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/genArguments.hpp"
46 #include "gc/shared/gcVMOperations.hpp"
47 #include "gc/shared/genCollectedHeap.hpp"
48 #include "gc/shared/genOopClosures.inline.hpp"
49 #include "gc/shared/generationSpec.hpp"
50 #include "gc/shared/oopStorageParState.inline.hpp"
51 #include "gc/shared/scavengableNMethods.hpp"
52 #include "gc/shared/space.hpp"
53 #include "gc/shared/strongRootsScope.hpp"
54 #include "gc/shared/weakProcessor.hpp"
55 #include "gc/shared/workgroup.hpp"
56 #include "memory/filemap.hpp"
57 #include "memory/metaspaceCounters.hpp"
58 #include "memory/resourceArea.hpp"
59 #include "memory/universe.hpp"
60 #include "oops/oop.inline.hpp"
61 #include "runtime/biasedLocking.hpp"
62 #include "runtime/flags/flagSetting.hpp"
63 #include "runtime/handles.hpp"
64 #include "runtime/handles.inline.hpp"
65 #include "runtime/java.hpp"
66 #include "runtime/vmThread.hpp"
67 #include "services/management.hpp"
68 #include "services/memoryService.hpp"
69 #include "utilities/debug.hpp"
70 #include "utilities/formatBuffer.hpp"
71 #include "utilities/macros.hpp"
72 #include "utilities/stack.inline.hpp"
73 #include "utilities/vmError.hpp"
74 #if INCLUDE_JVMCI
75 #include "jvmci/jvmci.hpp"
76 #endif
77
78 GenCollectedHeap::GenCollectedHeap(Generation::Name young,
79 Generation::Name old,
80 const char* policy_counters_name) :
81 CollectedHeap(),
82 _young_gen_spec(new GenerationSpec(young,
83 NewSize,
84 MaxNewSize,
85 GenAlignment)),
86 _old_gen_spec(new GenerationSpec(old,
87 OldSize,
88 MaxOldSize,
89 GenAlignment)),
90 _rem_set(NULL),
91 _soft_ref_gen_policy(),
92 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
93 _full_collections_completed(0),
94 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)) {
95 }
96
97 jint GenCollectedHeap::initialize() {
98 // While there are no constraints in the GC code that HeapWordSize
99 // be any particular value, there are multiple other areas in the
100 // system which believe this to be true (e.g. oop->object_size in some
101 // cases incorrectly returns the size in wordSize units rather than
102 // HeapWordSize).
103 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
104
105 // Allocate space for the heap.
106
107 char* heap_address;
108 ReservedSpace heap_rs;
109
110 heap_address = allocate(HeapAlignment, &heap_rs);
111
112 if (!heap_rs.is_reserved()) {
113 vm_shutdown_during_initialization(
114 "Could not reserve enough space for object heap");
115 return JNI_ENOMEM;
116 }
117
118 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
119
120 _rem_set = create_rem_set(reserved_region());
121 _rem_set->initialize();
122 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
123 bs->initialize();
124 BarrierSet::set_barrier_set(bs);
125
126 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false);
127 _young_gen = _young_gen_spec->init(young_rs, rem_set());
128 heap_rs = heap_rs.last_part(_young_gen_spec->max_size());
129
130 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false);
131 _old_gen = _old_gen_spec->init(old_rs, rem_set());
132 clear_incremental_collection_failed();
133
134 return JNI_OK;
135 }
136
137 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
138 return new CardTableRS(reserved_region, false /* scan_concurrently */);
139 }
140
141 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
142 size_t init_promo_size,
143 size_t init_survivor_size) {
144 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
145 _size_policy = new AdaptiveSizePolicy(init_eden_size,
146 init_promo_size,
147 init_survivor_size,
148 max_gc_pause_sec,
149 GCTimeRatio);
150 }
151
152 char* GenCollectedHeap::allocate(size_t alignment,
153 ReservedSpace* heap_rs){
154 // Now figure out the total size.
155 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
156 assert(alignment % pageSize == 0, "Must be");
157
158 // Check for overflow.
159 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
160 if (total_reserved < _young_gen_spec->max_size()) {
161 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
162 "the maximum representable size");
163 }
164 assert(total_reserved % alignment == 0,
165 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
166 SIZE_FORMAT, total_reserved, alignment);
167
168 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
169
170 os::trace_page_sizes("Heap",
171 MinHeapSize,
172 total_reserved,
173 alignment,
174 heap_rs->base(),
175 heap_rs->size());
176
177 return heap_rs->base();
178 }
179
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 static GenIsScavengable _is_scavengable;
188
189 void GenCollectedHeap::post_initialize() {
190 CollectedHeap::post_initialize();
191 ref_processing_init();
192
193 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
194
195 initialize_size_policy(def_new_gen->eden()->capacity(),
196 _old_gen->capacity(),
197 def_new_gen->from()->capacity());
198
199 MarkSweep::initialize();
200
201 ScavengableNMethods::initialize(&_is_scavengable);
202 }
203
204 void GenCollectedHeap::ref_processing_init() {
205 _young_gen->ref_processor_init();
206 _old_gen->ref_processor_init();
207 }
208
209 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
210 return _young_gen_spec;
211 }
212
213 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
214 return _old_gen_spec;
215 }
216
217 size_t GenCollectedHeap::capacity() const {
218 return _young_gen->capacity() + _old_gen->capacity();
219 }
220
221 size_t GenCollectedHeap::used() const {
222 return _young_gen->used() + _old_gen->used();
223 }
224
225 void GenCollectedHeap::save_used_regions() {
226 _old_gen->save_used_region();
227 _young_gen->save_used_region();
228 }
229
230 size_t GenCollectedHeap::max_capacity() const {
231 return _young_gen->max_capacity() + _old_gen->max_capacity();
232 }
233
234 // Update the _full_collections_completed counter
235 // at the end of a stop-world full GC.
236 unsigned int GenCollectedHeap::update_full_collections_completed() {
237 MonitorLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
238 assert(_full_collections_completed <= _total_full_collections,
239 "Can't complete more collections than were started");
240 _full_collections_completed = _total_full_collections;
241 ml.notify_all();
242 return _full_collections_completed;
243 }
244
245 // Update the _full_collections_completed counter, as appropriate,
246 // at the end of a concurrent GC cycle. Note the conditional update
247 // below to allow this method to be called by a concurrent collector
248 // without synchronizing in any manner with the VM thread (which
249 // may already have initiated a STW full collection "concurrently").
250 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
251 MonitorLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
252 assert((_full_collections_completed <= _total_full_collections) &&
253 (count <= _total_full_collections),
254 "Can't complete more collections than were started");
255 if (count > _full_collections_completed) {
256 _full_collections_completed = count;
257 ml.notify_all();
258 }
259 return _full_collections_completed;
260 }
261
262 // Return true if any of the following is true:
263 // . the allocation won't fit into the current young gen heap
264 // . gc locker is occupied (jni critical section)
265 // . heap memory is tight -- the most recent previous collection
266 // was a full collection because a partial collection (would
267 // have) failed and is likely to fail again
268 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
269 size_t young_capacity = _young_gen->capacity_before_gc();
270 return (word_size > heap_word_size(young_capacity))
271 || GCLocker::is_active_and_needs_gc()
272 || incremental_collection_failed();
273 }
274
275 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
276 HeapWord* result = NULL;
277 if (_old_gen->should_allocate(size, is_tlab)) {
278 result = _old_gen->expand_and_allocate(size, is_tlab);
279 }
280 if (result == NULL) {
281 if (_young_gen->should_allocate(size, is_tlab)) {
282 result = _young_gen->expand_and_allocate(size, is_tlab);
283 }
284 }
285 assert(result == NULL || is_in_reserved(result), "result not in heap");
286 return result;
287 }
288
289 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
290 bool is_tlab,
291 bool* gc_overhead_limit_was_exceeded) {
292 // In general gc_overhead_limit_was_exceeded should be false so
293 // set it so here and reset it to true only if the gc time
294 // limit is being exceeded as checked below.
295 *gc_overhead_limit_was_exceeded = false;
296
297 HeapWord* result = NULL;
298
299 // Loop until the allocation is satisfied, or unsatisfied after GC.
300 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
301 HandleMark hm; // Discard any handles allocated in each iteration.
302
303 // First allocation attempt is lock-free.
304 Generation *young = _young_gen;
305 assert(young->supports_inline_contig_alloc(),
306 "Otherwise, must do alloc within heap lock");
307 if (young->should_allocate(size, is_tlab)) {
308 result = young->par_allocate(size, is_tlab);
309 if (result != NULL) {
310 assert(is_in_reserved(result), "result not in heap");
311 return result;
312 }
313 }
314 uint gc_count_before; // Read inside the Heap_lock locked region.
315 {
316 MutexLocker ml(Heap_lock);
317 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
318 // Note that only large objects get a shot at being
319 // allocated in later generations.
320 bool first_only = !should_try_older_generation_allocation(size);
321
322 result = attempt_allocation(size, is_tlab, first_only);
323 if (result != NULL) {
324 assert(is_in_reserved(result), "result not in heap");
325 return result;
326 }
327
328 if (GCLocker::is_active_and_needs_gc()) {
329 if (is_tlab) {
330 return NULL; // Caller will retry allocating individual object.
331 }
332 if (!is_maximal_no_gc()) {
333 // Try and expand heap to satisfy request.
334 result = expand_heap_and_allocate(size, is_tlab);
335 // Result could be null if we are out of space.
336 if (result != NULL) {
337 return result;
338 }
339 }
340
341 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
342 return NULL; // We didn't get to do a GC and we didn't get any memory.
343 }
344
345 // If this thread is not in a jni critical section, we stall
346 // the requestor until the critical section has cleared and
347 // GC allowed. When the critical section clears, a GC is
348 // initiated by the last thread exiting the critical section; so
349 // we retry the allocation sequence from the beginning of the loop,
350 // rather than causing more, now probably unnecessary, GC attempts.
351 JavaThread* jthr = JavaThread::current();
352 if (!jthr->in_critical()) {
353 MutexUnlocker mul(Heap_lock);
354 // Wait for JNI critical section to be exited
355 GCLocker::stall_until_clear();
356 gclocker_stalled_count += 1;
357 continue;
358 } else {
359 if (CheckJNICalls) {
360 fatal("Possible deadlock due to allocating while"
361 " in jni critical section");
362 }
363 return NULL;
364 }
365 }
366
367 // Read the gc count while the heap lock is held.
368 gc_count_before = total_collections();
369 }
370
371 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
372 VMThread::execute(&op);
373 if (op.prologue_succeeded()) {
374 result = op.result();
375 if (op.gc_locked()) {
376 assert(result == NULL, "must be NULL if gc_locked() is true");
377 continue; // Retry and/or stall as necessary.
378 }
379
380 // Allocation has failed and a collection
381 // has been done. If the gc time limit was exceeded the
382 // this time, return NULL so that an out-of-memory
383 // will be thrown. Clear gc_overhead_limit_exceeded
384 // so that the overhead exceeded does not persist.
385
386 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
387 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
388
389 if (limit_exceeded && softrefs_clear) {
390 *gc_overhead_limit_was_exceeded = true;
391 size_policy()->set_gc_overhead_limit_exceeded(false);
392 if (op.result() != NULL) {
393 CollectedHeap::fill_with_object(op.result(), size);
394 }
395 return NULL;
396 }
397 assert(result == NULL || is_in_reserved(result),
398 "result not in heap");
399 return result;
400 }
401
402 // Give a warning if we seem to be looping forever.
403 if ((QueuedAllocationWarningCount > 0) &&
404 (try_count % QueuedAllocationWarningCount == 0)) {
405 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
406 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
407 }
408 }
409 }
410
411 #ifndef PRODUCT
412 // Override of memory state checking method in CollectedHeap:
413 // Some collectors (CMS for example) can't have badHeapWordVal written
414 // in the first two words of an object. (For instance , in the case of
415 // CMS these words hold state used to synchronize between certain
416 // (concurrent) GC steps and direct allocating mutators.)
417 // The skip_header_HeapWords() method below, allows us to skip
418 // over the requisite number of HeapWord's. Note that (for
419 // generational collectors) this means that those many words are
420 // skipped in each object, irrespective of the generation in which
421 // that object lives. The resultant loss of precision seems to be
422 // harmless and the pain of avoiding that imprecision appears somewhat
423 // higher than we are prepared to pay for such rudimentary debugging
424 // support.
425 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
426 size_t size) {
427 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
428 // We are asked to check a size in HeapWords,
429 // but the memory is mangled in juint words.
430 juint* start = (juint*) (addr + skip_header_HeapWords());
431 juint* end = (juint*) (addr + size);
432 for (juint* slot = start; slot < end; slot += 1) {
433 assert(*slot == badHeapWordVal,
434 "Found non badHeapWordValue in pre-allocation check");
435 }
436 }
437 }
438 #endif
439
440 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
441 bool is_tlab,
442 bool first_only) {
443 HeapWord* res = NULL;
444
445 if (_young_gen->should_allocate(size, is_tlab)) {
446 res = _young_gen->allocate(size, is_tlab);
447 if (res != NULL || first_only) {
448 return res;
449 }
450 }
451
452 if (_old_gen->should_allocate(size, is_tlab)) {
453 res = _old_gen->allocate(size, is_tlab);
454 }
455
456 return res;
457 }
458
459 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
460 bool* gc_overhead_limit_was_exceeded) {
461 return mem_allocate_work(size,
462 false /* is_tlab */,
463 gc_overhead_limit_was_exceeded);
464 }
465
466 bool GenCollectedHeap::must_clear_all_soft_refs() {
467 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
468 _gc_cause == GCCause::_wb_full_gc;
469 }
470
471 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
472 bool is_tlab, bool run_verification, bool clear_soft_refs,
473 bool restore_marks_for_biased_locking) {
474 FormatBuffer<> title("Collect gen: %s", gen->short_name());
475 GCTraceTime(Trace, gc, phases) t1(title);
476 TraceCollectorStats tcs(gen->counters());
477 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
478
479 gen->stat_record()->invocations++;
480 gen->stat_record()->accumulated_time.start();
481
482 // Must be done anew before each collection because
483 // a previous collection will do mangling and will
484 // change top of some spaces.
485 record_gen_tops_before_GC();
486
487 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
488
489 if (run_verification && VerifyBeforeGC) {
490 HandleMark hm; // Discard invalid handles created during verification
491 Universe::verify("Before GC");
492 }
493 COMPILER2_PRESENT(DerivedPointerTable::clear());
494
495 if (restore_marks_for_biased_locking) {
496 // We perform this mark word preservation work lazily
497 // because it's only at this point that we know whether we
498 // absolutely have to do it; we want to avoid doing it for
499 // scavenge-only collections where it's unnecessary
500 BiasedLocking::preserve_marks();
501 }
502
503 // Do collection work
504 {
505 // Note on ref discovery: For what appear to be historical reasons,
506 // GCH enables and disabled (by enqueing) refs discovery.
507 // In the future this should be moved into the generation's
508 // collect method so that ref discovery and enqueueing concerns
509 // are local to a generation. The collect method could return
510 // an appropriate indication in the case that notification on
511 // the ref lock was needed. This will make the treatment of
512 // weak refs more uniform (and indeed remove such concerns
513 // from GCH). XXX
514
515 HandleMark hm; // Discard invalid handles created during gc
516 save_marks(); // save marks for all gens
517 // We want to discover references, but not process them yet.
518 // This mode is disabled in process_discovered_references if the
519 // generation does some collection work, or in
520 // enqueue_discovered_references if the generation returns
521 // without doing any work.
522 ReferenceProcessor* rp = gen->ref_processor();
523 // If the discovery of ("weak") refs in this generation is
524 // atomic wrt other collectors in this configuration, we
525 // are guaranteed to have empty discovered ref lists.
526 if (rp->discovery_is_atomic()) {
527 rp->enable_discovery();
528 rp->setup_policy(clear_soft_refs);
529 } else {
530 // collect() below will enable discovery as appropriate
531 }
532 gen->collect(full, clear_soft_refs, size, is_tlab);
533 if (!rp->enqueuing_is_done()) {
534 rp->disable_discovery();
535 } else {
536 rp->set_enqueuing_is_done(false);
537 }
538 rp->verify_no_references_recorded();
539 }
540
541 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
542
543 gen->stat_record()->accumulated_time.stop();
544
545 update_gc_stats(gen, full);
546
547 if (run_verification && VerifyAfterGC) {
548 HandleMark hm; // Discard invalid handles created during verification
549 Universe::verify("After GC");
550 }
551 }
552
553 void GenCollectedHeap::do_collection(bool full,
554 bool clear_all_soft_refs,
555 size_t size,
556 bool is_tlab,
557 GenerationType max_generation) {
558 ResourceMark rm;
559 DEBUG_ONLY(Thread* my_thread = Thread::current();)
560
561 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
562 assert(my_thread->is_VM_thread() ||
563 my_thread->is_ConcurrentGC_thread(),
564 "incorrect thread type capability");
565 assert(Heap_lock->is_locked(),
566 "the requesting thread should have the Heap_lock");
567 guarantee(!is_gc_active(), "collection is not reentrant");
568
569 if (GCLocker::check_active_before_gc()) {
570 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
571 }
572
573 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
574 soft_ref_policy()->should_clear_all_soft_refs();
575
576 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
577
578 FlagSetting fl(_is_gc_active, true);
579
580 bool complete = full && (max_generation == OldGen);
581 bool old_collects_young = complete && !ScavengeBeforeFullGC;
582 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
583
584 size_t young_prev_used = _young_gen->used();
585 size_t old_prev_used = _old_gen->used();
586 const metaspace::MetaspaceSizesSnapshot prev_meta_sizes;
587
588 bool run_verification = total_collections() >= VerifyGCStartAt;
589 bool prepared_for_verification = false;
590 bool do_full_collection = false;
591
592 if (do_young_collection) {
593 GCIdMark gc_id_mark;
594 GCTraceCPUTime tcpu;
595 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true);
596
597 print_heap_before_gc();
598
599 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
600 prepare_for_verify();
601 prepared_for_verification = true;
602 }
603
604 gc_prologue(complete);
605 increment_total_collections(complete);
606
607 collect_generation(_young_gen,
608 full,
609 size,
610 is_tlab,
611 run_verification && VerifyGCLevel <= 0,
612 do_clear_all_soft_refs,
613 false);
614
615 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
616 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
617 // Allocation request was met by young GC.
618 size = 0;
619 }
620
621 // Ask if young collection is enough. If so, do the final steps for young collection,
622 // and fallthrough to the end.
623 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
624 if (!do_full_collection) {
625 // Adjust generation sizes.
626 _young_gen->compute_new_size();
627
628 print_heap_change(young_prev_used, old_prev_used);
629 MetaspaceUtils::print_metaspace_change(prev_meta_sizes);
630
631 // Track memory usage and detect low memory after GC finishes
632 MemoryService::track_memory_usage();
633
634 gc_epilogue(complete);
635 }
636
637 print_heap_after_gc();
638
639 } else {
640 // No young collection, ask if we need to perform Full collection.
641 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
642 }
643
644 if (do_full_collection) {
645 GCIdMark gc_id_mark;
646 GCTraceCPUTime tcpu;
647 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
648
649 print_heap_before_gc();
650
651 if (!prepared_for_verification && run_verification &&
652 VerifyGCLevel <= 1 && VerifyBeforeGC) {
653 prepare_for_verify();
654 }
655
656 if (!do_young_collection) {
657 gc_prologue(complete);
658 increment_total_collections(complete);
659 }
660
661 // Accounting quirk: total full collections would be incremented when "complete"
662 // is set, by calling increment_total_collections above. However, we also need to
663 // account Full collections that had "complete" unset.
664 if (!complete) {
665 increment_total_full_collections();
666 }
667
668 collect_generation(_old_gen,
669 full,
670 size,
671 is_tlab,
672 run_verification && VerifyGCLevel <= 1,
673 do_clear_all_soft_refs,
674 true);
675
676 // Adjust generation sizes.
677 _old_gen->compute_new_size();
678 _young_gen->compute_new_size();
679
680 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
681 ClassLoaderDataGraph::purge();
682 MetaspaceUtils::verify_metrics();
683 // Resize the metaspace capacity after full collections
684 MetaspaceGC::compute_new_size();
685 update_full_collections_completed();
686
687 print_heap_change(young_prev_used, old_prev_used);
688 MetaspaceUtils::print_metaspace_change(prev_meta_sizes);
689
690 // Track memory usage and detect low memory after GC finishes
691 MemoryService::track_memory_usage();
692
693 // Need to tell the epilogue code we are done with Full GC, regardless what was
694 // the initial value for "complete" flag.
695 gc_epilogue(true);
696
697 BiasedLocking::restore_marks();
698
699 print_heap_after_gc();
700 }
701
702 #ifdef TRACESPINNING
703 ParallelTaskTerminator::print_termination_counts();
704 #endif
705 }
706
707 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
708 GenCollectedHeap::GenerationType max_gen) const {
709 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
710 }
711
712 void GenCollectedHeap::register_nmethod(nmethod* nm) {
713 ScavengableNMethods::register_nmethod(nm);
714 }
715
716 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
717 ScavengableNMethods::unregister_nmethod(nm);
718 }
719
720 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
721 ScavengableNMethods::verify_nmethod(nm);
722 }
723
724 void GenCollectedHeap::flush_nmethod(nmethod* nm) {
725 // Do nothing.
726 }
727
728 void GenCollectedHeap::prune_scavengable_nmethods() {
729 ScavengableNMethods::prune_nmethods();
730 }
731
732 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
733 GCCauseSetter x(this, GCCause::_allocation_failure);
734 HeapWord* result = NULL;
735
736 assert(size != 0, "Precondition violated");
737 if (GCLocker::is_active_and_needs_gc()) {
738 // GC locker is active; instead of a collection we will attempt
739 // to expand the heap, if there's room for expansion.
740 if (!is_maximal_no_gc()) {
741 result = expand_heap_and_allocate(size, is_tlab);
742 }
743 return result; // Could be null if we are out of space.
744 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
745 // Do an incremental collection.
746 do_collection(false, // full
747 false, // clear_all_soft_refs
748 size, // size
749 is_tlab, // is_tlab
750 GenCollectedHeap::OldGen); // max_generation
751 } else {
752 log_trace(gc)(" :: Trying full because partial may fail :: ");
753 // Try a full collection; see delta for bug id 6266275
754 // for the original code and why this has been simplified
755 // with from-space allocation criteria modified and
756 // such allocation moved out of the safepoint path.
757 do_collection(true, // full
758 false, // clear_all_soft_refs
759 size, // size
760 is_tlab, // is_tlab
761 GenCollectedHeap::OldGen); // max_generation
762 }
763
764 result = attempt_allocation(size, is_tlab, false /*first_only*/);
765
766 if (result != NULL) {
767 assert(is_in_reserved(result), "result not in heap");
768 return result;
769 }
770
771 // OK, collection failed, try expansion.
772 result = expand_heap_and_allocate(size, is_tlab);
773 if (result != NULL) {
774 return result;
775 }
776
777 // If we reach this point, we're really out of memory. Try every trick
778 // we can to reclaim memory. Force collection of soft references. Force
779 // a complete compaction of the heap. Any additional methods for finding
780 // free memory should be here, especially if they are expensive. If this
781 // attempt fails, an OOM exception will be thrown.
782 {
783 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
784
785 do_collection(true, // full
786 true, // clear_all_soft_refs
787 size, // size
788 is_tlab, // is_tlab
789 GenCollectedHeap::OldGen); // max_generation
790 }
791
792 result = attempt_allocation(size, is_tlab, false /* first_only */);
793 if (result != NULL) {
794 assert(is_in_reserved(result), "result not in heap");
795 return result;
796 }
797
798 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
799 "Flag should have been handled and cleared prior to this point");
800
801 // What else? We might try synchronous finalization later. If the total
802 // space available is large enough for the allocation, then a more
803 // complete compaction phase than we've tried so far might be
804 // appropriate.
805 return NULL;
806 }
807
808 #ifdef ASSERT
809 class AssertNonScavengableClosure: public OopClosure {
810 public:
811 virtual void do_oop(oop* p) {
812 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
813 "Referent should not be scavengable."); }
814 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
815 };
816 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
817 #endif
818
819 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
820 ScanningOption so,
821 OopClosure* strong_roots,
822 CLDClosure* strong_cld_closure,
823 CLDClosure* weak_cld_closure,
824 CodeBlobToOopClosure* code_roots) {
825 // General roots.
826 assert(code_roots != NULL, "code root closure should always be set");
827 // _n_termination for _process_strong_tasks should be set up stream
828 // in a method not running in a GC worker. Otherwise the GC worker
829 // could be trying to change the termination condition while the task
830 // is executing in another GC worker.
831
832 if (_process_strong_tasks->try_claim_task(GCH_PS_ClassLoaderDataGraph_oops_do)) {
833 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
834 }
835
836 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
837 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
838
839 bool is_par = scope->n_threads() > 1;
840 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
841
842 if (_process_strong_tasks->try_claim_task(GCH_PS_Universe_oops_do)) {
843 Universe::oops_do(strong_roots);
844 }
845 // Global (strong) JNI handles
846 if (_process_strong_tasks->try_claim_task(GCH_PS_JNIHandles_oops_do)) {
847 JNIHandles::oops_do(strong_roots);
848 }
849
850 if (_process_strong_tasks->try_claim_task(GCH_PS_ObjectSynchronizer_oops_do)) {
851 ObjectSynchronizer::oops_do(strong_roots);
852 }
853 if (_process_strong_tasks->try_claim_task(GCH_PS_Management_oops_do)) {
854 Management::oops_do(strong_roots);
855 }
856 if (_process_strong_tasks->try_claim_task(GCH_PS_jvmti_oops_do)) {
857 JvmtiExport::oops_do(strong_roots);
858 }
859 #if INCLUDE_AOT
860 if (UseAOT && _process_strong_tasks->try_claim_task(GCH_PS_aot_oops_do)) {
861 AOTLoader::oops_do(strong_roots);
862 }
863 #endif
864 if (_process_strong_tasks->try_claim_task(GCH_PS_SystemDictionary_oops_do)) {
865 SystemDictionary::oops_do(strong_roots);
866 }
867
868 if (_process_strong_tasks->try_claim_task(GCH_PS_CodeCache_oops_do)) {
869 if (so & SO_ScavengeCodeCache) {
870 assert(code_roots != NULL, "must supply closure for code cache");
871
872 // We only visit parts of the CodeCache when scavenging.
873 ScavengableNMethods::nmethods_do(code_roots);
874 }
875 if (so & SO_AllCodeCache) {
876 assert(code_roots != NULL, "must supply closure for code cache");
877
878 // CMSCollector uses this to do intermediate-strength collections.
879 // We scan the entire code cache, since CodeCache::do_unloading is not called.
880 CodeCache::blobs_do(code_roots);
881 }
882 // Verify that the code cache contents are not subject to
883 // movement by a scavenging collection.
884 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
885 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
886 }
887 }
888
889 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
890 OopsInGenClosure* root_closure,
891 OopsInGenClosure* old_gen_closure,
892 CLDClosure* cld_closure) {
893 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
894
895 process_roots(scope, SO_ScavengeCodeCache, root_closure,
896 cld_closure, cld_closure, &mark_code_closure);
897
898 if (_process_strong_tasks->try_claim_task(GCH_PS_younger_gens)) {
899 root_closure->reset_generation();
900 }
901
902 // When collection is parallel, all threads get to cooperate to do
903 // old generation scanning.
904 old_gen_closure->set_generation(_old_gen);
905 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
906 old_gen_closure->reset_generation();
907
908 _process_strong_tasks->all_tasks_completed(scope->n_threads());
909 }
910
911 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
912 bool is_adjust_phase,
913 ScanningOption so,
914 bool only_strong_roots,
915 OopsInGenClosure* root_closure,
916 CLDClosure* cld_closure) {
917 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
918 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
919
920 process_roots(scope, so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
921 _process_strong_tasks->all_tasks_completed(scope->n_threads());
922 }
923
924 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
925 WeakProcessor::oops_do(root_closure);
926 _young_gen->ref_processor()->weak_oops_do(root_closure);
927 _old_gen->ref_processor()->weak_oops_do(root_closure);
928 }
929
930 bool GenCollectedHeap::no_allocs_since_save_marks() {
931 return _young_gen->no_allocs_since_save_marks() &&
932 _old_gen->no_allocs_since_save_marks();
933 }
934
935 bool GenCollectedHeap::supports_inline_contig_alloc() const {
936 return _young_gen->supports_inline_contig_alloc();
937 }
938
939 HeapWord* volatile* GenCollectedHeap::top_addr() const {
940 return _young_gen->top_addr();
941 }
942
943 HeapWord** GenCollectedHeap::end_addr() const {
944 return _young_gen->end_addr();
945 }
946
947 // public collection interfaces
948
949 void GenCollectedHeap::collect(GCCause::Cause cause) {
950 if ((cause == GCCause::_wb_young_gc) ||
951 (cause == GCCause::_gc_locker)) {
952 // Young collection for WhiteBox or GCLocker.
953 collect(cause, YoungGen);
954 } else {
955 #ifdef ASSERT
956 if (cause == GCCause::_scavenge_alot) {
957 // Young collection only.
958 collect(cause, YoungGen);
959 } else {
960 // Stop-the-world full collection.
961 collect(cause, OldGen);
962 }
963 #else
964 // Stop-the-world full collection.
965 collect(cause, OldGen);
966 #endif
967 }
968 }
969
970 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
971 // The caller doesn't have the Heap_lock
972 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
973 MutexLocker ml(Heap_lock);
974 collect_locked(cause, max_generation);
975 }
976
977 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
978 // The caller has the Heap_lock
979 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
980 collect_locked(cause, OldGen);
981 }
982
983 // this is the private collection interface
984 // The Heap_lock is expected to be held on entry.
985
986 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
987 // Read the GC count while holding the Heap_lock
988 unsigned int gc_count_before = total_collections();
989 unsigned int full_gc_count_before = total_full_collections();
990
991 if (GCLocker::should_discard(cause, gc_count_before)) {
992 return;
993 }
994
995 {
996 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
997 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
998 cause, max_generation);
999 VMThread::execute(&op);
1000 }
1001 }
1002
1003 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1004 do_full_collection(clear_all_soft_refs, OldGen);
1005 }
1006
1007 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
1008 GenerationType last_generation) {
1009 do_collection(true, // full
1010 clear_all_soft_refs, // clear_all_soft_refs
1011 0, // size
1012 false, // is_tlab
1013 last_generation); // last_generation
1014 // Hack XXX FIX ME !!!
1015 // A scavenge may not have been attempted, or may have
1016 // been attempted and failed, because the old gen was too full
1017 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
1018 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1019 // This time allow the old gen to be collected as well
1020 do_collection(true, // full
1021 clear_all_soft_refs, // clear_all_soft_refs
1022 0, // size
1023 false, // is_tlab
1024 OldGen); // last_generation
1025 }
1026 }
1027
1028 bool GenCollectedHeap::is_in_young(oop p) {
1029 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1030 assert(result == _young_gen->is_in_reserved(p),
1031 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1032 return result;
1033 }
1034
1035 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1036 bool GenCollectedHeap::is_in(const void* p) const {
1037 return _young_gen->is_in(p) || _old_gen->is_in(p);
1038 }
1039
1040 #ifdef ASSERT
1041 // Don't implement this by using is_in_young(). This method is used
1042 // in some cases to check that is_in_young() is correct.
1043 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1044 assert(is_in_reserved(p) || p == NULL,
1045 "Does not work if address is non-null and outside of the heap");
1046 return p < _young_gen->reserved().end() && p != NULL;
1047 }
1048 #endif
1049
1050 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
1051 _young_gen->oop_iterate(cl);
1052 _old_gen->oop_iterate(cl);
1053 }
1054
1055 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1056 _young_gen->object_iterate(cl);
1057 _old_gen->object_iterate(cl);
1058 }
1059
1060 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1061 _young_gen->safe_object_iterate(cl);
1062 _old_gen->safe_object_iterate(cl);
1063 }
1064
1065 Space* GenCollectedHeap::space_containing(const void* addr) const {
1066 Space* res = _young_gen->space_containing(addr);
1067 if (res != NULL) {
1068 return res;
1069 }
1070 res = _old_gen->space_containing(addr);
1071 assert(res != NULL, "Could not find containing space");
1072 return res;
1073 }
1074
1075 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1076 assert(is_in_reserved(addr), "block_start of address outside of heap");
1077 if (_young_gen->is_in_reserved(addr)) {
1078 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1079 return _young_gen->block_start(addr);
1080 }
1081
1082 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1083 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1084 return _old_gen->block_start(addr);
1085 }
1086
1087 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1088 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1089 assert(block_start(addr) == addr, "addr must be a block start");
1090 if (_young_gen->is_in_reserved(addr)) {
1091 return _young_gen->block_is_obj(addr);
1092 }
1093
1094 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1095 return _old_gen->block_is_obj(addr);
1096 }
1097
1098 bool GenCollectedHeap::supports_tlab_allocation() const {
1099 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1100 return _young_gen->supports_tlab_allocation();
1101 }
1102
1103 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1104 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1105 if (_young_gen->supports_tlab_allocation()) {
1106 return _young_gen->tlab_capacity();
1107 }
1108 return 0;
1109 }
1110
1111 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1112 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1113 if (_young_gen->supports_tlab_allocation()) {
1114 return _young_gen->tlab_used();
1115 }
1116 return 0;
1117 }
1118
1119 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1120 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1121 if (_young_gen->supports_tlab_allocation()) {
1122 return _young_gen->unsafe_max_tlab_alloc();
1123 }
1124 return 0;
1125 }
1126
1127 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1128 size_t requested_size,
1129 size_t* actual_size) {
1130 bool gc_overhead_limit_was_exceeded;
1131 HeapWord* result = mem_allocate_work(requested_size /* size */,
1132 true /* is_tlab */,
1133 &gc_overhead_limit_was_exceeded);
1134 if (result != NULL) {
1135 *actual_size = requested_size;
1136 }
1137
1138 return result;
1139 }
1140
1141 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1142 // from the list headed by "*prev_ptr".
1143 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1144 bool first = true;
1145 size_t min_size = 0; // "first" makes this conceptually infinite.
1146 ScratchBlock **smallest_ptr, *smallest;
1147 ScratchBlock *cur = *prev_ptr;
1148 while (cur) {
1149 assert(*prev_ptr == cur, "just checking");
1150 if (first || cur->num_words < min_size) {
1151 smallest_ptr = prev_ptr;
1152 smallest = cur;
1153 min_size = smallest->num_words;
1154 first = false;
1155 }
1156 prev_ptr = &cur->next;
1157 cur = cur->next;
1158 }
1159 smallest = *smallest_ptr;
1160 *smallest_ptr = smallest->next;
1161 return smallest;
1162 }
1163
1164 // Sort the scratch block list headed by res into decreasing size order,
1165 // and set "res" to the result.
1166 static void sort_scratch_list(ScratchBlock*& list) {
1167 ScratchBlock* sorted = NULL;
1168 ScratchBlock* unsorted = list;
1169 while (unsorted) {
1170 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1171 smallest->next = sorted;
1172 sorted = smallest;
1173 }
1174 list = sorted;
1175 }
1176
1177 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1178 size_t max_alloc_words) {
1179 ScratchBlock* res = NULL;
1180 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1181 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1182 sort_scratch_list(res);
1183 return res;
1184 }
1185
1186 void GenCollectedHeap::release_scratch() {
1187 _young_gen->reset_scratch();
1188 _old_gen->reset_scratch();
1189 }
1190
1191 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1192 void do_generation(Generation* gen) {
1193 gen->prepare_for_verify();
1194 }
1195 };
1196
1197 void GenCollectedHeap::prepare_for_verify() {
1198 ensure_parsability(false); // no need to retire TLABs
1199 GenPrepareForVerifyClosure blk;
1200 generation_iterate(&blk, false);
1201 }
1202
1203 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1204 bool old_to_young) {
1205 if (old_to_young) {
1206 cl->do_generation(_old_gen);
1207 cl->do_generation(_young_gen);
1208 } else {
1209 cl->do_generation(_young_gen);
1210 cl->do_generation(_old_gen);
1211 }
1212 }
1213
1214 bool GenCollectedHeap::is_maximal_no_gc() const {
1215 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1216 }
1217
1218 void GenCollectedHeap::save_marks() {
1219 _young_gen->save_marks();
1220 _old_gen->save_marks();
1221 }
1222
1223 GenCollectedHeap* GenCollectedHeap::heap() {
1224 CollectedHeap* heap = Universe::heap();
1225 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1226 assert(heap->kind() == CollectedHeap::Serial ||
1227 heap->kind() == CollectedHeap::CMS, "Invalid name");
1228 return (GenCollectedHeap*) heap;
1229 }
1230
1231 #if INCLUDE_SERIALGC
1232 void GenCollectedHeap::prepare_for_compaction() {
1233 // Start by compacting into same gen.
1234 CompactPoint cp(_old_gen);
1235 _old_gen->prepare_for_compaction(&cp);
1236 _young_gen->prepare_for_compaction(&cp);
1237 }
1238 #endif // INCLUDE_SERIALGC
1239
1240 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1241 log_debug(gc, verify)("%s", _old_gen->name());
1242 _old_gen->verify();
1243
1244 log_debug(gc, verify)("%s", _old_gen->name());
1245 _young_gen->verify();
1246
1247 log_debug(gc, verify)("RemSet");
1248 rem_set()->verify();
1249 }
1250
1251 void GenCollectedHeap::print_on(outputStream* st) const {
1252 _young_gen->print_on(st);
1253 _old_gen->print_on(st);
1254 MetaspaceUtils::print_on(st);
1255 }
1256
1257 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1258 }
1259
1260 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1261 }
1262
1263 void GenCollectedHeap::print_tracing_info() const {
1264 if (log_is_enabled(Debug, gc, heap, exit)) {
1265 LogStreamHandle(Debug, gc, heap, exit) lsh;
1266 _young_gen->print_summary_info_on(&lsh);
1267 _old_gen->print_summary_info_on(&lsh);
1268 }
1269 }
1270
1271 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1272 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1273 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1274 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1275 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1276 }
1277
1278 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1279 private:
1280 bool _full;
1281 public:
1282 void do_generation(Generation* gen) {
1283 gen->gc_prologue(_full);
1284 }
1285 GenGCPrologueClosure(bool full) : _full(full) {};
1286 };
1287
1288 void GenCollectedHeap::gc_prologue(bool full) {
1289 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1290
1291 // Fill TLAB's and such
1292 ensure_parsability(true); // retire TLABs
1293
1294 // Walk generations
1295 GenGCPrologueClosure blk(full);
1296 generation_iterate(&blk, false); // not old-to-young.
1297 };
1298
1299 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1300 private:
1301 bool _full;
1302 public:
1303 void do_generation(Generation* gen) {
1304 gen->gc_epilogue(_full);
1305 }
1306 GenGCEpilogueClosure(bool full) : _full(full) {};
1307 };
1308
1309 void GenCollectedHeap::gc_epilogue(bool full) {
1310 #if COMPILER2_OR_JVMCI
1311 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1312 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1313 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1314 #endif // COMPILER2_OR_JVMCI
1315
1316 resize_all_tlabs();
1317
1318 GenGCEpilogueClosure blk(full);
1319 generation_iterate(&blk, false); // not old-to-young.
1320
1321 if (!CleanChunkPoolAsync) {
1322 Chunk::clean_chunk_pool();
1323 }
1324
1325 MetaspaceCounters::update_performance_counters();
1326 CompressedClassSpaceCounters::update_performance_counters();
1327 };
1328
1329 #ifndef PRODUCT
1330 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1331 private:
1332 public:
1333 void do_generation(Generation* gen) {
1334 gen->record_spaces_top();
1335 }
1336 };
1337
1338 void GenCollectedHeap::record_gen_tops_before_GC() {
1339 if (ZapUnusedHeapArea) {
1340 GenGCSaveTopsBeforeGCClosure blk;
1341 generation_iterate(&blk, false); // not old-to-young.
1342 }
1343 }
1344 #endif // not PRODUCT
1345
1346 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1347 public:
1348 void do_generation(Generation* gen) {
1349 gen->ensure_parsability();
1350 }
1351 };
1352
1353 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1354 CollectedHeap::ensure_parsability(retire_tlabs);
1355 GenEnsureParsabilityClosure ep_cl;
1356 generation_iterate(&ep_cl, false);
1357 }
1358
1359 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1360 oop obj,
1361 size_t obj_size) {
1362 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1363 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1364 HeapWord* result = NULL;
1365
1366 result = old_gen->expand_and_allocate(obj_size, false);
1367
1368 if (result != NULL) {
1369 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1370 }
1371 return oop(result);
1372 }
1373
1374 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1375 jlong _time; // in ms
1376 jlong _now; // in ms
1377
1378 public:
1379 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1380
1381 jlong time() { return _time; }
1382
1383 void do_generation(Generation* gen) {
1384 _time = MIN2(_time, gen->time_of_last_gc(_now));
1385 }
1386 };
1387
1388 jlong GenCollectedHeap::millis_since_last_gc() {
1389 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1390 // provided the underlying platform provides such a time source
1391 // (and it is bug free). So we still have to guard against getting
1392 // back a time later than 'now'.
1393 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1394 GenTimeOfLastGCClosure tolgc_cl(now);
1395 // iterate over generations getting the oldest
1396 // time that a generation was collected
1397 generation_iterate(&tolgc_cl, false);
1398
1399 jlong retVal = now - tolgc_cl.time();
1400 if (retVal < 0) {
1401 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1402 ". returning zero instead.", retVal);
1403 return 0;
1404 }
1405 return retVal;
1406 }