1 /*
2 * Copyright (c) 2000, 2018, 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/space.hpp"
51 #include "gc/shared/strongRootsScope.hpp"
52 #include "gc/shared/weakProcessor.hpp"
53 #include "gc/shared/workgroup.hpp"
54 #include "memory/filemap.hpp"
55 #include "memory/metaspaceCounters.hpp"
56 #include "memory/resourceArea.hpp"
57 #include "oops/oop.inline.hpp"
58 #include "runtime/biasedLocking.hpp"
59 #include "runtime/flags/flagSetting.hpp"
60 #include "runtime/handles.hpp"
61 #include "runtime/handles.inline.hpp"
62 #include "runtime/java.hpp"
63 #include "runtime/vmThread.hpp"
64 #include "services/management.hpp"
65 #include "services/memoryService.hpp"
66 #include "utilities/debug.hpp"
67 #include "utilities/formatBuffer.hpp"
68 #include "utilities/macros.hpp"
69 #include "utilities/stack.inline.hpp"
70 #include "utilities/vmError.hpp"
71
72 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy,
73 Generation::Name young,
74 Generation::Name old,
75 const char* policy_counters_name) :
76 CollectedHeap(),
77 _young_gen_spec(new GenerationSpec(young,
78 policy->initial_young_size(),
79 policy->max_young_size(),
80 policy->gen_alignment())),
81 _old_gen_spec(new GenerationSpec(old,
82 policy->initial_old_size(),
83 policy->max_old_size(),
84 policy->gen_alignment())),
85 _rem_set(NULL),
86 _gen_policy(policy),
87 _soft_ref_gen_policy(),
88 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
89 _full_collections_completed(0),
90 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)) {
91 }
92
93 jint GenCollectedHeap::initialize() {
94 // While there are no constraints in the GC code that HeapWordSize
95 // be any particular value, there are multiple other areas in the
96 // system which believe this to be true (e.g. oop->object_size in some
97 // cases incorrectly returns the size in wordSize units rather than
98 // HeapWordSize).
99 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
100
101 // Allocate space for the heap.
102
103 char* heap_address;
104 ReservedSpace heap_rs;
105
106 size_t heap_alignment = collector_policy()->heap_alignment();
107
108 heap_address = allocate(heap_alignment, &heap_rs);
109
110 if (!heap_rs.is_reserved()) {
111 vm_shutdown_during_initialization(
112 "Could not reserve enough space for object heap");
113 return JNI_ENOMEM;
114 }
115
116 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
117
118 _rem_set = create_rem_set(reserved_region());
119 _rem_set->initialize();
120 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
121 bs->initialize();
122 BarrierSet::set_barrier_set(bs);
123
124 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false);
125 _young_gen = _young_gen_spec->init(young_rs, rem_set());
126 heap_rs = heap_rs.last_part(_young_gen_spec->max_size());
127
128 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false);
129 _old_gen = _old_gen_spec->init(old_rs, rem_set());
130 clear_incremental_collection_failed();
131
132 return JNI_OK;
133 }
134
135 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
136 return new CardTableRS(reserved_region, false /* scan_concurrently */);
137 }
138
139 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
140 size_t init_promo_size,
141 size_t init_survivor_size) {
142 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
143 _size_policy = new AdaptiveSizePolicy(init_eden_size,
144 init_promo_size,
145 init_survivor_size,
146 max_gc_pause_sec,
147 GCTimeRatio);
148 }
149
150 char* GenCollectedHeap::allocate(size_t alignment,
151 ReservedSpace* heap_rs){
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 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
167
168 os::trace_page_sizes("Heap",
169 collector_policy()->min_heap_byte_size(),
170 total_reserved,
171 alignment,
172 heap_rs->base(),
173 heap_rs->size());
174
175 return heap_rs->base();
176 }
177
178 void GenCollectedHeap::post_initialize() {
179 CollectedHeap::post_initialize();
180 ref_processing_init();
181
182 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
183
184 initialize_size_policy(def_new_gen->eden()->capacity(),
185 _old_gen->capacity(),
186 def_new_gen->from()->capacity());
187
188 MarkSweep::initialize();
189 }
190
191 void GenCollectedHeap::ref_processing_init() {
192 _young_gen->ref_processor_init();
193 _old_gen->ref_processor_init();
194 }
195
196 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
197 return _young_gen_spec;
198 }
199
200 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
201 return _old_gen_spec;
202 }
203
204 size_t GenCollectedHeap::capacity() const {
205 return _young_gen->capacity() + _old_gen->capacity();
206 }
207
208 size_t GenCollectedHeap::used() const {
209 return _young_gen->used() + _old_gen->used();
210 }
211
212 void GenCollectedHeap::save_used_regions() {
213 _old_gen->save_used_region();
214 _young_gen->save_used_region();
215 }
216
217 size_t GenCollectedHeap::max_capacity() const {
218 return _young_gen->max_capacity() + _old_gen->max_capacity();
219 }
220
221 // Update the _full_collections_completed counter
222 // at the end of a stop-world full GC.
223 unsigned int GenCollectedHeap::update_full_collections_completed() {
224 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
225 assert(_full_collections_completed <= _total_full_collections,
226 "Can't complete more collections than were started");
227 _full_collections_completed = _total_full_collections;
228 ml.notify_all();
229 return _full_collections_completed;
230 }
231
232 // Update the _full_collections_completed counter, as appropriate,
233 // at the end of a concurrent GC cycle. Note the conditional update
234 // below to allow this method to be called by a concurrent collector
235 // without synchronizing in any manner with the VM thread (which
236 // may already have initiated a STW full collection "concurrently").
237 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
238 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
239 assert((_full_collections_completed <= _total_full_collections) &&
240 (count <= _total_full_collections),
241 "Can't complete more collections than were started");
242 if (count > _full_collections_completed) {
243 _full_collections_completed = count;
244 ml.notify_all();
245 }
246 return _full_collections_completed;
247 }
248
249 // Return true if any of the following is true:
250 // . the allocation won't fit into the current young gen heap
251 // . gc locker is occupied (jni critical section)
252 // . heap memory is tight -- the most recent previous collection
253 // was a full collection because a partial collection (would
254 // have) failed and is likely to fail again
255 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
256 size_t young_capacity = _young_gen->capacity_before_gc();
257 return (word_size > heap_word_size(young_capacity))
258 || GCLocker::is_active_and_needs_gc()
259 || incremental_collection_failed();
260 }
261
262 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
263 HeapWord* result = NULL;
264 if (_old_gen->should_allocate(size, is_tlab)) {
265 result = _old_gen->expand_and_allocate(size, is_tlab);
266 }
267 if (result == NULL) {
268 if (_young_gen->should_allocate(size, is_tlab)) {
269 result = _young_gen->expand_and_allocate(size, is_tlab);
270 }
271 }
272 assert(result == NULL || is_in_reserved(result), "result not in heap");
273 return result;
274 }
275
276 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
277 bool is_tlab,
278 bool* gc_overhead_limit_was_exceeded) {
279 // In general gc_overhead_limit_was_exceeded should be false so
280 // set it so here and reset it to true only if the gc time
281 // limit is being exceeded as checked below.
282 *gc_overhead_limit_was_exceeded = false;
283
284 HeapWord* result = NULL;
285
286 // Loop until the allocation is satisfied, or unsatisfied after GC.
287 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
288 HandleMark hm; // Discard any handles allocated in each iteration.
289
290 // First allocation attempt is lock-free.
291 Generation *young = _young_gen;
292 assert(young->supports_inline_contig_alloc(),
293 "Otherwise, must do alloc within heap lock");
294 if (young->should_allocate(size, is_tlab)) {
295 result = young->par_allocate(size, is_tlab);
296 if (result != NULL) {
297 assert(is_in_reserved(result), "result not in heap");
298 return result;
299 }
300 }
301 uint gc_count_before; // Read inside the Heap_lock locked region.
302 {
303 MutexLocker ml(Heap_lock);
304 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
305 // Note that only large objects get a shot at being
306 // allocated in later generations.
307 bool first_only = !should_try_older_generation_allocation(size);
308
309 result = attempt_allocation(size, is_tlab, first_only);
310 if (result != NULL) {
311 assert(is_in_reserved(result), "result not in heap");
312 return result;
313 }
314
315 if (GCLocker::is_active_and_needs_gc()) {
316 if (is_tlab) {
317 return NULL; // Caller will retry allocating individual object.
318 }
319 if (!is_maximal_no_gc()) {
320 // Try and expand heap to satisfy request.
321 result = expand_heap_and_allocate(size, is_tlab);
322 // Result could be null if we are out of space.
323 if (result != NULL) {
324 return result;
325 }
326 }
327
328 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
329 return NULL; // We didn't get to do a GC and we didn't get any memory.
330 }
331
332 // If this thread is not in a jni critical section, we stall
333 // the requestor until the critical section has cleared and
334 // GC allowed. When the critical section clears, a GC is
335 // initiated by the last thread exiting the critical section; so
336 // we retry the allocation sequence from the beginning of the loop,
337 // rather than causing more, now probably unnecessary, GC attempts.
338 JavaThread* jthr = JavaThread::current();
339 if (!jthr->in_critical()) {
340 MutexUnlocker mul(Heap_lock);
341 // Wait for JNI critical section to be exited
342 GCLocker::stall_until_clear();
343 gclocker_stalled_count += 1;
344 continue;
345 } else {
346 if (CheckJNICalls) {
347 fatal("Possible deadlock due to allocating while"
348 " in jni critical section");
349 }
350 return NULL;
351 }
352 }
353
354 // Read the gc count while the heap lock is held.
355 gc_count_before = total_collections();
356 }
357
358 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
359 VMThread::execute(&op);
360 if (op.prologue_succeeded()) {
361 result = op.result();
362 if (op.gc_locked()) {
363 assert(result == NULL, "must be NULL if gc_locked() is true");
364 continue; // Retry and/or stall as necessary.
365 }
366
367 // Allocation has failed and a collection
368 // has been done. If the gc time limit was exceeded the
369 // this time, return NULL so that an out-of-memory
370 // will be thrown. Clear gc_overhead_limit_exceeded
371 // so that the overhead exceeded does not persist.
372
373 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
374 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
375
376 if (limit_exceeded && softrefs_clear) {
377 *gc_overhead_limit_was_exceeded = true;
378 size_policy()->set_gc_overhead_limit_exceeded(false);
379 if (op.result() != NULL) {
380 CollectedHeap::fill_with_object(op.result(), size);
381 }
382 return NULL;
383 }
384 assert(result == NULL || is_in_reserved(result),
385 "result not in heap");
386 return result;
387 }
388
389 // Give a warning if we seem to be looping forever.
390 if ((QueuedAllocationWarningCount > 0) &&
391 (try_count % QueuedAllocationWarningCount == 0)) {
392 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
393 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
394 }
395 }
396 }
397
398 #ifndef PRODUCT
399 // Override of memory state checking method in CollectedHeap:
400 // Some collectors (CMS for example) can't have badHeapWordVal written
401 // in the first two words of an object. (For instance , in the case of
402 // CMS these words hold state used to synchronize between certain
403 // (concurrent) GC steps and direct allocating mutators.)
404 // The skip_header_HeapWords() method below, allows us to skip
405 // over the requisite number of HeapWord's. Note that (for
406 // generational collectors) this means that those many words are
407 // skipped in each object, irrespective of the generation in which
408 // that object lives. The resultant loss of precision seems to be
409 // harmless and the pain of avoiding that imprecision appears somewhat
410 // higher than we are prepared to pay for such rudimentary debugging
411 // support.
412 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
413 size_t size) {
414 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
415 // We are asked to check a size in HeapWords,
416 // but the memory is mangled in juint words.
417 juint* start = (juint*) (addr + skip_header_HeapWords());
418 juint* end = (juint*) (addr + size);
419 for (juint* slot = start; slot < end; slot += 1) {
420 assert(*slot == badHeapWordVal,
421 "Found non badHeapWordValue in pre-allocation check");
422 }
423 }
424 }
425 #endif
426
427 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
428 bool is_tlab,
429 bool first_only) {
430 HeapWord* res = NULL;
431
432 if (_young_gen->should_allocate(size, is_tlab)) {
433 res = _young_gen->allocate(size, is_tlab);
434 if (res != NULL || first_only) {
435 return res;
436 }
437 }
438
439 if (_old_gen->should_allocate(size, is_tlab)) {
440 res = _old_gen->allocate(size, is_tlab);
441 }
442
443 return res;
444 }
445
446 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
447 bool* gc_overhead_limit_was_exceeded) {
448 return mem_allocate_work(size,
449 false /* is_tlab */,
450 gc_overhead_limit_was_exceeded);
451 }
452
453 bool GenCollectedHeap::must_clear_all_soft_refs() {
454 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
455 _gc_cause == GCCause::_wb_full_gc;
456 }
457
458 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
459 bool is_tlab, bool run_verification, bool clear_soft_refs,
460 bool restore_marks_for_biased_locking) {
461 FormatBuffer<> title("Collect gen: %s", gen->short_name());
462 GCTraceTime(Trace, gc, phases) t1(title);
463 TraceCollectorStats tcs(gen->counters());
464 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
465
466 gen->stat_record()->invocations++;
467 gen->stat_record()->accumulated_time.start();
468
469 // Must be done anew before each collection because
470 // a previous collection will do mangling and will
471 // change top of some spaces.
472 record_gen_tops_before_GC();
473
474 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
475
476 if (run_verification && VerifyBeforeGC) {
477 HandleMark hm; // Discard invalid handles created during verification
478 Universe::verify("Before GC");
479 }
480 COMPILER2_PRESENT(DerivedPointerTable::clear());
481
482 if (restore_marks_for_biased_locking) {
483 // We perform this mark word preservation work lazily
484 // because it's only at this point that we know whether we
485 // absolutely have to do it; we want to avoid doing it for
486 // scavenge-only collections where it's unnecessary
487 BiasedLocking::preserve_marks();
488 }
489
490 // Do collection work
491 {
492 // Note on ref discovery: For what appear to be historical reasons,
493 // GCH enables and disabled (by enqueing) refs discovery.
494 // In the future this should be moved into the generation's
495 // collect method so that ref discovery and enqueueing concerns
496 // are local to a generation. The collect method could return
497 // an appropriate indication in the case that notification on
498 // the ref lock was needed. This will make the treatment of
499 // weak refs more uniform (and indeed remove such concerns
500 // from GCH). XXX
501
502 HandleMark hm; // Discard invalid handles created during gc
503 save_marks(); // save marks for all gens
504 // We want to discover references, but not process them yet.
505 // This mode is disabled in process_discovered_references if the
506 // generation does some collection work, or in
507 // enqueue_discovered_references if the generation returns
508 // without doing any work.
509 ReferenceProcessor* rp = gen->ref_processor();
510 // If the discovery of ("weak") refs in this generation is
511 // atomic wrt other collectors in this configuration, we
512 // are guaranteed to have empty discovered ref lists.
513 if (rp->discovery_is_atomic()) {
514 rp->enable_discovery();
515 rp->setup_policy(clear_soft_refs);
516 } else {
517 // collect() below will enable discovery as appropriate
518 }
519 gen->collect(full, clear_soft_refs, size, is_tlab);
520 if (!rp->enqueuing_is_done()) {
521 rp->disable_discovery();
522 } else {
523 rp->set_enqueuing_is_done(false);
524 }
525 rp->verify_no_references_recorded();
526 }
527
528 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
529
530 gen->stat_record()->accumulated_time.stop();
531
532 update_gc_stats(gen, full);
533
534 if (run_verification && VerifyAfterGC) {
535 HandleMark hm; // Discard invalid handles created during verification
536 Universe::verify("After GC");
537 }
538 }
539
540 void GenCollectedHeap::do_collection(bool full,
541 bool clear_all_soft_refs,
542 size_t size,
543 bool is_tlab,
544 GenerationType max_generation) {
545 ResourceMark rm;
546 DEBUG_ONLY(Thread* my_thread = Thread::current();)
547
548 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
549 assert(my_thread->is_VM_thread() ||
550 my_thread->is_ConcurrentGC_thread(),
551 "incorrect thread type capability");
552 assert(Heap_lock->is_locked(),
553 "the requesting thread should have the Heap_lock");
554 guarantee(!is_gc_active(), "collection is not reentrant");
555
556 if (GCLocker::check_active_before_gc()) {
557 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
558 }
559
560 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
561 soft_ref_policy()->should_clear_all_soft_refs();
562
563 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
564
565 const size_t metadata_prev_used = MetaspaceUtils::used_bytes();
566
567
568 FlagSetting fl(_is_gc_active, true);
569
570 bool complete = full && (max_generation == OldGen);
571 bool old_collects_young = complete && !ScavengeBeforeFullGC;
572 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
573
574 size_t young_prev_used = _young_gen->used();
575 size_t old_prev_used = _old_gen->used();
576
577 bool run_verification = total_collections() >= VerifyGCStartAt;
578 bool prepared_for_verification = false;
579 bool do_full_collection = false;
580
581 if (do_young_collection) {
582 GCIdMark gc_id_mark;
583 GCTraceCPUTime tcpu;
584 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true);
585
586 print_heap_before_gc();
587
588 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
589 prepare_for_verify();
590 prepared_for_verification = true;
591 }
592
593 gc_prologue(complete);
594 increment_total_collections(complete);
595
596 collect_generation(_young_gen,
597 full,
598 size,
599 is_tlab,
600 run_verification && VerifyGCLevel <= 0,
601 do_clear_all_soft_refs,
602 false);
603
604 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
605 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
606 // Allocation request was met by young GC.
607 size = 0;
608 }
609
610 // Ask if young collection is enough. If so, do the final steps for young collection,
611 // and fallthrough to the end.
612 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
613 if (!do_full_collection) {
614 // Adjust generation sizes.
615 _young_gen->compute_new_size();
616
617 print_heap_change(young_prev_used, old_prev_used);
618 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
619
620 // Track memory usage and detect low memory after GC finishes
621 MemoryService::track_memory_usage();
622
623 gc_epilogue(complete);
624 }
625
626 print_heap_after_gc();
627
628 } else {
629 // No young collection, ask if we need to perform Full collection.
630 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
631 }
632
633 if (do_full_collection) {
634 GCIdMark gc_id_mark;
635 GCTraceCPUTime tcpu;
636 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
637
638 print_heap_before_gc();
639
640 if (!prepared_for_verification && run_verification &&
641 VerifyGCLevel <= 1 && VerifyBeforeGC) {
642 prepare_for_verify();
643 }
644
645 if (!do_young_collection) {
646 gc_prologue(complete);
647 increment_total_collections();
648 }
649 increment_total_full_collections();
650
651 collect_generation(_old_gen,
652 full,
653 size,
654 is_tlab,
655 run_verification && VerifyGCLevel <= 1,
656 do_clear_all_soft_refs,
657 true);
658
659 // Adjust generation sizes.
660 _old_gen->compute_new_size();
661 _young_gen->compute_new_size();
662
663 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
664 ClassLoaderDataGraph::purge();
665 MetaspaceUtils::verify_metrics();
666 // Resize the metaspace capacity after full collections
667 MetaspaceGC::compute_new_size();
668 update_full_collections_completed();
669
670 print_heap_change(young_prev_used, old_prev_used);
671 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
672
673 // Track memory usage and detect low memory after GC finishes
674 MemoryService::track_memory_usage();
675
676 gc_epilogue(complete);
677
678 BiasedLocking::restore_marks();
679
680 print_heap_after_gc();
681 }
682
683 #ifdef TRACESPINNING
684 ParallelTaskTerminator::print_termination_counts();
685 #endif
686 }
687
688 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
689 GenCollectedHeap::GenerationType max_gen) const {
690 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
691 }
692
693 void GenCollectedHeap::register_nmethod(nmethod* nm) {
694 CodeCache::register_scavenge_root_nmethod(nm);
695 }
696
697 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
698 CodeCache::verify_scavenge_root_nmethod(nm);
699 }
700
701 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
702 GCCauseSetter x(this, GCCause::_allocation_failure);
703 HeapWord* result = NULL;
704
705 assert(size != 0, "Precondition violated");
706 if (GCLocker::is_active_and_needs_gc()) {
707 // GC locker is active; instead of a collection we will attempt
708 // to expand the heap, if there's room for expansion.
709 if (!is_maximal_no_gc()) {
710 result = expand_heap_and_allocate(size, is_tlab);
711 }
712 return result; // Could be null if we are out of space.
713 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
714 // Do an incremental collection.
715 do_collection(false, // full
716 false, // clear_all_soft_refs
717 size, // size
718 is_tlab, // is_tlab
719 GenCollectedHeap::OldGen); // max_generation
720 } else {
721 log_trace(gc)(" :: Trying full because partial may fail :: ");
722 // Try a full collection; see delta for bug id 6266275
723 // for the original code and why this has been simplified
724 // with from-space allocation criteria modified and
725 // such allocation moved out of the safepoint path.
726 do_collection(true, // full
727 false, // clear_all_soft_refs
728 size, // size
729 is_tlab, // is_tlab
730 GenCollectedHeap::OldGen); // max_generation
731 }
732
733 result = attempt_allocation(size, is_tlab, false /*first_only*/);
734
735 if (result != NULL) {
736 assert(is_in_reserved(result), "result not in heap");
737 return result;
738 }
739
740 // OK, collection failed, try expansion.
741 result = expand_heap_and_allocate(size, is_tlab);
742 if (result != NULL) {
743 return result;
744 }
745
746 // If we reach this point, we're really out of memory. Try every trick
747 // we can to reclaim memory. Force collection of soft references. Force
748 // a complete compaction of the heap. Any additional methods for finding
749 // free memory should be here, especially if they are expensive. If this
750 // attempt fails, an OOM exception will be thrown.
751 {
752 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
753
754 do_collection(true, // full
755 true, // clear_all_soft_refs
756 size, // size
757 is_tlab, // is_tlab
758 GenCollectedHeap::OldGen); // max_generation
759 }
760
761 result = attempt_allocation(size, is_tlab, false /* first_only */);
762 if (result != NULL) {
763 assert(is_in_reserved(result), "result not in heap");
764 return result;
765 }
766
767 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
768 "Flag should have been handled and cleared prior to this point");
769
770 // What else? We might try synchronous finalization later. If the total
771 // space available is large enough for the allocation, then a more
772 // complete compaction phase than we've tried so far might be
773 // appropriate.
774 return NULL;
775 }
776
777 #ifdef ASSERT
778 class AssertNonScavengableClosure: public OopClosure {
779 public:
780 virtual void do_oop(oop* p) {
781 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
782 "Referent should not be scavengable."); }
783 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
784 };
785 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
786 #endif
787
788 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
789 ScanningOption so,
790 OopClosure* strong_roots,
791 CLDClosure* strong_cld_closure,
792 CLDClosure* weak_cld_closure,
793 CodeBlobToOopClosure* code_roots) {
794 // General roots.
795 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
796 assert(code_roots != NULL, "code root closure should always be set");
797 // _n_termination for _process_strong_tasks should be set up stream
798 // in a method not running in a GC worker. Otherwise the GC worker
799 // could be trying to change the termination condition while the task
800 // is executing in another GC worker.
801
802 if (_process_strong_tasks->try_claim_task(GCH_PS_ClassLoaderDataGraph_oops_do)) {
803 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
804 }
805
806 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
807 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
808
809 bool is_par = scope->n_threads() > 1;
810 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
811
812 if (_process_strong_tasks->try_claim_task(GCH_PS_Universe_oops_do)) {
813 Universe::oops_do(strong_roots);
814 }
815 // Global (strong) JNI handles
816 if (_process_strong_tasks->try_claim_task(GCH_PS_JNIHandles_oops_do)) {
817 JNIHandles::oops_do(strong_roots);
818 }
819
820 if (_process_strong_tasks->try_claim_task(GCH_PS_ObjectSynchronizer_oops_do)) {
821 ObjectSynchronizer::oops_do(strong_roots);
822 }
823 if (_process_strong_tasks->try_claim_task(GCH_PS_Management_oops_do)) {
824 Management::oops_do(strong_roots);
825 }
826 if (_process_strong_tasks->try_claim_task(GCH_PS_jvmti_oops_do)) {
827 JvmtiExport::oops_do(strong_roots);
828 }
829 if (UseAOT && _process_strong_tasks->try_claim_task(GCH_PS_aot_oops_do)) {
830 AOTLoader::oops_do(strong_roots);
831 }
832
833 if (_process_strong_tasks->try_claim_task(GCH_PS_SystemDictionary_oops_do)) {
834 SystemDictionary::oops_do(strong_roots);
835 }
836
837 if (_process_strong_tasks->try_claim_task(GCH_PS_CodeCache_oops_do)) {
838 if (so & SO_ScavengeCodeCache) {
839 assert(code_roots != NULL, "must supply closure for code cache");
840
841 // We only visit parts of the CodeCache when scavenging.
842 CodeCache::scavenge_root_nmethods_do(code_roots);
843 }
844 if (so & SO_AllCodeCache) {
845 assert(code_roots != NULL, "must supply closure for code cache");
846
847 // CMSCollector uses this to do intermediate-strength collections.
848 // We scan the entire code cache, since CodeCache::do_unloading is not called.
849 CodeCache::blobs_do(code_roots);
850 }
851 // Verify that the code cache contents are not subject to
852 // movement by a scavenging collection.
853 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
854 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
855 }
856 }
857
858 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
859 OopClosure* root_closure,
860 OopStorage::ParState<false, false>* par_state_string) {
861 assert(root_closure != NULL, "Must be set");
862 // All threads execute the following. A specific chunk of buckets
863 // from the StringTable are the individual tasks.
864
865 // Either we should be single threaded or have a ParState
866 assert((scope->n_threads() <= 1) || par_state_string != NULL, "Parallel but no ParState");
867
868 if (scope->n_threads() > 1) {
869 StringTable::possibly_parallel_oops_do(par_state_string, root_closure);
870 } else {
871 StringTable::oops_do(root_closure);
872 }
873 }
874
875 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
876 OopsInGenClosure* root_closure,
877 OopsInGenClosure* old_gen_closure,
878 CLDClosure* cld_closure,
879 OopStorage::ParState<false, false>* par_state_string) {
880 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
881
882 process_roots(scope, SO_ScavengeCodeCache, root_closure,
883 cld_closure, cld_closure, &mark_code_closure);
884 process_string_table_roots(scope, root_closure, par_state_string);
885
886 if (_process_strong_tasks->try_claim_task(GCH_PS_younger_gens)) {
887 root_closure->reset_generation();
888 }
889
890 // When collection is parallel, all threads get to cooperate to do
891 // old generation scanning.
892 old_gen_closure->set_generation(_old_gen);
893 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
894 old_gen_closure->reset_generation();
895
896 _process_strong_tasks->all_tasks_completed(scope->n_threads());
897 }
898
899 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
900 bool is_adjust_phase,
901 ScanningOption so,
902 bool only_strong_roots,
903 OopsInGenClosure* root_closure,
904 CLDClosure* cld_closure,
905 OopStorage::ParState<false, false>* par_state_string) {
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 if (is_adjust_phase) {
911 // We never treat the string table as roots during marking
912 // for the full gc, so we only need to process it during
913 // the adjust phase.
914 process_string_table_roots(scope, root_closure, par_state_string);
915 }
916
917 _process_strong_tasks->all_tasks_completed(scope->n_threads());
918 }
919
920 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
921 WeakProcessor::oops_do(root_closure);
922 _young_gen->ref_processor()->weak_oops_do(root_closure);
923 _old_gen->ref_processor()->weak_oops_do(root_closure);
924 }
925
926 bool GenCollectedHeap::no_allocs_since_save_marks() {
927 return _young_gen->no_allocs_since_save_marks() &&
928 _old_gen->no_allocs_since_save_marks();
929 }
930
931 bool GenCollectedHeap::supports_inline_contig_alloc() const {
932 return _young_gen->supports_inline_contig_alloc();
933 }
934
935 HeapWord* volatile* GenCollectedHeap::top_addr() const {
936 return _young_gen->top_addr();
937 }
938
939 HeapWord** GenCollectedHeap::end_addr() const {
940 return _young_gen->end_addr();
941 }
942
943 // public collection interfaces
944
945 void GenCollectedHeap::collect(GCCause::Cause cause) {
946 if (cause == GCCause::_wb_young_gc) {
947 // Young collection for the WhiteBox API.
948 collect(cause, YoungGen);
949 } else {
950 #ifdef ASSERT
951 if (cause == GCCause::_scavenge_alot) {
952 // Young collection only.
953 collect(cause, YoungGen);
954 } else {
955 // Stop-the-world full collection.
956 collect(cause, OldGen);
957 }
958 #else
959 // Stop-the-world full collection.
960 collect(cause, OldGen);
961 #endif
962 }
963 }
964
965 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
966 // The caller doesn't have the Heap_lock
967 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
968 MutexLocker ml(Heap_lock);
969 collect_locked(cause, max_generation);
970 }
971
972 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
973 // The caller has the Heap_lock
974 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
975 collect_locked(cause, OldGen);
976 }
977
978 // this is the private collection interface
979 // The Heap_lock is expected to be held on entry.
980
981 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
982 // Read the GC count while holding the Heap_lock
983 unsigned int gc_count_before = total_collections();
984 unsigned int full_gc_count_before = total_full_collections();
985 {
986 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
987 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
988 cause, max_generation);
989 VMThread::execute(&op);
990 }
991 }
992
993 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
994 do_full_collection(clear_all_soft_refs, OldGen);
995 }
996
997 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
998 GenerationType last_generation) {
999 GenerationType local_last_generation;
1000 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
1001 gc_cause() == GCCause::_gc_locker) {
1002 local_last_generation = YoungGen;
1003 } else {
1004 local_last_generation = last_generation;
1005 }
1006
1007 do_collection(true, // full
1008 clear_all_soft_refs, // clear_all_soft_refs
1009 0, // size
1010 false, // is_tlab
1011 local_last_generation); // last_generation
1012 // Hack XXX FIX ME !!!
1013 // A scavenge may not have been attempted, or may have
1014 // been attempted and failed, because the old gen was too full
1015 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1016 incremental_collection_will_fail(false /* don't consult_young */)) {
1017 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1018 // This time allow the old gen to be collected as well
1019 do_collection(true, // full
1020 clear_all_soft_refs, // clear_all_soft_refs
1021 0, // size
1022 false, // is_tlab
1023 OldGen); // last_generation
1024 }
1025 }
1026
1027 bool GenCollectedHeap::is_in_young(oop p) {
1028 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1029 assert(result == _young_gen->is_in_reserved(p),
1030 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1031 return result;
1032 }
1033
1034 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1035 bool GenCollectedHeap::is_in(const void* p) const {
1036 return _young_gen->is_in(p) || _old_gen->is_in(p);
1037 }
1038
1039 #ifdef ASSERT
1040 // Don't implement this by using is_in_young(). This method is used
1041 // in some cases to check that is_in_young() is correct.
1042 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1043 assert(is_in_reserved(p) || p == NULL,
1044 "Does not work if address is non-null and outside of the heap");
1045 return p < _young_gen->reserved().end() && p != NULL;
1046 }
1047 #endif
1048
1049 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
1050 _young_gen->oop_iterate(cl);
1051 _old_gen->oop_iterate(cl);
1052 }
1053
1054 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1055 _young_gen->object_iterate(cl);
1056 _old_gen->object_iterate(cl);
1057 }
1058
1059 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1060 _young_gen->safe_object_iterate(cl);
1061 _old_gen->safe_object_iterate(cl);
1062 }
1063
1064 Space* GenCollectedHeap::space_containing(const void* addr) const {
1065 Space* res = _young_gen->space_containing(addr);
1066 if (res != NULL) {
1067 return res;
1068 }
1069 res = _old_gen->space_containing(addr);
1070 assert(res != NULL, "Could not find containing space");
1071 return res;
1072 }
1073
1074 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1075 assert(is_in_reserved(addr), "block_start of address outside of heap");
1076 if (_young_gen->is_in_reserved(addr)) {
1077 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1078 return _young_gen->block_start(addr);
1079 }
1080
1081 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1082 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1083 return _old_gen->block_start(addr);
1084 }
1085
1086 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1087 assert(is_in_reserved(addr), "block_size of address outside of heap");
1088 if (_young_gen->is_in_reserved(addr)) {
1089 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1090 return _young_gen->block_size(addr);
1091 }
1092
1093 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1094 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1095 return _old_gen->block_size(addr);
1096 }
1097
1098 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1099 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1100 assert(block_start(addr) == addr, "addr must be a block start");
1101 if (_young_gen->is_in_reserved(addr)) {
1102 return _young_gen->block_is_obj(addr);
1103 }
1104
1105 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1106 return _old_gen->block_is_obj(addr);
1107 }
1108
1109 bool GenCollectedHeap::supports_tlab_allocation() const {
1110 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1111 return _young_gen->supports_tlab_allocation();
1112 }
1113
1114 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1115 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1116 if (_young_gen->supports_tlab_allocation()) {
1117 return _young_gen->tlab_capacity();
1118 }
1119 return 0;
1120 }
1121
1122 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1123 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1124 if (_young_gen->supports_tlab_allocation()) {
1125 return _young_gen->tlab_used();
1126 }
1127 return 0;
1128 }
1129
1130 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1131 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1132 if (_young_gen->supports_tlab_allocation()) {
1133 return _young_gen->unsafe_max_tlab_alloc();
1134 }
1135 return 0;
1136 }
1137
1138 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1139 size_t requested_size,
1140 size_t* actual_size) {
1141 bool gc_overhead_limit_was_exceeded;
1142 HeapWord* result = mem_allocate_work(requested_size /* size */,
1143 true /* is_tlab */,
1144 &gc_overhead_limit_was_exceeded);
1145 if (result != NULL) {
1146 *actual_size = requested_size;
1147 }
1148
1149 return result;
1150 }
1151
1152 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1153 // from the list headed by "*prev_ptr".
1154 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1155 bool first = true;
1156 size_t min_size = 0; // "first" makes this conceptually infinite.
1157 ScratchBlock **smallest_ptr, *smallest;
1158 ScratchBlock *cur = *prev_ptr;
1159 while (cur) {
1160 assert(*prev_ptr == cur, "just checking");
1161 if (first || cur->num_words < min_size) {
1162 smallest_ptr = prev_ptr;
1163 smallest = cur;
1164 min_size = smallest->num_words;
1165 first = false;
1166 }
1167 prev_ptr = &cur->next;
1168 cur = cur->next;
1169 }
1170 smallest = *smallest_ptr;
1171 *smallest_ptr = smallest->next;
1172 return smallest;
1173 }
1174
1175 // Sort the scratch block list headed by res into decreasing size order,
1176 // and set "res" to the result.
1177 static void sort_scratch_list(ScratchBlock*& list) {
1178 ScratchBlock* sorted = NULL;
1179 ScratchBlock* unsorted = list;
1180 while (unsorted) {
1181 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1182 smallest->next = sorted;
1183 sorted = smallest;
1184 }
1185 list = sorted;
1186 }
1187
1188 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1189 size_t max_alloc_words) {
1190 ScratchBlock* res = NULL;
1191 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1192 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1193 sort_scratch_list(res);
1194 return res;
1195 }
1196
1197 void GenCollectedHeap::release_scratch() {
1198 _young_gen->reset_scratch();
1199 _old_gen->reset_scratch();
1200 }
1201
1202 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1203 void do_generation(Generation* gen) {
1204 gen->prepare_for_verify();
1205 }
1206 };
1207
1208 void GenCollectedHeap::prepare_for_verify() {
1209 ensure_parsability(false); // no need to retire TLABs
1210 GenPrepareForVerifyClosure blk;
1211 generation_iterate(&blk, false);
1212 }
1213
1214 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1215 bool old_to_young) {
1216 if (old_to_young) {
1217 cl->do_generation(_old_gen);
1218 cl->do_generation(_young_gen);
1219 } else {
1220 cl->do_generation(_young_gen);
1221 cl->do_generation(_old_gen);
1222 }
1223 }
1224
1225 bool GenCollectedHeap::is_maximal_no_gc() const {
1226 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1227 }
1228
1229 void GenCollectedHeap::save_marks() {
1230 _young_gen->save_marks();
1231 _old_gen->save_marks();
1232 }
1233
1234 GenCollectedHeap* GenCollectedHeap::heap() {
1235 CollectedHeap* heap = Universe::heap();
1236 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1237 assert(heap->kind() == CollectedHeap::Serial ||
1238 heap->kind() == CollectedHeap::CMS, "Invalid name");
1239 return (GenCollectedHeap*) heap;
1240 }
1241
1242 #if INCLUDE_SERIALGC
1243 void GenCollectedHeap::prepare_for_compaction() {
1244 // Start by compacting into same gen.
1245 CompactPoint cp(_old_gen);
1246 _old_gen->prepare_for_compaction(&cp);
1247 _young_gen->prepare_for_compaction(&cp);
1248 }
1249 #endif // INCLUDE_SERIALGC
1250
1251 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1252 log_debug(gc, verify)("%s", _old_gen->name());
1253 _old_gen->verify();
1254
1255 log_debug(gc, verify)("%s", _old_gen->name());
1256 _young_gen->verify();
1257
1258 log_debug(gc, verify)("RemSet");
1259 rem_set()->verify();
1260 }
1261
1262 void GenCollectedHeap::print_on(outputStream* st) const {
1263 _young_gen->print_on(st);
1264 _old_gen->print_on(st);
1265 MetaspaceUtils::print_on(st);
1266 }
1267
1268 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1269 }
1270
1271 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1272 }
1273
1274 void GenCollectedHeap::print_tracing_info() const {
1275 if (log_is_enabled(Debug, gc, heap, exit)) {
1276 LogStreamHandle(Debug, gc, heap, exit) lsh;
1277 _young_gen->print_summary_info_on(&lsh);
1278 _old_gen->print_summary_info_on(&lsh);
1279 }
1280 }
1281
1282 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1283 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1284 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1285 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1286 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1287 }
1288
1289 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1290 private:
1291 bool _full;
1292 public:
1293 void do_generation(Generation* gen) {
1294 gen->gc_prologue(_full);
1295 }
1296 GenGCPrologueClosure(bool full) : _full(full) {};
1297 };
1298
1299 void GenCollectedHeap::gc_prologue(bool full) {
1300 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1301
1302 // Fill TLAB's and such
1303 ensure_parsability(true); // retire TLABs
1304
1305 // Walk generations
1306 GenGCPrologueClosure blk(full);
1307 generation_iterate(&blk, false); // not old-to-young.
1308 };
1309
1310 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1311 private:
1312 bool _full;
1313 public:
1314 void do_generation(Generation* gen) {
1315 gen->gc_epilogue(_full);
1316 }
1317 GenGCEpilogueClosure(bool full) : _full(full) {};
1318 };
1319
1320 void GenCollectedHeap::gc_epilogue(bool full) {
1321 #if COMPILER2_OR_JVMCI
1322 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1323 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1324 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1325 #endif // COMPILER2_OR_JVMCI
1326
1327 resize_all_tlabs();
1328
1329 GenGCEpilogueClosure blk(full);
1330 generation_iterate(&blk, false); // not old-to-young.
1331
1332 if (!CleanChunkPoolAsync) {
1333 Chunk::clean_chunk_pool();
1334 }
1335
1336 MetaspaceCounters::update_performance_counters();
1337 CompressedClassSpaceCounters::update_performance_counters();
1338 };
1339
1340 #ifndef PRODUCT
1341 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1342 private:
1343 public:
1344 void do_generation(Generation* gen) {
1345 gen->record_spaces_top();
1346 }
1347 };
1348
1349 void GenCollectedHeap::record_gen_tops_before_GC() {
1350 if (ZapUnusedHeapArea) {
1351 GenGCSaveTopsBeforeGCClosure blk;
1352 generation_iterate(&blk, false); // not old-to-young.
1353 }
1354 }
1355 #endif // not PRODUCT
1356
1357 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1358 public:
1359 void do_generation(Generation* gen) {
1360 gen->ensure_parsability();
1361 }
1362 };
1363
1364 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1365 CollectedHeap::ensure_parsability(retire_tlabs);
1366 GenEnsureParsabilityClosure ep_cl;
1367 generation_iterate(&ep_cl, false);
1368 }
1369
1370 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1371 oop obj,
1372 size_t obj_size) {
1373 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1374 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1375 HeapWord* result = NULL;
1376
1377 result = old_gen->expand_and_allocate(obj_size, false);
1378
1379 if (result != NULL) {
1380 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1381 }
1382 return oop(result);
1383 }
1384
1385 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1386 jlong _time; // in ms
1387 jlong _now; // in ms
1388
1389 public:
1390 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1391
1392 jlong time() { return _time; }
1393
1394 void do_generation(Generation* gen) {
1395 _time = MIN2(_time, gen->time_of_last_gc(_now));
1396 }
1397 };
1398
1399 jlong GenCollectedHeap::millis_since_last_gc() {
1400 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1401 // provided the underlying platform provides such a time source
1402 // (and it is bug free). So we still have to guard against getting
1403 // back a time later than 'now'.
1404 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1405 GenTimeOfLastGCClosure tolgc_cl(now);
1406 // iterate over generations getting the oldest
1407 // time that a generation was collected
1408 generation_iterate(&tolgc_cl, false);
1409
1410 jlong retVal = now - tolgc_cl.time();
1411 if (retVal < 0) {
1412 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1413 ". returning zero instead.", retVal);
1414 return 0;
1415 }
1416 return retVal;
1417 }