1 /*
2 * Copyright (c) 2000, 2016, 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 "classfile/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc/shared/collectedHeap.inline.hpp"
32 #include "gc/shared/collectorCounters.hpp"
33 #include "gc/shared/gcId.hpp"
34 #include "gc/shared/gcLocker.inline.hpp"
35 #include "gc/shared/gcTrace.hpp"
36 #include "gc/shared/gcTraceTime.inline.hpp"
37 #include "gc/shared/genCollectedHeap.hpp"
38 #include "gc/shared/genOopClosures.inline.hpp"
39 #include "gc/shared/generationSpec.hpp"
40 #include "gc/shared/space.hpp"
41 #include "gc/shared/strongRootsScope.hpp"
42 #include "gc/shared/vmGCOperations.hpp"
43 #include "gc/shared/workgroup.hpp"
44 #include "memory/filemap.hpp"
45 #include "memory/resourceArea.hpp"
46 #include "oops/oop.inline.hpp"
47 #include "runtime/biasedLocking.hpp"
48 #include "runtime/fprofiler.hpp"
49 #include "runtime/handles.hpp"
50 #include "runtime/handles.inline.hpp"
51 #include "runtime/java.hpp"
52 #include "runtime/vmThread.hpp"
53 #include "services/management.hpp"
54 #include "services/memoryService.hpp"
55 #include "utilities/macros.hpp"
56 #include "utilities/stack.inline.hpp"
57 #include "utilities/vmError.hpp"
58 #if INCLUDE_ALL_GCS
59 #include "gc/cms/concurrentMarkSweepThread.hpp"
60 #include "gc/cms/vmCMSOperations.hpp"
61 #endif // INCLUDE_ALL_GCS
62
63 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
64
65 // The set of potentially parallel tasks in root scanning.
66 enum GCH_strong_roots_tasks {
67 GCH_PS_Universe_oops_do,
68 GCH_PS_JNIHandles_oops_do,
69 GCH_PS_ObjectSynchronizer_oops_do,
70 GCH_PS_FlatProfiler_oops_do,
71 GCH_PS_Management_oops_do,
72 GCH_PS_SystemDictionary_oops_do,
73 GCH_PS_ClassLoaderDataGraph_oops_do,
74 GCH_PS_jvmti_oops_do,
75 GCH_PS_CodeCache_oops_do,
76 GCH_PS_younger_gens,
77 // Leave this one last.
78 GCH_PS_NumElements
79 };
80
81 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
82 CollectedHeap(),
83 _rem_set(NULL),
84 _gen_policy(policy),
85 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
86 _full_collections_completed(0)
87 {
88 assert(policy != NULL, "Sanity check");
89 if (UseConcMarkSweepGC) {
90 _workers = new WorkGang("GC Thread", ParallelGCThreads,
91 /* are_GC_task_threads */true,
92 /* are_ConcurrentGC_threads */false);
93 _workers->initialize_workers();
94 } else {
95 // Serial GC does not use workers.
96 _workers = NULL;
97 }
98 }
99
100 jint GenCollectedHeap::initialize() {
101 CollectedHeap::pre_initialize();
102
103 // While there are no constraints in the GC code that HeapWordSize
104 // be any particular value, there are multiple other areas in the
105 // system which believe this to be true (e.g. oop->object_size in some
106 // cases incorrectly returns the size in wordSize units rather than
107 // HeapWordSize).
108 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
109
110 // Allocate space for the heap.
111
112 char* heap_address;
113 ReservedSpace heap_rs;
114
115 size_t heap_alignment = collector_policy()->heap_alignment();
116
117 heap_address = allocate(heap_alignment, &heap_rs);
118
119 if (!heap_rs.is_reserved()) {
120 vm_shutdown_during_initialization(
121 "Could not reserve enough space for object heap");
122 return JNI_ENOMEM;
123 }
124
125 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
126
127 _rem_set = collector_policy()->create_rem_set(reserved_region());
128 set_barrier_set(rem_set()->bs());
129
130 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
131 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set());
132 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
133
134 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
135 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set());
136 clear_incremental_collection_failed();
137
138 #if INCLUDE_ALL_GCS
139 // If we are running CMS, create the collector responsible
140 // for collecting the CMS generations.
141 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
142 bool success = create_cms_collector();
143 if (!success) return JNI_ENOMEM;
144 }
145 #endif // INCLUDE_ALL_GCS
146
147 return JNI_OK;
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 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
157 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
158
159 // Check for overflow.
160 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
161 if (total_reserved < young_spec->max_size()) {
162 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
163 "the maximum representable size");
164 }
165 assert(total_reserved % alignment == 0,
166 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
167 SIZE_FORMAT, total_reserved, alignment);
168
169 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
170 return heap_rs->base();
171 }
172
173 void GenCollectedHeap::post_initialize() {
174 CollectedHeap::post_initialize();
175 ref_processing_init();
176 assert((_young_gen->kind() == Generation::DefNew) ||
177 (_young_gen->kind() == Generation::ParNew),
178 "Wrong youngest generation type");
179 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
180
181 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
182 _old_gen->kind() == Generation::MarkSweepCompact,
183 "Wrong generation kind");
184
185 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
186 _old_gen->capacity(),
187 def_new_gen->from()->capacity());
188 _gen_policy->initialize_gc_policy_counters();
189 }
190
191 void GenCollectedHeap::ref_processing_init() {
192 _young_gen->ref_processor_init();
193 _old_gen->ref_processor_init();
194 }
195
196 size_t GenCollectedHeap::capacity() const {
197 return _young_gen->capacity() + _old_gen->capacity();
198 }
199
200 size_t GenCollectedHeap::used() const {
201 return _young_gen->used() + _old_gen->used();
202 }
203
204 void GenCollectedHeap::save_used_regions() {
205 _old_gen->save_used_region();
206 _young_gen->save_used_region();
207 }
208
209 size_t GenCollectedHeap::max_capacity() const {
210 return _young_gen->max_capacity() + _old_gen->max_capacity();
211 }
212
213 // Update the _full_collections_completed counter
214 // at the end of a stop-world full GC.
215 unsigned int GenCollectedHeap::update_full_collections_completed() {
216 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
217 assert(_full_collections_completed <= _total_full_collections,
218 "Can't complete more collections than were started");
219 _full_collections_completed = _total_full_collections;
220 ml.notify_all();
221 return _full_collections_completed;
222 }
223
224 // Update the _full_collections_completed counter, as appropriate,
225 // at the end of a concurrent GC cycle. Note the conditional update
226 // below to allow this method to be called by a concurrent collector
227 // without synchronizing in any manner with the VM thread (which
228 // may already have initiated a STW full collection "concurrently").
229 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
230 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
231 assert((_full_collections_completed <= _total_full_collections) &&
232 (count <= _total_full_collections),
233 "Can't complete more collections than were started");
234 if (count > _full_collections_completed) {
235 _full_collections_completed = count;
236 ml.notify_all();
237 }
238 return _full_collections_completed;
239 }
240
241
242 #ifndef PRODUCT
243 // Override of memory state checking method in CollectedHeap:
244 // Some collectors (CMS for example) can't have badHeapWordVal written
245 // in the first two words of an object. (For instance , in the case of
246 // CMS these words hold state used to synchronize between certain
247 // (concurrent) GC steps and direct allocating mutators.)
248 // The skip_header_HeapWords() method below, allows us to skip
249 // over the requisite number of HeapWord's. Note that (for
250 // generational collectors) this means that those many words are
251 // skipped in each object, irrespective of the generation in which
252 // that object lives. The resultant loss of precision seems to be
253 // harmless and the pain of avoiding that imprecision appears somewhat
254 // higher than we are prepared to pay for such rudimentary debugging
255 // support.
256 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
257 size_t size) {
258 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
259 // We are asked to check a size in HeapWords,
260 // but the memory is mangled in juint words.
261 juint* start = (juint*) (addr + skip_header_HeapWords());
262 juint* end = (juint*) (addr + size);
263 for (juint* slot = start; slot < end; slot += 1) {
264 assert(*slot == badHeapWordVal,
265 "Found non badHeapWordValue in pre-allocation check");
266 }
267 }
268 }
269 #endif
270
271 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
272 bool is_tlab,
273 bool first_only) {
274 HeapWord* res = NULL;
275
276 if (_young_gen->should_allocate(size, is_tlab)) {
277 res = _young_gen->allocate(size, is_tlab);
278 if (res != NULL || first_only) {
279 return res;
280 }
281 }
282
283 if (_old_gen->should_allocate(size, is_tlab)) {
284 res = _old_gen->allocate(size, is_tlab);
285 }
286
287 return res;
288 }
289
290 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
291 bool* gc_overhead_limit_was_exceeded) {
292 return gen_policy()->mem_allocate_work(size,
293 false /* is_tlab */,
294 gc_overhead_limit_was_exceeded);
295 }
296
297 bool GenCollectedHeap::must_clear_all_soft_refs() {
298 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
299 _gc_cause == GCCause::_wb_full_gc;
300 }
301
302 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
303 if (!UseConcMarkSweepGC) {
304 return false;
305 }
306
307 switch (cause) {
308 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
309 case GCCause::_java_lang_system_gc:
310 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
311 default: return false;
312 }
313 }
314
315 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
316 bool is_tlab, bool run_verification, bool clear_soft_refs,
317 bool restore_marks_for_biased_locking) {
318 FormatBuffer<> title("Collect gen: %s", gen->short_name());
319 GCTraceTime(Trace, gc, phases) t1(title);
320 TraceCollectorStats tcs(gen->counters());
321 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
322
323 gen->stat_record()->invocations++;
324 gen->stat_record()->accumulated_time.start();
325
326 // Must be done anew before each collection because
327 // a previous collection will do mangling and will
328 // change top of some spaces.
329 record_gen_tops_before_GC();
330
331 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
332
333 if (run_verification && VerifyBeforeGC) {
334 HandleMark hm; // Discard invalid handles created during verification
335 Universe::verify("Before GC");
336 }
337 COMPILER2_PRESENT(DerivedPointerTable::clear());
338
339 if (restore_marks_for_biased_locking) {
340 // We perform this mark word preservation work lazily
341 // because it's only at this point that we know whether we
342 // absolutely have to do it; we want to avoid doing it for
343 // scavenge-only collections where it's unnecessary
344 BiasedLocking::preserve_marks();
345 }
346
347 // Do collection work
348 {
349 // Note on ref discovery: For what appear to be historical reasons,
350 // GCH enables and disabled (by enqueing) refs discovery.
351 // In the future this should be moved into the generation's
352 // collect method so that ref discovery and enqueueing concerns
353 // are local to a generation. The collect method could return
354 // an appropriate indication in the case that notification on
355 // the ref lock was needed. This will make the treatment of
356 // weak refs more uniform (and indeed remove such concerns
357 // from GCH). XXX
358
359 HandleMark hm; // Discard invalid handles created during gc
360 save_marks(); // save marks for all gens
361 // We want to discover references, but not process them yet.
362 // This mode is disabled in process_discovered_references if the
363 // generation does some collection work, or in
364 // enqueue_discovered_references if the generation returns
365 // without doing any work.
366 ReferenceProcessor* rp = gen->ref_processor();
367 // If the discovery of ("weak") refs in this generation is
368 // atomic wrt other collectors in this configuration, we
369 // are guaranteed to have empty discovered ref lists.
370 if (rp->discovery_is_atomic()) {
371 rp->enable_discovery();
372 rp->setup_policy(clear_soft_refs);
373 } else {
374 // collect() below will enable discovery as appropriate
375 }
376 gen->collect(full, clear_soft_refs, size, is_tlab);
377 if (!rp->enqueuing_is_done()) {
378 rp->enqueue_discovered_references();
379 } else {
380 rp->set_enqueuing_is_done(false);
381 }
382 rp->verify_no_references_recorded();
383 }
384
385 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
386
387 gen->stat_record()->accumulated_time.stop();
388
389 update_gc_stats(gen, full);
390
391 if (run_verification && VerifyAfterGC) {
392 HandleMark hm; // Discard invalid handles created during verification
393 Universe::verify("After GC");
394 }
395 }
396
397 void GenCollectedHeap::do_collection(bool full,
398 bool clear_all_soft_refs,
399 size_t size,
400 bool is_tlab,
401 GenerationType max_generation) {
402 ResourceMark rm;
403 DEBUG_ONLY(Thread* my_thread = Thread::current();)
404
405 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
406 assert(my_thread->is_VM_thread() ||
407 my_thread->is_ConcurrentGC_thread(),
408 "incorrect thread type capability");
409 assert(Heap_lock->is_locked(),
410 "the requesting thread should have the Heap_lock");
411 guarantee(!is_gc_active(), "collection is not reentrant");
412
413 if (GCLocker::check_active_before_gc()) {
414 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
415 }
416
417 GCIdMarkAndRestore gc_id_mark;
418
419 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
420 collector_policy()->should_clear_all_soft_refs();
421
422 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
423
424 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
425
426 print_heap_before_gc();
427
428 {
429 FlagSetting fl(_is_gc_active, true);
430
431 bool complete = full && (max_generation == OldGen);
432 bool old_collects_young = complete && !ScavengeBeforeFullGC;
433 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
434
435 FormatBuffer<> gc_string("%s", "Pause ");
436 if (do_young_collection) {
437 gc_string.append("Young");
438 } else {
439 gc_string.append("Full");
440 }
441
442 GCTraceCPUTime tcpu;
443 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
444
445 gc_prologue(complete);
446 increment_total_collections(complete);
447
448 size_t young_prev_used = _young_gen->used();
449 size_t old_prev_used = _old_gen->used();
450
451 bool run_verification = total_collections() >= VerifyGCStartAt;
452
453 bool prepared_for_verification = false;
454 bool collected_old = false;
455
456 if (do_young_collection) {
457 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
458 prepare_for_verify();
459 prepared_for_verification = true;
460 }
461
462 collect_generation(_young_gen,
463 full,
464 size,
465 is_tlab,
466 run_verification && VerifyGCLevel <= 0,
467 do_clear_all_soft_refs,
468 false);
469
470 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
471 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
472 // Allocation request was met by young GC.
473 size = 0;
474 }
475 }
476
477 bool must_restore_marks_for_biased_locking = false;
478
479 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
480 if (!complete) {
481 // The full_collections increment was missed above.
482 increment_total_full_collections();
483 }
484
485 if (!prepared_for_verification && run_verification &&
486 VerifyGCLevel <= 1 && VerifyBeforeGC) {
487 prepare_for_verify();
488 }
489
490 if (do_young_collection) {
491 // We did a young GC. Need a new GC id for the old GC.
492 GCIdMarkAndRestore gc_id_mark;
493 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
494 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
495 } else {
496 // No young GC done. Use the same GC id as was set up earlier in this method.
497 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
498 }
499
500 must_restore_marks_for_biased_locking = true;
501 collected_old = true;
502 }
503
504 // Update "complete" boolean wrt what actually transpired --
505 // for instance, a promotion failure could have led to
506 // a whole heap collection.
507 complete = complete || collected_old;
508
509 print_heap_change(young_prev_used, old_prev_used);
510 MetaspaceAux::print_metaspace_change(metadata_prev_used);
511
512 // Adjust generation sizes.
513 if (collected_old) {
514 _old_gen->compute_new_size();
515 }
516 _young_gen->compute_new_size();
517
518 if (complete) {
519 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
520 ClassLoaderDataGraph::purge();
521 MetaspaceAux::verify_metrics();
522 // Resize the metaspace capacity after full collections
523 MetaspaceGC::compute_new_size();
524 update_full_collections_completed();
525 }
526
527 // Track memory usage and detect low memory after GC finishes
528 MemoryService::track_memory_usage();
529
530 gc_epilogue(complete);
531
532 if (must_restore_marks_for_biased_locking) {
533 BiasedLocking::restore_marks();
534 }
535 }
536
537 print_heap_after_gc();
538
539 #ifdef TRACESPINNING
540 ParallelTaskTerminator::print_termination_counts();
541 #endif
542 }
543
544 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
545 return gen_policy()->satisfy_failed_allocation(size, is_tlab);
546 }
547
548 #ifdef ASSERT
549 class AssertNonScavengableClosure: public OopClosure {
550 public:
551 virtual void do_oop(oop* p) {
552 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
553 "Referent should not be scavengable."); }
554 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
555 };
556 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
557 #endif
558
559 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
560 ScanningOption so,
561 OopClosure* strong_roots,
562 OopClosure* weak_roots,
563 CLDClosure* strong_cld_closure,
564 CLDClosure* weak_cld_closure,
565 CodeBlobToOopClosure* code_roots) {
566 // General roots.
567 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
568 assert(code_roots != NULL, "code root closure should always be set");
569 // _n_termination for _process_strong_tasks should be set up stream
570 // in a method not running in a GC worker. Otherwise the GC worker
571 // could be trying to change the termination condition while the task
572 // is executing in another GC worker.
573
574 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
575 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
576 }
577
578 // Some CLDs contained in the thread frames should be considered strong.
579 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
580 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
581 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
582 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
583
584 bool is_par = scope->n_threads() > 1;
585 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
586
587 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
588 Universe::oops_do(strong_roots);
589 }
590 // Global (strong) JNI handles
591 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
592 JNIHandles::oops_do(strong_roots);
593 }
594
595 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
596 ObjectSynchronizer::oops_do(strong_roots);
597 }
598 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
599 FlatProfiler::oops_do(strong_roots);
600 }
601 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
602 Management::oops_do(strong_roots);
603 }
604 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
605 JvmtiExport::oops_do(strong_roots);
606 }
607
608 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
609 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
610 }
611
612 // All threads execute the following. A specific chunk of buckets
613 // from the StringTable are the individual tasks.
614 if (weak_roots != NULL) {
615 if (is_par) {
616 StringTable::possibly_parallel_oops_do(weak_roots);
617 } else {
618 StringTable::oops_do(weak_roots);
619 }
620 }
621
622 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
623 if (so & SO_ScavengeCodeCache) {
624 assert(code_roots != NULL, "must supply closure for code cache");
625
626 // We only visit parts of the CodeCache when scavenging.
627 CodeCache::scavenge_root_nmethods_do(code_roots);
628 }
629 if (so & SO_AllCodeCache) {
630 assert(code_roots != NULL, "must supply closure for code cache");
631
632 // CMSCollector uses this to do intermediate-strength collections.
633 // We scan the entire code cache, since CodeCache::do_unloading is not called.
634 CodeCache::blobs_do(code_roots);
635 }
636 // Verify that the code cache contents are not subject to
637 // movement by a scavenging collection.
638 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
639 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
640 }
641 }
642
643 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope,
644 GenerationType type,
645 bool young_gen_as_roots,
646 ScanningOption so,
647 bool only_strong_roots,
648 OopsInGenClosure* not_older_gens,
649 OopsInGenClosure* older_gens,
650 CLDClosure* cld_closure) {
651 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots;
652
653 bool is_moving_collection = false;
654 if (type == YoungGen || is_adjust_phase) {
655 // young collections are always moving
656 is_moving_collection = true;
657 }
658
659 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
660 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
661 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
662
663 process_roots(scope, so,
664 not_older_gens, weak_roots,
665 cld_closure, weak_cld_closure,
666 &mark_code_closure);
667
668 if (young_gen_as_roots) {
669 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
670 if (type == OldGen) {
671 not_older_gens->set_generation(_young_gen);
672 _young_gen->oop_iterate(not_older_gens);
673 }
674 not_older_gens->reset_generation();
675 }
676 }
677 // When collection is parallel, all threads get to cooperate to do
678 // old generation scanning.
679 if (type == YoungGen) {
680 older_gens->set_generation(_old_gen);
681 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
682 older_gens->reset_generation();
683 }
684
685 _process_strong_tasks->all_tasks_completed(scope->n_threads());
686 }
687
688 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
689 JNIHandles::weak_oops_do(root_closure);
690 _young_gen->ref_processor()->weak_oops_do(root_closure);
691 _old_gen->ref_processor()->weak_oops_do(root_closure);
692 }
693
694 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
695 void GenCollectedHeap:: \
696 oop_since_save_marks_iterate(GenerationType gen, \
697 OopClosureType* cur, \
698 OopClosureType* older) { \
699 if (gen == YoungGen) { \
700 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
701 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
702 } else { \
703 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
704 } \
705 }
706
707 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
708
709 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
710
711 bool GenCollectedHeap::no_allocs_since_save_marks() {
712 return _young_gen->no_allocs_since_save_marks() &&
713 _old_gen->no_allocs_since_save_marks();
714 }
715
716 bool GenCollectedHeap::supports_inline_contig_alloc() const {
717 return _young_gen->supports_inline_contig_alloc();
718 }
719
720 HeapWord** GenCollectedHeap::top_addr() const {
721 return _young_gen->top_addr();
722 }
723
724 HeapWord** GenCollectedHeap::end_addr() const {
725 return _young_gen->end_addr();
726 }
727
728 // public collection interfaces
729
730 void GenCollectedHeap::collect(GCCause::Cause cause) {
731 if (should_do_concurrent_full_gc(cause)) {
732 #if INCLUDE_ALL_GCS
733 // Mostly concurrent full collection.
734 collect_mostly_concurrent(cause);
735 #else // INCLUDE_ALL_GCS
736 ShouldNotReachHere();
737 #endif // INCLUDE_ALL_GCS
738 } else if (cause == GCCause::_wb_young_gc) {
739 // Young collection for the WhiteBox API.
740 collect(cause, YoungGen);
741 } else {
742 #ifdef ASSERT
743 if (cause == GCCause::_scavenge_alot) {
744 // Young collection only.
745 collect(cause, YoungGen);
746 } else {
747 // Stop-the-world full collection.
748 collect(cause, OldGen);
749 }
750 #else
751 // Stop-the-world full collection.
752 collect(cause, OldGen);
753 #endif
754 }
755 }
756
757 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
758 // The caller doesn't have the Heap_lock
759 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
760 MutexLocker ml(Heap_lock);
761 collect_locked(cause, max_generation);
762 }
763
764 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
765 // The caller has the Heap_lock
766 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
767 collect_locked(cause, OldGen);
768 }
769
770 // this is the private collection interface
771 // The Heap_lock is expected to be held on entry.
772
773 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
774 // Read the GC count while holding the Heap_lock
775 unsigned int gc_count_before = total_collections();
776 unsigned int full_gc_count_before = total_full_collections();
777 {
778 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
779 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
780 cause, max_generation);
781 VMThread::execute(&op);
782 }
783 }
784
785 #if INCLUDE_ALL_GCS
786 bool GenCollectedHeap::create_cms_collector() {
787
788 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
789 "Unexpected generation kinds");
790 // Skip two header words in the block content verification
791 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
792 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type");
793 CMSCollector* collector =
794 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen,
795 _rem_set,
796 _gen_policy->as_concurrent_mark_sweep_policy());
797
798 if (collector == NULL || !collector->completed_initialization()) {
799 if (collector) {
800 delete collector; // Be nice in embedded situation
801 }
802 vm_shutdown_during_initialization("Could not create CMS collector");
803 return false;
804 }
805 return true; // success
806 }
807
808 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
809 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
810
811 MutexLocker ml(Heap_lock);
812 // Read the GC counts while holding the Heap_lock
813 unsigned int full_gc_count_before = total_full_collections();
814 unsigned int gc_count_before = total_collections();
815 {
816 MutexUnlocker mu(Heap_lock);
817 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
818 VMThread::execute(&op);
819 }
820 }
821 #endif // INCLUDE_ALL_GCS
822
823 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
824 do_full_collection(clear_all_soft_refs, OldGen);
825 }
826
827 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
828 GenerationType last_generation) {
829 GenerationType local_last_generation;
830 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
831 gc_cause() == GCCause::_gc_locker) {
832 local_last_generation = YoungGen;
833 } else {
834 local_last_generation = last_generation;
835 }
836
837 do_collection(true, // full
838 clear_all_soft_refs, // clear_all_soft_refs
839 0, // size
840 false, // is_tlab
841 local_last_generation); // last_generation
842 // Hack XXX FIX ME !!!
843 // A scavenge may not have been attempted, or may have
844 // been attempted and failed, because the old gen was too full
845 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
846 incremental_collection_will_fail(false /* don't consult_young */)) {
847 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
848 // This time allow the old gen to be collected as well
849 do_collection(true, // full
850 clear_all_soft_refs, // clear_all_soft_refs
851 0, // size
852 false, // is_tlab
853 OldGen); // last_generation
854 }
855 }
856
857 bool GenCollectedHeap::is_in_young(oop p) {
858 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
859 assert(result == _young_gen->is_in_reserved(p),
860 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
861 return result;
862 }
863
864 // Returns "TRUE" iff "p" points into the committed areas of the heap.
865 bool GenCollectedHeap::is_in(const void* p) const {
866 return _young_gen->is_in(p) || _old_gen->is_in(p);
867 }
868
869 #ifdef ASSERT
870 // Don't implement this by using is_in_young(). This method is used
871 // in some cases to check that is_in_young() is correct.
872 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
873 assert(is_in_reserved(p) || p == NULL,
874 "Does not work if address is non-null and outside of the heap");
875 return p < _young_gen->reserved().end() && p != NULL;
876 }
877 #endif
878
879 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
880 NoHeaderExtendedOopClosure no_header_cl(cl);
881 oop_iterate(&no_header_cl);
882 }
883
884 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
885 _young_gen->oop_iterate(cl);
886 _old_gen->oop_iterate(cl);
887 }
888
889 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
890 _young_gen->object_iterate(cl);
891 _old_gen->object_iterate(cl);
892 }
893
894 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
895 _young_gen->safe_object_iterate(cl);
896 _old_gen->safe_object_iterate(cl);
897 }
898
899 Space* GenCollectedHeap::space_containing(const void* addr) const {
900 Space* res = _young_gen->space_containing(addr);
901 if (res != NULL) {
902 return res;
903 }
904 res = _old_gen->space_containing(addr);
905 assert(res != NULL, "Could not find containing space");
906 return res;
907 }
908
909 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
910 assert(is_in_reserved(addr), "block_start of address outside of heap");
911 if (_young_gen->is_in_reserved(addr)) {
912 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
913 return _young_gen->block_start(addr);
914 }
915
916 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
917 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
918 return _old_gen->block_start(addr);
919 }
920
921 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
922 assert(is_in_reserved(addr), "block_size of address outside of heap");
923 if (_young_gen->is_in_reserved(addr)) {
924 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
925 return _young_gen->block_size(addr);
926 }
927
928 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
929 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
930 return _old_gen->block_size(addr);
931 }
932
933 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
934 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
935 assert(block_start(addr) == addr, "addr must be a block start");
936 if (_young_gen->is_in_reserved(addr)) {
937 return _young_gen->block_is_obj(addr);
938 }
939
940 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
941 return _old_gen->block_is_obj(addr);
942 }
943
944 bool GenCollectedHeap::supports_tlab_allocation() const {
945 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
946 return _young_gen->supports_tlab_allocation();
947 }
948
949 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
950 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
951 if (_young_gen->supports_tlab_allocation()) {
952 return _young_gen->tlab_capacity();
953 }
954 return 0;
955 }
956
957 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
958 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
959 if (_young_gen->supports_tlab_allocation()) {
960 return _young_gen->tlab_used();
961 }
962 return 0;
963 }
964
965 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
966 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
967 if (_young_gen->supports_tlab_allocation()) {
968 return _young_gen->unsafe_max_tlab_alloc();
969 }
970 return 0;
971 }
972
973 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
974 bool gc_overhead_limit_was_exceeded;
975 return gen_policy()->mem_allocate_work(size /* size */,
976 true /* is_tlab */,
977 &gc_overhead_limit_was_exceeded);
978 }
979
980 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
981 // from the list headed by "*prev_ptr".
982 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
983 bool first = true;
984 size_t min_size = 0; // "first" makes this conceptually infinite.
985 ScratchBlock **smallest_ptr, *smallest;
986 ScratchBlock *cur = *prev_ptr;
987 while (cur) {
988 assert(*prev_ptr == cur, "just checking");
989 if (first || cur->num_words < min_size) {
990 smallest_ptr = prev_ptr;
991 smallest = cur;
992 min_size = smallest->num_words;
993 first = false;
994 }
995 prev_ptr = &cur->next;
996 cur = cur->next;
997 }
998 smallest = *smallest_ptr;
999 *smallest_ptr = smallest->next;
1000 return smallest;
1001 }
1002
1003 // Sort the scratch block list headed by res into decreasing size order,
1004 // and set "res" to the result.
1005 static void sort_scratch_list(ScratchBlock*& list) {
1006 ScratchBlock* sorted = NULL;
1007 ScratchBlock* unsorted = list;
1008 while (unsorted) {
1009 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1010 smallest->next = sorted;
1011 sorted = smallest;
1012 }
1013 list = sorted;
1014 }
1015
1016 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1017 size_t max_alloc_words) {
1018 ScratchBlock* res = NULL;
1019 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1020 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1021 sort_scratch_list(res);
1022 return res;
1023 }
1024
1025 void GenCollectedHeap::release_scratch() {
1026 _young_gen->reset_scratch();
1027 _old_gen->reset_scratch();
1028 }
1029
1030 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1031 void do_generation(Generation* gen) {
1032 gen->prepare_for_verify();
1033 }
1034 };
1035
1036 void GenCollectedHeap::prepare_for_verify() {
1037 ensure_parsability(false); // no need to retire TLABs
1038 GenPrepareForVerifyClosure blk;
1039 generation_iterate(&blk, false);
1040 }
1041
1042 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1043 bool old_to_young) {
1044 if (old_to_young) {
1045 cl->do_generation(_old_gen);
1046 cl->do_generation(_young_gen);
1047 } else {
1048 cl->do_generation(_young_gen);
1049 cl->do_generation(_old_gen);
1050 }
1051 }
1052
1053 bool GenCollectedHeap::is_maximal_no_gc() const {
1054 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1055 }
1056
1057 void GenCollectedHeap::save_marks() {
1058 _young_gen->save_marks();
1059 _old_gen->save_marks();
1060 }
1061
1062 GenCollectedHeap* GenCollectedHeap::heap() {
1063 CollectedHeap* heap = Universe::heap();
1064 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1065 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
1066 return (GenCollectedHeap*)heap;
1067 }
1068
1069 void GenCollectedHeap::prepare_for_compaction() {
1070 // Start by compacting into same gen.
1071 CompactPoint cp(_old_gen);
1072 _old_gen->prepare_for_compaction(&cp);
1073 _young_gen->prepare_for_compaction(&cp);
1074 }
1075
1076 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1077 log_debug(gc, verify)("%s", _old_gen->name());
1078 _old_gen->verify();
1079
1080 log_debug(gc, verify)("%s", _old_gen->name());
1081 _young_gen->verify();
1082
1083 log_debug(gc, verify)("RemSet");
1084 rem_set()->verify();
1085 }
1086
1087 void GenCollectedHeap::print_on(outputStream* st) const {
1088 _young_gen->print_on(st);
1089 _old_gen->print_on(st);
1090 MetaspaceAux::print_on(st);
1091 }
1092
1093 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1094 if (workers() != NULL) {
1095 workers()->threads_do(tc);
1096 }
1097 #if INCLUDE_ALL_GCS
1098 if (UseConcMarkSweepGC) {
1099 ConcurrentMarkSweepThread::threads_do(tc);
1100 }
1101 #endif // INCLUDE_ALL_GCS
1102 }
1103
1104 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1105 #if INCLUDE_ALL_GCS
1106 if (UseConcMarkSweepGC) {
1107 workers()->print_worker_threads_on(st);
1108 ConcurrentMarkSweepThread::print_all_on(st);
1109 }
1110 #endif // INCLUDE_ALL_GCS
1111 }
1112
1113 void GenCollectedHeap::print_on_error(outputStream* st) const {
1114 this->CollectedHeap::print_on_error(st);
1115
1116 #if INCLUDE_ALL_GCS
1117 if (UseConcMarkSweepGC) {
1118 st->cr();
1119 CMSCollector::print_on_error(st);
1120 }
1121 #endif // INCLUDE_ALL_GCS
1122 }
1123
1124 void GenCollectedHeap::print_tracing_info() const {
1125 if (TraceYoungGenTime) {
1126 _young_gen->print_summary_info();
1127 }
1128 if (TraceOldGenTime) {
1129 _old_gen->print_summary_info();
1130 }
1131 }
1132
1133 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1134 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1135 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1136 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1137 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1138 }
1139
1140 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1141 private:
1142 bool _full;
1143 public:
1144 void do_generation(Generation* gen) {
1145 gen->gc_prologue(_full);
1146 }
1147 GenGCPrologueClosure(bool full) : _full(full) {};
1148 };
1149
1150 void GenCollectedHeap::gc_prologue(bool full) {
1151 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1152
1153 always_do_update_barrier = false;
1154 // Fill TLAB's and such
1155 CollectedHeap::accumulate_statistics_all_tlabs();
1156 ensure_parsability(true); // retire TLABs
1157
1158 // Walk generations
1159 GenGCPrologueClosure blk(full);
1160 generation_iterate(&blk, false); // not old-to-young.
1161 };
1162
1163 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1164 private:
1165 bool _full;
1166 public:
1167 void do_generation(Generation* gen) {
1168 gen->gc_epilogue(_full);
1169 }
1170 GenGCEpilogueClosure(bool full) : _full(full) {};
1171 };
1172
1173 void GenCollectedHeap::gc_epilogue(bool full) {
1174 #if defined(COMPILER2) || INCLUDE_JVMCI
1175 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1176 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1177 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1178 #endif /* COMPILER2 || INCLUDE_JVMCI */
1179
1180 resize_all_tlabs();
1181
1182 GenGCEpilogueClosure blk(full);
1183 generation_iterate(&blk, false); // not old-to-young.
1184
1185 if (!CleanChunkPoolAsync) {
1186 Chunk::clean_chunk_pool();
1187 }
1188
1189 MetaspaceCounters::update_performance_counters();
1190 CompressedClassSpaceCounters::update_performance_counters();
1191
1192 always_do_update_barrier = UseConcMarkSweepGC;
1193 };
1194
1195 #ifndef PRODUCT
1196 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1197 private:
1198 public:
1199 void do_generation(Generation* gen) {
1200 gen->record_spaces_top();
1201 }
1202 };
1203
1204 void GenCollectedHeap::record_gen_tops_before_GC() {
1205 if (ZapUnusedHeapArea) {
1206 GenGCSaveTopsBeforeGCClosure blk;
1207 generation_iterate(&blk, false); // not old-to-young.
1208 }
1209 }
1210 #endif // not PRODUCT
1211
1212 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1213 public:
1214 void do_generation(Generation* gen) {
1215 gen->ensure_parsability();
1216 }
1217 };
1218
1219 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1220 CollectedHeap::ensure_parsability(retire_tlabs);
1221 GenEnsureParsabilityClosure ep_cl;
1222 generation_iterate(&ep_cl, false);
1223 }
1224
1225 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1226 oop obj,
1227 size_t obj_size) {
1228 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1229 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1230 HeapWord* result = NULL;
1231
1232 result = old_gen->expand_and_allocate(obj_size, false);
1233
1234 if (result != NULL) {
1235 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1236 }
1237 return oop(result);
1238 }
1239
1240 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1241 jlong _time; // in ms
1242 jlong _now; // in ms
1243
1244 public:
1245 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1246
1247 jlong time() { return _time; }
1248
1249 void do_generation(Generation* gen) {
1250 _time = MIN2(_time, gen->time_of_last_gc(_now));
1251 }
1252 };
1253
1254 jlong GenCollectedHeap::millis_since_last_gc() {
1255 // We need a monotonically non-decreasing time in ms but
1256 // os::javaTimeMillis() does not guarantee monotonicity.
1257 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1258 GenTimeOfLastGCClosure tolgc_cl(now);
1259 // iterate over generations getting the oldest
1260 // time that a generation was collected
1261 generation_iterate(&tolgc_cl, false);
1262
1263 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1264 // provided the underlying platform provides such a time source
1265 // (and it is bug free). So we still have to guard against getting
1266 // back a time later than 'now'.
1267 jlong retVal = now - tolgc_cl.time();
1268 if (retVal < 0) {
1269 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, retVal);)
1270 return 0;
1271 }
1272 return retVal;
1273 }
1274
1275 void GenCollectedHeap::stop() {
1276 #if INCLUDE_ALL_GCS
1277 if (UseConcMarkSweepGC) {
1278 ConcurrentMarkSweepThread::cmst()->stop();
1279 }
1280 #endif
1281 }