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/gcLocker.inline.hpp"
34 #include "gc/shared/gcTrace.hpp"
35 #include "gc/shared/gcTraceTime.hpp"
36 #include "gc/shared/genCollectedHeap.hpp"
37 #include "gc/shared/genOopClosures.inline.hpp"
38 #include "gc/shared/generationSpec.hpp"
39 #include "gc/shared/space.hpp"
40 #include "gc/shared/strongRootsScope.hpp"
41 #include "gc/shared/vmGCOperations.hpp"
42 #include "gc/shared/workgroup.hpp"
43 #include "memory/filemap.hpp"
44 #include "memory/resourceArea.hpp"
45 #include "oops/oop.inline.hpp"
46 #include "runtime/biasedLocking.hpp"
47 #include "runtime/fprofiler.hpp"
48 #include "runtime/handles.hpp"
49 #include "runtime/handles.inline.hpp"
50 #include "runtime/java.hpp"
51 #include "runtime/vmThread.hpp"
52 #include "services/management.hpp"
53 #include "services/memoryService.hpp"
54 #include "utilities/macros.hpp"
55 #include "utilities/stack.inline.hpp"
56 #include "utilities/vmError.hpp"
57 #if INCLUDE_ALL_GCS
58 #include "gc/cms/concurrentMarkSweepThread.hpp"
59 #include "gc/cms/vmCMSOperations.hpp"
60 #endif // INCLUDE_ALL_GCS
61
62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
63
64 // The set of potentially parallel tasks in root scanning.
65 enum GCH_strong_roots_tasks {
66 GCH_PS_Universe_oops_do,
67 GCH_PS_JNIHandles_oops_do,
68 GCH_PS_ObjectSynchronizer_oops_do,
69 GCH_PS_FlatProfiler_oops_do,
70 GCH_PS_Management_oops_do,
71 GCH_PS_SystemDictionary_oops_do,
72 GCH_PS_ClassLoaderDataGraph_oops_do,
73 GCH_PS_jvmti_oops_do,
74 GCH_PS_CodeCache_oops_do,
75 GCH_PS_younger_gens,
76 // Leave this one last.
77 GCH_PS_NumElements
78 };
79
80 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
81 CollectedHeap(),
82 _rem_set(NULL),
83 _gen_policy(policy),
84 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
85 _full_collections_completed(0)
86 {
87 assert(policy != NULL, "Sanity check");
88 if (UseConcMarkSweepGC) {
89 _workers = new WorkGang("GC Thread", ParallelGCThreads,
90 /* are_GC_task_threads */true,
91 /* are_ConcurrentGC_threads */false);
92 _workers->initialize_workers();
93 } else {
94 // Serial GC does not use workers.
95 _workers = NULL;
96 }
97 }
98
99 jint GenCollectedHeap::initialize() {
100 CollectedHeap::pre_initialize();
101
102 // While there are no constraints in the GC code that HeapWordSize
103 // be any particular value, there are multiple other areas in the
104 // system which believe this to be true (e.g. oop->object_size in some
105 // cases incorrectly returns the size in wordSize units rather than
106 // HeapWordSize).
107 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
108
109 // Allocate space for the heap.
110
111 char* heap_address;
112 ReservedSpace heap_rs;
113
114 size_t heap_alignment = collector_policy()->heap_alignment();
115
116 heap_address = allocate(heap_alignment, &heap_rs);
117
118 if (!heap_rs.is_reserved()) {
119 vm_shutdown_during_initialization(
120 "Could not reserve enough space for object heap");
121 return JNI_ENOMEM;
122 }
123
124 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
125
126 _rem_set = collector_policy()->create_rem_set(reserved_region());
127 set_barrier_set(rem_set()->bs());
128
129 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
130 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set());
131 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
132
133 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
134 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set());
135 clear_incremental_collection_failed();
136
137 #if INCLUDE_ALL_GCS
138 // If we are running CMS, create the collector responsible
139 // for collecting the CMS generations.
140 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
141 bool success = create_cms_collector();
142 if (!success) return JNI_ENOMEM;
143 }
144 #endif // INCLUDE_ALL_GCS
145
146 return JNI_OK;
147 }
148
149 char* GenCollectedHeap::allocate(size_t alignment,
150 ReservedSpace* heap_rs){
151 // Now figure out the total size.
152 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
153 assert(alignment % pageSize == 0, "Must be");
154
155 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
156 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
157
158 // Check for overflow.
159 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
160 if (total_reserved < young_spec->max_size()) {
161 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
162 "the maximum representable size");
163 }
164 assert(total_reserved % alignment == 0,
165 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
166 SIZE_FORMAT, total_reserved, alignment));
167
168 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
169 return heap_rs->base();
170 }
171
172 void GenCollectedHeap::post_initialize() {
173 CollectedHeap::post_initialize();
174 ref_processing_init();
175 assert((_young_gen->kind() == Generation::DefNew) ||
176 (_young_gen->kind() == Generation::ParNew),
177 "Wrong youngest generation type");
178 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
179
180 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
181 _old_gen->kind() == Generation::MarkSweepCompact,
182 "Wrong generation kind");
183
184 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
185 _old_gen->capacity(),
186 def_new_gen->from()->capacity());
187 _gen_policy->initialize_gc_policy_counters();
188 }
189
190 void GenCollectedHeap::ref_processing_init() {
191 _young_gen->ref_processor_init();
192 _old_gen->ref_processor_init();
193 }
194
195 size_t GenCollectedHeap::capacity() const {
196 return _young_gen->capacity() + _old_gen->capacity();
197 }
198
199 size_t GenCollectedHeap::used() const {
200 return _young_gen->used() + _old_gen->used();
201 }
202
203 void GenCollectedHeap::save_used_regions() {
204 _old_gen->save_used_region();
205 _young_gen->save_used_region();
206 }
207
208 size_t GenCollectedHeap::max_capacity() const {
209 return _young_gen->max_capacity() + _old_gen->max_capacity();
210 }
211
212 // Update the _full_collections_completed counter
213 // at the end of a stop-world full GC.
214 unsigned int GenCollectedHeap::update_full_collections_completed() {
215 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
216 assert(_full_collections_completed <= _total_full_collections,
217 "Can't complete more collections than were started");
218 _full_collections_completed = _total_full_collections;
219 ml.notify_all();
220 return _full_collections_completed;
221 }
222
223 // Update the _full_collections_completed counter, as appropriate,
224 // at the end of a concurrent GC cycle. Note the conditional update
225 // below to allow this method to be called by a concurrent collector
226 // without synchronizing in any manner with the VM thread (which
227 // may already have initiated a STW full collection "concurrently").
228 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
229 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
230 assert((_full_collections_completed <= _total_full_collections) &&
231 (count <= _total_full_collections),
232 "Can't complete more collections than were started");
233 if (count > _full_collections_completed) {
234 _full_collections_completed = count;
235 ml.notify_all();
236 }
237 return _full_collections_completed;
238 }
239
240
241 #ifndef PRODUCT
242 // Override of memory state checking method in CollectedHeap:
243 // Some collectors (CMS for example) can't have badHeapWordVal written
244 // in the first two words of an object. (For instance , in the case of
245 // CMS these words hold state used to synchronize between certain
246 // (concurrent) GC steps and direct allocating mutators.)
247 // The skip_header_HeapWords() method below, allows us to skip
248 // over the requisite number of HeapWord's. Note that (for
249 // generational collectors) this means that those many words are
250 // skipped in each object, irrespective of the generation in which
251 // that object lives. The resultant loss of precision seems to be
252 // harmless and the pain of avoiding that imprecision appears somewhat
253 // higher than we are prepared to pay for such rudimentary debugging
254 // support.
255 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
256 size_t size) {
257 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
258 // We are asked to check a size in HeapWords,
259 // but the memory is mangled in juint words.
260 juint* start = (juint*) (addr + skip_header_HeapWords());
261 juint* end = (juint*) (addr + size);
262 for (juint* slot = start; slot < end; slot += 1) {
263 assert(*slot == badHeapWordVal,
264 "Found non badHeapWordValue in pre-allocation check");
265 }
266 }
267 }
268 #endif
269
270 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
271 bool is_tlab,
272 bool first_only) {
273 HeapWord* res = NULL;
274
275 if (_young_gen->should_allocate(size, is_tlab)) {
276 res = _young_gen->allocate(size, is_tlab);
277 if (res != NULL || first_only) {
278 return res;
279 }
280 }
281
282 if (_old_gen->should_allocate(size, is_tlab)) {
283 res = _old_gen->allocate(size, is_tlab);
284 }
285
286 return res;
287 }
288
289 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
290 bool* gc_overhead_limit_was_exceeded) {
291 return collector_policy()->mem_allocate_work(size,
292 false /* is_tlab */,
293 gc_overhead_limit_was_exceeded);
294 }
295
296 bool GenCollectedHeap::must_clear_all_soft_refs() {
297 return _gc_cause == GCCause::_last_ditch_collection;
298 }
299
300 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
301 if (!UseConcMarkSweepGC) {
302 return false;
303 }
304
305 switch (cause) {
306 case GCCause::_gc_locker: return GCLockerInvokesConcurrent;
307 case GCCause::_java_lang_system_gc:
308 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent;
309 default: return false;
310 }
311 }
312
313 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
314 bool is_tlab, bool run_verification, bool clear_soft_refs,
315 bool restore_marks_for_biased_locking) {
316 // Timer for individual generations. Last argument is false: no CR
317 // FIXME: We should try to start the timing earlier to cover more of the GC pause
318 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
319 // so we can assume here that the next GC id is what we want.
320 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
321 TraceCollectorStats tcs(gen->counters());
322 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
323
324 size_t prev_used = gen->used();
325 gen->stat_record()->invocations++;
326 gen->stat_record()->accumulated_time.start();
327
328 // Must be done anew before each collection because
329 // a previous collection will do mangling and will
330 // change top of some spaces.
331 record_gen_tops_before_GC();
332
333 if (PrintGC && Verbose) {
334 // I didn't want to change the logging when removing the level concept,
335 // but I guess this logging could say young/old or something instead of 0/1.
336 uint level;
337 if (heap()->is_young_gen(gen)) {
338 level = 0;
339 } else {
340 level = 1;
341 }
342 gclog_or_tty->print("level=%u invoke=%d size=" SIZE_FORMAT,
343 level,
344 gen->stat_record()->invocations,
345 size * HeapWordSize);
346 }
347
348 if (run_verification && VerifyBeforeGC) {
349 HandleMark hm; // Discard invalid handles created during verification
350 Universe::verify(" VerifyBeforeGC:");
351 }
352 COMPILER2_PRESENT(DerivedPointerTable::clear());
353
354 if (restore_marks_for_biased_locking) {
355 // We perform this mark word preservation work lazily
356 // because it's only at this point that we know whether we
357 // absolutely have to do it; we want to avoid doing it for
358 // scavenge-only collections where it's unnecessary
359 BiasedLocking::preserve_marks();
360 }
361
362 // Do collection work
363 {
364 // Note on ref discovery: For what appear to be historical reasons,
365 // GCH enables and disabled (by enqueing) refs discovery.
366 // In the future this should be moved into the generation's
367 // collect method so that ref discovery and enqueueing concerns
368 // are local to a generation. The collect method could return
369 // an appropriate indication in the case that notification on
370 // the ref lock was needed. This will make the treatment of
371 // weak refs more uniform (and indeed remove such concerns
372 // from GCH). XXX
373
374 HandleMark hm; // Discard invalid handles created during gc
375 save_marks(); // save marks for all gens
376 // We want to discover references, but not process them yet.
377 // This mode is disabled in process_discovered_references if the
378 // generation does some collection work, or in
379 // enqueue_discovered_references if the generation returns
380 // without doing any work.
381 ReferenceProcessor* rp = gen->ref_processor();
382 // If the discovery of ("weak") refs in this generation is
383 // atomic wrt other collectors in this configuration, we
384 // are guaranteed to have empty discovered ref lists.
385 if (rp->discovery_is_atomic()) {
386 rp->enable_discovery();
387 rp->setup_policy(clear_soft_refs);
388 } else {
389 // collect() below will enable discovery as appropriate
390 }
391 gen->collect(full, clear_soft_refs, size, is_tlab);
392 if (!rp->enqueuing_is_done()) {
393 rp->enqueue_discovered_references();
394 } else {
395 rp->set_enqueuing_is_done(false);
396 }
397 rp->verify_no_references_recorded();
398 }
399
400 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
401
402 gen->stat_record()->accumulated_time.stop();
403
404 update_gc_stats(gen, full);
405
406 if (run_verification && VerifyAfterGC) {
407 HandleMark hm; // Discard invalid handles created during verification
408 Universe::verify(" VerifyAfterGC:");
409 }
410
411 if (PrintGCDetails) {
412 gclog_or_tty->print(":");
413 gen->print_heap_change(prev_used);
414 }
415 }
416
417 void GenCollectedHeap::do_collection(bool full,
418 bool clear_all_soft_refs,
419 size_t size,
420 bool is_tlab,
421 GenerationType max_generation) {
422 ResourceMark rm;
423 DEBUG_ONLY(Thread* my_thread = Thread::current();)
424
425 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
426 assert(my_thread->is_VM_thread() ||
427 my_thread->is_ConcurrentGC_thread(),
428 "incorrect thread type capability");
429 assert(Heap_lock->is_locked(),
430 "the requesting thread should have the Heap_lock");
431 guarantee(!is_gc_active(), "collection is not reentrant");
432
433 if (GC_locker::check_active_before_gc()) {
434 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
435 }
436
437 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
438 collector_policy()->should_clear_all_soft_refs();
439
440 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
441
442 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
443
444 print_heap_before_gc();
445
446 {
447 FlagSetting fl(_is_gc_active, true);
448
449 bool complete = full && (max_generation == OldGen);
450 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
451 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
452 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
453 // so we can assume here that the next GC id is what we want.
454 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
455
456 gc_prologue(complete);
457 increment_total_collections(complete);
458
459 size_t gch_prev_used = used();
460 bool run_verification = total_collections() >= VerifyGCStartAt;
461
462 bool prepared_for_verification = false;
463 bool collected_old = false;
464 bool old_collects_young = complete &&
465 _old_gen->full_collects_young_generation();
466 if (!old_collects_young &&
467 _young_gen->should_collect(full, size, is_tlab)) {
468 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
469 prepare_for_verify();
470 prepared_for_verification = true;
471 }
472
473 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
474 collect_generation(_young_gen,
475 full,
476 size,
477 is_tlab,
478 run_verification && VerifyGCLevel <= 0,
479 do_clear_all_soft_refs,
480 false);
481
482 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
483 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
484 // Allocation request was met by young GC.
485 size = 0;
486 }
487 }
488
489 bool must_restore_marks_for_biased_locking = false;
490
491 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
492 if (!complete) {
493 // The full_collections increment was missed above.
494 increment_total_full_collections();
495 }
496
497 pre_full_gc_dump(NULL); // do any pre full gc dumps
498
499 if (!prepared_for_verification && run_verification &&
500 VerifyGCLevel <= 1 && VerifyBeforeGC) {
501 prepare_for_verify();
502 }
503
504 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
505 collect_generation(_old_gen,
506 full,
507 size,
508 is_tlab,
509 run_verification && VerifyGCLevel <= 1,
510 do_clear_all_soft_refs,
511 true);
512
513 must_restore_marks_for_biased_locking = true;
514 collected_old = true;
515 }
516
517 // Update "complete" boolean wrt what actually transpired --
518 // for instance, a promotion failure could have led to
519 // a whole heap collection.
520 complete = complete || collected_old;
521
522 if (complete) { // We did a full collection
523 // FIXME: See comment at pre_full_gc_dump call
524 post_full_gc_dump(NULL); // do any post full gc dumps
525 }
526
527 if (PrintGCDetails) {
528 print_heap_change(gch_prev_used);
529
530 // Print metaspace info for full GC with PrintGCDetails flag.
531 if (complete) {
532 MetaspaceAux::print_metaspace_change(metadata_prev_used);
533 }
534 }
535
536 // Adjust generation sizes.
537 if (collected_old) {
538 _old_gen->compute_new_size();
539 }
540 _young_gen->compute_new_size();
541
542 if (complete) {
543 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
544 ClassLoaderDataGraph::purge();
545 MetaspaceAux::verify_metrics();
546 // Resize the metaspace capacity after full collections
547 MetaspaceGC::compute_new_size();
548 update_full_collections_completed();
549 }
550
551 // Track memory usage and detect low memory after GC finishes
552 MemoryService::track_memory_usage();
553
554 gc_epilogue(complete);
555
556 if (must_restore_marks_for_biased_locking) {
557 BiasedLocking::restore_marks();
558 }
559 }
560
561 print_heap_after_gc();
562
563 #ifdef TRACESPINNING
564 ParallelTaskTerminator::print_termination_counts();
565 #endif
566 }
567
568 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
569 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
570 }
571
572 #ifdef ASSERT
573 class AssertNonScavengableClosure: public OopClosure {
574 public:
575 virtual void do_oop(oop* p) {
576 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
577 "Referent should not be scavengable."); }
578 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
579 };
580 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
581 #endif
582
583 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
584 ScanningOption so,
585 OopClosure* strong_roots,
586 OopClosure* weak_roots,
587 CLDClosure* strong_cld_closure,
588 CLDClosure* weak_cld_closure,
589 CodeBlobClosure* code_roots) {
590 // General roots.
591 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
592 assert(code_roots != NULL, "code root closure should always be set");
593 // _n_termination for _process_strong_tasks should be set up stream
594 // in a method not running in a GC worker. Otherwise the GC worker
595 // could be trying to change the termination condition while the task
596 // is executing in another GC worker.
597
598 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
599 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
600 }
601
602 // Some CLDs contained in the thread frames should be considered strong.
603 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
604 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
605 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
606 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
607
608 bool is_par = scope->n_threads() > 1;
609 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
610
611 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
612 Universe::oops_do(strong_roots);
613 }
614 // Global (strong) JNI handles
615 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
616 JNIHandles::oops_do(strong_roots);
617 }
618
619 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
620 ObjectSynchronizer::oops_do(strong_roots);
621 }
622 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
623 FlatProfiler::oops_do(strong_roots);
624 }
625 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
626 Management::oops_do(strong_roots);
627 }
628 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
629 JvmtiExport::oops_do(strong_roots);
630 }
631
632 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
633 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
634 }
635
636 // All threads execute the following. A specific chunk of buckets
637 // from the StringTable are the individual tasks.
638 if (weak_roots != NULL) {
639 if (is_par) {
640 StringTable::possibly_parallel_oops_do(weak_roots);
641 } else {
642 StringTable::oops_do(weak_roots);
643 }
644 }
645
646 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
647 if (so & SO_ScavengeCodeCache) {
648 assert(code_roots != NULL, "must supply closure for code cache");
649
650 // We only visit parts of the CodeCache when scavenging.
651 CodeCache::scavenge_root_nmethods_do(code_roots);
652 }
653 if (so & SO_AllCodeCache) {
654 assert(code_roots != NULL, "must supply closure for code cache");
655
656 // CMSCollector uses this to do intermediate-strength collections.
657 // We scan the entire code cache, since CodeCache::do_unloading is not called.
658 CodeCache::blobs_do(code_roots);
659 }
660 // Verify that the code cache contents are not subject to
661 // movement by a scavenging collection.
662 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
663 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
664 }
665 }
666
667 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope,
668 GenerationType type,
669 bool young_gen_as_roots,
670 ScanningOption so,
671 bool only_strong_roots,
672 OopsInGenClosure* not_older_gens,
673 OopsInGenClosure* older_gens,
674 CLDClosure* cld_closure) {
675 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots;
676
677 bool is_moving_collection = false;
678 if (type == YoungGen || is_adjust_phase) {
679 // young collections are always moving
680 is_moving_collection = true;
681 }
682
683 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
684 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
685 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
686
687 process_roots(scope, so,
688 not_older_gens, weak_roots,
689 cld_closure, weak_cld_closure,
690 &mark_code_closure);
691
692 if (young_gen_as_roots) {
693 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
694 if (type == OldGen) {
695 not_older_gens->set_generation(_young_gen);
696 _young_gen->oop_iterate(not_older_gens);
697 }
698 not_older_gens->reset_generation();
699 }
700 }
701 // When collection is parallel, all threads get to cooperate to do
702 // old generation scanning.
703 if (type == YoungGen) {
704 older_gens->set_generation(_old_gen);
705 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
706 older_gens->reset_generation();
707 }
708
709 _process_strong_tasks->all_tasks_completed(scope->n_threads());
710 }
711
712
713 class AlwaysTrueClosure: public BoolObjectClosure {
714 public:
715 bool do_object_b(oop p) { return true; }
716 };
717 static AlwaysTrueClosure always_true;
718
719 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
720 JNIHandles::weak_oops_do(&always_true, root_closure);
721 _young_gen->ref_processor()->weak_oops_do(root_closure);
722 _old_gen->ref_processor()->weak_oops_do(root_closure);
723 }
724
725 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
726 void GenCollectedHeap:: \
727 oop_since_save_marks_iterate(GenerationType gen, \
728 OopClosureType* cur, \
729 OopClosureType* older) { \
730 if (gen == YoungGen) { \
731 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
732 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
733 } else { \
734 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
735 } \
736 }
737
738 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
739
740 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
741
742 bool GenCollectedHeap::no_allocs_since_save_marks() {
743 return _young_gen->no_allocs_since_save_marks() &&
744 _old_gen->no_allocs_since_save_marks();
745 }
746
747 bool GenCollectedHeap::supports_inline_contig_alloc() const {
748 return _young_gen->supports_inline_contig_alloc();
749 }
750
751 HeapWord** GenCollectedHeap::top_addr() const {
752 return _young_gen->top_addr();
753 }
754
755 HeapWord** GenCollectedHeap::end_addr() const {
756 return _young_gen->end_addr();
757 }
758
759 // public collection interfaces
760
761 void GenCollectedHeap::collect(GCCause::Cause cause) {
762 if (should_do_concurrent_full_gc(cause)) {
763 #if INCLUDE_ALL_GCS
764 // Mostly concurrent full collection.
765 collect_mostly_concurrent(cause);
766 #else // INCLUDE_ALL_GCS
767 ShouldNotReachHere();
768 #endif // INCLUDE_ALL_GCS
769 } else if (cause == GCCause::_wb_young_gc) {
770 // Young collection for the WhiteBox API.
771 collect(cause, YoungGen);
772 } else {
773 #ifdef ASSERT
774 if (cause == GCCause::_scavenge_alot) {
775 // Young collection only.
776 collect(cause, YoungGen);
777 } else {
778 // Stop-the-world full collection.
779 collect(cause, OldGen);
780 }
781 #else
782 // Stop-the-world full collection.
783 collect(cause, OldGen);
784 #endif
785 }
786 }
787
788 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
789 // The caller doesn't have the Heap_lock
790 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
791 MutexLocker ml(Heap_lock);
792 collect_locked(cause, max_generation);
793 }
794
795 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
796 // The caller has the Heap_lock
797 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
798 collect_locked(cause, OldGen);
799 }
800
801 // this is the private collection interface
802 // The Heap_lock is expected to be held on entry.
803
804 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
805 // Read the GC count while holding the Heap_lock
806 unsigned int gc_count_before = total_collections();
807 unsigned int full_gc_count_before = total_full_collections();
808 {
809 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
810 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
811 cause, max_generation);
812 VMThread::execute(&op);
813 }
814 }
815
816 #if INCLUDE_ALL_GCS
817 bool GenCollectedHeap::create_cms_collector() {
818
819 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
820 "Unexpected generation kinds");
821 // Skip two header words in the block content verification
822 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
823 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type");
824 CMSCollector* collector =
825 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen,
826 _rem_set->as_CardTableRS(),
827 _gen_policy->as_concurrent_mark_sweep_policy());
828
829 if (collector == NULL || !collector->completed_initialization()) {
830 if (collector) {
831 delete collector; // Be nice in embedded situation
832 }
833 vm_shutdown_during_initialization("Could not create CMS collector");
834 return false;
835 }
836 return true; // success
837 }
838
839 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
840 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
841
842 MutexLocker ml(Heap_lock);
843 // Read the GC counts while holding the Heap_lock
844 unsigned int full_gc_count_before = total_full_collections();
845 unsigned int gc_count_before = total_collections();
846 {
847 MutexUnlocker mu(Heap_lock);
848 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
849 VMThread::execute(&op);
850 }
851 }
852 #endif // INCLUDE_ALL_GCS
853
854 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
855 do_full_collection(clear_all_soft_refs, OldGen);
856 }
857
858 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
859 GenerationType last_generation) {
860 GenerationType local_last_generation;
861 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
862 gc_cause() == GCCause::_gc_locker) {
863 local_last_generation = YoungGen;
864 } else {
865 local_last_generation = last_generation;
866 }
867
868 do_collection(true, // full
869 clear_all_soft_refs, // clear_all_soft_refs
870 0, // size
871 false, // is_tlab
872 local_last_generation); // last_generation
873 // Hack XXX FIX ME !!!
874 // A scavenge may not have been attempted, or may have
875 // been attempted and failed, because the old gen was too full
876 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
877 incremental_collection_will_fail(false /* don't consult_young */)) {
878 if (PrintGCDetails) {
879 gclog_or_tty->print_cr("GC locker: Trying a full collection "
880 "because scavenge failed");
881 }
882 // This time allow the old gen to be collected as well
883 do_collection(true, // full
884 clear_all_soft_refs, // clear_all_soft_refs
885 0, // size
886 false, // is_tlab
887 OldGen); // last_generation
888 }
889 }
890
891 bool GenCollectedHeap::is_in_young(oop p) {
892 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
893 assert(result == _young_gen->is_in_reserved(p),
894 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
895 return result;
896 }
897
898 // Returns "TRUE" iff "p" points into the committed areas of the heap.
899 bool GenCollectedHeap::is_in(const void* p) const {
900 return _young_gen->is_in(p) || _old_gen->is_in(p);
901 }
902
903 #ifdef ASSERT
904 // Don't implement this by using is_in_young(). This method is used
905 // in some cases to check that is_in_young() is correct.
906 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
907 assert(is_in_reserved(p) || p == NULL,
908 "Does not work if address is non-null and outside of the heap");
909 return p < _young_gen->reserved().end() && p != NULL;
910 }
911 #endif
912
913 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
914 NoHeaderExtendedOopClosure no_header_cl(cl);
915 oop_iterate(&no_header_cl);
916 }
917
918 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
919 _young_gen->oop_iterate(cl);
920 _old_gen->oop_iterate(cl);
921 }
922
923 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
924 _young_gen->object_iterate(cl);
925 _old_gen->object_iterate(cl);
926 }
927
928 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
929 _young_gen->safe_object_iterate(cl);
930 _old_gen->safe_object_iterate(cl);
931 }
932
933 Space* GenCollectedHeap::space_containing(const void* addr) const {
934 Space* res = _young_gen->space_containing(addr);
935 if (res != NULL) {
936 return res;
937 }
938 res = _old_gen->space_containing(addr);
939 assert(res != NULL, "Could not find containing space");
940 return res;
941 }
942
943 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
944 assert(is_in_reserved(addr), "block_start of address outside of heap");
945 if (_young_gen->is_in_reserved(addr)) {
946 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
947 return _young_gen->block_start(addr);
948 }
949
950 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
951 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
952 return _old_gen->block_start(addr);
953 }
954
955 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
956 assert(is_in_reserved(addr), "block_size of address outside of heap");
957 if (_young_gen->is_in_reserved(addr)) {
958 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
959 return _young_gen->block_size(addr);
960 }
961
962 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
963 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
964 return _old_gen->block_size(addr);
965 }
966
967 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
968 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
969 assert(block_start(addr) == addr, "addr must be a block start");
970 if (_young_gen->is_in_reserved(addr)) {
971 return _young_gen->block_is_obj(addr);
972 }
973
974 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
975 return _old_gen->block_is_obj(addr);
976 }
977
978 bool GenCollectedHeap::supports_tlab_allocation() const {
979 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
980 return _young_gen->supports_tlab_allocation();
981 }
982
983 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
984 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
985 if (_young_gen->supports_tlab_allocation()) {
986 return _young_gen->tlab_capacity();
987 }
988 return 0;
989 }
990
991 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
992 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
993 if (_young_gen->supports_tlab_allocation()) {
994 return _young_gen->tlab_used();
995 }
996 return 0;
997 }
998
999 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1000 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1001 if (_young_gen->supports_tlab_allocation()) {
1002 return _young_gen->unsafe_max_tlab_alloc();
1003 }
1004 return 0;
1005 }
1006
1007 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1008 bool gc_overhead_limit_was_exceeded;
1009 return collector_policy()->mem_allocate_work(size /* size */,
1010 true /* is_tlab */,
1011 &gc_overhead_limit_was_exceeded);
1012 }
1013
1014 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1015 // from the list headed by "*prev_ptr".
1016 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1017 bool first = true;
1018 size_t min_size = 0; // "first" makes this conceptually infinite.
1019 ScratchBlock **smallest_ptr, *smallest;
1020 ScratchBlock *cur = *prev_ptr;
1021 while (cur) {
1022 assert(*prev_ptr == cur, "just checking");
1023 if (first || cur->num_words < min_size) {
1024 smallest_ptr = prev_ptr;
1025 smallest = cur;
1026 min_size = smallest->num_words;
1027 first = false;
1028 }
1029 prev_ptr = &cur->next;
1030 cur = cur->next;
1031 }
1032 smallest = *smallest_ptr;
1033 *smallest_ptr = smallest->next;
1034 return smallest;
1035 }
1036
1037 // Sort the scratch block list headed by res into decreasing size order,
1038 // and set "res" to the result.
1039 static void sort_scratch_list(ScratchBlock*& list) {
1040 ScratchBlock* sorted = NULL;
1041 ScratchBlock* unsorted = list;
1042 while (unsorted) {
1043 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1044 smallest->next = sorted;
1045 sorted = smallest;
1046 }
1047 list = sorted;
1048 }
1049
1050 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1051 size_t max_alloc_words) {
1052 ScratchBlock* res = NULL;
1053 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1054 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1055 sort_scratch_list(res);
1056 return res;
1057 }
1058
1059 void GenCollectedHeap::release_scratch() {
1060 _young_gen->reset_scratch();
1061 _old_gen->reset_scratch();
1062 }
1063
1064 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1065 void do_generation(Generation* gen) {
1066 gen->prepare_for_verify();
1067 }
1068 };
1069
1070 void GenCollectedHeap::prepare_for_verify() {
1071 ensure_parsability(false); // no need to retire TLABs
1072 GenPrepareForVerifyClosure blk;
1073 generation_iterate(&blk, false);
1074 }
1075
1076 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1077 bool old_to_young) {
1078 if (old_to_young) {
1079 cl->do_generation(_old_gen);
1080 cl->do_generation(_young_gen);
1081 } else {
1082 cl->do_generation(_young_gen);
1083 cl->do_generation(_old_gen);
1084 }
1085 }
1086
1087 bool GenCollectedHeap::is_maximal_no_gc() const {
1088 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1089 }
1090
1091 void GenCollectedHeap::save_marks() {
1092 _young_gen->save_marks();
1093 _old_gen->save_marks();
1094 }
1095
1096 GenCollectedHeap* GenCollectedHeap::heap() {
1097 CollectedHeap* heap = Universe::heap();
1098 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1099 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
1100 return (GenCollectedHeap*)heap;
1101 }
1102
1103 void GenCollectedHeap::prepare_for_compaction() {
1104 // Start by compacting into same gen.
1105 CompactPoint cp(_old_gen);
1106 _old_gen->prepare_for_compaction(&cp);
1107 _young_gen->prepare_for_compaction(&cp);
1108 }
1109
1110 GCStats* GenCollectedHeap::gc_stats(Generation* gen) const {
1111 return gen->gc_stats();
1112 }
1113
1114 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1115 if (!silent) {
1116 gclog_or_tty->print("%s", _old_gen->name());
1117 gclog_or_tty->print(" ");
1118 }
1119 _old_gen->verify();
1120
1121 if (!silent) {
1122 gclog_or_tty->print("%s", _young_gen->name());
1123 gclog_or_tty->print(" ");
1124 }
1125 _young_gen->verify();
1126
1127 if (!silent) {
1128 gclog_or_tty->print("remset ");
1129 }
1130 rem_set()->verify();
1131 }
1132
1133 void GenCollectedHeap::print_on(outputStream* st) const {
1134 _young_gen->print_on(st);
1135 _old_gen->print_on(st);
1136 MetaspaceAux::print_on(st);
1137 }
1138
1139 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1140 if (workers() != NULL) {
1141 workers()->threads_do(tc);
1142 }
1143 #if INCLUDE_ALL_GCS
1144 if (UseConcMarkSweepGC) {
1145 ConcurrentMarkSweepThread::threads_do(tc);
1146 }
1147 #endif // INCLUDE_ALL_GCS
1148 }
1149
1150 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1151 #if INCLUDE_ALL_GCS
1152 if (UseConcMarkSweepGC) {
1153 workers()->print_worker_threads_on(st);
1154 ConcurrentMarkSweepThread::print_all_on(st);
1155 }
1156 #endif // INCLUDE_ALL_GCS
1157 }
1158
1159 void GenCollectedHeap::print_on_error(outputStream* st) const {
1160 this->CollectedHeap::print_on_error(st);
1161
1162 #if INCLUDE_ALL_GCS
1163 if (UseConcMarkSweepGC) {
1164 st->cr();
1165 CMSCollector::print_on_error(st);
1166 }
1167 #endif // INCLUDE_ALL_GCS
1168 }
1169
1170 void GenCollectedHeap::print_tracing_info() const {
1171 if (TraceYoungGenTime) {
1172 _young_gen->print_summary_info();
1173 }
1174 if (TraceOldGenTime) {
1175 _old_gen->print_summary_info();
1176 }
1177 }
1178
1179 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1180 if (PrintGCDetails && Verbose) {
1181 gclog_or_tty->print(" " SIZE_FORMAT
1182 "->" SIZE_FORMAT
1183 "(" SIZE_FORMAT ")",
1184 prev_used, used(), capacity());
1185 } else {
1186 gclog_or_tty->print(" " SIZE_FORMAT "K"
1187 "->" SIZE_FORMAT "K"
1188 "(" SIZE_FORMAT "K)",
1189 prev_used / K, used() / K, capacity() / K);
1190 }
1191 }
1192
1193 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1194 private:
1195 bool _full;
1196 public:
1197 void do_generation(Generation* gen) {
1198 gen->gc_prologue(_full);
1199 }
1200 GenGCPrologueClosure(bool full) : _full(full) {};
1201 };
1202
1203 void GenCollectedHeap::gc_prologue(bool full) {
1204 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1205
1206 always_do_update_barrier = false;
1207 // Fill TLAB's and such
1208 CollectedHeap::accumulate_statistics_all_tlabs();
1209 ensure_parsability(true); // retire TLABs
1210
1211 // Walk generations
1212 GenGCPrologueClosure blk(full);
1213 generation_iterate(&blk, false); // not old-to-young.
1214 };
1215
1216 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1217 private:
1218 bool _full;
1219 public:
1220 void do_generation(Generation* gen) {
1221 gen->gc_epilogue(_full);
1222 }
1223 GenGCEpilogueClosure(bool full) : _full(full) {};
1224 };
1225
1226 void GenCollectedHeap::gc_epilogue(bool full) {
1227 #ifdef COMPILER2
1228 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1229 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1230 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1231 #endif /* COMPILER2 */
1232
1233 resize_all_tlabs();
1234
1235 GenGCEpilogueClosure blk(full);
1236 generation_iterate(&blk, false); // not old-to-young.
1237
1238 if (!CleanChunkPoolAsync) {
1239 Chunk::clean_chunk_pool();
1240 }
1241
1242 MetaspaceCounters::update_performance_counters();
1243 CompressedClassSpaceCounters::update_performance_counters();
1244
1245 always_do_update_barrier = UseConcMarkSweepGC;
1246 };
1247
1248 #ifndef PRODUCT
1249 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1250 private:
1251 public:
1252 void do_generation(Generation* gen) {
1253 gen->record_spaces_top();
1254 }
1255 };
1256
1257 void GenCollectedHeap::record_gen_tops_before_GC() {
1258 if (ZapUnusedHeapArea) {
1259 GenGCSaveTopsBeforeGCClosure blk;
1260 generation_iterate(&blk, false); // not old-to-young.
1261 }
1262 }
1263 #endif // not PRODUCT
1264
1265 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1266 public:
1267 void do_generation(Generation* gen) {
1268 gen->ensure_parsability();
1269 }
1270 };
1271
1272 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1273 CollectedHeap::ensure_parsability(retire_tlabs);
1274 GenEnsureParsabilityClosure ep_cl;
1275 generation_iterate(&ep_cl, false);
1276 }
1277
1278 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1279 oop obj,
1280 size_t obj_size) {
1281 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1282 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1283 HeapWord* result = NULL;
1284
1285 result = old_gen->expand_and_allocate(obj_size, false);
1286
1287 if (result != NULL) {
1288 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1289 }
1290 return oop(result);
1291 }
1292
1293 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1294 jlong _time; // in ms
1295 jlong _now; // in ms
1296
1297 public:
1298 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1299
1300 jlong time() { return _time; }
1301
1302 void do_generation(Generation* gen) {
1303 _time = MIN2(_time, gen->time_of_last_gc(_now));
1304 }
1305 };
1306
1307 jlong GenCollectedHeap::millis_since_last_gc() {
1308 // We need a monotonically non-decreasing time in ms but
1309 // os::javaTimeMillis() does not guarantee monotonicity.
1310 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1311 GenTimeOfLastGCClosure tolgc_cl(now);
1312 // iterate over generations getting the oldest
1313 // time that a generation was collected
1314 generation_iterate(&tolgc_cl, false);
1315
1316 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1317 // provided the underlying platform provides such a time source
1318 // (and it is bug free). So we still have to guard against getting
1319 // back a time later than 'now'.
1320 jlong retVal = now - tolgc_cl.time();
1321 if (retVal < 0) {
1322 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1323 return 0;
1324 }
1325 return retVal;
1326 }