completed_after) {
2146 // If there is an in-progress cycle (possibly started by us), then
2147 // wait for that cycle to complete, e.g.
2148 // while completed_now < started_after.
2149 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2150 MonitorLocker ml(G1OldGCCount_lock);
2151 while (gc_counter_less_than(_old_marking_cycles_completed,
2152 old_marking_started_after)) {
2153 ml.wait();
2154 }
2155 // Request is finished if the collection we just waited for was
2156 // started after this request.
2157 if (old_marking_started_before != old_marking_started_after) {
2158 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2159 return true;
2160 }
2161 }
2162
2163 // If VMOp was successful then it started a new cycle that the above
2164 // wait &etc should have recognized as finishing this request. This
2165 // differs from a non-user-request, where gc_succeeded does not imply
2166 // a new cycle was started.
2167 assert(!op.gc_succeeded(), "invariant");
2168
2169 if (op.cycle_already_in_progress()) {
2170 // If VMOp failed because a cycle was already in progress, it
2171 // is now complete. But it didn't finish this user-requested
2172 // GC, so try again.
2173 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2174 continue;
2175 } else if (op.whitebox_attached()) {
2176 // If WhiteBox wants control, wait for notification of a state
2177 // change in the controller, then try again. Don't wait for
2178 // release of control, since collections may complete while in
2179 // control. Note: This won't recognize a STW full collection
2180 // while waiting; we can't wait on multiple monitors.
2181 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2182 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2183 if (ConcurrentGCBreakpoints::is_controlled()) {
2184 ml.wait();
2185 }
2186 continue;
2187 }
2188 }
2189
2190 // Collection failed and should be retried.
2191 assert(op.transient_failure(), "invariant");
2192
2193 if (GCLocker::is_active_and_needs_gc()) {
2194 // If GCLocker is active, wait until clear before retrying.
2195 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2196 GCLocker::stall_until_clear();
2197 }
2198
2199 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2200 }
2201 }
2202
2203 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2204 assert_heap_not_locked();
2205
2206 // Lock to get consistent set of values.
2207 uint gc_count_before;
2208 uint full_gc_count_before;
2209 uint old_marking_started_before;
2210 {
2211 MutexLocker ml(Heap_lock);
2212 gc_count_before = total_collections();
2213 full_gc_count_before = total_full_collections();
2214 old_marking_started_before = _old_marking_cycles_started;
2215 }
2216
2217 if (should_do_concurrent_full_gc(cause)) {
2218 return try_collect_concurrently(cause,
2219 gc_count_before,
2220 old_marking_started_before);
2221 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2222 // Indicate failure to be consistent with VMOp failure due to
2223 // another collection slipping in after our gc_count but before
2224 // our request is processed.
2225 return false;
2226 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2227 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2228
2229 // Schedule a standard evacuation pause. We're setting word_size
2230 // to 0 which means that we are not requesting a post-GC allocation.
2231 VM_G1CollectForAllocation op(0, /* word_size */
2232 gc_count_before,
2233 cause,
2234 policy()->max_pause_time_ms());
2235 VMThread::execute(&op);
2236 return op.gc_succeeded();
2237 } else {
2238 // Schedule a Full GC.
2239 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2240 VMThread::execute(&op);
2241 return op.gc_succeeded();
2242 }
2243 }
2244
2245 bool G1CollectedHeap::is_in(const void* p) const {
2246 return is_in_reserved(p) && _hrm.is_available(addr_to_region((HeapWord*)p));
2247 }
2248
2249 // Iteration functions.
2250
2251 // Iterates an ObjectClosure over all objects within a HeapRegion.
2252
2253 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2254 ObjectClosure* _cl;
2255 public:
2256 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2257 bool do_heap_region(HeapRegion* r) {
2258 if (!r->is_continues_humongous()) {
2259 r->object_iterate(_cl);
2260 }
2261 return false;
2262 }
2263 };
2264
2265 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2266 IterateObjectClosureRegionClosure blk(cl);
2267 heap_region_iterate(&blk);
2268 }
2269
2270 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2271 private:
2272 G1CollectedHeap* _heap;
2273 HeapRegionClaimer _claimer;
2274
2275 public:
2276 G1ParallelObjectIterator(uint thread_num) :
2277 _heap(G1CollectedHeap::heap()),
2278 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2279
2280 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2281 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2282 }
2283 };
2284
2285 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2286 return new G1ParallelObjectIterator(thread_num);
2287 }
2288
2289 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2290 IterateObjectClosureRegionClosure blk(cl);
2291 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2292 }
2293
2294 void G1CollectedHeap::keep_alive(oop obj) {
2295 G1BarrierSet::enqueue_preloaded(obj);
2296 }
2297
2298 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2299 _hrm.iterate(cl);
2300 }
2301
2302 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2303 HeapRegionClaimer *hrclaimer,
2304 uint worker_id) const {
2305 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2306 }
2307
2308 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2309 HeapRegionClaimer *hrclaimer) const {
2310 _hrm.par_iterate(cl, hrclaimer, 0);
2311 }
2312
2313 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2314 _collection_set.iterate(cl);
2315 }
2316
2317 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2318 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2319 }
2320
2321 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2322 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2323 }
2324
2325 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2326 HeapRegion* hr = heap_region_containing(addr);
2327 return hr->block_start(addr);
2328 }
2329
2330 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2331 HeapRegion* hr = heap_region_containing(addr);
2332 return hr->block_is_obj(addr);
2333 }
2334
2335 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2336 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2337 }
2338
2339 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2340 return _eden.length() * HeapRegion::GrainBytes;
2341 }
2342
2343 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2344 // must be equal to the humongous object limit.
2345 size_t G1CollectedHeap::max_tlab_size() const {
2346 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2347 }
2348
2349 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2350 return _allocator->unsafe_max_tlab_alloc();
2351 }
2352
2353 size_t G1CollectedHeap::max_capacity() const {
2354 return max_regions() * HeapRegion::GrainBytes;
2355 }
2356
2357 void G1CollectedHeap::prepare_for_verify() {
2358 _verifier->prepare_for_verify();
2359 }
2360
2361 void G1CollectedHeap::verify(VerifyOption vo) {
2362 _verifier->verify(vo);
2363 }
2364
2365 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2366 return true;
2367 }
2368
2369 bool G1CollectedHeap::is_archived_object(oop object) const {
2370 return object != NULL && heap_region_containing(object)->is_archive();
2371 }
2372
2373 class PrintRegionClosure: public HeapRegionClosure {
2374 outputStream* _st;
2375 public:
2376 PrintRegionClosure(outputStream* st) : _st(st) {}
2377 bool do_heap_region(HeapRegion* r) {
2378 r->print_on(_st);
2379 return false;
2380 }
2381 };
2382
2383 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2384 const HeapRegion* hr,
2385 const VerifyOption vo) const {
2386 switch (vo) {
2387 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2388 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2389 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2390 default: ShouldNotReachHere();
2391 }
2392 return false; // keep some compilers happy
2393 }
2394
2395 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2396 const VerifyOption vo) const {
2397 switch (vo) {
2398 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2399 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2400 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2401 default: ShouldNotReachHere();
2402 }
2403 return false; // keep some compilers happy
2404 }
2405
2406 void G1CollectedHeap::print_heap_regions() const {
2407 LogTarget(Trace, gc, heap, region) lt;
2408 if (lt.is_enabled()) {
2409 LogStream ls(lt);
2410 print_regions_on(&ls);
2411 }
2412 }
2413
2414 void G1CollectedHeap::print_on(outputStream* st) const {
2415 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2416 st->print(" %-20s", "garbage-first heap");
2417 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2418 capacity()/K, heap_used/K);
2419 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2420 p2i(_hrm.reserved().start()),
2421 p2i(_hrm.reserved().end()));
2422 st->cr();
2423 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2424 uint young_regions = young_regions_count();
2425 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2426 (size_t) young_regions * HeapRegion::GrainBytes / K);
2427 uint survivor_regions = survivor_regions_count();
2428 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2429 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2430 st->cr();
2431 if (_numa->is_enabled()) {
2432 uint num_nodes = _numa->num_active_nodes();
2433 st->print(" remaining free region(s) on each NUMA node: ");
2434 const int* node_ids = _numa->node_ids();
2435 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2436 uint num_free_regions = _hrm.num_free_regions(node_index);
2437 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2438 }
2439 st->cr();
2440 }
2441 MetaspaceUtils::print_on(st);
2442 }
2443
2444 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2445 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2446 "HS=humongous(starts), HC=humongous(continues), "
2447 "CS=collection set, F=free, "
2448 "OA=open archive, CA=closed archive, "
2449 "TAMS=top-at-mark-start (previous, next)");
2450 PrintRegionClosure blk(st);
2451 heap_region_iterate(&blk);
2452 }
2453
2454 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2455 print_on(st);
2456
2457 // Print the per-region information.
2458 st->cr();
2459 print_regions_on(st);
2460 }
2461
2462 void G1CollectedHeap::print_on_error(outputStream* st) const {
2463 this->CollectedHeap::print_on_error(st);
2464
2465 if (_cm != NULL) {
2466 st->cr();
2467 _cm->print_on_error(st);
2468 }
2469 }
2470
2471 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2472 workers()->threads_do(tc);
2473 tc->do_thread(_cm_thread);
2474 _cm->threads_do(tc);
2475 _cr->threads_do(tc);
2476 tc->do_thread(_service_thread);
2477 }
2478
2479 void G1CollectedHeap::print_tracing_info() const {
2480 rem_set()->print_summary_info();
2481 concurrent_mark()->print_summary_info();
2482 }
2483
2484 #ifndef PRODUCT
2485 // Helpful for debugging RSet issues.
2486
2487 class PrintRSetsClosure : public HeapRegionClosure {
2488 private:
2489 const char* _msg;
2490 size_t _occupied_sum;
2491
2492 public:
2493 bool do_heap_region(HeapRegion* r) {
2494 HeapRegionRemSet* hrrs = r->rem_set();
2495 size_t occupied = hrrs->occupied();
2496 _occupied_sum += occupied;
2497
2498 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2499 if (occupied == 0) {
2500 tty->print_cr(" RSet is empty");
2501 } else {
2502 hrrs->print();
2503 }
2504 tty->print_cr("----------");
2505 return false;
2506 }
2507
2508 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2509 tty->cr();
2510 tty->print_cr("========================================");
2511 tty->print_cr("%s", msg);
2512 tty->cr();
2513 }
2514
2515 ~PrintRSetsClosure() {
2516 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2517 tty->print_cr("========================================");
2518 tty->cr();
2519 }
2520 };
2521
2522 void G1CollectedHeap::print_cset_rsets() {
2523 PrintRSetsClosure cl("Printing CSet RSets");
2524 collection_set_iterate_all(&cl);
2525 }
2526
2527 void G1CollectedHeap::print_all_rsets() {
2528 PrintRSetsClosure cl("Printing All RSets");;
2529 heap_region_iterate(&cl);
2530 }
2531 #endif // PRODUCT
2532
2533 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2534 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2535 }
2536
2537 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2538
2539 size_t eden_used_bytes = _eden.used_bytes();
2540 size_t survivor_used_bytes = _survivor.used_bytes();
2541 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2542
2543 size_t eden_capacity_bytes =
2544 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2545
2546 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2547 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2548 eden_capacity_bytes, survivor_used_bytes, num_regions());
2549 }
2550
2551 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2552 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2553 stats->unused(), stats->used(), stats->region_end_waste(),
2554 stats->regions_filled(), stats->direct_allocated(),
2555 stats->failure_used(), stats->failure_waste());
2556 }
2557
2558 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2559 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2560 gc_tracer->report_gc_heap_summary(when, heap_summary);
2561
2562 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2563 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2564 }
2565
2566 void G1CollectedHeap::gc_prologue(bool full) {
2567 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2568
2569 // This summary needs to be printed before incrementing total collections.
2570 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2571
2572 // Update common counters.
2573 increment_total_collections(full /* full gc */);
2574 if (full || collector_state()->in_concurrent_start_gc()) {
2575 increment_old_marking_cycles_started();
2576 }
2577
2578 // Fill TLAB's and such
2579 {
2580 Ticks start = Ticks::now();
2581 ensure_parsability(true);
2582 Tickspan dt = Ticks::now() - start;
2583 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2584 }
2585
2586 if (!full) {
2587 // Flush dirty card queues to qset, so later phases don't need to account
2588 // for partially filled per-thread queues and such. Not needed for full
2589 // collections, which ignore those logs.
2590 Ticks start = Ticks::now();
2591 G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2592 Tickspan dt = Ticks::now() - start;
2593 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2594 }
2595 }
2596
2597 void G1CollectedHeap::gc_epilogue(bool full) {
2598 // Update common counters.
2599 if (full) {
2600 // Update the number of full collections that have been completed.
2601 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2602 }
2603
2604 // We are at the end of the GC. Total collections has already been increased.
2605 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2606
2607 #if COMPILER2_OR_JVMCI
2608 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2609 #endif
2610
2611 double start = os::elapsedTime();
2612 resize_all_tlabs();
2613 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2614
2615 MemoryService::track_memory_usage();
2616 // We have just completed a GC. Update the soft reference
2617 // policy with the new heap occupancy
2618 Universe::heap()->update_capacity_and_used_at_gc();
2619
2620 // Print NUMA statistics.
2621 _numa->print_statistics();
2622
2623 _collection_pause_end = Ticks::now();
2624 }
2625
2626 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2627 return _hrm.uncommit_inactive_regions(region_limit);
2628 }
2629
2630 bool G1CollectedHeap::has_uncommittable_regions() {
2631 return _hrm.has_inactive_regions();
2632 }
2633
2634 void G1CollectedHeap::uncommit_regions_if_necessary() {
2635 if (has_uncommittable_regions()) {
2636 G1UncommitRegionTask::enqueue();
2637 }
2638 }
2639
2640 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2641 LogTarget(Trace, gc, heap, verify) lt;
2642
2643 if (lt.is_enabled()) {
2644 LogStream ls(lt);
2645 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2646 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2647 heap_region_iterate(&cl);
2648 }
2649 }
2650
2651 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2652 uint gc_count_before,
2653 bool* succeeded,
2654 GCCause::Cause gc_cause) {
2655 assert_heap_not_locked_and_not_at_safepoint();
2656 VM_G1CollectForAllocation op(word_size,
2657 gc_count_before,
2658 gc_cause,
2659 policy()->max_pause_time_ms());
2660 VMThread::execute(&op);
2661
2662 HeapWord* result = op.result();
2663 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2664 assert(result == NULL || ret_succeeded,
2665 "the result should be NULL if the VM did not succeed");
2666 *succeeded = ret_succeeded;
2667
2668 assert_heap_not_locked();
2669 return result;
2670 }
2671
2672 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2673 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2674
2675 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2676 if (concurrent_operation_is_full_mark) {
2677 _cm->post_concurrent_mark_start();
2678 _cm_thread->start_full_mark();
2679 } else {
2680 _cm->post_concurrent_undo_start();
2681 _cm_thread->start_undo_mark();
2682 }
2683 CGC_lock->notify();
2684 }
2685
2686 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2687 // We don't nominate objects with many remembered set entries, on
2688 // the assumption that such objects are likely still live.
2689 HeapRegionRemSet* rem_set = r->rem_set();
2690
2691 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2692 rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold) :
2693 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2694 }
2695
2696 #ifndef PRODUCT
2697 void G1CollectedHeap::verify_region_attr_remset_update() {
2698 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2699 public:
2700 virtual bool do_heap_region(HeapRegion* r) {
2701 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2702 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2703 assert(r->rem_set()->is_tracked() == needs_remset_update,
2704 "Region %u remset tracking status (%s) different to region attribute (%s)",
2705 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2706 return false;
2707 }
2708 } cl;
2709 heap_region_iterate(&cl);
2710 }
2711 #endif
2712
2713 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2714 public:
2715 bool do_heap_region(HeapRegion* hr) {
2716 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2717 hr->verify_rem_set();
2718 }
2719 return false;
2720 }
2721 };
2722
2723 uint G1CollectedHeap::num_task_queues() const {
2724 return _task_queues->size();
2725 }
2726
2727 #if TASKQUEUE_STATS
2728 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2729 st->print_raw_cr("GC Task Stats");
2730 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2731 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2732 }
2733
2734 void G1CollectedHeap::print_taskqueue_stats() const {
2735 if (!log_is_enabled(Trace, gc, task, stats)) {
2736 return;
2737 }
2738 Log(gc, task, stats) log;
2739 ResourceMark rm;
2740 LogStream ls(log.trace());
2741 outputStream* st = &ls;
2742
2743 print_taskqueue_stats_hdr(st);
2744
2745 TaskQueueStats totals;
2746 const uint n = num_task_queues();
2747 for (uint i = 0; i < n; ++i) {
2748 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2749 totals += task_queue(i)->stats;
2750 }
2751 st->print_raw("tot "); totals.print(st); st->cr();
2752
2753 DEBUG_ONLY(totals.verify());
2754 }
2755
2756 void G1CollectedHeap::reset_taskqueue_stats() {
2757 const uint n = num_task_queues();
2758 for (uint i = 0; i < n; ++i) {
2759 task_queue(i)->stats.reset();
2760 }
2761 }
2762 #endif // TASKQUEUE_STATS
2763
2764 void G1CollectedHeap::wait_for_root_region_scanning() {
2765 double scan_wait_start = os::elapsedTime();
2766 // We have to wait until the CM threads finish scanning the
2767 // root regions as it's the only way to ensure that all the
2768 // objects on them have been correctly scanned before we start
2769 // moving them during the GC.
2770 bool waited = _cm->root_regions()->wait_until_scan_finished();
2771 double wait_time_ms = 0.0;
2772 if (waited) {
2773 double scan_wait_end = os::elapsedTime();
2774 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2775 }
2776 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2777 }
2778
2779 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2780 private:
2781 G1HRPrinter* _hr_printer;
2782 public:
2783 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2784
2785 virtual bool do_heap_region(HeapRegion* r) {
2786 _hr_printer->cset(r);
2787 return false;
2788 }
2789 };
2790
2791 void G1CollectedHeap::start_new_collection_set() {
2792 double start = os::elapsedTime();
2793
2794 collection_set()->start_incremental_building();
2795
2796 clear_region_attr();
2797
2798 guarantee(_eden.length() == 0, "eden should have been cleared");
2799 policy()->transfer_survivors_to_cset(survivor());
2800
2801 // We redo the verification but now wrt to the new CSet which
2802 // has just got initialized after the previous CSet was freed.
2803 _cm->verify_no_collection_set_oops();
2804
2805 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2806 }
2807
2808 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2809
2810 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2811 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2812 collection_set()->optional_region_length());
2813
2814 _cm->verify_no_collection_set_oops();
2815
2816 if (_hr_printer.is_active()) {
2817 G1PrintCollectionSetClosure cl(&_hr_printer);
2818 _collection_set.iterate(&cl);
2819 _collection_set.iterate_optional(&cl);
2820 }
2821 }
2822
2823 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2824 if (collector_state()->in_concurrent_start_gc()) {
2825 return G1HeapVerifier::G1VerifyConcurrentStart;
2826 } else if (collector_state()->in_young_only_phase()) {
2827 return G1HeapVerifier::G1VerifyYoungNormal;
2828 } else {
2829 return G1HeapVerifier::G1VerifyMixed;
2830 }
2831 }
2832
2833 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2834 if (VerifyRememberedSets) {
2835 log_info(gc, verify)("[Verifying RemSets before GC]");
2836 VerifyRegionRemSetClosure v_cl;
2837 heap_region_iterate(&v_cl);
2838 }
2839 _verifier->verify_before_gc(type);
2840 _verifier->check_bitmaps("GC Start");
2841 verify_numa_regions("GC Start");
2842 }
2843
2844 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2845 if (VerifyRememberedSets) {
2846 log_info(gc, verify)("[Verifying RemSets after GC]");
2847 VerifyRegionRemSetClosure v_cl;
2848 heap_region_iterate(&v_cl);
2849 }
2850 _verifier->verify_after_gc(type);
2851 _verifier->check_bitmaps("GC End");
2852 verify_numa_regions("GC End");
2853 }
2854
2855 void G1CollectedHeap::expand_heap_after_young_collection(){
2856 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2857 if (expand_bytes > 0) {
2858 // No need for an ergo logging here,
2859 // expansion_amount() does this when it returns a value > 0.
2860 double expand_ms = 0.0;
2861 if (!expand(expand_bytes, _workers, &expand_ms)) {
2862 // We failed to expand the heap. Cannot do anything about it.
2863 }
2864 phase_times()->record_expand_heap_time(expand_ms);
2865 }
2866 }
2867
2868 void G1CollectedHeap::set_young_gc_name(char* young_gc_name) {
2869 G1GCPauseType pause_type =
2870 // The strings for all Concurrent Start pauses are the same, so the parameter
2871 // does not matter here.
2872 collector_state()->young_gc_pause_type(false /* concurrent_operation_is_full_mark */);
2873 snprintf(young_gc_name,
2874 MaxYoungGCNameLength,
2875 "Pause Young (%s)",
2876 G1GCPauseTypeHelper::to_string(pause_type));
2877 }
2878
2879 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2880 assert_at_safepoint_on_vm_thread();
2881 guarantee(!is_gc_active(), "collection is not reentrant");
2882
2883 if (GCLocker::check_active_before_gc()) {
2884 return false;
2885 }
2886
2887 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2888 return true;
2889 }
2890
2891 void G1CollectedHeap::gc_tracer_report_gc_start() {
2892 _gc_timer_stw->register_gc_start();
2893 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2894 }
2895
2896 void G1CollectedHeap::gc_tracer_report_gc_end(bool concurrent_operation_is_full_mark,
2897 G1EvacuationInfo& evacuation_info) {
2898 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
2899 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
2900
2901 _gc_timer_stw->register_gc_end();
2902 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(),
2903 _gc_timer_stw->time_partitions());
2904 }
2905
2906 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2907 GCIdMark gc_id_mark;
2908
2909 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2910 ResourceMark rm;
2911
2912 policy()->note_gc_start();
2913
2914 gc_tracer_report_gc_start();
2915
2916 wait_for_root_region_scanning();
2917
2918 print_heap_before_gc();
2919 print_heap_regions();
2920 trace_heap_before_gc(_gc_tracer_stw);
2921
2922 _verifier->verify_region_sets_optional();
2923 _verifier->verify_dirty_young_regions();
2924
2925 // We should not be doing concurrent start unless the concurrent mark thread is running
2926 if (!_cm_thread->should_terminate()) {
2927 // This call will decide whether this pause is a concurrent start
2928 // pause. If it is, in_concurrent_start_gc() will return true
2929 // for the duration of this pause.
2930 policy()->decide_on_conc_mark_initiation();
2931 }
2932
2933 // We do not allow concurrent start to be piggy-backed on a mixed GC.
2934 assert(!collector_state()->in_concurrent_start_gc() ||
2935 collector_state()->in_young_only_phase(), "sanity");
2936 // We also do not allow mixed GCs during marking.
2937 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2938
2939 // Record whether this pause may need to trigger a concurrent operation. Later,
2940 // when we signal the G1ConcurrentMarkThread, the collector state has already
2941 // been reset for the next pause.
2942 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2943 bool concurrent_operation_is_full_mark = false;
2944
2945 // Inner scope for scope based logging, timers, and stats collection
2946 {
2947 G1EvacuationInfo evacuation_info;
2948
2949 GCTraceCPUTime tcpu;
2950
2951 char young_gc_name[MaxYoungGCNameLength];
2952 set_young_gc_name(young_gc_name);
2953
2954 GCTraceTime(Info, gc) tm(young_gc_name, NULL, gc_cause(), true);
2955
2956 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2957 workers()->active_workers(),
2958 Threads::number_of_non_daemon_threads());
2959 active_workers = workers()->update_active_workers(active_workers);
2960 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2961
2962 G1MonitoringScope ms(g1mm(),
2963 false /* full_gc */,
2964 collector_state()->in_mixed_phase() /* all_memory_pools_affected */);
2965
2966 G1HeapTransition heap_transition(this);
2967
2968 {
2969 IsGCActiveMark x;
2970
2971 gc_prologue(false);
2972
2973 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
2974 verify_before_young_collection(verify_type);
2975
2976 {
2977 // The elapsed time induced by the start time below deliberately elides
2978 // the possible verification above.
2979 double sample_start_time_sec = os::elapsedTime();
2980
2981 // Please see comment in g1CollectedHeap.hpp and
2982 // G1CollectedHeap::ref_processing_init() to see how
2983 // reference processing currently works in G1.
2984 _ref_processor_stw->enable_discovery();
2985
2986 // We want to temporarily turn off discovery by the
2987 // CM ref processor, if necessary, and turn it back on
2988 // on again later if we do. Using a scoped
2989 // NoRefDiscovery object will do this.
2990 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2991
2992 policy()->record_collection_pause_start(sample_start_time_sec);
2993
2994 // Forget the current allocation region (we might even choose it to be part
2995 // of the collection set!).
2996 _allocator->release_mutator_alloc_regions();
2997
2998 calculate_collection_set(evacuation_info, target_pause_time_ms);
2999
3000 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3001 G1ParScanThreadStateSet per_thread_states(this,
3002 &rdcqs,
3003 workers()->active_workers(),
3004 collection_set()->young_region_length(),
3005 collection_set()->optional_region_length());
3006 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3007
3008 bool may_do_optional_evacuation = _collection_set.optional_region_length() != 0;
3009 // Actually do the work...
3010 evacuate_initial_collection_set(&per_thread_states, may_do_optional_evacuation);
3011
3012 if (may_do_optional_evacuation) {
3013 evacuate_optional_collection_set(&per_thread_states);
3014 }
3015 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3016
3017 start_new_collection_set();
3018
3019 _survivor_evac_stats.adjust_desired_plab_sz();
3020 _old_evac_stats.adjust_desired_plab_sz();
3021
3022 allocate_dummy_regions();
3023
3024 _allocator->init_mutator_alloc_regions();
3025
3026 expand_heap_after_young_collection();
3027
3028 // Refine the type of a concurrent mark operation now that we did the
3029 // evacuation, eventually aborting it.
3030 concurrent_operation_is_full_mark = policy()->concurrent_operation_is_full_mark("Revise IHOP");
3031
3032 // Need to report the collection pause now since record_collection_pause_end()
3033 // modifies it to the next state.
3034 _gc_tracer_stw->report_young_gc_pause(collector_state()->young_gc_pause_type(concurrent_operation_is_full_mark));
3035
3036 double sample_end_time_sec = os::elapsedTime();
3037 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3038 policy()->record_collection_pause_end(pause_time_ms, concurrent_operation_is_full_mark);
3039 }
3040
3041 verify_after_young_collection(verify_type);
3042
3043 gc_epilogue(false);
3044 }
3045
3046 // Print the remainder of the GC log output.
3047 if (evacuation_failed()) {
3048 log_info(gc)("To-space exhausted");
3049 }
3050
3051 policy()->print_phases();
3052 heap_transition.print();
3053
3054 _hrm.verify_optional();
3055 _verifier->verify_region_sets_optional();
3056
3057 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3058 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3059
3060 print_heap_after_gc();
3061 print_heap_regions();
3062 trace_heap_after_gc(_gc_tracer_stw);
3063
3064 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3065 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3066 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3067 // before any GC notifications are raised.
3068 g1mm()->update_sizes();
3069
3070 gc_tracer_report_gc_end(concurrent_operation_is_full_mark, evacuation_info);
3071 }
3072 // It should now be safe to tell the concurrent mark thread to start
3073 // without its logging output interfering with the logging output
3074 // that came from the pause.
3075
3076 if (should_start_concurrent_mark_operation) {
3077 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
3078 // thread(s) could be running concurrently with us. Make sure that anything
3079 // after this point does not assume that we are the only GC thread running.
3080 // Note: of course, the actual marking work will not start until the safepoint
3081 // itself is released in SuspendibleThreadSet::desynchronize().
3082 start_concurrent_cycle(concurrent_operation_is_full_mark);
3083 ConcurrentGCBreakpoints::notify_idle_to_active();
3084 }
3085 }
3086
3087 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3088 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3089 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3090 }
3091
3092 bool G1ParEvacuateFollowersClosure::offer_termination() {
3093 EventGCPhaseParallel event;
3094 G1ParScanThreadState* const pss = par_scan_state();
3095 start_term_time();
3096 const bool res = (terminator() == nullptr) ? true : terminator()->offer_termination();
3097 end_term_time();
3098 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3099 return res;
3100 }
3101
3102 void G1ParEvacuateFollowersClosure::do_void() {
3103 EventGCPhaseParallel event;
3104 G1ParScanThreadState* const pss = par_scan_state();
3105 pss->trim_queue();
3106 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3107 do {
3108 EventGCPhaseParallel event;
3109 pss->steal_and_trim_queue(queues());
3110 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3111 } while (!offer_termination());
3112 }
3113
3114 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3115 bool class_unloading_occurred) {
3116 uint num_workers = workers()->active_workers();
3117 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred);
3118 workers()->run_task(&unlink_task);
3119 }
3120
3121 // Weak Reference Processing support
3122
3123 bool G1STWIsAliveClosure::do_object_b(oop p) {
3124 // An object is reachable if it is outside the collection set,
3125 // or is inside and copied.
3126 return !_g1h->is_in_cset(p) || p->is_forwarded();
3127 }
3128
3129 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3130 assert(obj != NULL, "must not be NULL");
3131 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3132 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3133 // may falsely indicate that this is not the case here: however the collection set only
3134 // contains old regions when concurrent mark is not running.
3135 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3136 }
3137
3138 // Non Copying Keep Alive closure
3139 class G1KeepAliveClosure: public OopClosure {
3140 G1CollectedHeap*_g1h;
3141 public:
3142 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3143 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3144 void do_oop(oop* p) {
3145 oop obj = *p;
3146 assert(obj != NULL, "the caller should have filtered out NULL values");
3147
3148 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3149 if (!region_attr.is_in_cset_or_humongous()) {
3150 return;
3151 }
3152 if (region_attr.is_in_cset()) {
3153 assert( obj->is_forwarded(), "invariant" );
3154 *p = obj->forwardee();
3155 } else {
3156 assert(!obj->is_forwarded(), "invariant" );
3157 assert(region_attr.is_humongous(),
3158 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3159 _g1h->set_humongous_is_live(obj);
3160 }
3161 }
3162 };
3163
3164 // Copying Keep Alive closure - can be called from both
3165 // serial and parallel code as long as different worker
3166 // threads utilize different G1ParScanThreadState instances
3167 // and different queues.
3168
3169 class G1CopyingKeepAliveClosure: public OopClosure {
3170 G1CollectedHeap* _g1h;
3171 G1ParScanThreadState* _par_scan_state;
3172
3173 public:
3174 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3175 G1ParScanThreadState* pss):
3176 _g1h(g1h),
3177 _par_scan_state(pss)
3178 {}
3179
3180 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3181 virtual void do_oop( oop* p) { do_oop_work(p); }
3182
3183 template <class T> void do_oop_work(T* p) {
3184 oop obj = RawAccess<>::oop_load(p);
3185
3186 if (_g1h->is_in_cset_or_humongous(obj)) {
3187 // If the referent object has been forwarded (either copied
3188 // to a new location or to itself in the event of an
3189 // evacuation failure) then we need to update the reference
3190 // field and, if both reference and referent are in the G1
3191 // heap, update the RSet for the referent.
3192 //
3193 // If the referent has not been forwarded then we have to keep
3194 // it alive by policy. Therefore we have copy the referent.
3195 //
3196 // When the queue is drained (after each phase of reference processing)
3197 // the object and it's followers will be copied, the reference field set
3198 // to point to the new location, and the RSet updated.
3199 _par_scan_state->push_on_queue(ScannerTask(p));
3200 }
3201 }
3202 };
3203
3204 // Special closure for enqueuing discovered fields: during enqueue the card table
3205 // may not be in shape to properly handle normal barrier calls (e.g. card marks
3206 // in regions that failed evacuation, scribbling of various values by card table
3207 // scan code). Additionally the regular barrier enqueues into the "global"
3208 // DCQS, but during GC we need these to-be-refined entries in the GC local queue
3209 // so that after clearing the card table, the redirty cards phase will properly
3210 // mark all dirty cards to be picked up by refinement.
3211 class G1EnqueueDiscoveredFieldClosure : public EnqueueDiscoveredFieldClosure {
3212 G1CollectedHeap* _g1h;
3213 G1ParScanThreadState* _pss;
3214
3215 public:
3216 G1EnqueueDiscoveredFieldClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : _g1h(g1h), _pss(pss) { }
3217
3218 virtual void enqueue(HeapWord* discovered_field_addr, oop value) {
3219 assert(_g1h->is_in(discovered_field_addr), PTR_FORMAT " is not in heap ", p2i(discovered_field_addr));
3220 // Store the value first, whatever it is.
3221 RawAccess<>::oop_store(discovered_field_addr, value);
3222 if (value == NULL) {
3223 return;
3224 }
3225 _pss->write_ref_field_post(discovered_field_addr, value);
3226 }
3227 };
3228
3229 // Serial drain queue closure. Called as the 'complete_gc'
3230 // closure for each discovered list in some of the
3231 // reference processing phases.
3232
3233 class G1STWDrainQueueClosure: public VoidClosure {
3234 protected:
3235 G1CollectedHeap* _g1h;
3236 G1ParScanThreadState* _par_scan_state;
3237
3238 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3239
3240 public:
3241 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3242 _g1h(g1h),
3243 _par_scan_state(pss)
3244 { }
3245
3246 void do_void() {
3247 G1ParScanThreadState* const pss = par_scan_state();
3248 pss->trim_queue();
3249 }
3250 };
3251
3252 class G1STWRefProcProxyTask : public RefProcProxyTask {
3253 G1CollectedHeap& _g1h;
3254 G1ParScanThreadStateSet& _pss;
3255 TaskTerminator _terminator;
3256 G1ScannerTasksQueueSet& _task_queues;
3257
3258 public:
3259 G1STWRefProcProxyTask(uint max_workers, G1CollectedHeap& g1h, G1ParScanThreadStateSet& pss, G1ScannerTasksQueueSet& task_queues)
3260 : RefProcProxyTask("G1STWRefProcProxyTask", max_workers),
3261 _g1h(g1h),
3262 _pss(pss),
3263 _terminator(max_workers, &task_queues),
3264 _task_queues(task_queues) {}
3265
3266 void work(uint worker_id) override {
3267 assert(worker_id < _max_workers, "sanity");
3268 uint index = (_tm == RefProcThreadModel::Single) ? 0 : worker_id;
3269 _pss.state_for_worker(index)->set_ref_discoverer(nullptr);
3270 G1STWIsAliveClosure is_alive(&_g1h);
3271 G1CopyingKeepAliveClosure keep_alive(&_g1h, _pss.state_for_worker(index));
3272 G1ParEvacuateFollowersClosure complete_gc(&_g1h, _pss.state_for_worker(index), &_task_queues, _tm == RefProcThreadModel::Single ? nullptr : &_terminator, G1GCPhaseTimes::ObjCopy);
3273 G1EnqueueDiscoveredFieldClosure enqueue(&_g1h, _pss.state_for_worker(index));
3274 _rp_task->rp_work(worker_id, &is_alive, &keep_alive, &enqueue, &complete_gc);
3275 }
3276
3277 void prepare_run_task_hook() override {
3278 _terminator.reset_for_reuse(_queue_count);
3279 }
3280 };
3281
3282 // End of weak reference support closures
3283
3284 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3285 double ref_proc_start = os::elapsedTime();
3286
3287 ReferenceProcessor* rp = _ref_processor_stw;
3288 assert(rp->discovery_enabled(), "should have been enabled");
3289
3290 // Use only a single queue for this PSS.
3291 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3292 pss->set_ref_discoverer(NULL);
3293 assert(pss->queue_is_empty(), "pre-condition");
3294
3295 // Setup the soft refs policy...
3296 rp->setup_policy(false);
3297
3298 ReferenceProcessorPhaseTimes& pt = *phase_times()->ref_phase_times();
3299
3300 ReferenceProcessorStats stats;
3301 uint no_of_gc_workers = workers()->active_workers();
3302
3303 // Parallel reference processing
3304 assert(no_of_gc_workers <= rp->max_num_queues(),
3305 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3306 no_of_gc_workers, rp->max_num_queues());
3307
3308 rp->set_active_mt_degree(no_of_gc_workers);
3309 G1STWRefProcProxyTask task(rp->max_num_queues(), *this, *per_thread_states, *_task_queues);
3310 stats = rp->process_discovered_references(task, pt);
3311
3312 _gc_tracer_stw->report_gc_reference_stats(stats);
3313
3314 // We have completed copying any necessary live referent objects.
3315 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3316
3317 make_pending_list_reachable();
3318
3319 assert(!rp->discovery_enabled(), "Postcondition");
3320 rp->verify_no_references_recorded();
3321
3322 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3323 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3324 }
3325
3326 void G1CollectedHeap::make_pending_list_reachable() {
3327 if (collector_state()->in_concurrent_start_gc()) {
3328 oop pll_head = Universe::reference_pending_list();
3329 if (pll_head != NULL) {
3330 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3331 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3332 }
3333 }
3334 }
3335
3336 static bool do_humongous_object_logging() {
3337 return log_is_enabled(Debug, gc, humongous);
3338 }
3339
3340 bool G1CollectedHeap::should_do_eager_reclaim() const {
3341 // As eager reclaim logging also gives information about humongous objects in
3342 // the heap in general, always do the eager reclaim pass even without known
3343 // candidates.
3344 return (G1EagerReclaimHumongousObjects &&
3345 (has_humongous_reclaim_candidates() || do_humongous_object_logging()));
3346 }
3347
3348 class G1PrepareEvacuationTask : public AbstractGangTask {
3349 class G1PrepareRegionsClosure : public HeapRegionClosure {
3350 G1CollectedHeap* _g1h;
3351 G1PrepareEvacuationTask* _parent_task;
3352 uint _worker_humongous_total;
3353 uint _worker_humongous_candidates;
3354
3355 bool humongous_region_is_candidate(HeapRegion* region) const {
3356 assert(region->is_starts_humongous(), "Must start a humongous object");
3357
3358 oop obj = cast_to_oop(region->bottom());
3359
3360 // Dead objects cannot be eager reclaim candidates. Due to class
3361 // unloading it is unsafe to query their classes so we return early.
3362 if (_g1h->is_obj_dead(obj, region)) {
3363 return false;
3364 }
3365
3366 // If we do not have a complete remembered set for the region, then we can
3367 // not be sure that we have all references to it.
3368 if (!region->rem_set()->is_complete()) {
3369 return false;
3370 }
3371 // Candidate selection must satisfy the following constraints
3372 // while concurrent marking is in progress:
3373 //
3374 // * In order to maintain SATB invariants, an object must not be
3375 // reclaimed if it was allocated before the start of marking and
3376 // has not had its references scanned. Such an object must have
3377 // its references (including type metadata) scanned to ensure no
3378 // live objects are missed by the marking process. Objects
3379 // allocated after the start of concurrent marking don't need to
3380 // be scanned.
3381 //
3382 // * An object must not be reclaimed if it is on the concurrent
3383 // mark stack. Objects allocated after the start of concurrent
3384 // marking are never pushed on the mark stack.
3385 //
3386 // Nominating only objects allocated after the start of concurrent
3387 // marking is sufficient to meet both constraints. This may miss
3388 // some objects that satisfy the constraints, but the marking data
3389 // structures don't support efficiently performing the needed
3390 // additional tests or scrubbing of the mark stack.
3391 //
3392 // However, we presently only nominate is_typeArray() objects.
3393 // A humongous object containing references induces remembered
3394 // set entries on other regions. In order to reclaim such an
3395 // object, those remembered sets would need to be cleaned up.
3396 //
3397 // We also treat is_typeArray() objects specially, allowing them
3398 // to be reclaimed even if allocated before the start of
3399 // concurrent mark. For this we rely on mark stack insertion to
3400 // exclude is_typeArray() objects, preventing reclaiming an object
3401 // that is in the mark stack. We also rely on the metadata for
3402 // such objects to be built-in and so ensured to be kept live.
3403 // Frequent allocation and drop of large binary blobs is an
3404 // important use case for eager reclaim, and this special handling
3405 // may reduce needed headroom.
3406
3407 return obj->is_typeArray() &&
3408 _g1h->is_potential_eager_reclaim_candidate(region);
3409 }
3410
3411 public:
3412 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3413 _g1h(g1h),
3414 _parent_task(parent_task),
3415 _worker_humongous_total(0),
3416 _worker_humongous_candidates(0) { }
3417
3418 ~G1PrepareRegionsClosure() {
3419 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3420 _parent_task->add_humongous_total(_worker_humongous_total);
3421 }
3422
3423 virtual bool do_heap_region(HeapRegion* hr) {
3424 // First prepare the region for scanning
3425 _g1h->rem_set()->prepare_region_for_scan(hr);
3426
3427 // Now check if region is a humongous candidate
3428 if (!hr->is_starts_humongous()) {
3429 _g1h->register_region_with_region_attr(hr);
3430 return false;
3431 }
3432
3433 uint index = hr->hrm_index();
3434 if (humongous_region_is_candidate(hr)) {
3435 _g1h->set_humongous_reclaim_candidate(index, true);
3436 _g1h->register_humongous_region_with_region_attr(index);
3437 _worker_humongous_candidates++;
3438 // We will later handle the remembered sets of these regions.
3439 } else {
3440 _g1h->set_humongous_reclaim_candidate(index, false);
3441 _g1h->register_region_with_region_attr(hr);
3442 }
3443 log_debug(gc, humongous)("Humongous region %u (object size " SIZE_FORMAT " @ " PTR_FORMAT ") remset " SIZE_FORMAT " code roots " SIZE_FORMAT " marked %d reclaim candidate %d type array %d",
3444 index,
3445 (size_t)cast_to_oop(hr->bottom())->size() * HeapWordSize,
3446 p2i(hr->bottom()),
3447 hr->rem_set()->occupied(),
3448 hr->rem_set()->strong_code_roots_list_length(),
3449 _g1h->concurrent_mark()->next_mark_bitmap()->is_marked(hr->bottom()),
3450 _g1h->is_humongous_reclaim_candidate(index),
3451 cast_to_oop(hr->bottom())->is_typeArray()
3452 );
3453 _worker_humongous_total++;
3454
3455 return false;
3456 }
3457 };
3458
3459 G1CollectedHeap* _g1h;
3460 HeapRegionClaimer _claimer;
3461 volatile uint _humongous_total;
3462 volatile uint _humongous_candidates;
3463 public:
3464 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3465 AbstractGangTask("Prepare Evacuation"),
3466 _g1h(g1h),
3467 _claimer(_g1h->workers()->active_workers()),
3468 _humongous_total(0),
3469 _humongous_candidates(0) { }
3470
3471 void work(uint worker_id) {
3472 G1PrepareRegionsClosure cl(_g1h, this);
3473 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3474 }
3475
3476 void add_humongous_candidates(uint candidates) {
3477 Atomic::add(&_humongous_candidates, candidates);
3478 }
3479
3480 void add_humongous_total(uint total) {
3481 Atomic::add(&_humongous_total, total);
3482 }
3483
3484 uint humongous_candidates() {
3485 return _humongous_candidates;
3486 }
3487
3488 uint humongous_total() {
3489 return _humongous_total;
3490 }
3491 };
3492
3493 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3494 _bytes_used_during_gc = 0;
3495
3496 _expand_heap_after_alloc_failure = true;
3497 Atomic::store(&_num_regions_failed_evacuation, 0u);
3498
3499 memset((void*)_regions_failed_evacuation, false, sizeof(bool) * max_regions());
3500
3501 // Disable the hot card cache.
3502 _hot_card_cache->reset_hot_cache_claimed_index();
3503 _hot_card_cache->set_use_cache(false);
3504
3505 // Initialize the GC alloc regions.
3506 _allocator->init_gc_alloc_regions(evacuation_info);
3507
3508 {
3509 Ticks start = Ticks::now();
3510 rem_set()->prepare_for_scan_heap_roots();
3511 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3512 }
3513
3514 {
3515 G1PrepareEvacuationTask g1_prep_task(this);
3516 Tickspan task_time = run_task_timed(&g1_prep_task);
3517
3518 phase_times()->record_register_regions(task_time.seconds() * 1000.0);
3519 _num_humongous_objects = g1_prep_task.humongous_total();
3520 _num_humongous_reclaim_candidates = g1_prep_task.humongous_candidates();
3521 }
3522
3523 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3524 _preserved_marks_set.assert_empty();
3525
3526 #if COMPILER2_OR_JVMCI
3527 DerivedPointerTable::clear();
3528 #endif
3529
3530 // Concurrent start needs claim bits to keep track of the marked-through CLDs.
3531 if (collector_state()->in_concurrent_start_gc()) {
3532 concurrent_mark()->pre_concurrent_start(gc_cause());
3533
3534 double start_clear_claimed_marks = os::elapsedTime();
3535
3536 ClassLoaderDataGraph::clear_claimed_marks();
3537
3538 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3539 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3540 }
3541
3542 // Should G1EvacuationFailureALot be in effect for this GC?
3543 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3544 }
3545
3546 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3547 protected:
3548 G1CollectedHeap* _g1h;
3549 G1ParScanThreadStateSet* _per_thread_states;
3550 G1ScannerTasksQueueSet* _task_queues;
3551 TaskTerminator _terminator;
3552 uint _num_workers;
3553
3554 void evacuate_live_objects(G1ParScanThreadState* pss,
3555 uint worker_id,
3556 G1GCPhaseTimes::GCParPhases objcopy_phase,
3557 G1GCPhaseTimes::GCParPhases termination_phase) {
3558 G1GCPhaseTimes* p = _g1h->phase_times();
3559
3560 Ticks start = Ticks::now();
3561 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3562 cl.do_void();
3563
3564 assert(pss->queue_is_empty(), "should be empty");
3565
3566 Tickspan evac_time = (Ticks::now() - start);
3567 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3568
3569 if (termination_phase == G1GCPhaseTimes::Termination) {
3570 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3571 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3572 } else {
3573 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3574 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3575 }
3576 assert(pss->trim_ticks().value() == 0,
3577 "Unexpected partial trimming during evacuation value " JLONG_FORMAT,
3578 pss->trim_ticks().value());
3579 }
3580
3581 virtual void start_work(uint worker_id) { }
3582
3583 virtual void end_work(uint worker_id) { }
3584
3585 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3586
3587 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3588
3589 public:
3590 G1EvacuateRegionsBaseTask(const char* name,
3591 G1ParScanThreadStateSet* per_thread_states,
3592 G1ScannerTasksQueueSet* task_queues,
3593 uint num_workers) :
3594 AbstractGangTask(name),
3595 _g1h(G1CollectedHeap::heap()),
3596 _per_thread_states(per_thread_states),
3597 _task_queues(task_queues),
3598 _terminator(num_workers, _task_queues),
3599 _num_workers(num_workers)
3600 { }
3601
3602 void work(uint worker_id) {
3603 start_work(worker_id);
3604
3605 {
3606 ResourceMark rm;
3607
3608 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3609 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3610
3611 scan_roots(pss, worker_id);
3612 evacuate_live_objects(pss, worker_id);
3613 }
3614
3615 end_work(worker_id);
3616 }
3617 };
3618
3619 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3620 G1RootProcessor* _root_processor;
3621 bool _has_optional_evacuation_work;
3622
3623 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3624 _root_processor->evacuate_roots(pss, worker_id);
3625 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy, _has_optional_evacuation_work);
3626 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3627 }
3628
3629 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3630 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3631 }
3632
3633 void start_work(uint worker_id) {
3634 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3635 }
3636
3637 void end_work(uint worker_id) {
3638 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3639 }
3640
3641 public:
3642 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3643 G1ParScanThreadStateSet* per_thread_states,
3644 G1ScannerTasksQueueSet* task_queues,
3645 G1RootProcessor* root_processor,
3646 uint num_workers,
3647 bool has_optional_evacuation_work) :
3648 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3649 _root_processor(root_processor),
3650 _has_optional_evacuation_work(has_optional_evacuation_work)
3651 { }
3652 };
3653
3654 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states,
3655 bool has_optional_evacuation_work) {
3656 G1GCPhaseTimes* p = phase_times();
3657
3658 {
3659 Ticks start = Ticks::now();
3660 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3661 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3662 }
3663
3664 Tickspan task_time;
3665 const uint num_workers = workers()->active_workers();
3666
3667 Ticks start_processing = Ticks::now();
3668 {
3669 G1RootProcessor root_processor(this, num_workers);
3670 G1EvacuateRegionsTask g1_par_task(this,
3671 per_thread_states,
3672 _task_queues,
3673 &root_processor,
3674 num_workers,
3675 has_optional_evacuation_work);
3676 task_time = run_task_timed(&g1_par_task);
3677 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3678 // To extract its code root fixup time we measure total time of this scope and
3679 // subtract from the time the WorkGang task took.
3680 }
3681 Tickspan total_processing = Ticks::now() - start_processing;
3682
3683 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3684 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3685
3686 rem_set()->complete_evac_phase(has_optional_evacuation_work);
3687 }
3688
3689 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3690
3691 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3692 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy, true /* remember_already_scanned_cards */);
3693 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3694 }
3695
3696 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3697 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3698 }
3699
3700 public:
3701 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3702 G1ScannerTasksQueueSet* queues,
3703 uint num_workers) :
3704 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3705 }
3706 };
3707
3708 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3709 class G1MarkScope : public MarkScope { };
3710
3711 Tickspan task_time;
3712
3713 Ticks start_processing = Ticks::now();
3714 {
3715 G1MarkScope code_mark_scope;
3716 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3717 task_time = run_task_timed(&task);
3718 // See comment in evacuate_collection_set() for the reason of the scope.
3719 }
3720 Tickspan total_processing = Ticks::now() - start_processing;
3721
3722 G1GCPhaseTimes* p = phase_times();
3723 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3724 }
3725
3726 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3727 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3728
3729 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3730
3731 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3732 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3733
3734 if (time_left_ms < 0 ||
3735 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3736 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3737 _collection_set.optional_region_length(), time_left_ms);
3738 break;
3739 }
3740
3741 {
3742 Ticks start = Ticks::now();
3743 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3744 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3745 }
3746
3747 {
3748 Ticks start = Ticks::now();
3749 evacuate_next_optional_regions(per_thread_states);
3750 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3751 }
3752
3753 rem_set()->complete_evac_phase(true /* has_more_than_one_evacuation_phase */);
3754 }
3755
3756 _collection_set.abandon_optional_collection_set(per_thread_states);
3757 }
3758
3759 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3760 G1RedirtyCardsQueueSet* rdcqs,
3761 G1ParScanThreadStateSet* per_thread_states) {
3762 G1GCPhaseTimes* p = phase_times();
3763
3764 // Process any discovered reference objects - we have
3765 // to do this _before_ we retire the GC alloc regions
3766 // as we may have to copy some 'reachable' referent
3767 // objects (and their reachable sub-graphs) that were
3768 // not copied during the pause.
3769 process_discovered_references(per_thread_states);
3770
3771 G1STWIsAliveClosure is_alive(this);
3772 G1KeepAliveClosure keep_alive(this);
3773
3774 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
3775
3776 _allocator->release_gc_alloc_regions(evacuation_info);
3777
3778 post_evacuate_cleanup_1(per_thread_states, rdcqs);
3779
3780 post_evacuate_cleanup_2(&_preserved_marks_set, rdcqs, &evacuation_info, per_thread_states->surviving_young_words());
3781
3782 assert_used_and_recalculate_used_equal(this);
3783
3784 rebuild_free_region_list();
3785
3786 record_obj_copy_mem_stats();
3787
3788 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3789 evacuation_info.set_bytes_used(_bytes_used_during_gc);
3790
3791 policy()->print_age_table();
3792 }
3793
3794 void G1CollectedHeap::record_obj_copy_mem_stats() {
3795 policy()->old_gen_alloc_tracker()->
3796 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3797
3798 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3799 create_g1_evac_summary(&_old_evac_stats));
3800 }
3801
3802 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
3803 assert(!hr->is_free(), "the region should not be free");
3804 assert(!hr->is_empty(), "the region should not be empty");
3805 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3806
3807 if (G1VerifyBitmaps) {
3808 MemRegion mr(hr->bottom(), hr->end());
3809 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3810 }
3811
3812 // Clear the card counts for this region.
3813 // Note: we only need to do this if the region is not young
3814 // (since we don't refine cards in young regions).
3815 if (!hr->is_young()) {
3816 _hot_card_cache->reset_card_counts(hr);
3817 }
3818
3819 // Reset region metadata to allow reuse.
3820 hr->hr_clear(true /* clear_space */);
3821 _policy->remset_tracker()->update_at_free(hr);
3822
3823 if (free_list != NULL) {
3824 free_list->add_ordered(hr);
3825 }
3826 }
3827
3828 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3829 FreeRegionList* free_list) {
3830 assert(hr->is_humongous(), "this is only for humongous regions");
3831 hr->clear_humongous();
3832 free_region(hr, free_list);
3833 }
3834
3835 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
3836 const uint archive_regions_removed,
3837 const uint humongous_regions_removed) {
3838 if (old_regions_removed > 0 || archive_regions_removed > 0 || humongous_regions_removed > 0) {
3839 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3840 _old_set.bulk_remove(old_regions_removed);
3841 _archive_set.bulk_remove(archive_regions_removed);
3842 _humongous_set.bulk_remove(humongous_regions_removed);
3843 }
3844
3845 }
3846
3847 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3848 assert(list != NULL, "list can't be null");
3849 if (!list->is_empty()) {
3850 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3851 _hrm.insert_list_into_free_list(list);
3852 }
3853 }
3854
3855 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3856 decrease_used(bytes);
3857 }
3858
3859 void G1CollectedHeap::post_evacuate_cleanup_1(G1ParScanThreadStateSet* per_thread_states,
3860 G1RedirtyCardsQueueSet* rdcqs) {
3861 Ticks start = Ticks::now();
3862 {
3863 G1PostEvacuateCollectionSetCleanupTask1 cl(per_thread_states, rdcqs);
3864 run_batch_task(&cl);
3865 }
3866 phase_times()->record_post_evacuate_cleanup_task_1_time((Ticks::now() - start).seconds() * 1000.0);
3867 }
3868
3869 void G1CollectedHeap::post_evacuate_cleanup_2(PreservedMarksSet* preserved_marks,
3870 G1RedirtyCardsQueueSet* rdcqs,
3871 G1EvacuationInfo* evacuation_info,
3872 const size_t* surviving_young_words) {
3873 Ticks start = Ticks::now();
3874 {
3875 G1PostEvacuateCollectionSetCleanupTask2 cl(preserved_marks, rdcqs, evacuation_info, surviving_young_words);
3876 run_batch_task(&cl);
3877 }
3878 phase_times()->record_post_evacuate_cleanup_task_2_time((Ticks::now() - start).seconds() * 1000.0);
3879 }
3880
3881 void G1CollectedHeap::clear_eden() {
3882 _eden.clear();
3883 }
3884
3885 void G1CollectedHeap::clear_collection_set() {
3886 collection_set()->clear();
3887 }
3888
3889 void G1CollectedHeap::rebuild_free_region_list() {
3890 Ticks start = Ticks::now();
3891 _hrm.rebuild_free_list(workers());
3892 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
3893 }
3894
3895 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
3896 public:
3897 virtual bool do_heap_region(HeapRegion* r) {
3898 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
3899 G1CollectedHeap::heap()->clear_region_attr(r);
3900 r->clear_young_index_in_cset();
3901 return false;
3902 }
3903 };
3904
3905 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
3906 G1AbandonCollectionSetClosure cl;
3907 collection_set_iterate_all(&cl);
3908
3909 collection_set->clear();
3910 collection_set->stop_incremental_building();
3911 }
3912
3913 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
3914 return _allocator->is_retained_old_region(hr);
3915 }
3916
3917 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
3918 _eden.add(hr);
3919 _policy->set_region_eden(hr);
3920 }
3921
3922 #ifdef ASSERT
3923
3924 class NoYoungRegionsClosure: public HeapRegionClosure {
3925 private:
3926 bool _success;
3927 public:
3928 NoYoungRegionsClosure() : _success(true) { }
3929 bool do_heap_region(HeapRegion* r) {
3930 if (r->is_young()) {
3931 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
3932 p2i(r->bottom()), p2i(r->end()));
3933 _success = false;
3934 }
3935 return false;
3936 }
3937 bool success() { return _success; }
3938 };
3939
3940 bool G1CollectedHeap::check_young_list_empty() {
3941 bool ret = (young_regions_count() == 0);
3942
3943 NoYoungRegionsClosure closure;
3944 heap_region_iterate(&closure);
3945 ret = ret && closure.success();
3946
3947 return ret;
3948 }
3949
3950 #endif // ASSERT
3951
3952 // Remove the given HeapRegion from the appropriate region set.
3953 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
3954 if (hr->is_archive()) {
3955 _archive_set.remove(hr);
3956 } else if (hr->is_humongous()) {
3957 _humongous_set.remove(hr);
3958 } else if (hr->is_old()) {
3959 _old_set.remove(hr);
3960 } else if (hr->is_young()) {
3961 // Note that emptying the eden and survivor lists is postponed and instead
3962 // done as the first step when rebuilding the regions sets again. The reason
3963 // for this is that during a full GC string deduplication needs to know if
3964 // a collected region was young or old when the full GC was initiated.
3965 hr->uninstall_surv_rate_group();
3966 } else {
3967 // We ignore free regions, we'll empty the free list afterwards.
3968 assert(hr->is_free(), "it cannot be another type");
3969 }
3970 }
3971
3972 void G1CollectedHeap::increase_used(size_t bytes) {
3973 _summary_bytes_used += bytes;
3974 }
3975
3976 void G1CollectedHeap::decrease_used(size_t bytes) {
3977 assert(_summary_bytes_used >= bytes,
3978 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
3979 _summary_bytes_used, bytes);
3980 _summary_bytes_used -= bytes;
3981 }
3982
3983 void G1CollectedHeap::set_used(size_t bytes) {
3984 _summary_bytes_used = bytes;
3985 }
3986
3987 class RebuildRegionSetsClosure : public HeapRegionClosure {
3988 private:
3989 bool _free_list_only;
3990
3991 HeapRegionSet* _old_set;
3992 HeapRegionSet* _archive_set;
3993 HeapRegionSet* _humongous_set;
3994
3995 HeapRegionManager* _hrm;
3996
3997 size_t _total_used;
3998
3999 public:
4000 RebuildRegionSetsClosure(bool free_list_only,
4001 HeapRegionSet* old_set,
4002 HeapRegionSet* archive_set,
4003 HeapRegionSet* humongous_set,
4004 HeapRegionManager* hrm) :
4005 _free_list_only(free_list_only), _old_set(old_set), _archive_set(archive_set),
4006 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
4007 assert(_hrm->num_free_regions() == 0, "pre-condition");
4008 if (!free_list_only) {
4009 assert(_old_set->is_empty(), "pre-condition");
4010 assert(_archive_set->is_empty(), "pre-condition");
4011 assert(_humongous_set->is_empty(), "pre-condition");
4012 }
4013 }
4014
4015 bool do_heap_region(HeapRegion* r) {
4016 if (r->is_empty()) {
4017 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4018 // Add free regions to the free list
4019 r->set_free();
4020 _hrm->insert_into_free_list(r);
4021 } else if (!_free_list_only) {
4022 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4023
4024 if (r->is_humongous()) {
4025 _humongous_set->add(r);
4026 } else if (r->is_archive()) {
4027 _archive_set->add(r);
4028 } else {
4029 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4030 // We now move all (non-humongous, non-old, non-archive) regions to old gen,
4031 // and register them as such.
4032 r->move_to_old();
4033 _old_set->add(r);
4034 }
4035 _total_used += r->used();
4036 }
4037
4038 return false;
4039 }
4040
4041 size_t total_used() {
4042 return _total_used;
4043 }
4044 };
4045
4046 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4047 assert_at_safepoint_on_vm_thread();
4048
4049 if (!free_list_only) {
4050 _eden.clear();
4051 _survivor.clear();
4052 }
4053
4054 RebuildRegionSetsClosure cl(free_list_only,
4055 &_old_set, &_archive_set, &_humongous_set,
4056 &_hrm);
4057 heap_region_iterate(&cl);
4058
4059 if (!free_list_only) {
4060 set_used(cl.total_used());
4061 if (_archive_allocator != NULL) {
4062 _archive_allocator->clear_used();
4063 }
4064 }
4065 assert_used_and_recalculate_used_equal(this);
4066 }
4067
4068 // Methods for the mutator alloc region
4069
4070 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4071 bool force,
4072 uint node_index) {
4073 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4074 bool should_allocate = policy()->should_allocate_mutator_region();
4075 if (force || should_allocate) {
4076 HeapRegion* new_alloc_region = new_region(word_size,
4077 HeapRegionType::Eden,
4078 false /* do_expand */,
4079 node_index);
4080 if (new_alloc_region != NULL) {
4081 set_region_short_lived_locked(new_alloc_region);
4082 _hr_printer.alloc(new_alloc_region, !should_allocate);
4083 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4084 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4085 return new_alloc_region;
4086 }
4087 }
4088 return NULL;
4089 }
4090
4091 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4092 size_t allocated_bytes) {
4093 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4094 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4095
4096 collection_set()->add_eden_region(alloc_region);
4097 increase_used(allocated_bytes);
4098 _eden.add_used_bytes(allocated_bytes);
4099 _hr_printer.retire(alloc_region);
4100
4101 // We update the eden sizes here, when the region is retired,
4102 // instead of when it's allocated, since this is the point that its
4103 // used space has been recorded in _summary_bytes_used.
4104 g1mm()->update_eden_size();
4105 }
4106
4107 // Methods for the GC alloc regions
4108
4109 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4110 if (dest.is_old()) {
4111 return true;
4112 } else {
4113 return survivor_regions_count() < policy()->max_survivor_regions();
4114 }
4115 }
4116
4117 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4118 assert(FreeList_lock->owned_by_self(), "pre-condition");
4119
4120 if (!has_more_regions(dest)) {
4121 return NULL;
4122 }
4123
4124 HeapRegionType type;
4125 if (dest.is_young()) {
4126 type = HeapRegionType::Survivor;
4127 } else {
4128 type = HeapRegionType::Old;
4129 }
4130
4131 HeapRegion* new_alloc_region = new_region(word_size,
4132 type,
4133 true /* do_expand */,
4134 node_index);
4135
4136 if (new_alloc_region != NULL) {
4137 if (type.is_survivor()) {
4138 new_alloc_region->set_survivor();
4139 _survivor.add(new_alloc_region);
4140 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4141 } else {
4142 new_alloc_region->set_old();
4143 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4144 }
4145 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4146 register_region_with_region_attr(new_alloc_region);
4147 _hr_printer.alloc(new_alloc_region);
4148 return new_alloc_region;
4149 }
4150 return NULL;
4151 }
4152
4153 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4154 size_t allocated_bytes,
4155 G1HeapRegionAttr dest) {
4156 _bytes_used_during_gc += allocated_bytes;
4157 if (dest.is_old()) {
4158 old_set_add(alloc_region);
4159 } else {
4160 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4161 _survivor.add_used_bytes(allocated_bytes);
4162 }
4163
4164 bool const during_im = collector_state()->in_concurrent_start_gc();
4165 if (during_im && allocated_bytes > 0) {
4166 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4167 }
4168 _hr_printer.retire(alloc_region);
4169 }
4170
4171 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4172 bool expanded = false;
4173 uint index = _hrm.find_highest_free(&expanded);
4174
4175 if (index != G1_NO_HRM_INDEX) {
4176 if (expanded) {
4177 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4178 HeapRegion::GrainWords * HeapWordSize);
4179 }
4180 return _hrm.allocate_free_regions_starting_at(index, 1);
4181 }
4182 return NULL;
4183 }
4184
4185 // Optimized nmethod scanning
4186
4187 class RegisterNMethodOopClosure: public OopClosure {
4188 G1CollectedHeap* _g1h;
4189 nmethod* _nm;
4190
4191 template <class T> void do_oop_work(T* p) {
4192 T heap_oop = RawAccess<>::oop_load(p);
4193 if (!CompressedOops::is_null(heap_oop)) {
4194 oop obj = CompressedOops::decode_not_null(heap_oop);
4195 HeapRegion* hr = _g1h->heap_region_containing(obj);
4196 assert(!hr->is_continues_humongous(),
4197 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4198 " starting at " HR_FORMAT,
4199 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4200
4201 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4202 hr->add_strong_code_root_locked(_nm);
4203 }
4204 }
4205
4206 public:
4207 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4208 _g1h(g1h), _nm(nm) {}
4209
4210 void do_oop(oop* p) { do_oop_work(p); }
4211 void do_oop(narrowOop* p) { do_oop_work(p); }
4212 };
4213
4214 class UnregisterNMethodOopClosure: public OopClosure {
4215 G1CollectedHeap* _g1h;
4216 nmethod* _nm;
4217
4218 template <class T> void do_oop_work(T* p) {
4219 T heap_oop = RawAccess<>::oop_load(p);
4220 if (!CompressedOops::is_null(heap_oop)) {
4221 oop obj = CompressedOops::decode_not_null(heap_oop);
4222 HeapRegion* hr = _g1h->heap_region_containing(obj);
4223 assert(!hr->is_continues_humongous(),
4224 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4225 " starting at " HR_FORMAT,
4226 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4227
4228 hr->remove_strong_code_root(_nm);
4229 }
4230 }
4231
4232 public:
4233 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4234 _g1h(g1h), _nm(nm) {}
4235
4236 void do_oop(oop* p) { do_oop_work(p); }
4237 void do_oop(narrowOop* p) { do_oop_work(p); }
4238 };
4239
4240 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4241 guarantee(nm != NULL, "sanity");
4242 RegisterNMethodOopClosure reg_cl(this, nm);
4243 nm->oops_do(®_cl);
4244 }
4245
4246 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4247 guarantee(nm != NULL, "sanity");
4248 UnregisterNMethodOopClosure reg_cl(this, nm);
4249 nm->oops_do(®_cl, true);
4250 }
4251
4252 void G1CollectedHeap::update_used_after_gc() {
4253 if (evacuation_failed()) {
4254 // Reset the G1EvacuationFailureALot counters and flags
4255 NOT_PRODUCT(reset_evacuation_should_fail();)
4256
4257 set_used(recalculate_used());
4258
4259 if (_archive_allocator != NULL) {
4260 _archive_allocator->clear_used();
4261 }
4262 for (uint i = 0; i < ParallelGCThreads; i++) {
4263 if (_evacuation_failed_info_array[i].has_failed()) {
4264 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4265 }
4266 }
4267 } else {
4268 // The "used" of the the collection set have already been subtracted
4269 // when they were freed. Add in the bytes used.
4270 increase_used(_bytes_used_during_gc);
4271 }
4272 }
4273
4274 void G1CollectedHeap::reset_hot_card_cache() {
4275 _hot_card_cache->reset_hot_cache();
4276 _hot_card_cache->set_use_cache(true);
4277 }
4278
4279 void G1CollectedHeap::purge_code_root_memory() {
4280 G1CodeRootSet::purge();
4281 }
4282
4283 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4284 G1CollectedHeap* _g1h;
4285
4286 public:
4287 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4288 _g1h(g1h) {}
4289
4290 void do_code_blob(CodeBlob* cb) {
4291 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4292 if (nm == NULL) {
4293 return;
4294 }
4295
4296 _g1h->register_nmethod(nm);
4297 }
4298 };
4299
4300 void G1CollectedHeap::rebuild_strong_code_roots() {
4301 RebuildStrongCodeRootClosure blob_cl(this);
4302 CodeCache::blobs_do(&blob_cl);
4303 }
4304
4305 void G1CollectedHeap::initialize_serviceability() {
4306 _g1mm->initialize_serviceability();
4307 }
4308
4309 MemoryUsage G1CollectedHeap::memory_usage() {
4310 return _g1mm->memory_usage();
4311 }
4312
4313 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4314 return _g1mm->memory_managers();
4315 }
4316
4317 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4318 return _g1mm->memory_pools();
4319 }