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.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "compiler/oopMap.hpp"
32 #include "gc/g1/g1Allocator.inline.hpp"
33 #include "gc/g1/g1Arguments.hpp"
34 #include "gc/g1/g1BarrierSet.hpp"
35 #include "gc/g1/g1BatchedTask.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectionSetCandidates.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1ConcurrentRefine.hpp"
41 #include "gc/g1/g1ConcurrentRefineThread.hpp"
42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
43 #include "gc/g1/g1DirtyCardQueue.hpp"
44 #include "gc/g1/g1EvacStats.inline.hpp"
45 #include "gc/g1/g1FullCollector.hpp"
46 #include "gc/g1/g1GCCounters.hpp"
47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
48 #include "gc/g1/g1GCPhaseTimes.hpp"
49 #include "gc/g1/g1GCPauseType.hpp"
50 #include "gc/g1/g1HeapSizingPolicy.hpp"
51 #include "gc/g1/g1HeapTransition.hpp"
52 #include "gc/g1/g1HeapVerifier.hpp"
53 #include "gc/g1/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 bool G1CollectedHeap::check_archive_addresses(MemRegion range) {
515 return _hrm.reserved().contains(range);
516 }
517
518 template <typename Func>
519 void G1CollectedHeap::iterate_regions_in_range(MemRegion range, const Func& func) {
520 // Mark each G1 region touched by the range as old, add it to
521 // the old set, and set top.
522 HeapRegion* curr_region = _hrm.addr_to_region(range.start());
523 HeapRegion* end_region = _hrm.addr_to_region(range.last());
524
525 while (curr_region != nullptr) {
526 bool is_last = curr_region == end_region;
527 HeapRegion* next_region = is_last ? nullptr : _hrm.next_region_in_heap(curr_region);
528
529 func(curr_region, is_last);
530
531 curr_region = next_region;
532 }
533 }
534
535 bool G1CollectedHeap::alloc_archive_regions(MemRegion range) {
536 assert(!is_init_completed(), "Expect to be called at JVM init time");
537 MutexLocker x(Heap_lock);
538
539 MemRegion reserved = _hrm.reserved();
540
541 // Temporarily disable pretouching of heap pages. This interface is used
542 // when mmap'ing archived heap data in, so pre-touching is wasted.
543 FlagSetting fs(AlwaysPreTouch, false);
544
545 // For the specified MemRegion range, allocate the corresponding G1
546 // region(s) and mark them as old region(s).
547 HeapWord* start_address = range.start();
548 size_t word_size = range.word_size();
549 HeapWord* last_address = range.last();
550 size_t commits = 0;
551
552 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
553 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
554 p2i(start_address), p2i(last_address));
555
556 // Perform the actual region allocation, exiting if it fails.
557 // Then note how much new space we have allocated.
558 if (!_hrm.allocate_containing_regions(range, &commits, workers())) {
559 return false;
560 }
561 increase_used(word_size * HeapWordSize);
562 if (commits != 0) {
563 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
564 HeapRegion::GrainWords * HeapWordSize * commits);
565
566 }
567
568 // Mark each G1 region touched by the range as old, add it to
569 // the old set, and set top.
570 auto set_region_to_old = [&] (HeapRegion* r, bool is_last) {
571 assert(r->is_empty(), "Region already in use (%u)", r->hrm_index());
572
573 HeapWord* top = is_last ? last_address + 1 : r->end();
574 r->set_top(top);
575
576 r->set_old();
577 _hr_printer.alloc(r);
578 _old_set.add(r);
579 };
580
581 iterate_regions_in_range(range, set_region_to_old);
582 return true;
583 }
584
585 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion range) {
586 assert(!is_init_completed(), "Expect to be called at JVM init time");
587
588 iterate_regions_in_range(range,
589 [&] (HeapRegion* r, bool is_last) {
590 r->update_bot();
591 });
592 }
593
594 void G1CollectedHeap::dealloc_archive_regions(MemRegion range) {
595 assert(!is_init_completed(), "Expect to be called at JVM init time");
596 MemRegion reserved = _hrm.reserved();
597 size_t size_used = 0;
598 uint shrink_count = 0;
599
600 // Free the G1 regions that are within the specified range.
601 MutexLocker x(Heap_lock);
602 HeapWord* start_address = range.start();
603 HeapWord* last_address = range.last();
604
605 assert(reserved.contains(start_address) && reserved.contains(last_address),
606 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
607 p2i(start_address), p2i(last_address));
608 size_used += range.byte_size();
609
610 // Free, empty and uncommit regions with CDS archive content.
611 auto dealloc_archive_region = [&] (HeapRegion* r, bool is_last) {
612 guarantee(r->is_old(), "Expected old region at index %u", r->hrm_index());
613 _old_set.remove(r);
614 r->set_free();
615 r->set_top(r->bottom());
616 _hrm.shrink_at(r->hrm_index(), 1);
617 shrink_count++;
618 };
619
620 iterate_regions_in_range(range, dealloc_archive_region);
621
622 if (shrink_count != 0) {
623 log_debug(gc, ergo, heap)("Attempt heap shrinking (CDS archive regions). Total size: " SIZE_FORMAT "B",
624 HeapRegion::GrainWords * HeapWordSize * shrink_count);
625 // Explicit uncommit.
626 uncommit_regions(shrink_count);
627 }
628 decrease_used(size_used);
629 }
630
631 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
632 size_t desired_word_size,
633 size_t* actual_word_size) {
634 assert_heap_not_locked_and_not_at_safepoint();
635 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
636 "be called for humongous allocation requests");
637
638 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
639
640 if (result == nullptr) {
641 *actual_word_size = desired_word_size;
642 result = attempt_allocation_slow(desired_word_size);
643 }
644
645 assert_heap_not_locked();
646 if (result != nullptr) {
647 assert(*actual_word_size != 0, "Actual size must have been set here");
648 dirty_young_block(result, *actual_word_size);
649 } else {
650 *actual_word_size = 0;
651 }
652
653 return result;
654 }
655
656 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
657 ResourceMark rm; // For retrieving the thread names in log messages.
658
659 // The structure of this method has a lot of similarities to
660 // attempt_allocation_slow(). The reason these two were not merged
661 // into a single one is that such a method would require several "if
662 // allocation is not humongous do this, otherwise do that"
663 // conditional paths which would obscure its flow. In fact, an early
664 // version of this code did use a unified method which was harder to
665 // follow and, as a result, it had subtle bugs that were hard to
666 // track down. So keeping these two methods separate allows each to
667 // be more readable. It will be good to keep these two in sync as
668 // much as possible.
669
670 assert_heap_not_locked_and_not_at_safepoint();
671 assert(is_humongous(word_size), "attempt_allocation_humongous() "
672 "should only be called for humongous allocations");
673
674 // Humongous objects can exhaust the heap quickly, so we should check if we
675 // need to start a marking cycle at each humongous object allocation. We do
676 // the check before we do the actual allocation. The reason for doing it
677 // before the allocation is that we avoid having to keep track of the newly
678 // allocated memory while we do a GC.
679 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
680 word_size)) {
681 collect(GCCause::_g1_humongous_allocation);
682 }
683
684 // We will loop until a) we manage to successfully perform the
685 // allocation or b) we successfully schedule a collection which
686 // fails to perform the allocation. b) is the only case when we'll
687 // return null.
688 HeapWord* result = nullptr;
689 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
690 bool should_try_gc;
691 uint gc_count_before;
692
693
694 {
695 MutexLocker x(Heap_lock);
696
697 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
698 // Given that humongous objects are not allocated in young
699 // regions, we'll first try to do the allocation without doing a
700 // collection hoping that there's enough space in the heap.
701 result = humongous_obj_allocate(word_size);
702 if (result != nullptr) {
703 policy()->old_gen_alloc_tracker()->
704 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
705 return result;
706 }
707
708 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
709 // the GCLocker initiated GC has been performed and then retry. This includes
710 // the case when the GC Locker is not active but has not been performed.
711 should_try_gc = !GCLocker::needs_gc();
712 // Read the GC count while still holding the Heap_lock.
713 gc_count_before = total_collections();
714 }
715
716 if (should_try_gc) {
717 bool succeeded;
718 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
719 if (result != nullptr) {
720 assert(succeeded, "only way to get back a non-null result");
721 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
722 Thread::current()->name(), p2i(result));
723 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
724 policy()->old_gen_alloc_tracker()->
725 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
726 return result;
727 }
728
729 if (succeeded) {
730 // We successfully scheduled a collection which failed to allocate. No
731 // point in trying to allocate further. We'll just return null.
732 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
733 SIZE_FORMAT " words", Thread::current()->name(), word_size);
734 return nullptr;
735 }
736 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
737 Thread::current()->name(), word_size);
738 } else {
739 // Failed to schedule a collection.
740 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
741 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
742 SIZE_FORMAT " words", Thread::current()->name(), word_size);
743 return nullptr;
744 }
745 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
746 // The GCLocker is either active or the GCLocker initiated
747 // GC has not yet been performed. Stall until it is and
748 // then retry the allocation.
749 GCLocker::stall_until_clear();
750 gclocker_retry_count += 1;
751 }
752
753
754 // We can reach here if we were unsuccessful in scheduling a
755 // collection (because another thread beat us to it) or if we were
756 // stalled due to the GC locker. In either can we should retry the
757 // allocation attempt in case another thread successfully
758 // performed a collection and reclaimed enough space.
759 // Humongous object allocation always needs a lock, so we wait for the retry
760 // in the next iteration of the loop, unlike for the regular iteration case.
761 // Give a warning if we seem to be looping forever.
762
763 if ((QueuedAllocationWarningCount > 0) &&
764 (try_count % QueuedAllocationWarningCount == 0)) {
765 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
766 Thread::current()->name(), try_count, word_size);
767 }
768 }
769
770 ShouldNotReachHere();
771 return nullptr;
772 }
773
774 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
775 bool expect_null_mutator_alloc_region) {
776 assert_at_safepoint_on_vm_thread();
777 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
778 "the current alloc region was unexpectedly found to be non-null");
779
780 if (!is_humongous(word_size)) {
781 return _allocator->attempt_allocation_locked(word_size);
782 } else {
783 HeapWord* result = humongous_obj_allocate(word_size);
784 if (result != nullptr && policy()->need_to_start_conc_mark("STW humongous allocation")) {
785 collector_state()->set_initiate_conc_mark_if_possible(true);
786 }
787 return result;
788 }
789
790 ShouldNotReachHere();
791 }
792
793 class PostCompactionPrinterClosure: public HeapRegionClosure {
794 private:
795 G1HRPrinter* _hr_printer;
796 public:
797 bool do_heap_region(HeapRegion* hr) {
798 assert(!hr->is_young(), "not expecting to find young regions");
799 _hr_printer->post_compaction(hr);
800 return false;
801 }
802
803 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
804 : _hr_printer(hr_printer) { }
805 };
806
807 void G1CollectedHeap::print_heap_after_full_collection() {
808 // Post collection region logging.
809 // We should do this after we potentially resize the heap so
810 // that all the COMMIT / UNCOMMIT events are generated before
811 // the compaction events.
812 if (_hr_printer.is_active()) {
813 PostCompactionPrinterClosure cl(hr_printer());
814 heap_region_iterate(&cl);
815 }
816 }
817
818 bool G1CollectedHeap::abort_concurrent_cycle() {
819 // Disable discovery and empty the discovered lists
820 // for the CM ref processor.
821 _ref_processor_cm->disable_discovery();
822 _ref_processor_cm->abandon_partial_discovery();
823 _ref_processor_cm->verify_no_references_recorded();
824
825 // Abandon current iterations of concurrent marking and concurrent
826 // refinement, if any are in progress.
827 return concurrent_mark()->concurrent_cycle_abort();
828 }
829
830 void G1CollectedHeap::prepare_heap_for_full_collection() {
831 // Make sure we'll choose a new allocation region afterwards.
832 _allocator->release_mutator_alloc_regions();
833 _allocator->abandon_gc_alloc_regions();
834
835 // We may have added regions to the current incremental collection
836 // set between the last GC or pause and now. We need to clear the
837 // incremental collection set and then start rebuilding it afresh
838 // after this full GC.
839 abandon_collection_set(collection_set());
840
841 _hrm.remove_all_free_regions();
842 }
843
844 void G1CollectedHeap::verify_before_full_collection() {
845 assert_used_and_recalculate_used_equal(this);
846 if (!VerifyBeforeGC) {
847 return;
848 }
849 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
850 return;
851 }
852 _verifier->verify_region_sets_optional();
853 _verifier->verify_before_gc();
854 _verifier->verify_bitmap_clear(true /* above_tams_only */);
855 }
856
857 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
858 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
859 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
860 DEBUG_ONLY(MetaspaceUtils::verify();)
861
862 // Prepare heap for normal collections.
863 assert(num_free_regions() == 0, "we should not have added any free regions");
864 rebuild_region_sets(false /* free_list_only */);
865 abort_refinement();
866 resize_heap_if_necessary();
867 uncommit_regions_if_necessary();
868
869 // Rebuild the code root lists for each region
870 rebuild_code_roots();
871
872 start_new_collection_set();
873 _allocator->init_mutator_alloc_regions();
874
875 // Post collection state updates.
876 MetaspaceGC::compute_new_size();
877 }
878
879 void G1CollectedHeap::abort_refinement() {
880 // Discard all remembered set updates and reset refinement statistics.
881 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
882 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
883 "DCQS should be empty");
884 concurrent_refine()->get_and_reset_refinement_stats();
885 }
886
887 void G1CollectedHeap::verify_after_full_collection() {
888 if (!VerifyAfterGC) {
889 return;
890 }
891 if (!G1HeapVerifier::should_verify(G1HeapVerifier::G1VerifyFull)) {
892 return;
893 }
894 _hrm.verify_optional();
895 _verifier->verify_region_sets_optional();
896 _verifier->verify_after_gc();
897 _verifier->verify_bitmap_clear(false /* above_tams_only */);
898
899 // At this point there should be no regions in the
900 // entire heap tagged as young.
901 assert(check_young_list_empty(), "young list should be empty at this point");
902
903 // Note: since we've just done a full GC, concurrent
904 // marking is no longer active. Therefore we need not
905 // re-enable reference discovery for the CM ref processor.
906 // That will be done at the start of the next marking cycle.
907 // We also know that the STW processor should no longer
908 // discover any new references.
909 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
910 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
911 _ref_processor_stw->verify_no_references_recorded();
912 _ref_processor_cm->verify_no_references_recorded();
913 }
914
915 bool G1CollectedHeap::do_full_collection(bool clear_all_soft_refs,
916 bool do_maximal_compaction) {
917 assert_at_safepoint_on_vm_thread();
918
919 if (GCLocker::check_active_before_gc()) {
920 // Full GC was not completed.
921 return false;
922 }
923
924 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
925 soft_ref_policy()->should_clear_all_soft_refs();
926
927 G1FullGCMark gc_mark;
928 GCTraceTime(Info, gc) tm("Pause Full", nullptr, gc_cause(), true);
929 G1FullCollector collector(this, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
930
931 collector.prepare_collection();
932 collector.collect();
933 collector.complete_collection();
934
935 // Full collection was successfully completed.
936 return true;
937 }
938
939 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
940 // Currently, there is no facility in the do_full_collection(bool) API to notify
941 // the caller that the collection did not succeed (e.g., because it was locked
942 // out by the GC locker). So, right now, we'll ignore the return value.
943
944 do_full_collection(clear_all_soft_refs,
945 false /* do_maximal_compaction */);
946 }
947
948 bool G1CollectedHeap::upgrade_to_full_collection() {
949 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
950 log_info(gc, ergo)("Attempting full compaction clearing soft references");
951 bool success = do_full_collection(true /* clear_all_soft_refs */,
952 false /* do_maximal_compaction */);
953 // do_full_collection only fails if blocked by GC locker and that can't
954 // be the case here since we only call this when already completed one gc.
955 assert(success, "invariant");
956 return success;
957 }
958
959 void G1CollectedHeap::resize_heap_if_necessary() {
960 assert_at_safepoint_on_vm_thread();
961
962 bool should_expand;
963 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
964
965 if (resize_amount == 0) {
966 return;
967 } else if (should_expand) {
968 expand(resize_amount, _workers);
969 } else {
970 shrink(resize_amount);
971 }
972 }
973
974 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
975 bool do_gc,
976 bool maximal_compaction,
977 bool expect_null_mutator_alloc_region,
978 bool* gc_succeeded) {
979 *gc_succeeded = true;
980 // Let's attempt the allocation first.
981 HeapWord* result =
982 attempt_allocation_at_safepoint(word_size,
983 expect_null_mutator_alloc_region);
984 if (result != nullptr) {
985 return result;
986 }
987
988 // In a G1 heap, we're supposed to keep allocation from failing by
989 // incremental pauses. Therefore, at least for now, we'll favor
990 // expansion over collection. (This might change in the future if we can
991 // do something smarter than full collection to satisfy a failed alloc.)
992 result = expand_and_allocate(word_size);
993 if (result != nullptr) {
994 return result;
995 }
996
997 if (do_gc) {
998 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
999 // Expansion didn't work, we'll try to do a Full GC.
1000 // If maximal_compaction is set we clear all soft references and don't
1001 // allow any dead wood to be left on the heap.
1002 if (maximal_compaction) {
1003 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
1004 } else {
1005 log_info(gc, ergo)("Attempting full compaction");
1006 }
1007 *gc_succeeded = do_full_collection(maximal_compaction /* clear_all_soft_refs */ ,
1008 maximal_compaction /* do_maximal_compaction */);
1009 }
1010
1011 return nullptr;
1012 }
1013
1014 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1015 bool* succeeded) {
1016 assert_at_safepoint_on_vm_thread();
1017
1018 // Attempts to allocate followed by Full GC.
1019 HeapWord* result =
1020 satisfy_failed_allocation_helper(word_size,
1021 true, /* do_gc */
1022 false, /* maximum_collection */
1023 false, /* expect_null_mutator_alloc_region */
1024 succeeded);
1025
1026 if (result != nullptr || !*succeeded) {
1027 return result;
1028 }
1029
1030 // Attempts to allocate followed by Full GC that will collect all soft references.
1031 result = satisfy_failed_allocation_helper(word_size,
1032 true, /* do_gc */
1033 true, /* maximum_collection */
1034 true, /* expect_null_mutator_alloc_region */
1035 succeeded);
1036
1037 if (result != nullptr || !*succeeded) {
1038 return result;
1039 }
1040
1041 // Attempts to allocate, no GC
1042 result = satisfy_failed_allocation_helper(word_size,
1043 false, /* do_gc */
1044 false, /* maximum_collection */
1045 true, /* expect_null_mutator_alloc_region */
1046 succeeded);
1047
1048 if (result != nullptr) {
1049 return result;
1050 }
1051
1052 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1053 "Flag should have been handled and cleared prior to this point");
1054
1055 // What else? We might try synchronous finalization later. If the total
1056 // space available is large enough for the allocation, then a more
1057 // complete compaction phase than we've tried so far might be
1058 // appropriate.
1059 return nullptr;
1060 }
1061
1062 // Attempting to expand the heap sufficiently
1063 // to support an allocation of the given "word_size". If
1064 // successful, perform the allocation and return the address of the
1065 // allocated block, or else null.
1066
1067 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1068 assert_at_safepoint_on_vm_thread();
1069
1070 _verifier->verify_region_sets_optional();
1071
1072 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1073 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1074 word_size * HeapWordSize);
1075
1076
1077 if (expand(expand_bytes, _workers)) {
1078 _hrm.verify_optional();
1079 _verifier->verify_region_sets_optional();
1080 return attempt_allocation_at_safepoint(word_size,
1081 false /* expect_null_mutator_alloc_region */);
1082 }
1083 return nullptr;
1084 }
1085
1086 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1087 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1088 aligned_expand_bytes = align_up(aligned_expand_bytes,
1089 HeapRegion::GrainBytes);
1090
1091 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1092 expand_bytes, aligned_expand_bytes);
1093
1094 if (is_maximal_no_gc()) {
1095 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1096 return false;
1097 }
1098
1099 double expand_heap_start_time_sec = os::elapsedTime();
1100 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1101 assert(regions_to_expand > 0, "Must expand by at least one region");
1102
1103 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1104 if (expand_time_ms != nullptr) {
1105 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1106 }
1107
1108 assert(expanded_by > 0, "must have failed during commit.");
1109
1110 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1111 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1112 policy()->record_new_heap_size(num_regions());
1113
1114 return true;
1115 }
1116
1117 bool G1CollectedHeap::expand_single_region(uint node_index) {
1118 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1119
1120 if (expanded_by == 0) {
1121 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1122 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1123 return false;
1124 }
1125
1126 policy()->record_new_heap_size(num_regions());
1127 return true;
1128 }
1129
1130 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1131 size_t aligned_shrink_bytes =
1132 ReservedSpace::page_align_size_down(shrink_bytes);
1133 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1134 HeapRegion::GrainBytes);
1135 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1136
1137 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1138 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1139
1140 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",
1141 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1142 if (num_regions_removed > 0) {
1143 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1144 policy()->record_new_heap_size(num_regions());
1145 } else {
1146 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1147 }
1148 }
1149
1150 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1151 _verifier->verify_region_sets_optional();
1152
1153 // We should only reach here at the end of a Full GC or during Remark which
1154 // means we should not not be holding to any GC alloc regions. The method
1155 // below will make sure of that and do any remaining clean up.
1156 _allocator->abandon_gc_alloc_regions();
1157
1158 // Instead of tearing down / rebuilding the free lists here, we
1159 // could instead use the remove_all_pending() method on free_list to
1160 // remove only the ones that we need to remove.
1161 _hrm.remove_all_free_regions();
1162 shrink_helper(shrink_bytes);
1163 rebuild_region_sets(true /* free_list_only */);
1164
1165 _hrm.verify_optional();
1166 _verifier->verify_region_sets_optional();
1167 }
1168
1169 class OldRegionSetChecker : public HeapRegionSetChecker {
1170 public:
1171 void check_mt_safety() {
1172 // Master Old Set MT safety protocol:
1173 // (a) If we're at a safepoint, operations on the master old set
1174 // should be invoked:
1175 // - by the VM thread (which will serialize them), or
1176 // - by the GC workers while holding the FreeList_lock, if we're
1177 // at a safepoint for an evacuation pause (this lock is taken
1178 // anyway when an GC alloc region is retired so that a new one
1179 // is allocated from the free list), or
1180 // - by the GC workers while holding the OldSets_lock, if we're at a
1181 // safepoint for a cleanup pause.
1182 // (b) If we're not at a safepoint, operations on the master old set
1183 // should be invoked while holding the Heap_lock.
1184
1185 if (SafepointSynchronize::is_at_safepoint()) {
1186 guarantee(Thread::current()->is_VM_thread() ||
1187 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1188 "master old set MT safety protocol at a safepoint");
1189 } else {
1190 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1191 }
1192 }
1193 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1194 const char* get_description() { return "Old Regions"; }
1195 };
1196
1197 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1198 public:
1199 void check_mt_safety() {
1200 // Humongous Set MT safety protocol:
1201 // (a) If we're at a safepoint, operations on the master humongous
1202 // set should be invoked by either the VM thread (which will
1203 // serialize them) or by the GC workers while holding the
1204 // OldSets_lock.
1205 // (b) If we're not at a safepoint, operations on the master
1206 // humongous set should be invoked while holding the Heap_lock.
1207
1208 if (SafepointSynchronize::is_at_safepoint()) {
1209 guarantee(Thread::current()->is_VM_thread() ||
1210 OldSets_lock->owned_by_self(),
1211 "master humongous set MT safety protocol at a safepoint");
1212 } else {
1213 guarantee(Heap_lock->owned_by_self(),
1214 "master humongous set MT safety protocol outside a safepoint");
1215 }
1216 }
1217 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1218 const char* get_description() { return "Humongous Regions"; }
1219 };
1220
1221 G1CollectedHeap::G1CollectedHeap() :
1222 CollectedHeap(),
1223 _service_thread(nullptr),
1224 _periodic_gc_task(nullptr),
1225 _free_arena_memory_task(nullptr),
1226 _workers(nullptr),
1227 _card_table(nullptr),
1228 _collection_pause_end(Ticks::now()),
1229 _soft_ref_policy(),
1230 _old_set("Old Region Set", new OldRegionSetChecker()),
1231 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1232 _bot(nullptr),
1233 _listener(),
1234 _numa(G1NUMA::create()),
1235 _hrm(),
1236 _allocator(nullptr),
1237 _evac_failure_injector(),
1238 _verifier(nullptr),
1239 _summary_bytes_used(0),
1240 _bytes_used_during_gc(0),
1241 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1242 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1243 _monitoring_support(nullptr),
1244 _num_humongous_objects(0),
1245 _num_humongous_reclaim_candidates(0),
1246 _hr_printer(),
1247 _collector_state(),
1248 _old_marking_cycles_started(0),
1249 _old_marking_cycles_completed(0),
1250 _eden(),
1251 _survivor(),
1252 _gc_timer_stw(new STWGCTimer()),
1253 _gc_tracer_stw(new G1NewTracer()),
1254 _policy(new G1Policy(_gc_timer_stw)),
1255 _heap_sizing_policy(nullptr),
1256 _collection_set(this, _policy),
1257 _rem_set(nullptr),
1258 _card_set_config(),
1259 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1260 _cm(nullptr),
1261 _cm_thread(nullptr),
1262 _cr(nullptr),
1263 _task_queues(nullptr),
1264 _ref_processor_stw(nullptr),
1265 _is_alive_closure_stw(this),
1266 _is_subject_to_discovery_stw(this),
1267 _ref_processor_cm(nullptr),
1268 _is_alive_closure_cm(this),
1269 _is_subject_to_discovery_cm(this),
1270 _region_attr() {
1271
1272 _verifier = new G1HeapVerifier(this);
1273
1274 _allocator = new G1Allocator(this);
1275
1276 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1277
1278 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1279
1280 // Override the default _filler_array_max_size so that no humongous filler
1281 // objects are created.
1282 _filler_array_max_size = _humongous_object_threshold_in_words;
1283
1284 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1285 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1286
1287 uint n_queues = ParallelGCThreads;
1288 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1289
1290 for (uint i = 0; i < n_queues; i++) {
1291 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1292 _task_queues->register_queue(i, q);
1293 }
1294
1295 _gc_tracer_stw->initialize();
1296
1297 guarantee(_task_queues != nullptr, "task_queues allocation failure.");
1298 }
1299
1300 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1301 size_t size,
1302 size_t translation_factor) {
1303 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1304 // Allocate a new reserved space, preferring to use large pages.
1305 ReservedSpace rs(size, preferred_page_size);
1306 size_t page_size = rs.page_size();
1307 G1RegionToSpaceMapper* result =
1308 G1RegionToSpaceMapper::create_mapper(rs,
1309 size,
1310 page_size,
1311 HeapRegion::GrainBytes,
1312 translation_factor,
1313 mtGC);
1314
1315 os::trace_page_sizes_for_requested_size(description,
1316 size,
1317 page_size,
1318 preferred_page_size,
1319 rs.base(),
1320 rs.size());
1321
1322 return result;
1323 }
1324
1325 jint G1CollectedHeap::initialize_concurrent_refinement() {
1326 jint ecode = JNI_OK;
1327 _cr = G1ConcurrentRefine::create(policy(), &ecode);
1328 return ecode;
1329 }
1330
1331 jint G1CollectedHeap::initialize_service_thread() {
1332 _service_thread = new G1ServiceThread();
1333 if (_service_thread->osthread() == nullptr) {
1334 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1335 return JNI_ENOMEM;
1336 }
1337 return JNI_OK;
1338 }
1339
1340 jint G1CollectedHeap::initialize() {
1341
1342 // Necessary to satisfy locking discipline assertions.
1343
1344 MutexLocker x(Heap_lock);
1345
1346 // While there are no constraints in the GC code that HeapWordSize
1347 // be any particular value, there are multiple other areas in the
1348 // system which believe this to be true (e.g. oop->object_size in some
1349 // cases incorrectly returns the size in wordSize units rather than
1350 // HeapWordSize).
1351 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1352
1353 size_t init_byte_size = InitialHeapSize;
1354 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1355
1356 // Ensure that the sizes are properly aligned.
1357 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1358 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1359 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1360
1361 // Reserve the maximum.
1362
1363 // When compressed oops are enabled, the preferred heap base
1364 // is calculated by subtracting the requested size from the
1365 // 32Gb boundary and using the result as the base address for
1366 // heap reservation. If the requested size is not aligned to
1367 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1368 // into the ReservedHeapSpace constructor) then the actual
1369 // base of the reserved heap may end up differing from the
1370 // address that was requested (i.e. the preferred heap base).
1371 // If this happens then we could end up using a non-optimal
1372 // compressed oops mode.
1373
1374 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1375 HeapAlignment);
1376
1377 initialize_reserved_region(heap_rs);
1378
1379 // Create the barrier set for the entire reserved region.
1380 G1CardTable* ct = new G1CardTable(heap_rs.region());
1381 G1BarrierSet* bs = new G1BarrierSet(ct);
1382 bs->initialize();
1383 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1384 BarrierSet::set_barrier_set(bs);
1385 _card_table = ct;
1386
1387 {
1388 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1389 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1390 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1391 }
1392
1393 // Create space mappers.
1394 size_t page_size = heap_rs.page_size();
1395 G1RegionToSpaceMapper* heap_storage =
1396 G1RegionToSpaceMapper::create_mapper(heap_rs,
1397 heap_rs.size(),
1398 page_size,
1399 HeapRegion::GrainBytes,
1400 1,
1401 mtJavaHeap);
1402 if(heap_storage == nullptr) {
1403 vm_shutdown_during_initialization("Could not initialize G1 heap");
1404 return JNI_ERR;
1405 }
1406
1407 os::trace_page_sizes("Heap",
1408 MinHeapSize,
1409 reserved_byte_size,
1410 page_size,
1411 heap_rs.base(),
1412 heap_rs.size());
1413 heap_storage->set_mapping_changed_listener(&_listener);
1414
1415 // Create storage for the BOT, card table and the bitmap.
1416 G1RegionToSpaceMapper* bot_storage =
1417 create_aux_memory_mapper("Block Offset Table",
1418 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1419 G1BlockOffsetTable::heap_map_factor());
1420
1421 G1RegionToSpaceMapper* cardtable_storage =
1422 create_aux_memory_mapper("Card Table",
1423 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1424 G1CardTable::heap_map_factor());
1425
1426 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1427 G1RegionToSpaceMapper* bitmap_storage =
1428 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1429
1430 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1431 _card_table->initialize(cardtable_storage);
1432
1433 // 6843694 - ensure that the maximum region index can fit
1434 // in the remembered set structures.
1435 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1436 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1437
1438 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1439 // start within the first card.
1440 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1441 G1FromCardCache::initialize(max_reserved_regions());
1442 // Also create a G1 rem set.
1443 _rem_set = new G1RemSet(this, _card_table);
1444 _rem_set->initialize(max_reserved_regions());
1445
1446 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1447 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1448 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1449 "too many cards per region");
1450
1451 HeapRegionRemSet::initialize(_reserved);
1452
1453 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1454
1455 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1456
1457 {
1458 size_t granularity = HeapRegion::GrainBytes;
1459
1460 _region_attr.initialize(reserved(), granularity);
1461 }
1462
1463 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1464 if (_workers == nullptr) {
1465 return JNI_ENOMEM;
1466 }
1467 _workers->initialize_workers();
1468
1469 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1470
1471 // Create the G1ConcurrentMark data structure and thread.
1472 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1473 _cm = new G1ConcurrentMark(this, bitmap_storage);
1474 _cm_thread = _cm->cm_thread();
1475
1476 // Now expand into the initial heap size.
1477 if (!expand(init_byte_size, _workers)) {
1478 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1479 return JNI_ENOMEM;
1480 }
1481
1482 // Perform any initialization actions delegated to the policy.
1483 policy()->init(this, &_collection_set);
1484
1485 jint ecode = initialize_concurrent_refinement();
1486 if (ecode != JNI_OK) {
1487 return ecode;
1488 }
1489
1490 ecode = initialize_service_thread();
1491 if (ecode != JNI_OK) {
1492 return ecode;
1493 }
1494
1495 // Create and schedule the periodic gc task on the service thread.
1496 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1497 _service_thread->register_task(_periodic_gc_task);
1498
1499 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1500 _service_thread->register_task(_free_arena_memory_task);
1501
1502 // Here we allocate the dummy HeapRegion that is required by the
1503 // G1AllocRegion class.
1504 HeapRegion* dummy_region = _hrm.get_dummy_region();
1505
1506 // We'll re-use the same region whether the alloc region will
1507 // require BOT updates or not and, if it doesn't, then a non-young
1508 // region will complain that it cannot support allocations without
1509 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1510 dummy_region->set_eden();
1511 // Make sure it's full.
1512 dummy_region->set_top(dummy_region->end());
1513 G1AllocRegion::setup(this, dummy_region);
1514
1515 _allocator->init_mutator_alloc_regions();
1516
1517 // Do create of the monitoring and management support so that
1518 // values in the heap have been properly initialized.
1519 _monitoring_support = new G1MonitoringSupport(this);
1520
1521 _collection_set.initialize(max_reserved_regions());
1522
1523 evac_failure_injector()->reset();
1524
1525 G1InitLogger::print();
1526
1527 return JNI_OK;
1528 }
1529
1530 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1531 return _cm_thread->should_terminate();
1532 }
1533
1534 void G1CollectedHeap::stop() {
1535 // Stop all concurrent threads. We do this to make sure these threads
1536 // do not continue to execute and access resources (e.g. logging)
1537 // that are destroyed during shutdown.
1538 _cr->stop();
1539 _service_thread->stop();
1540 _cm_thread->stop();
1541 }
1542
1543 void G1CollectedHeap::safepoint_synchronize_begin() {
1544 SuspendibleThreadSet::synchronize();
1545 }
1546
1547 void G1CollectedHeap::safepoint_synchronize_end() {
1548 SuspendibleThreadSet::desynchronize();
1549 }
1550
1551 void G1CollectedHeap::post_initialize() {
1552 CollectedHeap::post_initialize();
1553 ref_processing_init();
1554 }
1555
1556 void G1CollectedHeap::ref_processing_init() {
1557 // Reference processing in G1 currently works as follows:
1558 //
1559 // * There are two reference processor instances. One is
1560 // used to record and process discovered references
1561 // during concurrent marking; the other is used to
1562 // record and process references during STW pauses
1563 // (both full and incremental).
1564 // * Both ref processors need to 'span' the entire heap as
1565 // the regions in the collection set may be dotted around.
1566 //
1567 // * For the concurrent marking ref processor:
1568 // * Reference discovery is enabled at concurrent start.
1569 // * Reference discovery is disabled and the discovered
1570 // references processed etc during remarking.
1571 // * Reference discovery is MT (see below).
1572 // * Reference discovery requires a barrier (see below).
1573 // * Reference processing may or may not be MT
1574 // (depending on the value of ParallelRefProcEnabled
1575 // and ParallelGCThreads).
1576 // * A full GC disables reference discovery by the CM
1577 // ref processor and abandons any entries on it's
1578 // discovered lists.
1579 //
1580 // * For the STW processor:
1581 // * Non MT discovery is enabled at the start of a full GC.
1582 // * Processing and enqueueing during a full GC is non-MT.
1583 // * During a full GC, references are processed after marking.
1584 //
1585 // * Discovery (may or may not be MT) is enabled at the start
1586 // of an incremental evacuation pause.
1587 // * References are processed near the end of a STW evacuation pause.
1588 // * For both types of GC:
1589 // * Discovery is atomic - i.e. not concurrent.
1590 // * Reference discovery will not need a barrier.
1591
1592 // Concurrent Mark ref processor
1593 _ref_processor_cm =
1594 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1595 ParallelGCThreads, // degree of mt processing
1596 // We discover with the gc worker threads during Remark, so both
1597 // thread counts must be considered for discovery.
1598 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1599 true, // Reference discovery is concurrent
1600 &_is_alive_closure_cm); // is alive closure
1601
1602 // STW ref processor
1603 _ref_processor_stw =
1604 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1605 ParallelGCThreads, // degree of mt processing
1606 ParallelGCThreads, // degree of mt discovery
1607 false, // Reference discovery is not concurrent
1608 &_is_alive_closure_stw); // is alive closure
1609 }
1610
1611 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1612 return &_soft_ref_policy;
1613 }
1614
1615 size_t G1CollectedHeap::capacity() const {
1616 return _hrm.length() * HeapRegion::GrainBytes;
1617 }
1618
1619 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1620 return _hrm.total_free_bytes();
1621 }
1622
1623 // Computes the sum of the storage used by the various regions.
1624 size_t G1CollectedHeap::used() const {
1625 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1626 return result;
1627 }
1628
1629 size_t G1CollectedHeap::used_unlocked() const {
1630 return _summary_bytes_used;
1631 }
1632
1633 class SumUsedClosure: public HeapRegionClosure {
1634 size_t _used;
1635 public:
1636 SumUsedClosure() : _used(0) {}
1637 bool do_heap_region(HeapRegion* r) {
1638 _used += r->used();
1639 return false;
1640 }
1641 size_t result() { return _used; }
1642 };
1643
1644 size_t G1CollectedHeap::recalculate_used() const {
1645 SumUsedClosure blk;
1646 heap_region_iterate(&blk);
1647 return blk.result();
1648 }
1649
1650 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1651 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1652 }
1653
1654 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1655 switch (cause) {
1656 case GCCause::_g1_humongous_allocation: return true;
1657 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1658 case GCCause::_wb_breakpoint: return true;
1659 case GCCause::_codecache_GC_aggressive: return true;
1660 case GCCause::_codecache_GC_threshold: return true;
1661 default: return is_user_requested_concurrent_full_gc(cause);
1662 }
1663 }
1664
1665 void G1CollectedHeap::increment_old_marking_cycles_started() {
1666 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1667 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1668 "Wrong marking cycle count (started: %d, completed: %d)",
1669 _old_marking_cycles_started, _old_marking_cycles_completed);
1670
1671 _old_marking_cycles_started++;
1672 }
1673
1674 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1675 bool whole_heap_examined) {
1676 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1677
1678 // We assume that if concurrent == true, then the caller is a
1679 // concurrent thread that was joined the Suspendible Thread
1680 // Set. If there's ever a cheap way to check this, we should add an
1681 // assert here.
1682
1683 // Given that this method is called at the end of a Full GC or of a
1684 // concurrent cycle, and those can be nested (i.e., a Full GC can
1685 // interrupt a concurrent cycle), the number of full collections
1686 // completed should be either one (in the case where there was no
1687 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1688 // behind the number of full collections started.
1689
1690 // This is the case for the inner caller, i.e. a Full GC.
1691 assert(concurrent ||
1692 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1693 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1694 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1695 "is inconsistent with _old_marking_cycles_completed = %u",
1696 _old_marking_cycles_started, _old_marking_cycles_completed);
1697
1698 // This is the case for the outer caller, i.e. the concurrent cycle.
1699 assert(!concurrent ||
1700 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1701 "for outer caller (concurrent cycle): "
1702 "_old_marking_cycles_started = %u "
1703 "is inconsistent with _old_marking_cycles_completed = %u",
1704 _old_marking_cycles_started, _old_marking_cycles_completed);
1705
1706 _old_marking_cycles_completed += 1;
1707 if (whole_heap_examined) {
1708 // Signal that we have completed a visit to all live objects.
1709 record_whole_heap_examined_timestamp();
1710 }
1711
1712 // We need to clear the "in_progress" flag in the CM thread before
1713 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1714 // is set) so that if a waiter requests another System.gc() it doesn't
1715 // incorrectly see that a marking cycle is still in progress.
1716 if (concurrent) {
1717 _cm_thread->set_idle();
1718 }
1719
1720 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1721 // for a full GC to finish that their wait is over.
1722 ml.notify_all();
1723 }
1724
1725 // Helper for collect().
1726 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1727 MutexLocker ml(Heap_lock);
1728 return G1GCCounters(g1h);
1729 }
1730
1731 void G1CollectedHeap::collect(GCCause::Cause cause) {
1732 try_collect(cause, collection_counters(this));
1733 }
1734
1735 // Return true if (x < y) with allowance for wraparound.
1736 static bool gc_counter_less_than(uint x, uint y) {
1737 return (x - y) > (UINT_MAX/2);
1738 }
1739
1740 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1741 // Macro so msg printing is format-checked.
1742 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
1743 do { \
1744 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
1745 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
1746 ResourceMark rm; /* For thread name. */ \
1747 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1748 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1749 Thread::current()->name(), \
1750 GCCause::to_string(cause)); \
1751 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
1752 } \
1753 } while (0)
1754
1755 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1756 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1757
1758 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1759 uint gc_counter,
1760 uint old_marking_started_before) {
1761 assert_heap_not_locked();
1762 assert(should_do_concurrent_full_gc(cause),
1763 "Non-concurrent cause %s", GCCause::to_string(cause));
1764
1765 for (uint i = 1; true; ++i) {
1766 // Try to schedule concurrent start evacuation pause that will
1767 // start a concurrent cycle.
1768 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1769 VM_G1TryInitiateConcMark op(gc_counter, cause);
1770 VMThread::execute(&op);
1771
1772 // Request is trivially finished.
1773 if (cause == GCCause::_g1_periodic_collection) {
1774 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1775 return op.gc_succeeded();
1776 }
1777
1778 // If VMOp skipped initiating concurrent marking cycle because
1779 // we're terminating, then we're done.
1780 if (op.terminating()) {
1781 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1782 return false;
1783 }
1784
1785 // Lock to get consistent set of values.
1786 uint old_marking_started_after;
1787 uint old_marking_completed_after;
1788 {
1789 MutexLocker ml(Heap_lock);
1790 // Update gc_counter for retrying VMOp if needed. Captured here to be
1791 // consistent with the values we use below for termination tests. If
1792 // a retry is needed after a possible wait, and another collection
1793 // occurs in the meantime, it will cause our retry to be skipped and
1794 // we'll recheck for termination with updated conditions from that
1795 // more recent collection. That's what we want, rather than having
1796 // our retry possibly perform an unnecessary collection.
1797 gc_counter = total_collections();
1798 old_marking_started_after = _old_marking_cycles_started;
1799 old_marking_completed_after = _old_marking_cycles_completed;
1800 }
1801
1802 if (cause == GCCause::_wb_breakpoint) {
1803 if (op.gc_succeeded()) {
1804 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1805 return true;
1806 }
1807 // When _wb_breakpoint there can't be another cycle or deferred.
1808 assert(!op.cycle_already_in_progress(), "invariant");
1809 assert(!op.whitebox_attached(), "invariant");
1810 // Concurrent cycle attempt might have been cancelled by some other
1811 // collection, so retry. Unlike other cases below, we want to retry
1812 // even if cancelled by a STW full collection, because we really want
1813 // to start a concurrent cycle.
1814 if (old_marking_started_before != old_marking_started_after) {
1815 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1816 old_marking_started_before = old_marking_started_after;
1817 }
1818 } else if (!GCCause::is_user_requested_gc(cause)) {
1819 // For an "automatic" (not user-requested) collection, we just need to
1820 // ensure that progress is made.
1821 //
1822 // Request is finished if any of
1823 // (1) the VMOp successfully performed a GC,
1824 // (2) a concurrent cycle was already in progress,
1825 // (3) whitebox is controlling concurrent cycles,
1826 // (4) a new cycle was started (by this thread or some other), or
1827 // (5) a Full GC was performed.
1828 // Cases (4) and (5) are detected together by a change to
1829 // _old_marking_cycles_started.
1830 //
1831 // Note that (1) does not imply (4). If we're still in the mixed
1832 // phase of an earlier concurrent collection, the request to make the
1833 // collection a concurrent start won't be honored. If we don't check for
1834 // both conditions we'll spin doing back-to-back collections.
1835 if (op.gc_succeeded() ||
1836 op.cycle_already_in_progress() ||
1837 op.whitebox_attached() ||
1838 (old_marking_started_before != old_marking_started_after)) {
1839 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1840 return true;
1841 }
1842 } else { // User-requested GC.
1843 // For a user-requested collection, we want to ensure that a complete
1844 // full collection has been performed before returning, but without
1845 // waiting for more than needed.
1846
1847 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1848 // new cycle was started. That's good, because it's not clear what we
1849 // should do otherwise. Trying again just does back to back GCs.
1850 // Can't wait for someone else to start a cycle. And returning fails
1851 // to meet the goal of ensuring a full collection was performed.
1852 assert(!op.gc_succeeded() ||
1853 (old_marking_started_before != old_marking_started_after),
1854 "invariant: succeeded %s, started before %u, started after %u",
1855 BOOL_TO_STR(op.gc_succeeded()),
1856 old_marking_started_before, old_marking_started_after);
1857
1858 // Request is finished if a full collection (concurrent or stw)
1859 // was started after this request and has completed, e.g.
1860 // started_before < completed_after.
1861 if (gc_counter_less_than(old_marking_started_before,
1862 old_marking_completed_after)) {
1863 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1864 return true;
1865 }
1866
1867 if (old_marking_started_after != old_marking_completed_after) {
1868 // If there is an in-progress cycle (possibly started by us), then
1869 // wait for that cycle to complete, e.g.
1870 // while completed_now < started_after.
1871 LOG_COLLECT_CONCURRENTLY(cause, "wait");
1872 MonitorLocker ml(G1OldGCCount_lock);
1873 while (gc_counter_less_than(_old_marking_cycles_completed,
1874 old_marking_started_after)) {
1875 ml.wait();
1876 }
1877 // Request is finished if the collection we just waited for was
1878 // started after this request.
1879 if (old_marking_started_before != old_marking_started_after) {
1880 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
1881 return true;
1882 }
1883 }
1884
1885 // If VMOp was successful then it started a new cycle that the above
1886 // wait &etc should have recognized as finishing this request. This
1887 // differs from a non-user-request, where gc_succeeded does not imply
1888 // a new cycle was started.
1889 assert(!op.gc_succeeded(), "invariant");
1890
1891 if (op.cycle_already_in_progress()) {
1892 // If VMOp failed because a cycle was already in progress, it
1893 // is now complete. But it didn't finish this user-requested
1894 // GC, so try again.
1895 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
1896 continue;
1897 } else if (op.whitebox_attached()) {
1898 // If WhiteBox wants control, wait for notification of a state
1899 // change in the controller, then try again. Don't wait for
1900 // release of control, since collections may complete while in
1901 // control. Note: This won't recognize a STW full collection
1902 // while waiting; we can't wait on multiple monitors.
1903 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
1904 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
1905 if (ConcurrentGCBreakpoints::is_controlled()) {
1906 ml.wait();
1907 }
1908 continue;
1909 }
1910 }
1911
1912 // Collection failed and should be retried.
1913 assert(op.transient_failure(), "invariant");
1914
1915 if (GCLocker::is_active_and_needs_gc()) {
1916 // If GCLocker is active, wait until clear before retrying.
1917 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
1918 GCLocker::stall_until_clear();
1919 }
1920
1921 LOG_COLLECT_CONCURRENTLY(cause, "retry");
1922 }
1923 }
1924
1925 bool G1CollectedHeap::try_collect_fullgc(GCCause::Cause cause,
1926 const G1GCCounters& counters_before) {
1927 assert_heap_not_locked();
1928
1929 while(true) {
1930 VM_G1CollectFull op(counters_before.total_collections(),
1931 counters_before.total_full_collections(),
1932 cause);
1933 VMThread::execute(&op);
1934
1935 // Request is trivially finished.
1936 if (!GCCause::is_explicit_full_gc(cause) || op.gc_succeeded()) {
1937 return op.gc_succeeded();
1938 }
1939
1940 {
1941 MutexLocker ml(Heap_lock);
1942 if (counters_before.total_full_collections() != total_full_collections()) {
1943 return true;
1944 }
1945 }
1946
1947 if (GCLocker::is_active_and_needs_gc()) {
1948 // If GCLocker is active, wait until clear before retrying.
1949 GCLocker::stall_until_clear();
1950 }
1951 }
1952 }
1953
1954 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
1955 const G1GCCounters& counters_before) {
1956 if (should_do_concurrent_full_gc(cause)) {
1957 return try_collect_concurrently(cause,
1958 counters_before.total_collections(),
1959 counters_before.old_marking_cycles_started());
1960 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
1961 // Indicate failure to be consistent with VMOp failure due to
1962 // another collection slipping in after our gc_count but before
1963 // our request is processed.
1964 return false;
1965 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
1966 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
1967
1968 // Schedule a standard evacuation pause. We're setting word_size
1969 // to 0 which means that we are not requesting a post-GC allocation.
1970 VM_G1CollectForAllocation op(0, /* word_size */
1971 counters_before.total_collections(),
1972 cause);
1973 VMThread::execute(&op);
1974 return op.gc_succeeded();
1975 } else {
1976 // Schedule a Full GC.
1977 return try_collect_fullgc(cause, counters_before);
1978 }
1979 }
1980
1981 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
1982 GCCauseSetter x(this, gc_cause);
1983
1984 // At this point we are supposed to start a concurrent cycle. We
1985 // will do so if one is not already in progress.
1986 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
1987 if (should_start) {
1988 do_collection_pause_at_safepoint();
1989 }
1990 }
1991
1992 bool G1CollectedHeap::is_in(const void* p) const {
1993 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
1994 }
1995
1996 // Iteration functions.
1997
1998 // Iterates an ObjectClosure over all objects within a HeapRegion.
1999
2000 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2001 ObjectClosure* _cl;
2002 public:
2003 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2004 bool do_heap_region(HeapRegion* r) {
2005 if (!r->is_continues_humongous()) {
2006 r->object_iterate(_cl);
2007 }
2008 return false;
2009 }
2010 };
2011
2012 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2013 IterateObjectClosureRegionClosure blk(cl);
2014 heap_region_iterate(&blk);
2015 }
2016
2017 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2018 private:
2019 G1CollectedHeap* _heap;
2020 HeapRegionClaimer _claimer;
2021
2022 public:
2023 G1ParallelObjectIterator(uint thread_num) :
2024 _heap(G1CollectedHeap::heap()),
2025 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2026
2027 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2028 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2029 }
2030 };
2031
2032 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2033 return new G1ParallelObjectIterator(thread_num);
2034 }
2035
2036 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2037 IterateObjectClosureRegionClosure blk(cl);
2038 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2039 }
2040
2041 void G1CollectedHeap::keep_alive(oop obj) {
2042 G1BarrierSet::enqueue_preloaded(obj);
2043 }
2044
2045 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2046 _hrm.iterate(cl);
2047 }
2048
2049 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
2050 _hrm.iterate(cl);
2051 }
2052
2053 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2054 HeapRegionClaimer *hrclaimer,
2055 uint worker_id) const {
2056 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2057 }
2058
2059 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2060 HeapRegionClaimer *hrclaimer) const {
2061 _hrm.par_iterate(cl, hrclaimer, 0);
2062 }
2063
2064 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2065 _collection_set.iterate(cl);
2066 }
2067
2068 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2069 HeapRegionClaimer* hr_claimer,
2070 uint worker_id) {
2071 _collection_set.par_iterate(cl, hr_claimer, worker_id);
2072 }
2073
2074 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2075 HeapRegionClaimer* hr_claimer,
2076 uint worker_id) {
2077 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2078 }
2079
2080 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2081 HeapRegionClaimer* hr_claimer,
2082 const uint regions[],
2083 size_t length,
2084 uint worker_id) const {
2085 assert_at_safepoint();
2086 if (length == 0) {
2087 return;
2088 }
2089 uint total_workers = workers()->active_workers();
2090
2091 size_t start_pos = (worker_id * length) / total_workers;
2092 size_t cur_pos = start_pos;
2093
2094 do {
2095 uint region_idx = regions[cur_pos];
2096 if (hr_claimer == nullptr || hr_claimer->claim_region(region_idx)) {
2097 HeapRegion* r = region_at(region_idx);
2098 bool result = cl->do_heap_region(r);
2099 guarantee(!result, "Must not cancel iteration");
2100 }
2101
2102 cur_pos++;
2103 if (cur_pos == length) {
2104 cur_pos = 0;
2105 }
2106 } while (cur_pos != start_pos);
2107 }
2108
2109 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2110 HeapRegion* hr = heap_region_containing(addr);
2111 // The CollectedHeap API requires us to not fail for any given address within
2112 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2113 // outside of the allocated area.
2114 if (addr >= hr->top()) {
2115 return nullptr;
2116 }
2117 return hr->block_start(addr);
2118 }
2119
2120 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2121 HeapRegion* hr = heap_region_containing(addr);
2122 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2123 }
2124
2125 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2126 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2127 }
2128
2129 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2130 return _eden.length() * HeapRegion::GrainBytes;
2131 }
2132
2133 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2134 // must be equal to the humongous object limit.
2135 size_t G1CollectedHeap::max_tlab_size() const {
2136 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2137 }
2138
2139 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2140 return _allocator->unsafe_max_tlab_alloc();
2141 }
2142
2143 size_t G1CollectedHeap::max_capacity() const {
2144 return max_regions() * HeapRegion::GrainBytes;
2145 }
2146
2147 void G1CollectedHeap::prepare_for_verify() {
2148 _verifier->prepare_for_verify();
2149 }
2150
2151 void G1CollectedHeap::verify(VerifyOption vo) {
2152 _verifier->verify(vo);
2153 }
2154
2155 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2156 return true;
2157 }
2158
2159 class PrintRegionClosure: public HeapRegionClosure {
2160 outputStream* _st;
2161 public:
2162 PrintRegionClosure(outputStream* st) : _st(st) {}
2163 bool do_heap_region(HeapRegion* r) {
2164 r->print_on(_st);
2165 return false;
2166 }
2167 };
2168
2169 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2170 const HeapRegion* hr,
2171 const VerifyOption vo) const {
2172 switch (vo) {
2173 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2174 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2175 default: ShouldNotReachHere();
2176 }
2177 return false; // keep some compilers happy
2178 }
2179
2180 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2181 const VerifyOption vo) const {
2182 switch (vo) {
2183 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2184 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2185 default: ShouldNotReachHere();
2186 }
2187 return false; // keep some compilers happy
2188 }
2189
2190 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) {
2191 GCLocker::lock_critical(thread);
2192 }
2193
2194 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
2195 GCLocker::unlock_critical(thread);
2196 }
2197
2198 void G1CollectedHeap::print_heap_regions() const {
2199 LogTarget(Trace, gc, heap, region) lt;
2200 if (lt.is_enabled()) {
2201 LogStream ls(lt);
2202 print_regions_on(&ls);
2203 }
2204 }
2205
2206 void G1CollectedHeap::print_on(outputStream* st) const {
2207 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2208 st->print(" %-20s", "garbage-first heap");
2209 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2210 capacity()/K, heap_used/K);
2211 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2212 p2i(_hrm.reserved().start()),
2213 p2i(_hrm.reserved().end()));
2214 st->cr();
2215 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2216 uint young_regions = young_regions_count();
2217 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2218 (size_t) young_regions * HeapRegion::GrainBytes / K);
2219 uint survivor_regions = survivor_regions_count();
2220 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2221 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2222 st->cr();
2223 if (_numa->is_enabled()) {
2224 uint num_nodes = _numa->num_active_nodes();
2225 st->print(" remaining free region(s) on each NUMA node: ");
2226 const int* node_ids = _numa->node_ids();
2227 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2228 uint num_free_regions = _hrm.num_free_regions(node_index);
2229 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2230 }
2231 st->cr();
2232 }
2233 MetaspaceUtils::print_on(st);
2234 }
2235
2236 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2237 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2238 "HS=humongous(starts), HC=humongous(continues), "
2239 "CS=collection set, F=free, "
2240 "TAMS=top-at-mark-start, "
2241 "PB=parsable bottom");
2242 PrintRegionClosure blk(st);
2243 heap_region_iterate(&blk);
2244 }
2245
2246 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2247 print_on(st);
2248
2249 // Print the per-region information.
2250 st->cr();
2251 print_regions_on(st);
2252 }
2253
2254 void G1CollectedHeap::print_on_error(outputStream* st) const {
2255 this->CollectedHeap::print_on_error(st);
2256
2257 if (_cm != nullptr) {
2258 st->cr();
2259 _cm->print_on_error(st);
2260 }
2261 }
2262
2263 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2264 workers()->threads_do(tc);
2265 tc->do_thread(_cm_thread);
2266 _cm->threads_do(tc);
2267 _cr->threads_do(tc);
2268 tc->do_thread(_service_thread);
2269 }
2270
2271 void G1CollectedHeap::print_tracing_info() const {
2272 rem_set()->print_summary_info();
2273 concurrent_mark()->print_summary_info();
2274 }
2275
2276 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2277 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2278 }
2279
2280 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2281
2282 size_t eden_used_bytes = _monitoring_support->eden_space_used();
2283 size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2284 size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2285 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2286
2287 size_t eden_capacity_bytes =
2288 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2289
2290 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2291 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2292 survivor_used_bytes, old_gen_used_bytes, num_regions());
2293 }
2294
2295 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2296 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2297 stats->unused(), stats->used(), stats->region_end_waste(),
2298 stats->regions_filled(), stats->num_plab_filled(),
2299 stats->direct_allocated(), stats->num_direct_allocated(),
2300 stats->failure_used(), stats->failure_waste());
2301 }
2302
2303 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2304 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2305 gc_tracer->report_gc_heap_summary(when, heap_summary);
2306
2307 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2308 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2309 }
2310
2311 void G1CollectedHeap::gc_prologue(bool full) {
2312 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2313
2314 // Update common counters.
2315 increment_total_collections(full /* full gc */);
2316 if (full || collector_state()->in_concurrent_start_gc()) {
2317 increment_old_marking_cycles_started();
2318 }
2319 }
2320
2321 void G1CollectedHeap::gc_epilogue(bool full) {
2322 // Update common counters.
2323 if (full) {
2324 // Update the number of full collections that have been completed.
2325 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2326 }
2327
2328 #if COMPILER2_OR_JVMCI
2329 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2330 #endif
2331
2332 // We have just completed a GC. Update the soft reference
2333 // policy with the new heap occupancy
2334 Universe::heap()->update_capacity_and_used_at_gc();
2335
2336 _collection_pause_end = Ticks::now();
2337
2338 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2339 &_collection_set_candidates_card_set_stats);
2340 }
2341
2342 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2343 return _hrm.uncommit_inactive_regions(region_limit);
2344 }
2345
2346 bool G1CollectedHeap::has_uncommittable_regions() {
2347 return _hrm.has_inactive_regions();
2348 }
2349
2350 void G1CollectedHeap::uncommit_regions_if_necessary() {
2351 if (has_uncommittable_regions()) {
2352 G1UncommitRegionTask::enqueue();
2353 }
2354 }
2355
2356 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2357 LogTarget(Trace, gc, heap, verify) lt;
2358
2359 if (lt.is_enabled()) {
2360 LogStream ls(lt);
2361 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2362 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2363 heap_region_iterate(&cl);
2364 }
2365 }
2366
2367 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2368 uint gc_count_before,
2369 bool* succeeded,
2370 GCCause::Cause gc_cause) {
2371 assert_heap_not_locked_and_not_at_safepoint();
2372 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2373 VMThread::execute(&op);
2374
2375 HeapWord* result = op.result();
2376 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2377 assert(result == nullptr || ret_succeeded,
2378 "the result should be null if the VM did not succeed");
2379 *succeeded = ret_succeeded;
2380
2381 assert_heap_not_locked();
2382 return result;
2383 }
2384
2385 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2386 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2387
2388 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2389 if (concurrent_operation_is_full_mark) {
2390 _cm->post_concurrent_mark_start();
2391 _cm_thread->start_full_mark();
2392 } else {
2393 _cm->post_concurrent_undo_start();
2394 _cm_thread->start_undo_mark();
2395 }
2396 CGC_lock->notify();
2397 }
2398
2399 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2400 // We don't nominate objects with many remembered set entries, on
2401 // the assumption that such objects are likely still live.
2402 HeapRegionRemSet* rem_set = r->rem_set();
2403
2404 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2405 }
2406
2407 #ifndef PRODUCT
2408 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2409 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2410 public:
2411 virtual bool do_heap_region(HeapRegion* r) {
2412 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2413 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2414 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2415 "Region %u remset tracking status (%s) different to region attribute (%s)",
2416 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2417 return false;
2418 }
2419 } cl;
2420 heap_region_iterate(&cl);
2421 }
2422 #endif
2423
2424 void G1CollectedHeap::start_new_collection_set() {
2425 collection_set()->start_incremental_building();
2426
2427 clear_region_attr();
2428
2429 guarantee(_eden.length() == 0, "eden should have been cleared");
2430 policy()->transfer_survivors_to_cset(survivor());
2431
2432 // We redo the verification but now wrt to the new CSet which
2433 // has just got initialized after the previous CSet was freed.
2434 _cm->verify_no_collection_set_oops();
2435 }
2436
2437 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2438 if (collector_state()->in_concurrent_start_gc()) {
2439 return G1HeapVerifier::G1VerifyConcurrentStart;
2440 } else if (collector_state()->in_young_only_phase()) {
2441 return G1HeapVerifier::G1VerifyYoungNormal;
2442 } else {
2443 return G1HeapVerifier::G1VerifyMixed;
2444 }
2445 }
2446
2447 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2448 if (!VerifyBeforeGC) {
2449 return;
2450 }
2451 if (!G1HeapVerifier::should_verify(type)) {
2452 return;
2453 }
2454 Ticks start = Ticks::now();
2455 _verifier->prepare_for_verify();
2456 _verifier->verify_region_sets_optional();
2457 _verifier->verify_dirty_young_regions();
2458 _verifier->verify_before_gc();
2459 verify_numa_regions("GC Start");
2460 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2461 }
2462
2463 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2464 if (!VerifyAfterGC) {
2465 return;
2466 }
2467 if (!G1HeapVerifier::should_verify(type)) {
2468 return;
2469 }
2470 Ticks start = Ticks::now();
2471 _verifier->verify_after_gc();
2472 verify_numa_regions("GC End");
2473 _verifier->verify_region_sets_optional();
2474 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2475 }
2476
2477 void G1CollectedHeap::expand_heap_after_young_collection(){
2478 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2479 if (expand_bytes > 0) {
2480 // No need for an ergo logging here,
2481 // expansion_amount() does this when it returns a value > 0.
2482 double expand_ms = 0.0;
2483 if (!expand(expand_bytes, _workers, &expand_ms)) {
2484 // We failed to expand the heap. Cannot do anything about it.
2485 }
2486 phase_times()->record_expand_heap_time(expand_ms);
2487 }
2488 }
2489
2490 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2491 assert_at_safepoint_on_vm_thread();
2492 guarantee(!is_gc_active(), "collection is not reentrant");
2493
2494 if (GCLocker::check_active_before_gc()) {
2495 return false;
2496 }
2497
2498 do_collection_pause_at_safepoint_helper();
2499 return true;
2500 }
2501
2502 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2503 // This summary needs to be printed before incrementing total collections.
2504 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2505 _g1h->total_collections(),
2506 true /* show_thread_times */);
2507 _g1h->print_heap_before_gc();
2508 _g1h->print_heap_regions();
2509 }
2510
2511 G1HeapPrinterMark::~G1HeapPrinterMark() {
2512 _g1h->policy()->print_age_table();
2513 _g1h->rem_set()->print_coarsen_stats();
2514 // We are at the end of the GC. Total collections has already been increased.
2515 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2516 _g1h->total_collections() - 1,
2517 false /* show_thread_times */);
2518
2519 _heap_transition.print();
2520 _g1h->print_heap_regions();
2521 _g1h->print_heap_after_gc();
2522 // Print NUMA statistics.
2523 _g1h->numa()->print_statistics();
2524 }
2525
2526 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2527 _timer(timer), _tracer(tracer) {
2528
2529 _timer->register_gc_start();
2530 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2531 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2532 }
2533
2534 G1JFRTracerMark::~G1JFRTracerMark() {
2535 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2536 _timer->register_gc_end();
2537 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2538 }
2539
2540 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2541 Ticks start = Ticks::now();
2542
2543 _survivor_evac_stats.adjust_desired_plab_size();
2544 _old_evac_stats.adjust_desired_plab_size();
2545
2546 // Start a new incremental collection set for the mutator phase.
2547 start_new_collection_set();
2548 _allocator->init_mutator_alloc_regions();
2549
2550 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2551 }
2552
2553 void G1CollectedHeap::retire_tlabs() {
2554 ensure_parsability(true);
2555 }
2556
2557 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2558 ResourceMark rm;
2559
2560 IsGCActiveMark active_gc_mark;
2561 GCIdMark gc_id_mark;
2562 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2563
2564 GCTraceCPUTime tcpu(_gc_tracer_stw);
2565
2566 _bytes_used_during_gc = 0;
2567
2568 policy()->decide_on_concurrent_start_pause();
2569 // Record whether this pause may need to trigger a concurrent operation. Later,
2570 // when we signal the G1ConcurrentMarkThread, the collector state has already
2571 // been reset for the next pause.
2572 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2573
2574 // Perform the collection.
2575 G1YoungCollector collector(gc_cause());
2576 collector.collect();
2577
2578 // It should now be safe to tell the concurrent mark thread to start
2579 // without its logging output interfering with the logging output
2580 // that came from the pause.
2581 if (should_start_concurrent_mark_operation) {
2582 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2583 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2584 // thread(s) could be running concurrently with us. Make sure that anything
2585 // after this point does not assume that we are the only GC thread running.
2586 // Note: of course, the actual marking work will not start until the safepoint
2587 // itself is released in SuspendibleThreadSet::desynchronize().
2588 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2589 ConcurrentGCBreakpoints::notify_idle_to_active();
2590 }
2591 }
2592
2593 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2594 uint num_workers = workers()->active_workers();
2595 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2596 workers()->run_task(&unlink_task);
2597 }
2598
2599 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2600 assert(obj != nullptr, "must not be null");
2601 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2602 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2603 // may falsely indicate that this is not the case here: however the collection set only
2604 // contains old regions when concurrent mark is not running.
2605 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2606 }
2607
2608 void G1CollectedHeap::make_pending_list_reachable() {
2609 if (collector_state()->in_concurrent_start_gc()) {
2610 oop pll_head = Universe::reference_pending_list();
2611 if (pll_head != nullptr) {
2612 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2613 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2614 }
2615 }
2616 }
2617
2618 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2619 _num_humongous_objects = num_humongous_total;
2620 _num_humongous_reclaim_candidates = num_humongous_candidates;
2621 }
2622
2623 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2624 const G1CollectionSetCandidates* candidates = collection_set()->candidates();
2625 return !candidates->is_empty();
2626 }
2627
2628 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2629 _collection_set_candidates_card_set_stats = stats;
2630 }
2631
2632 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2633 _young_gen_card_set_stats = stats;
2634 }
2635
2636 void G1CollectedHeap::record_obj_copy_mem_stats() {
2637 policy()->old_gen_alloc_tracker()->
2638 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2639
2640 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2641 create_g1_evac_summary(&_old_evac_stats));
2642 }
2643
2644 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2645 concurrent_mark()->clear_bitmap_for_region(hr);
2646 }
2647
2648 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2649 assert(!hr->is_free(), "the region should not be free");
2650 assert(!hr->is_empty(), "the region should not be empty");
2651 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2652
2653 // Reset region metadata to allow reuse.
2654 hr->hr_clear(true /* clear_space */);
2655 _policy->remset_tracker()->update_at_free(hr);
2656
2657 if (free_list != nullptr) {
2658 free_list->add_ordered(hr);
2659 }
2660 }
2661
2662 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2663 FreeRegionList* free_list) {
2664 assert(hr->is_humongous(), "this is only for humongous regions");
2665 hr->clear_humongous();
2666 free_region(hr, free_list);
2667 }
2668
2669 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2670 const uint humongous_regions_removed) {
2671 if (old_regions_removed > 0 || humongous_regions_removed > 0) {
2672 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2673 _old_set.bulk_remove(old_regions_removed);
2674 _humongous_set.bulk_remove(humongous_regions_removed);
2675 }
2676
2677 }
2678
2679 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2680 assert(list != nullptr, "list can't be null");
2681 if (!list->is_empty()) {
2682 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2683 _hrm.insert_list_into_free_list(list);
2684 }
2685 }
2686
2687 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2688 decrease_used(bytes);
2689 }
2690
2691 void G1CollectedHeap::clear_eden() {
2692 _eden.clear();
2693 }
2694
2695 void G1CollectedHeap::clear_collection_set() {
2696 collection_set()->clear();
2697 }
2698
2699 void G1CollectedHeap::rebuild_free_region_list() {
2700 Ticks start = Ticks::now();
2701 _hrm.rebuild_free_list(workers());
2702 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2703 }
2704
2705 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2706 public:
2707 virtual bool do_heap_region(HeapRegion* r) {
2708 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2709 G1CollectedHeap::heap()->clear_region_attr(r);
2710 r->clear_young_index_in_cset();
2711 return false;
2712 }
2713 };
2714
2715 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2716 G1AbandonCollectionSetClosure cl;
2717 collection_set_iterate_all(&cl);
2718
2719 collection_set->clear();
2720 collection_set->stop_incremental_building();
2721 }
2722
2723 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2724 return _allocator->is_retained_old_region(hr);
2725 }
2726
2727 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2728 _eden.add(hr);
2729 _policy->set_region_eden(hr);
2730 }
2731
2732 #ifdef ASSERT
2733
2734 class NoYoungRegionsClosure: public HeapRegionClosure {
2735 private:
2736 bool _success;
2737 public:
2738 NoYoungRegionsClosure() : _success(true) { }
2739 bool do_heap_region(HeapRegion* r) {
2740 if (r->is_young()) {
2741 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2742 p2i(r->bottom()), p2i(r->end()));
2743 _success = false;
2744 }
2745 return false;
2746 }
2747 bool success() { return _success; }
2748 };
2749
2750 bool G1CollectedHeap::check_young_list_empty() {
2751 bool ret = (young_regions_count() == 0);
2752
2753 NoYoungRegionsClosure closure;
2754 heap_region_iterate(&closure);
2755 ret = ret && closure.success();
2756
2757 return ret;
2758 }
2759
2760 #endif // ASSERT
2761
2762 // Remove the given HeapRegion from the appropriate region set.
2763 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2764 if (hr->is_humongous()) {
2765 _humongous_set.remove(hr);
2766 } else if (hr->is_old()) {
2767 _old_set.remove(hr);
2768 } else if (hr->is_young()) {
2769 // Note that emptying the eden and survivor lists is postponed and instead
2770 // done as the first step when rebuilding the regions sets again. The reason
2771 // for this is that during a full GC string deduplication needs to know if
2772 // a collected region was young or old when the full GC was initiated.
2773 hr->uninstall_surv_rate_group();
2774 } else {
2775 // We ignore free regions, we'll empty the free list afterwards.
2776 assert(hr->is_free(), "it cannot be another type");
2777 }
2778 }
2779
2780 void G1CollectedHeap::increase_used(size_t bytes) {
2781 _summary_bytes_used += bytes;
2782 }
2783
2784 void G1CollectedHeap::decrease_used(size_t bytes) {
2785 assert(_summary_bytes_used >= bytes,
2786 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2787 _summary_bytes_used, bytes);
2788 _summary_bytes_used -= bytes;
2789 }
2790
2791 void G1CollectedHeap::set_used(size_t bytes) {
2792 _summary_bytes_used = bytes;
2793 }
2794
2795 class RebuildRegionSetsClosure : public HeapRegionClosure {
2796 private:
2797 bool _free_list_only;
2798
2799 HeapRegionSet* _old_set;
2800 HeapRegionSet* _humongous_set;
2801
2802 HeapRegionManager* _hrm;
2803
2804 size_t _total_used;
2805
2806 public:
2807 RebuildRegionSetsClosure(bool free_list_only,
2808 HeapRegionSet* old_set,
2809 HeapRegionSet* humongous_set,
2810 HeapRegionManager* hrm) :
2811 _free_list_only(free_list_only), _old_set(old_set),
2812 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2813 assert(_hrm->num_free_regions() == 0, "pre-condition");
2814 if (!free_list_only) {
2815 assert(_old_set->is_empty(), "pre-condition");
2816 assert(_humongous_set->is_empty(), "pre-condition");
2817 }
2818 }
2819
2820 bool do_heap_region(HeapRegion* r) {
2821 if (r->is_empty()) {
2822 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2823 // Add free regions to the free list
2824 r->set_free();
2825 _hrm->insert_into_free_list(r);
2826 } else if (!_free_list_only) {
2827 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2828
2829 if (r->is_humongous()) {
2830 _humongous_set->add(r);
2831 } else {
2832 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2833 // We now move all (non-humongous, non-old) regions to old gen,
2834 // and register them as such.
2835 r->move_to_old();
2836 _old_set->add(r);
2837 }
2838 _total_used += r->used();
2839 }
2840
2841 return false;
2842 }
2843
2844 size_t total_used() {
2845 return _total_used;
2846 }
2847 };
2848
2849 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2850 assert_at_safepoint_on_vm_thread();
2851
2852 if (!free_list_only) {
2853 _eden.clear();
2854 _survivor.clear();
2855 }
2856
2857 RebuildRegionSetsClosure cl(free_list_only,
2858 &_old_set, &_humongous_set,
2859 &_hrm);
2860 heap_region_iterate(&cl);
2861
2862 if (!free_list_only) {
2863 set_used(cl.total_used());
2864 }
2865 assert_used_and_recalculate_used_equal(this);
2866 }
2867
2868 // Methods for the mutator alloc region
2869
2870 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
2871 bool force,
2872 uint node_index) {
2873 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2874 bool should_allocate = policy()->should_allocate_mutator_region();
2875 if (force || should_allocate) {
2876 HeapRegion* new_alloc_region = new_region(word_size,
2877 HeapRegionType::Eden,
2878 false /* do_expand */,
2879 node_index);
2880 if (new_alloc_region != nullptr) {
2881 set_region_short_lived_locked(new_alloc_region);
2882 _hr_printer.alloc(new_alloc_region, !should_allocate);
2883 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2884 return new_alloc_region;
2885 }
2886 }
2887 return nullptr;
2888 }
2889
2890 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
2891 size_t allocated_bytes) {
2892 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
2893 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
2894
2895 collection_set()->add_eden_region(alloc_region);
2896 increase_used(allocated_bytes);
2897 _eden.add_used_bytes(allocated_bytes);
2898 _hr_printer.retire(alloc_region);
2899
2900 // We update the eden sizes here, when the region is retired,
2901 // instead of when it's allocated, since this is the point that its
2902 // used space has been recorded in _summary_bytes_used.
2903 monitoring_support()->update_eden_size();
2904 }
2905
2906 // Methods for the GC alloc regions
2907
2908 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
2909 if (dest.is_old()) {
2910 return true;
2911 } else {
2912 return survivor_regions_count() < policy()->max_survivor_regions();
2913 }
2914 }
2915
2916 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
2917 assert(FreeList_lock->owned_by_self(), "pre-condition");
2918
2919 if (!has_more_regions(dest)) {
2920 return nullptr;
2921 }
2922
2923 HeapRegionType type;
2924 if (dest.is_young()) {
2925 type = HeapRegionType::Survivor;
2926 } else {
2927 type = HeapRegionType::Old;
2928 }
2929
2930 HeapRegion* new_alloc_region = new_region(word_size,
2931 type,
2932 true /* do_expand */,
2933 node_index);
2934
2935 if (new_alloc_region != nullptr) {
2936 if (type.is_survivor()) {
2937 new_alloc_region->set_survivor();
2938 _survivor.add(new_alloc_region);
2939 register_new_survivor_region_with_region_attr(new_alloc_region);
2940 } else {
2941 new_alloc_region->set_old();
2942 }
2943 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
2944 register_region_with_region_attr(new_alloc_region);
2945 _hr_printer.alloc(new_alloc_region);
2946 return new_alloc_region;
2947 }
2948 return nullptr;
2949 }
2950
2951 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
2952 size_t allocated_bytes,
2953 G1HeapRegionAttr dest) {
2954 _bytes_used_during_gc += allocated_bytes;
2955 if (dest.is_old()) {
2956 old_set_add(alloc_region);
2957 } else {
2958 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
2959 _survivor.add_used_bytes(allocated_bytes);
2960 }
2961
2962 bool const during_im = collector_state()->in_concurrent_start_gc();
2963 if (during_im && allocated_bytes > 0) {
2964 _cm->add_root_region(alloc_region);
2965 }
2966 _hr_printer.retire(alloc_region);
2967 }
2968
2969 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
2970 bool expanded = false;
2971 uint index = _hrm.find_highest_free(&expanded);
2972
2973 if (index != G1_NO_HRM_INDEX) {
2974 if (expanded) {
2975 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
2976 HeapRegion::GrainWords * HeapWordSize);
2977 }
2978 return _hrm.allocate_free_regions_starting_at(index, 1);
2979 }
2980 return nullptr;
2981 }
2982
2983 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
2984 assert(!_cm->is_marked_in_bitmap(obj), "must be");
2985
2986 _cm->raw_mark_in_bitmap(obj);
2987 if (collector_state()->in_concurrent_start_gc()) {
2988 _cm->add_to_liveness(worker_id, obj, obj_size);
2989 }
2990 }
2991
2992 // Optimized nmethod scanning
2993 class RegisterNMethodOopClosure: public OopClosure {
2994 G1CollectedHeap* _g1h;
2995 nmethod* _nm;
2996
2997 public:
2998 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
2999 _g1h(g1h), _nm(nm) {}
3000
3001 void do_oop(oop* p) {
3002 oop heap_oop = RawAccess<>::oop_load(p);
3003 if (!CompressedOops::is_null(heap_oop)) {
3004 oop obj = CompressedOops::decode_not_null(heap_oop);
3005 HeapRegion* hr = _g1h->heap_region_containing(obj);
3006 assert(!hr->is_continues_humongous(),
3007 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3008 " starting at " HR_FORMAT,
3009 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3010
3011 // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3012 hr->add_code_root_locked(_nm);
3013 }
3014 }
3015
3016 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3017 };
3018
3019 class UnregisterNMethodOopClosure: public OopClosure {
3020 G1CollectedHeap* _g1h;
3021 nmethod* _nm;
3022
3023 public:
3024 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3025 _g1h(g1h), _nm(nm) {}
3026
3027 void do_oop(oop* p) {
3028 oop heap_oop = RawAccess<>::oop_load(p);
3029 if (!CompressedOops::is_null(heap_oop)) {
3030 oop obj = CompressedOops::decode_not_null(heap_oop);
3031 HeapRegion* hr = _g1h->heap_region_containing(obj);
3032 assert(!hr->is_continues_humongous(),
3033 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3034 " starting at " HR_FORMAT,
3035 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3036
3037 hr->remove_code_root(_nm);
3038 }
3039 }
3040
3041 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3042 };
3043
3044 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3045 guarantee(nm != nullptr, "sanity");
3046 RegisterNMethodOopClosure reg_cl(this, nm);
3047 nm->oops_do(®_cl);
3048 }
3049
3050 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3051 guarantee(nm != nullptr, "sanity");
3052 UnregisterNMethodOopClosure reg_cl(this, nm);
3053 nm->oops_do(®_cl, true);
3054 }
3055
3056 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3057 if (evacuation_failed) {
3058 // Reset the G1EvacuationFailureALot counters and flags
3059 evac_failure_injector()->reset();
3060
3061 set_used(recalculate_used());
3062 } else {
3063 // The "used" of the collection set have already been subtracted
3064 // when they were freed. Add in the bytes used.
3065 increase_used(_bytes_used_during_gc);
3066 }
3067 }
3068
3069 class RebuildCodeRootClosure: public CodeBlobClosure {
3070 G1CollectedHeap* _g1h;
3071
3072 public:
3073 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3074 _g1h(g1h) {}
3075
3076 void do_code_blob(CodeBlob* cb) {
3077 nmethod* nm = cb->as_nmethod_or_null();
3078 if (nm != nullptr) {
3079 _g1h->register_nmethod(nm);
3080 }
3081 }
3082 };
3083
3084 void G1CollectedHeap::rebuild_code_roots() {
3085 RebuildCodeRootClosure blob_cl(this);
3086 CodeCache::blobs_do(&blob_cl);
3087 }
3088
3089 void G1CollectedHeap::initialize_serviceability() {
3090 _monitoring_support->initialize_serviceability();
3091 }
3092
3093 MemoryUsage G1CollectedHeap::memory_usage() {
3094 return _monitoring_support->memory_usage();
3095 }
3096
3097 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3098 return _monitoring_support->memory_managers();
3099 }
3100
3101 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3102 return _monitoring_support->memory_pools();
3103 }
3104
3105 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3106 HeapRegion* region = heap_region_containing(start);
3107 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3108 }
3109
3110 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3111 // We can reach here with an active code cache marking cycle either because the
3112 // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3113 // concurrent start young collection was below the threshold) or aborted. See
3114 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code
3115 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3116 // still have to arm all nmethod entry barriers. They are needed for adding oop
3117 // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3118 if (!CodeCache::is_gc_marking_cycle_active()) {
3119 CodeCache::on_gc_marking_cycle_start();
3120 }
3121 if (concurrent_mark_start) {
3122 CodeCache::arm_all_nmethods();
3123 }
3124 }
3125
3126 void G1CollectedHeap::finish_codecache_marking_cycle() {
3127 CodeCache::on_gc_marking_cycle_finish();
3128 CodeCache::arm_all_nmethods();
3129 }