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
171 os::trace_page_sizes("Heap",
172 collector_policy()->min_heap_byte_size(),
173 total_reserved,
174 alignment,
175 heap_rs->base(),
176 heap_rs->size());
177
178 return heap_rs->base();
179 }
180
181 void GenCollectedHeap::post_initialize() {
182 CollectedHeap::post_initialize();
183 ref_processing_init();
184 assert((_young_gen->kind() == Generation::DefNew) ||
185 (_young_gen->kind() == Generation::ParNew),
186 "Wrong youngest generation type");
187 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
188
189 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
190 _old_gen->kind() == Generation::MarkSweepCompact,
191 "Wrong generation kind");
192
193 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
194 _old_gen->capacity(),
195 def_new_gen->from()->capacity());
196 _gen_policy->initialize_gc_policy_counters();
197 }
198
199 void GenCollectedHeap::ref_processing_init() {
200 _young_gen->ref_processor_init();
201 _old_gen->ref_processor_init();
202 }
203
204 size_t GenCollectedHeap::capacity() const {
205 return _young_gen->capacity() + _old_gen->capacity();
206 }
207
208 size_t GenCollectedHeap::used() const {
209 return _young_gen->used() + _old_gen->used();
210 }
211
212 void GenCollectedHeap::save_used_regions() {
213 _old_gen->save_used_region();
214 _young_gen->save_used_region();
215 }
216
217 size_t GenCollectedHeap::max_capacity() const {
218 return _young_gen->max_capacity() + _old_gen->max_capacity();
219 }
220
221 // Update the _full_collections_completed counter
222 // at the end of a stop-world full GC.
223 unsigned int GenCollectedHeap::update_full_collections_completed() {
224 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
225 assert(_full_collections_completed <= _total_full_collections,
226 "Can't complete more collections than were started");
227 _full_collections_completed = _total_full_collections;
228 ml.notify_all();
229 return _full_collections_completed;
230 }
231
232 // Update the _full_collections_completed counter, as appropriate,
233 // at the end of a concurrent GC cycle. Note the conditional update
234 // below to allow this method to be called by a concurrent collector
235 // without synchronizing in any manner with the VM thread (which
236 // may already have initiated a STW full collection "concurrently").
237 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
238 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
239 assert((_full_collections_completed <= _total_full_collections) &&
240 (count <= _total_full_collections),
241 "Can't complete more collections than were started");
242 if (count > _full_collections_completed) {
243 _full_collections_completed = count;
244 ml.notify_all();
245 }
246 return _full_collections_completed;
247 }
248
249
250 #ifndef PRODUCT
251 // Override of memory state checking method in CollectedHeap:
252 // Some collectors (CMS for example) can't have badHeapWordVal written
253 // in the first two words of an object. (For instance , in the case of
254 // CMS these words hold state used to synchronize between certain
255 // (concurrent) GC steps and direct allocating mutators.)
256 // The skip_header_HeapWords() method below, allows us to skip
257 // over the requisite number of HeapWord's. Note that (for
258 // generational collectors) this means that those many words are
259 // skipped in each object, irrespective of the generation in which
260 // that object lives. The resultant loss of precision seems to be
261 // harmless and the pain of avoiding that imprecision appears somewhat
262 // higher than we are prepared to pay for such rudimentary debugging
263 // support.
264 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
265 size_t size) {
266 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
267 // We are asked to check a size in HeapWords,
268 // but the memory is mangled in juint words.
269 juint* start = (juint*) (addr + skip_header_HeapWords());
270 juint* end = (juint*) (addr + size);
271 for (juint* slot = start; slot < end; slot += 1) {
272 assert(*slot == badHeapWordVal,
273 "Found non badHeapWordValue in pre-allocation check");
274 }
275 }
276 }
277 #endif
278
279 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
280 bool is_tlab,
281 bool first_only) {
282 HeapWord* res = NULL;
283
284 if (_young_gen->should_allocate(size, is_tlab)) {
285 res = _young_gen->allocate(size, is_tlab);
286 if (res != NULL || first_only) {
287 return res;
288 }
289 }
290
291 if (_old_gen->should_allocate(size, is_tlab)) {
292 res = _old_gen->allocate(size, is_tlab);
293 }
294
295 return res;
296 }
297
298 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
299 bool* gc_overhead_limit_was_exceeded) {
300 return gen_policy()->mem_allocate_work(size,
301 false /* is_tlab */,
302 gc_overhead_limit_was_exceeded);
303 }
304
305 bool GenCollectedHeap::must_clear_all_soft_refs() {
306 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
307 _gc_cause == GCCause::_wb_full_gc;
308 }
309
310 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
311 if (!UseConcMarkSweepGC) {
312 return false;
313 }
314
315 switch (cause) {
316 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
317 case GCCause::_java_lang_system_gc:
318 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
319 default: return false;
320 }
321 }
322
323 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
324 bool is_tlab, bool run_verification, bool clear_soft_refs,
325 bool restore_marks_for_biased_locking) {
326 FormatBuffer<> title("Collect gen: %s", gen->short_name());
327 GCTraceTime(Trace, gc, phases) t1(title);
328 TraceCollectorStats tcs(gen->counters());
329 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
330
331 gen->stat_record()->invocations++;
332 gen->stat_record()->accumulated_time.start();
333
334 // Must be done anew before each collection because
335 // a previous collection will do mangling and will
336 // change top of some spaces.
337 record_gen_tops_before_GC();
338
339 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
340
341 if (run_verification && VerifyBeforeGC) {
342 HandleMark hm; // Discard invalid handles created during verification
343 Universe::verify("Before GC");
344 }
345 COMPILER2_PRESENT(DerivedPointerTable::clear());
346
347 if (restore_marks_for_biased_locking) {
348 // We perform this mark word preservation work lazily
349 // because it's only at this point that we know whether we
350 // absolutely have to do it; we want to avoid doing it for
351 // scavenge-only collections where it's unnecessary
352 BiasedLocking::preserve_marks();
353 }
354
355 // Do collection work
356 {
357 // Note on ref discovery: For what appear to be historical reasons,
358 // GCH enables and disabled (by enqueing) refs discovery.
359 // In the future this should be moved into the generation's
360 // collect method so that ref discovery and enqueueing concerns
361 // are local to a generation. The collect method could return
362 // an appropriate indication in the case that notification on
363 // the ref lock was needed. This will make the treatment of
364 // weak refs more uniform (and indeed remove such concerns
365 // from GCH). XXX
366
367 HandleMark hm; // Discard invalid handles created during gc
368 save_marks(); // save marks for all gens
369 // We want to discover references, but not process them yet.
370 // This mode is disabled in process_discovered_references if the
371 // generation does some collection work, or in
372 // enqueue_discovered_references if the generation returns
373 // without doing any work.
374 ReferenceProcessor* rp = gen->ref_processor();
375 // If the discovery of ("weak") refs in this generation is
376 // atomic wrt other collectors in this configuration, we
377 // are guaranteed to have empty discovered ref lists.
378 if (rp->discovery_is_atomic()) {
379 rp->enable_discovery();
380 rp->setup_policy(clear_soft_refs);
381 } else {
382 // collect() below will enable discovery as appropriate
383 }
384 gen->collect(full, clear_soft_refs, size, is_tlab);
385 if (!rp->enqueuing_is_done()) {
386 rp->enqueue_discovered_references();
387 } else {
388 rp->set_enqueuing_is_done(false);
389 }
390 rp->verify_no_references_recorded();
391 }
392
393 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
394
395 gen->stat_record()->accumulated_time.stop();
396
397 update_gc_stats(gen, full);
398
399 if (run_verification && VerifyAfterGC) {
400 HandleMark hm; // Discard invalid handles created during verification
401 Universe::verify("After GC");
402 }
403 }
404
405 void GenCollectedHeap::do_collection(bool full,
406 bool clear_all_soft_refs,
407 size_t size,
408 bool is_tlab,
409 GenerationType max_generation) {
410 ResourceMark rm;
411 DEBUG_ONLY(Thread* my_thread = Thread::current();)
412
413 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
414 assert(my_thread->is_VM_thread() ||
415 my_thread->is_ConcurrentGC_thread(),
416 "incorrect thread type capability");
417 assert(Heap_lock->is_locked(),
418 "the requesting thread should have the Heap_lock");
419 guarantee(!is_gc_active(), "collection is not reentrant");
420
421 if (GCLocker::check_active_before_gc()) {
422 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
423 }
424
425 GCIdMarkAndRestore gc_id_mark;
426
427 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
428 collector_policy()->should_clear_all_soft_refs();
429
430 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
431
432 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
433
434 print_heap_before_gc();
435
436 {
437 FlagSetting fl(_is_gc_active, true);
438
439 bool complete = full && (max_generation == OldGen);
440 bool old_collects_young = complete && !ScavengeBeforeFullGC;
441 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
442
443 FormatBuffer<> gc_string("%s", "Pause ");
444 if (do_young_collection) {
445 gc_string.append("Young");
446 } else {
447 gc_string.append("Full");
448 }
449
450 GCTraceCPUTime tcpu;
451 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
452
453 gc_prologue(complete);
454 increment_total_collections(complete);
455
456 size_t young_prev_used = _young_gen->used();
457 size_t old_prev_used = _old_gen->used();
458
459 bool run_verification = total_collections() >= VerifyGCStartAt;
460
461 bool prepared_for_verification = false;
462 bool collected_old = false;
463
464 if (do_young_collection) {
465 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
466 prepare_for_verify();
467 prepared_for_verification = true;
468 }
469
470 collect_generation(_young_gen,
471 full,
472 size,
473 is_tlab,
474 run_verification && VerifyGCLevel <= 0,
475 do_clear_all_soft_refs,
476 false);
477
478 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
479 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
480 // Allocation request was met by young GC.
481 size = 0;
482 }
483 }
484
485 bool must_restore_marks_for_biased_locking = false;
486
487 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
488 if (!complete) {
489 // The full_collections increment was missed above.
490 increment_total_full_collections();
491 }
492
493 if (!prepared_for_verification && run_verification &&
494 VerifyGCLevel <= 1 && VerifyBeforeGC) {
495 prepare_for_verify();
496 }
497
498 if (do_young_collection) {
499 // We did a young GC. Need a new GC id for the old GC.
500 GCIdMarkAndRestore gc_id_mark;
501 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
502 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
503 } else {
504 // No young GC done. Use the same GC id as was set up earlier in this method.
505 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
506 }
507
508 must_restore_marks_for_biased_locking = true;
509 collected_old = true;
510 }
511
512 // Update "complete" boolean wrt what actually transpired --
513 // for instance, a promotion failure could have led to
514 // a whole heap collection.
515 complete = complete || collected_old;
516
517 print_heap_change(young_prev_used, old_prev_used);
518 MetaspaceAux::print_metaspace_change(metadata_prev_used);
519
520 // Adjust generation sizes.
521 if (collected_old) {
522 _old_gen->compute_new_size();
523 }
524 _young_gen->compute_new_size();
525
526 if (complete) {
527 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
528 ClassLoaderDataGraph::purge();
529 MetaspaceAux::verify_metrics();
530 // Resize the metaspace capacity after full collections
531 MetaspaceGC::compute_new_size();
532 update_full_collections_completed();
533 }
534
535 // Track memory usage and detect low memory after GC finishes
536 MemoryService::track_memory_usage();
537
538 gc_epilogue(complete);
539
540 if (must_restore_marks_for_biased_locking) {
541 BiasedLocking::restore_marks();
542 }
543 }
544
545 print_heap_after_gc();
546
547 #ifdef TRACESPINNING
548 ParallelTaskTerminator::print_termination_counts();
549 #endif
550 }
551
552 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
553 return gen_policy()->satisfy_failed_allocation(size, is_tlab);
554 }
555
556 #ifdef ASSERT
557 class AssertNonScavengableClosure: public OopClosure {
558 public:
559 virtual void do_oop(oop* p) {
560 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
561 "Referent should not be scavengable."); }
562 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
563 };
564 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
565 #endif
566
567 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
568 ScanningOption so,
569 OopClosure* strong_roots,
570 OopClosure* weak_roots,
571 CLDClosure* strong_cld_closure,
572 CLDClosure* weak_cld_closure,
573 CodeBlobToOopClosure* code_roots) {
574 // General roots.
575 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
576 assert(code_roots != NULL, "code root closure should always be set");
577 // _n_termination for _process_strong_tasks should be set up stream
578 // in a method not running in a GC worker. Otherwise the GC worker
579 // could be trying to change the termination condition while the task
580 // is executing in another GC worker.
581
582 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
583 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
584 }
585
586 // Some CLDs contained in the thread frames should be considered strong.
587 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
588 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
589 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
590 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
591
592 bool is_par = scope->n_threads() > 1;
593 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
594
595 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
596 Universe::oops_do(strong_roots);
597 }
598 // Global (strong) JNI handles
599 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
600 JNIHandles::oops_do(strong_roots);
601 }
602
603 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
604 ObjectSynchronizer::oops_do(strong_roots);
605 }
606 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
607 FlatProfiler::oops_do(strong_roots);
608 }
609 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
610 Management::oops_do(strong_roots);
611 }
612 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
613 JvmtiExport::oops_do(strong_roots);
614 }
615
616 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
617 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
618 }
619
620 // All threads execute the following. A specific chunk of buckets
621 // from the StringTable are the individual tasks.
622 if (weak_roots != NULL) {
623 if (is_par) {
624 StringTable::possibly_parallel_oops_do(weak_roots);
625 } else {
626 StringTable::oops_do(weak_roots);
627 }
628 }
629
630 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
631 if (so & SO_ScavengeCodeCache) {
632 assert(code_roots != NULL, "must supply closure for code cache");
633
634 // We only visit parts of the CodeCache when scavenging.
635 CodeCache::scavenge_root_nmethods_do(code_roots);
636 }
637 if (so & SO_AllCodeCache) {
638 assert(code_roots != NULL, "must supply closure for code cache");
639
640 // CMSCollector uses this to do intermediate-strength collections.
641 // We scan the entire code cache, since CodeCache::do_unloading is not called.
642 CodeCache::blobs_do(code_roots);
643 }
644 // Verify that the code cache contents are not subject to
645 // movement by a scavenging collection.
646 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
647 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
648 }
649 }
650
651 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope,
652 GenerationType type,
653 bool young_gen_as_roots,
654 ScanningOption so,
655 bool only_strong_roots,
656 OopsInGenClosure* not_older_gens,
657 OopsInGenClosure* older_gens,
658 CLDClosure* cld_closure) {
659 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots;
660
661 bool is_moving_collection = false;
662 if (type == YoungGen || is_adjust_phase) {
663 // young collections are always moving
664 is_moving_collection = true;
665 }
666
667 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
668 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
669 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
670
671 process_roots(scope, so,
672 not_older_gens, weak_roots,
673 cld_closure, weak_cld_closure,
674 &mark_code_closure);
675
676 if (young_gen_as_roots) {
677 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
678 if (type == OldGen) {
679 not_older_gens->set_generation(_young_gen);
680 _young_gen->oop_iterate(not_older_gens);
681 }
682 not_older_gens->reset_generation();
683 }
684 }
685 // When collection is parallel, all threads get to cooperate to do
686 // old generation scanning.
687 if (type == YoungGen) {
688 older_gens->set_generation(_old_gen);
689 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
690 older_gens->reset_generation();
691 }
692
693 _process_strong_tasks->all_tasks_completed(scope->n_threads());
694 }
695
696 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
697 JNIHandles::weak_oops_do(root_closure);
698 _young_gen->ref_processor()->weak_oops_do(root_closure);
699 _old_gen->ref_processor()->weak_oops_do(root_closure);
700 }
701
702 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
703 void GenCollectedHeap:: \
704 oop_since_save_marks_iterate(GenerationType gen, \
705 OopClosureType* cur, \
706 OopClosureType* older) { \
707 if (gen == YoungGen) { \
708 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
709 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
710 } else { \
711 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
712 } \
713 }
714
715 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
716
717 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
718
719 bool GenCollectedHeap::no_allocs_since_save_marks() {
720 return _young_gen->no_allocs_since_save_marks() &&
721 _old_gen->no_allocs_since_save_marks();
722 }
723
724 bool GenCollectedHeap::supports_inline_contig_alloc() const {
725 return _young_gen->supports_inline_contig_alloc();
726 }
727
728 HeapWord** GenCollectedHeap::top_addr() const {
729 return _young_gen->top_addr();
730 }
731
732 HeapWord** GenCollectedHeap::end_addr() const {
733 return _young_gen->end_addr();
734 }
735
736 // public collection interfaces
737
738 void GenCollectedHeap::collect(GCCause::Cause cause) {
739 if (should_do_concurrent_full_gc(cause)) {
740 #if INCLUDE_ALL_GCS
741 // Mostly concurrent full collection.
742 collect_mostly_concurrent(cause);
743 #else // INCLUDE_ALL_GCS
744 ShouldNotReachHere();
745 #endif // INCLUDE_ALL_GCS
746 } else if (cause == GCCause::_wb_young_gc) {
747 // Young collection for the WhiteBox API.
748 collect(cause, YoungGen);
749 } else {
750 #ifdef ASSERT
751 if (cause == GCCause::_scavenge_alot) {
752 // Young collection only.
753 collect(cause, YoungGen);
754 } else {
755 // Stop-the-world full collection.
756 collect(cause, OldGen);
757 }
758 #else
759 // Stop-the-world full collection.
760 collect(cause, OldGen);
761 #endif
762 }
763 }
764
765 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
766 // The caller doesn't have the Heap_lock
767 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
768 MutexLocker ml(Heap_lock);
769 collect_locked(cause, max_generation);
770 }
771
772 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
773 // The caller has the Heap_lock
774 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
775 collect_locked(cause, OldGen);
776 }
777
778 // this is the private collection interface
779 // The Heap_lock is expected to be held on entry.
780
781 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
782 // Read the GC count while holding the Heap_lock
783 unsigned int gc_count_before = total_collections();
784 unsigned int full_gc_count_before = total_full_collections();
785 {
786 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
787 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
788 cause, max_generation);
789 VMThread::execute(&op);
790 }
791 }
792
793 #if INCLUDE_ALL_GCS
794 bool GenCollectedHeap::create_cms_collector() {
795
796 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
797 "Unexpected generation kinds");
798 // Skip two header words in the block content verification
799 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
800 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type");
801 CMSCollector* collector =
802 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen,
803 _rem_set,
804 _gen_policy->as_concurrent_mark_sweep_policy());
805
806 if (collector == NULL || !collector->completed_initialization()) {
807 if (collector) {
808 delete collector; // Be nice in embedded situation
809 }
810 vm_shutdown_during_initialization("Could not create CMS collector");
811 return false;
812 }
813 return true; // success
814 }
815
816 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
817 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
818
819 MutexLocker ml(Heap_lock);
820 // Read the GC counts while holding the Heap_lock
821 unsigned int full_gc_count_before = total_full_collections();
822 unsigned int gc_count_before = total_collections();
823 {
824 MutexUnlocker mu(Heap_lock);
825 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
826 VMThread::execute(&op);
827 }
828 }
829 #endif // INCLUDE_ALL_GCS
830
831 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
832 do_full_collection(clear_all_soft_refs, OldGen);
833 }
834
835 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
836 GenerationType last_generation) {
837 GenerationType local_last_generation;
838 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
839 gc_cause() == GCCause::_gc_locker) {
840 local_last_generation = YoungGen;
841 } else {
842 local_last_generation = last_generation;
843 }
844
845 do_collection(true, // full
846 clear_all_soft_refs, // clear_all_soft_refs
847 0, // size
848 false, // is_tlab
849 local_last_generation); // last_generation
850 // Hack XXX FIX ME !!!
851 // A scavenge may not have been attempted, or may have
852 // been attempted and failed, because the old gen was too full
853 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
854 incremental_collection_will_fail(false /* don't consult_young */)) {
855 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
856 // This time allow the old gen to be collected as well
857 do_collection(true, // full
858 clear_all_soft_refs, // clear_all_soft_refs
859 0, // size
860 false, // is_tlab
861 OldGen); // last_generation
862 }
863 }
864
865 bool GenCollectedHeap::is_in_young(oop p) {
866 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
867 assert(result == _young_gen->is_in_reserved(p),
868 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
869 return result;
870 }
871
872 // Returns "TRUE" iff "p" points into the committed areas of the heap.
873 bool GenCollectedHeap::is_in(const void* p) const {
874 return _young_gen->is_in(p) || _old_gen->is_in(p);
875 }
876
877 #ifdef ASSERT
878 // Don't implement this by using is_in_young(). This method is used
879 // in some cases to check that is_in_young() is correct.
880 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
881 assert(is_in_reserved(p) || p == NULL,
882 "Does not work if address is non-null and outside of the heap");
883 return p < _young_gen->reserved().end() && p != NULL;
884 }
885 #endif
886
887 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
888 NoHeaderExtendedOopClosure no_header_cl(cl);
889 oop_iterate(&no_header_cl);
890 }
891
892 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
893 _young_gen->oop_iterate(cl);
894 _old_gen->oop_iterate(cl);
895 }
896
897 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
898 _young_gen->object_iterate(cl);
899 _old_gen->object_iterate(cl);
900 }
901
902 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
903 _young_gen->safe_object_iterate(cl);
904 _old_gen->safe_object_iterate(cl);
905 }
906
907 Space* GenCollectedHeap::space_containing(const void* addr) const {
908 Space* res = _young_gen->space_containing(addr);
909 if (res != NULL) {
910 return res;
911 }
912 res = _old_gen->space_containing(addr);
913 assert(res != NULL, "Could not find containing space");
914 return res;
915 }
916
917 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
918 assert(is_in_reserved(addr), "block_start of address outside of heap");
919 if (_young_gen->is_in_reserved(addr)) {
920 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
921 return _young_gen->block_start(addr);
922 }
923
924 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
925 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
926 return _old_gen->block_start(addr);
927 }
928
929 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
930 assert(is_in_reserved(addr), "block_size of address outside of heap");
931 if (_young_gen->is_in_reserved(addr)) {
932 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
933 return _young_gen->block_size(addr);
934 }
935
936 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
937 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
938 return _old_gen->block_size(addr);
939 }
940
941 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
942 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
943 assert(block_start(addr) == addr, "addr must be a block start");
944 if (_young_gen->is_in_reserved(addr)) {
945 return _young_gen->block_is_obj(addr);
946 }
947
948 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
949 return _old_gen->block_is_obj(addr);
950 }
951
952 bool GenCollectedHeap::supports_tlab_allocation() const {
953 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
954 return _young_gen->supports_tlab_allocation();
955 }
956
957 size_t GenCollectedHeap::tlab_capacity(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_capacity();
961 }
962 return 0;
963 }
964
965 size_t GenCollectedHeap::tlab_used(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->tlab_used();
969 }
970 return 0;
971 }
972
973 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
974 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
975 if (_young_gen->supports_tlab_allocation()) {
976 return _young_gen->unsafe_max_tlab_alloc();
977 }
978 return 0;
979 }
980
981 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
982 bool gc_overhead_limit_was_exceeded;
983 return gen_policy()->mem_allocate_work(size /* size */,
984 true /* is_tlab */,
985 &gc_overhead_limit_was_exceeded);
986 }
987
988 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
989 // from the list headed by "*prev_ptr".
990 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
991 bool first = true;
992 size_t min_size = 0; // "first" makes this conceptually infinite.
993 ScratchBlock **smallest_ptr, *smallest;
994 ScratchBlock *cur = *prev_ptr;
995 while (cur) {
996 assert(*prev_ptr == cur, "just checking");
997 if (first || cur->num_words < min_size) {
998 smallest_ptr = prev_ptr;
999 smallest = cur;
1000 min_size = smallest->num_words;
1001 first = false;
1002 }
1003 prev_ptr = &cur->next;
1004 cur = cur->next;
1005 }
1006 smallest = *smallest_ptr;
1007 *smallest_ptr = smallest->next;
1008 return smallest;
1009 }
1010
1011 // Sort the scratch block list headed by res into decreasing size order,
1012 // and set "res" to the result.
1013 static void sort_scratch_list(ScratchBlock*& list) {
1014 ScratchBlock* sorted = NULL;
1015 ScratchBlock* unsorted = list;
1016 while (unsorted) {
1017 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1018 smallest->next = sorted;
1019 sorted = smallest;
1020 }
1021 list = sorted;
1022 }
1023
1024 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1025 size_t max_alloc_words) {
1026 ScratchBlock* res = NULL;
1027 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1028 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1029 sort_scratch_list(res);
1030 return res;
1031 }
1032
1033 void GenCollectedHeap::release_scratch() {
1034 _young_gen->reset_scratch();
1035 _old_gen->reset_scratch();
1036 }
1037
1038 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1039 void do_generation(Generation* gen) {
1040 gen->prepare_for_verify();
1041 }
1042 };
1043
1044 void GenCollectedHeap::prepare_for_verify() {
1045 ensure_parsability(false); // no need to retire TLABs
1046 GenPrepareForVerifyClosure blk;
1047 generation_iterate(&blk, false);
1048 }
1049
1050 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1051 bool old_to_young) {
1052 if (old_to_young) {
1053 cl->do_generation(_old_gen);
1054 cl->do_generation(_young_gen);
1055 } else {
1056 cl->do_generation(_young_gen);
1057 cl->do_generation(_old_gen);
1058 }
1059 }
1060
1061 bool GenCollectedHeap::is_maximal_no_gc() const {
1062 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1063 }
1064
1065 void GenCollectedHeap::save_marks() {
1066 _young_gen->save_marks();
1067 _old_gen->save_marks();
1068 }
1069
1070 GenCollectedHeap* GenCollectedHeap::heap() {
1071 CollectedHeap* heap = Universe::heap();
1072 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1073 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
1074 return (GenCollectedHeap*)heap;
1075 }
1076
1077 void GenCollectedHeap::prepare_for_compaction() {
1078 // Start by compacting into same gen.
1079 CompactPoint cp(_old_gen);
1080 _old_gen->prepare_for_compaction(&cp);
1081 _young_gen->prepare_for_compaction(&cp);
1082 }
1083
1084 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1085 log_debug(gc, verify)("%s", _old_gen->name());
1086 _old_gen->verify();
1087
1088 log_debug(gc, verify)("%s", _old_gen->name());
1089 _young_gen->verify();
1090
1091 log_debug(gc, verify)("RemSet");
1092 rem_set()->verify();
1093 }
1094
1095 void GenCollectedHeap::print_on(outputStream* st) const {
1096 _young_gen->print_on(st);
1097 _old_gen->print_on(st);
1098 MetaspaceAux::print_on(st);
1099 }
1100
1101 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1102 if (workers() != NULL) {
1103 workers()->threads_do(tc);
1104 }
1105 #if INCLUDE_ALL_GCS
1106 if (UseConcMarkSweepGC) {
1107 ConcurrentMarkSweepThread::threads_do(tc);
1108 }
1109 #endif // INCLUDE_ALL_GCS
1110 }
1111
1112 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1113 #if INCLUDE_ALL_GCS
1114 if (UseConcMarkSweepGC) {
1115 workers()->print_worker_threads_on(st);
1116 ConcurrentMarkSweepThread::print_all_on(st);
1117 }
1118 #endif // INCLUDE_ALL_GCS
1119 }
1120
1121 void GenCollectedHeap::print_on_error(outputStream* st) const {
1122 this->CollectedHeap::print_on_error(st);
1123
1124 #if INCLUDE_ALL_GCS
1125 if (UseConcMarkSweepGC) {
1126 st->cr();
1127 CMSCollector::print_on_error(st);
1128 }
1129 #endif // INCLUDE_ALL_GCS
1130 }
1131
1132 void GenCollectedHeap::print_tracing_info() const {
1133 if (TraceYoungGenTime) {
1134 _young_gen->print_summary_info();
1135 }
1136 if (TraceOldGenTime) {
1137 _old_gen->print_summary_info();
1138 }
1139 }
1140
1141 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1142 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1143 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1144 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1145 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1146 }
1147
1148 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1149 private:
1150 bool _full;
1151 public:
1152 void do_generation(Generation* gen) {
1153 gen->gc_prologue(_full);
1154 }
1155 GenGCPrologueClosure(bool full) : _full(full) {};
1156 };
1157
1158 void GenCollectedHeap::gc_prologue(bool full) {
1159 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1160
1161 always_do_update_barrier = false;
1162 // Fill TLAB's and such
1163 CollectedHeap::accumulate_statistics_all_tlabs();
1164 ensure_parsability(true); // retire TLABs
1165
1166 // Walk generations
1167 GenGCPrologueClosure blk(full);
1168 generation_iterate(&blk, false); // not old-to-young.
1169 };
1170
1171 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1172 private:
1173 bool _full;
1174 public:
1175 void do_generation(Generation* gen) {
1176 gen->gc_epilogue(_full);
1177 }
1178 GenGCEpilogueClosure(bool full) : _full(full) {};
1179 };
1180
1181 void GenCollectedHeap::gc_epilogue(bool full) {
1182 #if defined(COMPILER2) || INCLUDE_JVMCI
1183 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1184 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1185 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1186 #endif /* COMPILER2 || INCLUDE_JVMCI */
1187
1188 resize_all_tlabs();
1189
1190 GenGCEpilogueClosure blk(full);
1191 generation_iterate(&blk, false); // not old-to-young.
1192
1193 if (!CleanChunkPoolAsync) {
1194 Chunk::clean_chunk_pool();
1195 }
1196
1197 MetaspaceCounters::update_performance_counters();
1198 CompressedClassSpaceCounters::update_performance_counters();
1199
1200 always_do_update_barrier = UseConcMarkSweepGC;
1201 };
1202
1203 #ifndef PRODUCT
1204 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1205 private:
1206 public:
1207 void do_generation(Generation* gen) {
1208 gen->record_spaces_top();
1209 }
1210 };
1211
1212 void GenCollectedHeap::record_gen_tops_before_GC() {
1213 if (ZapUnusedHeapArea) {
1214 GenGCSaveTopsBeforeGCClosure blk;
1215 generation_iterate(&blk, false); // not old-to-young.
1216 }
1217 }
1218 #endif // not PRODUCT
1219
1220 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1221 public:
1222 void do_generation(Generation* gen) {
1223 gen->ensure_parsability();
1224 }
1225 };
1226
1227 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1228 CollectedHeap::ensure_parsability(retire_tlabs);
1229 GenEnsureParsabilityClosure ep_cl;
1230 generation_iterate(&ep_cl, false);
1231 }
1232
1233 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1234 oop obj,
1235 size_t obj_size) {
1236 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1237 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1238 HeapWord* result = NULL;
1239
1240 result = old_gen->expand_and_allocate(obj_size, false);
1241
1242 if (result != NULL) {
1243 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1244 }
1245 return oop(result);
1246 }
1247
1248 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1249 jlong _time; // in ms
1250 jlong _now; // in ms
1251
1252 public:
1253 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1254
1255 jlong time() { return _time; }
1256
1257 void do_generation(Generation* gen) {
1258 _time = MIN2(_time, gen->time_of_last_gc(_now));
1259 }
1260 };
1261
1262 jlong GenCollectedHeap::millis_since_last_gc() {
1263 // We need a monotonically non-decreasing time in ms but
1264 // os::javaTimeMillis() does not guarantee monotonicity.
1265 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1266 GenTimeOfLastGCClosure tolgc_cl(now);
1267 // iterate over generations getting the oldest
1268 // time that a generation was collected
1269 generation_iterate(&tolgc_cl, false);
1270
1271 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1272 // provided the underlying platform provides such a time source
1273 // (and it is bug free). So we still have to guard against getting
1274 // back a time later than 'now'.
1275 jlong retVal = now - tolgc_cl.time();
1276 if (retVal < 0) {
1277 NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, retVal);)
1278 return 0;
1279 }
1280 return retVal;
1281 }
1282
1283 void GenCollectedHeap::stop() {
1284 #if INCLUDE_ALL_GCS
1285 if (UseConcMarkSweepGC) {
1286 ConcurrentMarkSweepThread::cmst()->stop();
1287 }
1288 #endif
1289 }