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/slidingForwarding.hpp"
86 #include "gc/shared/suspendibleThreadSet.hpp"
87 #include "gc/shared/referenceProcessor.inline.hpp"
88 #include "gc/shared/taskTerminator.hpp"
89 #include "gc/shared/taskqueue.inline.hpp"
90 #include "gc/shared/tlab_globals.hpp"
91 #include "gc/shared/weakProcessor.inline.hpp"
92 #include "gc/shared/workerPolicy.hpp"
93 #include "logging/log.hpp"
94 #include "memory/allocation.hpp"
95 #include "memory/iterator.hpp"
96 #include "memory/heapInspection.hpp"
97 #include "memory/metaspaceUtils.hpp"
98 #include "memory/resourceArea.hpp"
99 #include "memory/universe.hpp"
100 #include "oops/access.inline.hpp"
101 #include "oops/compressedOops.inline.hpp"
102 #include "oops/oop.inline.hpp"
103 #include "runtime/atomic.hpp"
104 #include "runtime/handles.inline.hpp"
105 #include "runtime/init.hpp"
106 #include "runtime/java.hpp"
107 #include "runtime/orderAccess.hpp"
108 #include "runtime/threadSMR.hpp"
109 #include "runtime/vmThread.hpp"
110 #include "utilities/align.hpp"
111 #include "utilities/autoRestore.hpp"
112 #include "utilities/bitMap.inline.hpp"
113 #include "utilities/globalDefinitions.hpp"
114 #include "utilities/stack.inline.hpp"
115
116 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
117
118 // INVARIANTS/NOTES
119 //
120 // All allocation activity covered by the G1CollectedHeap interface is
121 // serialized by acquiring the HeapLock. This happens in mem_allocate
122 // and allocate_new_tlab, which are the "entry" points to the
123 // allocation code from the rest of the JVM. (Note that this does not
124 // apply to TLAB allocation, which is not part of this interface: it
125 // is done by clients of this interface.)
126
127 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
128 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
129 }
130
131 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
132 // The from card cache is not the memory that is actually committed. So we cannot
133 // take advantage of the zero_filled parameter.
134 reset_from_card_cache(start_idx, num_regions);
135 }
136
137 Tickspan G1CollectedHeap::run_task_timed(AbstractGangTask* task) {
138 Ticks start = Ticks::now();
139 workers()->run_task(task);
140 return Ticks::now() - start;
141 }
142
143 void G1CollectedHeap::run_batch_task(G1BatchedGangTask* cl) {
144 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
145 cl->set_max_workers(num_workers);
146 workers()->run_task(cl, num_workers);
147 }
148
149 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
150 MemRegion mr) {
151 return new HeapRegion(hrs_index, bot(), mr);
152 }
153
154 // Private methods.
155
156 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
157 HeapRegionType type,
158 bool do_expand,
159 uint node_index) {
160 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
161 "the only time we use this to allocate a humongous region is "
162 "when we are allocating a single humongous region");
163
164 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
165
166 if (res == NULL && do_expand && _expand_heap_after_alloc_failure) {
167 // Currently, only attempts to allocate GC alloc regions set
168 // do_expand to true. So, we should only reach here during a
169 // safepoint. If this assumption changes we might have to
170 // reconsider the use of _expand_heap_after_alloc_failure.
171 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
172
173 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
174 word_size * HeapWordSize);
175
176 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
177 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
178 word_size * HeapWordSize);
179 if (expand_single_region(node_index)) {
180 // Given that expand_single_region() succeeded in expanding the heap, and we
181 // always expand the heap by an amount aligned to the heap
182 // region size, the free list should in theory not be empty.
183 // In either case allocate_free_region() will check for NULL.
184 res = _hrm.allocate_free_region(type, node_index);
185 } else {
186 _expand_heap_after_alloc_failure = false;
187 }
188 }
189 return res;
190 }
191
192 HeapWord*
193 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
194 uint num_regions,
195 size_t word_size) {
196 assert(first_hr != NULL, "pre-condition");
197 assert(is_humongous(word_size), "word_size should be humongous");
198 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
199
200 // Index of last region in the series.
201 uint first = first_hr->hrm_index();
202 uint last = first + num_regions - 1;
203
204 // We need to initialize the region(s) we just discovered. This is
205 // a bit tricky given that it can happen concurrently with
206 // refinement threads refining cards on these regions and
207 // potentially wanting to refine the BOT as they are scanning
208 // those cards (this can happen shortly after a cleanup; see CR
209 // 6991377). So we have to set up the region(s) carefully and in
210 // a specific order.
211
212 // The word size sum of all the regions we will allocate.
213 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
214 assert(word_size <= word_size_sum, "sanity");
215
216 // The passed in hr will be the "starts humongous" region. The header
217 // of the new object will be placed at the bottom of this region.
218 HeapWord* new_obj = first_hr->bottom();
219 // This will be the new top of the new object.
220 HeapWord* obj_top = new_obj + word_size;
221
222 // First, we need to zero the header of the space that we will be
223 // allocating. When we update top further down, some refinement
224 // threads might try to scan the region. By zeroing the header we
225 // ensure that any thread that will try to scan the region will
226 // come across the zero klass word and bail out.
227 //
228 // NOTE: It would not have been correct to have used
229 // CollectedHeap::fill_with_object() and make the space look like
230 // an int array. The thread that is doing the allocation will
231 // later update the object header to a potentially different array
232 // type and, for a very short period of time, the klass and length
233 // fields will be inconsistent. This could cause a refinement
234 // thread to calculate the object size incorrectly.
235 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
236
237 // Next, pad out the unused tail of the last region with filler
238 // objects, for improved usage accounting.
239 // How many words we use for filler objects.
240 size_t word_fill_size = word_size_sum - word_size;
241
242 // How many words memory we "waste" which cannot hold a filler object.
243 size_t words_not_fillable = 0;
244
245 if (word_fill_size >= min_fill_size()) {
246 fill_with_objects(obj_top, word_fill_size);
247 } else if (word_fill_size > 0) {
248 // We have space to fill, but we cannot fit an object there.
249 words_not_fillable = word_fill_size;
250 word_fill_size = 0;
251 }
252
253 // We will set up the first region as "starts humongous". This
254 // will also update the BOT covering all the regions to reflect
255 // that there is a single object that starts at the bottom of the
256 // first region.
257 first_hr->set_starts_humongous(obj_top, word_fill_size);
258 _policy->remset_tracker()->update_at_allocate(first_hr);
259 // Then, if there are any, we will set up the "continues
260 // humongous" regions.
261 HeapRegion* hr = NULL;
262 for (uint i = first + 1; i <= last; ++i) {
263 hr = region_at(i);
264 hr->set_continues_humongous(first_hr);
265 _policy->remset_tracker()->update_at_allocate(hr);
266 }
267
268 // Up to this point no concurrent thread would have been able to
269 // do any scanning on any region in this series. All the top
270 // fields still point to bottom, so the intersection between
271 // [bottom,top] and [card_start,card_end] will be empty. Before we
272 // update the top fields, we'll do a storestore to make sure that
273 // no thread sees the update to top before the zeroing of the
274 // object header and the BOT initialization.
275 OrderAccess::storestore();
276
277 // Now, we will update the top fields of the "continues humongous"
278 // regions except the last one.
279 for (uint i = first; i < last; ++i) {
280 hr = region_at(i);
281 hr->set_top(hr->end());
282 }
283
284 hr = region_at(last);
285 // If we cannot fit a filler object, we must set top to the end
286 // of the humongous object, otherwise we cannot iterate the heap
287 // and the BOT will not be complete.
288 hr->set_top(hr->end() - words_not_fillable);
289
290 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
291 "obj_top should be in last region");
292
293 _verifier->check_bitmaps("Humongous Region Allocation", first_hr);
294
295 assert(words_not_fillable == 0 ||
296 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
297 "Miscalculation in humongous allocation");
298
299 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
300
301 for (uint i = first; i <= last; ++i) {
302 hr = region_at(i);
303 _humongous_set.add(hr);
304 _hr_printer.alloc(hr);
305 }
306
307 return new_obj;
308 }
309
310 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
311 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
312 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
313 }
314
315 // If could fit into free regions w/o expansion, try.
316 // Otherwise, if can expand, do so.
317 // Otherwise, if using ex regions might help, try with ex given back.
318 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
319 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
320
321 _verifier->verify_region_sets_optional();
322
323 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
324
325 // Policy: First try to allocate a humongous object in the free list.
326 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
327 if (humongous_start == NULL) {
328 // Policy: We could not find enough regions for the humongous object in the
329 // free list. Look through the heap to find a mix of free and uncommitted regions.
330 // If so, expand the heap and allocate the humongous object.
331 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
332 if (humongous_start != NULL) {
333 // We managed to find a region by expanding the heap.
334 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
335 word_size * HeapWordSize);
336 policy()->record_new_heap_size(num_regions());
337 } else {
338 // Policy: Potentially trigger a defragmentation GC.
339 }
340 }
341
342 HeapWord* result = NULL;
343 if (humongous_start != NULL) {
344 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
345 assert(result != NULL, "it should always return a valid result");
346
347 // A successful humongous object allocation changes the used space
348 // information of the old generation so we need to recalculate the
349 // sizes and update the jstat counters here.
350 g1mm()->update_sizes();
351 }
352
353 _verifier->verify_region_sets_optional();
354
355 return result;
356 }
357
358 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
359 size_t requested_size,
360 size_t* actual_size) {
361 assert_heap_not_locked_and_not_at_safepoint();
362 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
363
364 return attempt_allocation(min_size, requested_size, actual_size);
365 }
366
367 HeapWord*
368 G1CollectedHeap::mem_allocate(size_t word_size,
369 bool* gc_overhead_limit_was_exceeded) {
370 assert_heap_not_locked_and_not_at_safepoint();
371
372 if (is_humongous(word_size)) {
373 return attempt_allocation_humongous(word_size);
374 }
375 size_t dummy = 0;
376 return attempt_allocation(word_size, word_size, &dummy);
377 }
378
379 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
380 ResourceMark rm; // For retrieving the thread names in log messages.
381
382 // Make sure you read the note in attempt_allocation_humongous().
383
384 assert_heap_not_locked_and_not_at_safepoint();
385 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
386 "be called for humongous allocation requests");
387
388 // We should only get here after the first-level allocation attempt
389 // (attempt_allocation()) failed to allocate.
390
391 // We will loop until a) we manage to successfully perform the
392 // allocation or b) we successfully schedule a collection which
393 // fails to perform the allocation. b) is the only case when we'll
394 // return NULL.
395 HeapWord* result = NULL;
396 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
397 bool should_try_gc;
398 bool preventive_collection_required = false;
399 uint gc_count_before;
400
401 {
402 MutexLocker x(Heap_lock);
403
404 // Now that we have the lock, we first retry the allocation in case another
405 // thread changed the region while we were waiting to acquire the lock.
406 size_t actual_size;
407 result = _allocator->attempt_allocation(word_size, word_size, &actual_size);
408 if (result != NULL) {
409 return result;
410 }
411
412 preventive_collection_required = policy()->preventive_collection_required(1);
413 if (!preventive_collection_required) {
414 // We've already attempted a lock-free allocation above, so we don't want to
415 // do it again. Let's jump straight to replacing the active region.
416 result = _allocator->attempt_allocation_using_new_region(word_size);
417 if (result != NULL) {
418 return result;
419 }
420
421 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
422 // This is different to when only GCLocker::needs_gc() is set: try to avoid
423 // waiting because the GCLocker is active to not wait too long.
424 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
425 // No need for an ergo message here, can_expand_young_list() does this when
426 // it returns true.
427 result = _allocator->attempt_allocation_force(word_size);
428 if (result != NULL) {
429 return result;
430 }
431 }
432 }
433
434 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
435 // the GCLocker initiated GC has been performed and then retry. This includes
436 // the case when the GC Locker is not active but has not been performed.
437 should_try_gc = !GCLocker::needs_gc();
438 // Read the GC count while still holding the Heap_lock.
439 gc_count_before = total_collections();
440 }
441
442 if (should_try_gc) {
443 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
444 : GCCause::_g1_inc_collection_pause;
445 bool succeeded;
446 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
447 if (result != NULL) {
448 assert(succeeded, "only way to get back a non-NULL result");
449 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
450 Thread::current()->name(), p2i(result));
451 return result;
452 }
453
454 if (succeeded) {
455 // We successfully scheduled a collection which failed to allocate. No
456 // point in trying to allocate further. We'll just return NULL.
457 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
458 SIZE_FORMAT " words", Thread::current()->name(), word_size);
459 return NULL;
460 }
461 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
462 Thread::current()->name(), word_size);
463 } else {
464 // Failed to schedule a collection.
465 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
466 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
467 SIZE_FORMAT " words", Thread::current()->name(), word_size);
468 return NULL;
469 }
470 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
471 // The GCLocker is either active or the GCLocker initiated
472 // GC has not yet been performed. Stall until it is and
473 // then retry the allocation.
474 GCLocker::stall_until_clear();
475 gclocker_retry_count += 1;
476 }
477
478 // We can reach here if we were unsuccessful in scheduling a
479 // collection (because another thread beat us to it) or if we were
480 // stalled due to the GC locker. In either can we should retry the
481 // allocation attempt in case another thread successfully
482 // performed a collection and reclaimed enough space. We do the
483 // first attempt (without holding the Heap_lock) here and the
484 // follow-on attempt will be at the start of the next loop
485 // iteration (after taking the Heap_lock).
486 size_t dummy = 0;
487 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
488 if (result != NULL) {
489 return result;
490 }
491
492 // Give a warning if we seem to be looping forever.
493 if ((QueuedAllocationWarningCount > 0) &&
494 (try_count % QueuedAllocationWarningCount == 0)) {
495 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
496 Thread::current()->name(), try_count, word_size);
497 }
498 }
499
500 ShouldNotReachHere();
501 return NULL;
502 }
503
504 void G1CollectedHeap::begin_archive_alloc_range(bool open) {
505 assert_at_safepoint_on_vm_thread();
506 if (_archive_allocator == NULL) {
507 _archive_allocator = G1ArchiveAllocator::create_allocator(this, open);
508 }
509 }
510
511 bool G1CollectedHeap::is_archive_alloc_too_large(size_t word_size) {
512 // Allocations in archive regions cannot be of a size that would be considered
513 // humongous even for a minimum-sized region, because G1 region sizes/boundaries
514 // may be different at archive-restore time.
515 return word_size >= humongous_threshold_for(HeapRegion::min_region_size_in_words());
516 }
517
518 HeapWord* G1CollectedHeap::archive_mem_allocate(size_t word_size) {
519 assert_at_safepoint_on_vm_thread();
520 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
521 if (is_archive_alloc_too_large(word_size)) {
522 return NULL;
523 }
524 return _archive_allocator->archive_mem_allocate(word_size);
525 }
526
527 void G1CollectedHeap::end_archive_alloc_range(GrowableArray<MemRegion>* ranges,
528 size_t end_alignment_in_bytes) {
529 assert_at_safepoint_on_vm_thread();
530 assert(_archive_allocator != NULL, "_archive_allocator not initialized");
531
532 // Call complete_archive to do the real work, filling in the MemRegion
533 // array with the archive regions.
534 _archive_allocator->complete_archive(ranges, end_alignment_in_bytes);
535 delete _archive_allocator;
536 _archive_allocator = NULL;
537 }
538
539 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
540 assert(ranges != NULL, "MemRegion array NULL");
541 assert(count != 0, "No MemRegions provided");
542 MemRegion reserved = _hrm.reserved();
543 for (size_t i = 0; i < count; i++) {
544 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
545 return false;
546 }
547 }
548 return true;
549 }
550
551 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
552 size_t count,
553 bool open) {
554 assert(!is_init_completed(), "Expect to be called at JVM init time");
555 assert(ranges != NULL, "MemRegion array NULL");
556 assert(count != 0, "No MemRegions provided");
557 MutexLocker x(Heap_lock);
558
559 MemRegion reserved = _hrm.reserved();
560 HeapWord* prev_last_addr = NULL;
561 HeapRegion* prev_last_region = NULL;
562
563 // Temporarily disable pretouching of heap pages. This interface is used
564 // when mmap'ing archived heap data in, so pre-touching is wasted.
565 FlagSetting fs(AlwaysPreTouch, false);
566
567 // For each specified MemRegion range, allocate the corresponding G1
568 // regions and mark them as archive regions. We expect the ranges
569 // in ascending starting address order, without overlap.
570 for (size_t i = 0; i < count; i++) {
571 MemRegion curr_range = ranges[i];
572 HeapWord* start_address = curr_range.start();
573 size_t word_size = curr_range.word_size();
574 HeapWord* last_address = curr_range.last();
575 size_t commits = 0;
576
577 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
578 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
579 p2i(start_address), p2i(last_address));
580 guarantee(start_address > prev_last_addr,
581 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
582 p2i(start_address), p2i(prev_last_addr));
583 prev_last_addr = last_address;
584
585 // Check for ranges that start in the same G1 region in which the previous
586 // range ended, and adjust the start address so we don't try to allocate
587 // the same region again. If the current range is entirely within that
588 // region, skip it, just adjusting the recorded top.
589 HeapRegion* start_region = _hrm.addr_to_region(start_address);
590 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
591 start_address = start_region->end();
592 if (start_address > last_address) {
593 increase_used(word_size * HeapWordSize);
594 start_region->set_top(last_address + 1);
595 continue;
596 }
597 start_region->set_top(start_address);
598 curr_range = MemRegion(start_address, last_address + 1);
599 start_region = _hrm.addr_to_region(start_address);
600 }
601
602 // Perform the actual region allocation, exiting if it fails.
603 // Then note how much new space we have allocated.
604 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
605 return false;
606 }
607 increase_used(word_size * HeapWordSize);
608 if (commits != 0) {
609 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
610 HeapRegion::GrainWords * HeapWordSize * commits);
611
612 }
613
614 // Mark each G1 region touched by the range as archive, add it to
615 // the old set, and set top.
616 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
617 HeapRegion* last_region = _hrm.addr_to_region(last_address);
618 prev_last_region = last_region;
619
620 while (curr_region != NULL) {
621 assert(curr_region->is_empty() && !curr_region->is_pinned(),
622 "Region already in use (index %u)", curr_region->hrm_index());
623 if (open) {
624 curr_region->set_open_archive();
625 } else {
626 curr_region->set_closed_archive();
627 }
628 _hr_printer.alloc(curr_region);
629 _archive_set.add(curr_region);
630 HeapWord* top;
631 HeapRegion* next_region;
632 if (curr_region != last_region) {
633 top = curr_region->end();
634 next_region = _hrm.next_region_in_heap(curr_region);
635 } else {
636 top = last_address + 1;
637 next_region = NULL;
638 }
639 curr_region->set_top(top);
640 curr_region = next_region;
641 }
642 }
643 return true;
644 }
645
646 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
647 assert(!is_init_completed(), "Expect to be called at JVM init time");
648 assert(ranges != NULL, "MemRegion array NULL");
649 assert(count != 0, "No MemRegions provided");
650 MemRegion reserved = _hrm.reserved();
651 HeapWord *prev_last_addr = NULL;
652 HeapRegion* prev_last_region = NULL;
653
654 // For each MemRegion, create filler objects, if needed, in the G1 regions
655 // that contain the address range. The address range actually within the
656 // MemRegion will not be modified. That is assumed to have been initialized
657 // elsewhere, probably via an mmap of archived heap data.
658 MutexLocker x(Heap_lock);
659 for (size_t i = 0; i < count; i++) {
660 HeapWord* start_address = ranges[i].start();
661 HeapWord* last_address = ranges[i].last();
662
663 assert(reserved.contains(start_address) && reserved.contains(last_address),
664 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
665 p2i(start_address), p2i(last_address));
666 assert(start_address > prev_last_addr,
667 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
668 p2i(start_address), p2i(prev_last_addr));
669
670 HeapRegion* start_region = _hrm.addr_to_region(start_address);
671 HeapRegion* last_region = _hrm.addr_to_region(last_address);
672 HeapWord* bottom_address = start_region->bottom();
673
674 // Check for a range beginning in the same region in which the
675 // previous one ended.
676 if (start_region == prev_last_region) {
677 bottom_address = prev_last_addr + 1;
678 }
679
680 // Verify that the regions were all marked as archive regions by
681 // alloc_archive_regions.
682 HeapRegion* curr_region = start_region;
683 while (curr_region != NULL) {
684 guarantee(curr_region->is_archive(),
685 "Expected archive region at index %u", curr_region->hrm_index());
686 if (curr_region != last_region) {
687 curr_region = _hrm.next_region_in_heap(curr_region);
688 } else {
689 curr_region = NULL;
690 }
691 }
692
693 prev_last_addr = last_address;
694 prev_last_region = last_region;
695
696 // Fill the memory below the allocated range with dummy object(s),
697 // if the region bottom does not match the range start, or if the previous
698 // range ended within the same G1 region, and there is a gap.
699 assert(start_address >= bottom_address, "bottom address should not be greater than start address");
700 if (start_address > bottom_address) {
701 size_t fill_size = pointer_delta(start_address, bottom_address);
702 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
703 increase_used(fill_size * HeapWordSize);
704 }
705 }
706 }
707
708 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
709 size_t desired_word_size,
710 size_t* actual_word_size) {
711 assert_heap_not_locked_and_not_at_safepoint();
712 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
713 "be called for humongous allocation requests");
714
715 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
716
717 if (result == NULL) {
718 *actual_word_size = desired_word_size;
719 result = attempt_allocation_slow(desired_word_size);
720 }
721
722 assert_heap_not_locked();
723 if (result != NULL) {
724 assert(*actual_word_size != 0, "Actual size must have been set here");
725 dirty_young_block(result, *actual_word_size);
726 } else {
727 *actual_word_size = 0;
728 }
729
730 return result;
731 }
732
733 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion* ranges, size_t count) {
734 assert(!is_init_completed(), "Expect to be called at JVM init time");
735 assert(ranges != NULL, "MemRegion array NULL");
736 assert(count != 0, "No MemRegions provided");
737
738 HeapWord* st = ranges[0].start();
739 HeapWord* last = ranges[count-1].last();
740 HeapRegion* hr_st = _hrm.addr_to_region(st);
741 HeapRegion* hr_last = _hrm.addr_to_region(last);
742
743 HeapRegion* hr_curr = hr_st;
744 while (hr_curr != NULL) {
745 hr_curr->update_bot();
746 if (hr_curr != hr_last) {
747 hr_curr = _hrm.next_region_in_heap(hr_curr);
748 } else {
749 hr_curr = NULL;
750 }
751 }
752 }
753
754 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
755 assert(!is_init_completed(), "Expect to be called at JVM init time");
756 assert(ranges != NULL, "MemRegion array NULL");
757 assert(count != 0, "No MemRegions provided");
758 MemRegion reserved = _hrm.reserved();
759 HeapWord* prev_last_addr = NULL;
760 HeapRegion* prev_last_region = NULL;
761 size_t size_used = 0;
762 uint shrink_count = 0;
763
764 // For each Memregion, free the G1 regions that constitute it, and
765 // notify mark-sweep that the range is no longer to be considered 'archive.'
766 MutexLocker x(Heap_lock);
767 for (size_t i = 0; i < count; i++) {
768 HeapWord* start_address = ranges[i].start();
769 HeapWord* last_address = ranges[i].last();
770
771 assert(reserved.contains(start_address) && reserved.contains(last_address),
772 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
773 p2i(start_address), p2i(last_address));
774 assert(start_address > prev_last_addr,
775 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
776 p2i(start_address), p2i(prev_last_addr));
777 size_used += ranges[i].byte_size();
778 prev_last_addr = last_address;
779
780 HeapRegion* start_region = _hrm.addr_to_region(start_address);
781 HeapRegion* last_region = _hrm.addr_to_region(last_address);
782
783 // Check for ranges that start in the same G1 region in which the previous
784 // range ended, and adjust the start address so we don't try to free
785 // the same region again. If the current range is entirely within that
786 // region, skip it.
787 if (start_region == prev_last_region) {
788 start_address = start_region->end();
789 if (start_address > last_address) {
790 continue;
791 }
792 start_region = _hrm.addr_to_region(start_address);
793 }
794 prev_last_region = last_region;
795
796 // After verifying that each region was marked as an archive region by
797 // alloc_archive_regions, set it free and empty and uncommit it.
798 HeapRegion* curr_region = start_region;
799 while (curr_region != NULL) {
800 guarantee(curr_region->is_archive(),
801 "Expected archive region at index %u", curr_region->hrm_index());
802 uint curr_index = curr_region->hrm_index();
803 _archive_set.remove(curr_region);
804 curr_region->set_free();
805 curr_region->set_top(curr_region->bottom());
806 if (curr_region != last_region) {
807 curr_region = _hrm.next_region_in_heap(curr_region);
808 } else {
809 curr_region = NULL;
810 }
811
812 _hrm.shrink_at(curr_index, 1);
813 shrink_count++;
814 }
815 }
816
817 if (shrink_count != 0) {
818 log_debug(gc, ergo, heap)("Attempt heap shrinking (archive regions). Total size: " SIZE_FORMAT "B",
819 HeapRegion::GrainWords * HeapWordSize * shrink_count);
820 // Explicit uncommit.
821 uncommit_regions(shrink_count);
822 }
823 decrease_used(size_used);
824 }
825
826 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
827 ResourceMark rm; // For retrieving the thread names in log messages.
828
829 // The structure of this method has a lot of similarities to
830 // attempt_allocation_slow(). The reason these two were not merged
831 // into a single one is that such a method would require several "if
832 // allocation is not humongous do this, otherwise do that"
833 // conditional paths which would obscure its flow. In fact, an early
834 // version of this code did use a unified method which was harder to
835 // follow and, as a result, it had subtle bugs that were hard to
836 // track down. So keeping these two methods separate allows each to
837 // be more readable. It will be good to keep these two in sync as
838 // much as possible.
839
840 assert_heap_not_locked_and_not_at_safepoint();
841 assert(is_humongous(word_size), "attempt_allocation_humongous() "
842 "should only be called for humongous allocations");
843
844 // Humongous objects can exhaust the heap quickly, so we should check if we
845 // need to start a marking cycle at each humongous object allocation. We do
846 // the check before we do the actual allocation. The reason for doing it
847 // before the allocation is that we avoid having to keep track of the newly
848 // allocated memory while we do a GC.
849 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
850 word_size)) {
851 collect(GCCause::_g1_humongous_allocation);
852 }
853
854 // We will loop until a) we manage to successfully perform the
855 // allocation or b) we successfully schedule a collection which
856 // fails to perform the allocation. b) is the only case when we'll
857 // return NULL.
858 HeapWord* result = NULL;
859 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
860 bool should_try_gc;
861 bool preventive_collection_required = false;
862 uint gc_count_before;
863
864
865 {
866 MutexLocker x(Heap_lock);
867
868 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
869 preventive_collection_required = policy()->preventive_collection_required((uint)size_in_regions);
870 if (!preventive_collection_required) {
871 // Given that humongous objects are not allocated in young
872 // regions, we'll first try to do the allocation without doing a
873 // collection hoping that there's enough space in the heap.
874 result = humongous_obj_allocate(word_size);
875 if (result != NULL) {
876 policy()->old_gen_alloc_tracker()->
877 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
878 return result;
879 }
880 }
881
882 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
883 // the GCLocker initiated GC has been performed and then retry. This includes
884 // the case when the GC Locker is not active but has not been performed.
885 should_try_gc = !GCLocker::needs_gc();
886 // Read the GC count while still holding the Heap_lock.
887 gc_count_before = total_collections();
888 }
889
890 if (should_try_gc) {
891 GCCause::Cause gc_cause = preventive_collection_required ? GCCause::_g1_preventive_collection
892 : GCCause::_g1_humongous_allocation;
893 bool succeeded;
894 result = do_collection_pause(word_size, gc_count_before, &succeeded, gc_cause);
895 if (result != NULL) {
896 assert(succeeded, "only way to get back a non-NULL result");
897 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
898 Thread::current()->name(), p2i(result));
899 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
900 policy()->old_gen_alloc_tracker()->
901 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
902 return result;
903 }
904
905 if (succeeded) {
906 // We successfully scheduled a collection which failed to allocate. No
907 // point in trying to allocate further. We'll just return NULL.
908 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
909 SIZE_FORMAT " words", Thread::current()->name(), word_size);
910 return NULL;
911 }
912 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
913 Thread::current()->name(), word_size);
914 } else {
915 // Failed to schedule a collection.
916 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
917 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
918 SIZE_FORMAT " words", Thread::current()->name(), word_size);
919 return NULL;
920 }
921 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
922 // The GCLocker is either active or the GCLocker initiated
923 // GC has not yet been performed. Stall until it is and
924 // then retry the allocation.
925 GCLocker::stall_until_clear();
926 gclocker_retry_count += 1;
927 }
928
929
930 // We can reach here if we were unsuccessful in scheduling a
931 // collection (because another thread beat us to it) or if we were
932 // stalled due to the GC locker. In either can we should retry the
933 // allocation attempt in case another thread successfully
934 // performed a collection and reclaimed enough space.
935 // Humongous object allocation always needs a lock, so we wait for the retry
936 // in the next iteration of the loop, unlike for the regular iteration case.
937 // Give a warning if we seem to be looping forever.
938
939 if ((QueuedAllocationWarningCount > 0) &&
940 (try_count % QueuedAllocationWarningCount == 0)) {
941 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
942 Thread::current()->name(), try_count, word_size);
943 }
944 }
945
946 ShouldNotReachHere();
947 return NULL;
948 }
949
950 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
951 bool expect_null_mutator_alloc_region) {
952 assert_at_safepoint_on_vm_thread();
953 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
954 "the current alloc region was unexpectedly found to be non-NULL");
955
956 if (!is_humongous(word_size)) {
957 return _allocator->attempt_allocation_locked(word_size);
958 } else {
959 HeapWord* result = humongous_obj_allocate(word_size);
960 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
961 collector_state()->set_initiate_conc_mark_if_possible(true);
962 }
963 return result;
964 }
965
966 ShouldNotReachHere();
967 }
968
969 class PostCompactionPrinterClosure: public HeapRegionClosure {
970 private:
971 G1HRPrinter* _hr_printer;
972 public:
973 bool do_heap_region(HeapRegion* hr) {
974 assert(!hr->is_young(), "not expecting to find young regions");
975 _hr_printer->post_compaction(hr);
976 return false;
977 }
978
979 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
980 : _hr_printer(hr_printer) { }
981 };
982
983 void G1CollectedHeap::print_hrm_post_compaction() {
984 if (_hr_printer.is_active()) {
985 PostCompactionPrinterClosure cl(hr_printer());
986 heap_region_iterate(&cl);
987 }
988 }
989
990 void G1CollectedHeap::abort_concurrent_cycle() {
991 // If we start the compaction before the CM threads finish
992 // scanning the root regions we might trip them over as we'll
993 // be moving objects / updating references. So let's wait until
994 // they are done. By telling them to abort, they should complete
995 // early.
996 _cm->root_regions()->abort();
997 _cm->root_regions()->wait_until_scan_finished();
998
999 // Disable discovery and empty the discovered lists
1000 // for the CM ref processor.
1001 _ref_processor_cm->disable_discovery();
1002 _ref_processor_cm->abandon_partial_discovery();
1003 _ref_processor_cm->verify_no_references_recorded();
1004
1005 // Abandon current iterations of concurrent marking and concurrent
1006 // refinement, if any are in progress.
1007 concurrent_mark()->concurrent_cycle_abort();
1008 }
1009
1010 void G1CollectedHeap::prepare_heap_for_full_collection() {
1011 // Make sure we'll choose a new allocation region afterwards.
1012 _allocator->release_mutator_alloc_regions();
1013 _allocator->abandon_gc_alloc_regions();
1014
1015 // We may have added regions to the current incremental collection
1016 // set between the last GC or pause and now. We need to clear the
1017 // incremental collection set and then start rebuilding it afresh
1018 // after this full GC.
1019 abandon_collection_set(collection_set());
1020
1021 _hrm.remove_all_free_regions();
1022 }
1023
1024 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
1025 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
1026 assert_used_and_recalculate_used_equal(this);
1027 _verifier->verify_region_sets_optional();
1028 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
1029 _verifier->check_bitmaps("Full GC Start");
1030 }
1031
1032 void G1CollectedHeap::prepare_heap_for_mutators() {
1033 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1034 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1035 DEBUG_ONLY(MetaspaceUtils::verify();)
1036
1037 // Prepare heap for normal collections.
1038 assert(num_free_regions() == 0, "we should not have added any free regions");
1039 rebuild_region_sets(false /* free_list_only */);
1040 abort_refinement();
1041 resize_heap_if_necessary();
1042 uncommit_regions_if_necessary();
1043
1044 // Rebuild the strong code root lists for each region
1045 rebuild_strong_code_roots();
1046
1047 // Purge code root memory
1048 purge_code_root_memory();
1049
1050 // Start a new incremental collection set for the next pause
1051 start_new_collection_set();
1052
1053 _allocator->init_mutator_alloc_regions();
1054
1055 // Post collection state updates.
1056 MetaspaceGC::compute_new_size();
1057 }
1058
1059 void G1CollectedHeap::abort_refinement() {
1060 if (_hot_card_cache->use_cache()) {
1061 _hot_card_cache->reset_hot_cache();
1062 }
1063
1064 // Discard all remembered set updates and reset refinement statistics.
1065 G1BarrierSet::dirty_card_queue_set().abandon_logs();
1066 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1067 "DCQS should be empty");
1068 concurrent_refine()->get_and_reset_refinement_stats();
1069 }
1070
1071 void G1CollectedHeap::verify_after_full_collection() {
1072 _hrm.verify_optional();
1073 _verifier->verify_region_sets_optional();
1074 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1075
1076 // This call implicitly verifies that the next bitmap is clear after Full GC.
1077 _verifier->check_bitmaps("Full GC End");
1078
1079 // At this point there should be no regions in the
1080 // entire heap tagged as young.
1081 assert(check_young_list_empty(), "young list should be empty at this point");
1082
1083 // Note: since we've just done a full GC, concurrent
1084 // marking is no longer active. Therefore we need not
1085 // re-enable reference discovery for the CM ref processor.
1086 // That will be done at the start of the next marking cycle.
1087 // We also know that the STW processor should no longer
1088 // discover any new references.
1089 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1090 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1091 _ref_processor_stw->verify_no_references_recorded();
1092 _ref_processor_cm->verify_no_references_recorded();
1093 }
1094
1095 void G1CollectedHeap::print_heap_after_full_collection(G1HeapTransition* heap_transition) {
1096 // Post collection logging.
1097 // We should do this after we potentially resize the heap so
1098 // that all the COMMIT / UNCOMMIT events are generated before
1099 // the compaction events.
1100 print_hrm_post_compaction();
1101 heap_transition->print();
1102 print_heap_after_gc();
1103 print_heap_regions();
1104 }
1105
1106 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1107 bool clear_all_soft_refs,
1108 bool do_maximum_compaction) {
1109 assert_at_safepoint_on_vm_thread();
1110
1111 if (GCLocker::check_active_before_gc()) {
1112 // Full GC was not completed.
1113 return false;
1114 }
1115
1116 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1117 soft_ref_policy()->should_clear_all_soft_refs();
1118
1119 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs, do_maximum_compaction);
1120 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1121
1122 collector.prepare_collection();
1123 collector.collect();
1124 collector.complete_collection();
1125
1126 // Full collection was successfully completed.
1127 return true;
1128 }
1129
1130 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1131 // Currently, there is no facility in the do_full_collection(bool) API to notify
1132 // the caller that the collection did not succeed (e.g., because it was locked
1133 // out by the GC locker). So, right now, we'll ignore the return value.
1134 // When clear_all_soft_refs is set we want to do a maximum compaction
1135 // not leaving any dead wood.
1136 bool do_maximum_compaction = clear_all_soft_refs;
1137 bool dummy = do_full_collection(true, /* explicit_gc */
1138 clear_all_soft_refs,
1139 do_maximum_compaction);
1140 }
1141
1142 bool G1CollectedHeap::upgrade_to_full_collection() {
1143 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1144 log_info(gc, ergo)("Attempting full compaction clearing soft references");
1145 bool success = do_full_collection(false /* explicit gc */,
1146 true /* clear_all_soft_refs */,
1147 false /* do_maximum_compaction */);
1148 // do_full_collection only fails if blocked by GC locker and that can't
1149 // be the case here since we only call this when already completed one gc.
1150 assert(success, "invariant");
1151 return success;
1152 }
1153
1154 void G1CollectedHeap::resize_heap_if_necessary() {
1155 assert_at_safepoint_on_vm_thread();
1156
1157 bool should_expand;
1158 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1159
1160 if (resize_amount == 0) {
1161 return;
1162 } else if (should_expand) {
1163 expand(resize_amount, _workers);
1164 } else {
1165 shrink(resize_amount);
1166 }
1167 }
1168
1169 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1170 bool do_gc,
1171 bool maximum_compaction,
1172 bool expect_null_mutator_alloc_region,
1173 bool* gc_succeeded) {
1174 *gc_succeeded = true;
1175 // Let's attempt the allocation first.
1176 HeapWord* result =
1177 attempt_allocation_at_safepoint(word_size,
1178 expect_null_mutator_alloc_region);
1179 if (result != NULL) {
1180 return result;
1181 }
1182
1183 // In a G1 heap, we're supposed to keep allocation from failing by
1184 // incremental pauses. Therefore, at least for now, we'll favor
1185 // expansion over collection. (This might change in the future if we can
1186 // do something smarter than full collection to satisfy a failed alloc.)
1187 result = expand_and_allocate(word_size);
1188 if (result != NULL) {
1189 return result;
1190 }
1191
1192 if (do_gc) {
1193 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1194 // Expansion didn't work, we'll try to do a Full GC.
1195 // If maximum_compaction is set we clear all soft references and don't
1196 // allow any dead wood to be left on the heap.
1197 if (maximum_compaction) {
1198 log_info(gc, ergo)("Attempting maximum full compaction clearing soft references");
1199 } else {
1200 log_info(gc, ergo)("Attempting full compaction");
1201 }
1202 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1203 maximum_compaction /* clear_all_soft_refs */ ,
1204 maximum_compaction /* do_maximum_compaction */);
1205 }
1206
1207 return NULL;
1208 }
1209
1210 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1211 bool* succeeded) {
1212 assert_at_safepoint_on_vm_thread();
1213
1214 // Attempts to allocate followed by Full GC.
1215 HeapWord* result =
1216 satisfy_failed_allocation_helper(word_size,
1217 true, /* do_gc */
1218 false, /* maximum_collection */
1219 false, /* expect_null_mutator_alloc_region */
1220 succeeded);
1221
1222 if (result != NULL || !*succeeded) {
1223 return result;
1224 }
1225
1226 // Attempts to allocate followed by Full GC that will collect all soft references.
1227 result = satisfy_failed_allocation_helper(word_size,
1228 true, /* do_gc */
1229 true, /* maximum_collection */
1230 true, /* expect_null_mutator_alloc_region */
1231 succeeded);
1232
1233 if (result != NULL || !*succeeded) {
1234 return result;
1235 }
1236
1237 // Attempts to allocate, no GC
1238 result = satisfy_failed_allocation_helper(word_size,
1239 false, /* do_gc */
1240 false, /* maximum_collection */
1241 true, /* expect_null_mutator_alloc_region */
1242 succeeded);
1243
1244 if (result != NULL) {
1245 return result;
1246 }
1247
1248 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1249 "Flag should have been handled and cleared prior to this point");
1250
1251 // What else? We might try synchronous finalization later. If the total
1252 // space available is large enough for the allocation, then a more
1253 // complete compaction phase than we've tried so far might be
1254 // appropriate.
1255 return NULL;
1256 }
1257
1258 // Attempting to expand the heap sufficiently
1259 // to support an allocation of the given "word_size". If
1260 // successful, perform the allocation and return the address of the
1261 // allocated block, or else "NULL".
1262
1263 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1264 assert_at_safepoint_on_vm_thread();
1265
1266 _verifier->verify_region_sets_optional();
1267
1268 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1269 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1270 word_size * HeapWordSize);
1271
1272
1273 if (expand(expand_bytes, _workers)) {
1274 _hrm.verify_optional();
1275 _verifier->verify_region_sets_optional();
1276 return attempt_allocation_at_safepoint(word_size,
1277 false /* expect_null_mutator_alloc_region */);
1278 }
1279 return NULL;
1280 }
1281
1282 bool G1CollectedHeap::expand(size_t expand_bytes, WorkGang* pretouch_workers, double* expand_time_ms) {
1283 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1284 aligned_expand_bytes = align_up(aligned_expand_bytes,
1285 HeapRegion::GrainBytes);
1286
1287 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1288 expand_bytes, aligned_expand_bytes);
1289
1290 if (is_maximal_no_gc()) {
1291 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1292 return false;
1293 }
1294
1295 double expand_heap_start_time_sec = os::elapsedTime();
1296 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1297 assert(regions_to_expand > 0, "Must expand by at least one region");
1298
1299 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1300 if (expand_time_ms != NULL) {
1301 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1302 }
1303
1304 if (expanded_by > 0) {
1305 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1306 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1307 policy()->record_new_heap_size(num_regions());
1308 } else {
1309 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1310
1311 // The expansion of the virtual storage space was unsuccessful.
1312 // Let's see if it was because we ran out of swap.
1313 if (G1ExitOnExpansionFailure &&
1314 _hrm.available() >= regions_to_expand) {
1315 // We had head room...
1316 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1317 }
1318 }
1319 return regions_to_expand > 0;
1320 }
1321
1322 bool G1CollectedHeap::expand_single_region(uint node_index) {
1323 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1324
1325 if (expanded_by == 0) {
1326 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1327 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1328 return false;
1329 }
1330
1331 policy()->record_new_heap_size(num_regions());
1332 return true;
1333 }
1334
1335 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1336 size_t aligned_shrink_bytes =
1337 ReservedSpace::page_align_size_down(shrink_bytes);
1338 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1339 HeapRegion::GrainBytes);
1340 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1341
1342 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1343 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1344
1345 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",
1346 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1347 if (num_regions_removed > 0) {
1348 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1349 policy()->record_new_heap_size(num_regions());
1350 } else {
1351 log_debug(gc, ergo, heap)("Did not expand the heap (heap shrinking operation failed)");
1352 }
1353 }
1354
1355 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1356 _verifier->verify_region_sets_optional();
1357
1358 // We should only reach here at the end of a Full GC or during Remark which
1359 // means we should not not be holding to any GC alloc regions. The method
1360 // below will make sure of that and do any remaining clean up.
1361 _allocator->abandon_gc_alloc_regions();
1362
1363 // Instead of tearing down / rebuilding the free lists here, we
1364 // could instead use the remove_all_pending() method on free_list to
1365 // remove only the ones that we need to remove.
1366 _hrm.remove_all_free_regions();
1367 shrink_helper(shrink_bytes);
1368 rebuild_region_sets(true /* free_list_only */);
1369
1370 _hrm.verify_optional();
1371 _verifier->verify_region_sets_optional();
1372 }
1373
1374 class OldRegionSetChecker : public HeapRegionSetChecker {
1375 public:
1376 void check_mt_safety() {
1377 // Master Old Set MT safety protocol:
1378 // (a) If we're at a safepoint, operations on the master old set
1379 // should be invoked:
1380 // - by the VM thread (which will serialize them), or
1381 // - by the GC workers while holding the FreeList_lock, if we're
1382 // at a safepoint for an evacuation pause (this lock is taken
1383 // anyway when an GC alloc region is retired so that a new one
1384 // is allocated from the free list), or
1385 // - by the GC workers while holding the OldSets_lock, if we're at a
1386 // safepoint for a cleanup pause.
1387 // (b) If we're not at a safepoint, operations on the master old set
1388 // should be invoked while holding the Heap_lock.
1389
1390 if (SafepointSynchronize::is_at_safepoint()) {
1391 guarantee(Thread::current()->is_VM_thread() ||
1392 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1393 "master old set MT safety protocol at a safepoint");
1394 } else {
1395 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1396 }
1397 }
1398 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1399 const char* get_description() { return "Old Regions"; }
1400 };
1401
1402 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1403 public:
1404 void check_mt_safety() {
1405 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1406 "May only change archive regions during initialization or safepoint.");
1407 }
1408 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1409 const char* get_description() { return "Archive Regions"; }
1410 };
1411
1412 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1413 public:
1414 void check_mt_safety() {
1415 // Humongous Set MT safety protocol:
1416 // (a) If we're at a safepoint, operations on the master humongous
1417 // set should be invoked by either the VM thread (which will
1418 // serialize them) or by the GC workers while holding the
1419 // OldSets_lock.
1420 // (b) If we're not at a safepoint, operations on the master
1421 // humongous set should be invoked while holding the Heap_lock.
1422
1423 if (SafepointSynchronize::is_at_safepoint()) {
1424 guarantee(Thread::current()->is_VM_thread() ||
1425 OldSets_lock->owned_by_self(),
1426 "master humongous set MT safety protocol at a safepoint");
1427 } else {
1428 guarantee(Heap_lock->owned_by_self(),
1429 "master humongous set MT safety protocol outside a safepoint");
1430 }
1431 }
1432 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1433 const char* get_description() { return "Humongous Regions"; }
1434 };
1435
1436 G1CollectedHeap::G1CollectedHeap() :
1437 CollectedHeap(),
1438 _service_thread(NULL),
1439 _periodic_gc_task(NULL),
1440 _workers(NULL),
1441 _card_table(NULL),
1442 _collection_pause_end(Ticks::now()),
1443 _soft_ref_policy(),
1444 _old_set("Old Region Set", new OldRegionSetChecker()),
1445 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1446 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1447 _bot(NULL),
1448 _listener(),
1449 _numa(G1NUMA::create()),
1450 _hrm(),
1451 _allocator(NULL),
1452 _verifier(NULL),
1453 _summary_bytes_used(0),
1454 _bytes_used_during_gc(0),
1455 _archive_allocator(NULL),
1456 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1457 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1458 _expand_heap_after_alloc_failure(true),
1459 _g1mm(NULL),
1460 _humongous_reclaim_candidates(),
1461 _num_humongous_objects(0),
1462 _num_humongous_reclaim_candidates(0),
1463 _hr_printer(),
1464 _collector_state(),
1465 _old_marking_cycles_started(0),
1466 _old_marking_cycles_completed(0),
1467 _eden(),
1468 _survivor(),
1469 _gc_timer_stw(new (ResourceObj::C_HEAP, mtGC) STWGCTimer()),
1470 _gc_tracer_stw(new (ResourceObj::C_HEAP, mtGC) G1NewTracer()),
1471 _policy(new G1Policy(_gc_timer_stw)),
1472 _heap_sizing_policy(NULL),
1473 _collection_set(this, _policy),
1474 _hot_card_cache(NULL),
1475 _rem_set(NULL),
1476 _cm(NULL),
1477 _cm_thread(NULL),
1478 _cr(NULL),
1479 _task_queues(NULL),
1480 _num_regions_failed_evacuation(0),
1481 _regions_failed_evacuation(NULL),
1482 _evacuation_failed_info_array(NULL),
1483 _preserved_marks_set(true /* in_c_heap */),
1484 #ifndef PRODUCT
1485 _evacuation_failure_alot_for_current_gc(false),
1486 _evacuation_failure_alot_gc_number(0),
1487 _evacuation_failure_alot_count(0),
1488 #endif
1489 _ref_processor_stw(NULL),
1490 _is_alive_closure_stw(this),
1491 _is_subject_to_discovery_stw(this),
1492 _ref_processor_cm(NULL),
1493 _is_alive_closure_cm(this),
1494 _is_subject_to_discovery_cm(this),
1495 _region_attr() {
1496
1497 _verifier = new G1HeapVerifier(this);
1498
1499 _allocator = new G1Allocator(this);
1500
1501 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1502
1503 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1504
1505 // Override the default _filler_array_max_size so that no humongous filler
1506 // objects are created.
1507 _filler_array_max_size = _humongous_object_threshold_in_words;
1508
1509 uint n_queues = ParallelGCThreads;
1510 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1511
1512 _evacuation_failed_info_array = NEW_C_HEAP_ARRAY(EvacuationFailedInfo, n_queues, mtGC);
1513
1514 for (uint i = 0; i < n_queues; i++) {
1515 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1516 q->initialize();
1517 _task_queues->register_queue(i, q);
1518 ::new (&_evacuation_failed_info_array[i]) EvacuationFailedInfo();
1519 }
1520
1521 // Initialize the G1EvacuationFailureALot counters and flags.
1522 NOT_PRODUCT(reset_evacuation_should_fail();)
1523 _gc_tracer_stw->initialize();
1524
1525 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1526 }
1527
1528 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1529 size_t size,
1530 size_t translation_factor) {
1531 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1532 // Allocate a new reserved space, preferring to use large pages.
1533 ReservedSpace rs(size, preferred_page_size);
1534 size_t page_size = rs.page_size();
1535 G1RegionToSpaceMapper* result =
1536 G1RegionToSpaceMapper::create_mapper(rs,
1537 size,
1538 page_size,
1539 HeapRegion::GrainBytes,
1540 translation_factor,
1541 mtGC);
1542
1543 os::trace_page_sizes_for_requested_size(description,
1544 size,
1545 page_size,
1546 preferred_page_size,
1547 rs.base(),
1548 rs.size());
1549
1550 return result;
1551 }
1552
1553 jint G1CollectedHeap::initialize_concurrent_refinement() {
1554 jint ecode = JNI_OK;
1555 _cr = G1ConcurrentRefine::create(&ecode);
1556 return ecode;
1557 }
1558
1559 jint G1CollectedHeap::initialize_service_thread() {
1560 _service_thread = new G1ServiceThread();
1561 if (_service_thread->osthread() == NULL) {
1562 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1563 return JNI_ENOMEM;
1564 }
1565 return JNI_OK;
1566 }
1567
1568 jint G1CollectedHeap::initialize() {
1569
1570 // Necessary to satisfy locking discipline assertions.
1571
1572 MutexLocker x(Heap_lock);
1573
1574 // While there are no constraints in the GC code that HeapWordSize
1575 // be any particular value, there are multiple other areas in the
1576 // system which believe this to be true (e.g. oop->object_size in some
1577 // cases incorrectly returns the size in wordSize units rather than
1578 // HeapWordSize).
1579 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1580
1581 size_t init_byte_size = InitialHeapSize;
1582 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1583
1584 // Ensure that the sizes are properly aligned.
1585 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1586 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1587 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1588
1589 // Reserve the maximum.
1590
1591 // When compressed oops are enabled, the preferred heap base
1592 // is calculated by subtracting the requested size from the
1593 // 32Gb boundary and using the result as the base address for
1594 // heap reservation. If the requested size is not aligned to
1595 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1596 // into the ReservedHeapSpace constructor) then the actual
1597 // base of the reserved heap may end up differing from the
1598 // address that was requested (i.e. the preferred heap base).
1599 // If this happens then we could end up using a non-optimal
1600 // compressed oops mode.
1601
1602 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1603 HeapAlignment);
1604
1605 initialize_reserved_region(heap_rs);
1606
1607 // Create the barrier set for the entire reserved region.
1608 G1CardTable* ct = new G1CardTable(heap_rs.region());
1609 ct->initialize();
1610 G1BarrierSet* bs = new G1BarrierSet(ct);
1611 bs->initialize();
1612 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1613 BarrierSet::set_barrier_set(bs);
1614 _card_table = ct;
1615
1616 {
1617 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1618 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1619 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1620 }
1621
1622 // Create the hot card cache.
1623 _hot_card_cache = new G1HotCardCache(this);
1624
1625 // Create space mappers.
1626 size_t page_size = heap_rs.page_size();
1627 G1RegionToSpaceMapper* heap_storage =
1628 G1RegionToSpaceMapper::create_mapper(heap_rs,
1629 heap_rs.size(),
1630 page_size,
1631 HeapRegion::GrainBytes,
1632 1,
1633 mtJavaHeap);
1634 if(heap_storage == NULL) {
1635 vm_shutdown_during_initialization("Could not initialize G1 heap");
1636 return JNI_ERR;
1637 }
1638
1639 os::trace_page_sizes("Heap",
1640 MinHeapSize,
1641 reserved_byte_size,
1642 page_size,
1643 heap_rs.base(),
1644 heap_rs.size());
1645 heap_storage->set_mapping_changed_listener(&_listener);
1646
1647 // Create storage for the BOT, card table, card counts table (hot card cache) and the bitmaps.
1648 G1RegionToSpaceMapper* bot_storage =
1649 create_aux_memory_mapper("Block Offset Table",
1650 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1651 G1BlockOffsetTable::heap_map_factor());
1652
1653 G1RegionToSpaceMapper* cardtable_storage =
1654 create_aux_memory_mapper("Card Table",
1655 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1656 G1CardTable::heap_map_factor());
1657
1658 G1RegionToSpaceMapper* card_counts_storage =
1659 create_aux_memory_mapper("Card Counts Table",
1660 G1CardCounts::compute_size(heap_rs.size() / HeapWordSize),
1661 G1CardCounts::heap_map_factor());
1662
1663 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1664 G1RegionToSpaceMapper* prev_bitmap_storage =
1665 create_aux_memory_mapper("Prev Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1666 G1RegionToSpaceMapper* next_bitmap_storage =
1667 create_aux_memory_mapper("Next Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1668
1669 _hrm.initialize(heap_storage, prev_bitmap_storage, next_bitmap_storage, bot_storage, cardtable_storage, card_counts_storage);
1670 _card_table->initialize(cardtable_storage);
1671
1672 // Do later initialization work for concurrent refinement.
1673 _hot_card_cache->initialize(card_counts_storage);
1674
1675 // 6843694 - ensure that the maximum region index can fit
1676 // in the remembered set structures.
1677 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1678 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1679
1680 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1681 // start within the first card.
1682 guarantee(heap_rs.base() >= (char*)G1CardTable::card_size, "Java heap must not start within the first card.");
1683 G1FromCardCache::initialize(max_reserved_regions());
1684 // Also create a G1 rem set.
1685 _rem_set = new G1RemSet(this, _card_table, _hot_card_cache);
1686 _rem_set->initialize(max_reserved_regions());
1687
1688 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1689 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1690 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1691 "too many cards per region");
1692
1693 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1694
1695 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1696
1697 {
1698 size_t granularity = HeapRegion::GrainBytes;
1699
1700 _region_attr.initialize(reserved(), granularity);
1701 _humongous_reclaim_candidates.initialize(reserved(), granularity);
1702 }
1703
1704 _workers = new WorkGang("GC Thread", ParallelGCThreads,
1705 true /* are_GC_task_threads */,
1706 false /* are_ConcurrentGC_threads */);
1707 if (_workers == NULL) {
1708 return JNI_ENOMEM;
1709 }
1710 _workers->initialize_workers();
1711
1712 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1713
1714 // Create the G1ConcurrentMark data structure and thread.
1715 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1716 _cm = new G1ConcurrentMark(this, prev_bitmap_storage, next_bitmap_storage);
1717 _cm_thread = _cm->cm_thread();
1718
1719 // Now expand into the initial heap size.
1720 if (!expand(init_byte_size, _workers)) {
1721 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1722 return JNI_ENOMEM;
1723 }
1724
1725 // Perform any initialization actions delegated to the policy.
1726 policy()->init(this, &_collection_set);
1727
1728 jint ecode = initialize_concurrent_refinement();
1729 if (ecode != JNI_OK) {
1730 return ecode;
1731 }
1732
1733 ecode = initialize_service_thread();
1734 if (ecode != JNI_OK) {
1735 return ecode;
1736 }
1737
1738 // Initialize and schedule sampling task on service thread.
1739 _rem_set->initialize_sampling_task(service_thread());
1740
1741 // Create and schedule the periodic gc task on the service thread.
1742 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1743 _service_thread->register_task(_periodic_gc_task);
1744
1745 {
1746 G1DirtyCardQueueSet& dcqs = G1BarrierSet::dirty_card_queue_set();
1747 dcqs.set_process_cards_threshold(concurrent_refine()->yellow_zone());
1748 dcqs.set_max_cards(concurrent_refine()->red_zone());
1749 }
1750
1751 // Here we allocate the dummy HeapRegion that is required by the
1752 // G1AllocRegion class.
1753 HeapRegion* dummy_region = _hrm.get_dummy_region();
1754
1755 // We'll re-use the same region whether the alloc region will
1756 // require BOT updates or not and, if it doesn't, then a non-young
1757 // region will complain that it cannot support allocations without
1758 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1759 dummy_region->set_eden();
1760 // Make sure it's full.
1761 dummy_region->set_top(dummy_region->end());
1762 G1AllocRegion::setup(this, dummy_region);
1763
1764 _allocator->init_mutator_alloc_regions();
1765
1766 // Do create of the monitoring and management support so that
1767 // values in the heap have been properly initialized.
1768 _g1mm = new G1MonitoringSupport(this);
1769
1770 _preserved_marks_set.init(ParallelGCThreads);
1771
1772 _collection_set.initialize(max_reserved_regions());
1773
1774 _regions_failed_evacuation = NEW_C_HEAP_ARRAY(volatile bool, max_regions(), mtGC);
1775
1776 G1InitLogger::print();
1777
1778 SlidingForwarding::initialize(heap_rs.region(), HeapRegion::GrainWords);
1779
1780 return JNI_OK;
1781 }
1782
1783 void G1CollectedHeap::stop() {
1784 // Stop all concurrent threads. We do this to make sure these threads
1785 // do not continue to execute and access resources (e.g. logging)
1786 // that are destroyed during shutdown.
1787 _cr->stop();
1788 _service_thread->stop();
1789 _cm_thread->stop();
1790 }
1791
1792 void G1CollectedHeap::safepoint_synchronize_begin() {
1793 SuspendibleThreadSet::synchronize();
1794 }
1795
1796 void G1CollectedHeap::safepoint_synchronize_end() {
1797 SuspendibleThreadSet::desynchronize();
1798 }
1799
1800 void G1CollectedHeap::post_initialize() {
1801 CollectedHeap::post_initialize();
1802 ref_processing_init();
1803 }
1804
1805 void G1CollectedHeap::ref_processing_init() {
1806 // Reference processing in G1 currently works as follows:
1807 //
1808 // * There are two reference processor instances. One is
1809 // used to record and process discovered references
1810 // during concurrent marking; the other is used to
1811 // record and process references during STW pauses
1812 // (both full and incremental).
1813 // * Both ref processors need to 'span' the entire heap as
1814 // the regions in the collection set may be dotted around.
1815 //
1816 // * For the concurrent marking ref processor:
1817 // * Reference discovery is enabled at concurrent start.
1818 // * Reference discovery is disabled and the discovered
1819 // references processed etc during remarking.
1820 // * Reference discovery is MT (see below).
1821 // * Reference discovery requires a barrier (see below).
1822 // * Reference processing may or may not be MT
1823 // (depending on the value of ParallelRefProcEnabled
1824 // and ParallelGCThreads).
1825 // * A full GC disables reference discovery by the CM
1826 // ref processor and abandons any entries on it's
1827 // discovered lists.
1828 //
1829 // * For the STW processor:
1830 // * Non MT discovery is enabled at the start of a full GC.
1831 // * Processing and enqueueing during a full GC is non-MT.
1832 // * During a full GC, references are processed after marking.
1833 //
1834 // * Discovery (may or may not be MT) is enabled at the start
1835 // of an incremental evacuation pause.
1836 // * References are processed near the end of a STW evacuation pause.
1837 // * For both types of GC:
1838 // * Discovery is atomic - i.e. not concurrent.
1839 // * Reference discovery will not need a barrier.
1840
1841 // Concurrent Mark ref processor
1842 _ref_processor_cm =
1843 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1844 ParallelGCThreads, // degree of mt processing
1845 (ParallelGCThreads > 1) || (ConcGCThreads > 1), // mt discovery
1846 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1847 false, // Reference discovery is not atomic
1848 &_is_alive_closure_cm); // is alive closure
1849
1850 // STW ref processor
1851 _ref_processor_stw =
1852 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1853 ParallelGCThreads, // degree of mt processing
1854 (ParallelGCThreads > 1), // mt discovery
1855 ParallelGCThreads, // degree of mt discovery
1856 true, // Reference discovery is atomic
1857 &_is_alive_closure_stw); // is alive closure
1858 }
1859
1860 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1861 return &_soft_ref_policy;
1862 }
1863
1864 size_t G1CollectedHeap::capacity() const {
1865 return _hrm.length() * HeapRegion::GrainBytes;
1866 }
1867
1868 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1869 return _hrm.total_free_bytes();
1870 }
1871
1872 void G1CollectedHeap::iterate_hcc_closure(G1CardTableEntryClosure* cl, uint worker_id) {
1873 _hot_card_cache->drain(cl, worker_id);
1874 }
1875
1876 // Computes the sum of the storage used by the various regions.
1877 size_t G1CollectedHeap::used() const {
1878 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1879 if (_archive_allocator != NULL) {
1880 result += _archive_allocator->used();
1881 }
1882 return result;
1883 }
1884
1885 size_t G1CollectedHeap::used_unlocked() const {
1886 return _summary_bytes_used;
1887 }
1888
1889 class SumUsedClosure: public HeapRegionClosure {
1890 size_t _used;
1891 public:
1892 SumUsedClosure() : _used(0) {}
1893 bool do_heap_region(HeapRegion* r) {
1894 _used += r->used();
1895 return false;
1896 }
1897 size_t result() { return _used; }
1898 };
1899
1900 size_t G1CollectedHeap::recalculate_used() const {
1901 SumUsedClosure blk;
1902 heap_region_iterate(&blk);
1903 return blk.result();
1904 }
1905
1906 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1907 switch (cause) {
1908 case GCCause::_java_lang_system_gc: return ExplicitGCInvokesConcurrent;
1909 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
1910 case GCCause::_wb_conc_mark: return true;
1911 default : return false;
1912 }
1913 }
1914
1915 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1916 switch (cause) {
1917 case GCCause::_g1_humongous_allocation: return true;
1918 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1919 case GCCause::_wb_breakpoint: return true;
1920 default: return is_user_requested_concurrent_full_gc(cause);
1921 }
1922 }
1923
1924 #ifndef PRODUCT
1925 void G1CollectedHeap::allocate_dummy_regions() {
1926 // Let's fill up most of the region
1927 size_t word_size = HeapRegion::GrainWords - 1024;
1928 // And as a result the region we'll allocate will be humongous.
1929 guarantee(is_humongous(word_size), "sanity");
1930
1931 // _filler_array_max_size is set to humongous object threshold
1932 // but temporarily change it to use CollectedHeap::fill_with_object().
1933 AutoModifyRestore<size_t> temporarily(_filler_array_max_size, word_size);
1934
1935 for (uintx i = 0; i < G1DummyRegionsPerGC; ++i) {
1936 // Let's use the existing mechanism for the allocation
1937 HeapWord* dummy_obj = humongous_obj_allocate(word_size);
1938 if (dummy_obj != NULL) {
1939 MemRegion mr(dummy_obj, word_size);
1940 CollectedHeap::fill_with_object(mr);
1941 } else {
1942 // If we can't allocate once, we probably cannot allocate
1943 // again. Let's get out of the loop.
1944 break;
1945 }
1946 }
1947 }
1948 #endif // !PRODUCT
1949
1950 void G1CollectedHeap::increment_old_marking_cycles_started() {
1951 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1952 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1953 "Wrong marking cycle count (started: %d, completed: %d)",
1954 _old_marking_cycles_started, _old_marking_cycles_completed);
1955
1956 _old_marking_cycles_started++;
1957 }
1958
1959 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1960 bool whole_heap_examined) {
1961 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1962
1963 // We assume that if concurrent == true, then the caller is a
1964 // concurrent thread that was joined the Suspendible Thread
1965 // Set. If there's ever a cheap way to check this, we should add an
1966 // assert here.
1967
1968 // Given that this method is called at the end of a Full GC or of a
1969 // concurrent cycle, and those can be nested (i.e., a Full GC can
1970 // interrupt a concurrent cycle), the number of full collections
1971 // completed should be either one (in the case where there was no
1972 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1973 // behind the number of full collections started.
1974
1975 // This is the case for the inner caller, i.e. a Full GC.
1976 assert(concurrent ||
1977 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1978 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1979 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1980 "is inconsistent with _old_marking_cycles_completed = %u",
1981 _old_marking_cycles_started, _old_marking_cycles_completed);
1982
1983 // This is the case for the outer caller, i.e. the concurrent cycle.
1984 assert(!concurrent ||
1985 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1986 "for outer caller (concurrent cycle): "
1987 "_old_marking_cycles_started = %u "
1988 "is inconsistent with _old_marking_cycles_completed = %u",
1989 _old_marking_cycles_started, _old_marking_cycles_completed);
1990
1991 _old_marking_cycles_completed += 1;
1992 if (whole_heap_examined) {
1993 // Signal that we have completed a visit to all live objects.
1994 record_whole_heap_examined_timestamp();
1995 }
1996
1997 // We need to clear the "in_progress" flag in the CM thread before
1998 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1999 // is set) so that if a waiter requests another System.gc() it doesn't
2000 // incorrectly see that a marking cycle is still in progress.
2001 if (concurrent) {
2002 _cm_thread->set_idle();
2003 }
2004
2005 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
2006 // for a full GC to finish that their wait is over.
2007 ml.notify_all();
2008 }
2009
2010 void G1CollectedHeap::collect(GCCause::Cause cause) {
2011 try_collect(cause);
2012 }
2013
2014 // Return true if (x < y) with allowance for wraparound.
2015 static bool gc_counter_less_than(uint x, uint y) {
2016 return (x - y) > (UINT_MAX/2);
2017 }
2018
2019 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
2020 // Macro so msg printing is format-checked.
2021 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
2022 do { \
2023 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
2024 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
2025 ResourceMark rm; /* For thread name. */ \
2026 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
2027 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
2028 Thread::current()->name(), \
2029 GCCause::to_string(cause)); \
2030 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
2031 } \
2032 } while (0)
2033
2034 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
2035 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
2036
2037 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
2038 uint gc_counter,
2039 uint old_marking_started_before) {
2040 assert_heap_not_locked();
2041 assert(should_do_concurrent_full_gc(cause),
2042 "Non-concurrent cause %s", GCCause::to_string(cause));
2043
2044 for (uint i = 1; true; ++i) {
2045 // Try to schedule concurrent start evacuation pause that will
2046 // start a concurrent cycle.
2047 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
2048 VM_G1TryInitiateConcMark op(gc_counter,
2049 cause,
2050 policy()->max_pause_time_ms());
2051 VMThread::execute(&op);
2052
2053 // Request is trivially finished.
2054 if (cause == GCCause::_g1_periodic_collection) {
2055 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
2056 return op.gc_succeeded();
2057 }
2058
2059 // If VMOp skipped initiating concurrent marking cycle because
2060 // we're terminating, then we're done.
2061 if (op.terminating()) {
2062 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
2063 return false;
2064 }
2065
2066 // Lock to get consistent set of values.
2067 uint old_marking_started_after;
2068 uint old_marking_completed_after;
2069 {
2070 MutexLocker ml(Heap_lock);
2071 // Update gc_counter for retrying VMOp if needed. Captured here to be
2072 // consistent with the values we use below for termination tests. If
2073 // a retry is needed after a possible wait, and another collection
2074 // occurs in the meantime, it will cause our retry to be skipped and
2075 // we'll recheck for termination with updated conditions from that
2076 // more recent collection. That's what we want, rather than having
2077 // our retry possibly perform an unnecessary collection.
2078 gc_counter = total_collections();
2079 old_marking_started_after = _old_marking_cycles_started;
2080 old_marking_completed_after = _old_marking_cycles_completed;
2081 }
2082
2083 if (cause == GCCause::_wb_breakpoint) {
2084 if (op.gc_succeeded()) {
2085 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2086 return true;
2087 }
2088 // When _wb_breakpoint there can't be another cycle or deferred.
2089 assert(!op.cycle_already_in_progress(), "invariant");
2090 assert(!op.whitebox_attached(), "invariant");
2091 // Concurrent cycle attempt might have been cancelled by some other
2092 // collection, so retry. Unlike other cases below, we want to retry
2093 // even if cancelled by a STW full collection, because we really want
2094 // to start a concurrent cycle.
2095 if (old_marking_started_before != old_marking_started_after) {
2096 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
2097 old_marking_started_before = old_marking_started_after;
2098 }
2099 } else if (!GCCause::is_user_requested_gc(cause)) {
2100 // For an "automatic" (not user-requested) collection, we just need to
2101 // ensure that progress is made.
2102 //
2103 // Request is finished if any of
2104 // (1) the VMOp successfully performed a GC,
2105 // (2) a concurrent cycle was already in progress,
2106 // (3) whitebox is controlling concurrent cycles,
2107 // (4) a new cycle was started (by this thread or some other), or
2108 // (5) a Full GC was performed.
2109 // Cases (4) and (5) are detected together by a change to
2110 // _old_marking_cycles_started.
2111 //
2112 // Note that (1) does not imply (4). If we're still in the mixed
2113 // phase of an earlier concurrent collection, the request to make the
2114 // collection a concurrent start won't be honored. If we don't check for
2115 // both conditions we'll spin doing back-to-back collections.
2116 if (op.gc_succeeded() ||
2117 op.cycle_already_in_progress() ||
2118 op.whitebox_attached() ||
2119 (old_marking_started_before != old_marking_started_after)) {
2120 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2121 return true;
2122 }
2123 } else { // User-requested GC.
2124 // For a user-requested collection, we want to ensure that a complete
2125 // full collection has been performed before returning, but without
2126 // waiting for more than needed.
2127
2128 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
2129 // new cycle was started. That's good, because it's not clear what we
2130 // should do otherwise. Trying again just does back to back GCs.
2131 // Can't wait for someone else to start a cycle. And returning fails
2132 // to meet the goal of ensuring a full collection was performed.
2133 assert(!op.gc_succeeded() ||
2134 (old_marking_started_before != old_marking_started_after),
2135 "invariant: succeeded %s, started before %u, started after %u",
2136 BOOL_TO_STR(op.gc_succeeded()),
2137 old_marking_started_before, old_marking_started_after);
2138
2139 // Request is finished if a full collection (concurrent or stw)
2140 // was started after this request and has completed, e.g.
2141 // started_before < completed_after.
2142 if (gc_counter_less_than(old_marking_started_before,
2143 old_marking_completed_after)) {
2144 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2145 return true;
2146 }
2147
2148 if (old_marking_started_after != old_marking_completed_after) {
2149 // If there is an in-progress cycle (possibly started by us), then
2150 // wait for that cycle to complete, e.g.
2151 // while completed_now < started_after.
2152 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2153 MonitorLocker ml(G1OldGCCount_lock);
2154 while (gc_counter_less_than(_old_marking_cycles_completed,
2155 old_marking_started_after)) {
2156 ml.wait();
2157 }
2158 // Request is finished if the collection we just waited for was
2159 // started after this request.
2160 if (old_marking_started_before != old_marking_started_after) {
2161 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2162 return true;
2163 }
2164 }
2165
2166 // If VMOp was successful then it started a new cycle that the above
2167 // wait &etc should have recognized as finishing this request. This
2168 // differs from a non-user-request, where gc_succeeded does not imply
2169 // a new cycle was started.
2170 assert(!op.gc_succeeded(), "invariant");
2171
2172 if (op.cycle_already_in_progress()) {
2173 // If VMOp failed because a cycle was already in progress, it
2174 // is now complete. But it didn't finish this user-requested
2175 // GC, so try again.
2176 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2177 continue;
2178 } else if (op.whitebox_attached()) {
2179 // If WhiteBox wants control, wait for notification of a state
2180 // change in the controller, then try again. Don't wait for
2181 // release of control, since collections may complete while in
2182 // control. Note: This won't recognize a STW full collection
2183 // while waiting; we can't wait on multiple monitors.
2184 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2185 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2186 if (ConcurrentGCBreakpoints::is_controlled()) {
2187 ml.wait();
2188 }
2189 continue;
2190 }
2191 }
2192
2193 // Collection failed and should be retried.
2194 assert(op.transient_failure(), "invariant");
2195
2196 if (GCLocker::is_active_and_needs_gc()) {
2197 // If GCLocker is active, wait until clear before retrying.
2198 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2199 GCLocker::stall_until_clear();
2200 }
2201
2202 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2203 }
2204 }
2205
2206 bool G1CollectedHeap::try_collect(GCCause::Cause cause) {
2207 assert_heap_not_locked();
2208
2209 // Lock to get consistent set of values.
2210 uint gc_count_before;
2211 uint full_gc_count_before;
2212 uint old_marking_started_before;
2213 {
2214 MutexLocker ml(Heap_lock);
2215 gc_count_before = total_collections();
2216 full_gc_count_before = total_full_collections();
2217 old_marking_started_before = _old_marking_cycles_started;
2218 }
2219
2220 if (should_do_concurrent_full_gc(cause)) {
2221 return try_collect_concurrently(cause,
2222 gc_count_before,
2223 old_marking_started_before);
2224 } else if (GCLocker::should_discard(cause, gc_count_before)) {
2225 // Indicate failure to be consistent with VMOp failure due to
2226 // another collection slipping in after our gc_count but before
2227 // our request is processed.
2228 return false;
2229 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2230 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2231
2232 // Schedule a standard evacuation pause. We're setting word_size
2233 // to 0 which means that we are not requesting a post-GC allocation.
2234 VM_G1CollectForAllocation op(0, /* word_size */
2235 gc_count_before,
2236 cause,
2237 policy()->max_pause_time_ms());
2238 VMThread::execute(&op);
2239 return op.gc_succeeded();
2240 } else {
2241 // Schedule a Full GC.
2242 VM_G1CollectFull op(gc_count_before, full_gc_count_before, cause);
2243 VMThread::execute(&op);
2244 return op.gc_succeeded();
2245 }
2246 }
2247
2248 bool G1CollectedHeap::is_in(const void* p) const {
2249 return is_in_reserved(p) && _hrm.is_available(addr_to_region((HeapWord*)p));
2250 }
2251
2252 // Iteration functions.
2253
2254 // Iterates an ObjectClosure over all objects within a HeapRegion.
2255
2256 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2257 ObjectClosure* _cl;
2258 public:
2259 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2260 bool do_heap_region(HeapRegion* r) {
2261 if (!r->is_continues_humongous()) {
2262 r->object_iterate(_cl);
2263 }
2264 return false;
2265 }
2266 };
2267
2268 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2269 IterateObjectClosureRegionClosure blk(cl);
2270 heap_region_iterate(&blk);
2271 }
2272
2273 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2274 private:
2275 G1CollectedHeap* _heap;
2276 HeapRegionClaimer _claimer;
2277
2278 public:
2279 G1ParallelObjectIterator(uint thread_num) :
2280 _heap(G1CollectedHeap::heap()),
2281 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2282
2283 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2284 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2285 }
2286 };
2287
2288 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2289 return new G1ParallelObjectIterator(thread_num);
2290 }
2291
2292 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2293 IterateObjectClosureRegionClosure blk(cl);
2294 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2295 }
2296
2297 void G1CollectedHeap::keep_alive(oop obj) {
2298 G1BarrierSet::enqueue_preloaded(obj);
2299 }
2300
2301 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2302 _hrm.iterate(cl);
2303 }
2304
2305 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2306 HeapRegionClaimer *hrclaimer,
2307 uint worker_id) const {
2308 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2309 }
2310
2311 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2312 HeapRegionClaimer *hrclaimer) const {
2313 _hrm.par_iterate(cl, hrclaimer, 0);
2314 }
2315
2316 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2317 _collection_set.iterate(cl);
2318 }
2319
2320 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2321 _collection_set.par_iterate(cl, hr_claimer, worker_id, workers()->active_workers());
2322 }
2323
2324 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl, HeapRegionClaimer* hr_claimer, uint worker_id) {
2325 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id, workers()->active_workers());
2326 }
2327
2328 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2329 HeapRegion* hr = heap_region_containing(addr);
2330 return hr->block_start(addr);
2331 }
2332
2333 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2334 HeapRegion* hr = heap_region_containing(addr);
2335 return hr->block_is_obj(addr);
2336 }
2337
2338 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2339 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2340 }
2341
2342 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2343 return _eden.length() * HeapRegion::GrainBytes;
2344 }
2345
2346 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2347 // must be equal to the humongous object limit.
2348 size_t G1CollectedHeap::max_tlab_size() const {
2349 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2350 }
2351
2352 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2353 return _allocator->unsafe_max_tlab_alloc();
2354 }
2355
2356 size_t G1CollectedHeap::max_capacity() const {
2357 return max_regions() * HeapRegion::GrainBytes;
2358 }
2359
2360 void G1CollectedHeap::prepare_for_verify() {
2361 _verifier->prepare_for_verify();
2362 }
2363
2364 void G1CollectedHeap::verify(VerifyOption vo) {
2365 _verifier->verify(vo);
2366 }
2367
2368 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2369 return true;
2370 }
2371
2372 bool G1CollectedHeap::is_archived_object(oop object) const {
2373 return object != NULL && heap_region_containing(object)->is_archive();
2374 }
2375
2376 class PrintRegionClosure: public HeapRegionClosure {
2377 outputStream* _st;
2378 public:
2379 PrintRegionClosure(outputStream* st) : _st(st) {}
2380 bool do_heap_region(HeapRegion* r) {
2381 r->print_on(_st);
2382 return false;
2383 }
2384 };
2385
2386 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2387 const HeapRegion* hr,
2388 const VerifyOption vo) const {
2389 switch (vo) {
2390 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj, hr);
2391 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj, hr);
2392 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj, hr);
2393 default: ShouldNotReachHere();
2394 }
2395 return false; // keep some compilers happy
2396 }
2397
2398 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2399 const VerifyOption vo) const {
2400 switch (vo) {
2401 case VerifyOption_G1UsePrevMarking: return is_obj_dead(obj);
2402 case VerifyOption_G1UseNextMarking: return is_obj_ill(obj);
2403 case VerifyOption_G1UseFullMarking: return is_obj_dead_full(obj);
2404 default: ShouldNotReachHere();
2405 }
2406 return false; // keep some compilers happy
2407 }
2408
2409 void G1CollectedHeap::print_heap_regions() const {
2410 LogTarget(Trace, gc, heap, region) lt;
2411 if (lt.is_enabled()) {
2412 LogStream ls(lt);
2413 print_regions_on(&ls);
2414 }
2415 }
2416
2417 void G1CollectedHeap::print_on(outputStream* st) const {
2418 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2419 st->print(" %-20s", "garbage-first heap");
2420 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2421 capacity()/K, heap_used/K);
2422 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2423 p2i(_hrm.reserved().start()),
2424 p2i(_hrm.reserved().end()));
2425 st->cr();
2426 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2427 uint young_regions = young_regions_count();
2428 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2429 (size_t) young_regions * HeapRegion::GrainBytes / K);
2430 uint survivor_regions = survivor_regions_count();
2431 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2432 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2433 st->cr();
2434 if (_numa->is_enabled()) {
2435 uint num_nodes = _numa->num_active_nodes();
2436 st->print(" remaining free region(s) on each NUMA node: ");
2437 const int* node_ids = _numa->node_ids();
2438 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2439 uint num_free_regions = _hrm.num_free_regions(node_index);
2440 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2441 }
2442 st->cr();
2443 }
2444 MetaspaceUtils::print_on(st);
2445 }
2446
2447 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2448 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2449 "HS=humongous(starts), HC=humongous(continues), "
2450 "CS=collection set, F=free, "
2451 "OA=open archive, CA=closed archive, "
2452 "TAMS=top-at-mark-start (previous, next)");
2453 PrintRegionClosure blk(st);
2454 heap_region_iterate(&blk);
2455 }
2456
2457 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2458 print_on(st);
2459
2460 // Print the per-region information.
2461 st->cr();
2462 print_regions_on(st);
2463 }
2464
2465 void G1CollectedHeap::print_on_error(outputStream* st) const {
2466 this->CollectedHeap::print_on_error(st);
2467
2468 if (_cm != NULL) {
2469 st->cr();
2470 _cm->print_on_error(st);
2471 }
2472 }
2473
2474 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2475 workers()->threads_do(tc);
2476 tc->do_thread(_cm_thread);
2477 _cm->threads_do(tc);
2478 _cr->threads_do(tc);
2479 tc->do_thread(_service_thread);
2480 }
2481
2482 void G1CollectedHeap::print_tracing_info() const {
2483 rem_set()->print_summary_info();
2484 concurrent_mark()->print_summary_info();
2485 }
2486
2487 #ifndef PRODUCT
2488 // Helpful for debugging RSet issues.
2489
2490 class PrintRSetsClosure : public HeapRegionClosure {
2491 private:
2492 const char* _msg;
2493 size_t _occupied_sum;
2494
2495 public:
2496 bool do_heap_region(HeapRegion* r) {
2497 HeapRegionRemSet* hrrs = r->rem_set();
2498 size_t occupied = hrrs->occupied();
2499 _occupied_sum += occupied;
2500
2501 tty->print_cr("Printing RSet for region " HR_FORMAT, HR_FORMAT_PARAMS(r));
2502 if (occupied == 0) {
2503 tty->print_cr(" RSet is empty");
2504 } else {
2505 hrrs->print();
2506 }
2507 tty->print_cr("----------");
2508 return false;
2509 }
2510
2511 PrintRSetsClosure(const char* msg) : _msg(msg), _occupied_sum(0) {
2512 tty->cr();
2513 tty->print_cr("========================================");
2514 tty->print_cr("%s", msg);
2515 tty->cr();
2516 }
2517
2518 ~PrintRSetsClosure() {
2519 tty->print_cr("Occupied Sum: " SIZE_FORMAT, _occupied_sum);
2520 tty->print_cr("========================================");
2521 tty->cr();
2522 }
2523 };
2524
2525 void G1CollectedHeap::print_cset_rsets() {
2526 PrintRSetsClosure cl("Printing CSet RSets");
2527 collection_set_iterate_all(&cl);
2528 }
2529
2530 void G1CollectedHeap::print_all_rsets() {
2531 PrintRSetsClosure cl("Printing All RSets");;
2532 heap_region_iterate(&cl);
2533 }
2534 #endif // PRODUCT
2535
2536 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2537 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2538 }
2539
2540 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2541
2542 size_t eden_used_bytes = _eden.used_bytes();
2543 size_t survivor_used_bytes = _survivor.used_bytes();
2544 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2545
2546 size_t eden_capacity_bytes =
2547 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2548
2549 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2550 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes,
2551 eden_capacity_bytes, survivor_used_bytes, num_regions());
2552 }
2553
2554 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2555 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2556 stats->unused(), stats->used(), stats->region_end_waste(),
2557 stats->regions_filled(), stats->direct_allocated(),
2558 stats->failure_used(), stats->failure_waste());
2559 }
2560
2561 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2562 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2563 gc_tracer->report_gc_heap_summary(when, heap_summary);
2564
2565 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2566 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2567 }
2568
2569 void G1CollectedHeap::gc_prologue(bool full) {
2570 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2571
2572 // This summary needs to be printed before incrementing total collections.
2573 rem_set()->print_periodic_summary_info("Before GC RS summary", total_collections());
2574
2575 // Update common counters.
2576 increment_total_collections(full /* full gc */);
2577 if (full || collector_state()->in_concurrent_start_gc()) {
2578 increment_old_marking_cycles_started();
2579 }
2580
2581 // Fill TLAB's and such
2582 {
2583 Ticks start = Ticks::now();
2584 ensure_parsability(true);
2585 Tickspan dt = Ticks::now() - start;
2586 phase_times()->record_prepare_tlab_time_ms(dt.seconds() * MILLIUNITS);
2587 }
2588
2589 if (!full) {
2590 // Flush dirty card queues to qset, so later phases don't need to account
2591 // for partially filled per-thread queues and such. Not needed for full
2592 // collections, which ignore those logs.
2593 Ticks start = Ticks::now();
2594 G1BarrierSet::dirty_card_queue_set().concatenate_logs();
2595 Tickspan dt = Ticks::now() - start;
2596 phase_times()->record_concatenate_dirty_card_logs_time_ms(dt.seconds() * MILLIUNITS);
2597 }
2598 }
2599
2600 void G1CollectedHeap::gc_epilogue(bool full) {
2601 // Update common counters.
2602 if (full) {
2603 // Update the number of full collections that have been completed.
2604 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2605 }
2606
2607 // We are at the end of the GC. Total collections has already been increased.
2608 rem_set()->print_periodic_summary_info("After GC RS summary", total_collections() - 1);
2609
2610 #if COMPILER2_OR_JVMCI
2611 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2612 #endif
2613
2614 double start = os::elapsedTime();
2615 resize_all_tlabs();
2616 phase_times()->record_resize_tlab_time_ms((os::elapsedTime() - start) * 1000.0);
2617
2618 MemoryService::track_memory_usage();
2619 // We have just completed a GC. Update the soft reference
2620 // policy with the new heap occupancy
2621 Universe::heap()->update_capacity_and_used_at_gc();
2622
2623 // Print NUMA statistics.
2624 _numa->print_statistics();
2625
2626 _collection_pause_end = Ticks::now();
2627 }
2628
2629 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2630 return _hrm.uncommit_inactive_regions(region_limit);
2631 }
2632
2633 bool G1CollectedHeap::has_uncommittable_regions() {
2634 return _hrm.has_inactive_regions();
2635 }
2636
2637 void G1CollectedHeap::uncommit_regions_if_necessary() {
2638 if (has_uncommittable_regions()) {
2639 G1UncommitRegionTask::enqueue();
2640 }
2641 }
2642
2643 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2644 LogTarget(Trace, gc, heap, verify) lt;
2645
2646 if (lt.is_enabled()) {
2647 LogStream ls(lt);
2648 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2649 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2650 heap_region_iterate(&cl);
2651 }
2652 }
2653
2654 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2655 uint gc_count_before,
2656 bool* succeeded,
2657 GCCause::Cause gc_cause) {
2658 assert_heap_not_locked_and_not_at_safepoint();
2659 VM_G1CollectForAllocation op(word_size,
2660 gc_count_before,
2661 gc_cause,
2662 policy()->max_pause_time_ms());
2663 VMThread::execute(&op);
2664
2665 HeapWord* result = op.result();
2666 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2667 assert(result == NULL || ret_succeeded,
2668 "the result should be NULL if the VM did not succeed");
2669 *succeeded = ret_succeeded;
2670
2671 assert_heap_not_locked();
2672 return result;
2673 }
2674
2675 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2676 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2677
2678 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2679 if (concurrent_operation_is_full_mark) {
2680 _cm->post_concurrent_mark_start();
2681 _cm_thread->start_full_mark();
2682 } else {
2683 _cm->post_concurrent_undo_start();
2684 _cm_thread->start_undo_mark();
2685 }
2686 CGC_lock->notify();
2687 }
2688
2689 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2690 // We don't nominate objects with many remembered set entries, on
2691 // the assumption that such objects are likely still live.
2692 HeapRegionRemSet* rem_set = r->rem_set();
2693
2694 return G1EagerReclaimHumongousObjectsWithStaleRefs ?
2695 rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold) :
2696 G1EagerReclaimHumongousObjects && rem_set->is_empty();
2697 }
2698
2699 #ifndef PRODUCT
2700 void G1CollectedHeap::verify_region_attr_remset_update() {
2701 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2702 public:
2703 virtual bool do_heap_region(HeapRegion* r) {
2704 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2705 bool const needs_remset_update = g1h->region_attr(r->bottom()).needs_remset_update();
2706 assert(r->rem_set()->is_tracked() == needs_remset_update,
2707 "Region %u remset tracking status (%s) different to region attribute (%s)",
2708 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(needs_remset_update));
2709 return false;
2710 }
2711 } cl;
2712 heap_region_iterate(&cl);
2713 }
2714 #endif
2715
2716 class VerifyRegionRemSetClosure : public HeapRegionClosure {
2717 public:
2718 bool do_heap_region(HeapRegion* hr) {
2719 if (!hr->is_archive() && !hr->is_continues_humongous()) {
2720 hr->verify_rem_set();
2721 }
2722 return false;
2723 }
2724 };
2725
2726 uint G1CollectedHeap::num_task_queues() const {
2727 return _task_queues->size();
2728 }
2729
2730 #if TASKQUEUE_STATS
2731 void G1CollectedHeap::print_taskqueue_stats_hdr(outputStream* const st) {
2732 st->print_raw_cr("GC Task Stats");
2733 st->print_raw("thr "); TaskQueueStats::print_header(1, st); st->cr();
2734 st->print_raw("--- "); TaskQueueStats::print_header(2, st); st->cr();
2735 }
2736
2737 void G1CollectedHeap::print_taskqueue_stats() const {
2738 if (!log_is_enabled(Trace, gc, task, stats)) {
2739 return;
2740 }
2741 Log(gc, task, stats) log;
2742 ResourceMark rm;
2743 LogStream ls(log.trace());
2744 outputStream* st = &ls;
2745
2746 print_taskqueue_stats_hdr(st);
2747
2748 TaskQueueStats totals;
2749 const uint n = num_task_queues();
2750 for (uint i = 0; i < n; ++i) {
2751 st->print("%3u ", i); task_queue(i)->stats.print(st); st->cr();
2752 totals += task_queue(i)->stats;
2753 }
2754 st->print_raw("tot "); totals.print(st); st->cr();
2755
2756 DEBUG_ONLY(totals.verify());
2757 }
2758
2759 void G1CollectedHeap::reset_taskqueue_stats() {
2760 const uint n = num_task_queues();
2761 for (uint i = 0; i < n; ++i) {
2762 task_queue(i)->stats.reset();
2763 }
2764 }
2765 #endif // TASKQUEUE_STATS
2766
2767 void G1CollectedHeap::wait_for_root_region_scanning() {
2768 double scan_wait_start = os::elapsedTime();
2769 // We have to wait until the CM threads finish scanning the
2770 // root regions as it's the only way to ensure that all the
2771 // objects on them have been correctly scanned before we start
2772 // moving them during the GC.
2773 bool waited = _cm->root_regions()->wait_until_scan_finished();
2774 double wait_time_ms = 0.0;
2775 if (waited) {
2776 double scan_wait_end = os::elapsedTime();
2777 wait_time_ms = (scan_wait_end - scan_wait_start) * 1000.0;
2778 }
2779 phase_times()->record_root_region_scan_wait_time(wait_time_ms);
2780 }
2781
2782 class G1PrintCollectionSetClosure : public HeapRegionClosure {
2783 private:
2784 G1HRPrinter* _hr_printer;
2785 public:
2786 G1PrintCollectionSetClosure(G1HRPrinter* hr_printer) : HeapRegionClosure(), _hr_printer(hr_printer) { }
2787
2788 virtual bool do_heap_region(HeapRegion* r) {
2789 _hr_printer->cset(r);
2790 return false;
2791 }
2792 };
2793
2794 void G1CollectedHeap::start_new_collection_set() {
2795 double start = os::elapsedTime();
2796
2797 collection_set()->start_incremental_building();
2798
2799 clear_region_attr();
2800
2801 guarantee(_eden.length() == 0, "eden should have been cleared");
2802 policy()->transfer_survivors_to_cset(survivor());
2803
2804 // We redo the verification but now wrt to the new CSet which
2805 // has just got initialized after the previous CSet was freed.
2806 _cm->verify_no_collection_set_oops();
2807
2808 phase_times()->record_start_new_cset_time_ms((os::elapsedTime() - start) * 1000.0);
2809 }
2810
2811 void G1CollectedHeap::calculate_collection_set(G1EvacuationInfo& evacuation_info, double target_pause_time_ms) {
2812
2813 _collection_set.finalize_initial_collection_set(target_pause_time_ms, &_survivor);
2814 evacuation_info.set_collectionset_regions(collection_set()->region_length() +
2815 collection_set()->optional_region_length());
2816
2817 _cm->verify_no_collection_set_oops();
2818
2819 if (_hr_printer.is_active()) {
2820 G1PrintCollectionSetClosure cl(&_hr_printer);
2821 _collection_set.iterate(&cl);
2822 _collection_set.iterate_optional(&cl);
2823 }
2824 }
2825
2826 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2827 if (collector_state()->in_concurrent_start_gc()) {
2828 return G1HeapVerifier::G1VerifyConcurrentStart;
2829 } else if (collector_state()->in_young_only_phase()) {
2830 return G1HeapVerifier::G1VerifyYoungNormal;
2831 } else {
2832 return G1HeapVerifier::G1VerifyMixed;
2833 }
2834 }
2835
2836 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2837 if (VerifyRememberedSets) {
2838 log_info(gc, verify)("[Verifying RemSets before GC]");
2839 VerifyRegionRemSetClosure v_cl;
2840 heap_region_iterate(&v_cl);
2841 }
2842 _verifier->verify_before_gc(type);
2843 _verifier->check_bitmaps("GC Start");
2844 verify_numa_regions("GC Start");
2845 }
2846
2847 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2848 if (VerifyRememberedSets) {
2849 log_info(gc, verify)("[Verifying RemSets after GC]");
2850 VerifyRegionRemSetClosure v_cl;
2851 heap_region_iterate(&v_cl);
2852 }
2853 _verifier->verify_after_gc(type);
2854 _verifier->check_bitmaps("GC End");
2855 verify_numa_regions("GC End");
2856 }
2857
2858 void G1CollectedHeap::expand_heap_after_young_collection(){
2859 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2860 if (expand_bytes > 0) {
2861 // No need for an ergo logging here,
2862 // expansion_amount() does this when it returns a value > 0.
2863 double expand_ms = 0.0;
2864 if (!expand(expand_bytes, _workers, &expand_ms)) {
2865 // We failed to expand the heap. Cannot do anything about it.
2866 }
2867 phase_times()->record_expand_heap_time(expand_ms);
2868 }
2869 }
2870
2871 void G1CollectedHeap::set_young_gc_name(char* young_gc_name) {
2872 G1GCPauseType pause_type =
2873 // The strings for all Concurrent Start pauses are the same, so the parameter
2874 // does not matter here.
2875 collector_state()->young_gc_pause_type(false /* concurrent_operation_is_full_mark */);
2876 snprintf(young_gc_name,
2877 MaxYoungGCNameLength,
2878 "Pause Young (%s)",
2879 G1GCPauseTypeHelper::to_string(pause_type));
2880 }
2881
2882 bool G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
2883 assert_at_safepoint_on_vm_thread();
2884 guarantee(!is_gc_active(), "collection is not reentrant");
2885
2886 if (GCLocker::check_active_before_gc()) {
2887 return false;
2888 }
2889
2890 do_collection_pause_at_safepoint_helper(target_pause_time_ms);
2891 return true;
2892 }
2893
2894 void G1CollectedHeap::gc_tracer_report_gc_start() {
2895 _gc_timer_stw->register_gc_start();
2896 _gc_tracer_stw->report_gc_start(gc_cause(), _gc_timer_stw->gc_start());
2897 }
2898
2899 void G1CollectedHeap::gc_tracer_report_gc_end(bool concurrent_operation_is_full_mark,
2900 G1EvacuationInfo& evacuation_info) {
2901 _gc_tracer_stw->report_evacuation_info(&evacuation_info);
2902 _gc_tracer_stw->report_tenuring_threshold(_policy->tenuring_threshold());
2903
2904 _gc_timer_stw->register_gc_end();
2905 _gc_tracer_stw->report_gc_end(_gc_timer_stw->gc_end(),
2906 _gc_timer_stw->time_partitions());
2907 }
2908
2909 void G1CollectedHeap::do_collection_pause_at_safepoint_helper(double target_pause_time_ms) {
2910 GCIdMark gc_id_mark;
2911
2912 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2913 ResourceMark rm;
2914
2915 policy()->note_gc_start();
2916
2917 gc_tracer_report_gc_start();
2918
2919 wait_for_root_region_scanning();
2920
2921 print_heap_before_gc();
2922 print_heap_regions();
2923 trace_heap_before_gc(_gc_tracer_stw);
2924
2925 _verifier->verify_region_sets_optional();
2926 _verifier->verify_dirty_young_regions();
2927
2928 // We should not be doing concurrent start unless the concurrent mark thread is running
2929 if (!_cm_thread->should_terminate()) {
2930 // This call will decide whether this pause is a concurrent start
2931 // pause. If it is, in_concurrent_start_gc() will return true
2932 // for the duration of this pause.
2933 policy()->decide_on_conc_mark_initiation();
2934 }
2935
2936 // We do not allow concurrent start to be piggy-backed on a mixed GC.
2937 assert(!collector_state()->in_concurrent_start_gc() ||
2938 collector_state()->in_young_only_phase(), "sanity");
2939 // We also do not allow mixed GCs during marking.
2940 assert(!collector_state()->mark_or_rebuild_in_progress() || collector_state()->in_young_only_phase(), "sanity");
2941
2942 // Record whether this pause may need to trigger a concurrent operation. Later,
2943 // when we signal the G1ConcurrentMarkThread, the collector state has already
2944 // been reset for the next pause.
2945 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2946 bool concurrent_operation_is_full_mark = false;
2947
2948 // Inner scope for scope based logging, timers, and stats collection
2949 {
2950 G1EvacuationInfo evacuation_info;
2951
2952 GCTraceCPUTime tcpu;
2953
2954 char young_gc_name[MaxYoungGCNameLength];
2955 set_young_gc_name(young_gc_name);
2956
2957 GCTraceTime(Info, gc) tm(young_gc_name, NULL, gc_cause(), true);
2958
2959 uint active_workers = WorkerPolicy::calc_active_workers(workers()->total_workers(),
2960 workers()->active_workers(),
2961 Threads::number_of_non_daemon_threads());
2962 active_workers = workers()->update_active_workers(active_workers);
2963 log_info(gc,task)("Using %u workers of %u for evacuation", active_workers, workers()->total_workers());
2964
2965 G1MonitoringScope ms(g1mm(),
2966 false /* full_gc */,
2967 collector_state()->in_mixed_phase() /* all_memory_pools_affected */);
2968
2969 G1HeapTransition heap_transition(this);
2970
2971 {
2972 IsGCActiveMark x;
2973
2974 gc_prologue(false);
2975
2976 G1HeapVerifier::G1VerifyType verify_type = young_collection_verify_type();
2977 verify_before_young_collection(verify_type);
2978
2979 {
2980 // The elapsed time induced by the start time below deliberately elides
2981 // the possible verification above.
2982 double sample_start_time_sec = os::elapsedTime();
2983
2984 // Please see comment in g1CollectedHeap.hpp and
2985 // G1CollectedHeap::ref_processing_init() to see how
2986 // reference processing currently works in G1.
2987 _ref_processor_stw->enable_discovery();
2988
2989 // We want to temporarily turn off discovery by the
2990 // CM ref processor, if necessary, and turn it back on
2991 // on again later if we do. Using a scoped
2992 // NoRefDiscovery object will do this.
2993 NoRefDiscovery no_cm_discovery(_ref_processor_cm);
2994
2995 policy()->record_collection_pause_start(sample_start_time_sec);
2996
2997 // Forget the current allocation region (we might even choose it to be part
2998 // of the collection set!).
2999 _allocator->release_mutator_alloc_regions();
3000
3001 calculate_collection_set(evacuation_info, target_pause_time_ms);
3002
3003 G1RedirtyCardsQueueSet rdcqs(G1BarrierSet::dirty_card_queue_set().allocator());
3004 G1ParScanThreadStateSet per_thread_states(this,
3005 &rdcqs,
3006 workers()->active_workers(),
3007 collection_set()->young_region_length(),
3008 collection_set()->optional_region_length());
3009 pre_evacuate_collection_set(evacuation_info, &per_thread_states);
3010
3011 bool may_do_optional_evacuation = _collection_set.optional_region_length() != 0;
3012 // Actually do the work...
3013 evacuate_initial_collection_set(&per_thread_states, may_do_optional_evacuation);
3014
3015 if (may_do_optional_evacuation) {
3016 evacuate_optional_collection_set(&per_thread_states);
3017 }
3018 post_evacuate_collection_set(evacuation_info, &rdcqs, &per_thread_states);
3019
3020 start_new_collection_set();
3021
3022 _survivor_evac_stats.adjust_desired_plab_sz();
3023 _old_evac_stats.adjust_desired_plab_sz();
3024
3025 allocate_dummy_regions();
3026
3027 _allocator->init_mutator_alloc_regions();
3028
3029 expand_heap_after_young_collection();
3030
3031 // Refine the type of a concurrent mark operation now that we did the
3032 // evacuation, eventually aborting it.
3033 concurrent_operation_is_full_mark = policy()->concurrent_operation_is_full_mark("Revise IHOP");
3034
3035 // Need to report the collection pause now since record_collection_pause_end()
3036 // modifies it to the next state.
3037 _gc_tracer_stw->report_young_gc_pause(collector_state()->young_gc_pause_type(concurrent_operation_is_full_mark));
3038
3039 double sample_end_time_sec = os::elapsedTime();
3040 double pause_time_ms = (sample_end_time_sec - sample_start_time_sec) * MILLIUNITS;
3041 policy()->record_collection_pause_end(pause_time_ms, concurrent_operation_is_full_mark);
3042 }
3043
3044 verify_after_young_collection(verify_type);
3045
3046 gc_epilogue(false);
3047 }
3048
3049 // Print the remainder of the GC log output.
3050 if (evacuation_failed()) {
3051 log_info(gc)("To-space exhausted");
3052 }
3053
3054 policy()->print_phases();
3055 heap_transition.print();
3056
3057 _hrm.verify_optional();
3058 _verifier->verify_region_sets_optional();
3059
3060 TASKQUEUE_STATS_ONLY(print_taskqueue_stats());
3061 TASKQUEUE_STATS_ONLY(reset_taskqueue_stats());
3062
3063 print_heap_after_gc();
3064 print_heap_regions();
3065 trace_heap_after_gc(_gc_tracer_stw);
3066
3067 // We must call G1MonitoringSupport::update_sizes() in the same scoping level
3068 // as an active TraceMemoryManagerStats object (i.e. before the destructor for the
3069 // TraceMemoryManagerStats is called) so that the G1 memory pools are updated
3070 // before any GC notifications are raised.
3071 g1mm()->update_sizes();
3072
3073 gc_tracer_report_gc_end(concurrent_operation_is_full_mark, evacuation_info);
3074 }
3075 // It should now be safe to tell the concurrent mark thread to start
3076 // without its logging output interfering with the logging output
3077 // that came from the pause.
3078
3079 if (should_start_concurrent_mark_operation) {
3080 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
3081 // thread(s) could be running concurrently with us. Make sure that anything
3082 // after this point does not assume that we are the only GC thread running.
3083 // Note: of course, the actual marking work will not start until the safepoint
3084 // itself is released in SuspendibleThreadSet::desynchronize().
3085 start_concurrent_cycle(concurrent_operation_is_full_mark);
3086 ConcurrentGCBreakpoints::notify_idle_to_active();
3087 }
3088 }
3089
3090 void G1CollectedHeap::preserve_mark_during_evac_failure(uint worker_id, oop obj, markWord m) {
3091 _evacuation_failed_info_array[worker_id].register_copy_failure(obj->size());
3092 _preserved_marks_set.get(worker_id)->push_if_necessary(obj, m);
3093 }
3094
3095 bool G1ParEvacuateFollowersClosure::offer_termination() {
3096 EventGCPhaseParallel event;
3097 G1ParScanThreadState* const pss = par_scan_state();
3098 start_term_time();
3099 const bool res = (terminator() == nullptr) ? true : terminator()->offer_termination();
3100 end_term_time();
3101 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(G1GCPhaseTimes::Termination));
3102 return res;
3103 }
3104
3105 void G1ParEvacuateFollowersClosure::do_void() {
3106 EventGCPhaseParallel event;
3107 G1ParScanThreadState* const pss = par_scan_state();
3108 pss->trim_queue();
3109 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3110 do {
3111 EventGCPhaseParallel event;
3112 pss->steal_and_trim_queue(queues());
3113 event.commit(GCId::current(), pss->worker_id(), G1GCPhaseTimes::phase_name(_phase));
3114 } while (!offer_termination());
3115 }
3116
3117 void G1CollectedHeap::complete_cleaning(BoolObjectClosure* is_alive,
3118 bool class_unloading_occurred) {
3119 uint num_workers = workers()->active_workers();
3120 G1ParallelCleaningTask unlink_task(is_alive, num_workers, class_unloading_occurred);
3121 workers()->run_task(&unlink_task);
3122 }
3123
3124 // Weak Reference Processing support
3125
3126 bool G1STWIsAliveClosure::do_object_b(oop p) {
3127 // An object is reachable if it is outside the collection set,
3128 // or is inside and copied.
3129 return !_g1h->is_in_cset(p) || p->is_forwarded();
3130 }
3131
3132 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
3133 assert(obj != NULL, "must not be NULL");
3134 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
3135 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
3136 // may falsely indicate that this is not the case here: however the collection set only
3137 // contains old regions when concurrent mark is not running.
3138 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
3139 }
3140
3141 // Non Copying Keep Alive closure
3142 class G1KeepAliveClosure: public OopClosure {
3143 G1CollectedHeap*_g1h;
3144 public:
3145 G1KeepAliveClosure(G1CollectedHeap* g1h) :_g1h(g1h) {}
3146 void do_oop(narrowOop* p) { guarantee(false, "Not needed"); }
3147 void do_oop(oop* p) {
3148 oop obj = *p;
3149 assert(obj != NULL, "the caller should have filtered out NULL values");
3150
3151 const G1HeapRegionAttr region_attr =_g1h->region_attr(obj);
3152 if (!region_attr.is_in_cset_or_humongous()) {
3153 return;
3154 }
3155 if (region_attr.is_in_cset()) {
3156 assert( obj->is_forwarded(), "invariant" );
3157 *p = obj->forwardee();
3158 } else {
3159 assert(!obj->is_forwarded(), "invariant" );
3160 assert(region_attr.is_humongous(),
3161 "Only allowed G1HeapRegionAttr state is IsHumongous, but is %d", region_attr.type());
3162 _g1h->set_humongous_is_live(obj);
3163 }
3164 }
3165 };
3166
3167 // Copying Keep Alive closure - can be called from both
3168 // serial and parallel code as long as different worker
3169 // threads utilize different G1ParScanThreadState instances
3170 // and different queues.
3171
3172 class G1CopyingKeepAliveClosure: public OopClosure {
3173 G1CollectedHeap* _g1h;
3174 G1ParScanThreadState* _par_scan_state;
3175
3176 public:
3177 G1CopyingKeepAliveClosure(G1CollectedHeap* g1h,
3178 G1ParScanThreadState* pss):
3179 _g1h(g1h),
3180 _par_scan_state(pss)
3181 {}
3182
3183 virtual void do_oop(narrowOop* p) { do_oop_work(p); }
3184 virtual void do_oop( oop* p) { do_oop_work(p); }
3185
3186 template <class T> void do_oop_work(T* p) {
3187 oop obj = RawAccess<>::oop_load(p);
3188
3189 if (_g1h->is_in_cset_or_humongous(obj)) {
3190 // If the referent object has been forwarded (either copied
3191 // to a new location or to itself in the event of an
3192 // evacuation failure) then we need to update the reference
3193 // field and, if both reference and referent are in the G1
3194 // heap, update the RSet for the referent.
3195 //
3196 // If the referent has not been forwarded then we have to keep
3197 // it alive by policy. Therefore we have copy the referent.
3198 //
3199 // When the queue is drained (after each phase of reference processing)
3200 // the object and it's followers will be copied, the reference field set
3201 // to point to the new location, and the RSet updated.
3202 _par_scan_state->push_on_queue(ScannerTask(p));
3203 }
3204 }
3205 };
3206
3207 // Special closure for enqueuing discovered fields: during enqueue the card table
3208 // may not be in shape to properly handle normal barrier calls (e.g. card marks
3209 // in regions that failed evacuation, scribbling of various values by card table
3210 // scan code). Additionally the regular barrier enqueues into the "global"
3211 // DCQS, but during GC we need these to-be-refined entries in the GC local queue
3212 // so that after clearing the card table, the redirty cards phase will properly
3213 // mark all dirty cards to be picked up by refinement.
3214 class G1EnqueueDiscoveredFieldClosure : public EnqueueDiscoveredFieldClosure {
3215 G1CollectedHeap* _g1h;
3216 G1ParScanThreadState* _pss;
3217
3218 public:
3219 G1EnqueueDiscoveredFieldClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) : _g1h(g1h), _pss(pss) { }
3220
3221 virtual void enqueue(HeapWord* discovered_field_addr, oop value) {
3222 assert(_g1h->is_in(discovered_field_addr), PTR_FORMAT " is not in heap ", p2i(discovered_field_addr));
3223 // Store the value first, whatever it is.
3224 RawAccess<>::oop_store(discovered_field_addr, value);
3225 if (value == NULL) {
3226 return;
3227 }
3228 _pss->write_ref_field_post(discovered_field_addr, value);
3229 }
3230 };
3231
3232 // Serial drain queue closure. Called as the 'complete_gc'
3233 // closure for each discovered list in some of the
3234 // reference processing phases.
3235
3236 class G1STWDrainQueueClosure: public VoidClosure {
3237 protected:
3238 G1CollectedHeap* _g1h;
3239 G1ParScanThreadState* _par_scan_state;
3240
3241 G1ParScanThreadState* par_scan_state() { return _par_scan_state; }
3242
3243 public:
3244 G1STWDrainQueueClosure(G1CollectedHeap* g1h, G1ParScanThreadState* pss) :
3245 _g1h(g1h),
3246 _par_scan_state(pss)
3247 { }
3248
3249 void do_void() {
3250 G1ParScanThreadState* const pss = par_scan_state();
3251 pss->trim_queue();
3252 }
3253 };
3254
3255 class G1STWRefProcProxyTask : public RefProcProxyTask {
3256 G1CollectedHeap& _g1h;
3257 G1ParScanThreadStateSet& _pss;
3258 TaskTerminator _terminator;
3259 G1ScannerTasksQueueSet& _task_queues;
3260
3261 public:
3262 G1STWRefProcProxyTask(uint max_workers, G1CollectedHeap& g1h, G1ParScanThreadStateSet& pss, G1ScannerTasksQueueSet& task_queues)
3263 : RefProcProxyTask("G1STWRefProcProxyTask", max_workers),
3264 _g1h(g1h),
3265 _pss(pss),
3266 _terminator(max_workers, &task_queues),
3267 _task_queues(task_queues) {}
3268
3269 void work(uint worker_id) override {
3270 assert(worker_id < _max_workers, "sanity");
3271 uint index = (_tm == RefProcThreadModel::Single) ? 0 : worker_id;
3272 _pss.state_for_worker(index)->set_ref_discoverer(nullptr);
3273 G1STWIsAliveClosure is_alive(&_g1h);
3274 G1CopyingKeepAliveClosure keep_alive(&_g1h, _pss.state_for_worker(index));
3275 G1ParEvacuateFollowersClosure complete_gc(&_g1h, _pss.state_for_worker(index), &_task_queues, _tm == RefProcThreadModel::Single ? nullptr : &_terminator, G1GCPhaseTimes::ObjCopy);
3276 G1EnqueueDiscoveredFieldClosure enqueue(&_g1h, _pss.state_for_worker(index));
3277 _rp_task->rp_work(worker_id, &is_alive, &keep_alive, &enqueue, &complete_gc);
3278 }
3279
3280 void prepare_run_task_hook() override {
3281 _terminator.reset_for_reuse(_queue_count);
3282 }
3283 };
3284
3285 // End of weak reference support closures
3286
3287 void G1CollectedHeap::process_discovered_references(G1ParScanThreadStateSet* per_thread_states) {
3288 double ref_proc_start = os::elapsedTime();
3289
3290 ReferenceProcessor* rp = _ref_processor_stw;
3291 assert(rp->discovery_enabled(), "should have been enabled");
3292
3293 // Use only a single queue for this PSS.
3294 G1ParScanThreadState* pss = per_thread_states->state_for_worker(0);
3295 pss->set_ref_discoverer(NULL);
3296 assert(pss->queue_is_empty(), "pre-condition");
3297
3298 // Setup the soft refs policy...
3299 rp->setup_policy(false);
3300
3301 ReferenceProcessorPhaseTimes& pt = *phase_times()->ref_phase_times();
3302
3303 ReferenceProcessorStats stats;
3304 uint no_of_gc_workers = workers()->active_workers();
3305
3306 // Parallel reference processing
3307 assert(no_of_gc_workers <= rp->max_num_queues(),
3308 "Mismatch between the number of GC workers %u and the maximum number of Reference process queues %u",
3309 no_of_gc_workers, rp->max_num_queues());
3310
3311 rp->set_active_mt_degree(no_of_gc_workers);
3312 G1STWRefProcProxyTask task(rp->max_num_queues(), *this, *per_thread_states, *_task_queues);
3313 stats = rp->process_discovered_references(task, pt);
3314
3315 _gc_tracer_stw->report_gc_reference_stats(stats);
3316
3317 // We have completed copying any necessary live referent objects.
3318 assert(pss->queue_is_empty(), "both queue and overflow should be empty");
3319
3320 make_pending_list_reachable();
3321
3322 assert(!rp->discovery_enabled(), "Postcondition");
3323 rp->verify_no_references_recorded();
3324
3325 double ref_proc_time = os::elapsedTime() - ref_proc_start;
3326 phase_times()->record_ref_proc_time(ref_proc_time * 1000.0);
3327 }
3328
3329 void G1CollectedHeap::make_pending_list_reachable() {
3330 if (collector_state()->in_concurrent_start_gc()) {
3331 oop pll_head = Universe::reference_pending_list();
3332 if (pll_head != NULL) {
3333 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
3334 _cm->mark_in_next_bitmap(0 /* worker_id */, pll_head);
3335 }
3336 }
3337 }
3338
3339 static bool do_humongous_object_logging() {
3340 return log_is_enabled(Debug, gc, humongous);
3341 }
3342
3343 bool G1CollectedHeap::should_do_eager_reclaim() const {
3344 // As eager reclaim logging also gives information about humongous objects in
3345 // the heap in general, always do the eager reclaim pass even without known
3346 // candidates.
3347 return (G1EagerReclaimHumongousObjects &&
3348 (has_humongous_reclaim_candidates() || do_humongous_object_logging()));
3349 }
3350
3351 class G1PrepareEvacuationTask : public AbstractGangTask {
3352 class G1PrepareRegionsClosure : public HeapRegionClosure {
3353 G1CollectedHeap* _g1h;
3354 G1PrepareEvacuationTask* _parent_task;
3355 uint _worker_humongous_total;
3356 uint _worker_humongous_candidates;
3357
3358 bool humongous_region_is_candidate(HeapRegion* region) const {
3359 assert(region->is_starts_humongous(), "Must start a humongous object");
3360
3361 oop obj = cast_to_oop(region->bottom());
3362
3363 // Dead objects cannot be eager reclaim candidates. Due to class
3364 // unloading it is unsafe to query their classes so we return early.
3365 if (_g1h->is_obj_dead(obj, region)) {
3366 return false;
3367 }
3368
3369 // If we do not have a complete remembered set for the region, then we can
3370 // not be sure that we have all references to it.
3371 if (!region->rem_set()->is_complete()) {
3372 return false;
3373 }
3374 // Candidate selection must satisfy the following constraints
3375 // while concurrent marking is in progress:
3376 //
3377 // * In order to maintain SATB invariants, an object must not be
3378 // reclaimed if it was allocated before the start of marking and
3379 // has not had its references scanned. Such an object must have
3380 // its references (including type metadata) scanned to ensure no
3381 // live objects are missed by the marking process. Objects
3382 // allocated after the start of concurrent marking don't need to
3383 // be scanned.
3384 //
3385 // * An object must not be reclaimed if it is on the concurrent
3386 // mark stack. Objects allocated after the start of concurrent
3387 // marking are never pushed on the mark stack.
3388 //
3389 // Nominating only objects allocated after the start of concurrent
3390 // marking is sufficient to meet both constraints. This may miss
3391 // some objects that satisfy the constraints, but the marking data
3392 // structures don't support efficiently performing the needed
3393 // additional tests or scrubbing of the mark stack.
3394 //
3395 // However, we presently only nominate is_typeArray() objects.
3396 // A humongous object containing references induces remembered
3397 // set entries on other regions. In order to reclaim such an
3398 // object, those remembered sets would need to be cleaned up.
3399 //
3400 // We also treat is_typeArray() objects specially, allowing them
3401 // to be reclaimed even if allocated before the start of
3402 // concurrent mark. For this we rely on mark stack insertion to
3403 // exclude is_typeArray() objects, preventing reclaiming an object
3404 // that is in the mark stack. We also rely on the metadata for
3405 // such objects to be built-in and so ensured to be kept live.
3406 // Frequent allocation and drop of large binary blobs is an
3407 // important use case for eager reclaim, and this special handling
3408 // may reduce needed headroom.
3409
3410 return obj->is_typeArray() &&
3411 _g1h->is_potential_eager_reclaim_candidate(region);
3412 }
3413
3414 public:
3415 G1PrepareRegionsClosure(G1CollectedHeap* g1h, G1PrepareEvacuationTask* parent_task) :
3416 _g1h(g1h),
3417 _parent_task(parent_task),
3418 _worker_humongous_total(0),
3419 _worker_humongous_candidates(0) { }
3420
3421 ~G1PrepareRegionsClosure() {
3422 _parent_task->add_humongous_candidates(_worker_humongous_candidates);
3423 _parent_task->add_humongous_total(_worker_humongous_total);
3424 }
3425
3426 virtual bool do_heap_region(HeapRegion* hr) {
3427 // First prepare the region for scanning
3428 _g1h->rem_set()->prepare_region_for_scan(hr);
3429
3430 // Now check if region is a humongous candidate
3431 if (!hr->is_starts_humongous()) {
3432 _g1h->register_region_with_region_attr(hr);
3433 return false;
3434 }
3435
3436 uint index = hr->hrm_index();
3437 if (humongous_region_is_candidate(hr)) {
3438 _g1h->set_humongous_reclaim_candidate(index, true);
3439 _g1h->register_humongous_region_with_region_attr(index);
3440 _worker_humongous_candidates++;
3441 // We will later handle the remembered sets of these regions.
3442 } else {
3443 _g1h->set_humongous_reclaim_candidate(index, false);
3444 _g1h->register_region_with_region_attr(hr);
3445 }
3446 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",
3447 index,
3448 (size_t)cast_to_oop(hr->bottom())->size() * HeapWordSize,
3449 p2i(hr->bottom()),
3450 hr->rem_set()->occupied(),
3451 hr->rem_set()->strong_code_roots_list_length(),
3452 _g1h->concurrent_mark()->next_mark_bitmap()->is_marked(hr->bottom()),
3453 _g1h->is_humongous_reclaim_candidate(index),
3454 cast_to_oop(hr->bottom())->is_typeArray()
3455 );
3456 _worker_humongous_total++;
3457
3458 return false;
3459 }
3460 };
3461
3462 G1CollectedHeap* _g1h;
3463 HeapRegionClaimer _claimer;
3464 volatile uint _humongous_total;
3465 volatile uint _humongous_candidates;
3466 public:
3467 G1PrepareEvacuationTask(G1CollectedHeap* g1h) :
3468 AbstractGangTask("Prepare Evacuation"),
3469 _g1h(g1h),
3470 _claimer(_g1h->workers()->active_workers()),
3471 _humongous_total(0),
3472 _humongous_candidates(0) { }
3473
3474 void work(uint worker_id) {
3475 G1PrepareRegionsClosure cl(_g1h, this);
3476 _g1h->heap_region_par_iterate_from_worker_offset(&cl, &_claimer, worker_id);
3477 }
3478
3479 void add_humongous_candidates(uint candidates) {
3480 Atomic::add(&_humongous_candidates, candidates);
3481 }
3482
3483 void add_humongous_total(uint total) {
3484 Atomic::add(&_humongous_total, total);
3485 }
3486
3487 uint humongous_candidates() {
3488 return _humongous_candidates;
3489 }
3490
3491 uint humongous_total() {
3492 return _humongous_total;
3493 }
3494 };
3495
3496 void G1CollectedHeap::pre_evacuate_collection_set(G1EvacuationInfo& evacuation_info, G1ParScanThreadStateSet* per_thread_states) {
3497 _bytes_used_during_gc = 0;
3498
3499 _expand_heap_after_alloc_failure = true;
3500 Atomic::store(&_num_regions_failed_evacuation, 0u);
3501
3502 memset((void*)_regions_failed_evacuation, false, sizeof(bool) * max_regions());
3503
3504 // Disable the hot card cache.
3505 _hot_card_cache->reset_hot_cache_claimed_index();
3506 _hot_card_cache->set_use_cache(false);
3507
3508 // Initialize the GC alloc regions.
3509 _allocator->init_gc_alloc_regions(evacuation_info);
3510
3511 {
3512 Ticks start = Ticks::now();
3513 rem_set()->prepare_for_scan_heap_roots();
3514 phase_times()->record_prepare_heap_roots_time_ms((Ticks::now() - start).seconds() * 1000.0);
3515 }
3516
3517 {
3518 G1PrepareEvacuationTask g1_prep_task(this);
3519 Tickspan task_time = run_task_timed(&g1_prep_task);
3520
3521 phase_times()->record_register_regions(task_time.seconds() * 1000.0);
3522 _num_humongous_objects = g1_prep_task.humongous_total();
3523 _num_humongous_reclaim_candidates = g1_prep_task.humongous_candidates();
3524 }
3525
3526 assert(_verifier->check_region_attr_table(), "Inconsistency in the region attributes table.");
3527 _preserved_marks_set.assert_empty();
3528
3529 #if COMPILER2_OR_JVMCI
3530 DerivedPointerTable::clear();
3531 #endif
3532
3533 // Concurrent start needs claim bits to keep track of the marked-through CLDs.
3534 if (collector_state()->in_concurrent_start_gc()) {
3535 concurrent_mark()->pre_concurrent_start(gc_cause());
3536
3537 double start_clear_claimed_marks = os::elapsedTime();
3538
3539 ClassLoaderDataGraph::clear_claimed_marks();
3540
3541 double recorded_clear_claimed_marks_time_ms = (os::elapsedTime() - start_clear_claimed_marks) * 1000.0;
3542 phase_times()->record_clear_claimed_marks_time_ms(recorded_clear_claimed_marks_time_ms);
3543 }
3544
3545 // Should G1EvacuationFailureALot be in effect for this GC?
3546 NOT_PRODUCT(set_evacuation_failure_alot_for_current_gc();)
3547 }
3548
3549 class G1EvacuateRegionsBaseTask : public AbstractGangTask {
3550 protected:
3551 G1CollectedHeap* _g1h;
3552 G1ParScanThreadStateSet* _per_thread_states;
3553 G1ScannerTasksQueueSet* _task_queues;
3554 TaskTerminator _terminator;
3555 uint _num_workers;
3556
3557 void evacuate_live_objects(G1ParScanThreadState* pss,
3558 uint worker_id,
3559 G1GCPhaseTimes::GCParPhases objcopy_phase,
3560 G1GCPhaseTimes::GCParPhases termination_phase) {
3561 G1GCPhaseTimes* p = _g1h->phase_times();
3562
3563 Ticks start = Ticks::now();
3564 G1ParEvacuateFollowersClosure cl(_g1h, pss, _task_queues, &_terminator, objcopy_phase);
3565 cl.do_void();
3566
3567 assert(pss->queue_is_empty(), "should be empty");
3568
3569 Tickspan evac_time = (Ticks::now() - start);
3570 p->record_or_add_time_secs(objcopy_phase, worker_id, evac_time.seconds() - cl.term_time());
3571
3572 if (termination_phase == G1GCPhaseTimes::Termination) {
3573 p->record_time_secs(termination_phase, worker_id, cl.term_time());
3574 p->record_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3575 } else {
3576 p->record_or_add_time_secs(termination_phase, worker_id, cl.term_time());
3577 p->record_or_add_thread_work_item(termination_phase, worker_id, cl.term_attempts());
3578 }
3579 assert(pss->trim_ticks().value() == 0,
3580 "Unexpected partial trimming during evacuation value " JLONG_FORMAT,
3581 pss->trim_ticks().value());
3582 }
3583
3584 virtual void start_work(uint worker_id) { }
3585
3586 virtual void end_work(uint worker_id) { }
3587
3588 virtual void scan_roots(G1ParScanThreadState* pss, uint worker_id) = 0;
3589
3590 virtual void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) = 0;
3591
3592 public:
3593 G1EvacuateRegionsBaseTask(const char* name,
3594 G1ParScanThreadStateSet* per_thread_states,
3595 G1ScannerTasksQueueSet* task_queues,
3596 uint num_workers) :
3597 AbstractGangTask(name),
3598 _g1h(G1CollectedHeap::heap()),
3599 _per_thread_states(per_thread_states),
3600 _task_queues(task_queues),
3601 _terminator(num_workers, _task_queues),
3602 _num_workers(num_workers)
3603 { }
3604
3605 void work(uint worker_id) {
3606 start_work(worker_id);
3607
3608 {
3609 ResourceMark rm;
3610
3611 G1ParScanThreadState* pss = _per_thread_states->state_for_worker(worker_id);
3612 pss->set_ref_discoverer(_g1h->ref_processor_stw());
3613
3614 scan_roots(pss, worker_id);
3615 evacuate_live_objects(pss, worker_id);
3616 }
3617
3618 end_work(worker_id);
3619 }
3620 };
3621
3622 class G1EvacuateRegionsTask : public G1EvacuateRegionsBaseTask {
3623 G1RootProcessor* _root_processor;
3624 bool _has_optional_evacuation_work;
3625
3626 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3627 _root_processor->evacuate_roots(pss, worker_id);
3628 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::ObjCopy, _has_optional_evacuation_work);
3629 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::ScanHR, G1GCPhaseTimes::CodeRoots, G1GCPhaseTimes::ObjCopy);
3630 }
3631
3632 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3633 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::ObjCopy, G1GCPhaseTimes::Termination);
3634 }
3635
3636 void start_work(uint worker_id) {
3637 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerStart, worker_id, Ticks::now().seconds());
3638 }
3639
3640 void end_work(uint worker_id) {
3641 _g1h->phase_times()->record_time_secs(G1GCPhaseTimes::GCWorkerEnd, worker_id, Ticks::now().seconds());
3642 }
3643
3644 public:
3645 G1EvacuateRegionsTask(G1CollectedHeap* g1h,
3646 G1ParScanThreadStateSet* per_thread_states,
3647 G1ScannerTasksQueueSet* task_queues,
3648 G1RootProcessor* root_processor,
3649 uint num_workers,
3650 bool has_optional_evacuation_work) :
3651 G1EvacuateRegionsBaseTask("G1 Evacuate Regions", per_thread_states, task_queues, num_workers),
3652 _root_processor(root_processor),
3653 _has_optional_evacuation_work(has_optional_evacuation_work)
3654 { }
3655 };
3656
3657 void G1CollectedHeap::evacuate_initial_collection_set(G1ParScanThreadStateSet* per_thread_states,
3658 bool has_optional_evacuation_work) {
3659 G1GCPhaseTimes* p = phase_times();
3660
3661 {
3662 Ticks start = Ticks::now();
3663 rem_set()->merge_heap_roots(true /* initial_evacuation */);
3664 p->record_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3665 }
3666
3667 Tickspan task_time;
3668 const uint num_workers = workers()->active_workers();
3669
3670 Ticks start_processing = Ticks::now();
3671 {
3672 G1RootProcessor root_processor(this, num_workers);
3673 G1EvacuateRegionsTask g1_par_task(this,
3674 per_thread_states,
3675 _task_queues,
3676 &root_processor,
3677 num_workers,
3678 has_optional_evacuation_work);
3679 task_time = run_task_timed(&g1_par_task);
3680 // Closing the inner scope will execute the destructor for the G1RootProcessor object.
3681 // To extract its code root fixup time we measure total time of this scope and
3682 // subtract from the time the WorkGang task took.
3683 }
3684 Tickspan total_processing = Ticks::now() - start_processing;
3685
3686 p->record_initial_evac_time(task_time.seconds() * 1000.0);
3687 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3688
3689 rem_set()->complete_evac_phase(has_optional_evacuation_work);
3690 }
3691
3692 class G1EvacuateOptionalRegionsTask : public G1EvacuateRegionsBaseTask {
3693
3694 void scan_roots(G1ParScanThreadState* pss, uint worker_id) {
3695 _g1h->rem_set()->scan_heap_roots(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptObjCopy, true /* remember_already_scanned_cards */);
3696 _g1h->rem_set()->scan_collection_set_regions(pss, worker_id, G1GCPhaseTimes::OptScanHR, G1GCPhaseTimes::OptCodeRoots, G1GCPhaseTimes::OptObjCopy);
3697 }
3698
3699 void evacuate_live_objects(G1ParScanThreadState* pss, uint worker_id) {
3700 G1EvacuateRegionsBaseTask::evacuate_live_objects(pss, worker_id, G1GCPhaseTimes::OptObjCopy, G1GCPhaseTimes::OptTermination);
3701 }
3702
3703 public:
3704 G1EvacuateOptionalRegionsTask(G1ParScanThreadStateSet* per_thread_states,
3705 G1ScannerTasksQueueSet* queues,
3706 uint num_workers) :
3707 G1EvacuateRegionsBaseTask("G1 Evacuate Optional Regions", per_thread_states, queues, num_workers) {
3708 }
3709 };
3710
3711 void G1CollectedHeap::evacuate_next_optional_regions(G1ParScanThreadStateSet* per_thread_states) {
3712 class G1MarkScope : public MarkScope { };
3713
3714 Tickspan task_time;
3715
3716 Ticks start_processing = Ticks::now();
3717 {
3718 G1MarkScope code_mark_scope;
3719 G1EvacuateOptionalRegionsTask task(per_thread_states, _task_queues, workers()->active_workers());
3720 task_time = run_task_timed(&task);
3721 // See comment in evacuate_collection_set() for the reason of the scope.
3722 }
3723 Tickspan total_processing = Ticks::now() - start_processing;
3724
3725 G1GCPhaseTimes* p = phase_times();
3726 p->record_or_add_code_root_fixup_time((total_processing - task_time).seconds() * 1000.0);
3727 }
3728
3729 void G1CollectedHeap::evacuate_optional_collection_set(G1ParScanThreadStateSet* per_thread_states) {
3730 const double gc_start_time_ms = phase_times()->cur_collection_start_sec() * 1000.0;
3731
3732 while (!evacuation_failed() && _collection_set.optional_region_length() > 0) {
3733
3734 double time_used_ms = os::elapsedTime() * 1000.0 - gc_start_time_ms;
3735 double time_left_ms = MaxGCPauseMillis - time_used_ms;
3736
3737 if (time_left_ms < 0 ||
3738 !_collection_set.finalize_optional_for_evacuation(time_left_ms * policy()->optional_evacuation_fraction())) {
3739 log_trace(gc, ergo, cset)("Skipping evacuation of %u optional regions, no more regions can be evacuated in %.3fms",
3740 _collection_set.optional_region_length(), time_left_ms);
3741 break;
3742 }
3743
3744 {
3745 Ticks start = Ticks::now();
3746 rem_set()->merge_heap_roots(false /* initial_evacuation */);
3747 phase_times()->record_or_add_optional_merge_heap_roots_time((Ticks::now() - start).seconds() * 1000.0);
3748 }
3749
3750 {
3751 Ticks start = Ticks::now();
3752 evacuate_next_optional_regions(per_thread_states);
3753 phase_times()->record_or_add_optional_evac_time((Ticks::now() - start).seconds() * 1000.0);
3754 }
3755
3756 rem_set()->complete_evac_phase(true /* has_more_than_one_evacuation_phase */);
3757 }
3758
3759 _collection_set.abandon_optional_collection_set(per_thread_states);
3760 }
3761
3762 void G1CollectedHeap::post_evacuate_collection_set(G1EvacuationInfo& evacuation_info,
3763 G1RedirtyCardsQueueSet* rdcqs,
3764 G1ParScanThreadStateSet* per_thread_states) {
3765 G1GCPhaseTimes* p = phase_times();
3766
3767 // Process any discovered reference objects - we have
3768 // to do this _before_ we retire the GC alloc regions
3769 // as we may have to copy some 'reachable' referent
3770 // objects (and their reachable sub-graphs) that were
3771 // not copied during the pause.
3772 process_discovered_references(per_thread_states);
3773
3774 G1STWIsAliveClosure is_alive(this);
3775 G1KeepAliveClosure keep_alive(this);
3776
3777 WeakProcessor::weak_oops_do(workers(), &is_alive, &keep_alive, p->weak_phase_times());
3778
3779 _allocator->release_gc_alloc_regions(evacuation_info);
3780
3781 post_evacuate_cleanup_1(per_thread_states, rdcqs);
3782
3783 post_evacuate_cleanup_2(&_preserved_marks_set, rdcqs, &evacuation_info, per_thread_states->surviving_young_words());
3784
3785 assert_used_and_recalculate_used_equal(this);
3786
3787 rebuild_free_region_list();
3788
3789 record_obj_copy_mem_stats();
3790
3791 evacuation_info.set_collectionset_used_before(collection_set()->bytes_used_before());
3792 evacuation_info.set_bytes_used(_bytes_used_during_gc);
3793
3794 policy()->print_age_table();
3795 }
3796
3797 void G1CollectedHeap::record_obj_copy_mem_stats() {
3798 policy()->old_gen_alloc_tracker()->
3799 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
3800
3801 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
3802 create_g1_evac_summary(&_old_evac_stats));
3803 }
3804
3805 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
3806 assert(!hr->is_free(), "the region should not be free");
3807 assert(!hr->is_empty(), "the region should not be empty");
3808 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
3809
3810 if (G1VerifyBitmaps) {
3811 MemRegion mr(hr->bottom(), hr->end());
3812 concurrent_mark()->clear_range_in_prev_bitmap(mr);
3813 }
3814
3815 // Clear the card counts for this region.
3816 // Note: we only need to do this if the region is not young
3817 // (since we don't refine cards in young regions).
3818 if (!hr->is_young()) {
3819 _hot_card_cache->reset_card_counts(hr);
3820 }
3821
3822 // Reset region metadata to allow reuse.
3823 hr->hr_clear(true /* clear_space */);
3824 _policy->remset_tracker()->update_at_free(hr);
3825
3826 if (free_list != NULL) {
3827 free_list->add_ordered(hr);
3828 }
3829 }
3830
3831 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
3832 FreeRegionList* free_list) {
3833 assert(hr->is_humongous(), "this is only for humongous regions");
3834 hr->clear_humongous();
3835 free_region(hr, free_list);
3836 }
3837
3838 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
3839 const uint archive_regions_removed,
3840 const uint humongous_regions_removed) {
3841 if (old_regions_removed > 0 || archive_regions_removed > 0 || humongous_regions_removed > 0) {
3842 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
3843 _old_set.bulk_remove(old_regions_removed);
3844 _archive_set.bulk_remove(archive_regions_removed);
3845 _humongous_set.bulk_remove(humongous_regions_removed);
3846 }
3847
3848 }
3849
3850 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
3851 assert(list != NULL, "list can't be null");
3852 if (!list->is_empty()) {
3853 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
3854 _hrm.insert_list_into_free_list(list);
3855 }
3856 }
3857
3858 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
3859 decrease_used(bytes);
3860 }
3861
3862 void G1CollectedHeap::post_evacuate_cleanup_1(G1ParScanThreadStateSet* per_thread_states,
3863 G1RedirtyCardsQueueSet* rdcqs) {
3864 Ticks start = Ticks::now();
3865 {
3866 G1PostEvacuateCollectionSetCleanupTask1 cl(per_thread_states, rdcqs);
3867 run_batch_task(&cl);
3868 }
3869 phase_times()->record_post_evacuate_cleanup_task_1_time((Ticks::now() - start).seconds() * 1000.0);
3870 }
3871
3872 void G1CollectedHeap::post_evacuate_cleanup_2(PreservedMarksSet* preserved_marks,
3873 G1RedirtyCardsQueueSet* rdcqs,
3874 G1EvacuationInfo* evacuation_info,
3875 const size_t* surviving_young_words) {
3876 Ticks start = Ticks::now();
3877 {
3878 G1PostEvacuateCollectionSetCleanupTask2 cl(preserved_marks, rdcqs, evacuation_info, surviving_young_words);
3879 run_batch_task(&cl);
3880 }
3881 phase_times()->record_post_evacuate_cleanup_task_2_time((Ticks::now() - start).seconds() * 1000.0);
3882 }
3883
3884 void G1CollectedHeap::clear_eden() {
3885 _eden.clear();
3886 }
3887
3888 void G1CollectedHeap::clear_collection_set() {
3889 collection_set()->clear();
3890 }
3891
3892 void G1CollectedHeap::rebuild_free_region_list() {
3893 Ticks start = Ticks::now();
3894 _hrm.rebuild_free_list(workers());
3895 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
3896 }
3897
3898 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
3899 public:
3900 virtual bool do_heap_region(HeapRegion* r) {
3901 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
3902 G1CollectedHeap::heap()->clear_region_attr(r);
3903 r->clear_young_index_in_cset();
3904 return false;
3905 }
3906 };
3907
3908 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
3909 G1AbandonCollectionSetClosure cl;
3910 collection_set_iterate_all(&cl);
3911
3912 collection_set->clear();
3913 collection_set->stop_incremental_building();
3914 }
3915
3916 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
3917 return _allocator->is_retained_old_region(hr);
3918 }
3919
3920 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
3921 _eden.add(hr);
3922 _policy->set_region_eden(hr);
3923 }
3924
3925 #ifdef ASSERT
3926
3927 class NoYoungRegionsClosure: public HeapRegionClosure {
3928 private:
3929 bool _success;
3930 public:
3931 NoYoungRegionsClosure() : _success(true) { }
3932 bool do_heap_region(HeapRegion* r) {
3933 if (r->is_young()) {
3934 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
3935 p2i(r->bottom()), p2i(r->end()));
3936 _success = false;
3937 }
3938 return false;
3939 }
3940 bool success() { return _success; }
3941 };
3942
3943 bool G1CollectedHeap::check_young_list_empty() {
3944 bool ret = (young_regions_count() == 0);
3945
3946 NoYoungRegionsClosure closure;
3947 heap_region_iterate(&closure);
3948 ret = ret && closure.success();
3949
3950 return ret;
3951 }
3952
3953 #endif // ASSERT
3954
3955 // Remove the given HeapRegion from the appropriate region set.
3956 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
3957 if (hr->is_archive()) {
3958 _archive_set.remove(hr);
3959 } else if (hr->is_humongous()) {
3960 _humongous_set.remove(hr);
3961 } else if (hr->is_old()) {
3962 _old_set.remove(hr);
3963 } else if (hr->is_young()) {
3964 // Note that emptying the eden and survivor lists is postponed and instead
3965 // done as the first step when rebuilding the regions sets again. The reason
3966 // for this is that during a full GC string deduplication needs to know if
3967 // a collected region was young or old when the full GC was initiated.
3968 hr->uninstall_surv_rate_group();
3969 } else {
3970 // We ignore free regions, we'll empty the free list afterwards.
3971 assert(hr->is_free(), "it cannot be another type");
3972 }
3973 }
3974
3975 void G1CollectedHeap::increase_used(size_t bytes) {
3976 _summary_bytes_used += bytes;
3977 }
3978
3979 void G1CollectedHeap::decrease_used(size_t bytes) {
3980 assert(_summary_bytes_used >= bytes,
3981 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
3982 _summary_bytes_used, bytes);
3983 _summary_bytes_used -= bytes;
3984 }
3985
3986 void G1CollectedHeap::set_used(size_t bytes) {
3987 _summary_bytes_used = bytes;
3988 }
3989
3990 class RebuildRegionSetsClosure : public HeapRegionClosure {
3991 private:
3992 bool _free_list_only;
3993
3994 HeapRegionSet* _old_set;
3995 HeapRegionSet* _archive_set;
3996 HeapRegionSet* _humongous_set;
3997
3998 HeapRegionManager* _hrm;
3999
4000 size_t _total_used;
4001
4002 public:
4003 RebuildRegionSetsClosure(bool free_list_only,
4004 HeapRegionSet* old_set,
4005 HeapRegionSet* archive_set,
4006 HeapRegionSet* humongous_set,
4007 HeapRegionManager* hrm) :
4008 _free_list_only(free_list_only), _old_set(old_set), _archive_set(archive_set),
4009 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
4010 assert(_hrm->num_free_regions() == 0, "pre-condition");
4011 if (!free_list_only) {
4012 assert(_old_set->is_empty(), "pre-condition");
4013 assert(_archive_set->is_empty(), "pre-condition");
4014 assert(_humongous_set->is_empty(), "pre-condition");
4015 }
4016 }
4017
4018 bool do_heap_region(HeapRegion* r) {
4019 if (r->is_empty()) {
4020 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
4021 // Add free regions to the free list
4022 r->set_free();
4023 _hrm->insert_into_free_list(r);
4024 } else if (!_free_list_only) {
4025 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
4026
4027 if (r->is_humongous()) {
4028 _humongous_set->add(r);
4029 } else if (r->is_archive()) {
4030 _archive_set->add(r);
4031 } else {
4032 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
4033 // We now move all (non-humongous, non-old, non-archive) regions to old gen,
4034 // and register them as such.
4035 r->move_to_old();
4036 _old_set->add(r);
4037 }
4038 _total_used += r->used();
4039 }
4040
4041 return false;
4042 }
4043
4044 size_t total_used() {
4045 return _total_used;
4046 }
4047 };
4048
4049 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
4050 assert_at_safepoint_on_vm_thread();
4051
4052 if (!free_list_only) {
4053 _eden.clear();
4054 _survivor.clear();
4055 }
4056
4057 RebuildRegionSetsClosure cl(free_list_only,
4058 &_old_set, &_archive_set, &_humongous_set,
4059 &_hrm);
4060 heap_region_iterate(&cl);
4061
4062 if (!free_list_only) {
4063 set_used(cl.total_used());
4064 if (_archive_allocator != NULL) {
4065 _archive_allocator->clear_used();
4066 }
4067 }
4068 assert_used_and_recalculate_used_equal(this);
4069 }
4070
4071 // Methods for the mutator alloc region
4072
4073 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
4074 bool force,
4075 uint node_index) {
4076 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4077 bool should_allocate = policy()->should_allocate_mutator_region();
4078 if (force || should_allocate) {
4079 HeapRegion* new_alloc_region = new_region(word_size,
4080 HeapRegionType::Eden,
4081 false /* do_expand */,
4082 node_index);
4083 if (new_alloc_region != NULL) {
4084 set_region_short_lived_locked(new_alloc_region);
4085 _hr_printer.alloc(new_alloc_region, !should_allocate);
4086 _verifier->check_bitmaps("Mutator Region Allocation", new_alloc_region);
4087 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4088 return new_alloc_region;
4089 }
4090 }
4091 return NULL;
4092 }
4093
4094 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
4095 size_t allocated_bytes) {
4096 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
4097 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
4098
4099 collection_set()->add_eden_region(alloc_region);
4100 increase_used(allocated_bytes);
4101 _eden.add_used_bytes(allocated_bytes);
4102 _hr_printer.retire(alloc_region);
4103
4104 // We update the eden sizes here, when the region is retired,
4105 // instead of when it's allocated, since this is the point that its
4106 // used space has been recorded in _summary_bytes_used.
4107 g1mm()->update_eden_size();
4108 }
4109
4110 // Methods for the GC alloc regions
4111
4112 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
4113 if (dest.is_old()) {
4114 return true;
4115 } else {
4116 return survivor_regions_count() < policy()->max_survivor_regions();
4117 }
4118 }
4119
4120 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
4121 assert(FreeList_lock->owned_by_self(), "pre-condition");
4122
4123 if (!has_more_regions(dest)) {
4124 return NULL;
4125 }
4126
4127 HeapRegionType type;
4128 if (dest.is_young()) {
4129 type = HeapRegionType::Survivor;
4130 } else {
4131 type = HeapRegionType::Old;
4132 }
4133
4134 HeapRegion* new_alloc_region = new_region(word_size,
4135 type,
4136 true /* do_expand */,
4137 node_index);
4138
4139 if (new_alloc_region != NULL) {
4140 if (type.is_survivor()) {
4141 new_alloc_region->set_survivor();
4142 _survivor.add(new_alloc_region);
4143 _verifier->check_bitmaps("Survivor Region Allocation", new_alloc_region);
4144 } else {
4145 new_alloc_region->set_old();
4146 _verifier->check_bitmaps("Old Region Allocation", new_alloc_region);
4147 }
4148 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
4149 register_region_with_region_attr(new_alloc_region);
4150 _hr_printer.alloc(new_alloc_region);
4151 return new_alloc_region;
4152 }
4153 return NULL;
4154 }
4155
4156 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
4157 size_t allocated_bytes,
4158 G1HeapRegionAttr dest) {
4159 _bytes_used_during_gc += allocated_bytes;
4160 if (dest.is_old()) {
4161 old_set_add(alloc_region);
4162 } else {
4163 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
4164 _survivor.add_used_bytes(allocated_bytes);
4165 }
4166
4167 bool const during_im = collector_state()->in_concurrent_start_gc();
4168 if (during_im && allocated_bytes > 0) {
4169 _cm->root_regions()->add(alloc_region->next_top_at_mark_start(), alloc_region->top());
4170 }
4171 _hr_printer.retire(alloc_region);
4172 }
4173
4174 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
4175 bool expanded = false;
4176 uint index = _hrm.find_highest_free(&expanded);
4177
4178 if (index != G1_NO_HRM_INDEX) {
4179 if (expanded) {
4180 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
4181 HeapRegion::GrainWords * HeapWordSize);
4182 }
4183 return _hrm.allocate_free_regions_starting_at(index, 1);
4184 }
4185 return NULL;
4186 }
4187
4188 // Optimized nmethod scanning
4189
4190 class RegisterNMethodOopClosure: public OopClosure {
4191 G1CollectedHeap* _g1h;
4192 nmethod* _nm;
4193
4194 template <class T> void do_oop_work(T* p) {
4195 T heap_oop = RawAccess<>::oop_load(p);
4196 if (!CompressedOops::is_null(heap_oop)) {
4197 oop obj = CompressedOops::decode_not_null(heap_oop);
4198 HeapRegion* hr = _g1h->heap_region_containing(obj);
4199 assert(!hr->is_continues_humongous(),
4200 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4201 " starting at " HR_FORMAT,
4202 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4203
4204 // HeapRegion::add_strong_code_root_locked() avoids adding duplicate entries.
4205 hr->add_strong_code_root_locked(_nm);
4206 }
4207 }
4208
4209 public:
4210 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4211 _g1h(g1h), _nm(nm) {}
4212
4213 void do_oop(oop* p) { do_oop_work(p); }
4214 void do_oop(narrowOop* p) { do_oop_work(p); }
4215 };
4216
4217 class UnregisterNMethodOopClosure: public OopClosure {
4218 G1CollectedHeap* _g1h;
4219 nmethod* _nm;
4220
4221 template <class T> void do_oop_work(T* p) {
4222 T heap_oop = RawAccess<>::oop_load(p);
4223 if (!CompressedOops::is_null(heap_oop)) {
4224 oop obj = CompressedOops::decode_not_null(heap_oop);
4225 HeapRegion* hr = _g1h->heap_region_containing(obj);
4226 assert(!hr->is_continues_humongous(),
4227 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
4228 " starting at " HR_FORMAT,
4229 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
4230
4231 hr->remove_strong_code_root(_nm);
4232 }
4233 }
4234
4235 public:
4236 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
4237 _g1h(g1h), _nm(nm) {}
4238
4239 void do_oop(oop* p) { do_oop_work(p); }
4240 void do_oop(narrowOop* p) { do_oop_work(p); }
4241 };
4242
4243 void G1CollectedHeap::register_nmethod(nmethod* nm) {
4244 guarantee(nm != NULL, "sanity");
4245 RegisterNMethodOopClosure reg_cl(this, nm);
4246 nm->oops_do(®_cl);
4247 }
4248
4249 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
4250 guarantee(nm != NULL, "sanity");
4251 UnregisterNMethodOopClosure reg_cl(this, nm);
4252 nm->oops_do(®_cl, true);
4253 }
4254
4255 void G1CollectedHeap::update_used_after_gc() {
4256 if (evacuation_failed()) {
4257 // Reset the G1EvacuationFailureALot counters and flags
4258 NOT_PRODUCT(reset_evacuation_should_fail();)
4259
4260 set_used(recalculate_used());
4261
4262 if (_archive_allocator != NULL) {
4263 _archive_allocator->clear_used();
4264 }
4265 for (uint i = 0; i < ParallelGCThreads; i++) {
4266 if (_evacuation_failed_info_array[i].has_failed()) {
4267 _gc_tracer_stw->report_evacuation_failed(_evacuation_failed_info_array[i]);
4268 }
4269 }
4270 } else {
4271 // The "used" of the the collection set have already been subtracted
4272 // when they were freed. Add in the bytes used.
4273 increase_used(_bytes_used_during_gc);
4274 }
4275 }
4276
4277 void G1CollectedHeap::reset_hot_card_cache() {
4278 _hot_card_cache->reset_hot_cache();
4279 _hot_card_cache->set_use_cache(true);
4280 }
4281
4282 void G1CollectedHeap::purge_code_root_memory() {
4283 G1CodeRootSet::purge();
4284 }
4285
4286 class RebuildStrongCodeRootClosure: public CodeBlobClosure {
4287 G1CollectedHeap* _g1h;
4288
4289 public:
4290 RebuildStrongCodeRootClosure(G1CollectedHeap* g1h) :
4291 _g1h(g1h) {}
4292
4293 void do_code_blob(CodeBlob* cb) {
4294 nmethod* nm = (cb != NULL) ? cb->as_nmethod_or_null() : NULL;
4295 if (nm == NULL) {
4296 return;
4297 }
4298
4299 _g1h->register_nmethod(nm);
4300 }
4301 };
4302
4303 void G1CollectedHeap::rebuild_strong_code_roots() {
4304 RebuildStrongCodeRootClosure blob_cl(this);
4305 CodeCache::blobs_do(&blob_cl);
4306 }
4307
4308 void G1CollectedHeap::initialize_serviceability() {
4309 _g1mm->initialize_serviceability();
4310 }
4311
4312 MemoryUsage G1CollectedHeap::memory_usage() {
4313 return _g1mm->memory_usage();
4314 }
4315
4316 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
4317 return _g1mm->memory_managers();
4318 }
4319
4320 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
4321 return _g1mm->memory_pools();
4322 }