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/slidingForwarding.inline.hpp"
90 #include "gc/shared/suspendibleThreadSet.hpp"
91 #include "gc/shared/referenceProcessor.inline.hpp"
92 #include "gc/shared/suspendibleThreadSet.hpp"
93 #include "gc/shared/taskqueue.inline.hpp"
94 #include "gc/shared/taskTerminator.hpp"
95 #include "gc/shared/tlab_globals.hpp"
96 #include "gc/shared/workerPolicy.hpp"
97 #include "gc/shared/weakProcessor.inline.hpp"
98 #include "logging/log.hpp"
99 #include "memory/allocation.hpp"
100 #include "memory/heapInspection.hpp"
101 #include "memory/iterator.hpp"
102 #include "memory/metaspaceUtils.hpp"
103 #include "memory/resourceArea.hpp"
104 #include "memory/universe.hpp"
105 #include "oops/access.inline.hpp"
106 #include "oops/compressedOops.inline.hpp"
107 #include "oops/oop.inline.hpp"
108 #include "runtime/atomic.hpp"
109 #include "runtime/handles.inline.hpp"
110 #include "runtime/init.hpp"
111 #include "runtime/java.hpp"
112 #include "runtime/orderAccess.hpp"
113 #include "runtime/threadSMR.hpp"
114 #include "runtime/vmThread.hpp"
115 #include "utilities/align.hpp"
116 #include "utilities/autoRestore.hpp"
117 #include "utilities/bitMap.inline.hpp"
118 #include "utilities/globalDefinitions.hpp"
119 #include "utilities/stack.inline.hpp"
120
121 size_t G1CollectedHeap::_humongous_object_threshold_in_words = 0;
122
123 // INVARIANTS/NOTES
124 //
125 // All allocation activity covered by the G1CollectedHeap interface is
126 // serialized by acquiring the HeapLock. This happens in mem_allocate
127 // and allocate_new_tlab, which are the "entry" points to the
128 // allocation code from the rest of the JVM. (Note that this does not
129 // apply to TLAB allocation, which is not part of this interface: it
130 // is done by clients of this interface.)
131
132 void G1RegionMappingChangedListener::reset_from_card_cache(uint start_idx, size_t num_regions) {
133 HeapRegionRemSet::invalidate_from_card_cache(start_idx, num_regions);
134 }
135
136 void G1RegionMappingChangedListener::on_commit(uint start_idx, size_t num_regions, bool zero_filled) {
137 // The from card cache is not the memory that is actually committed. So we cannot
138 // take advantage of the zero_filled parameter.
139 reset_from_card_cache(start_idx, num_regions);
140 }
141
142 void G1CollectedHeap::run_batch_task(G1BatchedTask* cl) {
143 uint num_workers = MAX2(1u, MIN2(cl->num_workers_estimate(), workers()->active_workers()));
144 cl->set_max_workers(num_workers);
145 workers()->run_task(cl, num_workers);
146 }
147
148 uint G1CollectedHeap::get_chunks_per_region() {
149 uint log_region_size = HeapRegion::LogOfHRGrainBytes;
150 // Limit the expected input values to current known possible values of the
151 // (log) region size. Adjust as necessary after testing if changing the permissible
152 // values for region size.
153 assert(log_region_size >= 20 && log_region_size <= 29,
154 "expected value in [20,29], but got %u", log_region_size);
155 return 1u << (log_region_size / 2 - 4);
156 }
157
158 HeapRegion* G1CollectedHeap::new_heap_region(uint hrs_index,
159 MemRegion mr) {
160 return new HeapRegion(hrs_index, bot(), mr, &_card_set_config);
161 }
162
163 // Private methods.
164
165 HeapRegion* G1CollectedHeap::new_region(size_t word_size,
166 HeapRegionType type,
167 bool do_expand,
168 uint node_index) {
169 assert(!is_humongous(word_size) || word_size <= HeapRegion::GrainWords,
170 "the only time we use this to allocate a humongous region is "
171 "when we are allocating a single humongous region");
172
173 HeapRegion* res = _hrm.allocate_free_region(type, node_index);
174
175 if (res == NULL && do_expand) {
176 // Currently, only attempts to allocate GC alloc regions set
177 // do_expand to true. So, we should only reach here during a
178 // safepoint.
179 assert(SafepointSynchronize::is_at_safepoint(), "invariant");
180
181 log_debug(gc, ergo, heap)("Attempt heap expansion (region allocation request failed). Allocation request: " SIZE_FORMAT "B",
182 word_size * HeapWordSize);
183
184 assert(word_size * HeapWordSize < HeapRegion::GrainBytes,
185 "This kind of expansion should never be more than one region. Size: " SIZE_FORMAT,
186 word_size * HeapWordSize);
187 if (expand_single_region(node_index)) {
188 // Given that expand_single_region() succeeded in expanding the heap, and we
189 // always expand the heap by an amount aligned to the heap
190 // region size, the free list should in theory not be empty.
191 // In either case allocate_free_region() will check for NULL.
192 res = _hrm.allocate_free_region(type, node_index);
193 }
194 }
195 return res;
196 }
197
198 HeapWord*
199 G1CollectedHeap::humongous_obj_allocate_initialize_regions(HeapRegion* first_hr,
200 uint num_regions,
201 size_t word_size) {
202 assert(first_hr != NULL, "pre-condition");
203 assert(is_humongous(word_size), "word_size should be humongous");
204 assert(num_regions * HeapRegion::GrainWords >= word_size, "pre-condition");
205
206 // Index of last region in the series.
207 uint first = first_hr->hrm_index();
208 uint last = first + num_regions - 1;
209
210 // We need to initialize the region(s) we just discovered. This is
211 // a bit tricky given that it can happen concurrently with
212 // refinement threads refining cards on these regions and
213 // potentially wanting to refine the BOT as they are scanning
214 // those cards (this can happen shortly after a cleanup; see CR
215 // 6991377). So we have to set up the region(s) carefully and in
216 // a specific order.
217
218 // The word size sum of all the regions we will allocate.
219 size_t word_size_sum = (size_t) num_regions * HeapRegion::GrainWords;
220 assert(word_size <= word_size_sum, "sanity");
221
222 // The passed in hr will be the "starts humongous" region. The header
223 // of the new object will be placed at the bottom of this region.
224 HeapWord* new_obj = first_hr->bottom();
225 // This will be the new top of the new object.
226 HeapWord* obj_top = new_obj + word_size;
227
228 // First, we need to zero the header of the space that we will be
229 // allocating. When we update top further down, some refinement
230 // threads might try to scan the region. By zeroing the header we
231 // ensure that any thread that will try to scan the region will
232 // come across the zero klass word and bail out.
233 //
234 // NOTE: It would not have been correct to have used
235 // CollectedHeap::fill_with_object() and make the space look like
236 // an int array. The thread that is doing the allocation will
237 // later update the object header to a potentially different array
238 // type and, for a very short period of time, the klass and length
239 // fields will be inconsistent. This could cause a refinement
240 // thread to calculate the object size incorrectly.
241 Copy::fill_to_words(new_obj, oopDesc::header_size(), 0);
242
243 // Next, pad out the unused tail of the last region with filler
244 // objects, for improved usage accounting.
245 // How many words we use for filler objects.
246 size_t word_fill_size = word_size_sum - word_size;
247
248 // How many words memory we "waste" which cannot hold a filler object.
249 size_t words_not_fillable = 0;
250
251 if (word_fill_size >= min_fill_size()) {
252 fill_with_objects(obj_top, word_fill_size);
253 } else if (word_fill_size > 0) {
254 // We have space to fill, but we cannot fit an object there.
255 words_not_fillable = word_fill_size;
256 word_fill_size = 0;
257 }
258
259 // We will set up the first region as "starts humongous". This
260 // will also update the BOT covering all the regions to reflect
261 // that there is a single object that starts at the bottom of the
262 // first region.
263 first_hr->set_starts_humongous(obj_top, word_fill_size);
264 _policy->remset_tracker()->update_at_allocate(first_hr);
265 // Then, if there are any, we will set up the "continues
266 // humongous" regions.
267 HeapRegion* hr = NULL;
268 for (uint i = first + 1; i <= last; ++i) {
269 hr = region_at(i);
270 hr->set_continues_humongous(first_hr);
271 _policy->remset_tracker()->update_at_allocate(hr);
272 }
273
274 // Up to this point no concurrent thread would have been able to
275 // do any scanning on any region in this series. All the top
276 // fields still point to bottom, so the intersection between
277 // [bottom,top] and [card_start,card_end] will be empty. Before we
278 // update the top fields, we'll do a storestore to make sure that
279 // no thread sees the update to top before the zeroing of the
280 // object header and the BOT initialization.
281 OrderAccess::storestore();
282
283 // Now, we will update the top fields of the "continues humongous"
284 // regions except the last one.
285 for (uint i = first; i < last; ++i) {
286 hr = region_at(i);
287 hr->set_top(hr->end());
288 }
289
290 hr = region_at(last);
291 // If we cannot fit a filler object, we must set top to the end
292 // of the humongous object, otherwise we cannot iterate the heap
293 // and the BOT will not be complete.
294 hr->set_top(hr->end() - words_not_fillable);
295
296 assert(hr->bottom() < obj_top && obj_top <= hr->end(),
297 "obj_top should be in last region");
298
299 assert(words_not_fillable == 0 ||
300 first_hr->bottom() + word_size_sum - words_not_fillable == hr->top(),
301 "Miscalculation in humongous allocation");
302
303 increase_used((word_size_sum - words_not_fillable) * HeapWordSize);
304
305 for (uint i = first; i <= last; ++i) {
306 hr = region_at(i);
307 _humongous_set.add(hr);
308 _hr_printer.alloc(hr);
309 }
310
311 return new_obj;
312 }
313
314 size_t G1CollectedHeap::humongous_obj_size_in_regions(size_t word_size) {
315 assert(is_humongous(word_size), "Object of size " SIZE_FORMAT " must be humongous here", word_size);
316 return align_up(word_size, HeapRegion::GrainWords) / HeapRegion::GrainWords;
317 }
318
319 // If could fit into free regions w/o expansion, try.
320 // Otherwise, if can expand, do so.
321 // Otherwise, if using ex regions might help, try with ex given back.
322 HeapWord* G1CollectedHeap::humongous_obj_allocate(size_t word_size) {
323 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
324
325 _verifier->verify_region_sets_optional();
326
327 uint obj_regions = (uint) humongous_obj_size_in_regions(word_size);
328
329 // Policy: First try to allocate a humongous object in the free list.
330 HeapRegion* humongous_start = _hrm.allocate_humongous(obj_regions);
331 if (humongous_start == NULL) {
332 // Policy: We could not find enough regions for the humongous object in the
333 // free list. Look through the heap to find a mix of free and uncommitted regions.
334 // If so, expand the heap and allocate the humongous object.
335 humongous_start = _hrm.expand_and_allocate_humongous(obj_regions);
336 if (humongous_start != NULL) {
337 // We managed to find a region by expanding the heap.
338 log_debug(gc, ergo, heap)("Heap expansion (humongous allocation request). Allocation request: " SIZE_FORMAT "B",
339 word_size * HeapWordSize);
340 policy()->record_new_heap_size(num_regions());
341 } else {
342 // Policy: Potentially trigger a defragmentation GC.
343 }
344 }
345
346 HeapWord* result = NULL;
347 if (humongous_start != NULL) {
348 result = humongous_obj_allocate_initialize_regions(humongous_start, obj_regions, word_size);
349 assert(result != NULL, "it should always return a valid result");
350
351 // A successful humongous object allocation changes the used space
352 // information of the old generation so we need to recalculate the
353 // sizes and update the jstat counters here.
354 monitoring_support()->update_sizes();
355 }
356
357 _verifier->verify_region_sets_optional();
358
359 return result;
360 }
361
362 HeapWord* G1CollectedHeap::allocate_new_tlab(size_t min_size,
363 size_t requested_size,
364 size_t* actual_size) {
365 assert_heap_not_locked_and_not_at_safepoint();
366 assert(!is_humongous(requested_size), "we do not allow humongous TLABs");
367
368 return attempt_allocation(min_size, requested_size, actual_size);
369 }
370
371 HeapWord*
372 G1CollectedHeap::mem_allocate(size_t word_size,
373 bool* gc_overhead_limit_was_exceeded) {
374 assert_heap_not_locked_and_not_at_safepoint();
375
376 if (is_humongous(word_size)) {
377 return attempt_allocation_humongous(word_size);
378 }
379 size_t dummy = 0;
380 return attempt_allocation(word_size, word_size, &dummy);
381 }
382
383 HeapWord* G1CollectedHeap::attempt_allocation_slow(size_t word_size) {
384 ResourceMark rm; // For retrieving the thread names in log messages.
385
386 // Make sure you read the note in attempt_allocation_humongous().
387
388 assert_heap_not_locked_and_not_at_safepoint();
389 assert(!is_humongous(word_size), "attempt_allocation_slow() should not "
390 "be called for humongous allocation requests");
391
392 // We should only get here after the first-level allocation attempt
393 // (attempt_allocation()) failed to allocate.
394
395 // We will loop until a) we manage to successfully perform the
396 // allocation or b) we successfully schedule a collection which
397 // fails to perform the allocation. b) is the only case when we'll
398 // return NULL.
399 HeapWord* result = NULL;
400 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
401 bool should_try_gc;
402 uint gc_count_before;
403
404 {
405 MutexLocker x(Heap_lock);
406
407 // Now that we have the lock, we first retry the allocation in case another
408 // thread changed the region while we were waiting to acquire the lock.
409 result = _allocator->attempt_allocation_locked(word_size);
410 if (result != NULL) {
411 return result;
412 }
413
414 // If the GCLocker is active and we are bound for a GC, try expanding young gen.
415 // This is different to when only GCLocker::needs_gc() is set: try to avoid
416 // waiting because the GCLocker is active to not wait too long.
417 if (GCLocker::is_active_and_needs_gc() && policy()->can_expand_young_list()) {
418 // No need for an ergo message here, can_expand_young_list() does this when
419 // it returns true.
420 result = _allocator->attempt_allocation_force(word_size);
421 if (result != NULL) {
422 return result;
423 }
424 }
425
426 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
427 // the GCLocker initiated GC has been performed and then retry. This includes
428 // the case when the GC Locker is not active but has not been performed.
429 should_try_gc = !GCLocker::needs_gc();
430 // Read the GC count while still holding the Heap_lock.
431 gc_count_before = total_collections();
432 }
433
434 if (should_try_gc) {
435 bool succeeded;
436 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_inc_collection_pause);
437 if (result != NULL) {
438 assert(succeeded, "only way to get back a non-NULL result");
439 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
440 Thread::current()->name(), p2i(result));
441 return result;
442 }
443
444 if (succeeded) {
445 // We successfully scheduled a collection which failed to allocate. No
446 // point in trying to allocate further. We'll just return NULL.
447 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
448 SIZE_FORMAT " words", Thread::current()->name(), word_size);
449 return NULL;
450 }
451 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT " words",
452 Thread::current()->name(), word_size);
453 } else {
454 // Failed to schedule a collection.
455 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
456 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
457 SIZE_FORMAT " words", Thread::current()->name(), word_size);
458 return NULL;
459 }
460 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
461 // The GCLocker is either active or the GCLocker initiated
462 // GC has not yet been performed. Stall until it is and
463 // then retry the allocation.
464 GCLocker::stall_until_clear();
465 gclocker_retry_count += 1;
466 }
467
468 // We can reach here if we were unsuccessful in scheduling a
469 // collection (because another thread beat us to it) or if we were
470 // stalled due to the GC locker. In either can we should retry the
471 // allocation attempt in case another thread successfully
472 // performed a collection and reclaimed enough space. We do the
473 // first attempt (without holding the Heap_lock) here and the
474 // follow-on attempt will be at the start of the next loop
475 // iteration (after taking the Heap_lock).
476 size_t dummy = 0;
477 result = _allocator->attempt_allocation(word_size, word_size, &dummy);
478 if (result != NULL) {
479 return result;
480 }
481
482 // Give a warning if we seem to be looping forever.
483 if ((QueuedAllocationWarningCount > 0) &&
484 (try_count % QueuedAllocationWarningCount == 0)) {
485 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
486 Thread::current()->name(), try_count, word_size);
487 }
488 }
489
490 ShouldNotReachHere();
491 return NULL;
492 }
493
494 bool G1CollectedHeap::check_archive_addresses(MemRegion* ranges, size_t count) {
495 assert(ranges != NULL, "MemRegion array NULL");
496 assert(count != 0, "No MemRegions provided");
497 MemRegion reserved = _hrm.reserved();
498 for (size_t i = 0; i < count; i++) {
499 if (!reserved.contains(ranges[i].start()) || !reserved.contains(ranges[i].last())) {
500 return false;
501 }
502 }
503 return true;
504 }
505
506 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges,
507 size_t count,
508 bool open) {
509 assert(!is_init_completed(), "Expect to be called at JVM init time");
510 assert(ranges != NULL, "MemRegion array NULL");
511 assert(count != 0, "No MemRegions provided");
512 MutexLocker x(Heap_lock);
513
514 MemRegion reserved = _hrm.reserved();
515 HeapWord* prev_last_addr = NULL;
516 HeapRegion* prev_last_region = NULL;
517
518 // Temporarily disable pretouching of heap pages. This interface is used
519 // when mmap'ing archived heap data in, so pre-touching is wasted.
520 FlagSetting fs(AlwaysPreTouch, false);
521
522 // For each specified MemRegion range, allocate the corresponding G1
523 // regions and mark them as archive regions. We expect the ranges
524 // in ascending starting address order, without overlap.
525 for (size_t i = 0; i < count; i++) {
526 MemRegion curr_range = ranges[i];
527 HeapWord* start_address = curr_range.start();
528 size_t word_size = curr_range.word_size();
529 HeapWord* last_address = curr_range.last();
530 size_t commits = 0;
531
532 guarantee(reserved.contains(start_address) && reserved.contains(last_address),
533 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
534 p2i(start_address), p2i(last_address));
535 guarantee(start_address > prev_last_addr,
536 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
537 p2i(start_address), p2i(prev_last_addr));
538 prev_last_addr = last_address;
539
540 // Check for ranges that start in the same G1 region in which the previous
541 // range ended, and adjust the start address so we don't try to allocate
542 // the same region again. If the current range is entirely within that
543 // region, skip it, just adjusting the recorded top.
544 HeapRegion* start_region = _hrm.addr_to_region(start_address);
545 if ((prev_last_region != NULL) && (start_region == prev_last_region)) {
546 start_address = start_region->end();
547 if (start_address > last_address) {
548 increase_used(word_size * HeapWordSize);
549 start_region->set_top(last_address + 1);
550 continue;
551 }
552 start_region->set_top(start_address);
553 curr_range = MemRegion(start_address, last_address + 1);
554 start_region = _hrm.addr_to_region(start_address);
555 }
556
557 // Perform the actual region allocation, exiting if it fails.
558 // Then note how much new space we have allocated.
559 if (!_hrm.allocate_containing_regions(curr_range, &commits, workers())) {
560 return false;
561 }
562 increase_used(word_size * HeapWordSize);
563 if (commits != 0) {
564 log_debug(gc, ergo, heap)("Attempt heap expansion (allocate archive regions). Total size: " SIZE_FORMAT "B",
565 HeapRegion::GrainWords * HeapWordSize * commits);
566
567 }
568
569 // Mark each G1 region touched by the range as archive, add it to
570 // the old set, and set top.
571 HeapRegion* curr_region = _hrm.addr_to_region(start_address);
572 HeapRegion* last_region = _hrm.addr_to_region(last_address);
573 prev_last_region = last_region;
574
575 while (curr_region != NULL) {
576 assert(curr_region->is_empty() && !curr_region->is_pinned(),
577 "Region already in use (index %u)", curr_region->hrm_index());
578 if (open) {
579 curr_region->set_open_archive();
580 } else {
581 curr_region->set_closed_archive();
582 }
583 _hr_printer.alloc(curr_region);
584 _archive_set.add(curr_region);
585 HeapWord* top;
586 HeapRegion* next_region;
587 if (curr_region != last_region) {
588 top = curr_region->end();
589 next_region = _hrm.next_region_in_heap(curr_region);
590 } else {
591 top = last_address + 1;
592 next_region = NULL;
593 }
594 curr_region->set_top(top);
595 curr_region = next_region;
596 }
597 }
598 return true;
599 }
600
601 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
602 assert(!is_init_completed(), "Expect to be called at JVM init time");
603 assert(ranges != NULL, "MemRegion array NULL");
604 assert(count != 0, "No MemRegions provided");
605 MemRegion reserved = _hrm.reserved();
606 HeapWord *prev_last_addr = NULL;
607 HeapRegion* prev_last_region = NULL;
608
609 // For each MemRegion, create filler objects, if needed, in the G1 regions
610 // that contain the address range. The address range actually within the
611 // MemRegion will not be modified. That is assumed to have been initialized
612 // elsewhere, probably via an mmap of archived heap data.
613 MutexLocker x(Heap_lock);
614 for (size_t i = 0; i < count; i++) {
615 HeapWord* start_address = ranges[i].start();
616 HeapWord* last_address = ranges[i].last();
617
618 assert(reserved.contains(start_address) && reserved.contains(last_address),
619 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
620 p2i(start_address), p2i(last_address));
621 assert(start_address > prev_last_addr,
622 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
623 p2i(start_address), p2i(prev_last_addr));
624
625 HeapRegion* start_region = _hrm.addr_to_region(start_address);
626 HeapRegion* last_region = _hrm.addr_to_region(last_address);
627 HeapWord* bottom_address = start_region->bottom();
628
629 // Check for a range beginning in the same region in which the
630 // previous one ended.
631 if (start_region == prev_last_region) {
632 bottom_address = prev_last_addr + 1;
633 }
634
635 // Verify that the regions were all marked as archive regions by
636 // alloc_archive_regions.
637 HeapRegion* curr_region = start_region;
638 while (curr_region != NULL) {
639 guarantee(curr_region->is_archive(),
640 "Expected archive region at index %u", curr_region->hrm_index());
641 if (curr_region != last_region) {
642 curr_region = _hrm.next_region_in_heap(curr_region);
643 } else {
644 curr_region = NULL;
645 }
646 }
647
648 prev_last_addr = last_address;
649 prev_last_region = last_region;
650
651 // Fill the memory below the allocated range with dummy object(s),
652 // if the region bottom does not match the range start, or if the previous
653 // range ended within the same G1 region, and there is a gap.
654 assert(start_address >= bottom_address, "bottom address should not be greater than start address");
655 if (start_address > bottom_address) {
656 size_t fill_size = pointer_delta(start_address, bottom_address);
657 G1CollectedHeap::fill_with_objects(bottom_address, fill_size);
658 increase_used(fill_size * HeapWordSize);
659 }
660 }
661 }
662
663 inline HeapWord* G1CollectedHeap::attempt_allocation(size_t min_word_size,
664 size_t desired_word_size,
665 size_t* actual_word_size) {
666 assert_heap_not_locked_and_not_at_safepoint();
667 assert(!is_humongous(desired_word_size), "attempt_allocation() should not "
668 "be called for humongous allocation requests");
669
670 HeapWord* result = _allocator->attempt_allocation(min_word_size, desired_word_size, actual_word_size);
671
672 if (result == NULL) {
673 *actual_word_size = desired_word_size;
674 result = attempt_allocation_slow(desired_word_size);
675 }
676
677 assert_heap_not_locked();
678 if (result != NULL) {
679 assert(*actual_word_size != 0, "Actual size must have been set here");
680 dirty_young_block(result, *actual_word_size);
681 } else {
682 *actual_word_size = 0;
683 }
684
685 return result;
686 }
687
688 void G1CollectedHeap::populate_archive_regions_bot_part(MemRegion* ranges, size_t count) {
689 assert(!is_init_completed(), "Expect to be called at JVM init time");
690 assert(ranges != NULL, "MemRegion array NULL");
691 assert(count != 0, "No MemRegions provided");
692
693 HeapWord* st = ranges[0].start();
694 HeapWord* last = ranges[count-1].last();
695 HeapRegion* hr_st = _hrm.addr_to_region(st);
696 HeapRegion* hr_last = _hrm.addr_to_region(last);
697
698 HeapRegion* hr_curr = hr_st;
699 while (hr_curr != NULL) {
700 hr_curr->update_bot();
701 if (hr_curr != hr_last) {
702 hr_curr = _hrm.next_region_in_heap(hr_curr);
703 } else {
704 hr_curr = NULL;
705 }
706 }
707 }
708
709 void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
710 assert(!is_init_completed(), "Expect to be called at JVM init time");
711 assert(ranges != NULL, "MemRegion array NULL");
712 assert(count != 0, "No MemRegions provided");
713 MemRegion reserved = _hrm.reserved();
714 HeapWord* prev_last_addr = NULL;
715 HeapRegion* prev_last_region = NULL;
716 size_t size_used = 0;
717 uint shrink_count = 0;
718
719 // For each Memregion, free the G1 regions that constitute it, and
720 // notify mark-sweep that the range is no longer to be considered 'archive.'
721 MutexLocker x(Heap_lock);
722 for (size_t i = 0; i < count; i++) {
723 HeapWord* start_address = ranges[i].start();
724 HeapWord* last_address = ranges[i].last();
725
726 assert(reserved.contains(start_address) && reserved.contains(last_address),
727 "MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
728 p2i(start_address), p2i(last_address));
729 assert(start_address > prev_last_addr,
730 "Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
731 p2i(start_address), p2i(prev_last_addr));
732 size_used += ranges[i].byte_size();
733 prev_last_addr = last_address;
734
735 HeapRegion* start_region = _hrm.addr_to_region(start_address);
736 HeapRegion* last_region = _hrm.addr_to_region(last_address);
737
738 // Check for ranges that start in the same G1 region in which the previous
739 // range ended, and adjust the start address so we don't try to free
740 // the same region again. If the current range is entirely within that
741 // region, skip it.
742 if (start_region == prev_last_region) {
743 start_address = start_region->end();
744 if (start_address > last_address) {
745 continue;
746 }
747 start_region = _hrm.addr_to_region(start_address);
748 }
749 prev_last_region = last_region;
750
751 // After verifying that each region was marked as an archive region by
752 // alloc_archive_regions, set it free and empty and uncommit it.
753 HeapRegion* curr_region = start_region;
754 while (curr_region != NULL) {
755 guarantee(curr_region->is_archive(),
756 "Expected archive region at index %u", curr_region->hrm_index());
757 uint curr_index = curr_region->hrm_index();
758 _archive_set.remove(curr_region);
759 curr_region->set_free();
760 curr_region->set_top(curr_region->bottom());
761 if (curr_region != last_region) {
762 curr_region = _hrm.next_region_in_heap(curr_region);
763 } else {
764 curr_region = NULL;
765 }
766
767 _hrm.shrink_at(curr_index, 1);
768 shrink_count++;
769 }
770 }
771
772 if (shrink_count != 0) {
773 log_debug(gc, ergo, heap)("Attempt heap shrinking (archive regions). Total size: " SIZE_FORMAT "B",
774 HeapRegion::GrainWords * HeapWordSize * shrink_count);
775 // Explicit uncommit.
776 uncommit_regions(shrink_count);
777 }
778 decrease_used(size_used);
779 }
780
781 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size) {
782 ResourceMark rm; // For retrieving the thread names in log messages.
783
784 // The structure of this method has a lot of similarities to
785 // attempt_allocation_slow(). The reason these two were not merged
786 // into a single one is that such a method would require several "if
787 // allocation is not humongous do this, otherwise do that"
788 // conditional paths which would obscure its flow. In fact, an early
789 // version of this code did use a unified method which was harder to
790 // follow and, as a result, it had subtle bugs that were hard to
791 // track down. So keeping these two methods separate allows each to
792 // be more readable. It will be good to keep these two in sync as
793 // much as possible.
794
795 assert_heap_not_locked_and_not_at_safepoint();
796 assert(is_humongous(word_size), "attempt_allocation_humongous() "
797 "should only be called for humongous allocations");
798
799 // Humongous objects can exhaust the heap quickly, so we should check if we
800 // need to start a marking cycle at each humongous object allocation. We do
801 // the check before we do the actual allocation. The reason for doing it
802 // before the allocation is that we avoid having to keep track of the newly
803 // allocated memory while we do a GC.
804 if (policy()->need_to_start_conc_mark("concurrent humongous allocation",
805 word_size)) {
806 collect(GCCause::_g1_humongous_allocation);
807 }
808
809 // We will loop until a) we manage to successfully perform the
810 // allocation or b) we successfully schedule a collection which
811 // fails to perform the allocation. b) is the only case when we'll
812 // return NULL.
813 HeapWord* result = NULL;
814 for (uint try_count = 1, gclocker_retry_count = 0; /* we'll return */; try_count += 1) {
815 bool should_try_gc;
816 uint gc_count_before;
817
818
819 {
820 MutexLocker x(Heap_lock);
821
822 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
823 // Given that humongous objects are not allocated in young
824 // regions, we'll first try to do the allocation without doing a
825 // collection hoping that there's enough space in the heap.
826 result = humongous_obj_allocate(word_size);
827 if (result != NULL) {
828 policy()->old_gen_alloc_tracker()->
829 add_allocated_humongous_bytes_since_last_gc(size_in_regions * HeapRegion::GrainBytes);
830 return result;
831 }
832
833 // Only try a GC if the GCLocker does not signal the need for a GC. Wait until
834 // the GCLocker initiated GC has been performed and then retry. This includes
835 // the case when the GC Locker is not active but has not been performed.
836 should_try_gc = !GCLocker::needs_gc();
837 // Read the GC count while still holding the Heap_lock.
838 gc_count_before = total_collections();
839 }
840
841 if (should_try_gc) {
842 bool succeeded;
843 result = do_collection_pause(word_size, gc_count_before, &succeeded, GCCause::_g1_humongous_allocation);
844 if (result != NULL) {
845 assert(succeeded, "only way to get back a non-NULL result");
846 log_trace(gc, alloc)("%s: Successfully scheduled collection returning " PTR_FORMAT,
847 Thread::current()->name(), p2i(result));
848 size_t size_in_regions = humongous_obj_size_in_regions(word_size);
849 policy()->old_gen_alloc_tracker()->
850 record_collection_pause_humongous_allocation(size_in_regions * HeapRegion::GrainBytes);
851 return result;
852 }
853
854 if (succeeded) {
855 // We successfully scheduled a collection which failed to allocate. No
856 // point in trying to allocate further. We'll just return NULL.
857 log_trace(gc, alloc)("%s: Successfully scheduled collection failing to allocate "
858 SIZE_FORMAT " words", Thread::current()->name(), word_size);
859 return NULL;
860 }
861 log_trace(gc, alloc)("%s: Unsuccessfully scheduled collection allocating " SIZE_FORMAT "",
862 Thread::current()->name(), word_size);
863 } else {
864 // Failed to schedule a collection.
865 if (gclocker_retry_count > GCLockerRetryAllocationCount) {
866 log_warning(gc, alloc)("%s: Retried waiting for GCLocker too often allocating "
867 SIZE_FORMAT " words", Thread::current()->name(), word_size);
868 return NULL;
869 }
870 log_trace(gc, alloc)("%s: Stall until clear", Thread::current()->name());
871 // The GCLocker is either active or the GCLocker initiated
872 // GC has not yet been performed. Stall until it is and
873 // then retry the allocation.
874 GCLocker::stall_until_clear();
875 gclocker_retry_count += 1;
876 }
877
878
879 // We can reach here if we were unsuccessful in scheduling a
880 // collection (because another thread beat us to it) or if we were
881 // stalled due to the GC locker. In either can we should retry the
882 // allocation attempt in case another thread successfully
883 // performed a collection and reclaimed enough space.
884 // Humongous object allocation always needs a lock, so we wait for the retry
885 // in the next iteration of the loop, unlike for the regular iteration case.
886 // Give a warning if we seem to be looping forever.
887
888 if ((QueuedAllocationWarningCount > 0) &&
889 (try_count % QueuedAllocationWarningCount == 0)) {
890 log_warning(gc, alloc)("%s: Retried allocation %u times for " SIZE_FORMAT " words",
891 Thread::current()->name(), try_count, word_size);
892 }
893 }
894
895 ShouldNotReachHere();
896 return NULL;
897 }
898
899 HeapWord* G1CollectedHeap::attempt_allocation_at_safepoint(size_t word_size,
900 bool expect_null_mutator_alloc_region) {
901 assert_at_safepoint_on_vm_thread();
902 assert(!_allocator->has_mutator_alloc_region() || !expect_null_mutator_alloc_region,
903 "the current alloc region was unexpectedly found to be non-NULL");
904
905 if (!is_humongous(word_size)) {
906 return _allocator->attempt_allocation_locked(word_size);
907 } else {
908 HeapWord* result = humongous_obj_allocate(word_size);
909 if (result != NULL && policy()->need_to_start_conc_mark("STW humongous allocation")) {
910 collector_state()->set_initiate_conc_mark_if_possible(true);
911 }
912 return result;
913 }
914
915 ShouldNotReachHere();
916 }
917
918 class PostCompactionPrinterClosure: public HeapRegionClosure {
919 private:
920 G1HRPrinter* _hr_printer;
921 public:
922 bool do_heap_region(HeapRegion* hr) {
923 assert(!hr->is_young(), "not expecting to find young regions");
924 _hr_printer->post_compaction(hr);
925 return false;
926 }
927
928 PostCompactionPrinterClosure(G1HRPrinter* hr_printer)
929 : _hr_printer(hr_printer) { }
930 };
931
932 void G1CollectedHeap::print_heap_after_full_collection() {
933 // Post collection region logging.
934 // We should do this after we potentially resize the heap so
935 // that all the COMMIT / UNCOMMIT events are generated before
936 // the compaction events.
937 if (_hr_printer.is_active()) {
938 PostCompactionPrinterClosure cl(hr_printer());
939 heap_region_iterate(&cl);
940 }
941 }
942
943 bool G1CollectedHeap::abort_concurrent_cycle() {
944 // Disable discovery and empty the discovered lists
945 // for the CM ref processor.
946 _ref_processor_cm->disable_discovery();
947 _ref_processor_cm->abandon_partial_discovery();
948 _ref_processor_cm->verify_no_references_recorded();
949
950 // Abandon current iterations of concurrent marking and concurrent
951 // refinement, if any are in progress.
952 return concurrent_mark()->concurrent_cycle_abort();
953 }
954
955 void G1CollectedHeap::prepare_heap_for_full_collection() {
956 // Make sure we'll choose a new allocation region afterwards.
957 _allocator->release_mutator_alloc_regions();
958 _allocator->abandon_gc_alloc_regions();
959
960 // We may have added regions to the current incremental collection
961 // set between the last GC or pause and now. We need to clear the
962 // incremental collection set and then start rebuilding it afresh
963 // after this full GC.
964 abandon_collection_set(collection_set());
965
966 _hrm.remove_all_free_regions();
967 }
968
969 void G1CollectedHeap::verify_before_full_collection(bool explicit_gc) {
970 assert(!GCCause::is_user_requested_gc(gc_cause()) || explicit_gc, "invariant");
971 assert_used_and_recalculate_used_equal(this);
972 if (!VerifyBeforeGC) {
973 return;
974 }
975 _verifier->verify_region_sets_optional();
976 _verifier->verify_before_gc(G1HeapVerifier::G1VerifyFull);
977 _verifier->verify_bitmap_clear(true /* above_tams_only */);
978 }
979
980 void G1CollectedHeap::prepare_for_mutator_after_full_collection() {
981 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
982 ClassLoaderDataGraph::purge(/*at_safepoint*/true);
983 DEBUG_ONLY(MetaspaceUtils::verify();)
984
985 // Prepare heap for normal collections.
986 assert(num_free_regions() == 0, "we should not have added any free regions");
987 rebuild_region_sets(false /* free_list_only */);
988 abort_refinement();
989 resize_heap_if_necessary();
990 uncommit_regions_if_necessary();
991
992 // Rebuild the code root lists for each region
993 rebuild_code_roots();
994
995 start_new_collection_set();
996 _allocator->init_mutator_alloc_regions();
997
998 // Post collection state updates.
999 MetaspaceGC::compute_new_size();
1000 }
1001
1002 void G1CollectedHeap::abort_refinement() {
1003 // Discard all remembered set updates and reset refinement statistics.
1004 G1BarrierSet::dirty_card_queue_set().abandon_logs_and_stats();
1005 assert(G1BarrierSet::dirty_card_queue_set().num_cards() == 0,
1006 "DCQS should be empty");
1007 concurrent_refine()->get_and_reset_refinement_stats();
1008 }
1009
1010 void G1CollectedHeap::verify_after_full_collection() {
1011 if (!VerifyAfterGC) {
1012 return;
1013 }
1014 _hrm.verify_optional();
1015 _verifier->verify_region_sets_optional();
1016 _verifier->verify_after_gc(G1HeapVerifier::G1VerifyFull);
1017 _verifier->verify_bitmap_clear(false /* above_tams_only */);
1018
1019 // At this point there should be no regions in the
1020 // entire heap tagged as young.
1021 assert(check_young_list_empty(), "young list should be empty at this point");
1022
1023 // Note: since we've just done a full GC, concurrent
1024 // marking is no longer active. Therefore we need not
1025 // re-enable reference discovery for the CM ref processor.
1026 // That will be done at the start of the next marking cycle.
1027 // We also know that the STW processor should no longer
1028 // discover any new references.
1029 assert(!_ref_processor_stw->discovery_enabled(), "Postcondition");
1030 assert(!_ref_processor_cm->discovery_enabled(), "Postcondition");
1031 _ref_processor_stw->verify_no_references_recorded();
1032 _ref_processor_cm->verify_no_references_recorded();
1033 }
1034
1035 bool G1CollectedHeap::do_full_collection(bool explicit_gc,
1036 bool clear_all_soft_refs,
1037 bool do_maximal_compaction) {
1038 assert_at_safepoint_on_vm_thread();
1039
1040 if (GCLocker::check_active_before_gc()) {
1041 // Full GC was not completed.
1042 return false;
1043 }
1044
1045 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
1046 soft_ref_policy()->should_clear_all_soft_refs();
1047
1048 G1FullGCMark gc_mark;
1049 GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause(), true);
1050 G1FullCollector collector(this, explicit_gc, do_clear_all_soft_refs, do_maximal_compaction, gc_mark.tracer());
1051
1052 collector.prepare_collection();
1053 collector.collect();
1054 collector.complete_collection();
1055
1056 // Full collection was successfully completed.
1057 return true;
1058 }
1059
1060 void G1CollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1061 // Currently, there is no facility in the do_full_collection(bool) API to notify
1062 // the caller that the collection did not succeed (e.g., because it was locked
1063 // out by the GC locker). So, right now, we'll ignore the return value.
1064 // When clear_all_soft_refs is set we want to do a maximal compaction
1065 // not leaving any dead wood.
1066 bool do_maximal_compaction = clear_all_soft_refs;
1067 bool dummy = do_full_collection(true, /* explicit_gc */
1068 clear_all_soft_refs,
1069 do_maximal_compaction);
1070 }
1071
1072 bool G1CollectedHeap::upgrade_to_full_collection() {
1073 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1074 log_info(gc, ergo)("Attempting full compaction clearing soft references");
1075 bool success = do_full_collection(false /* explicit gc */,
1076 true /* clear_all_soft_refs */,
1077 false /* do_maximal_compaction */);
1078 // do_full_collection only fails if blocked by GC locker and that can't
1079 // be the case here since we only call this when already completed one gc.
1080 assert(success, "invariant");
1081 return success;
1082 }
1083
1084 void G1CollectedHeap::resize_heap_if_necessary() {
1085 assert_at_safepoint_on_vm_thread();
1086
1087 bool should_expand;
1088 size_t resize_amount = _heap_sizing_policy->full_collection_resize_amount(should_expand);
1089
1090 if (resize_amount == 0) {
1091 return;
1092 } else if (should_expand) {
1093 expand(resize_amount, _workers);
1094 } else {
1095 shrink(resize_amount);
1096 }
1097 }
1098
1099 HeapWord* G1CollectedHeap::satisfy_failed_allocation_helper(size_t word_size,
1100 bool do_gc,
1101 bool maximal_compaction,
1102 bool expect_null_mutator_alloc_region,
1103 bool* gc_succeeded) {
1104 *gc_succeeded = true;
1105 // Let's attempt the allocation first.
1106 HeapWord* result =
1107 attempt_allocation_at_safepoint(word_size,
1108 expect_null_mutator_alloc_region);
1109 if (result != NULL) {
1110 return result;
1111 }
1112
1113 // In a G1 heap, we're supposed to keep allocation from failing by
1114 // incremental pauses. Therefore, at least for now, we'll favor
1115 // expansion over collection. (This might change in the future if we can
1116 // do something smarter than full collection to satisfy a failed alloc.)
1117 result = expand_and_allocate(word_size);
1118 if (result != NULL) {
1119 return result;
1120 }
1121
1122 if (do_gc) {
1123 GCCauseSetter compaction(this, GCCause::_g1_compaction_pause);
1124 // Expansion didn't work, we'll try to do a Full GC.
1125 // If maximal_compaction is set we clear all soft references and don't
1126 // allow any dead wood to be left on the heap.
1127 if (maximal_compaction) {
1128 log_info(gc, ergo)("Attempting maximal full compaction clearing soft references");
1129 } else {
1130 log_info(gc, ergo)("Attempting full compaction");
1131 }
1132 *gc_succeeded = do_full_collection(false, /* explicit_gc */
1133 maximal_compaction /* clear_all_soft_refs */ ,
1134 maximal_compaction /* do_maximal_compaction */);
1135 }
1136
1137 return NULL;
1138 }
1139
1140 HeapWord* G1CollectedHeap::satisfy_failed_allocation(size_t word_size,
1141 bool* succeeded) {
1142 assert_at_safepoint_on_vm_thread();
1143
1144 // Attempts to allocate followed by Full GC.
1145 HeapWord* result =
1146 satisfy_failed_allocation_helper(word_size,
1147 true, /* do_gc */
1148 false, /* maximum_collection */
1149 false, /* expect_null_mutator_alloc_region */
1150 succeeded);
1151
1152 if (result != NULL || !*succeeded) {
1153 return result;
1154 }
1155
1156 // Attempts to allocate followed by Full GC that will collect all soft references.
1157 result = satisfy_failed_allocation_helper(word_size,
1158 true, /* do_gc */
1159 true, /* maximum_collection */
1160 true, /* expect_null_mutator_alloc_region */
1161 succeeded);
1162
1163 if (result != NULL || !*succeeded) {
1164 return result;
1165 }
1166
1167 // Attempts to allocate, no GC
1168 result = satisfy_failed_allocation_helper(word_size,
1169 false, /* do_gc */
1170 false, /* maximum_collection */
1171 true, /* expect_null_mutator_alloc_region */
1172 succeeded);
1173
1174 if (result != NULL) {
1175 return result;
1176 }
1177
1178 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
1179 "Flag should have been handled and cleared prior to this point");
1180
1181 // What else? We might try synchronous finalization later. If the total
1182 // space available is large enough for the allocation, then a more
1183 // complete compaction phase than we've tried so far might be
1184 // appropriate.
1185 return NULL;
1186 }
1187
1188 // Attempting to expand the heap sufficiently
1189 // to support an allocation of the given "word_size". If
1190 // successful, perform the allocation and return the address of the
1191 // allocated block, or else "NULL".
1192
1193 HeapWord* G1CollectedHeap::expand_and_allocate(size_t word_size) {
1194 assert_at_safepoint_on_vm_thread();
1195
1196 _verifier->verify_region_sets_optional();
1197
1198 size_t expand_bytes = MAX2(word_size * HeapWordSize, MinHeapDeltaBytes);
1199 log_debug(gc, ergo, heap)("Attempt heap expansion (allocation request failed). Allocation request: " SIZE_FORMAT "B",
1200 word_size * HeapWordSize);
1201
1202
1203 if (expand(expand_bytes, _workers)) {
1204 _hrm.verify_optional();
1205 _verifier->verify_region_sets_optional();
1206 return attempt_allocation_at_safepoint(word_size,
1207 false /* expect_null_mutator_alloc_region */);
1208 }
1209 return NULL;
1210 }
1211
1212 bool G1CollectedHeap::expand(size_t expand_bytes, WorkerThreads* pretouch_workers, double* expand_time_ms) {
1213 size_t aligned_expand_bytes = ReservedSpace::page_align_size_up(expand_bytes);
1214 aligned_expand_bytes = align_up(aligned_expand_bytes,
1215 HeapRegion::GrainBytes);
1216
1217 log_debug(gc, ergo, heap)("Expand the heap. requested expansion amount: " SIZE_FORMAT "B expansion amount: " SIZE_FORMAT "B",
1218 expand_bytes, aligned_expand_bytes);
1219
1220 if (is_maximal_no_gc()) {
1221 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1222 return false;
1223 }
1224
1225 double expand_heap_start_time_sec = os::elapsedTime();
1226 uint regions_to_expand = (uint)(aligned_expand_bytes / HeapRegion::GrainBytes);
1227 assert(regions_to_expand > 0, "Must expand by at least one region");
1228
1229 uint expanded_by = _hrm.expand_by(regions_to_expand, pretouch_workers);
1230 if (expand_time_ms != NULL) {
1231 *expand_time_ms = (os::elapsedTime() - expand_heap_start_time_sec) * MILLIUNITS;
1232 }
1233
1234 if (expanded_by > 0) {
1235 size_t actual_expand_bytes = expanded_by * HeapRegion::GrainBytes;
1236 assert(actual_expand_bytes <= aligned_expand_bytes, "post-condition");
1237 policy()->record_new_heap_size(num_regions());
1238 } else {
1239 log_debug(gc, ergo, heap)("Did not expand the heap (heap expansion operation failed)");
1240
1241 // The expansion of the virtual storage space was unsuccessful.
1242 // Let's see if it was because we ran out of swap.
1243 if (G1ExitOnExpansionFailure &&
1244 _hrm.available() >= regions_to_expand) {
1245 // We had head room...
1246 vm_exit_out_of_memory(aligned_expand_bytes, OOM_MMAP_ERROR, "G1 heap expansion");
1247 }
1248 }
1249 return expanded_by > 0;
1250 }
1251
1252 bool G1CollectedHeap::expand_single_region(uint node_index) {
1253 uint expanded_by = _hrm.expand_on_preferred_node(node_index);
1254
1255 if (expanded_by == 0) {
1256 assert(is_maximal_no_gc(), "Should be no regions left, available: %u", _hrm.available());
1257 log_debug(gc, ergo, heap)("Did not expand the heap (heap already fully expanded)");
1258 return false;
1259 }
1260
1261 policy()->record_new_heap_size(num_regions());
1262 return true;
1263 }
1264
1265 void G1CollectedHeap::shrink_helper(size_t shrink_bytes) {
1266 size_t aligned_shrink_bytes =
1267 ReservedSpace::page_align_size_down(shrink_bytes);
1268 aligned_shrink_bytes = align_down(aligned_shrink_bytes,
1269 HeapRegion::GrainBytes);
1270 uint num_regions_to_remove = (uint)(shrink_bytes / HeapRegion::GrainBytes);
1271
1272 uint num_regions_removed = _hrm.shrink_by(num_regions_to_remove);
1273 size_t shrunk_bytes = num_regions_removed * HeapRegion::GrainBytes;
1274
1275 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",
1276 shrink_bytes, aligned_shrink_bytes, shrunk_bytes);
1277 if (num_regions_removed > 0) {
1278 log_debug(gc, heap)("Uncommittable regions after shrink: %u", num_regions_removed);
1279 policy()->record_new_heap_size(num_regions());
1280 } else {
1281 log_debug(gc, ergo, heap)("Did not shrink the heap (heap shrinking operation failed)");
1282 }
1283 }
1284
1285 void G1CollectedHeap::shrink(size_t shrink_bytes) {
1286 _verifier->verify_region_sets_optional();
1287
1288 // We should only reach here at the end of a Full GC or during Remark which
1289 // means we should not not be holding to any GC alloc regions. The method
1290 // below will make sure of that and do any remaining clean up.
1291 _allocator->abandon_gc_alloc_regions();
1292
1293 // Instead of tearing down / rebuilding the free lists here, we
1294 // could instead use the remove_all_pending() method on free_list to
1295 // remove only the ones that we need to remove.
1296 _hrm.remove_all_free_regions();
1297 shrink_helper(shrink_bytes);
1298 rebuild_region_sets(true /* free_list_only */);
1299
1300 _hrm.verify_optional();
1301 _verifier->verify_region_sets_optional();
1302 }
1303
1304 class OldRegionSetChecker : public HeapRegionSetChecker {
1305 public:
1306 void check_mt_safety() {
1307 // Master Old Set MT safety protocol:
1308 // (a) If we're at a safepoint, operations on the master old set
1309 // should be invoked:
1310 // - by the VM thread (which will serialize them), or
1311 // - by the GC workers while holding the FreeList_lock, if we're
1312 // at a safepoint for an evacuation pause (this lock is taken
1313 // anyway when an GC alloc region is retired so that a new one
1314 // is allocated from the free list), or
1315 // - by the GC workers while holding the OldSets_lock, if we're at a
1316 // safepoint for a cleanup pause.
1317 // (b) If we're not at a safepoint, operations on the master old set
1318 // should be invoked while holding the Heap_lock.
1319
1320 if (SafepointSynchronize::is_at_safepoint()) {
1321 guarantee(Thread::current()->is_VM_thread() ||
1322 FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
1323 "master old set MT safety protocol at a safepoint");
1324 } else {
1325 guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
1326 }
1327 }
1328 bool is_correct_type(HeapRegion* hr) { return hr->is_old(); }
1329 const char* get_description() { return "Old Regions"; }
1330 };
1331
1332 class ArchiveRegionSetChecker : public HeapRegionSetChecker {
1333 public:
1334 void check_mt_safety() {
1335 guarantee(!Universe::is_fully_initialized() || SafepointSynchronize::is_at_safepoint(),
1336 "May only change archive regions during initialization or safepoint.");
1337 }
1338 bool is_correct_type(HeapRegion* hr) { return hr->is_archive(); }
1339 const char* get_description() { return "Archive Regions"; }
1340 };
1341
1342 class HumongousRegionSetChecker : public HeapRegionSetChecker {
1343 public:
1344 void check_mt_safety() {
1345 // Humongous Set MT safety protocol:
1346 // (a) If we're at a safepoint, operations on the master humongous
1347 // set should be invoked by either the VM thread (which will
1348 // serialize them) or by the GC workers while holding the
1349 // OldSets_lock.
1350 // (b) If we're not at a safepoint, operations on the master
1351 // humongous set should be invoked while holding the Heap_lock.
1352
1353 if (SafepointSynchronize::is_at_safepoint()) {
1354 guarantee(Thread::current()->is_VM_thread() ||
1355 OldSets_lock->owned_by_self(),
1356 "master humongous set MT safety protocol at a safepoint");
1357 } else {
1358 guarantee(Heap_lock->owned_by_self(),
1359 "master humongous set MT safety protocol outside a safepoint");
1360 }
1361 }
1362 bool is_correct_type(HeapRegion* hr) { return hr->is_humongous(); }
1363 const char* get_description() { return "Humongous Regions"; }
1364 };
1365
1366 G1CollectedHeap::G1CollectedHeap() :
1367 CollectedHeap(),
1368 _service_thread(NULL),
1369 _periodic_gc_task(NULL),
1370 _free_arena_memory_task(NULL),
1371 _workers(NULL),
1372 _card_table(NULL),
1373 _collection_pause_end(Ticks::now()),
1374 _soft_ref_policy(),
1375 _old_set("Old Region Set", new OldRegionSetChecker()),
1376 _archive_set("Archive Region Set", new ArchiveRegionSetChecker()),
1377 _humongous_set("Humongous Region Set", new HumongousRegionSetChecker()),
1378 _bot(NULL),
1379 _listener(),
1380 _numa(G1NUMA::create()),
1381 _hrm(),
1382 _allocator(NULL),
1383 _evac_failure_injector(),
1384 _verifier(NULL),
1385 _summary_bytes_used(0),
1386 _bytes_used_during_gc(0),
1387 _survivor_evac_stats("Young", YoungPLABSize, PLABWeight),
1388 _old_evac_stats("Old", OldPLABSize, PLABWeight),
1389 _monitoring_support(nullptr),
1390 _num_humongous_objects(0),
1391 _num_humongous_reclaim_candidates(0),
1392 _hr_printer(),
1393 _collector_state(),
1394 _old_marking_cycles_started(0),
1395 _old_marking_cycles_completed(0),
1396 _eden(),
1397 _survivor(),
1398 _gc_timer_stw(new STWGCTimer()),
1399 _gc_tracer_stw(new G1NewTracer()),
1400 _policy(new G1Policy(_gc_timer_stw)),
1401 _heap_sizing_policy(NULL),
1402 _collection_set(this, _policy),
1403 _rem_set(NULL),
1404 _card_set_config(),
1405 _card_set_freelist_pool(G1CardSetConfiguration::num_mem_object_types()),
1406 _cm(NULL),
1407 _cm_thread(NULL),
1408 _cr(NULL),
1409 _task_queues(NULL),
1410 _ref_processor_stw(NULL),
1411 _is_alive_closure_stw(this),
1412 _is_subject_to_discovery_stw(this),
1413 _ref_processor_cm(NULL),
1414 _is_alive_closure_cm(this),
1415 _is_subject_to_discovery_cm(this),
1416 _region_attr() {
1417
1418 _verifier = new G1HeapVerifier(this);
1419
1420 _allocator = new G1Allocator(this);
1421
1422 _heap_sizing_policy = G1HeapSizingPolicy::create(this, _policy->analytics());
1423
1424 _humongous_object_threshold_in_words = humongous_threshold_for(HeapRegion::GrainWords);
1425
1426 // Override the default _filler_array_max_size so that no humongous filler
1427 // objects are created.
1428 _filler_array_max_size = _humongous_object_threshold_in_words;
1429
1430 // Override the default _stack_chunk_max_size so that no humongous stack chunks are created
1431 _stack_chunk_max_size = _humongous_object_threshold_in_words;
1432
1433 uint n_queues = ParallelGCThreads;
1434 _task_queues = new G1ScannerTasksQueueSet(n_queues);
1435
1436 for (uint i = 0; i < n_queues; i++) {
1437 G1ScannerTasksQueue* q = new G1ScannerTasksQueue();
1438 _task_queues->register_queue(i, q);
1439 }
1440
1441 _gc_tracer_stw->initialize();
1442
1443 guarantee(_task_queues != NULL, "task_queues allocation failure.");
1444 }
1445
1446 G1RegionToSpaceMapper* G1CollectedHeap::create_aux_memory_mapper(const char* description,
1447 size_t size,
1448 size_t translation_factor) {
1449 size_t preferred_page_size = os::page_size_for_region_unaligned(size, 1);
1450 // Allocate a new reserved space, preferring to use large pages.
1451 ReservedSpace rs(size, preferred_page_size);
1452 size_t page_size = rs.page_size();
1453 G1RegionToSpaceMapper* result =
1454 G1RegionToSpaceMapper::create_mapper(rs,
1455 size,
1456 page_size,
1457 HeapRegion::GrainBytes,
1458 translation_factor,
1459 mtGC);
1460
1461 os::trace_page_sizes_for_requested_size(description,
1462 size,
1463 page_size,
1464 preferred_page_size,
1465 rs.base(),
1466 rs.size());
1467
1468 return result;
1469 }
1470
1471 jint G1CollectedHeap::initialize_concurrent_refinement() {
1472 jint ecode = JNI_OK;
1473 _cr = G1ConcurrentRefine::create(policy(), &ecode);
1474 return ecode;
1475 }
1476
1477 jint G1CollectedHeap::initialize_service_thread() {
1478 _service_thread = new G1ServiceThread();
1479 if (_service_thread->osthread() == NULL) {
1480 vm_shutdown_during_initialization("Could not create G1ServiceThread");
1481 return JNI_ENOMEM;
1482 }
1483 return JNI_OK;
1484 }
1485
1486 jint G1CollectedHeap::initialize() {
1487
1488 // Necessary to satisfy locking discipline assertions.
1489
1490 MutexLocker x(Heap_lock);
1491
1492 // While there are no constraints in the GC code that HeapWordSize
1493 // be any particular value, there are multiple other areas in the
1494 // system which believe this to be true (e.g. oop->object_size in some
1495 // cases incorrectly returns the size in wordSize units rather than
1496 // HeapWordSize).
1497 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
1498
1499 size_t init_byte_size = InitialHeapSize;
1500 size_t reserved_byte_size = G1Arguments::heap_reserved_size_bytes();
1501
1502 // Ensure that the sizes are properly aligned.
1503 Universe::check_alignment(init_byte_size, HeapRegion::GrainBytes, "g1 heap");
1504 Universe::check_alignment(reserved_byte_size, HeapRegion::GrainBytes, "g1 heap");
1505 Universe::check_alignment(reserved_byte_size, HeapAlignment, "g1 heap");
1506
1507 // Reserve the maximum.
1508
1509 // When compressed oops are enabled, the preferred heap base
1510 // is calculated by subtracting the requested size from the
1511 // 32Gb boundary and using the result as the base address for
1512 // heap reservation. If the requested size is not aligned to
1513 // HeapRegion::GrainBytes (i.e. the alignment that is passed
1514 // into the ReservedHeapSpace constructor) then the actual
1515 // base of the reserved heap may end up differing from the
1516 // address that was requested (i.e. the preferred heap base).
1517 // If this happens then we could end up using a non-optimal
1518 // compressed oops mode.
1519
1520 ReservedHeapSpace heap_rs = Universe::reserve_heap(reserved_byte_size,
1521 HeapAlignment);
1522
1523 initialize_reserved_region(heap_rs);
1524
1525 _forwarding = new SlidingForwarding(heap_rs.region(), HeapRegion::LogOfHRGrainBytes - LogHeapWordSize);
1526
1527 // Create the barrier set for the entire reserved region.
1528 G1CardTable* ct = new G1CardTable(heap_rs.region());
1529 ct->initialize();
1530 G1BarrierSet* bs = new G1BarrierSet(ct);
1531 bs->initialize();
1532 assert(bs->is_a(BarrierSet::G1BarrierSet), "sanity");
1533 BarrierSet::set_barrier_set(bs);
1534 _card_table = ct;
1535
1536 {
1537 G1SATBMarkQueueSet& satbqs = bs->satb_mark_queue_set();
1538 satbqs.set_process_completed_buffers_threshold(G1SATBProcessCompletedThreshold);
1539 satbqs.set_buffer_enqueue_threshold_percentage(G1SATBBufferEnqueueingThresholdPercent);
1540 }
1541
1542 // Create space mappers.
1543 size_t page_size = heap_rs.page_size();
1544 G1RegionToSpaceMapper* heap_storage =
1545 G1RegionToSpaceMapper::create_mapper(heap_rs,
1546 heap_rs.size(),
1547 page_size,
1548 HeapRegion::GrainBytes,
1549 1,
1550 mtJavaHeap);
1551 if(heap_storage == NULL) {
1552 vm_shutdown_during_initialization("Could not initialize G1 heap");
1553 return JNI_ERR;
1554 }
1555
1556 os::trace_page_sizes("Heap",
1557 MinHeapSize,
1558 reserved_byte_size,
1559 page_size,
1560 heap_rs.base(),
1561 heap_rs.size());
1562 heap_storage->set_mapping_changed_listener(&_listener);
1563
1564 // Create storage for the BOT, card table and the bitmap.
1565 G1RegionToSpaceMapper* bot_storage =
1566 create_aux_memory_mapper("Block Offset Table",
1567 G1BlockOffsetTable::compute_size(heap_rs.size() / HeapWordSize),
1568 G1BlockOffsetTable::heap_map_factor());
1569
1570 G1RegionToSpaceMapper* cardtable_storage =
1571 create_aux_memory_mapper("Card Table",
1572 G1CardTable::compute_size(heap_rs.size() / HeapWordSize),
1573 G1CardTable::heap_map_factor());
1574
1575 size_t bitmap_size = G1CMBitMap::compute_size(heap_rs.size());
1576 G1RegionToSpaceMapper* bitmap_storage =
1577 create_aux_memory_mapper("Mark Bitmap", bitmap_size, G1CMBitMap::heap_map_factor());
1578
1579 _hrm.initialize(heap_storage, bitmap_storage, bot_storage, cardtable_storage);
1580 _card_table->initialize(cardtable_storage);
1581
1582 // 6843694 - ensure that the maximum region index can fit
1583 // in the remembered set structures.
1584 const uint max_region_idx = (1U << (sizeof(RegionIdx_t)*BitsPerByte-1)) - 1;
1585 guarantee((max_reserved_regions() - 1) <= max_region_idx, "too many regions");
1586
1587 // The G1FromCardCache reserves card with value 0 as "invalid", so the heap must not
1588 // start within the first card.
1589 guarantee((uintptr_t)(heap_rs.base()) >= G1CardTable::card_size(), "Java heap must not start within the first card.");
1590 G1FromCardCache::initialize(max_reserved_regions());
1591 // Also create a G1 rem set.
1592 _rem_set = new G1RemSet(this, _card_table);
1593 _rem_set->initialize(max_reserved_regions());
1594
1595 size_t max_cards_per_region = ((size_t)1 << (sizeof(CardIdx_t)*BitsPerByte-1)) - 1;
1596 guarantee(HeapRegion::CardsPerRegion > 0, "make sure it's initialized");
1597 guarantee(HeapRegion::CardsPerRegion < max_cards_per_region,
1598 "too many cards per region");
1599
1600 HeapRegionRemSet::initialize(_reserved);
1601
1602 FreeRegionList::set_unrealistically_long_length(max_regions() + 1);
1603
1604 _bot = new G1BlockOffsetTable(reserved(), bot_storage);
1605
1606 {
1607 size_t granularity = HeapRegion::GrainBytes;
1608
1609 _region_attr.initialize(reserved(), granularity);
1610 }
1611
1612 _workers = new WorkerThreads("GC Thread", ParallelGCThreads);
1613 if (_workers == NULL) {
1614 return JNI_ENOMEM;
1615 }
1616 _workers->initialize_workers();
1617
1618 _numa->set_region_info(HeapRegion::GrainBytes, page_size);
1619
1620 // Create the G1ConcurrentMark data structure and thread.
1621 // (Must do this late, so that "max_[reserved_]regions" is defined.)
1622 _cm = new G1ConcurrentMark(this, bitmap_storage);
1623 _cm_thread = _cm->cm_thread();
1624
1625 // Now expand into the initial heap size.
1626 if (!expand(init_byte_size, _workers)) {
1627 vm_shutdown_during_initialization("Failed to allocate initial heap.");
1628 return JNI_ENOMEM;
1629 }
1630
1631 // Perform any initialization actions delegated to the policy.
1632 policy()->init(this, &_collection_set);
1633
1634 jint ecode = initialize_concurrent_refinement();
1635 if (ecode != JNI_OK) {
1636 return ecode;
1637 }
1638
1639 ecode = initialize_service_thread();
1640 if (ecode != JNI_OK) {
1641 return ecode;
1642 }
1643
1644 // Create and schedule the periodic gc task on the service thread.
1645 _periodic_gc_task = new G1PeriodicGCTask("Periodic GC Task");
1646 _service_thread->register_task(_periodic_gc_task);
1647
1648 _free_arena_memory_task = new G1MonotonicArenaFreeMemoryTask("Card Set Free Memory Task");
1649 _service_thread->register_task(_free_arena_memory_task);
1650
1651 // Here we allocate the dummy HeapRegion that is required by the
1652 // G1AllocRegion class.
1653 HeapRegion* dummy_region = _hrm.get_dummy_region();
1654
1655 // We'll re-use the same region whether the alloc region will
1656 // require BOT updates or not and, if it doesn't, then a non-young
1657 // region will complain that it cannot support allocations without
1658 // BOT updates. So we'll tag the dummy region as eden to avoid that.
1659 dummy_region->set_eden();
1660 // Make sure it's full.
1661 dummy_region->set_top(dummy_region->end());
1662 G1AllocRegion::setup(this, dummy_region);
1663
1664 _allocator->init_mutator_alloc_regions();
1665
1666 // Do create of the monitoring and management support so that
1667 // values in the heap have been properly initialized.
1668 _monitoring_support = new G1MonitoringSupport(this);
1669
1670 _collection_set.initialize(max_reserved_regions());
1671
1672 evac_failure_injector()->reset();
1673
1674 G1InitLogger::print();
1675
1676 return JNI_OK;
1677 }
1678
1679 bool G1CollectedHeap::concurrent_mark_is_terminating() const {
1680 return _cm_thread->should_terminate();
1681 }
1682
1683 void G1CollectedHeap::stop() {
1684 // Stop all concurrent threads. We do this to make sure these threads
1685 // do not continue to execute and access resources (e.g. logging)
1686 // that are destroyed during shutdown.
1687 _cr->stop();
1688 _service_thread->stop();
1689 _cm_thread->stop();
1690 }
1691
1692 void G1CollectedHeap::safepoint_synchronize_begin() {
1693 SuspendibleThreadSet::synchronize();
1694 }
1695
1696 void G1CollectedHeap::safepoint_synchronize_end() {
1697 SuspendibleThreadSet::desynchronize();
1698 }
1699
1700 void G1CollectedHeap::post_initialize() {
1701 CollectedHeap::post_initialize();
1702 ref_processing_init();
1703 }
1704
1705 void G1CollectedHeap::ref_processing_init() {
1706 // Reference processing in G1 currently works as follows:
1707 //
1708 // * There are two reference processor instances. One is
1709 // used to record and process discovered references
1710 // during concurrent marking; the other is used to
1711 // record and process references during STW pauses
1712 // (both full and incremental).
1713 // * Both ref processors need to 'span' the entire heap as
1714 // the regions in the collection set may be dotted around.
1715 //
1716 // * For the concurrent marking ref processor:
1717 // * Reference discovery is enabled at concurrent start.
1718 // * Reference discovery is disabled and the discovered
1719 // references processed etc during remarking.
1720 // * Reference discovery is MT (see below).
1721 // * Reference discovery requires a barrier (see below).
1722 // * Reference processing may or may not be MT
1723 // (depending on the value of ParallelRefProcEnabled
1724 // and ParallelGCThreads).
1725 // * A full GC disables reference discovery by the CM
1726 // ref processor and abandons any entries on it's
1727 // discovered lists.
1728 //
1729 // * For the STW processor:
1730 // * Non MT discovery is enabled at the start of a full GC.
1731 // * Processing and enqueueing during a full GC is non-MT.
1732 // * During a full GC, references are processed after marking.
1733 //
1734 // * Discovery (may or may not be MT) is enabled at the start
1735 // of an incremental evacuation pause.
1736 // * References are processed near the end of a STW evacuation pause.
1737 // * For both types of GC:
1738 // * Discovery is atomic - i.e. not concurrent.
1739 // * Reference discovery will not need a barrier.
1740
1741 // Concurrent Mark ref processor
1742 _ref_processor_cm =
1743 new ReferenceProcessor(&_is_subject_to_discovery_cm,
1744 ParallelGCThreads, // degree of mt processing
1745 // We discover with the gc worker threads during Remark, so both
1746 // thread counts must be considered for discovery.
1747 MAX2(ParallelGCThreads, ConcGCThreads), // degree of mt discovery
1748 true, // Reference discovery is concurrent
1749 &_is_alive_closure_cm); // is alive closure
1750
1751 // STW ref processor
1752 _ref_processor_stw =
1753 new ReferenceProcessor(&_is_subject_to_discovery_stw,
1754 ParallelGCThreads, // degree of mt processing
1755 ParallelGCThreads, // degree of mt discovery
1756 false, // Reference discovery is not concurrent
1757 &_is_alive_closure_stw); // is alive closure
1758 }
1759
1760 SoftRefPolicy* G1CollectedHeap::soft_ref_policy() {
1761 return &_soft_ref_policy;
1762 }
1763
1764 size_t G1CollectedHeap::capacity() const {
1765 return _hrm.length() * HeapRegion::GrainBytes;
1766 }
1767
1768 size_t G1CollectedHeap::unused_committed_regions_in_bytes() const {
1769 return _hrm.total_free_bytes();
1770 }
1771
1772 // Computes the sum of the storage used by the various regions.
1773 size_t G1CollectedHeap::used() const {
1774 size_t result = _summary_bytes_used + _allocator->used_in_alloc_regions();
1775 return result;
1776 }
1777
1778 size_t G1CollectedHeap::used_unlocked() const {
1779 return _summary_bytes_used;
1780 }
1781
1782 class SumUsedClosure: public HeapRegionClosure {
1783 size_t _used;
1784 public:
1785 SumUsedClosure() : _used(0) {}
1786 bool do_heap_region(HeapRegion* r) {
1787 _used += r->used();
1788 return false;
1789 }
1790 size_t result() { return _used; }
1791 };
1792
1793 size_t G1CollectedHeap::recalculate_used() const {
1794 SumUsedClosure blk;
1795 heap_region_iterate(&blk);
1796 return blk.result();
1797 }
1798
1799 bool G1CollectedHeap::is_user_requested_concurrent_full_gc(GCCause::Cause cause) {
1800 return GCCause::is_user_requested_gc(cause) && ExplicitGCInvokesConcurrent;
1801 }
1802
1803 bool G1CollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
1804 switch (cause) {
1805 case GCCause::_g1_humongous_allocation: return true;
1806 case GCCause::_g1_periodic_collection: return G1PeriodicGCInvokesConcurrent;
1807 case GCCause::_wb_breakpoint: return true;
1808 case GCCause::_codecache_GC_aggressive: return true;
1809 case GCCause::_codecache_GC_threshold: return true;
1810 default: return is_user_requested_concurrent_full_gc(cause);
1811 }
1812 }
1813
1814 void G1CollectedHeap::increment_old_marking_cycles_started() {
1815 assert(_old_marking_cycles_started == _old_marking_cycles_completed ||
1816 _old_marking_cycles_started == _old_marking_cycles_completed + 1,
1817 "Wrong marking cycle count (started: %d, completed: %d)",
1818 _old_marking_cycles_started, _old_marking_cycles_completed);
1819
1820 _old_marking_cycles_started++;
1821 }
1822
1823 void G1CollectedHeap::increment_old_marking_cycles_completed(bool concurrent,
1824 bool whole_heap_examined) {
1825 MonitorLocker ml(G1OldGCCount_lock, Mutex::_no_safepoint_check_flag);
1826
1827 // We assume that if concurrent == true, then the caller is a
1828 // concurrent thread that was joined the Suspendible Thread
1829 // Set. If there's ever a cheap way to check this, we should add an
1830 // assert here.
1831
1832 // Given that this method is called at the end of a Full GC or of a
1833 // concurrent cycle, and those can be nested (i.e., a Full GC can
1834 // interrupt a concurrent cycle), the number of full collections
1835 // completed should be either one (in the case where there was no
1836 // nesting) or two (when a Full GC interrupted a concurrent cycle)
1837 // behind the number of full collections started.
1838
1839 // This is the case for the inner caller, i.e. a Full GC.
1840 assert(concurrent ||
1841 (_old_marking_cycles_started == _old_marking_cycles_completed + 1) ||
1842 (_old_marking_cycles_started == _old_marking_cycles_completed + 2),
1843 "for inner caller (Full GC): _old_marking_cycles_started = %u "
1844 "is inconsistent with _old_marking_cycles_completed = %u",
1845 _old_marking_cycles_started, _old_marking_cycles_completed);
1846
1847 // This is the case for the outer caller, i.e. the concurrent cycle.
1848 assert(!concurrent ||
1849 (_old_marking_cycles_started == _old_marking_cycles_completed + 1),
1850 "for outer caller (concurrent cycle): "
1851 "_old_marking_cycles_started = %u "
1852 "is inconsistent with _old_marking_cycles_completed = %u",
1853 _old_marking_cycles_started, _old_marking_cycles_completed);
1854
1855 _old_marking_cycles_completed += 1;
1856 if (whole_heap_examined) {
1857 // Signal that we have completed a visit to all live objects.
1858 record_whole_heap_examined_timestamp();
1859 }
1860
1861 // We need to clear the "in_progress" flag in the CM thread before
1862 // we wake up any waiters (especially when ExplicitInvokesConcurrent
1863 // is set) so that if a waiter requests another System.gc() it doesn't
1864 // incorrectly see that a marking cycle is still in progress.
1865 if (concurrent) {
1866 _cm_thread->set_idle();
1867 }
1868
1869 // Notify threads waiting in System.gc() (with ExplicitGCInvokesConcurrent)
1870 // for a full GC to finish that their wait is over.
1871 ml.notify_all();
1872 }
1873
1874 // Helper for collect().
1875 static G1GCCounters collection_counters(G1CollectedHeap* g1h) {
1876 MutexLocker ml(Heap_lock);
1877 return G1GCCounters(g1h);
1878 }
1879
1880 void G1CollectedHeap::collect(GCCause::Cause cause) {
1881 try_collect(cause, collection_counters(this));
1882 }
1883
1884 // Return true if (x < y) with allowance for wraparound.
1885 static bool gc_counter_less_than(uint x, uint y) {
1886 return (x - y) > (UINT_MAX/2);
1887 }
1888
1889 // LOG_COLLECT_CONCURRENTLY(cause, msg, args...)
1890 // Macro so msg printing is format-checked.
1891 #define LOG_COLLECT_CONCURRENTLY(cause, ...) \
1892 do { \
1893 LogTarget(Trace, gc) LOG_COLLECT_CONCURRENTLY_lt; \
1894 if (LOG_COLLECT_CONCURRENTLY_lt.is_enabled()) { \
1895 ResourceMark rm; /* For thread name. */ \
1896 LogStream LOG_COLLECT_CONCURRENTLY_s(&LOG_COLLECT_CONCURRENTLY_lt); \
1897 LOG_COLLECT_CONCURRENTLY_s.print("%s: Try Collect Concurrently (%s): ", \
1898 Thread::current()->name(), \
1899 GCCause::to_string(cause)); \
1900 LOG_COLLECT_CONCURRENTLY_s.print(__VA_ARGS__); \
1901 } \
1902 } while (0)
1903
1904 #define LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, result) \
1905 LOG_COLLECT_CONCURRENTLY(cause, "complete %s", BOOL_TO_STR(result))
1906
1907 bool G1CollectedHeap::try_collect_concurrently(GCCause::Cause cause,
1908 uint gc_counter,
1909 uint old_marking_started_before) {
1910 assert_heap_not_locked();
1911 assert(should_do_concurrent_full_gc(cause),
1912 "Non-concurrent cause %s", GCCause::to_string(cause));
1913
1914 for (uint i = 1; true; ++i) {
1915 // Try to schedule concurrent start evacuation pause that will
1916 // start a concurrent cycle.
1917 LOG_COLLECT_CONCURRENTLY(cause, "attempt %u", i);
1918 VM_G1TryInitiateConcMark op(gc_counter, cause);
1919 VMThread::execute(&op);
1920
1921 // Request is trivially finished.
1922 if (cause == GCCause::_g1_periodic_collection) {
1923 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, op.gc_succeeded());
1924 return op.gc_succeeded();
1925 }
1926
1927 // If VMOp skipped initiating concurrent marking cycle because
1928 // we're terminating, then we're done.
1929 if (op.terminating()) {
1930 LOG_COLLECT_CONCURRENTLY(cause, "skipped: terminating");
1931 return false;
1932 }
1933
1934 // Lock to get consistent set of values.
1935 uint old_marking_started_after;
1936 uint old_marking_completed_after;
1937 {
1938 MutexLocker ml(Heap_lock);
1939 // Update gc_counter for retrying VMOp if needed. Captured here to be
1940 // consistent with the values we use below for termination tests. If
1941 // a retry is needed after a possible wait, and another collection
1942 // occurs in the meantime, it will cause our retry to be skipped and
1943 // we'll recheck for termination with updated conditions from that
1944 // more recent collection. That's what we want, rather than having
1945 // our retry possibly perform an unnecessary collection.
1946 gc_counter = total_collections();
1947 old_marking_started_after = _old_marking_cycles_started;
1948 old_marking_completed_after = _old_marking_cycles_completed;
1949 }
1950
1951 if (cause == GCCause::_wb_breakpoint) {
1952 if (op.gc_succeeded()) {
1953 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1954 return true;
1955 }
1956 // When _wb_breakpoint there can't be another cycle or deferred.
1957 assert(!op.cycle_already_in_progress(), "invariant");
1958 assert(!op.whitebox_attached(), "invariant");
1959 // Concurrent cycle attempt might have been cancelled by some other
1960 // collection, so retry. Unlike other cases below, we want to retry
1961 // even if cancelled by a STW full collection, because we really want
1962 // to start a concurrent cycle.
1963 if (old_marking_started_before != old_marking_started_after) {
1964 LOG_COLLECT_CONCURRENTLY(cause, "ignoring STW full GC");
1965 old_marking_started_before = old_marking_started_after;
1966 }
1967 } else if (!GCCause::is_user_requested_gc(cause)) {
1968 // For an "automatic" (not user-requested) collection, we just need to
1969 // ensure that progress is made.
1970 //
1971 // Request is finished if any of
1972 // (1) the VMOp successfully performed a GC,
1973 // (2) a concurrent cycle was already in progress,
1974 // (3) whitebox is controlling concurrent cycles,
1975 // (4) a new cycle was started (by this thread or some other), or
1976 // (5) a Full GC was performed.
1977 // Cases (4) and (5) are detected together by a change to
1978 // _old_marking_cycles_started.
1979 //
1980 // Note that (1) does not imply (4). If we're still in the mixed
1981 // phase of an earlier concurrent collection, the request to make the
1982 // collection a concurrent start won't be honored. If we don't check for
1983 // both conditions we'll spin doing back-to-back collections.
1984 if (op.gc_succeeded() ||
1985 op.cycle_already_in_progress() ||
1986 op.whitebox_attached() ||
1987 (old_marking_started_before != old_marking_started_after)) {
1988 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
1989 return true;
1990 }
1991 } else { // User-requested GC.
1992 // For a user-requested collection, we want to ensure that a complete
1993 // full collection has been performed before returning, but without
1994 // waiting for more than needed.
1995
1996 // For user-requested GCs (unlike non-UR), a successful VMOp implies a
1997 // new cycle was started. That's good, because it's not clear what we
1998 // should do otherwise. Trying again just does back to back GCs.
1999 // Can't wait for someone else to start a cycle. And returning fails
2000 // to meet the goal of ensuring a full collection was performed.
2001 assert(!op.gc_succeeded() ||
2002 (old_marking_started_before != old_marking_started_after),
2003 "invariant: succeeded %s, started before %u, started after %u",
2004 BOOL_TO_STR(op.gc_succeeded()),
2005 old_marking_started_before, old_marking_started_after);
2006
2007 // Request is finished if a full collection (concurrent or stw)
2008 // was started after this request and has completed, e.g.
2009 // started_before < completed_after.
2010 if (gc_counter_less_than(old_marking_started_before,
2011 old_marking_completed_after)) {
2012 LOG_COLLECT_CONCURRENTLY_COMPLETE(cause, true);
2013 return true;
2014 }
2015
2016 if (old_marking_started_after != old_marking_completed_after) {
2017 // If there is an in-progress cycle (possibly started by us), then
2018 // wait for that cycle to complete, e.g.
2019 // while completed_now < started_after.
2020 LOG_COLLECT_CONCURRENTLY(cause, "wait");
2021 MonitorLocker ml(G1OldGCCount_lock);
2022 while (gc_counter_less_than(_old_marking_cycles_completed,
2023 old_marking_started_after)) {
2024 ml.wait();
2025 }
2026 // Request is finished if the collection we just waited for was
2027 // started after this request.
2028 if (old_marking_started_before != old_marking_started_after) {
2029 LOG_COLLECT_CONCURRENTLY(cause, "complete after wait");
2030 return true;
2031 }
2032 }
2033
2034 // If VMOp was successful then it started a new cycle that the above
2035 // wait &etc should have recognized as finishing this request. This
2036 // differs from a non-user-request, where gc_succeeded does not imply
2037 // a new cycle was started.
2038 assert(!op.gc_succeeded(), "invariant");
2039
2040 if (op.cycle_already_in_progress()) {
2041 // If VMOp failed because a cycle was already in progress, it
2042 // is now complete. But it didn't finish this user-requested
2043 // GC, so try again.
2044 LOG_COLLECT_CONCURRENTLY(cause, "retry after in-progress");
2045 continue;
2046 } else if (op.whitebox_attached()) {
2047 // If WhiteBox wants control, wait for notification of a state
2048 // change in the controller, then try again. Don't wait for
2049 // release of control, since collections may complete while in
2050 // control. Note: This won't recognize a STW full collection
2051 // while waiting; we can't wait on multiple monitors.
2052 LOG_COLLECT_CONCURRENTLY(cause, "whitebox control stall");
2053 MonitorLocker ml(ConcurrentGCBreakpoints::monitor());
2054 if (ConcurrentGCBreakpoints::is_controlled()) {
2055 ml.wait();
2056 }
2057 continue;
2058 }
2059 }
2060
2061 // Collection failed and should be retried.
2062 assert(op.transient_failure(), "invariant");
2063
2064 if (GCLocker::is_active_and_needs_gc()) {
2065 // If GCLocker is active, wait until clear before retrying.
2066 LOG_COLLECT_CONCURRENTLY(cause, "gc-locker stall");
2067 GCLocker::stall_until_clear();
2068 }
2069
2070 LOG_COLLECT_CONCURRENTLY(cause, "retry");
2071 }
2072 }
2073
2074 bool G1CollectedHeap::try_collect(GCCause::Cause cause,
2075 const G1GCCounters& counters_before) {
2076 if (should_do_concurrent_full_gc(cause)) {
2077 return try_collect_concurrently(cause,
2078 counters_before.total_collections(),
2079 counters_before.old_marking_cycles_started());
2080 } else if (GCLocker::should_discard(cause, counters_before.total_collections())) {
2081 // Indicate failure to be consistent with VMOp failure due to
2082 // another collection slipping in after our gc_count but before
2083 // our request is processed.
2084 return false;
2085 } else if (cause == GCCause::_gc_locker || cause == GCCause::_wb_young_gc
2086 DEBUG_ONLY(|| cause == GCCause::_scavenge_alot)) {
2087
2088 // Schedule a standard evacuation pause. We're setting word_size
2089 // to 0 which means that we are not requesting a post-GC allocation.
2090 VM_G1CollectForAllocation op(0, /* word_size */
2091 counters_before.total_collections(),
2092 cause);
2093 VMThread::execute(&op);
2094 return op.gc_succeeded();
2095 } else {
2096 // Schedule a Full GC.
2097 VM_G1CollectFull op(counters_before.total_collections(),
2098 counters_before.total_full_collections(),
2099 cause);
2100 VMThread::execute(&op);
2101 return op.gc_succeeded();
2102 }
2103 }
2104
2105 void G1CollectedHeap::start_concurrent_gc_for_metadata_allocation(GCCause::Cause gc_cause) {
2106 GCCauseSetter x(this, gc_cause);
2107
2108 // At this point we are supposed to start a concurrent cycle. We
2109 // will do so if one is not already in progress.
2110 bool should_start = policy()->force_concurrent_start_if_outside_cycle(gc_cause);
2111 if (should_start) {
2112 do_collection_pause_at_safepoint();
2113 }
2114 }
2115
2116 bool G1CollectedHeap::is_in(const void* p) const {
2117 return is_in_reserved(p) && _hrm.is_available(addr_to_region(p));
2118 }
2119
2120 // Iteration functions.
2121
2122 // Iterates an ObjectClosure over all objects within a HeapRegion.
2123
2124 class IterateObjectClosureRegionClosure: public HeapRegionClosure {
2125 ObjectClosure* _cl;
2126 public:
2127 IterateObjectClosureRegionClosure(ObjectClosure* cl) : _cl(cl) {}
2128 bool do_heap_region(HeapRegion* r) {
2129 if (!r->is_continues_humongous()) {
2130 r->object_iterate(_cl);
2131 }
2132 return false;
2133 }
2134 };
2135
2136 void G1CollectedHeap::object_iterate(ObjectClosure* cl) {
2137 IterateObjectClosureRegionClosure blk(cl);
2138 heap_region_iterate(&blk);
2139 }
2140
2141 class G1ParallelObjectIterator : public ParallelObjectIteratorImpl {
2142 private:
2143 G1CollectedHeap* _heap;
2144 HeapRegionClaimer _claimer;
2145
2146 public:
2147 G1ParallelObjectIterator(uint thread_num) :
2148 _heap(G1CollectedHeap::heap()),
2149 _claimer(thread_num == 0 ? G1CollectedHeap::heap()->workers()->active_workers() : thread_num) {}
2150
2151 virtual void object_iterate(ObjectClosure* cl, uint worker_id) {
2152 _heap->object_iterate_parallel(cl, worker_id, &_claimer);
2153 }
2154 };
2155
2156 ParallelObjectIteratorImpl* G1CollectedHeap::parallel_object_iterator(uint thread_num) {
2157 return new G1ParallelObjectIterator(thread_num);
2158 }
2159
2160 void G1CollectedHeap::object_iterate_parallel(ObjectClosure* cl, uint worker_id, HeapRegionClaimer* claimer) {
2161 IterateObjectClosureRegionClosure blk(cl);
2162 heap_region_par_iterate_from_worker_offset(&blk, claimer, worker_id);
2163 }
2164
2165 void G1CollectedHeap::keep_alive(oop obj) {
2166 G1BarrierSet::enqueue_preloaded(obj);
2167 }
2168
2169 void G1CollectedHeap::heap_region_iterate(HeapRegionClosure* cl) const {
2170 _hrm.iterate(cl);
2171 }
2172
2173 void G1CollectedHeap::heap_region_iterate(HeapRegionIndexClosure* cl) const {
2174 _hrm.iterate(cl);
2175 }
2176
2177 void G1CollectedHeap::heap_region_par_iterate_from_worker_offset(HeapRegionClosure* cl,
2178 HeapRegionClaimer *hrclaimer,
2179 uint worker_id) const {
2180 _hrm.par_iterate(cl, hrclaimer, hrclaimer->offset_for_worker(worker_id));
2181 }
2182
2183 void G1CollectedHeap::heap_region_par_iterate_from_start(HeapRegionClosure* cl,
2184 HeapRegionClaimer *hrclaimer) const {
2185 _hrm.par_iterate(cl, hrclaimer, 0);
2186 }
2187
2188 void G1CollectedHeap::collection_set_iterate_all(HeapRegionClosure* cl) {
2189 _collection_set.iterate(cl);
2190 }
2191
2192 void G1CollectedHeap::collection_set_par_iterate_all(HeapRegionClosure* cl,
2193 HeapRegionClaimer* hr_claimer,
2194 uint worker_id) {
2195 _collection_set.par_iterate(cl, hr_claimer, worker_id);
2196 }
2197
2198 void G1CollectedHeap::collection_set_iterate_increment_from(HeapRegionClosure *cl,
2199 HeapRegionClaimer* hr_claimer,
2200 uint worker_id) {
2201 _collection_set.iterate_incremental_part_from(cl, hr_claimer, worker_id);
2202 }
2203
2204 void G1CollectedHeap::par_iterate_regions_array(HeapRegionClosure* cl,
2205 HeapRegionClaimer* hr_claimer,
2206 const uint regions[],
2207 size_t length,
2208 uint worker_id) const {
2209 assert_at_safepoint();
2210 if (length == 0) {
2211 return;
2212 }
2213 uint total_workers = workers()->active_workers();
2214
2215 size_t start_pos = (worker_id * length) / total_workers;
2216 size_t cur_pos = start_pos;
2217
2218 do {
2219 uint region_idx = regions[cur_pos];
2220 if (hr_claimer == NULL || hr_claimer->claim_region(region_idx)) {
2221 HeapRegion* r = region_at(region_idx);
2222 bool result = cl->do_heap_region(r);
2223 guarantee(!result, "Must not cancel iteration");
2224 }
2225
2226 cur_pos++;
2227 if (cur_pos == length) {
2228 cur_pos = 0;
2229 }
2230 } while (cur_pos != start_pos);
2231 }
2232
2233 HeapWord* G1CollectedHeap::block_start(const void* addr) const {
2234 HeapRegion* hr = heap_region_containing(addr);
2235 // The CollectedHeap API requires us to not fail for any given address within
2236 // the heap. HeapRegion::block_start() has been optimized to not accept addresses
2237 // outside of the allocated area.
2238 if (addr >= hr->top()) {
2239 return nullptr;
2240 }
2241 return hr->block_start(addr);
2242 }
2243
2244 bool G1CollectedHeap::block_is_obj(const HeapWord* addr) const {
2245 HeapRegion* hr = heap_region_containing(addr);
2246 return hr->block_is_obj(addr, hr->parsable_bottom_acquire());
2247 }
2248
2249 size_t G1CollectedHeap::tlab_capacity(Thread* ignored) const {
2250 return (_policy->young_list_target_length() - _survivor.length()) * HeapRegion::GrainBytes;
2251 }
2252
2253 size_t G1CollectedHeap::tlab_used(Thread* ignored) const {
2254 return _eden.length() * HeapRegion::GrainBytes;
2255 }
2256
2257 // For G1 TLABs should not contain humongous objects, so the maximum TLAB size
2258 // must be equal to the humongous object limit.
2259 size_t G1CollectedHeap::max_tlab_size() const {
2260 return align_down(_humongous_object_threshold_in_words, MinObjAlignment);
2261 }
2262
2263 size_t G1CollectedHeap::unsafe_max_tlab_alloc(Thread* ignored) const {
2264 return _allocator->unsafe_max_tlab_alloc();
2265 }
2266
2267 size_t G1CollectedHeap::max_capacity() const {
2268 return max_regions() * HeapRegion::GrainBytes;
2269 }
2270
2271 void G1CollectedHeap::prepare_for_verify() {
2272 _verifier->prepare_for_verify();
2273 }
2274
2275 void G1CollectedHeap::verify(VerifyOption vo) {
2276 _verifier->verify(vo);
2277 }
2278
2279 bool G1CollectedHeap::supports_concurrent_gc_breakpoints() const {
2280 return true;
2281 }
2282
2283 bool G1CollectedHeap::is_archived_object(oop object) const {
2284 return object != NULL && heap_region_containing(object)->is_archive();
2285 }
2286
2287 class PrintRegionClosure: public HeapRegionClosure {
2288 outputStream* _st;
2289 public:
2290 PrintRegionClosure(outputStream* st) : _st(st) {}
2291 bool do_heap_region(HeapRegion* r) {
2292 r->print_on(_st);
2293 return false;
2294 }
2295 };
2296
2297 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2298 const HeapRegion* hr,
2299 const VerifyOption vo) const {
2300 switch (vo) {
2301 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj, hr);
2302 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj, hr);
2303 default: ShouldNotReachHere();
2304 }
2305 return false; // keep some compilers happy
2306 }
2307
2308 bool G1CollectedHeap::is_obj_dead_cond(const oop obj,
2309 const VerifyOption vo) const {
2310 switch (vo) {
2311 case VerifyOption::G1UseConcMarking: return is_obj_dead(obj);
2312 case VerifyOption::G1UseFullMarking: return is_obj_dead_full(obj);
2313 default: ShouldNotReachHere();
2314 }
2315 return false; // keep some compilers happy
2316 }
2317
2318 void G1CollectedHeap::pin_object(JavaThread* thread, oop obj) {
2319 GCLocker::lock_critical(thread);
2320 }
2321
2322 void G1CollectedHeap::unpin_object(JavaThread* thread, oop obj) {
2323 GCLocker::unlock_critical(thread);
2324 }
2325
2326 void G1CollectedHeap::print_heap_regions() const {
2327 LogTarget(Trace, gc, heap, region) lt;
2328 if (lt.is_enabled()) {
2329 LogStream ls(lt);
2330 print_regions_on(&ls);
2331 }
2332 }
2333
2334 void G1CollectedHeap::print_on(outputStream* st) const {
2335 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2336 st->print(" %-20s", "garbage-first heap");
2337 st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
2338 capacity()/K, heap_used/K);
2339 st->print(" [" PTR_FORMAT ", " PTR_FORMAT ")",
2340 p2i(_hrm.reserved().start()),
2341 p2i(_hrm.reserved().end()));
2342 st->cr();
2343 st->print(" region size " SIZE_FORMAT "K, ", HeapRegion::GrainBytes / K);
2344 uint young_regions = young_regions_count();
2345 st->print("%u young (" SIZE_FORMAT "K), ", young_regions,
2346 (size_t) young_regions * HeapRegion::GrainBytes / K);
2347 uint survivor_regions = survivor_regions_count();
2348 st->print("%u survivors (" SIZE_FORMAT "K)", survivor_regions,
2349 (size_t) survivor_regions * HeapRegion::GrainBytes / K);
2350 st->cr();
2351 if (_numa->is_enabled()) {
2352 uint num_nodes = _numa->num_active_nodes();
2353 st->print(" remaining free region(s) on each NUMA node: ");
2354 const int* node_ids = _numa->node_ids();
2355 for (uint node_index = 0; node_index < num_nodes; node_index++) {
2356 uint num_free_regions = _hrm.num_free_regions(node_index);
2357 st->print("%d=%u ", node_ids[node_index], num_free_regions);
2358 }
2359 st->cr();
2360 }
2361 MetaspaceUtils::print_on(st);
2362 }
2363
2364 void G1CollectedHeap::print_regions_on(outputStream* st) const {
2365 st->print_cr("Heap Regions: E=young(eden), S=young(survivor), O=old, "
2366 "HS=humongous(starts), HC=humongous(continues), "
2367 "CS=collection set, F=free, "
2368 "OA=open archive, CA=closed archive, "
2369 "TAMS=top-at-mark-start, "
2370 "PB=parsable bottom");
2371 PrintRegionClosure blk(st);
2372 heap_region_iterate(&blk);
2373 }
2374
2375 void G1CollectedHeap::print_extended_on(outputStream* st) const {
2376 print_on(st);
2377
2378 // Print the per-region information.
2379 st->cr();
2380 print_regions_on(st);
2381 }
2382
2383 void G1CollectedHeap::print_on_error(outputStream* st) const {
2384 this->CollectedHeap::print_on_error(st);
2385
2386 if (_cm != NULL) {
2387 st->cr();
2388 _cm->print_on_error(st);
2389 }
2390 }
2391
2392 void G1CollectedHeap::gc_threads_do(ThreadClosure* tc) const {
2393 workers()->threads_do(tc);
2394 tc->do_thread(_cm_thread);
2395 _cm->threads_do(tc);
2396 _cr->threads_do(tc);
2397 tc->do_thread(_service_thread);
2398 }
2399
2400 void G1CollectedHeap::print_tracing_info() const {
2401 rem_set()->print_summary_info();
2402 concurrent_mark()->print_summary_info();
2403 }
2404
2405 bool G1CollectedHeap::print_location(outputStream* st, void* addr) const {
2406 return BlockLocationPrinter<G1CollectedHeap>::print_location(st, addr);
2407 }
2408
2409 G1HeapSummary G1CollectedHeap::create_g1_heap_summary() {
2410
2411 size_t eden_used_bytes = _monitoring_support->eden_space_used();
2412 size_t survivor_used_bytes = _monitoring_support->survivor_space_used();
2413 size_t old_gen_used_bytes = _monitoring_support->old_gen_used();
2414 size_t heap_used = Heap_lock->owned_by_self() ? used() : used_unlocked();
2415
2416 size_t eden_capacity_bytes =
2417 (policy()->young_list_target_length() * HeapRegion::GrainBytes) - survivor_used_bytes;
2418
2419 VirtualSpaceSummary heap_summary = create_heap_space_summary();
2420 return G1HeapSummary(heap_summary, heap_used, eden_used_bytes, eden_capacity_bytes,
2421 survivor_used_bytes, old_gen_used_bytes, num_regions());
2422 }
2423
2424 G1EvacSummary G1CollectedHeap::create_g1_evac_summary(G1EvacStats* stats) {
2425 return G1EvacSummary(stats->allocated(), stats->wasted(), stats->undo_wasted(),
2426 stats->unused(), stats->used(), stats->region_end_waste(),
2427 stats->regions_filled(), stats->num_plab_filled(),
2428 stats->direct_allocated(), stats->num_direct_allocated(),
2429 stats->failure_used(), stats->failure_waste());
2430 }
2431
2432 void G1CollectedHeap::trace_heap(GCWhen::Type when, const GCTracer* gc_tracer) {
2433 const G1HeapSummary& heap_summary = create_g1_heap_summary();
2434 gc_tracer->report_gc_heap_summary(when, heap_summary);
2435
2436 const MetaspaceSummary& metaspace_summary = create_metaspace_summary();
2437 gc_tracer->report_metaspace_summary(when, metaspace_summary);
2438 }
2439
2440 void G1CollectedHeap::gc_prologue(bool full) {
2441 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
2442
2443 // Update common counters.
2444 increment_total_collections(full /* full gc */);
2445 if (full || collector_state()->in_concurrent_start_gc()) {
2446 increment_old_marking_cycles_started();
2447 }
2448 }
2449
2450 void G1CollectedHeap::gc_epilogue(bool full) {
2451 // Update common counters.
2452 if (full) {
2453 // Update the number of full collections that have been completed.
2454 increment_old_marking_cycles_completed(false /* concurrent */, true /* liveness_completed */);
2455 }
2456
2457 #if COMPILER2_OR_JVMCI
2458 assert(DerivedPointerTable::is_empty(), "derived pointer present");
2459 #endif
2460
2461 // We have just completed a GC. Update the soft reference
2462 // policy with the new heap occupancy
2463 Universe::heap()->update_capacity_and_used_at_gc();
2464
2465 _collection_pause_end = Ticks::now();
2466
2467 _free_arena_memory_task->notify_new_stats(&_young_gen_card_set_stats,
2468 &_collection_set_candidates_card_set_stats);
2469 }
2470
2471 uint G1CollectedHeap::uncommit_regions(uint region_limit) {
2472 return _hrm.uncommit_inactive_regions(region_limit);
2473 }
2474
2475 bool G1CollectedHeap::has_uncommittable_regions() {
2476 return _hrm.has_inactive_regions();
2477 }
2478
2479 void G1CollectedHeap::uncommit_regions_if_necessary() {
2480 if (has_uncommittable_regions()) {
2481 G1UncommitRegionTask::enqueue();
2482 }
2483 }
2484
2485 void G1CollectedHeap::verify_numa_regions(const char* desc) {
2486 LogTarget(Trace, gc, heap, verify) lt;
2487
2488 if (lt.is_enabled()) {
2489 LogStream ls(lt);
2490 // Iterate all heap regions to print matching between preferred numa id and actual numa id.
2491 G1NodeIndexCheckClosure cl(desc, _numa, &ls);
2492 heap_region_iterate(&cl);
2493 }
2494 }
2495
2496 HeapWord* G1CollectedHeap::do_collection_pause(size_t word_size,
2497 uint gc_count_before,
2498 bool* succeeded,
2499 GCCause::Cause gc_cause) {
2500 assert_heap_not_locked_and_not_at_safepoint();
2501 VM_G1CollectForAllocation op(word_size, gc_count_before, gc_cause);
2502 VMThread::execute(&op);
2503
2504 HeapWord* result = op.result();
2505 bool ret_succeeded = op.prologue_succeeded() && op.gc_succeeded();
2506 assert(result == NULL || ret_succeeded,
2507 "the result should be NULL if the VM did not succeed");
2508 *succeeded = ret_succeeded;
2509
2510 assert_heap_not_locked();
2511 return result;
2512 }
2513
2514 void G1CollectedHeap::start_concurrent_cycle(bool concurrent_operation_is_full_mark) {
2515 assert(!_cm_thread->in_progress(), "Can not start concurrent operation while in progress");
2516
2517 MutexLocker x(CGC_lock, Mutex::_no_safepoint_check_flag);
2518 if (concurrent_operation_is_full_mark) {
2519 _cm->post_concurrent_mark_start();
2520 _cm_thread->start_full_mark();
2521 } else {
2522 _cm->post_concurrent_undo_start();
2523 _cm_thread->start_undo_mark();
2524 }
2525 CGC_lock->notify();
2526 }
2527
2528 bool G1CollectedHeap::is_potential_eager_reclaim_candidate(HeapRegion* r) const {
2529 // We don't nominate objects with many remembered set entries, on
2530 // the assumption that such objects are likely still live.
2531 HeapRegionRemSet* rem_set = r->rem_set();
2532
2533 return rem_set->occupancy_less_or_equal_than(G1EagerReclaimRemSetThreshold);
2534 }
2535
2536 #ifndef PRODUCT
2537 void G1CollectedHeap::verify_region_attr_remset_is_tracked() {
2538 class VerifyRegionAttrRemSet : public HeapRegionClosure {
2539 public:
2540 virtual bool do_heap_region(HeapRegion* r) {
2541 G1CollectedHeap* g1h = G1CollectedHeap::heap();
2542 bool const remset_is_tracked = g1h->region_attr(r->bottom()).remset_is_tracked();
2543 assert(r->rem_set()->is_tracked() == remset_is_tracked,
2544 "Region %u remset tracking status (%s) different to region attribute (%s)",
2545 r->hrm_index(), BOOL_TO_STR(r->rem_set()->is_tracked()), BOOL_TO_STR(remset_is_tracked));
2546 return false;
2547 }
2548 } cl;
2549 heap_region_iterate(&cl);
2550 }
2551 #endif
2552
2553 void G1CollectedHeap::start_new_collection_set() {
2554 collection_set()->start_incremental_building();
2555
2556 clear_region_attr();
2557
2558 guarantee(_eden.length() == 0, "eden should have been cleared");
2559 policy()->transfer_survivors_to_cset(survivor());
2560
2561 // We redo the verification but now wrt to the new CSet which
2562 // has just got initialized after the previous CSet was freed.
2563 _cm->verify_no_collection_set_oops();
2564 }
2565
2566 G1HeapVerifier::G1VerifyType G1CollectedHeap::young_collection_verify_type() const {
2567 if (collector_state()->in_concurrent_start_gc()) {
2568 return G1HeapVerifier::G1VerifyConcurrentStart;
2569 } else if (collector_state()->in_young_only_phase()) {
2570 return G1HeapVerifier::G1VerifyYoungNormal;
2571 } else {
2572 return G1HeapVerifier::G1VerifyMixed;
2573 }
2574 }
2575
2576 void G1CollectedHeap::verify_before_young_collection(G1HeapVerifier::G1VerifyType type) {
2577 if (!VerifyBeforeGC) {
2578 return;
2579 }
2580 Ticks start = Ticks::now();
2581 _verifier->prepare_for_verify();
2582 _verifier->verify_region_sets_optional();
2583 _verifier->verify_dirty_young_regions();
2584 _verifier->verify_before_gc(type);
2585 verify_numa_regions("GC Start");
2586 phase_times()->record_verify_before_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2587 }
2588
2589 void G1CollectedHeap::verify_after_young_collection(G1HeapVerifier::G1VerifyType type) {
2590 if (!VerifyAfterGC) {
2591 return;
2592 }
2593 Ticks start = Ticks::now();
2594 _verifier->verify_after_gc(type);
2595 verify_numa_regions("GC End");
2596 _verifier->verify_region_sets_optional();
2597 phase_times()->record_verify_after_time_ms((Ticks::now() - start).seconds() * MILLIUNITS);
2598 }
2599
2600 void G1CollectedHeap::expand_heap_after_young_collection(){
2601 size_t expand_bytes = _heap_sizing_policy->young_collection_expansion_amount();
2602 if (expand_bytes > 0) {
2603 // No need for an ergo logging here,
2604 // expansion_amount() does this when it returns a value > 0.
2605 double expand_ms = 0.0;
2606 if (!expand(expand_bytes, _workers, &expand_ms)) {
2607 // We failed to expand the heap. Cannot do anything about it.
2608 }
2609 phase_times()->record_expand_heap_time(expand_ms);
2610 }
2611 }
2612
2613 bool G1CollectedHeap::do_collection_pause_at_safepoint() {
2614 assert_at_safepoint_on_vm_thread();
2615 guarantee(!is_gc_active(), "collection is not reentrant");
2616
2617 if (GCLocker::check_active_before_gc()) {
2618 return false;
2619 }
2620
2621 do_collection_pause_at_safepoint_helper();
2622 return true;
2623 }
2624
2625 G1HeapPrinterMark::G1HeapPrinterMark(G1CollectedHeap* g1h) : _g1h(g1h), _heap_transition(g1h) {
2626 // This summary needs to be printed before incrementing total collections.
2627 _g1h->rem_set()->print_periodic_summary_info("Before GC RS summary",
2628 _g1h->total_collections(),
2629 true /* show_thread_times */);
2630 _g1h->print_heap_before_gc();
2631 _g1h->print_heap_regions();
2632 }
2633
2634 G1HeapPrinterMark::~G1HeapPrinterMark() {
2635 _g1h->policy()->print_age_table();
2636 _g1h->rem_set()->print_coarsen_stats();
2637 // We are at the end of the GC. Total collections has already been increased.
2638 _g1h->rem_set()->print_periodic_summary_info("After GC RS summary",
2639 _g1h->total_collections() - 1,
2640 false /* show_thread_times */);
2641
2642 _heap_transition.print();
2643 _g1h->print_heap_regions();
2644 _g1h->print_heap_after_gc();
2645 // Print NUMA statistics.
2646 _g1h->numa()->print_statistics();
2647 }
2648
2649 G1JFRTracerMark::G1JFRTracerMark(STWGCTimer* timer, GCTracer* tracer) :
2650 _timer(timer), _tracer(tracer) {
2651
2652 _timer->register_gc_start();
2653 _tracer->report_gc_start(G1CollectedHeap::heap()->gc_cause(), _timer->gc_start());
2654 G1CollectedHeap::heap()->trace_heap_before_gc(_tracer);
2655 }
2656
2657 G1JFRTracerMark::~G1JFRTracerMark() {
2658 G1CollectedHeap::heap()->trace_heap_after_gc(_tracer);
2659 _timer->register_gc_end();
2660 _tracer->report_gc_end(_timer->gc_end(), _timer->time_partitions());
2661 }
2662
2663 void G1CollectedHeap::prepare_for_mutator_after_young_collection() {
2664 Ticks start = Ticks::now();
2665
2666 _survivor_evac_stats.adjust_desired_plab_size();
2667 _old_evac_stats.adjust_desired_plab_size();
2668
2669 // Start a new incremental collection set for the mutator phase.
2670 start_new_collection_set();
2671 _allocator->init_mutator_alloc_regions();
2672
2673 phase_times()->record_prepare_for_mutator_time_ms((Ticks::now() - start).seconds() * 1000.0);
2674 }
2675
2676 void G1CollectedHeap::retire_tlabs() {
2677 ensure_parsability(true);
2678 }
2679
2680 void G1CollectedHeap::do_collection_pause_at_safepoint_helper() {
2681 ResourceMark rm;
2682
2683 IsGCActiveMark active_gc_mark;
2684 GCIdMark gc_id_mark;
2685 SvcGCMarker sgcm(SvcGCMarker::MINOR);
2686
2687 GCTraceCPUTime tcpu(_gc_tracer_stw);
2688
2689 _bytes_used_during_gc = 0;
2690
2691 policy()->decide_on_concurrent_start_pause();
2692 // Record whether this pause may need to trigger a concurrent operation. Later,
2693 // when we signal the G1ConcurrentMarkThread, the collector state has already
2694 // been reset for the next pause.
2695 bool should_start_concurrent_mark_operation = collector_state()->in_concurrent_start_gc();
2696
2697 // Perform the collection.
2698 G1YoungCollector collector(gc_cause());
2699 collector.collect();
2700
2701 // It should now be safe to tell the concurrent mark thread to start
2702 // without its logging output interfering with the logging output
2703 // that came from the pause.
2704 if (should_start_concurrent_mark_operation) {
2705 verifier()->verify_bitmap_clear(true /* above_tams_only */);
2706 // CAUTION: after the start_concurrent_cycle() call below, the concurrent marking
2707 // thread(s) could be running concurrently with us. Make sure that anything
2708 // after this point does not assume that we are the only GC thread running.
2709 // Note: of course, the actual marking work will not start until the safepoint
2710 // itself is released in SuspendibleThreadSet::desynchronize().
2711 start_concurrent_cycle(collector.concurrent_operation_is_full_mark());
2712 ConcurrentGCBreakpoints::notify_idle_to_active();
2713 }
2714 }
2715
2716 void G1CollectedHeap::complete_cleaning(bool class_unloading_occurred) {
2717 uint num_workers = workers()->active_workers();
2718 G1ParallelCleaningTask unlink_task(num_workers, class_unloading_occurred);
2719 workers()->run_task(&unlink_task);
2720 }
2721
2722 bool G1STWSubjectToDiscoveryClosure::do_object_b(oop obj) {
2723 assert(obj != NULL, "must not be NULL");
2724 assert(_g1h->is_in_reserved(obj), "Trying to discover obj " PTR_FORMAT " not in heap", p2i(obj));
2725 // The areas the CM and STW ref processor manage must be disjoint. The is_in_cset() below
2726 // may falsely indicate that this is not the case here: however the collection set only
2727 // contains old regions when concurrent mark is not running.
2728 return _g1h->is_in_cset(obj) || _g1h->heap_region_containing(obj)->is_survivor();
2729 }
2730
2731 void G1CollectedHeap::make_pending_list_reachable() {
2732 if (collector_state()->in_concurrent_start_gc()) {
2733 oop pll_head = Universe::reference_pending_list();
2734 if (pll_head != NULL) {
2735 // Any valid worker id is fine here as we are in the VM thread and single-threaded.
2736 _cm->mark_in_bitmap(0 /* worker_id */, pll_head);
2737 }
2738 }
2739 }
2740
2741 void G1CollectedHeap::set_humongous_stats(uint num_humongous_total, uint num_humongous_candidates) {
2742 _num_humongous_objects = num_humongous_total;
2743 _num_humongous_reclaim_candidates = num_humongous_candidates;
2744 }
2745
2746 bool G1CollectedHeap::should_sample_collection_set_candidates() const {
2747 G1CollectionSetCandidates* candidates = G1CollectedHeap::heap()->collection_set()->candidates();
2748 return candidates != NULL && candidates->num_remaining() > 0;
2749 }
2750
2751 void G1CollectedHeap::set_collection_set_candidates_stats(G1MonotonicArenaMemoryStats& stats) {
2752 _collection_set_candidates_card_set_stats = stats;
2753 }
2754
2755 void G1CollectedHeap::set_young_gen_card_set_stats(const G1MonotonicArenaMemoryStats& stats) {
2756 _young_gen_card_set_stats = stats;
2757 }
2758
2759 void G1CollectedHeap::record_obj_copy_mem_stats() {
2760 policy()->old_gen_alloc_tracker()->
2761 add_allocated_bytes_since_last_gc(_old_evac_stats.allocated() * HeapWordSize);
2762
2763 _gc_tracer_stw->report_evacuation_statistics(create_g1_evac_summary(&_survivor_evac_stats),
2764 create_g1_evac_summary(&_old_evac_stats));
2765 }
2766
2767 void G1CollectedHeap::clear_bitmap_for_region(HeapRegion* hr) {
2768 concurrent_mark()->clear_bitmap_for_region(hr);
2769 }
2770
2771 void G1CollectedHeap::free_region(HeapRegion* hr, FreeRegionList* free_list) {
2772 assert(!hr->is_free(), "the region should not be free");
2773 assert(!hr->is_empty(), "the region should not be empty");
2774 assert(_hrm.is_available(hr->hrm_index()), "region should be committed");
2775
2776 // Reset region metadata to allow reuse.
2777 hr->hr_clear(true /* clear_space */);
2778 _policy->remset_tracker()->update_at_free(hr);
2779
2780 if (free_list != NULL) {
2781 free_list->add_ordered(hr);
2782 }
2783 }
2784
2785 void G1CollectedHeap::free_humongous_region(HeapRegion* hr,
2786 FreeRegionList* free_list) {
2787 assert(hr->is_humongous(), "this is only for humongous regions");
2788 hr->clear_humongous();
2789 free_region(hr, free_list);
2790 }
2791
2792 void G1CollectedHeap::remove_from_old_gen_sets(const uint old_regions_removed,
2793 const uint archive_regions_removed,
2794 const uint humongous_regions_removed) {
2795 if (old_regions_removed > 0 || archive_regions_removed > 0 || humongous_regions_removed > 0) {
2796 MutexLocker x(OldSets_lock, Mutex::_no_safepoint_check_flag);
2797 _old_set.bulk_remove(old_regions_removed);
2798 _archive_set.bulk_remove(archive_regions_removed);
2799 _humongous_set.bulk_remove(humongous_regions_removed);
2800 }
2801
2802 }
2803
2804 void G1CollectedHeap::prepend_to_freelist(FreeRegionList* list) {
2805 assert(list != NULL, "list can't be null");
2806 if (!list->is_empty()) {
2807 MutexLocker x(FreeList_lock, Mutex::_no_safepoint_check_flag);
2808 _hrm.insert_list_into_free_list(list);
2809 }
2810 }
2811
2812 void G1CollectedHeap::decrement_summary_bytes(size_t bytes) {
2813 decrease_used(bytes);
2814 }
2815
2816 void G1CollectedHeap::clear_eden() {
2817 _eden.clear();
2818 }
2819
2820 void G1CollectedHeap::clear_collection_set() {
2821 collection_set()->clear();
2822 }
2823
2824 void G1CollectedHeap::rebuild_free_region_list() {
2825 Ticks start = Ticks::now();
2826 _hrm.rebuild_free_list(workers());
2827 phase_times()->record_total_rebuild_freelist_time_ms((Ticks::now() - start).seconds() * 1000.0);
2828 }
2829
2830 class G1AbandonCollectionSetClosure : public HeapRegionClosure {
2831 public:
2832 virtual bool do_heap_region(HeapRegion* r) {
2833 assert(r->in_collection_set(), "Region %u must have been in collection set", r->hrm_index());
2834 G1CollectedHeap::heap()->clear_region_attr(r);
2835 r->clear_young_index_in_cset();
2836 return false;
2837 }
2838 };
2839
2840 void G1CollectedHeap::abandon_collection_set(G1CollectionSet* collection_set) {
2841 G1AbandonCollectionSetClosure cl;
2842 collection_set_iterate_all(&cl);
2843
2844 collection_set->clear();
2845 collection_set->stop_incremental_building();
2846 }
2847
2848 bool G1CollectedHeap::is_old_gc_alloc_region(HeapRegion* hr) {
2849 return _allocator->is_retained_old_region(hr);
2850 }
2851
2852 void G1CollectedHeap::set_region_short_lived_locked(HeapRegion* hr) {
2853 _eden.add(hr);
2854 _policy->set_region_eden(hr);
2855 }
2856
2857 #ifdef ASSERT
2858
2859 class NoYoungRegionsClosure: public HeapRegionClosure {
2860 private:
2861 bool _success;
2862 public:
2863 NoYoungRegionsClosure() : _success(true) { }
2864 bool do_heap_region(HeapRegion* r) {
2865 if (r->is_young()) {
2866 log_error(gc, verify)("Region [" PTR_FORMAT ", " PTR_FORMAT ") tagged as young",
2867 p2i(r->bottom()), p2i(r->end()));
2868 _success = false;
2869 }
2870 return false;
2871 }
2872 bool success() { return _success; }
2873 };
2874
2875 bool G1CollectedHeap::check_young_list_empty() {
2876 bool ret = (young_regions_count() == 0);
2877
2878 NoYoungRegionsClosure closure;
2879 heap_region_iterate(&closure);
2880 ret = ret && closure.success();
2881
2882 return ret;
2883 }
2884
2885 #endif // ASSERT
2886
2887 // Remove the given HeapRegion from the appropriate region set.
2888 void G1CollectedHeap::prepare_region_for_full_compaction(HeapRegion* hr) {
2889 if (hr->is_archive()) {
2890 _archive_set.remove(hr);
2891 } else if (hr->is_humongous()) {
2892 _humongous_set.remove(hr);
2893 } else if (hr->is_old()) {
2894 _old_set.remove(hr);
2895 } else if (hr->is_young()) {
2896 // Note that emptying the eden and survivor lists is postponed and instead
2897 // done as the first step when rebuilding the regions sets again. The reason
2898 // for this is that during a full GC string deduplication needs to know if
2899 // a collected region was young or old when the full GC was initiated.
2900 hr->uninstall_surv_rate_group();
2901 } else {
2902 // We ignore free regions, we'll empty the free list afterwards.
2903 assert(hr->is_free(), "it cannot be another type");
2904 }
2905 }
2906
2907 void G1CollectedHeap::increase_used(size_t bytes) {
2908 _summary_bytes_used += bytes;
2909 }
2910
2911 void G1CollectedHeap::decrease_used(size_t bytes) {
2912 assert(_summary_bytes_used >= bytes,
2913 "invariant: _summary_bytes_used: " SIZE_FORMAT " should be >= bytes: " SIZE_FORMAT,
2914 _summary_bytes_used, bytes);
2915 _summary_bytes_used -= bytes;
2916 }
2917
2918 void G1CollectedHeap::set_used(size_t bytes) {
2919 _summary_bytes_used = bytes;
2920 }
2921
2922 class RebuildRegionSetsClosure : public HeapRegionClosure {
2923 private:
2924 bool _free_list_only;
2925
2926 HeapRegionSet* _old_set;
2927 HeapRegionSet* _archive_set;
2928 HeapRegionSet* _humongous_set;
2929
2930 HeapRegionManager* _hrm;
2931
2932 size_t _total_used;
2933
2934 public:
2935 RebuildRegionSetsClosure(bool free_list_only,
2936 HeapRegionSet* old_set,
2937 HeapRegionSet* archive_set,
2938 HeapRegionSet* humongous_set,
2939 HeapRegionManager* hrm) :
2940 _free_list_only(free_list_only), _old_set(old_set), _archive_set(archive_set),
2941 _humongous_set(humongous_set), _hrm(hrm), _total_used(0) {
2942 assert(_hrm->num_free_regions() == 0, "pre-condition");
2943 if (!free_list_only) {
2944 assert(_old_set->is_empty(), "pre-condition");
2945 assert(_archive_set->is_empty(), "pre-condition");
2946 assert(_humongous_set->is_empty(), "pre-condition");
2947 }
2948 }
2949
2950 bool do_heap_region(HeapRegion* r) {
2951 if (r->is_empty()) {
2952 assert(r->rem_set()->is_empty(), "Empty regions should have empty remembered sets.");
2953 // Add free regions to the free list
2954 r->set_free();
2955 _hrm->insert_into_free_list(r);
2956 } else if (!_free_list_only) {
2957 assert(r->rem_set()->is_empty(), "At this point remembered sets must have been cleared.");
2958
2959 if (r->is_humongous()) {
2960 _humongous_set->add(r);
2961 } else if (r->is_archive()) {
2962 _archive_set->add(r);
2963 } else {
2964 assert(r->is_young() || r->is_free() || r->is_old(), "invariant");
2965 // We now move all (non-humongous, non-old, non-archive) regions to old gen,
2966 // and register them as such.
2967 r->move_to_old();
2968 _old_set->add(r);
2969 }
2970 _total_used += r->used();
2971 }
2972
2973 return false;
2974 }
2975
2976 size_t total_used() {
2977 return _total_used;
2978 }
2979 };
2980
2981 void G1CollectedHeap::rebuild_region_sets(bool free_list_only) {
2982 assert_at_safepoint_on_vm_thread();
2983
2984 if (!free_list_only) {
2985 _eden.clear();
2986 _survivor.clear();
2987 }
2988
2989 RebuildRegionSetsClosure cl(free_list_only,
2990 &_old_set, &_archive_set, &_humongous_set,
2991 &_hrm);
2992 heap_region_iterate(&cl);
2993
2994 if (!free_list_only) {
2995 set_used(cl.total_used());
2996 }
2997 assert_used_and_recalculate_used_equal(this);
2998 }
2999
3000 // Methods for the mutator alloc region
3001
3002 HeapRegion* G1CollectedHeap::new_mutator_alloc_region(size_t word_size,
3003 bool force,
3004 uint node_index) {
3005 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3006 bool should_allocate = policy()->should_allocate_mutator_region();
3007 if (force || should_allocate) {
3008 HeapRegion* new_alloc_region = new_region(word_size,
3009 HeapRegionType::Eden,
3010 false /* do_expand */,
3011 node_index);
3012 if (new_alloc_region != NULL) {
3013 set_region_short_lived_locked(new_alloc_region);
3014 _hr_printer.alloc(new_alloc_region, !should_allocate);
3015 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3016 return new_alloc_region;
3017 }
3018 }
3019 return NULL;
3020 }
3021
3022 void G1CollectedHeap::retire_mutator_alloc_region(HeapRegion* alloc_region,
3023 size_t allocated_bytes) {
3024 assert_heap_locked_or_at_safepoint(true /* should_be_vm_thread */);
3025 assert(alloc_region->is_eden(), "all mutator alloc regions should be eden");
3026
3027 collection_set()->add_eden_region(alloc_region);
3028 increase_used(allocated_bytes);
3029 _eden.add_used_bytes(allocated_bytes);
3030 _hr_printer.retire(alloc_region);
3031
3032 // We update the eden sizes here, when the region is retired,
3033 // instead of when it's allocated, since this is the point that its
3034 // used space has been recorded in _summary_bytes_used.
3035 monitoring_support()->update_eden_size();
3036 }
3037
3038 // Methods for the GC alloc regions
3039
3040 bool G1CollectedHeap::has_more_regions(G1HeapRegionAttr dest) {
3041 if (dest.is_old()) {
3042 return true;
3043 } else {
3044 return survivor_regions_count() < policy()->max_survivor_regions();
3045 }
3046 }
3047
3048 HeapRegion* G1CollectedHeap::new_gc_alloc_region(size_t word_size, G1HeapRegionAttr dest, uint node_index) {
3049 assert(FreeList_lock->owned_by_self(), "pre-condition");
3050
3051 if (!has_more_regions(dest)) {
3052 return NULL;
3053 }
3054
3055 HeapRegionType type;
3056 if (dest.is_young()) {
3057 type = HeapRegionType::Survivor;
3058 } else {
3059 type = HeapRegionType::Old;
3060 }
3061
3062 HeapRegion* new_alloc_region = new_region(word_size,
3063 type,
3064 true /* do_expand */,
3065 node_index);
3066
3067 if (new_alloc_region != NULL) {
3068 if (type.is_survivor()) {
3069 new_alloc_region->set_survivor();
3070 _survivor.add(new_alloc_region);
3071 register_new_survivor_region_with_region_attr(new_alloc_region);
3072 } else {
3073 new_alloc_region->set_old();
3074 }
3075 _policy->remset_tracker()->update_at_allocate(new_alloc_region);
3076 register_region_with_region_attr(new_alloc_region);
3077 _hr_printer.alloc(new_alloc_region);
3078 return new_alloc_region;
3079 }
3080 return NULL;
3081 }
3082
3083 void G1CollectedHeap::retire_gc_alloc_region(HeapRegion* alloc_region,
3084 size_t allocated_bytes,
3085 G1HeapRegionAttr dest) {
3086 _bytes_used_during_gc += allocated_bytes;
3087 if (dest.is_old()) {
3088 old_set_add(alloc_region);
3089 } else {
3090 assert(dest.is_young(), "Retiring alloc region should be young (%d)", dest.type());
3091 _survivor.add_used_bytes(allocated_bytes);
3092 }
3093
3094 bool const during_im = collector_state()->in_concurrent_start_gc();
3095 if (during_im && allocated_bytes > 0) {
3096 _cm->add_root_region(alloc_region);
3097 }
3098 _hr_printer.retire(alloc_region);
3099 }
3100
3101 HeapRegion* G1CollectedHeap::alloc_highest_free_region() {
3102 bool expanded = false;
3103 uint index = _hrm.find_highest_free(&expanded);
3104
3105 if (index != G1_NO_HRM_INDEX) {
3106 if (expanded) {
3107 log_debug(gc, ergo, heap)("Attempt heap expansion (requested address range outside heap bounds). region size: " SIZE_FORMAT "B",
3108 HeapRegion::GrainWords * HeapWordSize);
3109 }
3110 return _hrm.allocate_free_regions_starting_at(index, 1);
3111 }
3112 return NULL;
3113 }
3114
3115 void G1CollectedHeap::mark_evac_failure_object(uint worker_id, const oop obj, size_t obj_size) const {
3116 assert(!_cm->is_marked_in_bitmap(obj), "must be");
3117
3118 _cm->raw_mark_in_bitmap(obj);
3119 if (collector_state()->in_concurrent_start_gc()) {
3120 _cm->add_to_liveness(worker_id, obj, obj_size);
3121 }
3122 }
3123
3124 // Optimized nmethod scanning
3125 class RegisterNMethodOopClosure: public OopClosure {
3126 G1CollectedHeap* _g1h;
3127 nmethod* _nm;
3128
3129 public:
3130 RegisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3131 _g1h(g1h), _nm(nm) {}
3132
3133 void do_oop(oop* p) {
3134 oop heap_oop = RawAccess<>::oop_load(p);
3135 if (!CompressedOops::is_null(heap_oop)) {
3136 oop obj = CompressedOops::decode_not_null(heap_oop);
3137 HeapRegion* hr = _g1h->heap_region_containing(obj);
3138 assert(!hr->is_continues_humongous(),
3139 "trying to add code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3140 " starting at " HR_FORMAT,
3141 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3142
3143 // HeapRegion::add_code_root_locked() avoids adding duplicate entries.
3144 hr->add_code_root_locked(_nm);
3145 }
3146 }
3147
3148 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3149 };
3150
3151 class UnregisterNMethodOopClosure: public OopClosure {
3152 G1CollectedHeap* _g1h;
3153 nmethod* _nm;
3154
3155 public:
3156 UnregisterNMethodOopClosure(G1CollectedHeap* g1h, nmethod* nm) :
3157 _g1h(g1h), _nm(nm) {}
3158
3159 void do_oop(oop* p) {
3160 oop heap_oop = RawAccess<>::oop_load(p);
3161 if (!CompressedOops::is_null(heap_oop)) {
3162 oop obj = CompressedOops::decode_not_null(heap_oop);
3163 HeapRegion* hr = _g1h->heap_region_containing(obj);
3164 assert(!hr->is_continues_humongous(),
3165 "trying to remove code root " PTR_FORMAT " in continuation of humongous region " HR_FORMAT
3166 " starting at " HR_FORMAT,
3167 p2i(_nm), HR_FORMAT_PARAMS(hr), HR_FORMAT_PARAMS(hr->humongous_start_region()));
3168
3169 hr->remove_code_root(_nm);
3170 }
3171 }
3172
3173 void do_oop(narrowOop* p) { ShouldNotReachHere(); }
3174 };
3175
3176 void G1CollectedHeap::register_nmethod(nmethod* nm) {
3177 guarantee(nm != NULL, "sanity");
3178 RegisterNMethodOopClosure reg_cl(this, nm);
3179 nm->oops_do(®_cl);
3180 }
3181
3182 void G1CollectedHeap::unregister_nmethod(nmethod* nm) {
3183 guarantee(nm != NULL, "sanity");
3184 UnregisterNMethodOopClosure reg_cl(this, nm);
3185 nm->oops_do(®_cl, true);
3186 }
3187
3188 void G1CollectedHeap::update_used_after_gc(bool evacuation_failed) {
3189 if (evacuation_failed) {
3190 // Reset the G1EvacuationFailureALot counters and flags
3191 evac_failure_injector()->reset();
3192
3193 set_used(recalculate_used());
3194 } else {
3195 // The "used" of the collection set have already been subtracted
3196 // when they were freed. Add in the bytes used.
3197 increase_used(_bytes_used_during_gc);
3198 }
3199 }
3200
3201 class RebuildCodeRootClosure: public CodeBlobClosure {
3202 G1CollectedHeap* _g1h;
3203
3204 public:
3205 RebuildCodeRootClosure(G1CollectedHeap* g1h) :
3206 _g1h(g1h) {}
3207
3208 void do_code_blob(CodeBlob* cb) {
3209 nmethod* nm = cb->as_nmethod_or_null();
3210 if (nm != NULL) {
3211 _g1h->register_nmethod(nm);
3212 }
3213 }
3214 };
3215
3216 void G1CollectedHeap::rebuild_code_roots() {
3217 RebuildCodeRootClosure blob_cl(this);
3218 CodeCache::blobs_do(&blob_cl);
3219 }
3220
3221 void G1CollectedHeap::initialize_serviceability() {
3222 _monitoring_support->initialize_serviceability();
3223 }
3224
3225 MemoryUsage G1CollectedHeap::memory_usage() {
3226 return _monitoring_support->memory_usage();
3227 }
3228
3229 GrowableArray<GCMemoryManager*> G1CollectedHeap::memory_managers() {
3230 return _monitoring_support->memory_managers();
3231 }
3232
3233 GrowableArray<MemoryPool*> G1CollectedHeap::memory_pools() {
3234 return _monitoring_support->memory_pools();
3235 }
3236
3237 void G1CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap) {
3238 HeapRegion* region = heap_region_containing(start);
3239 region->fill_with_dummy_object(start, pointer_delta(end, start), zap);
3240 }
3241
3242 void G1CollectedHeap::start_codecache_marking_cycle_if_inactive(bool concurrent_mark_start) {
3243 // We can reach here with an active code cache marking cycle either because the
3244 // previous G1 concurrent marking cycle was undone (if heap occupancy after the
3245 // concurrent start young collection was below the threshold) or aborted. See
3246 // CodeCache::on_gc_marking_cycle_finish() why this is. We must not start a new code
3247 // cache cycle then. If we are about to start a new g1 concurrent marking cycle we
3248 // still have to arm all nmethod entry barriers. They are needed for adding oop
3249 // constants to the SATB snapshot. Full GC does not need nmethods to be armed.
3250 if (!CodeCache::is_gc_marking_cycle_active()) {
3251 CodeCache::on_gc_marking_cycle_start();
3252 }
3253 if (concurrent_mark_start) {
3254 CodeCache::arm_all_nmethods();
3255 }
3256 }
3257
3258 void G1CollectedHeap::finish_codecache_marking_cycle() {
3259 CodeCache::on_gc_marking_cycle_finish();
3260 CodeCache::arm_all_nmethods();
3261 }