1 /*
2 * Copyright (c) 2000, 2019, 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/gcVMOperations.hpp"
46 #include "gc/shared/genCollectedHeap.hpp"
47 #include "gc/shared/genOopClosures.inline.hpp"
48 #include "gc/shared/generationSpec.hpp"
49 #include "gc/shared/oopStorageParState.inline.hpp"
50 #include "gc/shared/scavengableNMethods.hpp"
51 #include "gc/shared/space.hpp"
52 #include "gc/shared/strongRootsScope.hpp"
53 #include "gc/shared/weakProcessor.hpp"
54 #include "gc/shared/workgroup.hpp"
55 #include "memory/filemap.hpp"
56 #include "memory/metaspaceCounters.hpp"
57 #include "memory/resourceArea.hpp"
58 #include "oops/oop.inline.hpp"
59 #include "runtime/biasedLocking.hpp"
60 #include "runtime/flags/flagSetting.hpp"
61 #include "runtime/handles.hpp"
62 #include "runtime/handles.inline.hpp"
63 #include "runtime/java.hpp"
64 #include "runtime/vmThread.hpp"
65 #include "services/management.hpp"
66 #include "services/memoryService.hpp"
67 #include "utilities/debug.hpp"
68 #include "utilities/formatBuffer.hpp"
69 #include "utilities/macros.hpp"
70 #include "utilities/stack.inline.hpp"
71 #include "utilities/vmError.hpp"
72
73 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy,
74 Generation::Name young,
75 Generation::Name old,
76 const char* policy_counters_name) :
77 CollectedHeap(),
78 _young_gen_spec(new GenerationSpec(young,
79 policy->initial_young_size(),
80 policy->max_young_size(),
81 policy->gen_alignment())),
82 _old_gen_spec(new GenerationSpec(old,
83 policy->initial_old_size(),
84 policy->max_old_size(),
85 policy->gen_alignment())),
86 _rem_set(NULL),
87 _gen_policy(policy),
88 _soft_ref_gen_policy(),
89 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
90 _full_collections_completed(0),
91 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)) {
92 }
93
94 jint GenCollectedHeap::initialize() {
95 // While there are no constraints in the GC code that HeapWordSize
96 // be any particular value, there are multiple other areas in the
97 // system which believe this to be true (e.g. oop->object_size in some
98 // cases incorrectly returns the size in wordSize units rather than
99 // HeapWordSize).
100 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
101
102 // Allocate space for the heap.
103
104 char* heap_address;
105 ReservedSpace heap_rs;
106
107 size_t heap_alignment = collector_policy()->heap_alignment();
108
109 heap_address = allocate(heap_alignment, &heap_rs);
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((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
118
119 _rem_set = create_rem_set(reserved_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 heap_rs = heap_rs.last_part(_young_gen_spec->max_size());
128
129 ReservedSpace old_rs = heap_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 char* GenCollectedHeap::allocate(size_t alignment,
152 ReservedSpace* heap_rs){
153 // Now figure out the total size.
154 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
155 assert(alignment % pageSize == 0, "Must be");
156
157 // Check for overflow.
158 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
159 if (total_reserved < _young_gen_spec->max_size()) {
160 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
161 "the maximum representable size");
162 }
163 assert(total_reserved % alignment == 0,
164 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
165 SIZE_FORMAT, total_reserved, alignment);
166
167 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
168
169 os::trace_page_sizes("Heap",
170 collector_policy()->min_heap_byte_size(),
171 total_reserved,
172 alignment,
173 heap_rs->base(),
174 heap_rs->size());
175
176 return heap_rs->base();
177 }
178
179 namespace {
180 class GenIsScavengable : public BoolObjectClosure {
181 public:
182 bool do_object_b(oop obj) {
183 return GenCollectedHeap::heap()->is_in_young(obj);
184 }
185 };
186
187 GenIsScavengable _is_scavengable;
188 }
189
190 void GenCollectedHeap::post_initialize() {
191 CollectedHeap::post_initialize();
192 ref_processing_init();
193
194 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
195
196 initialize_size_policy(def_new_gen->eden()->capacity(),
197 _old_gen->capacity(),
198 def_new_gen->from()->capacity());
199
200 MarkSweep::initialize();
201
202 ScavengableNMethods::initialize(&_is_scavengable);
203 }
204
205 void GenCollectedHeap::ref_processing_init() {
206 _young_gen->ref_processor_init();
207 _old_gen->ref_processor_init();
208 }
209
210 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
211 return _young_gen_spec;
212 }
213
214 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
215 return _old_gen_spec;
216 }
217
218 size_t GenCollectedHeap::capacity() const {
219 return _young_gen->capacity() + _old_gen->capacity();
220 }
221
222 size_t GenCollectedHeap::used() const {
223 return _young_gen->used() + _old_gen->used();
224 }
225
226 void GenCollectedHeap::save_used_regions() {
227 _old_gen->save_used_region();
228 _young_gen->save_used_region();
229 }
230
231 size_t GenCollectedHeap::max_capacity() const {
232 return _young_gen->max_capacity() + _old_gen->max_capacity();
233 }
234
235 // Update the _full_collections_completed counter
236 // at the end of a stop-world full GC.
237 unsigned int GenCollectedHeap::update_full_collections_completed() {
238 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
239 assert(_full_collections_completed <= _total_full_collections,
240 "Can't complete more collections than were started");
241 _full_collections_completed = _total_full_collections;
242 ml.notify_all();
243 return _full_collections_completed;
244 }
245
246 // Update the _full_collections_completed counter, as appropriate,
247 // at the end of a concurrent GC cycle. Note the conditional update
248 // below to allow this method to be called by a concurrent collector
249 // without synchronizing in any manner with the VM thread (which
250 // may already have initiated a STW full collection "concurrently").
251 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
252 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
253 assert((_full_collections_completed <= _total_full_collections) &&
254 (count <= _total_full_collections),
255 "Can't complete more collections than were started");
256 if (count > _full_collections_completed) {
257 _full_collections_completed = count;
258 ml.notify_all();
259 }
260 return _full_collections_completed;
261 }
262
263 // Return true if any of the following is true:
264 // . the allocation won't fit into the current young gen heap
265 // . gc locker is occupied (jni critical section)
266 // . heap memory is tight -- the most recent previous collection
267 // was a full collection because a partial collection (would
268 // have) failed and is likely to fail again
269 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
270 size_t young_capacity = _young_gen->capacity_before_gc();
271 return (word_size > heap_word_size(young_capacity))
272 || GCLocker::is_active_and_needs_gc()
273 || incremental_collection_failed();
274 }
275
276 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
277 HeapWord* result = NULL;
278 if (_old_gen->should_allocate(size, is_tlab)) {
279 result = _old_gen->expand_and_allocate(size, is_tlab);
280 }
281 if (result == NULL) {
282 if (_young_gen->should_allocate(size, is_tlab)) {
283 result = _young_gen->expand_and_allocate(size, is_tlab);
284 }
285 }
286 assert(result == NULL || is_in_reserved(result), "result not in heap");
287 return result;
288 }
289
290 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
291 bool is_tlab,
292 bool* gc_overhead_limit_was_exceeded) {
293 // In general gc_overhead_limit_was_exceeded should be false so
294 // set it so here and reset it to true only if the gc time
295 // limit is being exceeded as checked below.
296 *gc_overhead_limit_was_exceeded = false;
297
298 HeapWord* result = NULL;
299
300 // Loop until the allocation is satisfied, or unsatisfied after GC.
301 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
302 HandleMark hm; // Discard any handles allocated in each iteration.
303
304 // First allocation attempt is lock-free.
305 Generation *young = _young_gen;
306 assert(young->supports_inline_contig_alloc(),
307 "Otherwise, must do alloc within heap lock");
308 if (young->should_allocate(size, is_tlab)) {
309 result = young->par_allocate(size, is_tlab);
310 if (result != NULL) {
311 assert(is_in_reserved(result), "result not in heap");
312 return result;
313 }
314 }
315 uint gc_count_before; // Read inside the Heap_lock locked region.
316 {
317 MutexLocker ml(Heap_lock);
318 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
319 // Note that only large objects get a shot at being
320 // allocated in later generations.
321 bool first_only = !should_try_older_generation_allocation(size);
322
323 result = attempt_allocation(size, is_tlab, first_only);
324 if (result != NULL) {
325 assert(is_in_reserved(result), "result not in heap");
326 return result;
327 }
328
329 if (GCLocker::is_active_and_needs_gc()) {
330 if (is_tlab) {
331 return NULL; // Caller will retry allocating individual object.
332 }
333 if (!is_maximal_no_gc()) {
334 // Try and expand heap to satisfy request.
335 result = expand_heap_and_allocate(size, is_tlab);
336 // Result could be null if we are out of space.
337 if (result != NULL) {
338 return result;
339 }
340 }
341
342 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
343 return NULL; // We didn't get to do a GC and we didn't get any memory.
344 }
345
346 // If this thread is not in a jni critical section, we stall
347 // the requestor until the critical section has cleared and
348 // GC allowed. When the critical section clears, a GC is
349 // initiated by the last thread exiting the critical section; so
350 // we retry the allocation sequence from the beginning of the loop,
351 // rather than causing more, now probably unnecessary, GC attempts.
352 JavaThread* jthr = JavaThread::current();
353 if (!jthr->in_critical()) {
354 MutexUnlocker mul(Heap_lock);
355 // Wait for JNI critical section to be exited
356 GCLocker::stall_until_clear();
357 gclocker_stalled_count += 1;
358 continue;
359 } else {
360 if (CheckJNICalls) {
361 fatal("Possible deadlock due to allocating while"
362 " in jni critical section");
363 }
364 return NULL;
365 }
366 }
367
368 // Read the gc count while the heap lock is held.
369 gc_count_before = total_collections();
370 }
371
372 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
373 VMThread::execute(&op);
374 if (op.prologue_succeeded()) {
375 result = op.result();
376 if (op.gc_locked()) {
377 assert(result == NULL, "must be NULL if gc_locked() is true");
378 continue; // Retry and/or stall as necessary.
379 }
380
381 // Allocation has failed and a collection
382 // has been done. If the gc time limit was exceeded the
383 // this time, return NULL so that an out-of-memory
384 // will be thrown. Clear gc_overhead_limit_exceeded
385 // so that the overhead exceeded does not persist.
386
387 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
388 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
389
390 if (limit_exceeded && softrefs_clear) {
391 *gc_overhead_limit_was_exceeded = true;
392 size_policy()->set_gc_overhead_limit_exceeded(false);
393 if (op.result() != NULL) {
394 CollectedHeap::fill_with_object(op.result(), size);
395 }
396 return NULL;
397 }
398 assert(result == NULL || is_in_reserved(result),
399 "result not in heap");
400 return result;
401 }
402
403 // Give a warning if we seem to be looping forever.
404 if ((QueuedAllocationWarningCount > 0) &&
405 (try_count % QueuedAllocationWarningCount == 0)) {
406 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
407 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
408 }
409 }
410 }
411
412 #ifndef PRODUCT
413 // Override of memory state checking method in CollectedHeap:
414 // Some collectors (CMS for example) can't have badHeapWordVal written
415 // in the first two words of an object. (For instance , in the case of
416 // CMS these words hold state used to synchronize between certain
417 // (concurrent) GC steps and direct allocating mutators.)
418 // The skip_header_HeapWords() method below, allows us to skip
419 // over the requisite number of HeapWord's. Note that (for
420 // generational collectors) this means that those many words are
421 // skipped in each object, irrespective of the generation in which
422 // that object lives. The resultant loss of precision seems to be
423 // harmless and the pain of avoiding that imprecision appears somewhat
424 // higher than we are prepared to pay for such rudimentary debugging
425 // support.
426 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
427 size_t size) {
428 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
429 // We are asked to check a size in HeapWords,
430 // but the memory is mangled in juint words.
431 juint* start = (juint*) (addr + skip_header_HeapWords());
432 juint* end = (juint*) (addr + size);
433 for (juint* slot = start; slot < end; slot += 1) {
434 assert(*slot == badHeapWordVal,
435 "Found non badHeapWordValue in pre-allocation check");
436 }
437 }
438 }
439 #endif
440
441 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
442 bool is_tlab,
443 bool first_only) {
444 HeapWord* res = NULL;
445
446 if (_young_gen->should_allocate(size, is_tlab)) {
447 res = _young_gen->allocate(size, is_tlab);
448 if (res != NULL || first_only) {
449 return res;
450 }
451 }
452
453 if (_old_gen->should_allocate(size, is_tlab)) {
454 res = _old_gen->allocate(size, is_tlab);
455 }
456
457 return res;
458 }
459
460 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
461 bool* gc_overhead_limit_was_exceeded) {
462 return mem_allocate_work(size,
463 false /* is_tlab */,
464 gc_overhead_limit_was_exceeded);
465 }
466
467 bool GenCollectedHeap::must_clear_all_soft_refs() {
468 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
469 _gc_cause == GCCause::_wb_full_gc;
470 }
471
472 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
473 bool is_tlab, bool run_verification, bool clear_soft_refs,
474 bool restore_marks_for_biased_locking) {
475 FormatBuffer<> title("Collect gen: %s", gen->short_name());
476 GCTraceTime(Trace, gc, phases) t1(title);
477 TraceCollectorStats tcs(gen->counters());
478 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
479
480 gen->stat_record()->invocations++;
481 gen->stat_record()->accumulated_time.start();
482
483 // Must be done anew before each collection because
484 // a previous collection will do mangling and will
485 // change top of some spaces.
486 record_gen_tops_before_GC();
487
488 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
489
490 if (run_verification && VerifyBeforeGC) {
491 HandleMark hm; // Discard invalid handles created during verification
492 Universe::verify("Before GC");
493 }
494 COMPILER2_PRESENT(DerivedPointerTable::clear());
495
496 if (restore_marks_for_biased_locking) {
497 // We perform this mark word preservation work lazily
498 // because it's only at this point that we know whether we
499 // absolutely have to do it; we want to avoid doing it for
500 // scavenge-only collections where it's unnecessary
501 BiasedLocking::preserve_marks();
502 }
503
504 // Do collection work
505 {
506 // Note on ref discovery: For what appear to be historical reasons,
507 // GCH enables and disabled (by enqueing) refs discovery.
508 // In the future this should be moved into the generation's
509 // collect method so that ref discovery and enqueueing concerns
510 // are local to a generation. The collect method could return
511 // an appropriate indication in the case that notification on
512 // the ref lock was needed. This will make the treatment of
513 // weak refs more uniform (and indeed remove such concerns
514 // from GCH). XXX
515
516 HandleMark hm; // Discard invalid handles created during gc
517 save_marks(); // save marks for all gens
518 // We want to discover references, but not process them yet.
519 // This mode is disabled in process_discovered_references if the
520 // generation does some collection work, or in
521 // enqueue_discovered_references if the generation returns
522 // without doing any work.
523 ReferenceProcessor* rp = gen->ref_processor();
524 // If the discovery of ("weak") refs in this generation is
525 // atomic wrt other collectors in this configuration, we
526 // are guaranteed to have empty discovered ref lists.
527 if (rp->discovery_is_atomic()) {
528 rp->enable_discovery();
529 rp->setup_policy(clear_soft_refs);
530 } else {
531 // collect() below will enable discovery as appropriate
532 }
533 gen->collect(full, clear_soft_refs, size, is_tlab);
534 if (!rp->enqueuing_is_done()) {
535 rp->disable_discovery();
536 } else {
537 rp->set_enqueuing_is_done(false);
538 }
539 rp->verify_no_references_recorded();
540 }
541
542 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
543
544 gen->stat_record()->accumulated_time.stop();
545
546 update_gc_stats(gen, full);
547
548 if (run_verification && VerifyAfterGC) {
549 HandleMark hm; // Discard invalid handles created during verification
550 Universe::verify("After GC");
551 }
552 }
553
554 void GenCollectedHeap::do_collection(bool full,
555 bool clear_all_soft_refs,
556 size_t size,
557 bool is_tlab,
558 GenerationType max_generation) {
559 ResourceMark rm;
560 DEBUG_ONLY(Thread* my_thread = Thread::current();)
561
562 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
563 assert(my_thread->is_VM_thread() ||
564 my_thread->is_ConcurrentGC_thread(),
565 "incorrect thread type capability");
566 assert(Heap_lock->is_locked(),
567 "the requesting thread should have the Heap_lock");
568 guarantee(!is_gc_active(), "collection is not reentrant");
569
570 if (GCLocker::check_active_before_gc()) {
571 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
572 }
573
574 GCIdMark gc_id_mark;
575
576 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
577 soft_ref_policy()->should_clear_all_soft_refs();
578
579 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
580
581 const size_t metadata_prev_used = MetaspaceUtils::used_bytes();
582
583 print_heap_before_gc();
584
585 {
586 FlagSetting fl(_is_gc_active, true);
587
588 bool complete = full && (max_generation == OldGen);
589 bool old_collects_young = complete && !ScavengeBeforeFullGC;
590 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
591
592 FormatBuffer<> gc_string("%s", "Pause ");
593 if (do_young_collection) {
594 gc_string.append("Young");
595 } else {
596 gc_string.append("Full");
597 }
598
599 GCTraceCPUTime tcpu;
600 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
601
602 gc_prologue(complete);
603 increment_total_collections(complete);
604
605 size_t young_prev_used = _young_gen->used();
606 size_t old_prev_used = _old_gen->used();
607
608 bool run_verification = total_collections() >= VerifyGCStartAt;
609
610 bool prepared_for_verification = false;
611 bool collected_old = false;
612
613 if (do_young_collection) {
614 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
615 prepare_for_verify();
616 prepared_for_verification = true;
617 }
618
619 collect_generation(_young_gen,
620 full,
621 size,
622 is_tlab,
623 run_verification && VerifyGCLevel <= 0,
624 do_clear_all_soft_refs,
625 false);
626
627 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
628 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
629 // Allocation request was met by young GC.
630 size = 0;
631 }
632 }
633
634 bool must_restore_marks_for_biased_locking = false;
635
636 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
637 if (!complete) {
638 // The full_collections increment was missed above.
639 increment_total_full_collections();
640 }
641
642 if (!prepared_for_verification && run_verification &&
643 VerifyGCLevel <= 1 && VerifyBeforeGC) {
644 prepare_for_verify();
645 }
646
647 if (do_young_collection) {
648 // We did a young GC. Need a new GC id for the old GC.
649 GCIdMark gc_id_mark;
650 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
651 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
652 } else {
653 // No young GC done. Use the same GC id as was set up earlier in this method.
654 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
655 }
656
657 must_restore_marks_for_biased_locking = true;
658 collected_old = true;
659 }
660
661 // Update "complete" boolean wrt what actually transpired --
662 // for instance, a promotion failure could have led to
663 // a whole heap collection.
664 complete = complete || collected_old;
665
666 // Adjust generation sizes.
667 if (collected_old) {
668 _old_gen->compute_new_size();
669 }
670 _young_gen->compute_new_size();
671
672 if (complete) {
673 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
674 ClassLoaderDataGraph::purge();
675 MetaspaceUtils::verify_metrics();
676 // Resize the metaspace capacity after full collections
677 MetaspaceGC::compute_new_size();
678 update_full_collections_completed();
679 }
680
681 print_heap_change(young_prev_used, old_prev_used);
682 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
683
684 // Track memory usage and detect low memory after GC finishes
685 MemoryService::track_memory_usage();
686
687 gc_epilogue(complete);
688
689 if (must_restore_marks_for_biased_locking) {
690 BiasedLocking::restore_marks();
691 }
692 }
693
694 print_heap_after_gc();
695
696 #ifdef TRACESPINNING
697 ParallelTaskTerminator::print_termination_counts();
698 #endif
699 }
700
701 void GenCollectedHeap::register_nmethod(nmethod* nm) {
702 ScavengableNMethods::register_nmethod(nm);
703 }
704
705 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
706 ScavengableNMethods::unregister_nmethod(nm);
707 }
708
709 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
710 ScavengableNMethods::verify_nmethod(nm);
711 }
712
713 void GenCollectedHeap::flush_nmethod(nmethod* nm) {
714 ScavengableNMethods::flush_nmethod(nm);
715 }
716
717 void GenCollectedHeap::prune_nmethods() {
718 ScavengableNMethods::prune_nmethods();
719 }
720
721 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
722 GCCauseSetter x(this, GCCause::_allocation_failure);
723 HeapWord* result = NULL;
724
725 assert(size != 0, "Precondition violated");
726 if (GCLocker::is_active_and_needs_gc()) {
727 // GC locker is active; instead of a collection we will attempt
728 // to expand the heap, if there's room for expansion.
729 if (!is_maximal_no_gc()) {
730 result = expand_heap_and_allocate(size, is_tlab);
731 }
732 return result; // Could be null if we are out of space.
733 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
734 // Do an incremental collection.
735 do_collection(false, // full
736 false, // clear_all_soft_refs
737 size, // size
738 is_tlab, // is_tlab
739 GenCollectedHeap::OldGen); // max_generation
740 } else {
741 log_trace(gc)(" :: Trying full because partial may fail :: ");
742 // Try a full collection; see delta for bug id 6266275
743 // for the original code and why this has been simplified
744 // with from-space allocation criteria modified and
745 // such allocation moved out of the safepoint path.
746 do_collection(true, // full
747 false, // clear_all_soft_refs
748 size, // size
749 is_tlab, // is_tlab
750 GenCollectedHeap::OldGen); // max_generation
751 }
752
753 result = attempt_allocation(size, is_tlab, false /*first_only*/);
754
755 if (result != NULL) {
756 assert(is_in_reserved(result), "result not in heap");
757 return result;
758 }
759
760 // OK, collection failed, try expansion.
761 result = expand_heap_and_allocate(size, is_tlab);
762 if (result != NULL) {
763 return result;
764 }
765
766 // If we reach this point, we're really out of memory. Try every trick
767 // we can to reclaim memory. Force collection of soft references. Force
768 // a complete compaction of the heap. Any additional methods for finding
769 // free memory should be here, especially if they are expensive. If this
770 // attempt fails, an OOM exception will be thrown.
771 {
772 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
773
774 do_collection(true, // full
775 true, // clear_all_soft_refs
776 size, // size
777 is_tlab, // is_tlab
778 GenCollectedHeap::OldGen); // max_generation
779 }
780
781 result = attempt_allocation(size, is_tlab, false /* first_only */);
782 if (result != NULL) {
783 assert(is_in_reserved(result), "result not in heap");
784 return result;
785 }
786
787 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
788 "Flag should have been handled and cleared prior to this point");
789
790 // What else? We might try synchronous finalization later. If the total
791 // space available is large enough for the allocation, then a more
792 // complete compaction phase than we've tried so far might be
793 // appropriate.
794 return NULL;
795 }
796
797 #ifdef ASSERT
798 class AssertNonScavengableClosure: public OopClosure {
799 public:
800 virtual void do_oop(oop* p) {
801 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
802 "Referent should not be scavengable."); }
803 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
804 };
805 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
806 #endif
807
808 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
809 ScanningOption so,
810 OopClosure* strong_roots,
811 CLDClosure* strong_cld_closure,
812 CLDClosure* weak_cld_closure,
813 CodeBlobToOopClosure* code_roots) {
814 // General roots.
815 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
816 assert(code_roots != NULL, "code root closure should always be set");
817 // _n_termination for _process_strong_tasks should be set up stream
818 // in a method not running in a GC worker. Otherwise the GC worker
819 // could be trying to change the termination condition while the task
820 // is executing in another GC worker.
821
822 if (_process_strong_tasks->try_claim_task(GCH_PS_ClassLoaderDataGraph_oops_do)) {
823 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
824 }
825
826 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
827 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
828
829 bool is_par = scope->n_threads() > 1;
830 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
831
832 if (_process_strong_tasks->try_claim_task(GCH_PS_Universe_oops_do)) {
833 Universe::oops_do(strong_roots);
834 }
835 // Global (strong) JNI handles
836 if (_process_strong_tasks->try_claim_task(GCH_PS_JNIHandles_oops_do)) {
837 JNIHandles::oops_do(strong_roots);
838 }
839
840 if (_process_strong_tasks->try_claim_task(GCH_PS_ObjectSynchronizer_oops_do)) {
841 ObjectSynchronizer::oops_do(strong_roots);
842 }
843 if (_process_strong_tasks->try_claim_task(GCH_PS_Management_oops_do)) {
844 Management::oops_do(strong_roots);
845 }
846 if (_process_strong_tasks->try_claim_task(GCH_PS_jvmti_oops_do)) {
847 JvmtiExport::oops_do(strong_roots);
848 }
849 if (UseAOT && _process_strong_tasks->try_claim_task(GCH_PS_aot_oops_do)) {
850 AOTLoader::oops_do(strong_roots);
851 }
852
853 if (_process_strong_tasks->try_claim_task(GCH_PS_SystemDictionary_oops_do)) {
854 SystemDictionary::oops_do(strong_roots);
855 }
856
857 if (_process_strong_tasks->try_claim_task(GCH_PS_CodeCache_oops_do)) {
858 if (so & SO_ScavengeCodeCache) {
859 assert(code_roots != NULL, "must supply closure for code cache");
860
861 // We only visit parts of the CodeCache when scavenging.
862 ScavengableNMethods::scavengable_nmethods_do(code_roots);
863 }
864 if (so & SO_AllCodeCache) {
865 assert(code_roots != NULL, "must supply closure for code cache");
866
867 // CMSCollector uses this to do intermediate-strength collections.
868 // We scan the entire code cache, since CodeCache::do_unloading is not called.
869 CodeCache::blobs_do(code_roots);
870 }
871 // Verify that the code cache contents are not subject to
872 // movement by a scavenging collection.
873 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
874 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
875 }
876 }
877
878 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
879 OopsInGenClosure* root_closure,
880 OopsInGenClosure* old_gen_closure,
881 CLDClosure* cld_closure) {
882 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
883
884 process_roots(scope, SO_ScavengeCodeCache, root_closure,
885 cld_closure, cld_closure, &mark_code_closure);
886
887 if (_process_strong_tasks->try_claim_task(GCH_PS_younger_gens)) {
888 root_closure->reset_generation();
889 }
890
891 // When collection is parallel, all threads get to cooperate to do
892 // old generation scanning.
893 old_gen_closure->set_generation(_old_gen);
894 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
895 old_gen_closure->reset_generation();
896
897 _process_strong_tasks->all_tasks_completed(scope->n_threads());
898 }
899
900 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
901 bool is_adjust_phase,
902 ScanningOption so,
903 bool only_strong_roots,
904 OopsInGenClosure* root_closure,
905 CLDClosure* cld_closure) {
906 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
907 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
908
909 process_roots(scope, so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
910 _process_strong_tasks->all_tasks_completed(scope->n_threads());
911 }
912
913 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
914 WeakProcessor::oops_do(root_closure);
915 _young_gen->ref_processor()->weak_oops_do(root_closure);
916 _old_gen->ref_processor()->weak_oops_do(root_closure);
917 }
918
919 bool GenCollectedHeap::no_allocs_since_save_marks() {
920 return _young_gen->no_allocs_since_save_marks() &&
921 _old_gen->no_allocs_since_save_marks();
922 }
923
924 bool GenCollectedHeap::supports_inline_contig_alloc() const {
925 return _young_gen->supports_inline_contig_alloc();
926 }
927
928 HeapWord* volatile* GenCollectedHeap::top_addr() const {
929 return _young_gen->top_addr();
930 }
931
932 HeapWord** GenCollectedHeap::end_addr() const {
933 return _young_gen->end_addr();
934 }
935
936 // public collection interfaces
937
938 void GenCollectedHeap::collect(GCCause::Cause cause) {
939 if (cause == GCCause::_wb_young_gc) {
940 // Young collection for the WhiteBox API.
941 collect(cause, YoungGen);
942 } else {
943 #ifdef ASSERT
944 if (cause == GCCause::_scavenge_alot) {
945 // Young collection only.
946 collect(cause, YoungGen);
947 } else {
948 // Stop-the-world full collection.
949 collect(cause, OldGen);
950 }
951 #else
952 // Stop-the-world full collection.
953 collect(cause, OldGen);
954 #endif
955 }
956 }
957
958 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
959 // The caller doesn't have the Heap_lock
960 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
961 MutexLocker ml(Heap_lock);
962 collect_locked(cause, max_generation);
963 }
964
965 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
966 // The caller has the Heap_lock
967 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
968 collect_locked(cause, OldGen);
969 }
970
971 // this is the private collection interface
972 // The Heap_lock is expected to be held on entry.
973
974 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
975 // Read the GC count while holding the Heap_lock
976 unsigned int gc_count_before = total_collections();
977 unsigned int full_gc_count_before = total_full_collections();
978 {
979 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
980 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
981 cause, max_generation);
982 VMThread::execute(&op);
983 }
984 }
985
986 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
987 do_full_collection(clear_all_soft_refs, OldGen);
988 }
989
990 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
991 GenerationType last_generation) {
992 GenerationType local_last_generation;
993 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
994 gc_cause() == GCCause::_gc_locker) {
995 local_last_generation = YoungGen;
996 } else {
997 local_last_generation = last_generation;
998 }
999
1000 do_collection(true, // full
1001 clear_all_soft_refs, // clear_all_soft_refs
1002 0, // size
1003 false, // is_tlab
1004 local_last_generation); // last_generation
1005 // Hack XXX FIX ME !!!
1006 // A scavenge may not have been attempted, or may have
1007 // been attempted and failed, because the old gen was too full
1008 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1009 incremental_collection_will_fail(false /* don't consult_young */)) {
1010 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1011 // This time allow the old gen to be collected as well
1012 do_collection(true, // full
1013 clear_all_soft_refs, // clear_all_soft_refs
1014 0, // size
1015 false, // is_tlab
1016 OldGen); // last_generation
1017 }
1018 }
1019
1020 bool GenCollectedHeap::is_in_young(oop p) {
1021 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1022 assert(result == _young_gen->is_in_reserved(p),
1023 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1024 return result;
1025 }
1026
1027 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1028 bool GenCollectedHeap::is_in(const void* p) const {
1029 return _young_gen->is_in(p) || _old_gen->is_in(p);
1030 }
1031
1032 #ifdef ASSERT
1033 // Don't implement this by using is_in_young(). This method is used
1034 // in some cases to check that is_in_young() is correct.
1035 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1036 assert(is_in_reserved(p) || p == NULL,
1037 "Does not work if address is non-null and outside of the heap");
1038 return p < _young_gen->reserved().end() && p != NULL;
1039 }
1040 #endif
1041
1042 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
1043 _young_gen->oop_iterate(cl);
1044 _old_gen->oop_iterate(cl);
1045 }
1046
1047 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1048 _young_gen->object_iterate(cl);
1049 _old_gen->object_iterate(cl);
1050 }
1051
1052 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1053 _young_gen->safe_object_iterate(cl);
1054 _old_gen->safe_object_iterate(cl);
1055 }
1056
1057 Space* GenCollectedHeap::space_containing(const void* addr) const {
1058 Space* res = _young_gen->space_containing(addr);
1059 if (res != NULL) {
1060 return res;
1061 }
1062 res = _old_gen->space_containing(addr);
1063 assert(res != NULL, "Could not find containing space");
1064 return res;
1065 }
1066
1067 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1068 assert(is_in_reserved(addr), "block_start of address outside of heap");
1069 if (_young_gen->is_in_reserved(addr)) {
1070 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1071 return _young_gen->block_start(addr);
1072 }
1073
1074 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1075 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1076 return _old_gen->block_start(addr);
1077 }
1078
1079 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1080 assert(is_in_reserved(addr), "block_size of address outside of heap");
1081 if (_young_gen->is_in_reserved(addr)) {
1082 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1083 return _young_gen->block_size(addr);
1084 }
1085
1086 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1087 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1088 return _old_gen->block_size(addr);
1089 }
1090
1091 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1092 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1093 assert(block_start(addr) == addr, "addr must be a block start");
1094 if (_young_gen->is_in_reserved(addr)) {
1095 return _young_gen->block_is_obj(addr);
1096 }
1097
1098 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1099 return _old_gen->block_is_obj(addr);
1100 }
1101
1102 bool GenCollectedHeap::supports_tlab_allocation() const {
1103 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1104 return _young_gen->supports_tlab_allocation();
1105 }
1106
1107 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1108 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1109 if (_young_gen->supports_tlab_allocation()) {
1110 return _young_gen->tlab_capacity();
1111 }
1112 return 0;
1113 }
1114
1115 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1116 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1117 if (_young_gen->supports_tlab_allocation()) {
1118 return _young_gen->tlab_used();
1119 }
1120 return 0;
1121 }
1122
1123 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1124 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1125 if (_young_gen->supports_tlab_allocation()) {
1126 return _young_gen->unsafe_max_tlab_alloc();
1127 }
1128 return 0;
1129 }
1130
1131 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1132 size_t requested_size,
1133 size_t* actual_size) {
1134 bool gc_overhead_limit_was_exceeded;
1135 HeapWord* result = mem_allocate_work(requested_size /* size */,
1136 true /* is_tlab */,
1137 &gc_overhead_limit_was_exceeded);
1138 if (result != NULL) {
1139 *actual_size = requested_size;
1140 }
1141
1142 return result;
1143 }
1144
1145 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1146 // from the list headed by "*prev_ptr".
1147 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1148 bool first = true;
1149 size_t min_size = 0; // "first" makes this conceptually infinite.
1150 ScratchBlock **smallest_ptr, *smallest;
1151 ScratchBlock *cur = *prev_ptr;
1152 while (cur) {
1153 assert(*prev_ptr == cur, "just checking");
1154 if (first || cur->num_words < min_size) {
1155 smallest_ptr = prev_ptr;
1156 smallest = cur;
1157 min_size = smallest->num_words;
1158 first = false;
1159 }
1160 prev_ptr = &cur->next;
1161 cur = cur->next;
1162 }
1163 smallest = *smallest_ptr;
1164 *smallest_ptr = smallest->next;
1165 return smallest;
1166 }
1167
1168 // Sort the scratch block list headed by res into decreasing size order,
1169 // and set "res" to the result.
1170 static void sort_scratch_list(ScratchBlock*& list) {
1171 ScratchBlock* sorted = NULL;
1172 ScratchBlock* unsorted = list;
1173 while (unsorted) {
1174 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1175 smallest->next = sorted;
1176 sorted = smallest;
1177 }
1178 list = sorted;
1179 }
1180
1181 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1182 size_t max_alloc_words) {
1183 ScratchBlock* res = NULL;
1184 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1185 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1186 sort_scratch_list(res);
1187 return res;
1188 }
1189
1190 void GenCollectedHeap::release_scratch() {
1191 _young_gen->reset_scratch();
1192 _old_gen->reset_scratch();
1193 }
1194
1195 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1196 void do_generation(Generation* gen) {
1197 gen->prepare_for_verify();
1198 }
1199 };
1200
1201 void GenCollectedHeap::prepare_for_verify() {
1202 ensure_parsability(false); // no need to retire TLABs
1203 GenPrepareForVerifyClosure blk;
1204 generation_iterate(&blk, false);
1205 }
1206
1207 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1208 bool old_to_young) {
1209 if (old_to_young) {
1210 cl->do_generation(_old_gen);
1211 cl->do_generation(_young_gen);
1212 } else {
1213 cl->do_generation(_young_gen);
1214 cl->do_generation(_old_gen);
1215 }
1216 }
1217
1218 bool GenCollectedHeap::is_maximal_no_gc() const {
1219 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1220 }
1221
1222 void GenCollectedHeap::save_marks() {
1223 _young_gen->save_marks();
1224 _old_gen->save_marks();
1225 }
1226
1227 GenCollectedHeap* GenCollectedHeap::heap() {
1228 CollectedHeap* heap = Universe::heap();
1229 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1230 assert(heap->kind() == CollectedHeap::Serial ||
1231 heap->kind() == CollectedHeap::CMS, "Invalid name");
1232 return (GenCollectedHeap*) heap;
1233 }
1234
1235 #if INCLUDE_SERIALGC
1236 void GenCollectedHeap::prepare_for_compaction() {
1237 // Start by compacting into same gen.
1238 CompactPoint cp(_old_gen);
1239 _old_gen->prepare_for_compaction(&cp);
1240 _young_gen->prepare_for_compaction(&cp);
1241 }
1242 #endif // INCLUDE_SERIALGC
1243
1244 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1245 log_debug(gc, verify)("%s", _old_gen->name());
1246 _old_gen->verify();
1247
1248 log_debug(gc, verify)("%s", _old_gen->name());
1249 _young_gen->verify();
1250
1251 log_debug(gc, verify)("RemSet");
1252 rem_set()->verify();
1253 }
1254
1255 void GenCollectedHeap::print_on(outputStream* st) const {
1256 _young_gen->print_on(st);
1257 _old_gen->print_on(st);
1258 MetaspaceUtils::print_on(st);
1259 }
1260
1261 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1262 }
1263
1264 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1265 }
1266
1267 void GenCollectedHeap::print_tracing_info() const {
1268 if (log_is_enabled(Debug, gc, heap, exit)) {
1269 LogStreamHandle(Debug, gc, heap, exit) lsh;
1270 _young_gen->print_summary_info_on(&lsh);
1271 _old_gen->print_summary_info_on(&lsh);
1272 }
1273 }
1274
1275 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1276 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1277 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1278 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1279 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1280 }
1281
1282 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1283 private:
1284 bool _full;
1285 public:
1286 void do_generation(Generation* gen) {
1287 gen->gc_prologue(_full);
1288 }
1289 GenGCPrologueClosure(bool full) : _full(full) {};
1290 };
1291
1292 void GenCollectedHeap::gc_prologue(bool full) {
1293 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1294
1295 // Fill TLAB's and such
1296 ensure_parsability(true); // retire TLABs
1297
1298 // Walk generations
1299 GenGCPrologueClosure blk(full);
1300 generation_iterate(&blk, false); // not old-to-young.
1301 };
1302
1303 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1304 private:
1305 bool _full;
1306 public:
1307 void do_generation(Generation* gen) {
1308 gen->gc_epilogue(_full);
1309 }
1310 GenGCEpilogueClosure(bool full) : _full(full) {};
1311 };
1312
1313 void GenCollectedHeap::gc_epilogue(bool full) {
1314 #if COMPILER2_OR_JVMCI
1315 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1316 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1317 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1318 #endif // COMPILER2_OR_JVMCI
1319
1320 resize_all_tlabs();
1321
1322 GenGCEpilogueClosure blk(full);
1323 generation_iterate(&blk, false); // not old-to-young.
1324
1325 if (!CleanChunkPoolAsync) {
1326 Chunk::clean_chunk_pool();
1327 }
1328
1329 MetaspaceCounters::update_performance_counters();
1330 CompressedClassSpaceCounters::update_performance_counters();
1331 };
1332
1333 #ifndef PRODUCT
1334 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1335 private:
1336 public:
1337 void do_generation(Generation* gen) {
1338 gen->record_spaces_top();
1339 }
1340 };
1341
1342 void GenCollectedHeap::record_gen_tops_before_GC() {
1343 if (ZapUnusedHeapArea) {
1344 GenGCSaveTopsBeforeGCClosure blk;
1345 generation_iterate(&blk, false); // not old-to-young.
1346 }
1347 }
1348 #endif // not PRODUCT
1349
1350 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1351 public:
1352 void do_generation(Generation* gen) {
1353 gen->ensure_parsability();
1354 }
1355 };
1356
1357 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1358 CollectedHeap::ensure_parsability(retire_tlabs);
1359 GenEnsureParsabilityClosure ep_cl;
1360 generation_iterate(&ep_cl, false);
1361 }
1362
1363 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1364 oop obj,
1365 size_t obj_size) {
1366 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1367 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1368 HeapWord* result = NULL;
1369
1370 result = old_gen->expand_and_allocate(obj_size, false);
1371
1372 if (result != NULL) {
1373 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1374 }
1375 return oop(result);
1376 }
1377
1378 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1379 jlong _time; // in ms
1380 jlong _now; // in ms
1381
1382 public:
1383 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1384
1385 jlong time() { return _time; }
1386
1387 void do_generation(Generation* gen) {
1388 _time = MIN2(_time, gen->time_of_last_gc(_now));
1389 }
1390 };
1391
1392 jlong GenCollectedHeap::millis_since_last_gc() {
1393 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1394 // provided the underlying platform provides such a time source
1395 // (and it is bug free). So we still have to guard against getting
1396 // back a time later than 'now'.
1397 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1398 GenTimeOfLastGCClosure tolgc_cl(now);
1399 // iterate over generations getting the oldest
1400 // time that a generation was collected
1401 generation_iterate(&tolgc_cl, false);
1402
1403 jlong retVal = now - tolgc_cl.time();
1404 if (retVal < 0) {
1405 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1406 ". returning zero instead.", retVal);
1407 return 0;
1408 }
1409 return retVal;
1410 }