1 /*
2 * Copyright (c) 2000, 2015, 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.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 collector_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::_last_ditch_collection;
299 }
300
301 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
302 if (!UseConcMarkSweepGC) {
303 return false;
304 }
305
306 switch (cause) {
307 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
308 case GCCause::_java_lang_system_gc:
309 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
310 default: return false;
311 }
312 }
313
314 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
315 bool is_tlab, bool run_verification, bool clear_soft_refs,
316 bool restore_marks_for_biased_locking) {
317 FormatBuffer<> title("Collect gen: %s", gen->short_name());
318 GCTraceTime(Debug, gc) t1(title);
319 TraceCollectorStats tcs(gen->counters());
320 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
321
322 gen->stat_record()->invocations++;
323 gen->stat_record()->accumulated_time.start();
324
325 // Must be done anew before each collection because
326 // a previous collection will do mangling and will
327 // change top of some spaces.
328 record_gen_tops_before_GC();
329
330 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
331
332 if (run_verification && VerifyBeforeGC) {
333 HandleMark hm; // Discard invalid handles created during verification
334 Universe::verify("Before GC");
335 }
336 COMPILER2_PRESENT(DerivedPointerTable::clear());
337
338 if (restore_marks_for_biased_locking) {
339 // We perform this mark word preservation work lazily
340 // because it's only at this point that we know whether we
341 // absolutely have to do it; we want to avoid doing it for
342 // scavenge-only collections where it's unnecessary
343 BiasedLocking::preserve_marks();
344 }
345
346 // Do collection work
347 {
348 // Note on ref discovery: For what appear to be historical reasons,
349 // GCH enables and disabled (by enqueing) refs discovery.
350 // In the future this should be moved into the generation's
351 // collect method so that ref discovery and enqueueing concerns
352 // are local to a generation. The collect method could return
353 // an appropriate indication in the case that notification on
354 // the ref lock was needed. This will make the treatment of
355 // weak refs more uniform (and indeed remove such concerns
356 // from GCH). XXX
357
358 HandleMark hm; // Discard invalid handles created during gc
359 save_marks(); // save marks for all gens
360 // We want to discover references, but not process them yet.
361 // This mode is disabled in process_discovered_references if the
362 // generation does some collection work, or in
363 // enqueue_discovered_references if the generation returns
364 // without doing any work.
365 ReferenceProcessor* rp = gen->ref_processor();
366 // If the discovery of ("weak") refs in this generation is
367 // atomic wrt other collectors in this configuration, we
368 // are guaranteed to have empty discovered ref lists.
369 if (rp->discovery_is_atomic()) {
370 rp->enable_discovery();
371 rp->setup_policy(clear_soft_refs);
372 } else {
373 // collect() below will enable discovery as appropriate
374 }
375 gen->collect(full, clear_soft_refs, size, is_tlab);
376 if (!rp->enqueuing_is_done()) {
377 rp->enqueue_discovered_references();
378 } else {
379 rp->set_enqueuing_is_done(false);
380 }
381 rp->verify_no_references_recorded();
382 }
383
384 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
385
386 gen->stat_record()->accumulated_time.stop();
387
388 update_gc_stats(gen, full);
389
390 if (run_verification && VerifyAfterGC) {
391 HandleMark hm; // Discard invalid handles created during verification
392 Universe::verify("After GC");
393 }
394 }
395
396 void GenCollectedHeap::do_collection(bool full,
397 bool clear_all_soft_refs,
398 size_t size,
399 bool is_tlab,
400 GenerationType max_generation) {
401 ResourceMark rm;
402 DEBUG_ONLY(Thread* my_thread = Thread::current();)
403
404 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
405 assert(my_thread->is_VM_thread() ||
406 my_thread->is_ConcurrentGC_thread(),
407 "incorrect thread type capability");
408 assert(Heap_lock->is_locked(),
409 "the requesting thread should have the Heap_lock");
410 guarantee(!is_gc_active(), "collection is not reentrant");
411
412 if (GC_locker::check_active_before_gc()) {
413 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
414 }
415
416 GCIdMarkAndRestore gc_id_mark;
417
418 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
419 collector_policy()->should_clear_all_soft_refs();
420
421 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
422
423 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
424
425 print_heap_before_gc();
426
427 {
428 FlagSetting fl(_is_gc_active, true);
429
430 bool complete = full && (max_generation == OldGen);
431 bool old_collects_young = complete && !ScavengeBeforeFullGC;
432 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
433
434 FormatBuffer<> gc_string("%s", "Pause ");
435 if (do_young_collection) {
436 gc_string.append("Young");
437 } else {
438 gc_string.append("Full");
439 }
440
441 GCTraceCPUTime tcpu;
442 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
443
444 gc_prologue(complete);
445 increment_total_collections(complete);
446
447 size_t young_prev_used = _young_gen->used();
448 size_t old_prev_used = _old_gen->used();
449
450 bool run_verification = total_collections() >= VerifyGCStartAt;
451
452 bool prepared_for_verification = false;
453 bool collected_old = false;
454
455 if (do_young_collection) {
456 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
457 prepare_for_verify();
458 prepared_for_verification = true;
459 }
460
461 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
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 pre_full_gc_dump(NULL); // do any pre full gc dumps
486
487 if (!prepared_for_verification && run_verification &&
488 VerifyGCLevel <= 1 && VerifyBeforeGC) {
489 prepare_for_verify();
490 }
491
492 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
493
494 if (do_young_collection) {
495 // We did a young GC. Need a new GC id for the old GC.
496 GCIdMarkAndRestore gc_id_mark;
497 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
498 } else {
499 // No young GC done. Use the same GC id as was set up earlier in this method.
500 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
501 }
502
503 must_restore_marks_for_biased_locking = true;
504 collected_old = true;
505 }
506
507 // Update "complete" boolean wrt what actually transpired --
508 // for instance, a promotion failure could have led to
509 // a whole heap collection.
510 complete = complete || collected_old;
511
512 if (complete) { // We did a full collection
513 // FIXME: See comment at pre_full_gc_dump call
514 post_full_gc_dump(NULL); // do any post full gc dumps
515 }
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 collector_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 CodeBlobClosure* 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 CodeBlobClosure* 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
697 class AlwaysTrueClosure: public BoolObjectClosure {
698 public:
699 bool do_object_b(oop p) { return true; }
700 };
701 static AlwaysTrueClosure always_true;
702
703 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
704 JNIHandles::weak_oops_do(&always_true, root_closure);
705 _young_gen->ref_processor()->weak_oops_do(root_closure);
706 _old_gen->ref_processor()->weak_oops_do(root_closure);
707 }
708
709 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
710 void GenCollectedHeap:: \
711 oop_since_save_marks_iterate(GenerationType gen, \
712 OopClosureType* cur, \
713 OopClosureType* older) { \
714 if (gen == YoungGen) { \
715 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
716 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
717 } else { \
718 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
719 } \
720 }
721
722 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
723
724 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
725
726 bool GenCollectedHeap::no_allocs_since_save_marks() {
727 return _young_gen->no_allocs_since_save_marks() &&
728 _old_gen->no_allocs_since_save_marks();
729 }
730
731 bool GenCollectedHeap::supports_inline_contig_alloc() const {
732 return _young_gen->supports_inline_contig_alloc();
733 }
734
735 HeapWord** GenCollectedHeap::top_addr() const {
736 return _young_gen->top_addr();
737 }
738
739 HeapWord** GenCollectedHeap::end_addr() const {
740 return _young_gen->end_addr();
741 }
742
743 // public collection interfaces
744
745 void GenCollectedHeap::collect(GCCause::Cause cause) {
746 if (should_do_concurrent_full_gc(cause)) {
747 #if INCLUDE_ALL_GCS
748 // Mostly concurrent full collection.
749 collect_mostly_concurrent(cause);
750 #else // INCLUDE_ALL_GCS
751 ShouldNotReachHere();
752 #endif // INCLUDE_ALL_GCS
753 } else if (cause == GCCause::_wb_young_gc) {
754 // Young collection for the WhiteBox API.
755 collect(cause, YoungGen);
756 } else {
757 #ifdef ASSERT
758 if (cause == GCCause::_scavenge_alot) {
759 // Young collection only.
760 collect(cause, YoungGen);
761 } else {
762 // Stop-the-world full collection.
763 collect(cause, OldGen);
764 }
765 #else
766 // Stop-the-world full collection.
767 collect(cause, OldGen);
768 #endif
769 }
770 }
771
772 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
773 // The caller doesn't have the Heap_lock
774 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
775 MutexLocker ml(Heap_lock);
776 collect_locked(cause, max_generation);
777 }
778
779 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
780 // The caller has the Heap_lock
781 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
782 collect_locked(cause, OldGen);
783 }
784
785 // this is the private collection interface
786 // The Heap_lock is expected to be held on entry.
787
788 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
789 // Read the GC count while holding the Heap_lock
790 unsigned int gc_count_before = total_collections();
791 unsigned int full_gc_count_before = total_full_collections();
792 {
793 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
794 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
795 cause, max_generation);
796 VMThread::execute(&op);
797 }
798 }
799
800 #if INCLUDE_ALL_GCS
801 bool GenCollectedHeap::create_cms_collector() {
802
803 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
804 "Unexpected generation kinds");
805 // Skip two header words in the block content verification
806 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
807 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type");
808 CMSCollector* collector =
809 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen,
810 _rem_set,
811 _gen_policy->as_concurrent_mark_sweep_policy());
812
813 if (collector == NULL || !collector->completed_initialization()) {
814 if (collector) {
815 delete collector; // Be nice in embedded situation
816 }
817 vm_shutdown_during_initialization("Could not create CMS collector");
818 return false;
819 }
820 return true; // success
821 }
822
823 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
824 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
825
826 MutexLocker ml(Heap_lock);
827 // Read the GC counts while holding the Heap_lock
828 unsigned int full_gc_count_before = total_full_collections();
829 unsigned int gc_count_before = total_collections();
830 {
831 MutexUnlocker mu(Heap_lock);
832 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
833 VMThread::execute(&op);
834 }
835 }
836 #endif // INCLUDE_ALL_GCS
837
838 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
839 do_full_collection(clear_all_soft_refs, OldGen);
840 }
841
842 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
843 GenerationType last_generation) {
844 GenerationType local_last_generation;
845 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
846 gc_cause() == GCCause::_gc_locker) {
847 local_last_generation = YoungGen;
848 } else {
849 local_last_generation = last_generation;
850 }
851
852 do_collection(true, // full
853 clear_all_soft_refs, // clear_all_soft_refs
854 0, // size
855 false, // is_tlab
856 local_last_generation); // last_generation
857 // Hack XXX FIX ME !!!
858 // A scavenge may not have been attempted, or may have
859 // been attempted and failed, because the old gen was too full
860 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
861 incremental_collection_will_fail(false /* don't consult_young */)) {
862 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
863 // This time allow the old gen to be collected as well
864 do_collection(true, // full
865 clear_all_soft_refs, // clear_all_soft_refs
866 0, // size
867 false, // is_tlab
868 OldGen); // last_generation
869 }
870 }
871
872 bool GenCollectedHeap::is_in_young(oop p) {
873 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
874 assert(result == _young_gen->is_in_reserved(p),
875 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
876 return result;
877 }
878
879 // Returns "TRUE" iff "p" points into the committed areas of the heap.
880 bool GenCollectedHeap::is_in(const void* p) const {
881 return _young_gen->is_in(p) || _old_gen->is_in(p);
882 }
883
884 #ifdef ASSERT
885 // Don't implement this by using is_in_young(). This method is used
886 // in some cases to check that is_in_young() is correct.
887 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
888 assert(is_in_reserved(p) || p == NULL,
889 "Does not work if address is non-null and outside of the heap");
890 return p < _young_gen->reserved().end() && p != NULL;
891 }
892 #endif
893
894 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
895 NoHeaderExtendedOopClosure no_header_cl(cl);
896 oop_iterate(&no_header_cl);
897 }
898
899 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
900 _young_gen->oop_iterate(cl);
901 _old_gen->oop_iterate(cl);
902 }
903
904 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
905 _young_gen->object_iterate(cl);
906 _old_gen->object_iterate(cl);
907 }
908
909 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
910 _young_gen->safe_object_iterate(cl);
911 _old_gen->safe_object_iterate(cl);
912 }
913
914 Space* GenCollectedHeap::space_containing(const void* addr) const {
915 Space* res = _young_gen->space_containing(addr);
916 if (res != NULL) {
917 return res;
918 }
919 res = _old_gen->space_containing(addr);
920 assert(res != NULL, "Could not find containing space");
921 return res;
922 }
923
924 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
925 assert(is_in_reserved(addr), "block_start of address outside of heap");
926 if (_young_gen->is_in_reserved(addr)) {
927 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
928 return _young_gen->block_start(addr);
929 }
930
931 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
932 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
933 return _old_gen->block_start(addr);
934 }
935
936 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
937 assert(is_in_reserved(addr), "block_size of address outside of heap");
938 if (_young_gen->is_in_reserved(addr)) {
939 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
940 return _young_gen->block_size(addr);
941 }
942
943 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
944 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
945 return _old_gen->block_size(addr);
946 }
947
948 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
949 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
950 assert(block_start(addr) == addr, "addr must be a block start");
951 if (_young_gen->is_in_reserved(addr)) {
952 return _young_gen->block_is_obj(addr);
953 }
954
955 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
956 return _old_gen->block_is_obj(addr);
957 }
958
959 bool GenCollectedHeap::supports_tlab_allocation() const {
960 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
961 return _young_gen->supports_tlab_allocation();
962 }
963
964 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
965 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
966 if (_young_gen->supports_tlab_allocation()) {
967 return _young_gen->tlab_capacity();
968 }
969 return 0;
970 }
971
972 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
973 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
974 if (_young_gen->supports_tlab_allocation()) {
975 return _young_gen->tlab_used();
976 }
977 return 0;
978 }
979
980 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
981 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
982 if (_young_gen->supports_tlab_allocation()) {
983 return _young_gen->unsafe_max_tlab_alloc();
984 }
985 return 0;
986 }
987
988 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
989 bool gc_overhead_limit_was_exceeded;
990 return collector_policy()->mem_allocate_work(size /* size */,
991 true /* is_tlab */,
992 &gc_overhead_limit_was_exceeded);
993 }
994
995 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
996 // from the list headed by "*prev_ptr".
997 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
998 bool first = true;
999 size_t min_size = 0; // "first" makes this conceptually infinite.
1000 ScratchBlock **smallest_ptr, *smallest;
1001 ScratchBlock *cur = *prev_ptr;
1002 while (cur) {
1003 assert(*prev_ptr == cur, "just checking");
1004 if (first || cur->num_words < min_size) {
1005 smallest_ptr = prev_ptr;
1006 smallest = cur;
1007 min_size = smallest->num_words;
1008 first = false;
1009 }
1010 prev_ptr = &cur->next;
1011 cur = cur->next;
1012 }
1013 smallest = *smallest_ptr;
1014 *smallest_ptr = smallest->next;
1015 return smallest;
1016 }
1017
1018 // Sort the scratch block list headed by res into decreasing size order,
1019 // and set "res" to the result.
1020 static void sort_scratch_list(ScratchBlock*& list) {
1021 ScratchBlock* sorted = NULL;
1022 ScratchBlock* unsorted = list;
1023 while (unsorted) {
1024 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1025 smallest->next = sorted;
1026 sorted = smallest;
1027 }
1028 list = sorted;
1029 }
1030
1031 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1032 size_t max_alloc_words) {
1033 ScratchBlock* res = NULL;
1034 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1035 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1036 sort_scratch_list(res);
1037 return res;
1038 }
1039
1040 void GenCollectedHeap::release_scratch() {
1041 _young_gen->reset_scratch();
1042 _old_gen->reset_scratch();
1043 }
1044
1045 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1046 void do_generation(Generation* gen) {
1047 gen->prepare_for_verify();
1048 }
1049 };
1050
1051 void GenCollectedHeap::prepare_for_verify() {
1052 ensure_parsability(false); // no need to retire TLABs
1053 GenPrepareForVerifyClosure blk;
1054 generation_iterate(&blk, false);
1055 }
1056
1057 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1058 bool old_to_young) {
1059 if (old_to_young) {
1060 cl->do_generation(_old_gen);
1061 cl->do_generation(_young_gen);
1062 } else {
1063 cl->do_generation(_young_gen);
1064 cl->do_generation(_old_gen);
1065 }
1066 }
1067
1068 bool GenCollectedHeap::is_maximal_no_gc() const {
1069 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1070 }
1071
1072 void GenCollectedHeap::save_marks() {
1073 _young_gen->save_marks();
1074 _old_gen->save_marks();
1075 }
1076
1077 GenCollectedHeap* GenCollectedHeap::heap() {
1078 CollectedHeap* heap = Universe::heap();
1079 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1080 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
1081 return (GenCollectedHeap*)heap;
1082 }
1083
1084 void GenCollectedHeap::prepare_for_compaction() {
1085 // Start by compacting into same gen.
1086 CompactPoint cp(_old_gen);
1087 _old_gen->prepare_for_compaction(&cp);
1088 _young_gen->prepare_for_compaction(&cp);
1089 }
1090
1091 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1092 log_debug(gc, verify)("%s", _old_gen->name());
1093 _old_gen->verify();
1094
1095 log_debug(gc, verify)("%s", _old_gen->name());
1096 _young_gen->verify();
1097
1098 log_debug(gc, verify)("RemSet");
1099 rem_set()->verify();
1100 }
1101
1102 void GenCollectedHeap::print_on(outputStream* st) const {
1103 _young_gen->print_on(st);
1104 _old_gen->print_on(st);
1105 MetaspaceAux::print_on(st);
1106 }
1107
1108 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1109 if (workers() != NULL) {
1110 workers()->threads_do(tc);
1111 }
1112 #if INCLUDE_ALL_GCS
1113 if (UseConcMarkSweepGC) {
1114 ConcurrentMarkSweepThread::threads_do(tc);
1115 }
1116 #endif // INCLUDE_ALL_GCS
1117 }
1118
1119 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1120 #if INCLUDE_ALL_GCS
1121 if (UseConcMarkSweepGC) {
1122 workers()->print_worker_threads_on(st);
1123 ConcurrentMarkSweepThread::print_all_on(st);
1124 }
1125 #endif // INCLUDE_ALL_GCS
1126 }
1127
1128 void GenCollectedHeap::print_on_error(outputStream* st) const {
1129 this->CollectedHeap::print_on_error(st);
1130
1131 #if INCLUDE_ALL_GCS
1132 if (UseConcMarkSweepGC) {
1133 st->cr();
1134 CMSCollector::print_on_error(st);
1135 }
1136 #endif // INCLUDE_ALL_GCS
1137 }
1138
1139 void GenCollectedHeap::print_tracing_info() const {
1140 if (TraceYoungGenTime) {
1141 _young_gen->print_summary_info();
1142 }
1143 if (TraceOldGenTime) {
1144 _old_gen->print_summary_info();
1145 }
1146 }
1147
1148 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1149 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1150 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1151 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1152 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1153 }
1154
1155 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1156 private:
1157 bool _full;
1158 public:
1159 void do_generation(Generation* gen) {
1160 gen->gc_prologue(_full);
1161 }
1162 GenGCPrologueClosure(bool full) : _full(full) {};
1163 };
1164
1165 void GenCollectedHeap::gc_prologue(bool full) {
1166 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1167
1168 always_do_update_barrier = false;
1169 // Fill TLAB's and such
1170 CollectedHeap::accumulate_statistics_all_tlabs();
1171 ensure_parsability(true); // retire TLABs
1172
1173 // Walk generations
1174 GenGCPrologueClosure blk(full);
1175 generation_iterate(&blk, false); // not old-to-young.
1176 };
1177
1178 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1179 private:
1180 bool _full;
1181 public:
1182 void do_generation(Generation* gen) {
1183 gen->gc_epilogue(_full);
1184 }
1185 GenGCEpilogueClosure(bool full) : _full(full) {};
1186 };
1187
1188 void GenCollectedHeap::gc_epilogue(bool full) {
1189 #if defined(COMPILER2) || INCLUDE_JVMCI
1190 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1191 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1192 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1193 #endif /* COMPILER2 || INCLUDE_JVMCI */
1194
1195 resize_all_tlabs();
1196
1197 GenGCEpilogueClosure blk(full);
1198 generation_iterate(&blk, false); // not old-to-young.
1199
1200 if (!CleanChunkPoolAsync) {
1201 Chunk::clean_chunk_pool();
1202 }
1203
1204 MetaspaceCounters::update_performance_counters();
1205 CompressedClassSpaceCounters::update_performance_counters();
1206
1207 always_do_update_barrier = UseConcMarkSweepGC;
1208 };
1209
1210 #ifndef PRODUCT
1211 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1212 private:
1213 public:
1214 void do_generation(Generation* gen) {
1215 gen->record_spaces_top();
1216 }
1217 };
1218
1219 void GenCollectedHeap::record_gen_tops_before_GC() {
1220 if (ZapUnusedHeapArea) {
1221 GenGCSaveTopsBeforeGCClosure blk;
1222 generation_iterate(&blk, false); // not old-to-young.
1223 }
1224 }
1225 #endif // not PRODUCT
1226
1227 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1228 public:
1229 void do_generation(Generation* gen) {
1230 gen->ensure_parsability();
1231 }
1232 };
1233
1234 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1235 CollectedHeap::ensure_parsability(retire_tlabs);
1236 GenEnsureParsabilityClosure ep_cl;
1237 generation_iterate(&ep_cl, false);
1238 }
1239
1240 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1241 oop obj,
1242 size_t obj_size) {
1243 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1244 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1245 HeapWord* result = NULL;
1246
1247 result = old_gen->expand_and_allocate(obj_size, false);
1248
1249 if (result != NULL) {
1250 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1251 }
1252 return oop(result);
1253 }
1254
1255 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1256 jlong _time; // in ms
1257 jlong _now; // in ms
1258
1259 public:
1260 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1261
1262 jlong time() { return _time; }
1263
1264 void do_generation(Generation* gen) {
1265 _time = MIN2(_time, gen->time_of_last_gc(_now));
1266 }
1267 };
1268
1269 jlong GenCollectedHeap::millis_since_last_gc() {
1270 // We need a monotonically non-decreasing time in ms but
1271 // os::javaTimeMillis() does not guarantee monotonicity.
1272 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1273 GenTimeOfLastGCClosure tolgc_cl(now);
1274 // iterate over generations getting the oldest
1275 // time that a generation was collected
1276 generation_iterate(&tolgc_cl, false);
1277
1278 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1279 // provided the underlying platform provides such a time source
1280 // (and it is bug free). So we still have to guard against getting
1281 // back a time later than 'now'.
1282 jlong retVal = now - tolgc_cl.time();
1283 if (retVal < 0) {
1284 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1285 return 0;
1286 }
1287 return retVal;
1288 }