1 /*
2 * Copyright (c) 2001, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/classLoaderDataGraph.hpp"
27 #include "classfile/metadataOnStackMark.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "compiler/oopMap.hpp"
32 #include "gc/g1/g1Allocator.inline.hpp"
33 #include "gc/g1/g1Arguments.hpp"
34 #include "gc/g1/g1BarrierSet.hpp"
35 #include "gc/g1/g1BatchedTask.hpp"
36 #include "gc/g1/g1CollectedHeap.inline.hpp"
37 #include "gc/g1/g1CollectionSet.hpp"
38 #include "gc/g1/g1CollectionSetCandidates.hpp"
39 #include "gc/g1/g1CollectorState.hpp"
40 #include "gc/g1/g1ConcurrentRefine.hpp"
41 #include "gc/g1/g1ConcurrentRefineThread.hpp"
42 #include "gc/g1/g1ConcurrentMarkThread.inline.hpp"
43 #include "gc/g1/g1DirtyCardQueue.hpp"
44 #include "gc/g1/g1EvacStats.inline.hpp"
45 #include "gc/g1/g1FullCollector.hpp"
46 #include "gc/g1/g1GCCounters.hpp"
47 #include "gc/g1/g1GCParPhaseTimesTracker.hpp"
48 #include "gc/g1/g1GCPhaseTimes.hpp"
49 #include "gc/g1/g1GCPauseType.hpp"
50 #include "gc/g1/g1HeapSizingPolicy.hpp"
51 #include "gc/g1/g1HeapTransition.hpp"
52 #include "gc/g1/g1HeapVerifier.hpp"
53 #include "gc/g1/g1InitLogger.hpp"
54 #include "gc/g1/g1MemoryPool.hpp"
55 #include "gc/g1/g1MonotonicArenaFreeMemoryTask.hpp"
56 #include "gc/g1/g1OopClosures.inline.hpp"
57 #include "gc/g1/g1ParallelCleaning.hpp"
58 #include "gc/g1/g1ParScanThreadState.inline.hpp"
59 #include "gc/g1/g1PeriodicGCTask.hpp"
60 #include "gc/g1/g1Policy.hpp"
61 #include "gc/g1/g1RedirtyCardsQueue.hpp"
62 #include "gc/g1/g1RegionToSpaceMapper.hpp"
63 #include "gc/g1/g1RemSet.hpp"
64 #include "gc/g1/g1RootClosures.hpp"
65 #include "gc/g1/g1RootProcessor.hpp"
66 #include "gc/g1/g1SATBMarkQueueSet.hpp"
67 #include "gc/g1/g1ServiceThread.hpp"
68 #include "gc/g1/g1ThreadLocalData.hpp"
69 #include "gc/g1/g1Trace.hpp"
70 #include "gc/g1/g1UncommitRegionTask.hpp"
71 #include "gc/g1/g1VMOperations.hpp"
72 #include "gc/g1/g1YoungCollector.hpp"
73 #include "gc/g1/g1YoungGCEvacFailureInjector.hpp"
74 #include "gc/g1/heapRegion.inline.hpp"
75 #include "gc/g1/heapRegionRemSet.inline.hpp"
76 #include "gc/g1/heapRegionSet.inline.hpp"
77 #include "gc/shared/concurrentGCBreakpoints.hpp"
78 #include "gc/shared/gcBehaviours.hpp"
79 #include "gc/shared/gcHeapSummary.hpp"
80 #include "gc/shared/gcId.hpp"
81 #include "gc/shared/gcLocker.inline.hpp"
82 #include "gc/shared/gcTimer.hpp"
83 #include "gc/shared/gcTraceTime.inline.hpp"
84 #include "gc/shared/generationSpec.hpp"
85 #include "gc/shared/isGCActiveMark.hpp"
86 #include "gc/shared/locationPrinter.inline.hpp"
87 #include "gc/shared/oopStorageParState.hpp"
88 #include "gc/shared/preservedMarks.inline.hpp"
89 #include "gc/shared/referenceProcessor.inline.hpp"
90 #include "gc/shared/suspendibleThreadSet.hpp"
91 #include "gc/shared/taskqueue.inline.hpp"
92 #include "gc/shared/taskTerminator.hpp"
93 #include "gc/shared/tlab_globals.hpp"
94 #include "gc/shared/workerPolicy.hpp"
95 #include "gc/shared/weakProcessor.inline.hpp"
96 #include "logging/log.hpp"
97 #include "memory/allocation.hpp"
98 #include "memory/heapInspection.hpp"
99 #include "memory/iterator.hpp"
100 #include "memory/metaspaceUtils.hpp"
101 #include "memory/resourceArea.hpp"
102 #include "memory/universe.hpp"
103 #include "oops/access.inline.hpp"
104 #include "oops/compressedOops.inline.hpp"
105 #include "oops/oop.inline.hpp"
106 #include "runtime/atomic.hpp"
107 #include "runtime/handles.inline.hpp"
108 #include "runtime/init.hpp"
109 #include "runtime/java.hpp"
110 #include "runtime/orderAccess.hpp"
111 #include "runtime/threadSMR.hpp"
112 #include "runtime/vmThread.hpp"
113 #include "utilities/align.hpp"
114 #include "utilities/autoRestore.hpp"
115 #include "utilities/bitMap.inline.hpp"
116 #include "utilities/globalDefinitions.hpp"
117 #include "utilities/stack.inline.hpp"
118
119 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
120
121 // INVARIANTS/NOTES
122 //
123 // All allocation activity covered by the G1CollectedHeap interface is
124 // serialized by acquiring the HeapLock. This happens in mem_allocate
125 // and allocate_new_tlab, which are the "entry" points to the
126 // allocation code from the rest of the JVM. (Note that this does not
127 // apply to TLAB allocation, which is not part of this interface: it
128 // is done by clients of this interface.)
129
130 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
131 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
132 }
133
134 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
135 // The from card cache is not the memory that is actually committed. So we cannot
136 // take advantage of the zero_filled parameter.
137 reset_from_card_cache(start_idx, num_regions);
138 }
139
140 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
141 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
142 cl->set_max_workers(num_workers);
143 workers()->run_task(cl, num_workers);
144 }
145
146 uint G1CollectedHeap::get_chunks_per_region() {
147 uint log_region_size = HeapRegion::LogOfHRGrainBytes;
148 // Limit the expected input values to current known possible values of the
149 // (log) region size. Adjust as necessary after testing if changing the permissible
150 // values for region size.
151 assert(log_region_size >= 20 && log_region_size <= 29,
152 "expected value in [20,29], but got %u", log_region_size);
153 return 1u << (log_region_size / 2 - 4);
154 }
155
156 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
157 MemRegion mr) {
158 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
159 }
160
161 // Private methods.
162
163 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
164 HeapRegionType type,
165 bool do_expand,
166 uint node_index) {
167 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
168 "the only time we use this to allocate a humongous region is "
169 "when we are allocating a single humongous region");
170
171 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
172
173 if (res == NULL && 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 HeapWord*
197 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
198 uint num_regions,
199 size_t word_size) {
200 assert(first_hr != NULL, "pre-condition");
201 assert(is_humongous(word_size), "word_size should be humongous");
202 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
203
204 // Index of last region in the series.
205 uint first = first_hr->hrm_index();
206 uint last = first + num_regions - 1;
207
208 // We need to initialize the region(s) we just discovered. This is
209 // a bit tricky given that it can happen concurrently with
210 // refinement threads refining cards on these regions and
211 // potentially wanting to refine the BOT as they are scanning
212 // those cards (this can happen shortly after a cleanup; see CR
213 // 6991377). So we have to set up the region(s) carefully and in
214 // a specific order.
215
216 // The word size sum of all the regions we will allocate.
217 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
218 assert(word_size <= word_size_sum, "sanity");
219
220 // The passed in hr will be the "starts humongous" region. The header
221 // of the new object will be placed at the bottom of this region.
222 HeapWord* new_obj = first_hr->bottom();
223 // This will be the new top of the new object.
224 HeapWord* obj_top = new_obj + word_size;
225
226 // First, we need to zero the header of the space that we will be
227 // allocating. When we update top further down, some refinement
228 // threads might try to scan the region. By zeroing the header we
229 // ensure that any thread that will try to scan the region will
230 // come across the zero klass word and bail out.
231 //
232 // NOTE: It would not have been correct to have used
233 // CollectedHeap::fill_with_object() and make the space look like
234 // an int array. The thread that is doing the allocation will
235 // later update the object header to a potentially different array
236 // type and, for a very short period of time, the klass and length
237 // fields will be inconsistent. This could cause a refinement
238 // thread to calculate the object size incorrectly.
239 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
240
241 // Next, pad out the unused tail of the last region with filler
242 // objects, for improved usage accounting.
243 // How many words we use for filler objects.
244 size_t word_fill_size = word_size_sum - word_size;
245
246 // How many words memory we "waste" which cannot hold a filler object.
247 size_t words_not_fillable = 0;
248
249 if (word_fill_size >= min_fill_size()) {
250 fill_with_objects(obj_top, word_fill_size);
251 } else if (word_fill_size > 0) {
252 // We have space to fill, but we cannot fit an object there.
253 words_not_fillable = word_fill_size;
254 word_fill_size = 0;
255 }
256
257 // We will set up the first region as "starts humongous". This
258 // will also update the BOT covering all the regions to reflect
259 // that there is a single object that starts at the bottom of the
260 // first region.
261 first_hr->set_starts_humongous(obj_top, word_fill_size);
262 _policy->remset_tracker()->update_at_allocate(first_hr);
263 // Then, if there are any, we will set up the "continues
264 // humongous" regions.
265 HeapRegion* hr = NULL;
266 for (uint i = first + 1; i <= last; ++i) {
267 hr = region_at(i);
268 hr->set_continues_humongous(first_hr);
269 _policy->remset_tracker()->update_at_allocate(hr);
270 }
271
272 // Up to this point no concurrent thread would have been able to
273 // do any scanning on any region in this series. All the top
274 // fields still point to bottom, so the intersection between
275 // [bottom,top] and [card_start,card_end] will be empty. Before we
276 // update the top fields, we'll do a storestore to make sure that
277 // no thread sees the update to top before the zeroing of the
278 // object header and the BOT initialization.
279 OrderAccess::storestore();
280
281 // Now, we will update the top fields of the "continues humongous"
282 // regions except the last one.
283 for (uint i = first; i < last; ++i) {
284 hr = region_at(i);
285 hr->set_top(hr->end());
286 }
287
288 hr = region_at(last);
289 // If we cannot fit a filler object, we must set top to the end
290 // of the humongous object, otherwise we cannot iterate the heap
291 // and the BOT will not be complete.
292 hr->set_top(hr->end() - words_not_fillable);
293
294 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
295 "obj_top should be in last region");
296
297 assert(words_not_fillable == 0 ||
298 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
299 "Miscalculation in humongous allocation");
300
301 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
302
303 for (uint i = first; i <= last; ++i) {
304 hr = region_at(i);
305 _humongous_set.add(hr);
306 _hr_printer.alloc(hr);
307 }
308
309 return new_obj;
310 }
311
312 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
313 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
314 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
315 }
316
317 // If could fit into free regions w/o expansion, try.
318 // Otherwise, if can expand, do so.
319 // Otherwise, if using ex regions might help, try with ex given back.
320 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
321 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
322
323 _verifier->verify_region_sets_optional();
324
325 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
326
327 // Policy: First try to allocate a humongous object in the free list.
328 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
329 if (humongous_start == NULL) {
330 // Policy: We could not find enough regions for the humongous object in the
331 // free list. Look through the heap to find a mix of free and uncommitted regions.
332 // If so, expand the heap and allocate the humongous object.
333 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
334 if (humongous_start != NULL) {
335 // We managed to find a region by expanding the heap.
336 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
337 word_size * HeapWordSize);
338 policy()->record_new_heap_size(num_regions());
339 } else {
340 // Policy: Potentially trigger a defragmentation GC.
341 }
342 }
343
344 HeapWord* result = NULL;
345 if (humongous_start != NULL) {
346 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
347 assert(result != NULL, "it should always return a valid result");
348
349 // A successful humongous object allocation changes the used space
350 // information of the old generation so we need to recalculate the
351 // sizes and update the jstat counters here.
352 monitoring_support()->update_sizes();
353 }
354
355 _verifier->verify_region_sets_optional();
356
357 return result;
358 }
359
360 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
361 size_t requested_size,
362 size_t* actual_size) {
363 assert_heap_not_locked_and_not_at_safepoint();
364 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
365
366 return attempt_allocation(min_size, requested_size, actual_size);
367 }
368
369 HeapWord*
370 G1CollectedHeap::mem_allocate(size_t word_size,
371 bool* gc_overhead_limit_was_exceeded) {
372 assert_heap_not_locked_and_not_at_safepoint();
373
374 if (is_humongous(word_size)) {
375 return attempt_allocation_humongous(word_size);
376 }
377 size_t dummy = 0;
378 return attempt_allocation(word_size, word_size, &dummy);
379 }
380
381 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
382 ResourceMark rm; // For retrieving the thread names in log messages.
383
384 // Make sure you read the note in attempt_allocation_humongous().
385
386 assert_heap_not_locked_and_not_at_safepoint();
387 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
388 "be called for humongous allocation requests");
389
390 // We should only get here after the first-level allocation attempt
391 // (attempt_allocation()) failed to allocate.
392
393 // We will loop until a) we manage to successfully perform the
394 // allocation or b) we successfully schedule a collection which
395 // fails to perform the allocation. b) is the only case when we'll
396 // return NULL.
397 HeapWord* result = NULL;
398 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
399 bool should_try_gc;
400 uint gc_count_before;
401
402 {
403 MutexLocker x(Heap_lock);
404
405 // Now that we have the lock, we first retry the allocation in case another
406 // thread changed the region while we were waiting to acquire the lock.
407 result = _allocator->attempt_allocation_locked(word_size);
408 if (result != NULL) {
409 return result;
410 }
411
412 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
413 // This is different to when only GCLocker::needs_gc() is set: try to avoid
414 // waiting because the GCLocker is active to not wait too long.
415 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
416 // No need for an ergo message here, can_expand_young_list() does this when
417 // it returns true.
418 result = _allocator->attempt_allocation_force(word_size);
419 if (result != NULL) {
420 return result;
421 }
422 }
423
424 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
425 // the GCLocker initiated GC has been performed and then retry. This includes
426 // the case when the GC Locker is not active but has not been performed.
427 should_try_gc = !GCLocker::needs_gc();
428 // Read the GC count while still holding the Heap_lock.
429 gc_count_before = total_collections();
430 }
431
432 if (should_try_gc) {
433 bool succeeded;
434 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause);
435 if (result != NULL) {
436 assert(succeeded, "only way to get back a non-NULL result");
437 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
438 Thread::current()->name(), p2i(result));
439 return result;
440 }
441
442 if (succeeded) {
443 // We successfully scheduled a collection which failed to allocate. No
444 // point in trying to allocate further. We'll just return NULL.
445 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
446 SIZE_FORMAT " words", Thread::current()->name(), word_size);
447 return NULL;
448 }
449 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
450 Thread::current()->name(), word_size);
451 } else {
452 // Failed to schedule a collection.
453 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
454 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
455 SIZE_FORMAT " words", Thread::current()->name(), word_size);
456 return NULL;
457 }
458 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
459 // The GCLocker is either active or the GCLocker initiated
460 // GC has not yet been performed. Stall until it is and
461 // then retry the allocation.
462 GCLocker::stall_until_clear();
463 gclocker_retry_count += 1;
464 }
465
466 // We can reach here if we were unsuccessful in scheduling a
467 // collection (because another thread beat us to it) or if we were
468 // stalled due to the GC locker. In either can we should retry the
469 // allocation attempt in case another thread successfully
470 // performed a collection and reclaimed enough space. We do the
471 // first attempt (without holding the Heap_lock) here and the
472 // follow-on attempt will be at the start of the next loop
473 // iteration (after taking the Heap_lock).
474 size_t dummy = 0;
475 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
476 if (result != NULL) {
477 return result;
478 }
479
480 // Give a warning if we seem to be looping forever.
481 if ((QueuedAllocationWarningCount > 0) &&
482 (try_count % QueuedAllocationWarningCount == 0)) {
483 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
484 Thread::current()->name(), try_count, word_size);
485 }
486 }
487
488 ShouldNotReachHere();
489 return NULL;
490 }
491
492 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
493 assert(ranges != NULL, "MemRegion array NULL");
494 assert(count != 0, "No MemRegions provided");
495 MemRegion reserved = _hrm.reserved();
496 for (size_t i = 0; i < count; i++) {
497 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
498 return false;
499 }
500 }
501 return true;
502 }
503
504 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
505 size_t count,
506 bool open) {
507 assert(!is_init_completed(), "Expect to be called at JVM init time");
508 assert(ranges != NULL, "MemRegion array NULL");
509 assert(count != 0, "No MemRegions provided");
510 MutexLocker x(Heap_lock);
511
512 MemRegion reserved = _hrm.reserved();
513 HeapWord* prev_last_addr = NULL;
514 HeapRegion* prev_last_region = NULL;
515
516 // Temporarily disable pretouching of heap pages. This interface is used
517 // when mmap'ing archived heap data in, so pre-touching is wasted.
518 FlagSetting fs(AlwaysPreTouch, false);
519
520 // For each specified MemRegion range, allocate the corresponding G1
521 // regions and mark them as archive regions. We expect the ranges
522 // in ascending starting address order, without overlap.
523 for (size_t i = 0; i < count; i++) {
524 MemRegion curr_range = ranges[i];
525 HeapWord* start_address = curr_range.start();
526 size_t word_size = curr_range.word_size();
527 HeapWord* last_address = curr_range.last();
528 size_t commits = 0;
529
530 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
531 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
532 p2i(start_address), p2i(last_address));
533 guarantee(start_address > prev_last_addr,
534 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
535 p2i(start_address), p2i(prev_last_addr));
536 prev_last_addr = last_address;
537
538 // Check for ranges that start in the same G1 region in which the previous
539 // range ended, and adjust the start address so we don't try to allocate
540 // the same region again. If the current range is entirely within that
541 // region, skip it, just adjusting the recorded top.
542 HeapRegion* start_region = _hrm.addr_to_region(start_address);
543 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
544 start_address = start_region->end();
545 if (start_address > last_address) {
546 increase_used(word_size * HeapWordSize);
547 start_region->set_top(last_address + 1);
548 continue;
549 }
550 start_region->set_top(start_address);
551 curr_range = MemRegion(start_address, last_address + 1);
552 start_region = _hrm.addr_to_region(start_address);
553 }
554
555 // Perform the actual region allocation, exiting if it fails.
556 // Then note how much new space we have allocated.
557 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
558 return false;
559 }
560 increase_used(word_size * HeapWordSize);
561 if (commits != 0) {
562 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
563 HeapRegion::GrainWords * HeapWordSize * commits);
564
565 }
566
567 // Mark each G1 region touched by the range as archive, add it to
568 // the old set, and set top.
569 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
570 HeapRegion* last_region = _hrm.addr_to_region(last_address);
571 prev_last_region = last_region;
572
573 while (curr_region != NULL) {
574 assert(curr_region->is_empty() && !curr_region->is_pinned(),
575 "Region already in use (index %u)", curr_region->hrm_index());
576 if (open) {
577 curr_region->set_open_archive();
578 } else {
579 curr_region->set_closed_archive();
580 }
581 _hr_printer.alloc(curr_region);
582 _archive_set.add(curr_region);
583 HeapWord* top;
584 HeapRegion* next_region;
585 if (curr_region != last_region) {
586 top = curr_region->end();
587 next_region = _hrm.next_region_in_heap(curr_region);
588 } else {
589 top = last_address + 1;
590 next_region = NULL;
591 }
592 curr_region->set_top(top);
593 curr_region = next_region;
594 }
595 }
596 return true;
597 }
598
599 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
600 assert(!is_init_completed(), "Expect to be called at JVM init time");
601 assert(ranges != NULL, "MemRegion array NULL");
602 assert(count != 0, "No MemRegions provided");
603 MemRegion reserved = _hrm.reserved();
604 HeapWord *prev_last_addr = NULL;
605 HeapRegion* prev_last_region = NULL;
606
607 // For each MemRegion, create filler objects, if needed, in the G1 regions
608 // that contain the address range. The address range actually within the
609 // MemRegion will not be modified. That is assumed to have been initialized
610 // elsewhere, probably via an mmap of archived heap data.
611 MutexLocker x(Heap_lock);
612 for (size_t i = 0; i < count; i++) {
613 HeapWord* start_address = ranges[i].start();
614 HeapWord* last_address = ranges[i].last();
615
616 assert(reserved.contains(start_address) && reserved.contains(last_address),
617 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
618 p2i(start_address), p2i(last_address));
619 assert(start_address > prev_last_addr,
620 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
621 p2i(start_address), p2i(prev_last_addr));
622
623 HeapRegion* start_region = _hrm.addr_to_region(start_address);
624 HeapRegion* last_region = _hrm.addr_to_region(last_address);
625 HeapWord* bottom_address = start_region->bottom();
626
627 // Check for a range beginning in the same region in which the
628 // previous one ended.
629 if (start_region == prev_last_region) {
630 bottom_address = prev_last_addr + 1;
631 }
632
633 // Verify that the regions were all marked as archive regions by
634 // alloc_archive_regions.
635 HeapRegion* curr_region = start_region;
636 while (curr_region != NULL) {
637 guarantee(curr_region->is_archive(),
638 "Expected archive region at index %u", curr_region->hrm_index());
639 if (curr_region != last_region) {
640 curr_region = _hrm.next_region_in_heap(curr_region);
641 } else {
642 curr_region = NULL;
643 }
644 }
645
646 prev_last_addr = last_address;
647 prev_last_region = last_region;
648
649 // Fill the memory below the allocated range with dummy object(s),
650 // if the region bottom does not match the range start, or if the previous
651 // range ended within the same G1 region, and there is a gap.
652 assert(start_address >= bottom_address, "bottom address should not be greater than start address");
653 if (start_address > bottom_address) {
654 size_t fill_size = pointer_delta(start_address, bottom_address);
655 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
656 increase_used(fill_size * HeapWordSize);
657 }
658 }
659 }
660
661 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
662 size_t desired_word_size,
663 size_t* actual_word_size) {
664 assert_heap_not_locked_and_not_at_safepoint();
665 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
666 "be called for humongous allocation requests");
667
668 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
669
670 if (result == NULL) {
671 *actual_word_size = desired_word_size;
672 result = attempt_allocation_slow(desired_word_size);
673 }
674
675 assert_heap_not_locked();
676 if (result != NULL) {
677 assert(*actual_word_size != 0, "Actual size must have been set here");
678 dirty_young_block(result, *actual_word_size);
679 } else {
680 *actual_word_size = 0;
681 }
682
683 return result;
684 }
685
686 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion* ranges, size_t count) {
687 assert(!is_init_completed(), "Expect to be called at JVM init time");
688 assert(ranges != NULL, "MemRegion array NULL");
689 assert(count != 0, "No MemRegions provided");
690
691 HeapWord* st = ranges[0].start();
692 HeapWord* last = ranges[count-1].last();
693 HeapRegion* hr_st = _hrm.addr_to_region(st);
694 HeapRegion* hr_last = _hrm.addr_to_region(last);
695
696 HeapRegion* hr_curr = hr_st;
697 while (hr_curr != NULL) {
698 hr_curr->update_bot();
699 if (hr_curr != hr_last) {
700 hr_curr = _hrm.next_region_in_heap(hr_curr);
701 } else {
702 hr_curr = NULL;
703 }
704 }
705 }
706
707 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
708 assert(!is_init_completed(), "Expect to be called at JVM init time");
709 assert(ranges != NULL, "MemRegion array NULL");
710 assert(count != 0, "No MemRegions provided");
711 MemRegion reserved = _hrm.reserved();
712 HeapWord* prev_last_addr = NULL;
713 HeapRegion* prev_last_region = NULL;
714 size_t size_used = 0;
715 uint shrink_count = 0;
716
717 // For each Memregion, free the G1 regions that constitute it, and
718 // notify mark-sweep that the range is no longer to be considered 'archive.'
719 MutexLocker x(Heap_lock);
720 for (size_t i = 0; i < count; i++) {
721 HeapWord* start_address = ranges[i].start();
722 HeapWord* last_address = ranges[i].last();
723
724 assert(reserved.contains(start_address) && reserved.contains(last_address),
725 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
726 p2i(start_address), p2i(last_address));
727 assert(start_address > prev_last_addr,
728 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
729 p2i(start_address), p2i(prev_last_addr));
730 size_used += ranges[i].byte_size();
731 prev_last_addr = last_address;
732
733 HeapRegion* start_region = _hrm.addr_to_region(start_address);
734 HeapRegion* last_region = _hrm.addr_to_region(last_address);
735
736 // Check for ranges that start in the same G1 region in which the previous
737 // range ended, and adjust the start address so we don't try to free
738 // the same region again. If the current range is entirely within that
739 // region, skip it.
740 if (start_region == prev_last_region) {
741 start_address = start_region->end();
742 if (start_address > last_address) {
743 continue;
744 }
745 start_region = _hrm.addr_to_region(start_address);
746 }
747 prev_last_region = last_region;
748
749 // After verifying that each region was marked as an archive region by
750 // alloc_archive_regions, set it free and empty and uncommit it.
751 HeapRegion* curr_region = start_region;
752 while (curr_region != NULL) {
753 guarantee(curr_region->is_archive(),
754 "Expected archive region at index %u", curr_region->hrm_index());
755 uint curr_index = curr_region->hrm_index();
756 _archive_set.remove(curr_region);
757 curr_region->set_free();
758 curr_region->set_top(curr_region->bottom());
759 if (curr_region != last_region) {
760 curr_region = _hrm.next_region_in_heap(curr_region);
761 } else {
762 curr_region = NULL;
763 }
764
765 _hrm.shrink_at(curr_index, 1);
766 shrink_count++;
767 }
768 }
769
770 if (shrink_count != 0) {
771 log_debug(gc, ergo, heap)("Attempt heap shrinking (archive regions). Total size: " SIZE_FORMAT "B",
772 HeapRegion::GrainWords * HeapWordSize * shrink_count);
773 // Explicit uncommit.
774 uncommit_regions(shrink_count);
775 }
776 decrease_used(size_used);
777 }
778
779 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
780 ResourceMark rm; // For retrieving the thread names in log messages.
781
782 // The structure of this method has a lot of similarities to
783 // attempt_allocation_slow(). The reason these two were not merged
784 // into a single one is that such a method would require several "if
785 // allocation is not humongous do this, otherwise do that"
786 // conditional paths which would obscure its flow. In fact, an early
787 // version of this code did use a unified method which was harder to
788 // follow and, as a result, it had subtle bugs that were hard to
789 // track down. So keeping these two methods separate allows each to
790 // be more readable. It will be good to keep these two in sync as
791 // much as possible.
792
793 assert_heap_not_locked_and_not_at_safepoint();
794 assert(is_humongous(word_size), "attempt_allocation_humongous() "
795 "should only be called for humongous allocations");
796
797 // Humongous objects can exhaust the heap quickly, so we should check if we
798 // need to start a marking cycle at each humongous object allocation. We do
799 // the check before we do the actual allocation. The reason for doing it
800 // before the allocation is that we avoid having to keep track of the newly
801 // allocated memory while we do a GC.
802 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
803 word_size)) {
804 collect(GCCause::_g1_humongous_allocation);
805 }
806
807 // We will loop until a) we manage to successfully perform the
808 // allocation or b) we successfully schedule a collection which
809 // fails to perform the allocation. b) is the only case when we'll
810 // return NULL.
811 HeapWord* result = NULL;
812 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
813 bool should_try_gc;
814 uint gc_count_before;
815
816
817 {
818 MutexLocker x(Heap_lock);
819
820 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
821 // Given that humongous objects are not allocated in young
822 // regions, we'll first try to do the allocation without doing a
823 // collection hoping that there's enough space in the heap.
824 result = humongous_obj_allocate(word_size);
825 if (result != NULL) {
826 policy()->old_gen_alloc_tracker()->
827 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
828 return result;
829 }
830
831 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
832 // the GCLocker initiated GC has been performed and then retry. This includes
833 // the case when the GC Locker is not active but has not been performed.
834 should_try_gc = !GCLocker::needs_gc();
835 // Read the GC count while still holding the Heap_lock.
836 gc_count_before = total_collections();
837 }
838
839 if (should_try_gc) {
840 bool succeeded;
841 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
842 if (result != NULL) {
843 assert(succeeded, "only way to get back a non-NULL result");
844 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
845 Thread::current()->name(), p2i(result));
846 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
847 policy()->old_gen_alloc_tracker()->
848 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
849 return result;
850 }
851
852 if (succeeded) {
853 // We successfully scheduled a collection which failed to allocate. No
854 // point in trying to allocate further. We'll just return NULL.
855 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
856 SIZE_FORMAT " words", Thread::current()->name(), word_size);
857 return NULL;
858 }
859 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
860 Thread::current()->name(), word_size);
861 } else {
862 // Failed to schedule a collection.
863 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
864 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
865 SIZE_FORMAT " words", Thread::current()->name(), word_size);
866 return NULL;
867 }
868 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
869 // The GCLocker is either active or the GCLocker initiated
870 // GC has not yet been performed. Stall until it is and
871 // then retry the allocation.
872 GCLocker::stall_until_clear();
873 gclocker_retry_count += 1;
874 }
875
876
877 // We can reach here if we were unsuccessful in scheduling a
878 // collection (because another thread beat us to it) or if we were
879 // stalled due to the GC locker. In either can we should retry the
880 // allocation attempt in case another thread successfully
881 // performed a collection and reclaimed enough space.
882 // Humongous object allocation always needs a lock, so we wait for the retry
883 // in the next iteration of the loop, unlike for the regular iteration case.
884 // Give a warning if we seem to be looping forever.
885
886 if ((QueuedAllocationWarningCount > 0) &&
887 (try_count % QueuedAllocationWarningCount == 0)) {
888 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
889 Thread::current()->name(), try_count, word_size);
890 }
891 }
892
893 ShouldNotReachHere();
894 return NULL;
895 }
896
897 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
898 bool expect_null_mutator_alloc_region) {
899 assert_at_safepoint_on_vm_thread();
900 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
901 "the current alloc region was unexpectedly found to be non-NULL");
902
903 if (!is_humongous(word_size)) {
904 return _allocator->attempt_allocation_locked(word_size);
905 } else {
906 HeapWord* result = humongous_obj_allocate(word_size);
907 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
908 collector_state()->set_initiate_conc_mark_if_possible(true);
909 }
910 return result;
911 }
912
913 ShouldNotReachHere();
914 }
915
916 class PostCompactionPrinterClosure: public HeapRegionClosure {
917 private:
918 G1HRPrinter* _hr_printer;
919 public:
920 bool do_heap_region(HeapRegion* hr) {
921 assert(!hr->is_young(), "not expecting to find young regions");
922 _hr_printer->post_compaction(hr);
923 return false;
924 }
925
926 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
927 : _hr_printer(hr_printer) { }
928 };
929
930 void G1CollectedHeap::print_heap_after_full_collection() {
931 // Post collection region logging.
932 // We should do this after we potentially resize the heap so
933 // that all the COMMIT / UNCOMMIT events are generated before
934 // the compaction events.
935 if (_hr_printer.is_active()) {
936 PostCompactionPrinterClosure cl(hr_printer());
937 heap_region_iterate(&cl);
938 }
939 }
940
941 bool G1CollectedHeap::abort_concurrent_cycle() {
942 // Disable discovery and empty the discovered lists
943 // for the CM ref processor.
944 _ref_processor_cm->disable_discovery();
945 _ref_processor_cm->abandon_partial_discovery();
946 _ref_processor_cm->verify_no_references_recorded();
947
948 // Abandon current iterations of concurrent marking and concurrent
949 // refinement, if any are in progress.
950 return concurrent_mark()->concurrent_cycle_abort();
951 }
952
953 void G1CollectedHeap::prepare_heap_for_full_collection() {
954 // Make sure we'll choose a new allocation region afterwards.
955 _allocator->release_mutator_alloc_regions();
956 _allocator->abandon_gc_alloc_regions();
957
958 // We may have added regions to the current incremental collection
959 // set between the last GC or pause and now. We need to clear the
960 // incremental collection set and then start rebuilding it afresh
961 // after this full GC.
962 abandon_collection_set(collection_set());
963
964 _hrm.remove_all_free_regions();
965 }
966
967 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
968 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
969 assert_used_and_recalculate_used_equal(this);
970 if (!VerifyBeforeGC) {
971 return;
972 }
973 _verifier->verify_region_sets_optional();
974 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
975 _verifier->verify_bitmap_clear(true /* above_tams_only */);
976 }
977
978 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
979 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
980 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
981 DEBUG_ONLY(MetaspaceUtils::verify();)
982
983 // Prepare heap for normal collections.
984 assert(num_free_regions() == 0, "we should not have added any free regions");
985 rebuild_region_sets(false /* free_list_only */);
986 abort_refinement();
987 resize_heap_if_necessary();
988 uncommit_regions_if_necessary();
989
990 // Rebuild the code root lists for each region
991 rebuild_code_roots();
992
993 start_new_collection_set();
994 _allocator->init_mutator_alloc_regions();
995
996 // Post collection state updates.
997 MetaspaceGC::compute_new_size();
998 }
999
1000 void G1CollectedHeap::abort_refinement() {
1001 // Discard all remembered set updates and reset refinement statistics.
1002 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
1003 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1004 "DCQS should be empty");
1005 concurrent_refine()->get_and_reset_refinement_stats();
1006 }
1007
1008 void G1CollectedHeap::verify_after_full_collection() {
1009 if (!VerifyAfterGC) {
1010 return;
1011 }
1012 _hrm.verify_optional();
1013 _verifier->verify_region_sets_optional();
1014 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1015 _verifier->verify_bitmap_clear(false /* above_tams_only */);
1016
1017 // At this point there should be no regions in the
1018 // entire heap tagged as young.
1019 assert(check_young_list_empty(), "young list should be empty at this point");
1020
1021 // Note: since we've just done a full GC, concurrent
1022 // marking is no longer active. Therefore we need not
1023 // re-enable reference discovery for the CM ref processor.
1024 // That will be done at the start of the next marking cycle.
1025 // We also know that the STW processor should no longer
1026 // discover any new references.
1027 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1028 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1029 _ref_processor_stw->verify_no_references_recorded();
1030 _ref_processor_cm->verify_no_references_recorded();
1031 }
1032
1033 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1034 bool clear_all_soft_refs,
1035 bool do_maximal_compaction) {
1036 assert_at_safepoint_on_vm_thread();
1037
1038 if (GCLocker::check_active_before_gc()) {
1039 // Full GC was not completed.
1040 return false;
1041 }
1042
1043 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1044 soft_ref_policy()->should_clear_all_soft_refs();
1045
1046 G1FullGCMark gc_mark;
1047 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1048 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
1049
1050 collector.prepare_collection();
1051 collector.collect();
1052 collector.complete_collection();
1053
1054 // Full collection was successfully completed.
1055 return true;
1056 }
1057
1058 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1059 // Currently, there is no facility in the do_full_collection(bool) API to notify
1060 // the caller that the collection did not succeed (e.g., because it was locked
1061 // out by the GC locker). So, right now, we'll ignore the return value.
1062 // When clear_all_soft_refs is set we want to do a maximal compaction
1063 // not leaving any dead wood.
1064 bool do_maximal_compaction = clear_all_soft_refs;
1065 bool dummy = do_full_collection(true, /* explicit_gc */
1066 clear_all_soft_refs,
1067 do_maximal_compaction);
1068 }
1069
1070 bool G1CollectedHeap::upgrade_to_full_collection() {
1071 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1072 log_info(gc, ergo)("Attempting full compaction clearing soft references");
1073 bool success = do_full_collection(false /* explicit gc */,
1074 true /* clear_all_soft_refs */,
1075 false /* do_maximal_compaction */);
1076 // do_full_collection only fails if blocked by GC locker and that can't
1077 // be the case here since we only call this when already completed one gc.
1078 assert(success, "invariant");
1079 return success;
1080 }
1081
1082 void G1CollectedHeap::resize_heap_if_necessary() {
1083 assert_at_safepoint_on_vm_thread();
1084
1085 bool should_expand;
1086 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1087
1088 if (resize_amount == 0) {
1089 return;
1090 } else if (should_expand) {
1091 expand(resize_amount, _workers);
1092 } else {
1093 shrink(resize_amount);
1094 }
1095 }
1096
1097 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1098 bool do_gc,
1099 bool maximal_compaction,
1100 bool expect_null_mutator_alloc_region,
1101 bool* gc_succeeded) {
1102 *gc_succeeded = true;
1103 // Let's attempt the allocation first.
1104 HeapWord* result =
1105 attempt_allocation_at_safepoint(word_size,
1106 expect_null_mutator_alloc_region);
1107 if (result != NULL) {
1108 return result;
1109 }
1110
1111 // In a G1 heap, we're supposed to keep allocation from failing by
1112 // incremental pauses. Therefore, at least for now, we'll favor
1113 // expansion over collection. (This might change in the future if we can
1114 // do something smarter than full collection to satisfy a failed alloc.)
1115 result = expand_and_allocate(word_size);
1116 if (result != NULL) {
1117 return result;
1118 }
1119
1120 if (do_gc) {
1121 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1122 // Expansion didn't work, we'll try to do a Full GC.
1123 // If maximal_compaction is set we clear all soft references and don't
1124 // allow any dead wood to be left on the heap.
1125 if (maximal_compaction) {
1126 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
1127 } else {
1128 log_info(gc, ergo)("Attempting full compaction");
1129 }
1130 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1131 maximal_compaction /* clear_all_soft_refs */ ,
1132 maximal_compaction /* do_maximal_compaction */);
1133 }
1134
1135 return NULL;
1136 }
1137
1138 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1139 bool* succeeded) {
1140 assert_at_safepoint_on_vm_thread();
1141
1142 // Attempts to allocate followed by Full GC.
1143 HeapWord* result =
1144 satisfy_failed_allocation_helper(word_size,
1145 true, /* do_gc */
1146 false, /* maximum_collection */
1147 false, /* expect_null_mutator_alloc_region */
1148 succeeded);
1149
1150 if (result != NULL || !*succeeded) {
1151 return result;
1152 }
1153
1154 // Attempts to allocate followed by Full GC that will collect all soft references.
1155 result = satisfy_failed_allocation_helper(word_size,
1156 true, /* do_gc */
1157 true, /* maximum_collection */
1158 true, /* expect_null_mutator_alloc_region */
1159 succeeded);
1160
1161 if (result != NULL || !*succeeded) {
1162 return result;
1163 }
1164
1165 // Attempts to allocate, no GC
1166 result = satisfy_failed_allocation_helper(word_size,
1167 false, /* do_gc */
1168 false, /* maximum_collection */
1169 true, /* expect_null_mutator_alloc_region */
1170 succeeded);
1171
1172 if (result != NULL) {
1173 return result;
1174 }
1175
1176 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1177 "Flag should have been handled and cleared prior to this point");
1178
1179 // What else? We might try synchronous finalization later. If the total
1180 // space available is large enough for the allocation, then a more
1181 // complete compaction phase than we've tried so far might be
1182 // appropriate.
1183 return NULL;
1184 }
1185
1186 // Attempting to expand the heap sufficiently
1187 // to support an allocation of the given "word_size". If
1188 // successful, perform the allocation and return the address of the
1189 // allocated block, or else "NULL".
1190
1191 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1192 assert_at_safepoint_on_vm_thread();
1193
1194 _verifier->verify_region_sets_optional();
1195
1196 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1197 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1198 word_size * HeapWordSize);
1199
1200
1201 if (expand(expand_bytes, _workers)) {
1202 _hrm.verify_optional();
1203 _verifier->verify_region_sets_optional();
1204 return attempt_allocation_at_safepoint(word_size,
1205 false /* expect_null_mutator_alloc_region */);
1206 }
1207 return NULL;
1208 }
1209
1210 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1211 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1212 aligned_expand_bytes = align_up(aligned_expand_bytes,
1213 HeapRegion::GrainBytes);
1214
1215 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1216 expand_bytes, aligned_expand_bytes);
1217
1218 if (is_maximal_no_gc()) {
1219 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1220 return false;
1221 }
1222
1223 double expand_heap_start_time_sec = os::elapsedTime();
1224 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1225 assert(regions_to_expand > 0, "Must expand by at least one region");
1226
1227 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1228 if (expand_time_ms != NULL) {
1229 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1230 }
1231
1232 if (expanded_by > 0) {
1233 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1234 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1235 policy()->record_new_heap_size(num_regions());
1236 } else {
1237 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1238
1239 // The expansion of the virtual storage space was unsuccessful.
1240 // Let's see if it was because we ran out of swap.
1241 if (G1ExitOnExpansionFailure &&
1242 _hrm.available() >= regions_to_expand) {
1243 // We had head room...
1244 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1245 }
1246 }
1247 return expanded_by > 0;
1248 }
1249
1250 bool G1CollectedHeap::expand_single_region(uint node_index) {
1251 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1252
1253 if (expanded_by == 0) {
1254 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1255 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1256 return false;
1257 }
1258
1259 policy()->record_new_heap_size(num_regions());
1260 return true;
1261 }
1262
1263 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1264 size_t aligned_shrink_bytes =
1265 ReservedSpace::page_align_size_down(shrink_bytes);
1266 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1267 HeapRegion::GrainBytes);
1268 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1269
1270 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1271 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1272
1273 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",
1274 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1275 if (num_regions_removed > 0) {
1276 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1277 policy()->record_new_heap_size(num_regions());
1278 } else {
1279 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1280 }
1281 }
1282
1283 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1284 _verifier->verify_region_sets_optional();
1285
1286 // We should only reach here at the end of a Full GC or during Remark which
1287 // means we should not not be holding to any GC alloc regions. The method
1288 // below will make sure of that and do any remaining clean up.
1289 _allocator->abandon_gc_alloc_regions();
1290
1291 // Instead of tearing down / rebuilding the free lists here, we
1292 // could instead use the remove_all_pending() method on free_list to
1293 // remove only the ones that we need to remove.
1294 _hrm.remove_all_free_regions();
1295 shrink_helper(shrink_bytes);
1296 rebuild_region_sets(true /* free_list_only */);
1297
1298 _hrm.verify_optional();
1299 _verifier->verify_region_sets_optional();
1300 }
1301
1302 class OldRegionSetChecker : public HeapRegionSetChecker {
1303 public:
1304 void check_mt_safety() {
1305 // Master Old Set MT safety protocol:
1306 // (a) If we're at a safepoint, operations on the master old set
1307 // should be invoked:
1308 // - by the VM thread (which will serialize them), or
1309 // - by the GC workers while holding the FreeList_lock, if we're
1310 // at a safepoint for an evacuation pause (this lock is taken
1311 // anyway when an GC alloc region is retired so that a new one
1312 // is allocated from the free list), or
1313 // - by the GC workers while holding the OldSets_lock, if we're at a
1314 // safepoint for a cleanup pause.
1315 // (b) If we're not at a safepoint, operations on the master old set
1316 // should be invoked while holding the Heap_lock.
1317
1318 if (SafepointSynchronize::is_at_safepoint()) {
1319 guarantee(Thread::current()->is_VM_thread() ||
1320 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1321 "master old set MT safety protocol at a safepoint");
1322 } else {
1323 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1324 }
1325 }
1326 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1327 const char* get_description() { return "Old Regions"; }
1328 };
1329
1330 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1331 public:
1332 void check_mt_safety() {
1333 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1334 "May only change archive regions during initialization or safepoint.");
1335 }
1336 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1337 const char* get_description() { return "Archive Regions"; }
1338 };
1339
1340 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1341 public:
1342 void check_mt_safety() {
1343 // Humongous Set MT safety protocol:
1344 // (a) If we're at a safepoint, operations on the master humongous
1345 // set should be invoked by either the VM thread (which will
1346 // serialize them) or by the GC workers while holding the
1347 // OldSets_lock.
1348 // (b) If we're not at a safepoint, operations on the master
1349 // humongous set should be invoked while holding the Heap_lock.
1350
1351 if (SafepointSynchronize::is_at_safepoint()) {
1352 guarantee(Thread::current()->is_VM_thread() ||
1353 OldSets_lock->owned_by_self(),
1354 "master humongous set MT safety protocol at a safepoint");
1355 } else {
1356 guarantee(Heap_lock->owned_by_self(),
1357 "master humongous set MT safety protocol outside a safepoint");
1358 }
1359 }
1360 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1361 const char* get_description() { return "Humongous Regions"; }
1362 };
1363
1364 G1CollectedHeap::G1CollectedHeap() :
1365 CollectedHeap(),
1366 _service_thread(NULL),
1367 _periodic_gc_task(NULL),
1368 _free_arena_memory_task(NULL),
1369 _workers(NULL),
1370 _card_table(NULL),
1371 _collection_pause_end(Ticks::now()),
1372 _soft_ref_policy(),
1373 _old_set("Old Region Set", new OldRegionSetChecker()),
1374 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1375 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1376 _bot(NULL),
1377 _listener(),
1378 _numa(G1NUMA::create()),
1379 _hrm(),
1380 _allocator(NULL),
1381 _evac_failure_injector(),
1382 _verifier(NULL),
1383 _summary_bytes_used(0),
1384 _bytes_used_during_gc(0),
1385 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1386 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1387 _monitoring_support(nullptr),
1388 _num_humongous_objects(0),
1389 _num_humongous_reclaim_candidates(0),
1390 _hr_printer(),
1391 _collector_state(),
1392 _old_marking_cycles_started(0),
1393 _old_marking_cycles_completed(0),
1394 _eden(),
1395 _survivor(),
1396 _gc_timer_stw(new STWGCTimer()),
1397 _gc_tracer_stw(new G1NewTracer()),
1398 _policy(new G1Policy(_gc_timer_stw)),
1399 _heap_sizing_policy(NULL),
1400 _collection_set(this, _policy),
1401 _rem_set(NULL),
1402 _card_set_config(),
1403 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1404 _cm(NULL),
1405 _cm_thread(NULL),
1406 _cr(NULL),
1407 _task_queues(NULL),
1408 _ref_processor_stw(NULL),
1409 _is_alive_closure_stw(this),
1410 _is_subject_to_discovery_stw(this),
1411 _ref_processor_cm(NULL),
1412 _is_alive_closure_cm(this),
1413 _is_subject_to_discovery_cm(this),
1414 _region_attr() {
1415
1416 _verifier = new G1HeapVerifier(this);
1417
1418 _allocator = new G1Allocator(this);
1419
1420 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1421
1422 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1423
1424 // Override the default _filler_array_max_size so that no humongous filler
1425 // objects are created.
1426 _filler_array_max_size = _humongous_object_threshold_in_words;
1427
1428 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1429 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1430
1431 uint n_queues = ParallelGCThreads;
1432 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1433
1434 for (uint i = 0; i < n_queues; i++) {
1435 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1436 _task_queues->register_queue(i, q);
1437 }
1438
1439 _gc_tracer_stw->initialize();
1440
1441 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1442 }
1443
1444 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1445 size_t size,
1446 size_t translation_factor) {
1447 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1448 // Allocate a new reserved space, preferring to use large pages.
1449 ReservedSpace rs(size, preferred_page_size);
1450 size_t page_size = rs.page_size();
1451 G1RegionToSpaceMapper* result =
1452 G1RegionToSpaceMapper::create_mapper(rs,
1453 size,
1454 page_size,
1455 HeapRegion::GrainBytes,
1456 translation_factor,
1457 mtGC);
1458
1459 os::trace_page_sizes_for_requested_size(description,
1460 size,
1461 page_size,
1462 preferred_page_size,
1463 rs.base(),
1464 rs.size());
1465
1466 return result;
1467 }
1468
1469 jint G1CollectedHeap::initialize_concurrent_refinement() {
1470 jint ecode = JNI_OK;
1471 _cr = G1ConcurrentRefine::create(policy(), &ecode);
1472 return ecode;
1473 }
1474
1475 jint G1CollectedHeap::initialize_service_thread() {
1476 _service_thread = new G1ServiceThread();
1477 if (_service_thread->osthread() == NULL) {
1478 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1479 return JNI_ENOMEM;
1480 }
1481 return JNI_OK;
1482 }
1483
1484 jint G1CollectedHeap::initialize() {
1485
1486 // Necessary to satisfy locking discipline assertions.
1487
1488 MutexLocker x(Heap_lock);
1489
1490 // While there are no constraints in the GC code that HeapWordSize
1491 // be any particular value, there are multiple other areas in the
1492 // system which believe this to be true (e.g. oop->object_size in some
1493 // cases incorrectly returns the size in wordSize units rather than
1494 // HeapWordSize).
1495 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1496
1497 size_t init_byte_size = InitialHeapSize;
1498 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1499
1500 // Ensure that the sizes are properly aligned.
1501 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1502 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1503 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1504
1505 // Reserve the maximum.
1506
1507 // When compressed oops are enabled, the preferred heap base
1508 // is calculated by subtracting the requested size from the
1509 // 32Gb boundary and using the result as the base address for
1510 // heap reservation. If the requested size is not aligned to
1511 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1512 // into the ReservedHeapSpace constructor) then the actual
1513 // base of the reserved heap may end up differing from the
1514 // address that was requested (i.e. the preferred heap base).
1515 // If this happens then we could end up using a non-optimal
1516 // compressed oops mode.
1517
1518 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1519 HeapAlignment);
1520
1521 initialize_reserved_region(heap_rs);
1522
1523 // Create the barrier set for the entire reserved region.
1524 G1CardTable* ct = new G1CardTable(heap_rs.region());
1525 ct->initialize();
1526 G1BarrierSet* bs = new G1BarrierSet(ct);
1527 bs->initialize();
1528 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1529 BarrierSet::set_barrier_set(bs);
1530 _card_table = ct;
1531
1532 {
1533 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1534 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1535 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1536 }
1537
1538 // Create space mappers.
1539 size_t page_size = heap_rs.page_size();
1540 G1RegionToSpaceMapper* heap_storage =
1541 G1RegionToSpaceMapper::create_mapper(heap_rs,
1542 heap_rs.size(),
1543 page_size,
1544 HeapRegion::GrainBytes,
1545 1,
1546 mtJavaHeap);
1547 if(heap_storage == NULL) {
1548 vm_shutdown_during_initialization("Could not initialize G1 heap");
1549 return JNI_ERR;
1550 }
1551
1552 os::trace_page_sizes("Heap",
1553 MinHeapSize,
1554 reserved_byte_size,
1555 page_size,
1556 heap_rs.base(),
1557 heap_rs.size());
1558 heap_storage->set_mapping_changed_listener(&_listener);
1559
1560 // Create storage for the BOT, card table and the bitmap.
1561 G1RegionToSpaceMapper* bot_storage =
1562 create_aux_memory_mapper("Block Offset Table",
1563 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1564 G1BlockOffsetTable::heap_map_factor());
1565
1566 G1RegionToSpaceMapper* cardtable_storage =
1567 create_aux_memory_mapper("Card Table",
1568 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1569 G1CardTable::heap_map_factor());
1570
1571 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1572 G1RegionToSpaceMapper* bitmap_storage =
1573 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1574
1575 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1576 _card_table->initialize(cardtable_storage);
1577
1578 // 6843694 - ensure that the maximum region index can fit
1579 // in the remembered set structures.
1580 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1581 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1582
1583 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1584 // start within the first card.
1585 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1586 G1FromCardCache::initialize(max_reserved_regions());
1587 // Also create a G1 rem set.
1588 _rem_set = new G1RemSet(this, _card_table);
1589 _rem_set->initialize(max_reserved_regions());
1590
1591 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1592 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1593 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1594 "too many cards per region");
1595
1596 HeapRegionRemSet::initialize(_reserved);
1597
1598 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1599
1600 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1601
1602 {
1603 size_t granularity = HeapRegion::GrainBytes;
1604
1605 _region_attr.initialize(reserved(), granularity);
1606 }
1607
1608 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1609 if (_workers == NULL) {
1610 return JNI_ENOMEM;
1611 }
1612 _workers->initialize_workers();
1613
1614 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1615
1616 // Create the G1ConcurrentMark data structure and thread.
1617 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1618 _cm = new G1ConcurrentMark(this, bitmap_storage);
1619 _cm_thread = _cm->cm_thread();
1620
1621 // Now expand into the initial heap size.
1622 if (!expand(init_byte_size, _workers)) {
1623 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1624 return JNI_ENOMEM;
1625 }
1626
1627 // Perform any initialization actions delegated to the policy.
1628 policy()->init(this, &_collection_set);
1629
1630 jint ecode = initialize_concurrent_refinement();
1631 if (ecode != JNI_OK) {
1632 return ecode;
1633 }
1634
1635 ecode = initialize_service_thread();
1636 if (ecode != JNI_OK) {
1637 return ecode;
1638 }
1639
1640 // Create and schedule the periodic gc task on the service thread.
1641 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1642 _service_thread->register_task(_periodic_gc_task);
1643
1644 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1645 _service_thread->register_task(_free_arena_memory_task);
1646
1647 // Here we allocate the dummy HeapRegion that is required by the
1648 // G1AllocRegion class.
1649 HeapRegion* dummy_region = _hrm.get_dummy_region();
1650
1651 // We'll re-use the same region whether the alloc region will
1652 // require BOT updates or not and, if it doesn't, then a non-young
1653 // region will complain that it cannot support allocations without
1654 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1655 dummy_region->set_eden();
1656 // Make sure it's full.
1657 dummy_region->set_top(dummy_region->end());
1658 G1AllocRegion::setup(this, dummy_region);
1659
1660 _allocator->init_mutator_alloc_regions();
1661
1662 // Do create of the monitoring and management support so that
1663 // values in the heap have been properly initialized.
1664 _monitoring_support = new G1MonitoringSupport(this);
1665
1666 _collection_set.initialize(max_reserved_regions());
1667
1668 evac_failure_injector()->reset();
1669
1670 G1InitLogger::print();
1671
1672 return JNI_OK;
1673 }
1674
1675 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1676 return _cm_thread->should_terminate();
1677 }
1678
1679 void G1CollectedHeap::stop() {
1680 // Stop all concurrent threads. We do this to make sure these threads
1681 // do not continue to execute and access resources (e.g. logging)
1682 // that are destroyed during shutdown.
1683 _cr->stop();
1684 _service_thread->stop();
1685 _cm_thread->stop();
1686 }
1687
1688 void G1CollectedHeap::safepoint_synchronize_begin() {
1689 SuspendibleThreadSet::synchronize();
1690 }
1691
1692 void G1CollectedHeap::safepoint_synchronize_end() {
1693 SuspendibleThreadSet::desynchronize();
1694 }
1695
1696 void G1CollectedHeap::post_initialize() {
1697 CollectedHeap::post_initialize();
1698 ref_processing_init();
1699 }
1700
1701 void G1CollectedHeap::ref_processing_init() {
1702 // Reference processing in G1 currently works as follows:
1703 //
1704 // * There are two reference processor instances. One is
1705 // used to record and process discovered references
1706 // during concurrent marking; the other is used to
1707 // record and process references during STW pauses
1708 // (both full and incremental).
1709 // * Both ref processors need to 'span' the entire heap as
1710 // the regions in the collection set may be dotted around.
1711 //
1712 // * For the concurrent marking ref processor:
1713 // * Reference discovery is enabled at concurrent start.
1714 // * Reference discovery is disabled and the discovered
1715 // references processed etc during remarking.
1716 // * Reference discovery is MT (see below).
1717 // * Reference discovery requires a barrier (see below).
1718 // * Reference processing may or may not be MT
1719 // (depending on the value of ParallelRefProcEnabled
1720 // and ParallelGCThreads).
1721 // * A full GC disables reference discovery by the CM
1722 // ref processor and abandons any entries on it's
1723 // discovered lists.
1724 //
1725 // * For the STW processor:
1726 // * Non MT discovery is enabled at the start of a full GC.
1727 // * Processing and enqueueing during a full GC is non-MT.
1728 // * During a full GC, references are processed after marking.
1729 //
1730 // * Discovery (may or may not be MT) is enabled at the start
1731 // of an incremental evacuation pause.
1732 // * References are processed near the end of a STW evacuation pause.
1733 // * For both types of GC:
1734 // * Discovery is atomic - i.e. not concurrent.
1735 // * Reference discovery will not need a barrier.
1736
1737 // Concurrent Mark ref processor
1738 _ref_processor_cm =
1739 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1740 ParallelGCThreads, // degree of mt processing
1741 // We discover with the gc worker threads during Remark, so both
1742 // thread counts must be considered for discovery.
1743 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1744 true, // Reference discovery is concurrent
1745 &_is_alive_closure_cm); // is alive closure
1746
1747 // STW ref processor
1748 _ref_processor_stw =
1749 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1750 ParallelGCThreads, // degree of mt processing
1751 ParallelGCThreads, // degree of mt discovery
1752 false, // Reference discovery is not concurrent
1753 &_is_alive_closure_stw); // is alive closure
1754 }
1755
1756 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1757 return &_soft_ref_policy;
1758 }
1759
1760 size_t G1CollectedHeap::capacity() const {
1761 return _hrm.length() * HeapRegion::GrainBytes;
1762 }
1763
1764 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1765 return _hrm.total_free_bytes();
1766 }
1767
1768 // Computes the sum of the storage used by the various regions.
1769 size_t G1CollectedHeap::used() const {
1770 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1771 return result;
1772 }
1773
1774 size_t G1CollectedHeap::used_unlocked() const {
1775 return _summary_bytes_used;
1776 }
1777
1778 class SumUsedClosure: public HeapRegionClosure {
1779 size_t _used;
1780 public:
1781 SumUsedClosure() : _used(0) {}
1782 bool do_heap_region(HeapRegion* r) {
1783 _used += r->used();
1784 return false;
1785 }
1786 size_t result() { return _used; }
1787 };
1788
1789 size_t G1CollectedHeap::recalculate_used() const {
1790 SumUsedClosure blk;
1791 heap_region_iterate(&blk);
1792 return blk.result();
1793 }
1794
1795 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1796 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1797 }
1798
1799 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1800 switch (cause) {
1801 case GCCause::_g1_humongous_allocation: return true;
1802 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1803 case GCCause::_wb_breakpoint: return true;
1804 case GCCause::_codecache_GC_aggressive: return true;
1805 case GCCause::_codecache_GC_threshold: return true;
1806 default: return is_user_requested_concurrent_full_gc(cause);
1807 }
1808 }
1809
1810 void G1CollectedHeap::increment_old_marking_cycles_started() {
1811 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1812 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1813 "Wrong marking cycle count (started: %d, completed: %d)",
1814 _old_marking_cycles_started, _old_marking_cycles_completed);
1815
1816 _old_marking_cycles_started++;
1817 }
1818
1819 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1820 bool whole_heap_examined) {
1821 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1822
1823 // We assume that if concurrent == true, then the caller is a
1824 // concurrent thread that was joined the Suspendible Thread
1825 // Set. If there's ever a cheap way to check this, we should add an
1826 // assert here.
1827
1828 // Given that this method is called at the end of a Full GC or of a
1829 // concurrent cycle, and those can be nested (i.e., a Full GC can
1830 // interrupt a concurrent cycle), the number of full collections
1831 // completed should be either one (in the case where there was no
1832 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1833 // behind the number of full collections started.
1834
1835 // This is the case for the inner caller, i.e. a Full GC.
1836 assert(concurrent ||
1837 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1838 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1839 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1840 "is inconsistent with _old_marking_cycles_completed = %u",
1841 _old_marking_cycles_started, _old_marking_cycles_completed);
1842
1843 // This is the case for the outer caller, i.e. the concurrent cycle.
1844 assert(!concurrent ||
1845 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1846 "for outer caller (concurrent cycle): "
1847 "_old_marking_cycles_started = %u "
1848 "is inconsistent with _old_marking_cycles_completed = %u",
1849 _old_marking_cycles_started, _old_marking_cycles_completed);
1850
1851 _old_marking_cycles_completed += 1;
1852 if (whole_heap_examined) {
1853 // Signal that we have completed a visit to all live objects.
1854 record_whole_heap_examined_timestamp();
1855 }
1856
1857 // We need to clear the "in_progress" flag in the CM thread before
1858 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1859 // is set) so that if a waiter requests another System.gc() it doesn't
1860 // incorrectly see that a marking cycle is still in progress.
1861 if (concurrent) {
1862 _cm_thread->set_idle();
1863 }
1864
1865 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1866 // for a full GC to finish that their wait is over.
1867 ml.notify_all();
1868 }
1869
1870 // Helper for collect().
1871 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1872 MutexLocker ml(Heap_lock);
1873 return G1GCCounters(g1h);
1874 }
1875
1876 void G1CollectedHeap::collect(GCCause::Cause cause) {
1877 try_collect(cause, collection_counters(this));
1878 }
1879
1880 // Return true if (x < y) with allowance for wraparound.
1881 static bool gc_counter_less_than(uint x, uint y) {
1882 return (x - y) > (UINT_MAX/2);
1883 }
1884
1885 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1886 // Macro so msg printing is format-checked.
1887 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
1888 do { \
1889 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
1890 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
1891 ResourceMark rm; /* For thread name. */ \
1892 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1893 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1894 Thread::current()->name(), \
1895 GCCause::to_string(cause)); \
1896 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
1897 } \
1898 } while (0)
1899
1900 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1901 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1902
1903 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1904 uint gc_counter,
1905 uint old_marking_started_before) {
1906 assert_heap_not_locked();
1907 assert(should_do_concurrent_full_gc(cause),
1908 "Non-concurrent cause %s", GCCause::to_string(cause));
1909
1910 for (uint i = 1; true; ++i) {
1911 // Try to schedule concurrent start evacuation pause that will
1912 // start a concurrent cycle.
1913 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1914 VM_G1TryInitiateConcMark op(gc_counter, cause);
1915 VMThread::execute(&op);
1916
1917 // Request is trivially finished.
1918 if (cause == GCCause::_g1_periodic_collection) {
1919 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1920 return op.gc_succeeded();
1921 }
1922
1923 // If VMOp skipped initiating concurrent marking cycle because
1924 // we're terminating, then we're done.
1925 if (op.terminating()) {
1926 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1927 return false;
1928 }
1929
1930 // Lock to get consistent set of values.
1931 uint old_marking_started_after;
1932 uint old_marking_completed_after;
1933 {
1934 MutexLocker ml(Heap_lock);
1935 // Update gc_counter for retrying VMOp if needed. Captured here to be
1936 // consistent with the values we use below for termination tests. If
1937 // a retry is needed after a possible wait, and another collection
1938 // occurs in the meantime, it will cause our retry to be skipped and
1939 // we'll recheck for termination with updated conditions from that
1940 // more recent collection. That's what we want, rather than having
1941 // our retry possibly perform an unnecessary collection.
1942 gc_counter = total_collections();
1943 old_marking_started_after = _old_marking_cycles_started;
1944 old_marking_completed_after = _old_marking_cycles_completed;
1945 }
1946
1947 if (cause == GCCause::_wb_breakpoint) {
1948 if (op.gc_succeeded()) {
1949 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1950 return true;
1951 }
1952 // When _wb_breakpoint there can't be another cycle or deferred.
1953 assert(!op.cycle_already_in_progress(), "invariant");
1954 assert(!op.whitebox_attached(), "invariant");
1955 // Concurrent cycle attempt might have been cancelled by some other
1956 // collection, so retry. Unlike other cases below, we want to retry
1957 // even if cancelled by a STW full collection, because we really want
1958 // to start a concurrent cycle.
1959 if (old_marking_started_before != old_marking_started_after) {
1960 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1961 old_marking_started_before = old_marking_started_after;
1962 }
1963 } else if (!GCCause::is_user_requested_gc(cause)) {
1964 // For an "automatic" (not user-requested) collection, we just need to
1965 // ensure that progress is made.
1966 //
1967 // Request is finished if any of
1968 // (1) the VMOp successfully performed a GC,
1969 // (2) a concurrent cycle was already in progress,
1970 // (3) whitebox is controlling concurrent cycles,
1971 // (4) a new cycle was started (by this thread or some other), or
1972 // (5) a Full GC was performed.
1973 // Cases (4) and (5) are detected together by a change to
1974 // _old_marking_cycles_started.
1975 //
1976 // Note that (1) does not imply (4). If we're still in the mixed
1977 // phase of an earlier concurrent collection, the request to make the
1978 // collection a concurrent start won't be honored. If we don't check for
1979 // both conditions we'll spin doing back-to-back collections.
1980 if (op.gc_succeeded() ||
1981 op.cycle_already_in_progress() ||
1982 op.whitebox_attached() ||
1983 (old_marking_started_before != old_marking_started_after)) {
1984 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1985 return true;
1986 }
1987 } else { // User-requested GC.
1988 // For a user-requested collection, we want to ensure that a complete
1989 // full collection has been performed before returning, but without
1990 // waiting for more than needed.
1991
1992 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1993 // new cycle was started. That's good, because it's not clear what we
1994 // should do otherwise. Trying again just does back to back GCs.
1995 // Can't wait for someone else to start a cycle. And returning fails
1996 // to meet the goal of ensuring a full collection was performed.
1997 assert(!op.gc_succeeded() ||
1998 (old_marking_started_before != old_marking_started_after),
1999 "invariant: succeeded %s, started before %u, started after %u",
2000 BOOL_TO_STR(op.gc_succeeded()),
2001 old_marking_started_before, old_marking_started_after);
2002
2003 // Request is finished if a full collection (concurrent or stw)
2004 // was started after this request and has completed, e.g.
2005 // started_before < completed_after.
2006 if (gc_counter_less_than(old_marking_started_before,
2007 old_marking_completed_after)) {
2008 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2009 return true;
2010 }
2011
2012 if (old_marking_started_after != old_marking_completed_after) {
2013 // If there is an in-progress cycle (possibly started by us), then
2014 // wait for that cycle to complete, e.g.
2015 // while completed_now < started_after.
2016 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2017 MonitorLocker ml(G1OldGCCount_lock);
2018 while (gc_counter_less_than(_old_marking_cycles_completed,
2019 old_marking_started_after)) {
2020 ml.wait();
2021 }
2022 // Request is finished if the collection we just waited for was
2023 // started after this request.
2024 if (old_marking_started_before != old_marking_started_after) {
2025 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2026 return true;
2027 }
2028 }
2029
2030 // If VMOp was successful then it started a new cycle that the above
2031 // wait &etc should have recognized as finishing this request. This
2032 // differs from a non-user-request, where gc_succeeded does not imply
2033 // a new cycle was started.
2034 assert(!op.gc_succeeded(), "invariant");
2035
2036 if (op.cycle_already_in_progress()) {
2037 // If VMOp failed because a cycle was already in progress, it
2038 // is now complete. But it didn't finish this user-requested
2039 // GC, so try again.
2040 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2041 continue;
2042 } else if (op.whitebox_attached()) {
2043 // If WhiteBox wants control, wait for notification of a state
2044 // change in the controller, then try again. Don't wait for
2045 // release of control, since collections may complete while in
2046 // control. Note: This won't recognize a STW full collection
2047 // while waiting; we can't wait on multiple monitors.
2048 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2049 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2050 if (ConcurrentGCBreakpoints::is_controlled()) {
2051 ml.wait();
2052 }
2053 continue;
2054 }
2055 }
2056
2057 // Collection failed and should be retried.
2058 assert(op.transient_failure(), "invariant");
2059
2060 if (GCLocker::is_active_and_needs_gc()) {
2061 // If GCLocker is active, wait until clear before retrying.
2062 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2063 GCLocker::stall_until_clear();
2064 }
2065
2066 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2067 }
2068 }
2069
2070 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
2071 const G1GCCounters& counters_before) {
2072 if (should_do_concurrent_full_gc(cause)) {
2073 return try_collect_concurrently(cause,
2074 counters_before.total_collections(),
2075 counters_before.old_marking_cycles_started());
2076 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
2077 // Indicate failure to be consistent with VMOp failure due to
2078 // another collection slipping in after our gc_count but before
2079 // our request is processed.
2080 return false;
2081 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2082 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2083
2084 // Schedule a standard evacuation pause. We're setting word_size
2085 // to 0 which means that we are not requesting a post-GC allocation.
2086 VM_G1CollectForAllocation op(0, /* word_size */
2087 counters_before.total_collections(),
2088 cause);
2089 VMThread::execute(&op);
2090 return op.gc_succeeded();
2091 } else {
2092 // Schedule a Full GC.
2093 VM_G1CollectFull op(counters_before.total_collections(),
2094 counters_before.total_full_collections(),
2095 cause);
2096 VMThread::execute(&op);
2097 return op.gc_succeeded();
2098 }
2099 }
2100
2101 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
2102 GCCauseSetter x(this, gc_cause);
2103
2104 // At this point we are supposed to start a concurrent cycle. We
2105 // will do so if one is not already in progress.
2106 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
2107 if (should_start) {
2108 do_collection_pause_at_safepoint();
2109 }
2110 }
2111
2112 bool G1CollectedHeap::is_in(const void* p) const {
2113 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
2114 }
2115
2116 // Iteration functions.
2117
2118 // Iterates an ObjectClosure over all objects within a HeapRegion.
2119
2120 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2121 ObjectClosure* _cl;
2122 public:
2123 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2124 bool do_heap_region(HeapRegion* r) {
2125 if (!r->is_continues_humongous()) {
2126 r->object_iterate(_cl);
2127 }
2128 return false;
2129 }
2130 };
2131
2132 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2133 IterateObjectClosureRegionClosure blk(cl);
2134 heap_region_iterate(&blk);
2135 }
2136
2137 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2138 private:
2139 G1CollectedHeap* _heap;
2140 HeapRegionClaimer _claimer;
2141
2142 public:
2143 G1ParallelObjectIterator(uint thread_num) :
2144 _heap(G1CollectedHeap::heap()),
2145 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2146
2147 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2148 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2149 }
2150 };
2151
2152 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2153 return new G1ParallelObjectIterator(thread_num);
2154 }
2155
2156 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2157 IterateObjectClosureRegionClosure blk(cl);
2158 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2159 }
2160
2161 void G1CollectedHeap::keep_alive(oop obj) {
2162 G1BarrierSet::enqueue_preloaded(obj);
2163 }
2164
2165 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2166 _hrm.iterate(cl);
2167 }
2168
2169 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
2170 _hrm.iterate(cl);
2171 }
2172
2173 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2174 HeapRegionClaimer *hrclaimer,
2175 uint worker_id) const {
2176 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2177 }
2178
2179 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2180 HeapRegionClaimer *hrclaimer) const {
2181 _hrm.par_iterate(cl, hrclaimer, 0);
2182 }
2183
2184 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2185 _collection_set.iterate(cl);
2186 }
2187
2188 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2189 HeapRegionClaimer* hr_claimer,
2190 uint worker_id) {
2191 _collection_set.par_iterate(cl, hr_claimer, worker_id);
2192 }
2193
2194 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2195 HeapRegionClaimer* hr_claimer,
2196 uint worker_id) {
2197 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2198 }
2199
2200 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2201 HeapRegionClaimer* hr_claimer,
2202 const uint regions[],
2203 size_t length,
2204 uint worker_id) const {
2205 assert_at_safepoint();
2206 if (length == 0) {
2207 return;
2208 }
2209 uint total_workers = workers()->active_workers();
2210
2211 size_t start_pos = (worker_id * length) / total_workers;
2212 size_t cur_pos = start_pos;
2213
2214 do {
2215 uint region_idx = regions[cur_pos];
2216 if (hr_claimer == NULL || hr_claimer->claim_region(region_idx)) {
2217 HeapRegion* r = region_at(region_idx);
2218 bool result = cl->do_heap_region(r);
2219 guarantee(!result, "Must not cancel iteration");
2220 }
2221
2222 cur_pos++;
2223 if (cur_pos == length) {
2224 cur_pos = 0;
2225 }
2226 } while (cur_pos != start_pos);
2227 }
2228
2229 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2230 HeapRegion* hr = heap_region_containing(addr);
2231 // The CollectedHeap API requires us to not fail for any given address within
2232 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2233 // outside of the allocated area.
2234 if (addr >= hr->top()) {
2235 return nullptr;
2236 }
2237 return hr->block_start(addr);
2238 }
2239
2240 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2241 HeapRegion* hr = heap_region_containing(addr);
2242 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2243 }
2244
2245 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2246 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2247 }
2248
2249 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2250 return _eden.length() * HeapRegion::GrainBytes;
2251 }
2252
2253 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2254 // must be equal to the humongous object limit.
2255 size_t G1CollectedHeap::max_tlab_size() const {
2256 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2257 }
2258
2259 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2260 return _allocator->unsafe_max_tlab_alloc();
2261 }
2262
2263 size_t G1CollectedHeap::max_capacity() const {
2264 return max_regions() * HeapRegion::GrainBytes;
2265 }
2266
2267 void G1CollectedHeap::prepare_for_verify() {
2268 _verifier->prepare_for_verify();
2269 }
2270
2271 void G1CollectedHeap::verify(VerifyOption vo) {
2272 _verifier->verify(vo);
2273 }
2274
2275 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2276 return true;
2277 }
2278
2279 bool G1CollectedHeap::is_archived_object(oop object) const {
2280 return object != NULL && heap_region_containing(object)->is_archive();
2281 }
2282
2283 class PrintRegionClosure: public HeapRegionClosure {
2284 outputStream* _st;
2285 public:
2286 PrintRegionClosure(outputStream* st) : _st(st) {}
2287 bool do_heap_region(HeapRegion* r) {
2288 r->print_on(_st);
2289 return false;
2290 }
2291 };
2292
2293 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2294 const HeapRegion* hr,
2295 const VerifyOption vo) const {
2296 switch (vo) {
2297 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2298 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2299 default: ShouldNotReachHere();
2300 }
2301 return false; // keep some compilers happy
2302 }
2303
2304 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2305 const VerifyOption vo) const {
2306 switch (vo) {
2307 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2308 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2309 default: ShouldNotReachHere();
2310 }
2311 return false; // keep some compilers happy
2312 }
2313
2314 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) {
2315 GCLocker::lock_critical(thread);
2316 }
2317
2318 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
2319 GCLocker::unlock_critical(thread);
2320 }
2321
2322 void G1CollectedHeap::print_heap_regions() const {
2323 LogTarget(Trace, gc, heap, region) lt;
2324 if (lt.is_enabled()) {
2325 LogStream ls(lt);
2326 print_regions_on(&ls);
2327 }
2328 }
2329
2330 void G1CollectedHeap::print_on(outputStream* st) const {
2331 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2332 st->print(" %-20s", "garbage-first heap");
2333 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2334 capacity()/K, heap_used/K);
2335 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2336 p2i(_hrm.reserved().start()),
2337 p2i(_hrm.reserved().end()));
2338 st->cr();
2339 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2340 uint young_regions = young_regions_count();
2341 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2342 (size_t) young_regions * HeapRegion::GrainBytes / K);
2343 uint survivor_regions = survivor_regions_count();
2344 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2345 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2346 st->cr();
2347 if (_numa->is_enabled()) {
2348 uint num_nodes = _numa->num_active_nodes();
2349 st->print(" remaining free region(s) on each NUMA node: ");
2350 const int* node_ids = _numa->node_ids();
2351 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2352 uint num_free_regions = _hrm.num_free_regions(node_index);
2353 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2354 }
2355 st->cr();
2356 }
2357 MetaspaceUtils::print_on(st);
2358 }
2359
2360 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2361 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2362 "HS=humongous(starts), HC=humongous(continues), "
2363 "CS=collection set, F=free, "
2364 "OA=open archive, CA=closed archive, "
2365 "TAMS=top-at-mark-start, "
2366 "PB=parsable bottom");
2367 PrintRegionClosure blk(st);
2368 heap_region_iterate(&blk);
2369 }
2370
2371 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2372 print_on(st);
2373
2374 // Print the per-region information.
2375 st->cr();
2376 print_regions_on(st);
2377 }
2378
2379 void G1CollectedHeap::print_on_error(outputStream* st) const {
2380 this->CollectedHeap::print_on_error(st);
2381
2382 if (_cm != NULL) {
2383 st->cr();
2384 _cm->print_on_error(st);
2385 }
2386 }
2387
2388 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2389 workers()->threads_do(tc);
2390 tc->do_thread(_cm_thread);
2391 _cm->threads_do(tc);
2392 _cr->threads_do(tc);
2393 tc->do_thread(_service_thread);
2394 }
2395
2396 void G1CollectedHeap::print_tracing_info() const {
2397 rem_set()->print_summary_info();
2398 concurrent_mark()->print_summary_info();
2399 }
2400
2401 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2402 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2403 }
2404
2405 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2406
2407 size_t eden_used_bytes = _monitoring_support->eden_space_used();
2408 size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2409 size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2410 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2411
2412 size_t eden_capacity_bytes =
2413 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2414
2415 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2416 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2417 survivor_used_bytes, old_gen_used_bytes, num_regions());
2418 }
2419
2420 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2421 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2422 stats->unused(), stats->used(), stats->region_end_waste(),
2423 stats->regions_filled(), stats->num_plab_filled(),
2424 stats->direct_allocated(), stats->num_direct_allocated(),
2425 stats->failure_used(), stats->failure_waste());
2426 }
2427
2428 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2429 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2430 gc_tracer->report_gc_heap_summary(when, heap_summary);
2431
2432 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2433 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2434 }
2435
2436 void G1CollectedHeap::gc_prologue(bool full) {
2437 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2438
2439 // Update common counters.
2440 increment_total_collections(full /* full gc */);
2441 if (full || collector_state()->in_concurrent_start_gc()) {
2442 increment_old_marking_cycles_started();
2443 }
2444 }
2445
2446 void G1CollectedHeap::gc_epilogue(bool full) {
2447 // Update common counters.
2448 if (full) {
2449 // Update the number of full collections that have been completed.
2450 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2451 }
2452
2453 #if COMPILER2_OR_JVMCI
2454 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2455 #endif
2456
2457 // We have just completed a GC. Update the soft reference
2458 // policy with the new heap occupancy
2459 Universe::heap()->update_capacity_and_used_at_gc();
2460
2461 _collection_pause_end = Ticks::now();
2462
2463 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2464 &_collection_set_candidates_card_set_stats);
2465 }
2466
2467 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2468 return _hrm.uncommit_inactive_regions(region_limit);
2469 }
2470
2471 bool G1CollectedHeap::has_uncommittable_regions() {
2472 return _hrm.has_inactive_regions();
2473 }
2474
2475 void G1CollectedHeap::uncommit_regions_if_necessary() {
2476 if (has_uncommittable_regions()) {
2477 G1UncommitRegionTask::enqueue();
2478 }
2479 }
2480
2481 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2482 LogTarget(Trace, gc, heap, verify) lt;
2483
2484 if (lt.is_enabled()) {
2485 LogStream ls(lt);
2486 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2487 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2488 heap_region_iterate(&cl);
2489 }
2490 }
2491
2492 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2493 uint gc_count_before,
2494 bool* succeeded,
2495 GCCause::Cause gc_cause) {
2496 assert_heap_not_locked_and_not_at_safepoint();
2497 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2498 VMThread::execute(&op);
2499
2500 HeapWord* result = op.result();
2501 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2502 assert(result == NULL || ret_succeeded,
2503 "the result should be NULL if the VM did not succeed");
2504 *succeeded = ret_succeeded;
2505
2506 assert_heap_not_locked();
2507 return result;
2508 }
2509
2510 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2511 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2512
2513 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2514 if (concurrent_operation_is_full_mark) {
2515 _cm->post_concurrent_mark_start();
2516 _cm_thread->start_full_mark();
2517 } else {
2518 _cm->post_concurrent_undo_start();
2519 _cm_thread->start_undo_mark();
2520 }
2521 CGC_lock->notify();
2522 }
2523
2524 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2525 // We don't nominate objects with many remembered set entries, on
2526 // the assumption that such objects are likely still live.
2527 HeapRegionRemSet* rem_set = r->rem_set();
2528
2529 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2530 }
2531
2532 #ifndef PRODUCT
2533 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2534 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2535 public:
2536 virtual bool do_heap_region(HeapRegion* r) {
2537 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2538 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2539 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2540 "Region %u remset tracking status (%s) different to region attribute (%s)",
2541 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2542 return false;
2543 }
2544 } cl;
2545 heap_region_iterate(&cl);
2546 }
2547 #endif
2548
2549 void G1CollectedHeap::start_new_collection_set() {
2550 collection_set()->start_incremental_building();
2551
2552 clear_region_attr();
2553
2554 guarantee(_eden.length() == 0, "eden should have been cleared");
2555 policy()->transfer_survivors_to_cset(survivor());
2556
2557 // We redo the verification but now wrt to the new CSet which
2558 // has just got initialized after the previous CSet was freed.
2559 _cm->verify_no_collection_set_oops();
2560 }
2561
2562 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2563 if (collector_state()->in_concurrent_start_gc()) {
2564 return G1HeapVerifier::G1VerifyConcurrentStart;
2565 } else if (collector_state()->in_young_only_phase()) {
2566 return G1HeapVerifier::G1VerifyYoungNormal;
2567 } else {
2568 return G1HeapVerifier::G1VerifyMixed;
2569 }
2570 }
2571
2572 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2573 if (!VerifyBeforeGC) {
2574 return;
2575 }
2576 Ticks start = Ticks::now();
2577 _verifier->prepare_for_verify();
2578 _verifier->verify_region_sets_optional();
2579 _verifier->verify_dirty_young_regions();
2580 _verifier->verify_before_gc(type);
2581 verify_numa_regions("GC Start");
2582 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2583 }
2584
2585 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2586 if (!VerifyAfterGC) {
2587 return;
2588 }
2589 Ticks start = Ticks::now();
2590 _verifier->verify_after_gc(type);
2591 verify_numa_regions("GC End");
2592 _verifier->verify_region_sets_optional();
2593 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2594 }
2595
2596 void G1CollectedHeap::expand_heap_after_young_collection(){
2597 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2598 if (expand_bytes > 0) {
2599 // No need for an ergo logging here,
2600 // expansion_amount() does this when it returns a value > 0.
2601 double expand_ms = 0.0;
2602 if (!expand(expand_bytes, _workers, &expand_ms)) {
2603 // We failed to expand the heap. Cannot do anything about it.
2604 }
2605 phase_times()->record_expand_heap_time(expand_ms);
2606 }
2607 }
2608
2609 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2610 assert_at_safepoint_on_vm_thread();
2611 guarantee(!is_gc_active(), "collection is not reentrant");
2612
2613 if (GCLocker::check_active_before_gc()) {
2614 return false;
2615 }
2616
2617 do_collection_pause_at_safepoint_helper();
2618 return true;
2619 }
2620
2621 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2622 // This summary needs to be printed before incrementing total collections.
2623 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2624 _g1h->total_collections(),
2625 true /* show_thread_times */);
2626 _g1h->print_heap_before_gc();
2627 _g1h->print_heap_regions();
2628 }
2629
2630 G1HeapPrinterMark::~G1HeapPrinterMark() {
2631 _g1h->policy()->print_age_table();
2632 _g1h->rem_set()->print_coarsen_stats();
2633 // We are at the end of the GC. Total collections has already been increased.
2634 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2635 _g1h->total_collections() - 1,
2636 false /* show_thread_times */);
2637
2638 _heap_transition.print();
2639 _g1h->print_heap_regions();
2640 _g1h->print_heap_after_gc();
2641 // Print NUMA statistics.
2642 _g1h->numa()->print_statistics();
2643 }
2644
2645 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2646 _timer(timer), _tracer(tracer) {
2647
2648 _timer->register_gc_start();
2649 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2650 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2651 }
2652
2653 G1JFRTracerMark::~G1JFRTracerMark() {
2654 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2655 _timer->register_gc_end();
2656 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2657 }
2658
2659 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2660 Ticks start = Ticks::now();
2661
2662 _survivor_evac_stats.adjust_desired_plab_size();
2663 _old_evac_stats.adjust_desired_plab_size();
2664
2665 // Start a new incremental collection set for the mutator phase.
2666 start_new_collection_set();
2667 _allocator->init_mutator_alloc_regions();
2668
2669 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2670 }
2671
2672 void G1CollectedHeap::retire_tlabs() {
2673 ensure_parsability(true);
2674 }
2675
2676 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2677 ResourceMark rm;
2678
2679 IsGCActiveMark active_gc_mark;
2680 GCIdMark gc_id_mark;
2681 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2682
2683 GCTraceCPUTime tcpu(_gc_tracer_stw);
2684
2685 _bytes_used_during_gc = 0;
2686
2687 policy()->decide_on_concurrent_start_pause();
2688 // Record whether this pause may need to trigger a concurrent operation. Later,
2689 // when we signal the G1ConcurrentMarkThread, the collector state has already
2690 // been reset for the next pause.
2691 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2692
2693 // Perform the collection.
2694 G1YoungCollector collector(gc_cause());
2695 collector.collect();
2696
2697 // It should now be safe to tell the concurrent mark thread to start
2698 // without its logging output interfering with the logging output
2699 // that came from the pause.
2700 if (should_start_concurrent_mark_operation) {
2701 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2702 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2703 // thread(s) could be running concurrently with us. Make sure that anything
2704 // after this point does not assume that we are the only GC thread running.
2705 // Note: of course, the actual marking work will not start until the safepoint
2706 // itself is released in SuspendibleThreadSet::desynchronize().
2707 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2708 ConcurrentGCBreakpoints::notify_idle_to_active();
2709 }
2710 }
2711
2712 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2713 uint num_workers = workers()->active_workers();
2714 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2715 workers()->run_task(&unlink_task);
2716 }
2717
2718 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2719 assert(obj != NULL, "must not be NULL");
2720 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2721 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2722 // may falsely indicate that this is not the case here: however the collection set only
2723 // contains old regions when concurrent mark is not running.
2724 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2725 }
2726
2727 void G1CollectedHeap::make_pending_list_reachable() {
2728 if (collector_state()->in_concurrent_start_gc()) {
2729 oop pll_head = Universe::reference_pending_list();
2730 if (pll_head != NULL) {
2731 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2732 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2733 }
2734 }
2735 }
2736
2737 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2738 _num_humongous_objects = num_humongous_total;
2739 _num_humongous_reclaim_candidates = num_humongous_candidates;
2740 }
2741
2742 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2743 G1CollectionSetCandidates* candidates = G1CollectedHeap::heap()->collection_set()->candidates();
2744 return candidates != NULL && candidates->num_remaining() > 0;
2745 }
2746
2747 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2748 _collection_set_candidates_card_set_stats = stats;
2749 }
2750
2751 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2752 _young_gen_card_set_stats = stats;
2753 }
2754
2755 void G1CollectedHeap::record_obj_copy_mem_stats() {
2756 policy()->old_gen_alloc_tracker()->
2757 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2758
2759 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2760 create_g1_evac_summary(&_old_evac_stats));
2761 }
2762
2763 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2764 concurrent_mark()->clear_bitmap_for_region(hr);
2765 }
2766
2767 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2768 assert(!hr->is_free(), "the region should not be free");
2769 assert(!hr->is_empty(), "the region should not be empty");
2770 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2771
2772 // Reset region metadata to allow reuse.
2773 hr->hr_clear(true /* clear_space */);
2774 _policy->remset_tracker()->update_at_free(hr);
2775
2776 if (free_list != NULL) {
2777 free_list->add_ordered(hr);
2778 }
2779 }
2780
2781 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2782 FreeRegionList* free_list) {
2783 assert(hr->is_humongous(), "this is only for humongous regions");
2784 hr->clear_humongous();
2785 free_region(hr, free_list);
2786 }
2787
2788 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2789 const uint archive_regions_removed,
2790 const uint humongous_regions_removed) {
2791 if (old_regions_removed > 0 || archive_regions_removed > 0 || humongous_regions_removed > 0) {
2792 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2793 _old_set.bulk_remove(old_regions_removed);
2794 _archive_set.bulk_remove(archive_regions_removed);
2795 _humongous_set.bulk_remove(humongous_regions_removed);
2796 }
2797
2798 }
2799
2800 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2801 assert(list != NULL, "list can't be null");
2802 if (!list->is_empty()) {
2803 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2804 _hrm.insert_list_into_free_list(list);
2805 }
2806 }
2807
2808 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2809 decrease_used(bytes);
2810 }
2811
2812 void G1CollectedHeap::clear_eden() {
2813 _eden.clear();
2814 }
2815
2816 void G1CollectedHeap::clear_collection_set() {
2817 collection_set()->clear();
2818 }
2819
2820 void G1CollectedHeap::rebuild_free_region_list() {
2821 Ticks start = Ticks::now();
2822 _hrm.rebuild_free_list(workers());
2823 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2824 }
2825
2826 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2827 public:
2828 virtual bool do_heap_region(HeapRegion* r) {
2829 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2830 G1CollectedHeap::heap()->clear_region_attr(r);
2831 r->clear_young_index_in_cset();
2832 return false;
2833 }
2834 };
2835
2836 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2837 G1AbandonCollectionSetClosure cl;
2838 collection_set_iterate_all(&cl);
2839
2840 collection_set->clear();
2841 collection_set->stop_incremental_building();
2842 }
2843
2844 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2845 return _allocator->is_retained_old_region(hr);
2846 }
2847
2848 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2849 _eden.add(hr);
2850 _policy->set_region_eden(hr);
2851 }
2852
2853 #ifdef ASSERT
2854
2855 class NoYoungRegionsClosure: public HeapRegionClosure {
2856 private:
2857 bool _success;
2858 public:
2859 NoYoungRegionsClosure() : _success(true) { }
2860 bool do_heap_region(HeapRegion* r) {
2861 if (r->is_young()) {
2862 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2863 p2i(r->bottom()), p2i(r->end()));
2864 _success = false;
2865 }
2866 return false;
2867 }
2868 bool success() { return _success; }
2869 };
2870
2871 bool G1CollectedHeap::check_young_list_empty() {
2872 bool ret = (young_regions_count() == 0);
2873
2874 NoYoungRegionsClosure closure;
2875 heap_region_iterate(&closure);
2876 ret = ret && closure.success();
2877
2878 return ret;
2879 }
2880
2881 #endif // ASSERT
2882
2883 // Remove the given HeapRegion from the appropriate region set.
2884 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2885 if (hr->is_archive()) {
2886 _archive_set.remove(hr);
2887 } else if (hr->is_humongous()) {
2888 _humongous_set.remove(hr);
2889 } else if (hr->is_old()) {
2890 _old_set.remove(hr);
2891 } else if (hr->is_young()) {
2892 // Note that emptying the eden and survivor lists is postponed and instead
2893 // done as the first step when rebuilding the regions sets again. The reason
2894 // for this is that during a full GC string deduplication needs to know if
2895 // a collected region was young or old when the full GC was initiated.
2896 hr->uninstall_surv_rate_group();
2897 } else {
2898 // We ignore free regions, we'll empty the free list afterwards.
2899 assert(hr->is_free(), "it cannot be another type");
2900 }
2901 }
2902
2903 void G1CollectedHeap::increase_used(size_t bytes) {
2904 _summary_bytes_used += bytes;
2905 }
2906
2907 void G1CollectedHeap::decrease_used(size_t bytes) {
2908 assert(_summary_bytes_used >= bytes,
2909 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2910 _summary_bytes_used, bytes);
2911 _summary_bytes_used -= bytes;
2912 }
2913
2914 void G1CollectedHeap::set_used(size_t bytes) {
2915 _summary_bytes_used = bytes;
2916 }
2917
2918 class RebuildRegionSetsClosure : public HeapRegionClosure {
2919 private:
2920 bool _free_list_only;
2921
2922 HeapRegionSet* _old_set;
2923 HeapRegionSet* _archive_set;
2924 HeapRegionSet* _humongous_set;
2925
2926 HeapRegionManager* _hrm;
2927
2928 size_t _total_used;
2929
2930 public:
2931 RebuildRegionSetsClosure(bool free_list_only,
2932 HeapRegionSet* old_set,
2933 HeapRegionSet* archive_set,
2934 HeapRegionSet* humongous_set,
2935 HeapRegionManager* hrm) :
2936 _free_list_only(free_list_only), _old_set(old_set), _archive_set(archive_set),
2937 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2938 assert(_hrm->num_free_regions() == 0, "pre-condition");
2939 if (!free_list_only) {
2940 assert(_old_set->is_empty(), "pre-condition");
2941 assert(_archive_set->is_empty(), "pre-condition");
2942 assert(_humongous_set->is_empty(), "pre-condition");
2943 }
2944 }
2945
2946 bool do_heap_region(HeapRegion* r) {
2947 if (r->is_empty()) {
2948 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2949 // Add free regions to the free list
2950 r->set_free();
2951 _hrm->insert_into_free_list(r);
2952 } else if (!_free_list_only) {
2953 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2954
2955 if (r->is_humongous()) {
2956 _humongous_set->add(r);
2957 } else if (r->is_archive()) {
2958 _archive_set->add(r);
2959 } else {
2960 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2961 // We now move all (non-humongous, non-old, non-archive) regions to old gen,
2962 // and register them as such.
2963 r->move_to_old();
2964 _old_set->add(r);
2965 }
2966 _total_used += r->used();
2967 }
2968
2969 return false;
2970 }
2971
2972 size_t total_used() {
2973 return _total_used;
2974 }
2975 };
2976
2977 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2978 assert_at_safepoint_on_vm_thread();
2979
2980 if (!free_list_only) {
2981 _eden.clear();
2982 _survivor.clear();
2983 }
2984
2985 RebuildRegionSetsClosure cl(free_list_only,
2986 &_old_set, &_archive_set, &_humongous_set,
2987 &_hrm);
2988 heap_region_iterate(&cl);
2989
2990 if (!free_list_only) {
2991 set_used(cl.total_used());
2992 }
2993 assert_used_and_recalculate_used_equal(this);
2994 }
2995
2996 // Methods for the mutator alloc region
2997
2998 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
2999 bool force,
3000 uint node_index) {
3001 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3002 bool should_allocate = policy()->should_allocate_mutator_region();
3003 if (force || should_allocate) {
3004 HeapRegion* new_alloc_region = new_region(word_size,
3005 HeapRegionType::Eden,
3006 false /* do_expand */,
3007 node_index);
3008 if (new_alloc_region != NULL) {
3009 set_region_short_lived_locked(new_alloc_region);
3010 _hr_printer.alloc(new_alloc_region, !should_allocate);
3011 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3012 return new_alloc_region;
3013 }
3014 }
3015 return NULL;
3016 }
3017
3018 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
3019 size_t allocated_bytes) {
3020 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3021 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
3022
3023 collection_set()->add_eden_region(alloc_region);
3024 increase_used(allocated_bytes);
3025 _eden.add_used_bytes(allocated_bytes);
3026 _hr_printer.retire(alloc_region);
3027
3028 // We update the eden sizes here, when the region is retired,
3029 // instead of when it's allocated, since this is the point that its
3030 // used space has been recorded in _summary_bytes_used.
3031 monitoring_support()->update_eden_size();
3032 }
3033
3034 // Methods for the GC alloc regions
3035
3036 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
3037 if (dest.is_old()) {
3038 return true;
3039 } else {
3040 return survivor_regions_count() < policy()->max_survivor_regions();
3041 }
3042 }
3043
3044 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
3045 assert(FreeList_lock->owned_by_self(), "pre-condition");
3046
3047 if (!has_more_regions(dest)) {
3048 return NULL;
3049 }
3050
3051 HeapRegionType type;
3052 if (dest.is_young()) {
3053 type = HeapRegionType::Survivor;
3054 } else {
3055 type = HeapRegionType::Old;
3056 }
3057
3058 HeapRegion* new_alloc_region = new_region(word_size,
3059 type,
3060 true /* do_expand */,
3061 node_index);
3062
3063 if (new_alloc_region != NULL) {
3064 if (type.is_survivor()) {
3065 new_alloc_region->set_survivor();
3066 _survivor.add(new_alloc_region);
3067 register_new_survivor_region_with_region_attr(new_alloc_region);
3068 } else {
3069 new_alloc_region->set_old();
3070 }
3071 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3072 register_region_with_region_attr(new_alloc_region);
3073 _hr_printer.alloc(new_alloc_region);
3074 return new_alloc_region;
3075 }
3076 return NULL;
3077 }
3078
3079 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
3080 size_t allocated_bytes,
3081 G1HeapRegionAttr dest) {
3082 _bytes_used_during_gc += allocated_bytes;
3083 if (dest.is_old()) {
3084 old_set_add(alloc_region);
3085 } else {
3086 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
3087 _survivor.add_used_bytes(allocated_bytes);
3088 }
3089
3090 bool const during_im = collector_state()->in_concurrent_start_gc();
3091 if (during_im && allocated_bytes > 0) {
3092 _cm->add_root_region(alloc_region);
3093 }
3094 _hr_printer.retire(alloc_region);
3095 }
3096
3097 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
3098 bool expanded = false;
3099 uint index = _hrm.find_highest_free(&expanded);
3100
3101 if (index != G1_NO_HRM_INDEX) {
3102 if (expanded) {
3103 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
3104 HeapRegion::GrainWords * HeapWordSize);
3105 }
3106 return _hrm.allocate_free_regions_starting_at(index, 1);
3107 }
3108 return NULL;
3109 }
3110
3111 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
3112 assert(!_cm->is_marked_in_bitmap(obj), "must be");
3113
3114 _cm->raw_mark_in_bitmap(obj);
3115 if (collector_state()->in_concurrent_start_gc()) {
3116 _cm->add_to_liveness(worker_id, obj, obj_size);
3117 }
3118 }
3119
3120 // Optimized nmethod scanning
3121 class RegisterNMethodOopClosure: public OopClosure {
3122 G1CollectedHeap* _g1h;
3123 nmethod* _nm;
3124
3125 public:
3126 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3127 _g1h(g1h), _nm(nm) {}
3128
3129 void do_oop(oop* p) {
3130 oop heap_oop = RawAccess<>::oop_load(p);
3131 if (!CompressedOops::is_null(heap_oop)) {
3132 oop obj = CompressedOops::decode_not_null(heap_oop);
3133 HeapRegion* hr = _g1h->heap_region_containing(obj);
3134 assert(!hr->is_continues_humongous(),
3135 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3136 " starting at " HR_FORMAT,
3137 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3138
3139 // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3140 hr->add_code_root_locked(_nm);
3141 }
3142 }
3143
3144 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3145 };
3146
3147 class UnregisterNMethodOopClosure: public OopClosure {
3148 G1CollectedHeap* _g1h;
3149 nmethod* _nm;
3150
3151 public:
3152 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3153 _g1h(g1h), _nm(nm) {}
3154
3155 void do_oop(oop* p) {
3156 oop heap_oop = RawAccess<>::oop_load(p);
3157 if (!CompressedOops::is_null(heap_oop)) {
3158 oop obj = CompressedOops::decode_not_null(heap_oop);
3159 HeapRegion* hr = _g1h->heap_region_containing(obj);
3160 assert(!hr->is_continues_humongous(),
3161 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3162 " starting at " HR_FORMAT,
3163 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3164
3165 hr->remove_code_root(_nm);
3166 }
3167 }
3168
3169 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3170 };
3171
3172 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3173 guarantee(nm != NULL, "sanity");
3174 RegisterNMethodOopClosure reg_cl(this, nm);
3175 nm->oops_do(®_cl);
3176 }
3177
3178 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3179 guarantee(nm != NULL, "sanity");
3180 UnregisterNMethodOopClosure reg_cl(this, nm);
3181 nm->oops_do(®_cl, true);
3182 }
3183
3184 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3185 if (evacuation_failed) {
3186 // Reset the G1EvacuationFailureALot counters and flags
3187 evac_failure_injector()->reset();
3188
3189 set_used(recalculate_used());
3190 } else {
3191 // The "used" of the collection set have already been subtracted
3192 // when they were freed. Add in the bytes used.
3193 increase_used(_bytes_used_during_gc);
3194 }
3195 }
3196
3197 class RebuildCodeRootClosure: public CodeBlobClosure {
3198 G1CollectedHeap* _g1h;
3199
3200 public:
3201 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3202 _g1h(g1h) {}
3203
3204 void do_code_blob(CodeBlob* cb) {
3205 nmethod* nm = cb->as_nmethod_or_null();
3206 if (nm != NULL) {
3207 _g1h->register_nmethod(nm);
3208 }
3209 }
3210 };
3211
3212 void G1CollectedHeap::rebuild_code_roots() {
3213 RebuildCodeRootClosure blob_cl(this);
3214 CodeCache::blobs_do(&blob_cl);
3215 }
3216
3217 void G1CollectedHeap::initialize_serviceability() {
3218 _monitoring_support->initialize_serviceability();
3219 }
3220
3221 MemoryUsage G1CollectedHeap::memory_usage() {
3222 return _monitoring_support->memory_usage();
3223 }
3224
3225 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3226 return _monitoring_support->memory_managers();
3227 }
3228
3229 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3230 return _monitoring_support->memory_pools();
3231 }
3232
3233 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3234 HeapRegion* region = heap_region_containing(start);
3235 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3236 }
3237
3238 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3239 // We can reach here with an active code cache marking cycle either because the
3240 // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3241 // concurrent start young collection was below the threshold) or aborted. See
3242 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code
3243 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3244 // still have to arm all nmethod entry barriers. They are needed for adding oop
3245 // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3246 if (!CodeCache::is_gc_marking_cycle_active()) {
3247 CodeCache::on_gc_marking_cycle_start();
3248 }
3249 if (concurrent_mark_start) {
3250 CodeCache::arm_all_nmethods();
3251 }
3252 }
3253
3254 void G1CollectedHeap::finish_codecache_marking_cycle() {
3255 CodeCache::on_gc_marking_cycle_finish();
3256 CodeCache::arm_all_nmethods();
3257 }