1 /*
2 * Copyright (c) 2000, 2020, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "aot/aotLoader.hpp"
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/stringTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/icBuffer.hpp"
34 #include "gc/serial/defNewGeneration.hpp"
35 #include "gc/shared/adaptiveSizePolicy.hpp"
36 #include "gc/shared/cardTableBarrierSet.hpp"
37 #include "gc/shared/cardTableRS.hpp"
38 #include "gc/shared/collectedHeap.inline.hpp"
39 #include "gc/shared/collectorCounters.hpp"
40 #include "gc/shared/gcId.hpp"
41 #include "gc/shared/gcLocker.hpp"
42 #include "gc/shared/gcPolicyCounters.hpp"
43 #include "gc/shared/gcTrace.hpp"
44 #include "gc/shared/gcTraceTime.inline.hpp"
45 #include "gc/shared/genArguments.hpp"
46 #include "gc/shared/gcVMOperations.hpp"
47 #include "gc/shared/genCollectedHeap.hpp"
48 #include "gc/shared/genOopClosures.inline.hpp"
49 #include "gc/shared/generationSpec.hpp"
50 #include "gc/shared/locationPrinter.inline.hpp"
51 #include "gc/shared/oopStorageParState.inline.hpp"
52 #include "gc/shared/scavengableNMethods.hpp"
53 #include "gc/shared/space.hpp"
54 #include "gc/shared/strongRootsScope.hpp"
55 #include "gc/shared/weakProcessor.hpp"
56 #include "gc/shared/workgroup.hpp"
57 #include "memory/filemap.hpp"
58 #include "memory/iterator.hpp"
59 #include "memory/metaspaceCounters.hpp"
60 #include "memory/resourceArea.hpp"
61 #include "memory/universe.hpp"
62 #include "oops/oop.inline.hpp"
63 #include "runtime/biasedLocking.hpp"
64 #include "runtime/flags/flagSetting.hpp"
65 #include "runtime/handles.hpp"
66 #include "runtime/handles.inline.hpp"
67 #include "runtime/java.hpp"
68 #include "runtime/vmThread.hpp"
69 #include "services/management.hpp"
70 #include "services/memoryService.hpp"
71 #include "utilities/debug.hpp"
72 #include "utilities/formatBuffer.hpp"
73 #include "utilities/macros.hpp"
74 #include "utilities/stack.inline.hpp"
75 #include "utilities/vmError.hpp"
76 #if INCLUDE_JVMCI
77 #include "jvmci/jvmci.hpp"
78 #endif
79
80 GenCollectedHeap::GenCollectedHeap(Generation::Name young,
81 Generation::Name old,
82 const char* policy_counters_name) :
83 CollectedHeap(),
84 _young_gen_spec(new GenerationSpec(young,
85 NewSize,
86 MaxNewSize,
87 GenAlignment)),
88 _old_gen_spec(new GenerationSpec(old,
89 OldSize,
90 MaxOldSize,
91 GenAlignment)),
92 _rem_set(NULL),
93 _soft_ref_gen_policy(),
94 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
95 _full_collections_completed(0),
96 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)) {
97 }
98
99 jint GenCollectedHeap::initialize() {
100 // While there are no constraints in the GC code that HeapWordSize
101 // be any particular value, there are multiple other areas in the
102 // system which believe this to be true (e.g. oop->object_size in some
103 // cases incorrectly returns the size in wordSize units rather than
104 // HeapWordSize).
105 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
106
107 // Allocate space for the heap.
108
109 ReservedHeapSpace heap_rs = allocate(HeapAlignment);
110
111 if (!heap_rs.is_reserved()) {
112 vm_shutdown_during_initialization(
113 "Could not reserve enough space for object heap");
114 return JNI_ENOMEM;
115 }
116
117 initialize_reserved_region(heap_rs);
118
119 _rem_set = create_rem_set(heap_rs.region());
120 _rem_set->initialize();
121 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
122 bs->initialize();
123 BarrierSet::set_barrier_set(bs);
124
125 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false);
126 _young_gen = _young_gen_spec->init(young_rs, rem_set());
127 ReservedSpace old_rs = heap_rs.last_part(_young_gen_spec->max_size());
128
129 old_rs = old_rs.first_part(_old_gen_spec->max_size(), false, false);
130 _old_gen = _old_gen_spec->init(old_rs, rem_set());
131 clear_incremental_collection_failed();
132
133 return JNI_OK;
134 }
135
136 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
137 return new CardTableRS(reserved_region, false /* scan_concurrently */);
138 }
139
140 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
141 size_t init_promo_size,
142 size_t init_survivor_size) {
143 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
144 _size_policy = new AdaptiveSizePolicy(init_eden_size,
145 init_promo_size,
146 init_survivor_size,
147 max_gc_pause_sec,
148 GCTimeRatio);
149 }
150
151 ReservedHeapSpace GenCollectedHeap::allocate(size_t alignment) {
152 // Now figure out the total size.
153 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
154 assert(alignment % pageSize == 0, "Must be");
155
156 // Check for overflow.
157 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
158 if (total_reserved < _young_gen_spec->max_size()) {
159 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
160 "the maximum representable size");
161 }
162 assert(total_reserved % alignment == 0,
163 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
164 SIZE_FORMAT, total_reserved, alignment);
165
166 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment);
167
168 os::trace_page_sizes("Heap",
169 MinHeapSize,
170 total_reserved,
171 alignment,
172 heap_rs.base(),
173 heap_rs.size());
174
175 return heap_rs;
176 }
177
178 class GenIsScavengable : public BoolObjectClosure {
179 public:
180 bool do_object_b(oop obj) {
181 return GenCollectedHeap::heap()->is_in_young(obj);
182 }
183 };
184
185 static GenIsScavengable _is_scavengable;
186
187 void GenCollectedHeap::post_initialize() {
188 CollectedHeap::post_initialize();
189 ref_processing_init();
190
191 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
192
193 initialize_size_policy(def_new_gen->eden()->capacity(),
194 _old_gen->capacity(),
195 def_new_gen->from()->capacity());
196
197 MarkSweep::initialize();
198
199 ScavengableNMethods::initialize(&_is_scavengable);
200 }
201
202 void GenCollectedHeap::ref_processing_init() {
203 _young_gen->ref_processor_init();
204 _old_gen->ref_processor_init();
205 }
206
207 PreGenGCValues GenCollectedHeap::get_pre_gc_values() const {
208 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
209
210 return PreGenGCValues(def_new_gen->used(),
211 def_new_gen->capacity(),
212 def_new_gen->eden()->used(),
213 def_new_gen->eden()->capacity(),
214 def_new_gen->from()->used(),
215 def_new_gen->from()->capacity(),
216 old_gen()->used(),
217 old_gen()->capacity());
218 }
219
220 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
221 return _young_gen_spec;
222 }
223
224 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
225 return _old_gen_spec;
226 }
227
228 size_t GenCollectedHeap::capacity() const {
229 return _young_gen->capacity() + _old_gen->capacity();
230 }
231
232 size_t GenCollectedHeap::used() const {
233 return _young_gen->used() + _old_gen->used();
234 }
235
236 void GenCollectedHeap::save_used_regions() {
237 _old_gen->save_used_region();
238 _young_gen->save_used_region();
239 }
240
241 size_t GenCollectedHeap::max_capacity() const {
242 return _young_gen->max_capacity() + _old_gen->max_capacity();
243 }
244
245 // Update the _full_collections_completed counter
246 // at the end of a stop-world full GC.
247 unsigned int GenCollectedHeap::update_full_collections_completed() {
248 MonitorLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
249 assert(_full_collections_completed <= _total_full_collections,
250 "Can't complete more collections than were started");
251 _full_collections_completed = _total_full_collections;
252 ml.notify_all();
253 return _full_collections_completed;
254 }
255
256 // Update the _full_collections_completed counter, as appropriate,
257 // at the end of a concurrent GC cycle. Note the conditional update
258 // below to allow this method to be called by a concurrent collector
259 // without synchronizing in any manner with the VM thread (which
260 // may already have initiated a STW full collection "concurrently").
261 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
262 MonitorLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
263 assert((_full_collections_completed <= _total_full_collections) &&
264 (count <= _total_full_collections),
265 "Can't complete more collections than were started");
266 if (count > _full_collections_completed) {
267 _full_collections_completed = count;
268 ml.notify_all();
269 }
270 return _full_collections_completed;
271 }
272
273 // Return true if any of the following is true:
274 // . the allocation won't fit into the current young gen heap
275 // . gc locker is occupied (jni critical section)
276 // . heap memory is tight -- the most recent previous collection
277 // was a full collection because a partial collection (would
278 // have) failed and is likely to fail again
279 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
280 size_t young_capacity = _young_gen->capacity_before_gc();
281 return (word_size > heap_word_size(young_capacity))
282 || GCLocker::is_active_and_needs_gc()
283 || incremental_collection_failed();
284 }
285
286 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
287 HeapWord* result = NULL;
288 if (_old_gen->should_allocate(size, is_tlab)) {
289 result = _old_gen->expand_and_allocate(size, is_tlab);
290 }
291 if (result == NULL) {
292 if (_young_gen->should_allocate(size, is_tlab)) {
293 result = _young_gen->expand_and_allocate(size, is_tlab);
294 }
295 }
296 assert(result == NULL || is_in_reserved(result), "result not in heap");
297 return result;
298 }
299
300 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
301 bool is_tlab,
302 bool* gc_overhead_limit_was_exceeded) {
303 // In general gc_overhead_limit_was_exceeded should be false so
304 // set it so here and reset it to true only if the gc time
305 // limit is being exceeded as checked below.
306 *gc_overhead_limit_was_exceeded = false;
307
308 HeapWord* result = NULL;
309
310 // Loop until the allocation is satisfied, or unsatisfied after GC.
311 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
312 HandleMark hm; // Discard any handles allocated in each iteration.
313
314 // First allocation attempt is lock-free.
315 Generation *young = _young_gen;
316 assert(young->supports_inline_contig_alloc(),
317 "Otherwise, must do alloc within heap lock");
318 if (young->should_allocate(size, is_tlab)) {
319 result = young->par_allocate(size, is_tlab);
320 if (result != NULL) {
321 assert(is_in_reserved(result), "result not in heap");
322 return result;
323 }
324 }
325 uint gc_count_before; // Read inside the Heap_lock locked region.
326 {
327 MutexLocker ml(Heap_lock);
328 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
329 // Note that only large objects get a shot at being
330 // allocated in later generations.
331 bool first_only = !should_try_older_generation_allocation(size);
332
333 result = attempt_allocation(size, is_tlab, first_only);
334 if (result != NULL) {
335 assert(is_in_reserved(result), "result not in heap");
336 return result;
337 }
338
339 if (GCLocker::is_active_and_needs_gc()) {
340 if (is_tlab) {
341 return NULL; // Caller will retry allocating individual object.
342 }
343 if (!is_maximal_no_gc()) {
344 // Try and expand heap to satisfy request.
345 result = expand_heap_and_allocate(size, is_tlab);
346 // Result could be null if we are out of space.
347 if (result != NULL) {
348 return result;
349 }
350 }
351
352 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
353 return NULL; // We didn't get to do a GC and we didn't get any memory.
354 }
355
356 // If this thread is not in a jni critical section, we stall
357 // the requestor until the critical section has cleared and
358 // GC allowed. When the critical section clears, a GC is
359 // initiated by the last thread exiting the critical section; so
360 // we retry the allocation sequence from the beginning of the loop,
361 // rather than causing more, now probably unnecessary, GC attempts.
362 JavaThread* jthr = JavaThread::current();
363 if (!jthr->in_critical()) {
364 MutexUnlocker mul(Heap_lock);
365 // Wait for JNI critical section to be exited
366 GCLocker::stall_until_clear();
367 gclocker_stalled_count += 1;
368 continue;
369 } else {
370 if (CheckJNICalls) {
371 fatal("Possible deadlock due to allocating while"
372 " in jni critical section");
373 }
374 return NULL;
375 }
376 }
377
378 // Read the gc count while the heap lock is held.
379 gc_count_before = total_collections();
380 }
381
382 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
383 VMThread::execute(&op);
384 if (op.prologue_succeeded()) {
385 result = op.result();
386 if (op.gc_locked()) {
387 assert(result == NULL, "must be NULL if gc_locked() is true");
388 continue; // Retry and/or stall as necessary.
389 }
390
391 // Allocation has failed and a collection
392 // has been done. If the gc time limit was exceeded the
393 // this time, return NULL so that an out-of-memory
394 // will be thrown. Clear gc_overhead_limit_exceeded
395 // so that the overhead exceeded does not persist.
396
397 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
398 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
399
400 if (limit_exceeded && softrefs_clear) {
401 *gc_overhead_limit_was_exceeded = true;
402 size_policy()->set_gc_overhead_limit_exceeded(false);
403 if (op.result() != NULL) {
404 CollectedHeap::fill_with_object(op.result(), size);
405 }
406 return NULL;
407 }
408 assert(result == NULL || is_in_reserved(result),
409 "result not in heap");
410 return result;
411 }
412
413 // Give a warning if we seem to be looping forever.
414 if ((QueuedAllocationWarningCount > 0) &&
415 (try_count % QueuedAllocationWarningCount == 0)) {
416 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
417 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
418 }
419 }
420 }
421
422 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
423 bool is_tlab,
424 bool first_only) {
425 HeapWord* res = NULL;
426
427 if (_young_gen->should_allocate(size, is_tlab)) {
428 res = _young_gen->allocate(size, is_tlab);
429 if (res != NULL || first_only) {
430 return res;
431 }
432 }
433
434 if (_old_gen->should_allocate(size, is_tlab)) {
435 res = _old_gen->allocate(size, is_tlab);
436 }
437
438 return res;
439 }
440
441 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
442 bool* gc_overhead_limit_was_exceeded) {
443 return mem_allocate_work(size,
444 false /* is_tlab */,
445 gc_overhead_limit_was_exceeded);
446 }
447
448 bool GenCollectedHeap::must_clear_all_soft_refs() {
449 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
450 _gc_cause == GCCause::_wb_full_gc;
451 }
452
453 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
454 bool is_tlab, bool run_verification, bool clear_soft_refs,
455 bool restore_marks_for_biased_locking) {
456 FormatBuffer<> title("Collect gen: %s", gen->short_name());
457 GCTraceTime(Trace, gc, phases) t1(title);
458 TraceCollectorStats tcs(gen->counters());
459 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
460
461 gen->stat_record()->invocations++;
462 gen->stat_record()->accumulated_time.start();
463
464 // Must be done anew before each collection because
465 // a previous collection will do mangling and will
466 // change top of some spaces.
467 record_gen_tops_before_GC();
468
469 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
470
471 if (run_verification && VerifyBeforeGC) {
472 HandleMark hm; // Discard invalid handles created during verification
473 Universe::verify("Before GC");
474 }
475 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear());
476
477 if (restore_marks_for_biased_locking) {
478 // We perform this mark word preservation work lazily
479 // because it's only at this point that we know whether we
480 // absolutely have to do it; we want to avoid doing it for
481 // scavenge-only collections where it's unnecessary
482 BiasedLocking::preserve_marks();
483 }
484
485 // Do collection work
486 {
487 // Note on ref discovery: For what appear to be historical reasons,
488 // GCH enables and disabled (by enqueing) refs discovery.
489 // In the future this should be moved into the generation's
490 // collect method so that ref discovery and enqueueing concerns
491 // are local to a generation. The collect method could return
492 // an appropriate indication in the case that notification on
493 // the ref lock was needed. This will make the treatment of
494 // weak refs more uniform (and indeed remove such concerns
495 // from GCH). XXX
496
497 HandleMark hm; // Discard invalid handles created during gc
498 save_marks(); // save marks for all gens
499 // We want to discover references, but not process them yet.
500 // This mode is disabled in process_discovered_references if the
501 // generation does some collection work, or in
502 // enqueue_discovered_references if the generation returns
503 // without doing any work.
504 ReferenceProcessor* rp = gen->ref_processor();
505 // If the discovery of ("weak") refs in this generation is
506 // atomic wrt other collectors in this configuration, we
507 // are guaranteed to have empty discovered ref lists.
508 if (rp->discovery_is_atomic()) {
509 rp->enable_discovery();
510 rp->setup_policy(clear_soft_refs);
511 } else {
512 // collect() below will enable discovery as appropriate
513 }
514 gen->collect(full, clear_soft_refs, size, is_tlab);
515 if (!rp->enqueuing_is_done()) {
516 rp->disable_discovery();
517 } else {
518 rp->set_enqueuing_is_done(false);
519 }
520 rp->verify_no_references_recorded();
521 }
522
523 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers());
524
525 gen->stat_record()->accumulated_time.stop();
526
527 update_gc_stats(gen, full);
528
529 if (run_verification && VerifyAfterGC) {
530 HandleMark hm; // Discard invalid handles created during verification
531 Universe::verify("After GC");
532 }
533 }
534
535 void GenCollectedHeap::do_collection(bool full,
536 bool clear_all_soft_refs,
537 size_t size,
538 bool is_tlab,
539 GenerationType max_generation) {
540 ResourceMark rm;
541 DEBUG_ONLY(Thread* my_thread = Thread::current();)
542
543 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
544 assert(my_thread->is_VM_thread() ||
545 my_thread->is_ConcurrentGC_thread(),
546 "incorrect thread type capability");
547 assert(Heap_lock->is_locked(),
548 "the requesting thread should have the Heap_lock");
549 guarantee(!is_gc_active(), "collection is not reentrant");
550
551 if (GCLocker::check_active_before_gc()) {
552 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
553 }
554
555 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
556 soft_ref_policy()->should_clear_all_soft_refs();
557
558 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
559
560 FlagSetting fl(_is_gc_active, true);
561
562 bool complete = full && (max_generation == OldGen);
563 bool old_collects_young = complete && !ScavengeBeforeFullGC;
564 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
565
566 const PreGenGCValues pre_gc_values = get_pre_gc_values();
567
568 bool run_verification = total_collections() >= VerifyGCStartAt;
569 bool prepared_for_verification = false;
570 bool do_full_collection = false;
571
572 if (do_young_collection) {
573 GCIdMark gc_id_mark;
574 GCTraceCPUTime tcpu;
575 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true);
576
577 print_heap_before_gc();
578
579 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
580 prepare_for_verify();
581 prepared_for_verification = true;
582 }
583
584 gc_prologue(complete);
585 increment_total_collections(complete);
586
587 collect_generation(_young_gen,
588 full,
589 size,
590 is_tlab,
591 run_verification && VerifyGCLevel <= 0,
592 do_clear_all_soft_refs,
593 false);
594
595 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
596 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
597 // Allocation request was met by young GC.
598 size = 0;
599 }
600
601 // Ask if young collection is enough. If so, do the final steps for young collection,
602 // and fallthrough to the end.
603 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
604 if (!do_full_collection) {
605 // Adjust generation sizes.
606 _young_gen->compute_new_size();
607
608 print_heap_change(pre_gc_values);
609
610 // Track memory usage and detect low memory after GC finishes
611 MemoryService::track_memory_usage();
612
613 gc_epilogue(complete);
614 }
615
616 print_heap_after_gc();
617
618 } else {
619 // No young collection, ask if we need to perform Full collection.
620 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
621 }
622
623 if (do_full_collection) {
624 GCIdMark gc_id_mark;
625 GCTraceCPUTime tcpu;
626 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
627
628 print_heap_before_gc();
629
630 if (!prepared_for_verification && run_verification &&
631 VerifyGCLevel <= 1 && VerifyBeforeGC) {
632 prepare_for_verify();
633 }
634
635 if (!do_young_collection) {
636 gc_prologue(complete);
637 increment_total_collections(complete);
638 }
639
640 // Accounting quirk: total full collections would be incremented when "complete"
641 // is set, by calling increment_total_collections above. However, we also need to
642 // account Full collections that had "complete" unset.
643 if (!complete) {
644 increment_total_full_collections();
645 }
646
647 collect_generation(_old_gen,
648 full,
649 size,
650 is_tlab,
651 run_verification && VerifyGCLevel <= 1,
652 do_clear_all_soft_refs,
653 true);
654
655 // Adjust generation sizes.
656 _old_gen->compute_new_size();
657 _young_gen->compute_new_size();
658
659 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
660 ClassLoaderDataGraph::purge();
661 MetaspaceUtils::verify_metrics();
662 // Resize the metaspace capacity after full collections
663 MetaspaceGC::compute_new_size();
664 update_full_collections_completed();
665
666 print_heap_change(pre_gc_values);
667
668 // Track memory usage and detect low memory after GC finishes
669 MemoryService::track_memory_usage();
670
671 // Need to tell the epilogue code we are done with Full GC, regardless what was
672 // the initial value for "complete" flag.
673 gc_epilogue(true);
674
675 BiasedLocking::restore_marks();
676
677 print_heap_after_gc();
678 }
679
680 #ifdef TRACESPINNING
681 TaskTerminator::print_termination_counts();
682 #endif
683 }
684
685 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
686 GenCollectedHeap::GenerationType max_gen) const {
687 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
688 }
689
690 void GenCollectedHeap::register_nmethod(nmethod* nm) {
691 ScavengableNMethods::register_nmethod(nm);
692 }
693
694 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
695 ScavengableNMethods::unregister_nmethod(nm);
696 }
697
698 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
699 ScavengableNMethods::verify_nmethod(nm);
700 }
701
702 void GenCollectedHeap::flush_nmethod(nmethod* nm) {
703 // Do nothing.
704 }
705
706 void GenCollectedHeap::prune_scavengable_nmethods() {
707 ScavengableNMethods::prune_nmethods();
708 }
709
710 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
711 GCCauseSetter x(this, GCCause::_allocation_failure);
712 HeapWord* result = NULL;
713
714 assert(size != 0, "Precondition violated");
715 if (GCLocker::is_active_and_needs_gc()) {
716 // GC locker is active; instead of a collection we will attempt
717 // to expand the heap, if there's room for expansion.
718 if (!is_maximal_no_gc()) {
719 result = expand_heap_and_allocate(size, is_tlab);
720 }
721 return result; // Could be null if we are out of space.
722 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
723 // Do an incremental collection.
724 do_collection(false, // full
725 false, // clear_all_soft_refs
726 size, // size
727 is_tlab, // is_tlab
728 GenCollectedHeap::OldGen); // max_generation
729 } else {
730 log_trace(gc)(" :: Trying full because partial may fail :: ");
731 // Try a full collection; see delta for bug id 6266275
732 // for the original code and why this has been simplified
733 // with from-space allocation criteria modified and
734 // such allocation moved out of the safepoint path.
735 do_collection(true, // full
736 false, // clear_all_soft_refs
737 size, // size
738 is_tlab, // is_tlab
739 GenCollectedHeap::OldGen); // max_generation
740 }
741
742 result = attempt_allocation(size, is_tlab, false /*first_only*/);
743
744 if (result != NULL) {
745 assert(is_in_reserved(result), "result not in heap");
746 return result;
747 }
748
749 // OK, collection failed, try expansion.
750 result = expand_heap_and_allocate(size, is_tlab);
751 if (result != NULL) {
752 return result;
753 }
754
755 // If we reach this point, we're really out of memory. Try every trick
756 // we can to reclaim memory. Force collection of soft references. Force
757 // a complete compaction of the heap. Any additional methods for finding
758 // free memory should be here, especially if they are expensive. If this
759 // attempt fails, an OOM exception will be thrown.
760 {
761 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
762
763 do_collection(true, // full
764 true, // clear_all_soft_refs
765 size, // size
766 is_tlab, // is_tlab
767 GenCollectedHeap::OldGen); // max_generation
768 }
769
770 result = attempt_allocation(size, is_tlab, false /* first_only */);
771 if (result != NULL) {
772 assert(is_in_reserved(result), "result not in heap");
773 return result;
774 }
775
776 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
777 "Flag should have been handled and cleared prior to this point");
778
779 // What else? We might try synchronous finalization later. If the total
780 // space available is large enough for the allocation, then a more
781 // complete compaction phase than we've tried so far might be
782 // appropriate.
783 return NULL;
784 }
785
786 #ifdef ASSERT
787 class AssertNonScavengableClosure: public OopClosure {
788 public:
789 virtual void do_oop(oop* p) {
790 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
791 "Referent should not be scavengable."); }
792 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
793 };
794 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
795 #endif
796
797 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
798 ScanningOption so,
799 OopClosure* strong_roots,
800 CLDClosure* strong_cld_closure,
801 CLDClosure* weak_cld_closure,
802 CodeBlobToOopClosure* code_roots) {
803 // General roots.
804 assert(code_roots != NULL, "code root closure should always be set");
805 // _n_termination for _process_strong_tasks should be set up stream
806 // in a method not running in a GC worker. Otherwise the GC worker
807 // could be trying to change the termination condition while the task
808 // is executing in another GC worker.
809
810 if (_process_strong_tasks->try_claim_task(GCH_PS_ClassLoaderDataGraph_oops_do)) {
811 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
812 }
813
814 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
815 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
816
817 bool is_par = scope->n_threads() > 1;
818 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
819
820 if (_process_strong_tasks->try_claim_task(GCH_PS_Universe_oops_do)) {
821 Universe::oops_do(strong_roots);
822 }
823 // Global (strong) JNI handles
824 if (_process_strong_tasks->try_claim_task(GCH_PS_JNIHandles_oops_do)) {
825 JNIHandles::oops_do(strong_roots);
826 }
827
828 if (_process_strong_tasks->try_claim_task(GCH_PS_ObjectSynchronizer_oops_do)) {
829 ObjectSynchronizer::oops_do(strong_roots);
830 }
831 if (_process_strong_tasks->try_claim_task(GCH_PS_Management_oops_do)) {
832 Management::oops_do(strong_roots);
833 }
834 if (_process_strong_tasks->try_claim_task(GCH_PS_jvmti_oops_do)) {
835 JvmtiExport::oops_do(strong_roots);
836 }
837 #if INCLUDE_AOT
838 if (UseAOT && _process_strong_tasks->try_claim_task(GCH_PS_aot_oops_do)) {
839 AOTLoader::oops_do(strong_roots);
840 }
841 #endif
842 if (_process_strong_tasks->try_claim_task(GCH_PS_SystemDictionary_oops_do)) {
843 SystemDictionary::oops_do(strong_roots);
844 }
845
846 if (_process_strong_tasks->try_claim_task(GCH_PS_CodeCache_oops_do)) {
847 if (so & SO_ScavengeCodeCache) {
848 assert(code_roots != NULL, "must supply closure for code cache");
849
850 // We only visit parts of the CodeCache when scavenging.
851 ScavengableNMethods::nmethods_do(code_roots);
852 }
853 if (so & SO_AllCodeCache) {
854 assert(code_roots != NULL, "must supply closure for code cache");
855
856 // CMSCollector uses this to do intermediate-strength collections.
857 // We scan the entire code cache, since CodeCache::do_unloading is not called.
858 CodeCache::blobs_do(code_roots);
859 }
860 // Verify that the code cache contents are not subject to
861 // movement by a scavenging collection.
862 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
863 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
864 }
865 }
866
867 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
868 OopsInGenClosure* root_closure,
869 OopsInGenClosure* old_gen_closure,
870 CLDClosure* cld_closure) {
871 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
872
873 process_roots(scope, SO_ScavengeCodeCache, root_closure,
874 cld_closure, cld_closure, &mark_code_closure);
875
876 if (_process_strong_tasks->try_claim_task(GCH_PS_younger_gens)) {
877 root_closure->reset_generation();
878 }
879
880 // When collection is parallel, all threads get to cooperate to do
881 // old generation scanning.
882 old_gen_closure->set_generation(_old_gen);
883 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
884 old_gen_closure->reset_generation();
885
886 _process_strong_tasks->all_tasks_completed(scope->n_threads());
887 }
888
889 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
890 bool is_adjust_phase,
891 ScanningOption so,
892 bool only_strong_roots,
893 OopsInGenClosure* root_closure,
894 CLDClosure* cld_closure) {
895 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
896 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
897
898 process_roots(scope, so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
899 _process_strong_tasks->all_tasks_completed(scope->n_threads());
900 }
901
902 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
903 WeakProcessor::oops_do(root_closure);
904 _young_gen->ref_processor()->weak_oops_do(root_closure);
905 _old_gen->ref_processor()->weak_oops_do(root_closure);
906 }
907
908 bool GenCollectedHeap::no_allocs_since_save_marks() {
909 return _young_gen->no_allocs_since_save_marks() &&
910 _old_gen->no_allocs_since_save_marks();
911 }
912
913 bool GenCollectedHeap::supports_inline_contig_alloc() const {
914 return _young_gen->supports_inline_contig_alloc();
915 }
916
917 HeapWord* volatile* GenCollectedHeap::top_addr() const {
918 return _young_gen->top_addr();
919 }
920
921 HeapWord** GenCollectedHeap::end_addr() const {
922 return _young_gen->end_addr();
923 }
924
925 // public collection interfaces
926
927 void GenCollectedHeap::collect(GCCause::Cause cause) {
928 if ((cause == GCCause::_wb_young_gc) ||
929 (cause == GCCause::_gc_locker)) {
930 // Young collection for WhiteBox or GCLocker.
931 collect(cause, YoungGen);
932 } else {
933 #ifdef ASSERT
934 if (cause == GCCause::_scavenge_alot) {
935 // Young collection only.
936 collect(cause, YoungGen);
937 } else {
938 // Stop-the-world full collection.
939 collect(cause, OldGen);
940 }
941 #else
942 // Stop-the-world full collection.
943 collect(cause, OldGen);
944 #endif
945 }
946 }
947
948 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
949 // The caller doesn't have the Heap_lock
950 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
951 MutexLocker ml(Heap_lock);
952 collect_locked(cause, max_generation);
953 }
954
955 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
956 // The caller has the Heap_lock
957 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
958 collect_locked(cause, OldGen);
959 }
960
961 // this is the private collection interface
962 // The Heap_lock is expected to be held on entry.
963
964 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
965 // Read the GC count while holding the Heap_lock
966 unsigned int gc_count_before = total_collections();
967 unsigned int full_gc_count_before = total_full_collections();
968
969 if (GCLocker::should_discard(cause, gc_count_before)) {
970 return;
971 }
972
973 {
974 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
975 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
976 cause, max_generation);
977 VMThread::execute(&op);
978 }
979 }
980
981 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
982 do_full_collection(clear_all_soft_refs, OldGen);
983 }
984
985 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
986 GenerationType last_generation) {
987 do_collection(true, // full
988 clear_all_soft_refs, // clear_all_soft_refs
989 0, // size
990 false, // is_tlab
991 last_generation); // last_generation
992 // Hack XXX FIX ME !!!
993 // A scavenge may not have been attempted, or may have
994 // been attempted and failed, because the old gen was too full
995 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
996 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
997 // This time allow the old gen to be collected as well
998 do_collection(true, // full
999 clear_all_soft_refs, // clear_all_soft_refs
1000 0, // size
1001 false, // is_tlab
1002 OldGen); // last_generation
1003 }
1004 }
1005
1006 bool GenCollectedHeap::is_in_young(oop p) {
1007 bool result = cast_from_oop<HeapWord*>(p) < _old_gen->reserved().start();
1008 assert(result == _young_gen->is_in_reserved(p),
1009 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1010 return result;
1011 }
1012
1013 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1014 bool GenCollectedHeap::is_in(const void* p) const {
1015 return _young_gen->is_in(p) || _old_gen->is_in(p);
1016 }
1017
1018 #ifdef ASSERT
1019 // Don't implement this by using is_in_young(). This method is used
1020 // in some cases to check that is_in_young() is correct.
1021 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1022 assert(is_in_reserved(p) || p == NULL,
1023 "Does not work if address is non-null and outside of the heap");
1024 return p < _young_gen->reserved().end() && p != NULL;
1025 }
1026 #endif
1027
1028 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
1029 _young_gen->oop_iterate(cl);
1030 _old_gen->oop_iterate(cl);
1031 }
1032
1033 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1034 _young_gen->object_iterate(cl);
1035 _old_gen->object_iterate(cl);
1036 }
1037
1038 Space* GenCollectedHeap::space_containing(const void* addr) const {
1039 Space* res = _young_gen->space_containing(addr);
1040 if (res != NULL) {
1041 return res;
1042 }
1043 res = _old_gen->space_containing(addr);
1044 assert(res != NULL, "Could not find containing space");
1045 return res;
1046 }
1047
1048 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1049 assert(is_in_reserved(addr), "block_start of address outside of heap");
1050 if (_young_gen->is_in_reserved(addr)) {
1051 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1052 return _young_gen->block_start(addr);
1053 }
1054
1055 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1056 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1057 return _old_gen->block_start(addr);
1058 }
1059
1060 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1061 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1062 assert(block_start(addr) == addr, "addr must be a block start");
1063 if (_young_gen->is_in_reserved(addr)) {
1064 return _young_gen->block_is_obj(addr);
1065 }
1066
1067 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1068 return _old_gen->block_is_obj(addr);
1069 }
1070
1071 bool GenCollectedHeap::supports_tlab_allocation() const {
1072 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1073 return _young_gen->supports_tlab_allocation();
1074 }
1075
1076 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1077 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1078 if (_young_gen->supports_tlab_allocation()) {
1079 return _young_gen->tlab_capacity();
1080 }
1081 return 0;
1082 }
1083
1084 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1085 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1086 if (_young_gen->supports_tlab_allocation()) {
1087 return _young_gen->tlab_used();
1088 }
1089 return 0;
1090 }
1091
1092 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1093 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1094 if (_young_gen->supports_tlab_allocation()) {
1095 return _young_gen->unsafe_max_tlab_alloc();
1096 }
1097 return 0;
1098 }
1099
1100 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1101 size_t requested_size,
1102 size_t* actual_size) {
1103 bool gc_overhead_limit_was_exceeded;
1104 HeapWord* result = mem_allocate_work(requested_size /* size */,
1105 true /* is_tlab */,
1106 &gc_overhead_limit_was_exceeded);
1107 if (result != NULL) {
1108 *actual_size = requested_size;
1109 }
1110
1111 return result;
1112 }
1113
1114 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1115 // from the list headed by "*prev_ptr".
1116 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1117 bool first = true;
1118 size_t min_size = 0; // "first" makes this conceptually infinite.
1119 ScratchBlock **smallest_ptr, *smallest;
1120 ScratchBlock *cur = *prev_ptr;
1121 while (cur) {
1122 assert(*prev_ptr == cur, "just checking");
1123 if (first || cur->num_words < min_size) {
1124 smallest_ptr = prev_ptr;
1125 smallest = cur;
1126 min_size = smallest->num_words;
1127 first = false;
1128 }
1129 prev_ptr = &cur->next;
1130 cur = cur->next;
1131 }
1132 smallest = *smallest_ptr;
1133 *smallest_ptr = smallest->next;
1134 return smallest;
1135 }
1136
1137 // Sort the scratch block list headed by res into decreasing size order,
1138 // and set "res" to the result.
1139 static void sort_scratch_list(ScratchBlock*& list) {
1140 ScratchBlock* sorted = NULL;
1141 ScratchBlock* unsorted = list;
1142 while (unsorted) {
1143 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1144 smallest->next = sorted;
1145 sorted = smallest;
1146 }
1147 list = sorted;
1148 }
1149
1150 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1151 size_t max_alloc_words) {
1152 ScratchBlock* res = NULL;
1153 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1154 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1155 sort_scratch_list(res);
1156 return res;
1157 }
1158
1159 void GenCollectedHeap::release_scratch() {
1160 _young_gen->reset_scratch();
1161 _old_gen->reset_scratch();
1162 }
1163
1164 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1165 void do_generation(Generation* gen) {
1166 gen->prepare_for_verify();
1167 }
1168 };
1169
1170 void GenCollectedHeap::prepare_for_verify() {
1171 ensure_parsability(false); // no need to retire TLABs
1172 GenPrepareForVerifyClosure blk;
1173 generation_iterate(&blk, false);
1174 }
1175
1176 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1177 bool old_to_young) {
1178 if (old_to_young) {
1179 cl->do_generation(_old_gen);
1180 cl->do_generation(_young_gen);
1181 } else {
1182 cl->do_generation(_young_gen);
1183 cl->do_generation(_old_gen);
1184 }
1185 }
1186
1187 bool GenCollectedHeap::is_maximal_no_gc() const {
1188 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1189 }
1190
1191 void GenCollectedHeap::save_marks() {
1192 _young_gen->save_marks();
1193 _old_gen->save_marks();
1194 }
1195
1196 GenCollectedHeap* GenCollectedHeap::heap() {
1197 CollectedHeap* heap = Universe::heap();
1198 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1199 assert(heap->kind() == CollectedHeap::Serial, "Invalid name");
1200 return (GenCollectedHeap*) heap;
1201 }
1202
1203 #if INCLUDE_SERIALGC
1204 void GenCollectedHeap::prepare_for_compaction() {
1205 // Start by compacting into same gen.
1206 CompactPoint cp(_old_gen);
1207 _old_gen->prepare_for_compaction(&cp);
1208 _young_gen->prepare_for_compaction(&cp);
1209 }
1210 #endif // INCLUDE_SERIALGC
1211
1212 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1213 log_debug(gc, verify)("%s", _old_gen->name());
1214 _old_gen->verify();
1215
1216 log_debug(gc, verify)("%s", _old_gen->name());
1217 _young_gen->verify();
1218
1219 log_debug(gc, verify)("RemSet");
1220 rem_set()->verify();
1221 }
1222
1223 void GenCollectedHeap::print_on(outputStream* st) const {
1224 _young_gen->print_on(st);
1225 _old_gen->print_on(st);
1226 MetaspaceUtils::print_on(st);
1227 }
1228
1229 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1230 }
1231
1232 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1233 }
1234
1235 bool GenCollectedHeap::print_location(outputStream* st, void* addr) const {
1236 return BlockLocationPrinter<GenCollectedHeap>::print_location(st, addr);
1237 }
1238
1239 void GenCollectedHeap::print_tracing_info() const {
1240 if (log_is_enabled(Debug, gc, heap, exit)) {
1241 LogStreamHandle(Debug, gc, heap, exit) lsh;
1242 _young_gen->print_summary_info_on(&lsh);
1243 _old_gen->print_summary_info_on(&lsh);
1244 }
1245 }
1246
1247 void GenCollectedHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const {
1248 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen();
1249
1250 log_info(gc, heap)(HEAP_CHANGE_FORMAT" "
1251 HEAP_CHANGE_FORMAT" "
1252 HEAP_CHANGE_FORMAT,
1253 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(),
1254 pre_gc_values.young_gen_used(),
1255 pre_gc_values.young_gen_capacity(),
1256 def_new_gen->used(),
1257 def_new_gen->capacity()),
1258 HEAP_CHANGE_FORMAT_ARGS("Eden",
1259 pre_gc_values.eden_used(),
1260 pre_gc_values.eden_capacity(),
1261 def_new_gen->eden()->used(),
1262 def_new_gen->eden()->capacity()),
1263 HEAP_CHANGE_FORMAT_ARGS("From",
1264 pre_gc_values.from_used(),
1265 pre_gc_values.from_capacity(),
1266 def_new_gen->from()->used(),
1267 def_new_gen->from()->capacity()));
1268 log_info(gc, heap)(HEAP_CHANGE_FORMAT,
1269 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(),
1270 pre_gc_values.old_gen_used(),
1271 pre_gc_values.old_gen_capacity(),
1272 old_gen()->used(),
1273 old_gen()->capacity()));
1274 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes());
1275 }
1276
1277 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1278 private:
1279 bool _full;
1280 public:
1281 void do_generation(Generation* gen) {
1282 gen->gc_prologue(_full);
1283 }
1284 GenGCPrologueClosure(bool full) : _full(full) {};
1285 };
1286
1287 void GenCollectedHeap::gc_prologue(bool full) {
1288 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1289
1290 // Fill TLAB's and such
1291 ensure_parsability(true); // retire TLABs
1292
1293 // Walk generations
1294 GenGCPrologueClosure blk(full);
1295 generation_iterate(&blk, false); // not old-to-young.
1296 };
1297
1298 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1299 private:
1300 bool _full;
1301 public:
1302 void do_generation(Generation* gen) {
1303 gen->gc_epilogue(_full);
1304 }
1305 GenGCEpilogueClosure(bool full) : _full(full) {};
1306 };
1307
1308 void GenCollectedHeap::gc_epilogue(bool full) {
1309 #if COMPILER2_OR_JVMCI
1310 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1311 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1312 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1313 #endif // COMPILER2_OR_JVMCI
1314
1315 resize_all_tlabs();
1316
1317 GenGCEpilogueClosure blk(full);
1318 generation_iterate(&blk, false); // not old-to-young.
1319
1320 if (!CleanChunkPoolAsync) {
1321 Chunk::clean_chunk_pool();
1322 }
1323
1324 MetaspaceCounters::update_performance_counters();
1325 CompressedClassSpaceCounters::update_performance_counters();
1326 };
1327
1328 #ifndef PRODUCT
1329 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1330 private:
1331 public:
1332 void do_generation(Generation* gen) {
1333 gen->record_spaces_top();
1334 }
1335 };
1336
1337 void GenCollectedHeap::record_gen_tops_before_GC() {
1338 if (ZapUnusedHeapArea) {
1339 GenGCSaveTopsBeforeGCClosure blk;
1340 generation_iterate(&blk, false); // not old-to-young.
1341 }
1342 }
1343 #endif // not PRODUCT
1344
1345 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1346 public:
1347 void do_generation(Generation* gen) {
1348 gen->ensure_parsability();
1349 }
1350 };
1351
1352 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1353 CollectedHeap::ensure_parsability(retire_tlabs);
1354 GenEnsureParsabilityClosure ep_cl;
1355 generation_iterate(&ep_cl, false);
1356 }
1357
1358 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1359 oop obj,
1360 size_t obj_size) {
1361 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1362 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1363 HeapWord* result = NULL;
1364
1365 result = old_gen->expand_and_allocate(obj_size, false);
1366
1367 if (result != NULL) {
1368 Copy::aligned_disjoint_words(cast_from_oop<HeapWord*>(obj), result, obj_size);
1369 }
1370 return oop(result);
1371 }
1372
1373 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1374 jlong _time; // in ms
1375 jlong _now; // in ms
1376
1377 public:
1378 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1379
1380 jlong time() { return _time; }
1381
1382 void do_generation(Generation* gen) {
1383 _time = MIN2(_time, gen->time_of_last_gc(_now));
1384 }
1385 };
1386
1387 jlong GenCollectedHeap::millis_since_last_gc() {
1388 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1389 // provided the underlying platform provides such a time source
1390 // (and it is bug free). So we still have to guard against getting
1391 // back a time later than 'now'.
1392 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1393 GenTimeOfLastGCClosure tolgc_cl(now);
1394 // iterate over generations getting the oldest
1395 // time that a generation was collected
1396 generation_iterate(&tolgc_cl, false);
1397
1398 jlong retVal = now - tolgc_cl.time();
1399 if (retVal < 0) {
1400 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1401 ". returning zero instead.", retVal);
1402 return 0;
1403 }
1404 return retVal;
1405 }