1 /*
2 * Copyright (c) 2001, 2023, 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.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "compiler/oopMap.hpp"
32 #include "gc/g1/g1Allocator.inline.hpp"
33 #include "gc/g1/g1Arguments.hpp"
34 #include "gc/g1/g1BarrierSet.hpp"
35 #include "gc/g1/g1BatchedTask.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectionSetCandidates.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1ConcurrentRefine.hpp"
41 #include "gc/g1/g1ConcurrentRefineThread.hpp"
42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
43 #include "gc/g1/g1DirtyCardQueue.hpp"
44 #include "gc/g1/g1EvacStats.inline.hpp"
45 #include "gc/g1/g1FullCollector.hpp"
46 #include "gc/g1/g1GCCounters.hpp"
47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
48 #include "gc/g1/g1GCPhaseTimes.hpp"
49 #include "gc/g1/g1GCPauseType.hpp"
50 #include "gc/g1/g1HeapSizingPolicy.hpp"
51 #include "gc/g1/g1HeapTransition.hpp"
52 #include "gc/g1/g1HeapVerifier.hpp"
53 #include "gc/g1/g1InitLogger.hpp"
54 #include "gc/g1/g1MemoryPool.hpp"
55 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.hpp"
56 #include "gc/g1/g1OopClosures.inline.hpp"
57 #include "gc/g1/g1ParallelCleaning.hpp"
58 #include "gc/g1/g1ParScanThreadState.inline.hpp"
59 #include "gc/g1/g1PeriodicGCTask.hpp"
60 #include "gc/g1/g1Policy.hpp"
61 #include "gc/g1/g1RedirtyCardsQueue.hpp"
62 #include "gc/g1/g1RegionToSpaceMapper.hpp"
63 #include "gc/g1/g1RemSet.hpp"
64 #include "gc/g1/g1RootClosures.hpp"
65 #include "gc/g1/g1RootProcessor.hpp"
66 #include "gc/g1/g1SATBMarkQueueSet.hpp"
67 #include "gc/g1/g1ServiceThread.hpp"
68 #include "gc/g1/g1ThreadLocalData.hpp"
69 #include "gc/g1/g1Trace.hpp"
70 #include "gc/g1/g1UncommitRegionTask.hpp"
71 #include "gc/g1/g1VMOperations.hpp"
72 #include "gc/g1/g1YoungCollector.hpp"
73 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp"
74 #include "gc/g1/heapRegion.inline.hpp"
75 #include "gc/g1/heapRegionRemSet.inline.hpp"
76 #include "gc/g1/heapRegionSet.inline.hpp"
77 #include "gc/shared/concurrentGCBreakpoints.hpp"
78 #include "gc/shared/gcBehaviours.hpp"
79 #include "gc/shared/gcHeapSummary.hpp"
80 #include "gc/shared/gcId.hpp"
81 #include "gc/shared/gcLocker.inline.hpp"
82 #include "gc/shared/gcTimer.hpp"
83 #include "gc/shared/gcTraceTime.inline.hpp"
84 #include "gc/shared/generationSpec.hpp"
85 #include "gc/shared/isGCActiveMark.hpp"
86 #include "gc/shared/locationPrinter.inline.hpp"
87 #include "gc/shared/oopStorageParState.hpp"
88 #include "gc/shared/preservedMarks.inline.hpp"
89 #include "gc/shared/referenceProcessor.inline.hpp"
90 #include "gc/shared/suspendibleThreadSet.hpp"
91 #include "gc/shared/taskqueue.inline.hpp"
92 #include "gc/shared/taskTerminator.hpp"
93 #include "gc/shared/tlab_globals.hpp"
94 #include "gc/shared/workerPolicy.hpp"
95 #include "gc/shared/weakProcessor.inline.hpp"
96 #include "logging/log.hpp"
97 #include "memory/allocation.hpp"
98 #include "memory/heapInspection.hpp"
99 #include "memory/iterator.hpp"
100 #include "memory/metaspaceUtils.hpp"
101 #include "memory/resourceArea.hpp"
102 #include "memory/universe.hpp"
103 #include "oops/access.inline.hpp"
104 #include "oops/compressedOops.inline.hpp"
105 #include "oops/oop.inline.hpp"
106 #include "runtime/atomic.hpp"
107 #include "runtime/handles.inline.hpp"
108 #include "runtime/init.hpp"
109 #include "runtime/java.hpp"
110 #include "runtime/orderAccess.hpp"
111 #include "runtime/threadSMR.hpp"
112 #include "runtime/vmThread.hpp"
113 #include "utilities/align.hpp"
114 #include "utilities/autoRestore.hpp"
115 #include "utilities/bitMap.inline.hpp"
116 #include "utilities/globalDefinitions.hpp"
117 #include "utilities/stack.inline.hpp"
118
119 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
120
121 // INVARIANTS/NOTES
122 //
123 // All allocation activity covered by the G1CollectedHeap interface is
124 // serialized by acquiring the HeapLock. This happens in mem_allocate
125 // and allocate_new_tlab, which are the "entry" points to the
126 // allocation code from the rest of the JVM. (Note that this does not
127 // apply to TLAB allocation, which is not part of this interface: it
128 // is done by clients of this interface.)
129
130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
132 }
133
134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
135 // The from card cache is not the memory that is actually committed. So we cannot
136 // take advantage of the zero_filled parameter.
137 reset_from_card_cache(start_idx, num_regions);
138 }
139
140 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
141 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
142 cl->set_max_workers(num_workers);
143 workers()->run_task(cl, num_workers);
144 }
145
146 uint G1CollectedHeap::get_chunks_per_region() {
147 uint log_region_size = HeapRegion::LogOfHRGrainBytes;
148 // Limit the expected input values to current known possible values of the
149 // (log) region size. Adjust as necessary after testing if changing the permissible
150 // values for region size.
151 assert(log_region_size >= 20 && log_region_size <= 29,
152 "expected value in [20,29], but got %u", log_region_size);
153 return 1u << (log_region_size / 2 - 4);
154 }
155
156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
157 MemRegion mr) {
158 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
159 }
160
161 // Private methods.
162
163 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
164 HeapRegionType type,
165 bool do_expand,
166 uint node_index) {
167 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
168 "the only time we use this to allocate a humongous region is "
169 "when we are allocating a single humongous region");
170
171 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
172
173 if (res == nullptr && do_expand) {
174 // Currently, only attempts to allocate GC alloc regions set
175 // do_expand to true. So, we should only reach here during a
176 // safepoint.
177 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
178
179 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
180 word_size * HeapWordSize);
181
182 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
183 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
184 word_size * HeapWordSize);
185 if (expand_single_region(node_index)) {
186 // Given that expand_single_region() succeeded in expanding the heap, and we
187 // always expand the heap by an amount aligned to the heap
188 // region size, the free list should in theory not be empty.
189 // In either case allocate_free_region() will check for null.
190 res = _hrm.allocate_free_region(type, node_index);
191 }
192 }
193 return res;
194 }
195
196 void G1CollectedHeap::set_humongous_metadata(HeapRegion* first_hr,
197 uint num_regions,
198 size_t word_size,
199 bool update_remsets) {
200 // Calculate the new top of the humongous object.
201 HeapWord* obj_top = first_hr->bottom() + word_size;
202 // The word size sum of all the regions used
203 size_t word_size_sum = num_regions * HeapRegion::GrainWords;
204 assert(word_size <= word_size_sum, "sanity");
205
206 // How many words memory we "waste" which cannot hold a filler object.
207 size_t words_not_fillable = 0;
208
209 // Pad out the unused tail of the last region with filler
210 // objects, for improved usage accounting.
211
212 // How many words can we use for filler objects.
213 size_t words_fillable = word_size_sum - word_size;
214
215 if (words_fillable >= G1CollectedHeap::min_fill_size()) {
216 G1CollectedHeap::fill_with_objects(obj_top, words_fillable);
217 } else {
218 // We have space to fill, but we cannot fit an object there.
219 words_not_fillable = words_fillable;
220 words_fillable = 0;
221 }
222
223 // We will set up the first region as "starts humongous". This
224 // will also update the BOT covering all the regions to reflect
225 // that there is a single object that starts at the bottom of the
226 // first region.
227 first_hr->hr_clear(false /* clear_space */);
228 first_hr->set_starts_humongous(obj_top, words_fillable);
229
230 if (update_remsets) {
231 _policy->remset_tracker()->update_at_allocate(first_hr);
232 }
233
234 // Indices of first and last regions in the series.
235 uint first = first_hr->hrm_index();
236 uint last = first + num_regions - 1;
237
238 HeapRegion* hr = nullptr;
239 for (uint i = first + 1; i <= last; ++i) {
240 hr = region_at(i);
241 hr->hr_clear(false /* clear_space */);
242 hr->set_continues_humongous(first_hr);
243 if (update_remsets) {
244 _policy->remset_tracker()->update_at_allocate(hr);
245 }
246 }
247
248 // Up to this point no concurrent thread would have been able to
249 // do any scanning on any region in this series. All the top
250 // fields still point to bottom, so the intersection between
251 // [bottom,top] and [card_start,card_end] will be empty. Before we
252 // update the top fields, we'll do a storestore to make sure that
253 // no thread sees the update to top before the zeroing of the
254 // object header and the BOT initialization.
255 OrderAccess::storestore();
256
257 // Now, we will update the top fields of the "continues humongous"
258 // regions except the last one.
259 for (uint i = first; i < last; ++i) {
260 hr = region_at(i);
261 hr->set_top(hr->end());
262 }
263
264 hr = region_at(last);
265 // If we cannot fit a filler object, we must set top to the end
266 // of the humongous object, otherwise we cannot iterate the heap
267 // and the BOT will not be complete.
268 hr->set_top(hr->end() - words_not_fillable);
269
270 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
271 "obj_top should be in last region");
272
273 assert(words_not_fillable == 0 ||
274 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
275 "Miscalculation in humongous allocation");
276 }
277
278 HeapWord*
279 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
280 uint num_regions,
281 size_t word_size) {
282 assert(first_hr != nullptr, "pre-condition");
283 assert(is_humongous(word_size), "word_size should be humongous");
284 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
285
286 // Index of last region in the series.
287 uint first = first_hr->hrm_index();
288 uint last = first + num_regions - 1;
289
290 // We need to initialize the region(s) we just discovered. This is
291 // a bit tricky given that it can happen concurrently with
292 // refinement threads refining cards on these regions and
293 // potentially wanting to refine the BOT as they are scanning
294 // those cards (this can happen shortly after a cleanup; see CR
295 // 6991377). So we have to set up the region(s) carefully and in
296 // a specific order.
297
298 // The passed in hr will be the "starts humongous" region. The header
299 // of the new object will be placed at the bottom of this region.
300 HeapWord* new_obj = first_hr->bottom();
301
302 // First, we need to zero the header of the space that we will be
303 // allocating. When we update top further down, some refinement
304 // threads might try to scan the region. By zeroing the header we
305 // ensure that any thread that will try to scan the region will
306 // come across the zero klass word and bail out.
307 //
308 // NOTE: It would not have been correct to have used
309 // CollectedHeap::fill_with_object() and make the space look like
310 // an int array. The thread that is doing the allocation will
311 // later update the object header to a potentially different array
312 // type and, for a very short period of time, the klass and length
313 // fields will be inconsistent. This could cause a refinement
314 // thread to calculate the object size incorrectly.
315 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
316
317 // Next, update the metadata for the regions.
318 set_humongous_metadata(first_hr, num_regions, word_size, true);
319
320 HeapRegion* last_hr = region_at(last);
321 size_t used = byte_size(first_hr->bottom(), last_hr->top());
322
323 increase_used(used);
324
325 for (uint i = first; i <= last; ++i) {
326 HeapRegion *hr = region_at(i);
327 _humongous_set.add(hr);
328 _hr_printer.alloc(hr);
329 }
330
331 return new_obj;
332 }
333
334 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
335 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
336 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
337 }
338
339 // If could fit into free regions w/o expansion, try.
340 // Otherwise, if can expand, do so.
341 // Otherwise, if using ex regions might help, try with ex given back.
342 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
343 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
344
345 _verifier->verify_region_sets_optional();
346
347 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
348
349 // Policy: First try to allocate a humongous object in the free list.
350 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
351 if (humongous_start == nullptr) {
352 // Policy: We could not find enough regions for the humongous object in the
353 // free list. Look through the heap to find a mix of free and uncommitted regions.
354 // If so, expand the heap and allocate the humongous object.
355 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
356 if (humongous_start != nullptr) {
357 // We managed to find a region by expanding the heap.
358 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
359 word_size * HeapWordSize);
360 policy()->record_new_heap_size(num_regions());
361 } else {
362 // Policy: Potentially trigger a defragmentation GC.
363 }
364 }
365
366 HeapWord* result = nullptr;
367 if (humongous_start != nullptr) {
368 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
369 assert(result != nullptr, "it should always return a valid result");
370
371 // A successful humongous object allocation changes the used space
372 // information of the old generation so we need to recalculate the
373 // sizes and update the jstat counters here.
374 monitoring_support()->update_sizes();
375 }
376
377 _verifier->verify_region_sets_optional();
378
379 return result;
380 }
381
382 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
383 size_t requested_size,
384 size_t* actual_size) {
385 assert_heap_not_locked_and_not_at_safepoint();
386 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
387
388 return attempt_allocation(min_size, requested_size, actual_size);
389 }
390
391 HeapWord*
392 G1CollectedHeap::mem_allocate(size_t word_size,
393 bool* gc_overhead_limit_was_exceeded) {
394 assert_heap_not_locked_and_not_at_safepoint();
395
396 if (is_humongous(word_size)) {
397 return attempt_allocation_humongous(word_size);
398 }
399 size_t dummy = 0;
400 return attempt_allocation(word_size, word_size, &dummy);
401 }
402
403 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
404 ResourceMark rm; // For retrieving the thread names in log messages.
405
406 // Make sure you read the note in attempt_allocation_humongous().
407
408 assert_heap_not_locked_and_not_at_safepoint();
409 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
410 "be called for humongous allocation requests");
411
412 // We should only get here after the first-level allocation attempt
413 // (attempt_allocation()) failed to allocate.
414
415 // We will loop until a) we manage to successfully perform the
416 // allocation or b) we successfully schedule a collection which
417 // fails to perform the allocation. b) is the only case when we'll
418 // return null.
419 HeapWord* result = nullptr;
420 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
421 bool should_try_gc;
422 uint gc_count_before;
423
424 {
425 MutexLocker x(Heap_lock);
426
427 // Now that we have the lock, we first retry the allocation in case another
428 // thread changed the region while we were waiting to acquire the lock.
429 result = _allocator->attempt_allocation_locked(word_size);
430 if (result != nullptr) {
431 return result;
432 }
433
434 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
435 // This is different to when only GCLocker::needs_gc() is set: try to avoid
436 // waiting because the GCLocker is active to not wait too long.
437 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
438 // No need for an ergo message here, can_expand_young_list() does this when
439 // it returns true.
440 result = _allocator->attempt_allocation_force(word_size);
441 if (result != nullptr) {
442 return result;
443 }
444 }
445
446 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
447 // the GCLocker initiated GC has been performed and then retry. This includes
448 // the case when the GC Locker is not active but has not been performed.
449 should_try_gc = !GCLocker::needs_gc();
450 // Read the GC count while still holding the Heap_lock.
451 gc_count_before = total_collections();
452 }
453
454 if (should_try_gc) {
455 bool succeeded;
456 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause);
457 if (result != nullptr) {
458 assert(succeeded, "only way to get back a non-null result");
459 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
460 Thread::current()->name(), p2i(result));
461 return result;
462 }
463
464 if (succeeded) {
465 // We successfully scheduled a collection which failed to allocate. No
466 // point in trying to allocate further. We'll just return null.
467 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
468 SIZE_FORMAT " words", Thread::current()->name(), word_size);
469 return nullptr;
470 }
471 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
472 Thread::current()->name(), word_size);
473 } else {
474 // Failed to schedule a collection.
475 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
476 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
477 SIZE_FORMAT " words", Thread::current()->name(), word_size);
478 return nullptr;
479 }
480 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
481 // The GCLocker is either active or the GCLocker initiated
482 // GC has not yet been performed. Stall until it is and
483 // then retry the allocation.
484 GCLocker::stall_until_clear();
485 gclocker_retry_count += 1;
486 }
487
488 // We can reach here if we were unsuccessful in scheduling a
489 // collection (because another thread beat us to it) or if we were
490 // stalled due to the GC locker. In either can we should retry the
491 // allocation attempt in case another thread successfully
492 // performed a collection and reclaimed enough space. We do the
493 // first attempt (without holding the Heap_lock) here and the
494 // follow-on attempt will be at the start of the next loop
495 // iteration (after taking the Heap_lock).
496 size_t dummy = 0;
497 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
498 if (result != nullptr) {
499 return result;
500 }
501
502 // Give a warning if we seem to be looping forever.
503 if ((QueuedAllocationWarningCount > 0) &&
504 (try_count % QueuedAllocationWarningCount == 0)) {
505 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
506 Thread::current()->name(), try_count, word_size);
507 }
508 }
509
510 ShouldNotReachHere();
511 return nullptr;
512 }
513
514 template <typename Func>
515 void G1CollectedHeap::iterate_regions_in_range(MemRegion range, const Func& func) {
516 // Mark each G1 region touched by the range as old, add it to
517 // the old set, and set top.
518 HeapRegion* curr_region = _hrm.addr_to_region(range.start());
519 HeapRegion* end_region = _hrm.addr_to_region(range.last());
520
521 while (curr_region != nullptr) {
522 bool is_last = curr_region == end_region;
523 HeapRegion* next_region = is_last ? nullptr : _hrm.next_region_in_heap(curr_region);
524
525 func(curr_region, is_last);
526
527 curr_region = next_region;
528 }
529 }
530
531 HeapWord* G1CollectedHeap::alloc_archive_region(size_t word_size, HeapWord* preferred_addr) {
532 assert(!is_init_completed(), "Expect to be called at JVM init time");
533 MutexLocker x(Heap_lock);
534
535 MemRegion reserved = _hrm.reserved();
536
537 if (reserved.word_size() <= word_size) {
538 log_info(gc, heap)("Unable to allocate regions as archive heap is too large; size requested = " SIZE_FORMAT
539 " bytes, heap = " SIZE_FORMAT " bytes", word_size, reserved.word_size());
540 return nullptr;
541 }
542
543 // Temporarily disable pretouching of heap pages. This interface is used
544 // when mmap'ing archived heap data in, so pre-touching is wasted.
545 FlagSetting fs(AlwaysPreTouch, false);
546
547 size_t commits = 0;
548 // Attempt to allocate towards the end of the heap.
549 HeapWord* start_addr = reserved.end() - align_up(word_size, HeapRegion::GrainWords);
550 MemRegion range = MemRegion(start_addr, word_size);
551 HeapWord* last_address = range.last();
552 if (!_hrm.allocate_containing_regions(range, &commits, workers())) {
553 return nullptr;
554 }
555 increase_used(word_size * HeapWordSize);
556 if (commits != 0) {
557 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
558 HeapRegion::GrainWords * HeapWordSize * commits);
559 }
560
561 // Mark each G1 region touched by the range as old, add it to
562 // the old set, and set top.
563 auto set_region_to_old = [&] (HeapRegion* r, bool is_last) {
564 assert(r->is_empty(), "Region already in use (%u)", r->hrm_index());
565
566 HeapWord* top = is_last ? last_address + 1 : r->end();
567 r->set_top(top);
568
569 r->set_old();
570 _hr_printer.alloc(r);
571 _old_set.add(r);
572 };
573
574 iterate_regions_in_range(range, set_region_to_old);
575 return start_addr;
576 }
577
578 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion range) {
579 assert(!is_init_completed(), "Expect to be called at JVM init time");
580
581 iterate_regions_in_range(range,
582 [&] (HeapRegion* r, bool is_last) {
583 r->update_bot();
584 });
585 }
586
587 void G1CollectedHeap::dealloc_archive_regions(MemRegion range) {
588 assert(!is_init_completed(), "Expect to be called at JVM init time");
589 MemRegion reserved = _hrm.reserved();
590 size_t size_used = 0;
591 uint shrink_count = 0;
592
593 // Free the G1 regions that are within the specified range.
594 MutexLocker x(Heap_lock);
595 HeapWord* start_address = range.start();
596 HeapWord* last_address = range.last();
597
598 assert(reserved.contains(start_address) && reserved.contains(last_address),
599 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
600 p2i(start_address), p2i(last_address));
601 size_used += range.byte_size();
602
603 // Free, empty and uncommit regions with CDS archive content.
604 auto dealloc_archive_region = [&] (HeapRegion* r, bool is_last) {
605 guarantee(r->is_old(), "Expected old region at index %u", r->hrm_index());
606 _old_set.remove(r);
607 r->set_free();
608 r->set_top(r->bottom());
609 _hrm.shrink_at(r->hrm_index(), 1);
610 shrink_count++;
611 };
612
613 iterate_regions_in_range(range, dealloc_archive_region);
614
615 if (shrink_count != 0) {
616 log_debug(gc, ergo, heap)("Attempt heap shrinking (CDS archive regions). Total size: " SIZE_FORMAT "B",
617 HeapRegion::GrainWords * HeapWordSize * shrink_count);
618 // Explicit uncommit.
619 uncommit_regions(shrink_count);
620 }
621 decrease_used(size_used);
622 }
623
624 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
625 size_t desired_word_size,
626 size_t* actual_word_size) {
627 assert_heap_not_locked_and_not_at_safepoint();
628 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
629 "be called for humongous allocation requests");
630
631 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
632
633 if (result == nullptr) {
634 *actual_word_size = desired_word_size;
635 result = attempt_allocation_slow(desired_word_size);
636 }
637
638 assert_heap_not_locked();
639 if (result != nullptr) {
640 assert(*actual_word_size != 0, "Actual size must have been set here");
641 dirty_young_block(result, *actual_word_size);
642 } else {
643 *actual_word_size = 0;
644 }
645
646 return result;
647 }
648
649 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
650 ResourceMark rm; // For retrieving the thread names in log messages.
651
652 // The structure of this method has a lot of similarities to
653 // attempt_allocation_slow(). The reason these two were not merged
654 // into a single one is that such a method would require several "if
655 // allocation is not humongous do this, otherwise do that"
656 // conditional paths which would obscure its flow. In fact, an early
657 // version of this code did use a unified method which was harder to
658 // follow and, as a result, it had subtle bugs that were hard to
659 // track down. So keeping these two methods separate allows each to
660 // be more readable. It will be good to keep these two in sync as
661 // much as possible.
662
663 assert_heap_not_locked_and_not_at_safepoint();
664 assert(is_humongous(word_size), "attempt_allocation_humongous() "
665 "should only be called for humongous allocations");
666
667 // Humongous objects can exhaust the heap quickly, so we should check if we
668 // need to start a marking cycle at each humongous object allocation. We do
669 // the check before we do the actual allocation. The reason for doing it
670 // before the allocation is that we avoid having to keep track of the newly
671 // allocated memory while we do a GC.
672 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
673 word_size)) {
674 collect(GCCause::_g1_humongous_allocation);
675 }
676
677 // We will loop until a) we manage to successfully perform the
678 // allocation or b) we successfully schedule a collection which
679 // fails to perform the allocation. b) is the only case when we'll
680 // return null.
681 HeapWord* result = nullptr;
682 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
683 bool should_try_gc;
684 uint gc_count_before;
685
686
687 {
688 MutexLocker x(Heap_lock);
689
690 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
691 // Given that humongous objects are not allocated in young
692 // regions, we'll first try to do the allocation without doing a
693 // collection hoping that there's enough space in the heap.
694 result = humongous_obj_allocate(word_size);
695 if (result != nullptr) {
696 policy()->old_gen_alloc_tracker()->
697 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
698 return result;
699 }
700
701 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
702 // the GCLocker initiated GC has been performed and then retry. This includes
703 // the case when the GC Locker is not active but has not been performed.
704 should_try_gc = !GCLocker::needs_gc();
705 // Read the GC count while still holding the Heap_lock.
706 gc_count_before = total_collections();
707 }
708
709 if (should_try_gc) {
710 bool succeeded;
711 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
712 if (result != nullptr) {
713 assert(succeeded, "only way to get back a non-null result");
714 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
715 Thread::current()->name(), p2i(result));
716 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
717 policy()->old_gen_alloc_tracker()->
718 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
719 return result;
720 }
721
722 if (succeeded) {
723 // We successfully scheduled a collection which failed to allocate. No
724 // point in trying to allocate further. We'll just return null.
725 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
726 SIZE_FORMAT " words", Thread::current()->name(), word_size);
727 return nullptr;
728 }
729 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
730 Thread::current()->name(), word_size);
731 } else {
732 // Failed to schedule a collection.
733 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
734 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
735 SIZE_FORMAT " words", Thread::current()->name(), word_size);
736 return nullptr;
737 }
738 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
739 // The GCLocker is either active or the GCLocker initiated
740 // GC has not yet been performed. Stall until it is and
741 // then retry the allocation.
742 GCLocker::stall_until_clear();
743 gclocker_retry_count += 1;
744 }
745
746
747 // We can reach here if we were unsuccessful in scheduling a
748 // collection (because another thread beat us to it) or if we were
749 // stalled due to the GC locker. In either can we should retry the
750 // allocation attempt in case another thread successfully
751 // performed a collection and reclaimed enough space.
752 // Humongous object allocation always needs a lock, so we wait for the retry
753 // in the next iteration of the loop, unlike for the regular iteration case.
754 // Give a warning if we seem to be looping forever.
755
756 if ((QueuedAllocationWarningCount > 0) &&
757 (try_count % QueuedAllocationWarningCount == 0)) {
758 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
759 Thread::current()->name(), try_count, word_size);
760 }
761 }
762
763 ShouldNotReachHere();
764 return nullptr;
765 }
766
767 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
768 bool expect_null_mutator_alloc_region) {
769 assert_at_safepoint_on_vm_thread();
770 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
771 "the current alloc region was unexpectedly found to be non-null");
772
773 if (!is_humongous(word_size)) {
774 return _allocator->attempt_allocation_locked(word_size);
775 } else {
776 HeapWord* result = humongous_obj_allocate(word_size);
777 if (result != nullptr && policy()->need_to_start_conc_mark("STW humongous allocation")) {
778 collector_state()->set_initiate_conc_mark_if_possible(true);
779 }
780 return result;
781 }
782
783 ShouldNotReachHere();
784 }
785
786 class PostCompactionPrinterClosure: public HeapRegionClosure {
787 private:
788 G1HRPrinter* _hr_printer;
789 public:
790 bool do_heap_region(HeapRegion* hr) {
791 assert(!hr->is_young(), "not expecting to find young regions");
792 _hr_printer->post_compaction(hr);
793 return false;
794 }
795
796 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
797 : _hr_printer(hr_printer) { }
798 };
799
800 void G1CollectedHeap::print_heap_after_full_collection() {
801 // Post collection region logging.
802 // We should do this after we potentially resize the heap so
803 // that all the COMMIT / UNCOMMIT events are generated before
804 // the compaction events.
805 if (_hr_printer.is_active()) {
806 PostCompactionPrinterClosure cl(hr_printer());
807 heap_region_iterate(&cl);
808 }
809 }
810
811 bool G1CollectedHeap::abort_concurrent_cycle() {
812 // Disable discovery and empty the discovered lists
813 // for the CM ref processor.
814 _ref_processor_cm->disable_discovery();
815 _ref_processor_cm->abandon_partial_discovery();
816 _ref_processor_cm->verify_no_references_recorded();
817
818 // Abandon current iterations of concurrent marking and concurrent
819 // refinement, if any are in progress.
820 return concurrent_mark()->concurrent_cycle_abort();
821 }
822
823 void G1CollectedHeap::prepare_heap_for_full_collection() {
824 // Make sure we'll choose a new allocation region afterwards.
825 _allocator->release_mutator_alloc_regions();
826 _allocator->abandon_gc_alloc_regions();
827
828 // We may have added regions to the current incremental collection
829 // set between the last GC or pause and now. We need to clear the
830 // incremental collection set and then start rebuilding it afresh
831 // after this full GC.
832 abandon_collection_set(collection_set());
833
834 _hrm.remove_all_free_regions();
835 }
836
837 void G1CollectedHeap::verify_before_full_collection() {
838 assert_used_and_recalculate_used_equal(this);
839 if (!VerifyBeforeGC) {
840 return;
841 }
842 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
843 return;
844 }
845 _verifier->verify_region_sets_optional();
846 _verifier->verify_before_gc();
847 _verifier->verify_bitmap_clear(true /* above_tams_only */);
848 }
849
850 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
851 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
852 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
853 DEBUG_ONLY(MetaspaceUtils::verify();)
854
855 // Prepare heap for normal collections.
856 assert(num_free_regions() == 0, "we should not have added any free regions");
857 rebuild_region_sets(false /* free_list_only */);
858 abort_refinement();
859 resize_heap_if_necessary();
860 uncommit_regions_if_necessary();
861
862 // Rebuild the code root lists for each region
863 rebuild_code_roots();
864
865 start_new_collection_set();
866 _allocator->init_mutator_alloc_regions();
867
868 // Post collection state updates.
869 MetaspaceGC::compute_new_size();
870 }
871
872 void G1CollectedHeap::abort_refinement() {
873 // Discard all remembered set updates and reset refinement statistics.
874 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
875 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
876 "DCQS should be empty");
877 concurrent_refine()->get_and_reset_refinement_stats();
878 }
879
880 void G1CollectedHeap::verify_after_full_collection() {
881 if (!VerifyAfterGC) {
882 return;
883 }
884 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
885 return;
886 }
887 _hrm.verify_optional();
888 _verifier->verify_region_sets_optional();
889 _verifier->verify_after_gc();
890 _verifier->verify_bitmap_clear(false /* above_tams_only */);
891
892 // At this point there should be no regions in the
893 // entire heap tagged as young.
894 assert(check_young_list_empty(), "young list should be empty at this point");
895
896 // Note: since we've just done a full GC, concurrent
897 // marking is no longer active. Therefore we need not
898 // re-enable reference discovery for the CM ref processor.
899 // That will be done at the start of the next marking cycle.
900 // We also know that the STW processor should no longer
901 // discover any new references.
902 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
903 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
904 _ref_processor_stw->verify_no_references_recorded();
905 _ref_processor_cm->verify_no_references_recorded();
906 }
907
908 bool G1CollectedHeap::do_full_collection(bool clear_all_soft_refs,
909 bool do_maximal_compaction) {
910 assert_at_safepoint_on_vm_thread();
911
912 if (GCLocker::check_active_before_gc()) {
913 // Full GC was not completed.
914 return false;
915 }
916
917 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
918 soft_ref_policy()->should_clear_all_soft_refs();
919
920 G1FullGCMark gc_mark;
921 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause(), true);
922 G1FullCollector collector(this, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
923
924 collector.prepare_collection();
925 collector.collect();
926 collector.complete_collection();
927
928 // Full collection was successfully completed.
929 return true;
930 }
931
932 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
933 // Currently, there is no facility in the do_full_collection(bool) API to notify
934 // the caller that the collection did not succeed (e.g., because it was locked
935 // out by the GC locker). So, right now, we'll ignore the return value.
936
937 do_full_collection(clear_all_soft_refs,
938 false /* do_maximal_compaction */);
939 }
940
941 bool G1CollectedHeap::upgrade_to_full_collection() {
942 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
943 log_info(gc, ergo)("Attempting full compaction clearing soft references");
944 bool success = do_full_collection(true /* clear_all_soft_refs */,
945 false /* do_maximal_compaction */);
946 // do_full_collection only fails if blocked by GC locker and that can't
947 // be the case here since we only call this when already completed one gc.
948 assert(success, "invariant");
949 return success;
950 }
951
952 void G1CollectedHeap::resize_heap_if_necessary() {
953 assert_at_safepoint_on_vm_thread();
954
955 bool should_expand;
956 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
957
958 if (resize_amount == 0) {
959 return;
960 } else if (should_expand) {
961 expand(resize_amount, _workers);
962 } else {
963 shrink(resize_amount);
964 }
965 }
966
967 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
968 bool do_gc,
969 bool maximal_compaction,
970 bool expect_null_mutator_alloc_region,
971 bool* gc_succeeded) {
972 *gc_succeeded = true;
973 // Let's attempt the allocation first.
974 HeapWord* result =
975 attempt_allocation_at_safepoint(word_size,
976 expect_null_mutator_alloc_region);
977 if (result != nullptr) {
978 return result;
979 }
980
981 // In a G1 heap, we're supposed to keep allocation from failing by
982 // incremental pauses. Therefore, at least for now, we'll favor
983 // expansion over collection. (This might change in the future if we can
984 // do something smarter than full collection to satisfy a failed alloc.)
985 result = expand_and_allocate(word_size);
986 if (result != nullptr) {
987 return result;
988 }
989
990 if (do_gc) {
991 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
992 // Expansion didn't work, we'll try to do a Full GC.
993 // If maximal_compaction is set we clear all soft references and don't
994 // allow any dead wood to be left on the heap.
995 if (maximal_compaction) {
996 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
997 } else {
998 log_info(gc, ergo)("Attempting full compaction");
999 }
1000 *gc_succeeded = do_full_collection(maximal_compaction /* clear_all_soft_refs */ ,
1001 maximal_compaction /* do_maximal_compaction */);
1002 }
1003
1004 return nullptr;
1005 }
1006
1007 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1008 bool* succeeded) {
1009 assert_at_safepoint_on_vm_thread();
1010
1011 // Attempts to allocate followed by Full GC.
1012 HeapWord* result =
1013 satisfy_failed_allocation_helper(word_size,
1014 true, /* do_gc */
1015 false, /* maximum_collection */
1016 false, /* expect_null_mutator_alloc_region */
1017 succeeded);
1018
1019 if (result != nullptr || !*succeeded) {
1020 return result;
1021 }
1022
1023 // Attempts to allocate followed by Full GC that will collect all soft references.
1024 result = satisfy_failed_allocation_helper(word_size,
1025 true, /* do_gc */
1026 true, /* maximum_collection */
1027 true, /* expect_null_mutator_alloc_region */
1028 succeeded);
1029
1030 if (result != nullptr || !*succeeded) {
1031 return result;
1032 }
1033
1034 // Attempts to allocate, no GC
1035 result = satisfy_failed_allocation_helper(word_size,
1036 false, /* do_gc */
1037 false, /* maximum_collection */
1038 true, /* expect_null_mutator_alloc_region */
1039 succeeded);
1040
1041 if (result != nullptr) {
1042 return result;
1043 }
1044
1045 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1046 "Flag should have been handled and cleared prior to this point");
1047
1048 // What else? We might try synchronous finalization later. If the total
1049 // space available is large enough for the allocation, then a more
1050 // complete compaction phase than we've tried so far might be
1051 // appropriate.
1052 return nullptr;
1053 }
1054
1055 // Attempting to expand the heap sufficiently
1056 // to support an allocation of the given "word_size". If
1057 // successful, perform the allocation and return the address of the
1058 // allocated block, or else null.
1059
1060 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1061 assert_at_safepoint_on_vm_thread();
1062
1063 _verifier->verify_region_sets_optional();
1064
1065 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1066 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1067 word_size * HeapWordSize);
1068
1069
1070 if (expand(expand_bytes, _workers)) {
1071 _hrm.verify_optional();
1072 _verifier->verify_region_sets_optional();
1073 return attempt_allocation_at_safepoint(word_size,
1074 false /* expect_null_mutator_alloc_region */);
1075 }
1076 return nullptr;
1077 }
1078
1079 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1080 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1081 aligned_expand_bytes = align_up(aligned_expand_bytes,
1082 HeapRegion::GrainBytes);
1083
1084 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1085 expand_bytes, aligned_expand_bytes);
1086
1087 if (is_maximal_no_gc()) {
1088 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1089 return false;
1090 }
1091
1092 double expand_heap_start_time_sec = os::elapsedTime();
1093 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1094 assert(regions_to_expand > 0, "Must expand by at least one region");
1095
1096 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1097 if (expand_time_ms != nullptr) {
1098 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1099 }
1100
1101 assert(expanded_by > 0, "must have failed during commit.");
1102
1103 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1104 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1105 policy()->record_new_heap_size(num_regions());
1106
1107 return true;
1108 }
1109
1110 bool G1CollectedHeap::expand_single_region(uint node_index) {
1111 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1112
1113 if (expanded_by == 0) {
1114 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1115 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1116 return false;
1117 }
1118
1119 policy()->record_new_heap_size(num_regions());
1120 return true;
1121 }
1122
1123 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1124 size_t aligned_shrink_bytes =
1125 ReservedSpace::page_align_size_down(shrink_bytes);
1126 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1127 HeapRegion::GrainBytes);
1128 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1129
1130 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1131 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1132
1133 log_debug(gc, ergo, heap)("Shrink the heap. requested shrinking amount: " SIZE_FORMAT "B aligned shrinking amount: " SIZE_FORMAT "B actual amount shrunk: " SIZE_FORMAT "B",
1134 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1135 if (num_regions_removed > 0) {
1136 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1137 policy()->record_new_heap_size(num_regions());
1138 } else {
1139 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1140 }
1141 }
1142
1143 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1144 _verifier->verify_region_sets_optional();
1145
1146 // We should only reach here at the end of a Full GC or during Remark which
1147 // means we should not not be holding to any GC alloc regions. The method
1148 // below will make sure of that and do any remaining clean up.
1149 _allocator->abandon_gc_alloc_regions();
1150
1151 // Instead of tearing down / rebuilding the free lists here, we
1152 // could instead use the remove_all_pending() method on free_list to
1153 // remove only the ones that we need to remove.
1154 _hrm.remove_all_free_regions();
1155 shrink_helper(shrink_bytes);
1156 rebuild_region_sets(true /* free_list_only */);
1157
1158 _hrm.verify_optional();
1159 _verifier->verify_region_sets_optional();
1160 }
1161
1162 class OldRegionSetChecker : public HeapRegionSetChecker {
1163 public:
1164 void check_mt_safety() {
1165 // Master Old Set MT safety protocol:
1166 // (a) If we're at a safepoint, operations on the master old set
1167 // should be invoked:
1168 // - by the VM thread (which will serialize them), or
1169 // - by the GC workers while holding the FreeList_lock, if we're
1170 // at a safepoint for an evacuation pause (this lock is taken
1171 // anyway when an GC alloc region is retired so that a new one
1172 // is allocated from the free list), or
1173 // - by the GC workers while holding the OldSets_lock, if we're at a
1174 // safepoint for a cleanup pause.
1175 // (b) If we're not at a safepoint, operations on the master old set
1176 // should be invoked while holding the Heap_lock.
1177
1178 if (SafepointSynchronize::is_at_safepoint()) {
1179 guarantee(Thread::current()->is_VM_thread() ||
1180 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1181 "master old set MT safety protocol at a safepoint");
1182 } else {
1183 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1184 }
1185 }
1186 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1187 const char* get_description() { return "Old Regions"; }
1188 };
1189
1190 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1191 public:
1192 void check_mt_safety() {
1193 // Humongous Set MT safety protocol:
1194 // (a) If we're at a safepoint, operations on the master humongous
1195 // set should be invoked by either the VM thread (which will
1196 // serialize them) or by the GC workers while holding the
1197 // OldSets_lock.
1198 // (b) If we're not at a safepoint, operations on the master
1199 // humongous set should be invoked while holding the Heap_lock.
1200
1201 if (SafepointSynchronize::is_at_safepoint()) {
1202 guarantee(Thread::current()->is_VM_thread() ||
1203 OldSets_lock->owned_by_self(),
1204 "master humongous set MT safety protocol at a safepoint");
1205 } else {
1206 guarantee(Heap_lock->owned_by_self(),
1207 "master humongous set MT safety protocol outside a safepoint");
1208 }
1209 }
1210 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1211 const char* get_description() { return "Humongous Regions"; }
1212 };
1213
1214 G1CollectedHeap::G1CollectedHeap() :
1215 CollectedHeap(),
1216 _service_thread(nullptr),
1217 _periodic_gc_task(nullptr),
1218 _free_arena_memory_task(nullptr),
1219 _workers(nullptr),
1220 _card_table(nullptr),
1221 _collection_pause_end(Ticks::now()),
1222 _soft_ref_policy(),
1223 _old_set("Old Region Set", new OldRegionSetChecker()),
1224 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1225 _bot(nullptr),
1226 _listener(),
1227 _numa(G1NUMA::create()),
1228 _hrm(),
1229 _allocator(nullptr),
1230 _evac_failure_injector(),
1231 _verifier(nullptr),
1232 _summary_bytes_used(0),
1233 _bytes_used_during_gc(0),
1234 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1235 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1236 _monitoring_support(nullptr),
1237 _num_humongous_objects(0),
1238 _num_humongous_reclaim_candidates(0),
1239 _hr_printer(),
1240 _collector_state(),
1241 _old_marking_cycles_started(0),
1242 _old_marking_cycles_completed(0),
1243 _eden(),
1244 _survivor(),
1245 _gc_timer_stw(new STWGCTimer()),
1246 _gc_tracer_stw(new G1NewTracer()),
1247 _policy(new G1Policy(_gc_timer_stw)),
1248 _heap_sizing_policy(nullptr),
1249 _collection_set(this, _policy),
1250 _rem_set(nullptr),
1251 _card_set_config(),
1252 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1253 _cm(nullptr),
1254 _cm_thread(nullptr),
1255 _cr(nullptr),
1256 _task_queues(nullptr),
1257 _ref_processor_stw(nullptr),
1258 _is_alive_closure_stw(this),
1259 _is_subject_to_discovery_stw(this),
1260 _ref_processor_cm(nullptr),
1261 _is_alive_closure_cm(this),
1262 _is_subject_to_discovery_cm(this),
1263 _region_attr() {
1264
1265 _verifier = new G1HeapVerifier(this);
1266
1267 _allocator = new G1Allocator(this);
1268
1269 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1270
1271 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1272
1273 // Override the default _filler_array_max_size so that no humongous filler
1274 // objects are created.
1275 _filler_array_max_size = _humongous_object_threshold_in_words;
1276
1277 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1278 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1279
1280 uint n_queues = ParallelGCThreads;
1281 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1282
1283 for (uint i = 0; i < n_queues; i++) {
1284 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1285 _task_queues->register_queue(i, q);
1286 }
1287
1288 _gc_tracer_stw->initialize();
1289
1290 guarantee(_task_queues != nullptr, "task_queues allocation failure.");
1291 }
1292
1293 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1294 size_t size,
1295 size_t translation_factor) {
1296 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1297 // Allocate a new reserved space, preferring to use large pages.
1298 ReservedSpace rs(size, preferred_page_size);
1299 size_t page_size = rs.page_size();
1300 G1RegionToSpaceMapper* result =
1301 G1RegionToSpaceMapper::create_mapper(rs,
1302 size,
1303 page_size,
1304 HeapRegion::GrainBytes,
1305 translation_factor,
1306 mtGC);
1307
1308 os::trace_page_sizes_for_requested_size(description,
1309 size,
1310 preferred_page_size,
1311 rs.base(),
1312 rs.size(),
1313 page_size);
1314
1315 return result;
1316 }
1317
1318 jint G1CollectedHeap::initialize_concurrent_refinement() {
1319 jint ecode = JNI_OK;
1320 _cr = G1ConcurrentRefine::create(policy(), &ecode);
1321 return ecode;
1322 }
1323
1324 jint G1CollectedHeap::initialize_service_thread() {
1325 _service_thread = new G1ServiceThread();
1326 if (_service_thread->osthread() == nullptr) {
1327 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1328 return JNI_ENOMEM;
1329 }
1330 return JNI_OK;
1331 }
1332
1333 jint G1CollectedHeap::initialize() {
1334
1335 // Necessary to satisfy locking discipline assertions.
1336
1337 MutexLocker x(Heap_lock);
1338
1339 // While there are no constraints in the GC code that HeapWordSize
1340 // be any particular value, there are multiple other areas in the
1341 // system which believe this to be true (e.g. oop->object_size in some
1342 // cases incorrectly returns the size in wordSize units rather than
1343 // HeapWordSize).
1344 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1345
1346 size_t init_byte_size = InitialHeapSize;
1347 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1348
1349 // Ensure that the sizes are properly aligned.
1350 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1351 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1352 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1353
1354 // Reserve the maximum.
1355
1356 // When compressed oops are enabled, the preferred heap base
1357 // is calculated by subtracting the requested size from the
1358 // 32Gb boundary and using the result as the base address for
1359 // heap reservation. If the requested size is not aligned to
1360 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1361 // into the ReservedHeapSpace constructor) then the actual
1362 // base of the reserved heap may end up differing from the
1363 // address that was requested (i.e. the preferred heap base).
1364 // If this happens then we could end up using a non-optimal
1365 // compressed oops mode.
1366
1367 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1368 HeapAlignment);
1369
1370 initialize_reserved_region(heap_rs);
1371
1372 // Create the barrier set for the entire reserved region.
1373 G1CardTable* ct = new G1CardTable(heap_rs.region());
1374 G1BarrierSet* bs = new G1BarrierSet(ct);
1375 bs->initialize();
1376 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1377 BarrierSet::set_barrier_set(bs);
1378 _card_table = ct;
1379
1380 {
1381 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1382 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1383 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1384 }
1385
1386 // Create space mappers.
1387 size_t page_size = heap_rs.page_size();
1388 G1RegionToSpaceMapper* heap_storage =
1389 G1RegionToSpaceMapper::create_mapper(heap_rs,
1390 heap_rs.size(),
1391 page_size,
1392 HeapRegion::GrainBytes,
1393 1,
1394 mtJavaHeap);
1395 if(heap_storage == nullptr) {
1396 vm_shutdown_during_initialization("Could not initialize G1 heap");
1397 return JNI_ERR;
1398 }
1399
1400 os::trace_page_sizes("Heap",
1401 MinHeapSize,
1402 reserved_byte_size,
1403 heap_rs.base(),
1404 heap_rs.size(),
1405 page_size);
1406 heap_storage->set_mapping_changed_listener(&_listener);
1407
1408 // Create storage for the BOT, card table and the bitmap.
1409 G1RegionToSpaceMapper* bot_storage =
1410 create_aux_memory_mapper("Block Offset Table",
1411 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1412 G1BlockOffsetTable::heap_map_factor());
1413
1414 G1RegionToSpaceMapper* cardtable_storage =
1415 create_aux_memory_mapper("Card Table",
1416 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1417 G1CardTable::heap_map_factor());
1418
1419 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1420 G1RegionToSpaceMapper* bitmap_storage =
1421 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1422
1423 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1424 _card_table->initialize(cardtable_storage);
1425
1426 // 6843694 - ensure that the maximum region index can fit
1427 // in the remembered set structures.
1428 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1429 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1430
1431 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1432 // start within the first card.
1433 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1434 G1FromCardCache::initialize(max_reserved_regions());
1435 // Also create a G1 rem set.
1436 _rem_set = new G1RemSet(this, _card_table);
1437 _rem_set->initialize(max_reserved_regions());
1438
1439 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1440 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1441 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1442 "too many cards per region");
1443
1444 HeapRegionRemSet::initialize(_reserved);
1445
1446 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1447
1448 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1449
1450 {
1451 size_t granularity = HeapRegion::GrainBytes;
1452
1453 _region_attr.initialize(reserved(), granularity);
1454 }
1455
1456 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1457 if (_workers == nullptr) {
1458 return JNI_ENOMEM;
1459 }
1460 _workers->initialize_workers();
1461
1462 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1463
1464 // Create the G1ConcurrentMark data structure and thread.
1465 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1466 _cm = new G1ConcurrentMark(this, bitmap_storage);
1467 _cm_thread = _cm->cm_thread();
1468
1469 // Now expand into the initial heap size.
1470 if (!expand(init_byte_size, _workers)) {
1471 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1472 return JNI_ENOMEM;
1473 }
1474
1475 // Perform any initialization actions delegated to the policy.
1476 policy()->init(this, &_collection_set);
1477
1478 jint ecode = initialize_concurrent_refinement();
1479 if (ecode != JNI_OK) {
1480 return ecode;
1481 }
1482
1483 ecode = initialize_service_thread();
1484 if (ecode != JNI_OK) {
1485 return ecode;
1486 }
1487
1488 // Create and schedule the periodic gc task on the service thread.
1489 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1490 _service_thread->register_task(_periodic_gc_task);
1491
1492 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1493 _service_thread->register_task(_free_arena_memory_task);
1494
1495 // Here we allocate the dummy HeapRegion that is required by the
1496 // G1AllocRegion class.
1497 HeapRegion* dummy_region = _hrm.get_dummy_region();
1498
1499 // We'll re-use the same region whether the alloc region will
1500 // require BOT updates or not and, if it doesn't, then a non-young
1501 // region will complain that it cannot support allocations without
1502 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1503 dummy_region->set_eden();
1504 // Make sure it's full.
1505 dummy_region->set_top(dummy_region->end());
1506 G1AllocRegion::setup(this, dummy_region);
1507
1508 _allocator->init_mutator_alloc_regions();
1509
1510 // Do create of the monitoring and management support so that
1511 // values in the heap have been properly initialized.
1512 _monitoring_support = new G1MonitoringSupport(this);
1513
1514 _collection_set.initialize(max_reserved_regions());
1515
1516 evac_failure_injector()->reset();
1517
1518 G1InitLogger::print();
1519
1520 return JNI_OK;
1521 }
1522
1523 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1524 return _cm_thread->should_terminate();
1525 }
1526
1527 void G1CollectedHeap::stop() {
1528 // Stop all concurrent threads. We do this to make sure these threads
1529 // do not continue to execute and access resources (e.g. logging)
1530 // that are destroyed during shutdown.
1531 _cr->stop();
1532 _service_thread->stop();
1533 _cm_thread->stop();
1534 }
1535
1536 void G1CollectedHeap::safepoint_synchronize_begin() {
1537 SuspendibleThreadSet::synchronize();
1538 }
1539
1540 void G1CollectedHeap::safepoint_synchronize_end() {
1541 SuspendibleThreadSet::desynchronize();
1542 }
1543
1544 void G1CollectedHeap::post_initialize() {
1545 CollectedHeap::post_initialize();
1546 ref_processing_init();
1547 }
1548
1549 void G1CollectedHeap::ref_processing_init() {
1550 // Reference processing in G1 currently works as follows:
1551 //
1552 // * There are two reference processor instances. One is
1553 // used to record and process discovered references
1554 // during concurrent marking; the other is used to
1555 // record and process references during STW pauses
1556 // (both full and incremental).
1557 // * Both ref processors need to 'span' the entire heap as
1558 // the regions in the collection set may be dotted around.
1559 //
1560 // * For the concurrent marking ref processor:
1561 // * Reference discovery is enabled at concurrent start.
1562 // * Reference discovery is disabled and the discovered
1563 // references processed etc during remarking.
1564 // * Reference discovery is MT (see below).
1565 // * Reference discovery requires a barrier (see below).
1566 // * Reference processing may or may not be MT
1567 // (depending on the value of ParallelRefProcEnabled
1568 // and ParallelGCThreads).
1569 // * A full GC disables reference discovery by the CM
1570 // ref processor and abandons any entries on it's
1571 // discovered lists.
1572 //
1573 // * For the STW processor:
1574 // * Non MT discovery is enabled at the start of a full GC.
1575 // * Processing and enqueueing during a full GC is non-MT.
1576 // * During a full GC, references are processed after marking.
1577 //
1578 // * Discovery (may or may not be MT) is enabled at the start
1579 // of an incremental evacuation pause.
1580 // * References are processed near the end of a STW evacuation pause.
1581 // * For both types of GC:
1582 // * Discovery is atomic - i.e. not concurrent.
1583 // * Reference discovery will not need a barrier.
1584
1585 // Concurrent Mark ref processor
1586 _ref_processor_cm =
1587 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1588 ParallelGCThreads, // degree of mt processing
1589 // We discover with the gc worker threads during Remark, so both
1590 // thread counts must be considered for discovery.
1591 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1592 true, // Reference discovery is concurrent
1593 &_is_alive_closure_cm); // is alive closure
1594
1595 // STW ref processor
1596 _ref_processor_stw =
1597 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1598 ParallelGCThreads, // degree of mt processing
1599 ParallelGCThreads, // degree of mt discovery
1600 false, // Reference discovery is not concurrent
1601 &_is_alive_closure_stw); // is alive closure
1602 }
1603
1604 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1605 return &_soft_ref_policy;
1606 }
1607
1608 size_t G1CollectedHeap::capacity() const {
1609 return _hrm.length() * HeapRegion::GrainBytes;
1610 }
1611
1612 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1613 return _hrm.total_free_bytes();
1614 }
1615
1616 // Computes the sum of the storage used by the various regions.
1617 size_t G1CollectedHeap::used() const {
1618 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1619 return result;
1620 }
1621
1622 size_t G1CollectedHeap::used_unlocked() const {
1623 return _summary_bytes_used;
1624 }
1625
1626 class SumUsedClosure: public HeapRegionClosure {
1627 size_t _used;
1628 public:
1629 SumUsedClosure() : _used(0) {}
1630 bool do_heap_region(HeapRegion* r) {
1631 _used += r->used();
1632 return false;
1633 }
1634 size_t result() { return _used; }
1635 };
1636
1637 size_t G1CollectedHeap::recalculate_used() const {
1638 SumUsedClosure blk;
1639 heap_region_iterate(&blk);
1640 return blk.result();
1641 }
1642
1643 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1644 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1645 }
1646
1647 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1648 switch (cause) {
1649 case GCCause::_g1_humongous_allocation: return true;
1650 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1651 case GCCause::_wb_breakpoint: return true;
1652 case GCCause::_codecache_GC_aggressive: return true;
1653 case GCCause::_codecache_GC_threshold: return true;
1654 default: return is_user_requested_concurrent_full_gc(cause);
1655 }
1656 }
1657
1658 void G1CollectedHeap::increment_old_marking_cycles_started() {
1659 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1660 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1661 "Wrong marking cycle count (started: %d, completed: %d)",
1662 _old_marking_cycles_started, _old_marking_cycles_completed);
1663
1664 _old_marking_cycles_started++;
1665 }
1666
1667 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1668 bool whole_heap_examined) {
1669 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1670
1671 // We assume that if concurrent == true, then the caller is a
1672 // concurrent thread that was joined the Suspendible Thread
1673 // Set. If there's ever a cheap way to check this, we should add an
1674 // assert here.
1675
1676 // Given that this method is called at the end of a Full GC or of a
1677 // concurrent cycle, and those can be nested (i.e., a Full GC can
1678 // interrupt a concurrent cycle), the number of full collections
1679 // completed should be either one (in the case where there was no
1680 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1681 // behind the number of full collections started.
1682
1683 // This is the case for the inner caller, i.e. a Full GC.
1684 assert(concurrent ||
1685 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1686 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1687 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1688 "is inconsistent with _old_marking_cycles_completed = %u",
1689 _old_marking_cycles_started, _old_marking_cycles_completed);
1690
1691 // This is the case for the outer caller, i.e. the concurrent cycle.
1692 assert(!concurrent ||
1693 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1694 "for outer caller (concurrent cycle): "
1695 "_old_marking_cycles_started = %u "
1696 "is inconsistent with _old_marking_cycles_completed = %u",
1697 _old_marking_cycles_started, _old_marking_cycles_completed);
1698
1699 _old_marking_cycles_completed += 1;
1700 if (whole_heap_examined) {
1701 // Signal that we have completed a visit to all live objects.
1702 record_whole_heap_examined_timestamp();
1703 }
1704
1705 // We need to clear the "in_progress" flag in the CM thread before
1706 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1707 // is set) so that if a waiter requests another System.gc() it doesn't
1708 // incorrectly see that a marking cycle is still in progress.
1709 if (concurrent) {
1710 _cm_thread->set_idle();
1711 }
1712
1713 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1714 // for a full GC to finish that their wait is over.
1715 ml.notify_all();
1716 }
1717
1718 // Helper for collect().
1719 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1720 MutexLocker ml(Heap_lock);
1721 return G1GCCounters(g1h);
1722 }
1723
1724 void G1CollectedHeap::collect(GCCause::Cause cause) {
1725 try_collect(cause, collection_counters(this));
1726 }
1727
1728 // Return true if (x < y) with allowance for wraparound.
1729 static bool gc_counter_less_than(uint x, uint y) {
1730 return (x - y) > (UINT_MAX/2);
1731 }
1732
1733 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1734 // Macro so msg printing is format-checked.
1735 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
1736 do { \
1737 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
1738 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
1739 ResourceMark rm; /* For thread name. */ \
1740 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1741 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1742 Thread::current()->name(), \
1743 GCCause::to_string(cause)); \
1744 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
1745 } \
1746 } while (0)
1747
1748 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1749 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1750
1751 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1752 uint gc_counter,
1753 uint old_marking_started_before) {
1754 assert_heap_not_locked();
1755 assert(should_do_concurrent_full_gc(cause),
1756 "Non-concurrent cause %s", GCCause::to_string(cause));
1757
1758 for (uint i = 1; true; ++i) {
1759 // Try to schedule concurrent start evacuation pause that will
1760 // start a concurrent cycle.
1761 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1762 VM_G1TryInitiateConcMark op(gc_counter, cause);
1763 VMThread::execute(&op);
1764
1765 // Request is trivially finished.
1766 if (cause == GCCause::_g1_periodic_collection) {
1767 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1768 return op.gc_succeeded();
1769 }
1770
1771 // If VMOp skipped initiating concurrent marking cycle because
1772 // we're terminating, then we're done.
1773 if (op.terminating()) {
1774 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1775 return false;
1776 }
1777
1778 // Lock to get consistent set of values.
1779 uint old_marking_started_after;
1780 uint old_marking_completed_after;
1781 {
1782 MutexLocker ml(Heap_lock);
1783 // Update gc_counter for retrying VMOp if needed. Captured here to be
1784 // consistent with the values we use below for termination tests. If
1785 // a retry is needed after a possible wait, and another collection
1786 // occurs in the meantime, it will cause our retry to be skipped and
1787 // we'll recheck for termination with updated conditions from that
1788 // more recent collection. That's what we want, rather than having
1789 // our retry possibly perform an unnecessary collection.
1790 gc_counter = total_collections();
1791 old_marking_started_after = _old_marking_cycles_started;
1792 old_marking_completed_after = _old_marking_cycles_completed;
1793 }
1794
1795 if (cause == GCCause::_wb_breakpoint) {
1796 if (op.gc_succeeded()) {
1797 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1798 return true;
1799 }
1800 // When _wb_breakpoint there can't be another cycle or deferred.
1801 assert(!op.cycle_already_in_progress(), "invariant");
1802 assert(!op.whitebox_attached(), "invariant");
1803 // Concurrent cycle attempt might have been cancelled by some other
1804 // collection, so retry. Unlike other cases below, we want to retry
1805 // even if cancelled by a STW full collection, because we really want
1806 // to start a concurrent cycle.
1807 if (old_marking_started_before != old_marking_started_after) {
1808 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1809 old_marking_started_before = old_marking_started_after;
1810 }
1811 } else if (!GCCause::is_user_requested_gc(cause)) {
1812 // For an "automatic" (not user-requested) collection, we just need to
1813 // ensure that progress is made.
1814 //
1815 // Request is finished if any of
1816 // (1) the VMOp successfully performed a GC,
1817 // (2) a concurrent cycle was already in progress,
1818 // (3) whitebox is controlling concurrent cycles,
1819 // (4) a new cycle was started (by this thread or some other), or
1820 // (5) a Full GC was performed.
1821 // Cases (4) and (5) are detected together by a change to
1822 // _old_marking_cycles_started.
1823 //
1824 // Note that (1) does not imply (4). If we're still in the mixed
1825 // phase of an earlier concurrent collection, the request to make the
1826 // collection a concurrent start won't be honored. If we don't check for
1827 // both conditions we'll spin doing back-to-back collections.
1828 if (op.gc_succeeded() ||
1829 op.cycle_already_in_progress() ||
1830 op.whitebox_attached() ||
1831 (old_marking_started_before != old_marking_started_after)) {
1832 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1833 return true;
1834 }
1835 } else { // User-requested GC.
1836 // For a user-requested collection, we want to ensure that a complete
1837 // full collection has been performed before returning, but without
1838 // waiting for more than needed.
1839
1840 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1841 // new cycle was started. That's good, because it's not clear what we
1842 // should do otherwise. Trying again just does back to back GCs.
1843 // Can't wait for someone else to start a cycle. And returning fails
1844 // to meet the goal of ensuring a full collection was performed.
1845 assert(!op.gc_succeeded() ||
1846 (old_marking_started_before != old_marking_started_after),
1847 "invariant: succeeded %s, started before %u, started after %u",
1848 BOOL_TO_STR(op.gc_succeeded()),
1849 old_marking_started_before, old_marking_started_after);
1850
1851 // Request is finished if a full collection (concurrent or stw)
1852 // was started after this request and has completed, e.g.
1853 // started_before < completed_after.
1854 if (gc_counter_less_than(old_marking_started_before,
1855 old_marking_completed_after)) {
1856 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1857 return true;
1858 }
1859
1860 if (old_marking_started_after != old_marking_completed_after) {
1861 // If there is an in-progress cycle (possibly started by us), then
1862 // wait for that cycle to complete, e.g.
1863 // while completed_now < started_after.
1864 LOG_COLLECT_CONCURRENTLY(cause, "wait");
1865 MonitorLocker ml(G1OldGCCount_lock);
1866 while (gc_counter_less_than(_old_marking_cycles_completed,
1867 old_marking_started_after)) {
1868 ml.wait();
1869 }
1870 // Request is finished if the collection we just waited for was
1871 // started after this request.
1872 if (old_marking_started_before != old_marking_started_after) {
1873 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
1874 return true;
1875 }
1876 }
1877
1878 // If VMOp was successful then it started a new cycle that the above
1879 // wait &etc should have recognized as finishing this request. This
1880 // differs from a non-user-request, where gc_succeeded does not imply
1881 // a new cycle was started.
1882 assert(!op.gc_succeeded(), "invariant");
1883
1884 if (op.cycle_already_in_progress()) {
1885 // If VMOp failed because a cycle was already in progress, it
1886 // is now complete. But it didn't finish this user-requested
1887 // GC, so try again.
1888 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
1889 continue;
1890 } else if (op.whitebox_attached()) {
1891 // If WhiteBox wants control, wait for notification of a state
1892 // change in the controller, then try again. Don't wait for
1893 // release of control, since collections may complete while in
1894 // control. Note: This won't recognize a STW full collection
1895 // while waiting; we can't wait on multiple monitors.
1896 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
1897 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
1898 if (ConcurrentGCBreakpoints::is_controlled()) {
1899 ml.wait();
1900 }
1901 continue;
1902 }
1903 }
1904
1905 // Collection failed and should be retried.
1906 assert(op.transient_failure(), "invariant");
1907
1908 if (GCLocker::is_active_and_needs_gc()) {
1909 // If GCLocker is active, wait until clear before retrying.
1910 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
1911 GCLocker::stall_until_clear();
1912 }
1913
1914 LOG_COLLECT_CONCURRENTLY(cause, "retry");
1915 }
1916 }
1917
1918 bool G1CollectedHeap::try_collect_fullgc(GCCause::Cause cause,
1919 const G1GCCounters& counters_before) {
1920 assert_heap_not_locked();
1921
1922 while(true) {
1923 VM_G1CollectFull op(counters_before.total_collections(),
1924 counters_before.total_full_collections(),
1925 cause);
1926 VMThread::execute(&op);
1927
1928 // Request is trivially finished.
1929 if (!GCCause::is_explicit_full_gc(cause) || op.gc_succeeded()) {
1930 return op.gc_succeeded();
1931 }
1932
1933 {
1934 MutexLocker ml(Heap_lock);
1935 if (counters_before.total_full_collections() != total_full_collections()) {
1936 return true;
1937 }
1938 }
1939
1940 if (GCLocker::is_active_and_needs_gc()) {
1941 // If GCLocker is active, wait until clear before retrying.
1942 GCLocker::stall_until_clear();
1943 }
1944 }
1945 }
1946
1947 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
1948 const G1GCCounters& counters_before) {
1949 if (should_do_concurrent_full_gc(cause)) {
1950 return try_collect_concurrently(cause,
1951 counters_before.total_collections(),
1952 counters_before.old_marking_cycles_started());
1953 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
1954 // Indicate failure to be consistent with VMOp failure due to
1955 // another collection slipping in after our gc_count but before
1956 // our request is processed.
1957 return false;
1958 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
1959 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1960
1961 // Schedule a standard evacuation pause. We're setting word_size
1962 // to 0 which means that we are not requesting a post-GC allocation.
1963 VM_G1CollectForAllocation op(0, /* word_size */
1964 counters_before.total_collections(),
1965 cause);
1966 VMThread::execute(&op);
1967 return op.gc_succeeded();
1968 } else {
1969 // Schedule a Full GC.
1970 return try_collect_fullgc(cause, counters_before);
1971 }
1972 }
1973
1974 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
1975 GCCauseSetter x(this, gc_cause);
1976
1977 // At this point we are supposed to start a concurrent cycle. We
1978 // will do so if one is not already in progress.
1979 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
1980 if (should_start) {
1981 do_collection_pause_at_safepoint();
1982 }
1983 }
1984
1985 bool G1CollectedHeap::is_in(const void* p) const {
1986 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
1987 }
1988
1989 // Iteration functions.
1990
1991 // Iterates an ObjectClosure over all objects within a HeapRegion.
1992
1993 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
1994 ObjectClosure* _cl;
1995 public:
1996 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
1997 bool do_heap_region(HeapRegion* r) {
1998 if (!r->is_continues_humongous()) {
1999 r->object_iterate(_cl);
2000 }
2001 return false;
2002 }
2003 };
2004
2005 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2006 IterateObjectClosureRegionClosure blk(cl);
2007 heap_region_iterate(&blk);
2008 }
2009
2010 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2011 private:
2012 G1CollectedHeap* _heap;
2013 HeapRegionClaimer _claimer;
2014
2015 public:
2016 G1ParallelObjectIterator(uint thread_num) :
2017 _heap(G1CollectedHeap::heap()),
2018 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2019
2020 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2021 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2022 }
2023 };
2024
2025 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2026 return new G1ParallelObjectIterator(thread_num);
2027 }
2028
2029 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2030 IterateObjectClosureRegionClosure blk(cl);
2031 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2032 }
2033
2034 void G1CollectedHeap::keep_alive(oop obj) {
2035 G1BarrierSet::enqueue_preloaded(obj);
2036 }
2037
2038 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2039 _hrm.iterate(cl);
2040 }
2041
2042 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
2043 _hrm.iterate(cl);
2044 }
2045
2046 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2047 HeapRegionClaimer *hrclaimer,
2048 uint worker_id) const {
2049 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2050 }
2051
2052 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2053 HeapRegionClaimer *hrclaimer) const {
2054 _hrm.par_iterate(cl, hrclaimer, 0);
2055 }
2056
2057 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2058 _collection_set.iterate(cl);
2059 }
2060
2061 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2062 HeapRegionClaimer* hr_claimer,
2063 uint worker_id) {
2064 _collection_set.par_iterate(cl, hr_claimer, worker_id);
2065 }
2066
2067 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2068 HeapRegionClaimer* hr_claimer,
2069 uint worker_id) {
2070 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2071 }
2072
2073 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2074 HeapRegionClaimer* hr_claimer,
2075 const uint regions[],
2076 size_t length,
2077 uint worker_id) const {
2078 assert_at_safepoint();
2079 if (length == 0) {
2080 return;
2081 }
2082 uint total_workers = workers()->active_workers();
2083
2084 size_t start_pos = (worker_id * length) / total_workers;
2085 size_t cur_pos = start_pos;
2086
2087 do {
2088 uint region_idx = regions[cur_pos];
2089 if (hr_claimer == nullptr || hr_claimer->claim_region(region_idx)) {
2090 HeapRegion* r = region_at(region_idx);
2091 bool result = cl->do_heap_region(r);
2092 guarantee(!result, "Must not cancel iteration");
2093 }
2094
2095 cur_pos++;
2096 if (cur_pos == length) {
2097 cur_pos = 0;
2098 }
2099 } while (cur_pos != start_pos);
2100 }
2101
2102 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2103 HeapRegion* hr = heap_region_containing(addr);
2104 // The CollectedHeap API requires us to not fail for any given address within
2105 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2106 // outside of the allocated area.
2107 if (addr >= hr->top()) {
2108 return nullptr;
2109 }
2110 return hr->block_start(addr);
2111 }
2112
2113 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2114 HeapRegion* hr = heap_region_containing(addr);
2115 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2116 }
2117
2118 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2119 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2120 }
2121
2122 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2123 return _eden.length() * HeapRegion::GrainBytes;
2124 }
2125
2126 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2127 // must be equal to the humongous object limit.
2128 size_t G1CollectedHeap::max_tlab_size() const {
2129 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2130 }
2131
2132 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2133 return _allocator->unsafe_max_tlab_alloc();
2134 }
2135
2136 size_t G1CollectedHeap::max_capacity() const {
2137 return max_regions() * HeapRegion::GrainBytes;
2138 }
2139
2140 void G1CollectedHeap::prepare_for_verify() {
2141 _verifier->prepare_for_verify();
2142 }
2143
2144 void G1CollectedHeap::verify(VerifyOption vo) {
2145 _verifier->verify(vo);
2146 }
2147
2148 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2149 return true;
2150 }
2151
2152 class PrintRegionClosure: public HeapRegionClosure {
2153 outputStream* _st;
2154 public:
2155 PrintRegionClosure(outputStream* st) : _st(st) {}
2156 bool do_heap_region(HeapRegion* r) {
2157 r->print_on(_st);
2158 return false;
2159 }
2160 };
2161
2162 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2163 const HeapRegion* hr,
2164 const VerifyOption vo) const {
2165 switch (vo) {
2166 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2167 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2168 default: ShouldNotReachHere();
2169 }
2170 return false; // keep some compilers happy
2171 }
2172
2173 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2174 const VerifyOption vo) const {
2175 switch (vo) {
2176 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2177 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2178 default: ShouldNotReachHere();
2179 }
2180 return false; // keep some compilers happy
2181 }
2182
2183 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) {
2184 GCLocker::lock_critical(thread);
2185 }
2186
2187 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
2188 GCLocker::unlock_critical(thread);
2189 }
2190
2191 void G1CollectedHeap::print_heap_regions() const {
2192 LogTarget(Trace, gc, heap, region) lt;
2193 if (lt.is_enabled()) {
2194 LogStream ls(lt);
2195 print_regions_on(&ls);
2196 }
2197 }
2198
2199 void G1CollectedHeap::print_on(outputStream* st) const {
2200 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2201 st->print(" %-20s", "garbage-first heap");
2202 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2203 capacity()/K, heap_used/K);
2204 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2205 p2i(_hrm.reserved().start()),
2206 p2i(_hrm.reserved().end()));
2207 st->cr();
2208 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2209 uint young_regions = young_regions_count();
2210 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2211 (size_t) young_regions * HeapRegion::GrainBytes / K);
2212 uint survivor_regions = survivor_regions_count();
2213 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2214 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2215 st->cr();
2216 if (_numa->is_enabled()) {
2217 uint num_nodes = _numa->num_active_nodes();
2218 st->print(" remaining free region(s) on each NUMA node: ");
2219 const int* node_ids = _numa->node_ids();
2220 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2221 uint num_free_regions = _hrm.num_free_regions(node_index);
2222 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2223 }
2224 st->cr();
2225 }
2226 MetaspaceUtils::print_on(st);
2227 }
2228
2229 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2230 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2231 "HS=humongous(starts), HC=humongous(continues), "
2232 "CS=collection set, F=free, "
2233 "TAMS=top-at-mark-start, "
2234 "PB=parsable bottom");
2235 PrintRegionClosure blk(st);
2236 heap_region_iterate(&blk);
2237 }
2238
2239 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2240 print_on(st);
2241
2242 // Print the per-region information.
2243 st->cr();
2244 print_regions_on(st);
2245 }
2246
2247 void G1CollectedHeap::print_on_error(outputStream* st) const {
2248 this->CollectedHeap::print_on_error(st);
2249
2250 if (_cm != nullptr) {
2251 st->cr();
2252 _cm->print_on_error(st);
2253 }
2254 }
2255
2256 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2257 workers()->threads_do(tc);
2258 tc->do_thread(_cm_thread);
2259 _cm->threads_do(tc);
2260 _cr->threads_do(tc);
2261 tc->do_thread(_service_thread);
2262 }
2263
2264 void G1CollectedHeap::print_tracing_info() const {
2265 rem_set()->print_summary_info();
2266 concurrent_mark()->print_summary_info();
2267 }
2268
2269 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2270 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2271 }
2272
2273 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2274
2275 size_t eden_used_bytes = _monitoring_support->eden_space_used();
2276 size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2277 size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2278 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2279
2280 size_t eden_capacity_bytes =
2281 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2282
2283 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2284 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2285 survivor_used_bytes, old_gen_used_bytes, num_regions());
2286 }
2287
2288 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2289 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2290 stats->unused(), stats->used(), stats->region_end_waste(),
2291 stats->regions_filled(), stats->num_plab_filled(),
2292 stats->direct_allocated(), stats->num_direct_allocated(),
2293 stats->failure_used(), stats->failure_waste());
2294 }
2295
2296 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2297 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2298 gc_tracer->report_gc_heap_summary(when, heap_summary);
2299
2300 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2301 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2302 }
2303
2304 void G1CollectedHeap::gc_prologue(bool full) {
2305 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2306
2307 // Update common counters.
2308 increment_total_collections(full /* full gc */);
2309 if (full || collector_state()->in_concurrent_start_gc()) {
2310 increment_old_marking_cycles_started();
2311 }
2312 }
2313
2314 void G1CollectedHeap::gc_epilogue(bool full) {
2315 // Update common counters.
2316 if (full) {
2317 // Update the number of full collections that have been completed.
2318 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2319 }
2320
2321 #if COMPILER2_OR_JVMCI
2322 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2323 #endif
2324
2325 // We have just completed a GC. Update the soft reference
2326 // policy with the new heap occupancy
2327 Universe::heap()->update_capacity_and_used_at_gc();
2328
2329 _collection_pause_end = Ticks::now();
2330
2331 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2332 &_collection_set_candidates_card_set_stats);
2333 }
2334
2335 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2336 return _hrm.uncommit_inactive_regions(region_limit);
2337 }
2338
2339 bool G1CollectedHeap::has_uncommittable_regions() {
2340 return _hrm.has_inactive_regions();
2341 }
2342
2343 void G1CollectedHeap::uncommit_regions_if_necessary() {
2344 if (has_uncommittable_regions()) {
2345 G1UncommitRegionTask::enqueue();
2346 }
2347 }
2348
2349 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2350 LogTarget(Trace, gc, heap, verify) lt;
2351
2352 if (lt.is_enabled()) {
2353 LogStream ls(lt);
2354 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2355 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2356 heap_region_iterate(&cl);
2357 }
2358 }
2359
2360 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2361 uint gc_count_before,
2362 bool* succeeded,
2363 GCCause::Cause gc_cause) {
2364 assert_heap_not_locked_and_not_at_safepoint();
2365 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2366 VMThread::execute(&op);
2367
2368 HeapWord* result = op.result();
2369 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2370 assert(result == nullptr || ret_succeeded,
2371 "the result should be null if the VM did not succeed");
2372 *succeeded = ret_succeeded;
2373
2374 assert_heap_not_locked();
2375 return result;
2376 }
2377
2378 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2379 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2380
2381 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2382 if (concurrent_operation_is_full_mark) {
2383 _cm->post_concurrent_mark_start();
2384 _cm_thread->start_full_mark();
2385 } else {
2386 _cm->post_concurrent_undo_start();
2387 _cm_thread->start_undo_mark();
2388 }
2389 CGC_lock->notify();
2390 }
2391
2392 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2393 // We don't nominate objects with many remembered set entries, on
2394 // the assumption that such objects are likely still live.
2395 HeapRegionRemSet* rem_set = r->rem_set();
2396
2397 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2398 }
2399
2400 #ifndef PRODUCT
2401 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2402 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2403 public:
2404 virtual bool do_heap_region(HeapRegion* r) {
2405 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2406 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2407 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2408 "Region %u remset tracking status (%s) different to region attribute (%s)",
2409 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2410 return false;
2411 }
2412 } cl;
2413 heap_region_iterate(&cl);
2414 }
2415 #endif
2416
2417 void G1CollectedHeap::start_new_collection_set() {
2418 collection_set()->start_incremental_building();
2419
2420 clear_region_attr();
2421
2422 guarantee(_eden.length() == 0, "eden should have been cleared");
2423 policy()->transfer_survivors_to_cset(survivor());
2424
2425 // We redo the verification but now wrt to the new CSet which
2426 // has just got initialized after the previous CSet was freed.
2427 _cm->verify_no_collection_set_oops();
2428 }
2429
2430 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2431 if (collector_state()->in_concurrent_start_gc()) {
2432 return G1HeapVerifier::G1VerifyConcurrentStart;
2433 } else if (collector_state()->in_young_only_phase()) {
2434 return G1HeapVerifier::G1VerifyYoungNormal;
2435 } else {
2436 return G1HeapVerifier::G1VerifyMixed;
2437 }
2438 }
2439
2440 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2441 if (!VerifyBeforeGC) {
2442 return;
2443 }
2444 if (!G1HeapVerifier::should_verify(type)) {
2445 return;
2446 }
2447 Ticks start = Ticks::now();
2448 _verifier->prepare_for_verify();
2449 _verifier->verify_region_sets_optional();
2450 _verifier->verify_dirty_young_regions();
2451 _verifier->verify_before_gc();
2452 verify_numa_regions("GC Start");
2453 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2454 }
2455
2456 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2457 if (!VerifyAfterGC) {
2458 return;
2459 }
2460 if (!G1HeapVerifier::should_verify(type)) {
2461 return;
2462 }
2463 Ticks start = Ticks::now();
2464 _verifier->verify_after_gc();
2465 verify_numa_regions("GC End");
2466 _verifier->verify_region_sets_optional();
2467
2468 if (collector_state()->in_concurrent_start_gc()) {
2469 log_debug(gc, verify)("Marking state");
2470 _verifier->verify_marking_state();
2471 }
2472
2473 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2474 }
2475
2476 void G1CollectedHeap::expand_heap_after_young_collection(){
2477 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2478 if (expand_bytes > 0) {
2479 // No need for an ergo logging here,
2480 // expansion_amount() does this when it returns a value > 0.
2481 double expand_ms = 0.0;
2482 if (!expand(expand_bytes, _workers, &expand_ms)) {
2483 // We failed to expand the heap. Cannot do anything about it.
2484 }
2485 phase_times()->record_expand_heap_time(expand_ms);
2486 }
2487 }
2488
2489 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2490 assert_at_safepoint_on_vm_thread();
2491 guarantee(!is_gc_active(), "collection is not reentrant");
2492
2493 if (GCLocker::check_active_before_gc()) {
2494 return false;
2495 }
2496
2497 do_collection_pause_at_safepoint_helper();
2498 return true;
2499 }
2500
2501 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2502 // This summary needs to be printed before incrementing total collections.
2503 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2504 _g1h->total_collections(),
2505 true /* show_thread_times */);
2506 _g1h->print_heap_before_gc();
2507 _g1h->print_heap_regions();
2508 }
2509
2510 G1HeapPrinterMark::~G1HeapPrinterMark() {
2511 _g1h->policy()->print_age_table();
2512 _g1h->rem_set()->print_coarsen_stats();
2513 // We are at the end of the GC. Total collections has already been increased.
2514 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2515 _g1h->total_collections() - 1,
2516 false /* show_thread_times */);
2517
2518 _heap_transition.print();
2519 _g1h->print_heap_regions();
2520 _g1h->print_heap_after_gc();
2521 // Print NUMA statistics.
2522 _g1h->numa()->print_statistics();
2523 }
2524
2525 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2526 _timer(timer), _tracer(tracer) {
2527
2528 _timer->register_gc_start();
2529 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2530 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2531 }
2532
2533 G1JFRTracerMark::~G1JFRTracerMark() {
2534 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2535 _timer->register_gc_end();
2536 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2537 }
2538
2539 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2540 Ticks start = Ticks::now();
2541
2542 _survivor_evac_stats.adjust_desired_plab_size();
2543 _old_evac_stats.adjust_desired_plab_size();
2544
2545 // Start a new incremental collection set for the mutator phase.
2546 start_new_collection_set();
2547 _allocator->init_mutator_alloc_regions();
2548
2549 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2550 }
2551
2552 void G1CollectedHeap::retire_tlabs() {
2553 ensure_parsability(true);
2554 }
2555
2556 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2557 ResourceMark rm;
2558
2559 IsGCActiveMark active_gc_mark;
2560 GCIdMark gc_id_mark;
2561 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2562
2563 GCTraceCPUTime tcpu(_gc_tracer_stw);
2564
2565 _bytes_used_during_gc = 0;
2566
2567 policy()->decide_on_concurrent_start_pause();
2568 // Record whether this pause may need to trigger a concurrent operation. Later,
2569 // when we signal the G1ConcurrentMarkThread, the collector state has already
2570 // been reset for the next pause.
2571 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2572
2573 // Perform the collection.
2574 G1YoungCollector collector(gc_cause());
2575 collector.collect();
2576
2577 // It should now be safe to tell the concurrent mark thread to start
2578 // without its logging output interfering with the logging output
2579 // that came from the pause.
2580 if (should_start_concurrent_mark_operation) {
2581 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2582 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2583 // thread(s) could be running concurrently with us. Make sure that anything
2584 // after this point does not assume that we are the only GC thread running.
2585 // Note: of course, the actual marking work will not start until the safepoint
2586 // itself is released in SuspendibleThreadSet::desynchronize().
2587 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2588 ConcurrentGCBreakpoints::notify_idle_to_active();
2589 }
2590 }
2591
2592 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2593 uint num_workers = workers()->active_workers();
2594 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2595 workers()->run_task(&unlink_task);
2596 }
2597
2598 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2599 assert(obj != nullptr, "must not be null");
2600 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2601 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2602 // may falsely indicate that this is not the case here: however the collection set only
2603 // contains old regions when concurrent mark is not running.
2604 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2605 }
2606
2607 void G1CollectedHeap::make_pending_list_reachable() {
2608 if (collector_state()->in_concurrent_start_gc()) {
2609 oop pll_head = Universe::reference_pending_list();
2610 if (pll_head != nullptr) {
2611 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2612 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2613 }
2614 }
2615 }
2616
2617 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2618 _num_humongous_objects = num_humongous_total;
2619 _num_humongous_reclaim_candidates = num_humongous_candidates;
2620 }
2621
2622 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2623 const G1CollectionSetCandidates* candidates = collection_set()->candidates();
2624 return !candidates->is_empty();
2625 }
2626
2627 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2628 _collection_set_candidates_card_set_stats = stats;
2629 }
2630
2631 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2632 _young_gen_card_set_stats = stats;
2633 }
2634
2635 void G1CollectedHeap::record_obj_copy_mem_stats() {
2636 policy()->old_gen_alloc_tracker()->
2637 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2638
2639 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2640 create_g1_evac_summary(&_old_evac_stats));
2641 }
2642
2643 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2644 concurrent_mark()->clear_bitmap_for_region(hr);
2645 }
2646
2647 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2648 assert(!hr->is_free(), "the region should not be free");
2649 assert(!hr->is_empty(), "the region should not be empty");
2650 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2651
2652 // Reset region metadata to allow reuse.
2653 hr->hr_clear(true /* clear_space */);
2654 _policy->remset_tracker()->update_at_free(hr);
2655
2656 if (free_list != nullptr) {
2657 free_list->add_ordered(hr);
2658 }
2659 }
2660
2661 void G1CollectedHeap::retain_region(HeapRegion* hr) {
2662 MutexLocker x(G1RareEvent_lock, Mutex::_no_safepoint_check_flag);
2663 collection_set()->candidates()->add_retained_region_unsorted(hr);
2664 }
2665
2666 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2667 FreeRegionList* free_list) {
2668 assert(hr->is_humongous(), "this is only for humongous regions");
2669 hr->clear_humongous();
2670 free_region(hr, free_list);
2671 }
2672
2673 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2674 const uint humongous_regions_removed) {
2675 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
2676 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2677 _old_set.bulk_remove(old_regions_removed);
2678 _humongous_set.bulk_remove(humongous_regions_removed);
2679 }
2680
2681 }
2682
2683 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2684 assert(list != nullptr, "list can't be null");
2685 if (!list->is_empty()) {
2686 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2687 _hrm.insert_list_into_free_list(list);
2688 }
2689 }
2690
2691 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2692 decrease_used(bytes);
2693 }
2694
2695 void G1CollectedHeap::clear_eden() {
2696 _eden.clear();
2697 }
2698
2699 void G1CollectedHeap::clear_collection_set() {
2700 collection_set()->clear();
2701 }
2702
2703 void G1CollectedHeap::rebuild_free_region_list() {
2704 Ticks start = Ticks::now();
2705 _hrm.rebuild_free_list(workers());
2706 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2707 }
2708
2709 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2710 public:
2711 virtual bool do_heap_region(HeapRegion* r) {
2712 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2713 G1CollectedHeap::heap()->clear_region_attr(r);
2714 r->clear_young_index_in_cset();
2715 return false;
2716 }
2717 };
2718
2719 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2720 G1AbandonCollectionSetClosure cl;
2721 collection_set_iterate_all(&cl);
2722
2723 collection_set->clear();
2724 collection_set->stop_incremental_building();
2725 }
2726
2727 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2728 return _allocator->is_retained_old_region(hr);
2729 }
2730
2731 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2732 _eden.add(hr);
2733 _policy->set_region_eden(hr);
2734 }
2735
2736 #ifdef ASSERT
2737
2738 class NoYoungRegionsClosure: public HeapRegionClosure {
2739 private:
2740 bool _success;
2741 public:
2742 NoYoungRegionsClosure() : _success(true) { }
2743 bool do_heap_region(HeapRegion* r) {
2744 if (r->is_young()) {
2745 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2746 p2i(r->bottom()), p2i(r->end()));
2747 _success = false;
2748 }
2749 return false;
2750 }
2751 bool success() { return _success; }
2752 };
2753
2754 bool G1CollectedHeap::check_young_list_empty() {
2755 bool ret = (young_regions_count() == 0);
2756
2757 NoYoungRegionsClosure closure;
2758 heap_region_iterate(&closure);
2759 ret = ret && closure.success();
2760
2761 return ret;
2762 }
2763
2764 #endif // ASSERT
2765
2766 // Remove the given HeapRegion from the appropriate region set.
2767 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2768 if (hr->is_humongous()) {
2769 _humongous_set.remove(hr);
2770 } else if (hr->is_old()) {
2771 _old_set.remove(hr);
2772 } else if (hr->is_young()) {
2773 // Note that emptying the eden and survivor lists is postponed and instead
2774 // done as the first step when rebuilding the regions sets again. The reason
2775 // for this is that during a full GC string deduplication needs to know if
2776 // a collected region was young or old when the full GC was initiated.
2777 hr->uninstall_surv_rate_group();
2778 } else {
2779 // We ignore free regions, we'll empty the free list afterwards.
2780 assert(hr->is_free(), "it cannot be another type");
2781 }
2782 }
2783
2784 void G1CollectedHeap::increase_used(size_t bytes) {
2785 _summary_bytes_used += bytes;
2786 }
2787
2788 void G1CollectedHeap::decrease_used(size_t bytes) {
2789 assert(_summary_bytes_used >= bytes,
2790 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2791 _summary_bytes_used, bytes);
2792 _summary_bytes_used -= bytes;
2793 }
2794
2795 void G1CollectedHeap::set_used(size_t bytes) {
2796 _summary_bytes_used = bytes;
2797 }
2798
2799 class RebuildRegionSetsClosure : public HeapRegionClosure {
2800 private:
2801 bool _free_list_only;
2802
2803 HeapRegionSet* _old_set;
2804 HeapRegionSet* _humongous_set;
2805
2806 HeapRegionManager* _hrm;
2807
2808 size_t _total_used;
2809
2810 public:
2811 RebuildRegionSetsClosure(bool free_list_only,
2812 HeapRegionSet* old_set,
2813 HeapRegionSet* humongous_set,
2814 HeapRegionManager* hrm) :
2815 _free_list_only(free_list_only), _old_set(old_set),
2816 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2817 assert(_hrm->num_free_regions() == 0, "pre-condition");
2818 if (!free_list_only) {
2819 assert(_old_set->is_empty(), "pre-condition");
2820 assert(_humongous_set->is_empty(), "pre-condition");
2821 }
2822 }
2823
2824 bool do_heap_region(HeapRegion* r) {
2825 if (r->is_empty()) {
2826 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2827 // Add free regions to the free list
2828 r->set_free();
2829 _hrm->insert_into_free_list(r);
2830 } else if (!_free_list_only) {
2831 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2832
2833 if (r->is_humongous()) {
2834 _humongous_set->add(r);
2835 } else {
2836 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2837 // We now move all (non-humongous, non-old) regions to old gen,
2838 // and register them as such.
2839 r->move_to_old();
2840 _old_set->add(r);
2841 }
2842 _total_used += r->used();
2843 }
2844
2845 return false;
2846 }
2847
2848 size_t total_used() {
2849 return _total_used;
2850 }
2851 };
2852
2853 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2854 assert_at_safepoint_on_vm_thread();
2855
2856 if (!free_list_only) {
2857 _eden.clear();
2858 _survivor.clear();
2859 }
2860
2861 RebuildRegionSetsClosure cl(free_list_only,
2862 &_old_set, &_humongous_set,
2863 &_hrm);
2864 heap_region_iterate(&cl);
2865
2866 if (!free_list_only) {
2867 set_used(cl.total_used());
2868 }
2869 assert_used_and_recalculate_used_equal(this);
2870 }
2871
2872 // Methods for the mutator alloc region
2873
2874 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
2875 bool force,
2876 uint node_index) {
2877 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2878 bool should_allocate = policy()->should_allocate_mutator_region();
2879 if (force || should_allocate) {
2880 HeapRegion* new_alloc_region = new_region(word_size,
2881 HeapRegionType::Eden,
2882 false /* do_expand */,
2883 node_index);
2884 if (new_alloc_region != nullptr) {
2885 set_region_short_lived_locked(new_alloc_region);
2886 _hr_printer.alloc(new_alloc_region, !should_allocate);
2887 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2888 return new_alloc_region;
2889 }
2890 }
2891 return nullptr;
2892 }
2893
2894 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
2895 size_t allocated_bytes) {
2896 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2897 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
2898
2899 collection_set()->add_eden_region(alloc_region);
2900 increase_used(allocated_bytes);
2901 _eden.add_used_bytes(allocated_bytes);
2902 _hr_printer.retire(alloc_region);
2903
2904 // We update the eden sizes here, when the region is retired,
2905 // instead of when it's allocated, since this is the point that its
2906 // used space has been recorded in _summary_bytes_used.
2907 monitoring_support()->update_eden_size();
2908 }
2909
2910 // Methods for the GC alloc regions
2911
2912 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
2913 if (dest.is_old()) {
2914 return true;
2915 } else {
2916 return survivor_regions_count() < policy()->max_survivor_regions();
2917 }
2918 }
2919
2920 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
2921 assert(FreeList_lock->owned_by_self(), "pre-condition");
2922
2923 if (!has_more_regions(dest)) {
2924 return nullptr;
2925 }
2926
2927 HeapRegionType type;
2928 if (dest.is_young()) {
2929 type = HeapRegionType::Survivor;
2930 } else {
2931 type = HeapRegionType::Old;
2932 }
2933
2934 HeapRegion* new_alloc_region = new_region(word_size,
2935 type,
2936 true /* do_expand */,
2937 node_index);
2938
2939 if (new_alloc_region != nullptr) {
2940 if (type.is_survivor()) {
2941 new_alloc_region->set_survivor();
2942 _survivor.add(new_alloc_region);
2943 register_new_survivor_region_with_region_attr(new_alloc_region);
2944 } else {
2945 new_alloc_region->set_old();
2946 }
2947 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2948 register_region_with_region_attr(new_alloc_region);
2949 _hr_printer.alloc(new_alloc_region);
2950 return new_alloc_region;
2951 }
2952 return nullptr;
2953 }
2954
2955 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
2956 size_t allocated_bytes,
2957 G1HeapRegionAttr dest) {
2958 _bytes_used_during_gc += allocated_bytes;
2959 if (dest.is_old()) {
2960 old_set_add(alloc_region);
2961 } else {
2962 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
2963 _survivor.add_used_bytes(allocated_bytes);
2964 }
2965
2966 bool const during_im = collector_state()->in_concurrent_start_gc();
2967 if (during_im && allocated_bytes > 0) {
2968 _cm->add_root_region(alloc_region);
2969 }
2970 _hr_printer.retire(alloc_region);
2971 }
2972
2973 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
2974 bool expanded = false;
2975 uint index = _hrm.find_highest_free(&expanded);
2976
2977 if (index != G1_NO_HRM_INDEX) {
2978 if (expanded) {
2979 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
2980 HeapRegion::GrainWords * HeapWordSize);
2981 }
2982 return _hrm.allocate_free_regions_starting_at(index, 1);
2983 }
2984 return nullptr;
2985 }
2986
2987 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
2988 assert(!_cm->is_marked_in_bitmap(obj), "must be");
2989
2990 _cm->raw_mark_in_bitmap(obj);
2991 }
2992
2993 // Optimized nmethod scanning
2994 class RegisterNMethodOopClosure: public OopClosure {
2995 G1CollectedHeap* _g1h;
2996 nmethod* _nm;
2997
2998 public:
2999 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3000 _g1h(g1h), _nm(nm) {}
3001
3002 void do_oop(oop* p) {
3003 oop heap_oop = RawAccess<>::oop_load(p);
3004 if (!CompressedOops::is_null(heap_oop)) {
3005 oop obj = CompressedOops::decode_not_null(heap_oop);
3006 HeapRegion* hr = _g1h->heap_region_containing(obj);
3007 assert(!hr->is_continues_humongous(),
3008 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3009 " starting at " HR_FORMAT,
3010 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3011
3012 // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3013 hr->add_code_root_locked(_nm);
3014 }
3015 }
3016
3017 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3018 };
3019
3020 class UnregisterNMethodOopClosure: public OopClosure {
3021 G1CollectedHeap* _g1h;
3022 nmethod* _nm;
3023
3024 public:
3025 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3026 _g1h(g1h), _nm(nm) {}
3027
3028 void do_oop(oop* p) {
3029 oop heap_oop = RawAccess<>::oop_load(p);
3030 if (!CompressedOops::is_null(heap_oop)) {
3031 oop obj = CompressedOops::decode_not_null(heap_oop);
3032 HeapRegion* hr = _g1h->heap_region_containing(obj);
3033 assert(!hr->is_continues_humongous(),
3034 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3035 " starting at " HR_FORMAT,
3036 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3037
3038 hr->remove_code_root(_nm);
3039 }
3040 }
3041
3042 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3043 };
3044
3045 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3046 guarantee(nm != nullptr, "sanity");
3047 RegisterNMethodOopClosure reg_cl(this, nm);
3048 nm->oops_do(®_cl);
3049 }
3050
3051 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3052 guarantee(nm != nullptr, "sanity");
3053 UnregisterNMethodOopClosure reg_cl(this, nm);
3054 nm->oops_do(®_cl, true);
3055 }
3056
3057 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3058 if (evacuation_failed) {
3059 // Reset the G1EvacuationFailureALot counters and flags
3060 evac_failure_injector()->reset();
3061
3062 set_used(recalculate_used());
3063 } else {
3064 // The "used" of the collection set have already been subtracted
3065 // when they were freed. Add in the bytes used.
3066 increase_used(_bytes_used_during_gc);
3067 }
3068 }
3069
3070 class RebuildCodeRootClosure: public CodeBlobClosure {
3071 G1CollectedHeap* _g1h;
3072
3073 public:
3074 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3075 _g1h(g1h) {}
3076
3077 void do_code_blob(CodeBlob* cb) {
3078 nmethod* nm = cb->as_nmethod_or_null();
3079 if (nm != nullptr) {
3080 _g1h->register_nmethod(nm);
3081 }
3082 }
3083 };
3084
3085 void G1CollectedHeap::rebuild_code_roots() {
3086 RebuildCodeRootClosure blob_cl(this);
3087 CodeCache::blobs_do(&blob_cl);
3088 }
3089
3090 void G1CollectedHeap::initialize_serviceability() {
3091 _monitoring_support->initialize_serviceability();
3092 }
3093
3094 MemoryUsage G1CollectedHeap::memory_usage() {
3095 return _monitoring_support->memory_usage();
3096 }
3097
3098 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3099 return _monitoring_support->memory_managers();
3100 }
3101
3102 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3103 return _monitoring_support->memory_pools();
3104 }
3105
3106 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3107 HeapRegion* region = heap_region_containing(start);
3108 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3109 }
3110
3111 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3112 // We can reach here with an active code cache marking cycle either because the
3113 // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3114 // concurrent start young collection was below the threshold) or aborted. See
3115 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code
3116 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3117 // still have to arm all nmethod entry barriers. They are needed for adding oop
3118 // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3119 if (!CodeCache::is_gc_marking_cycle_active()) {
3120 CodeCache::on_gc_marking_cycle_start();
3121 }
3122 if (concurrent_mark_start) {
3123 CodeCache::arm_all_nmethods();
3124 }
3125 }
3126
3127 void G1CollectedHeap::finish_codecache_marking_cycle() {
3128 CodeCache::on_gc_marking_cycle_finish();
3129 CodeCache::arm_all_nmethods();
3130 }