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_implementation/shared/collectorCounters.hpp"
32 #include "gc_implementation/shared/gcTrace.hpp"
33 #include "gc_implementation/shared/gcTraceTime.hpp"
34 #include "gc_implementation/shared/vmGCOperations.hpp"
35 #include "gc_interface/collectedHeap.inline.hpp"
36 #include "memory/filemap.hpp"
37 #include "memory/gcLocker.inline.hpp"
38 #include "memory/genCollectedHeap.hpp"
39 #include "memory/genOopClosures.inline.hpp"
40 #include "memory/generationSpec.hpp"
41 #include "memory/resourceArea.hpp"
42 #include "memory/sharedHeap.hpp"
43 #include "memory/space.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "runtime/biasedLocking.hpp"
46 #include "runtime/fprofiler.hpp"
47 #include "runtime/handles.hpp"
48 #include "runtime/handles.inline.hpp"
49 #include "runtime/java.hpp"
50 #include "runtime/vmThread.hpp"
51 #include "services/management.hpp"
52 #include "services/memoryService.hpp"
53 #include "utilities/vmError.hpp"
54 #include "utilities/workgroup.hpp"
55 #include "utilities/macros.hpp"
56 #if INCLUDE_ALL_GCS
57 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
58 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
59 #endif // INCLUDE_ALL_GCS
60
61 GenCollectedHeap* GenCollectedHeap::_gch;
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 SharedHeap(),
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 FlexibleWorkGang("GC Thread", ParallelGCThreads,
90 /* are_GC_task_threads */true,
91 /* are_ConcurrentGC_threads */false);
92 _workers->initialize_workers();
93 } else {
94 _workers = NULL;
95 }
96 }
97
98 jint GenCollectedHeap::initialize() {
99 CollectedHeap::pre_initialize();
100
101 _n_gens = gen_policy()->number_of_generations();
102 assert(_n_gens == 2, "There is no support for more than two generations");
103
104 // While there are no constraints in the GC code that HeapWordSize
105 // be any particular value, there are multiple other areas in the
106 // system which believe this to be true (e.g. oop->object_size in some
107 // cases incorrectly returns the size in wordSize units rather than
108 // HeapWordSize).
109 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
110
111 // Allocate space for the heap.
112
113 char* heap_address;
114 ReservedSpace heap_rs;
115
116 size_t heap_alignment = collector_policy()->heap_alignment();
117
118 heap_address = allocate(heap_alignment, &heap_rs);
119
120 if (!heap_rs.is_reserved()) {
121 vm_shutdown_during_initialization(
122 "Could not reserve enough space for object heap");
123 return JNI_ENOMEM;
124 }
125
126 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
127
128 _rem_set = collector_policy()->create_rem_set(reserved_region());
129 set_barrier_set(rem_set()->bs());
130
131 _gch = this;
132
133 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
134 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set());
135 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
136
137 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
138 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set());
139 clear_incremental_collection_failed();
140
141 #if INCLUDE_ALL_GCS
142 // If we are running CMS, create the collector responsible
143 // for collecting the CMS generations.
144 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
145 bool success = create_cms_collector();
146 if (!success) return JNI_ENOMEM;
147 }
148 #endif // INCLUDE_ALL_GCS
149
150 return JNI_OK;
151 }
152
153 char* GenCollectedHeap::allocate(size_t alignment,
154 ReservedSpace* heap_rs){
155 // Now figure out the total size.
156 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
157 assert(alignment % pageSize == 0, "Must be");
158
159 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
160 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
161
162 // Check for overflow.
163 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
164 if (total_reserved < young_spec->max_size()) {
165 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
166 "the maximum representable size");
167 }
168 assert(total_reserved % alignment == 0,
169 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
170 SIZE_FORMAT, total_reserved, alignment));
171
172 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
173 return heap_rs->base();
174 }
175
176 void GenCollectedHeap::post_initialize() {
177 CollectedHeap::post_initialize();
178 ref_processing_init();
179 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
180 guarantee(policy->is_generation_policy(), "Illegal policy type");
181 assert((_young_gen->kind() == Generation::DefNew) ||
182 (_young_gen->kind() == Generation::ParNew),
183 "Wrong youngest generation type");
184 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
185
186 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
187 _old_gen->kind() == Generation::MarkSweepCompact,
188 "Wrong generation kind");
189
190 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
191 _old_gen->capacity(),
192 def_new_gen->from()->capacity());
193 policy->initialize_gc_policy_counters();
194 }
195
196 void GenCollectedHeap::ref_processing_init() {
197 _young_gen->ref_processor_init();
198 _old_gen->ref_processor_init();
199 }
200
201 size_t GenCollectedHeap::capacity() const {
202 return _young_gen->capacity() + _old_gen->capacity();
203 }
204
205 size_t GenCollectedHeap::used() const {
206 return _young_gen->used() + _old_gen->used();
207 }
208
209 // Save the "used_region" for generations level and lower.
210 void GenCollectedHeap::save_used_regions(int level) {
211 assert(level >= 0, "Illegal level parameter");
212 assert(level < _n_gens, "Illegal level parameter");
213 if (level == 1) {
214 _old_gen->save_used_region();
215 }
216 _young_gen->save_used_region();
217 }
218
219 size_t GenCollectedHeap::max_capacity() const {
220 return _young_gen->max_capacity() + _old_gen->max_capacity();
221 }
222
223 // Update the _full_collections_completed counter
224 // at the end of a stop-world full GC.
225 unsigned int GenCollectedHeap::update_full_collections_completed() {
226 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
227 assert(_full_collections_completed <= _total_full_collections,
228 "Can't complete more collections than were started");
229 _full_collections_completed = _total_full_collections;
230 ml.notify_all();
231 return _full_collections_completed;
232 }
233
234 // Update the _full_collections_completed counter, as appropriate,
235 // at the end of a concurrent GC cycle. Note the conditional update
236 // below to allow this method to be called by a concurrent collector
237 // without synchronizing in any manner with the VM thread (which
238 // may already have initiated a STW full collection "concurrently").
239 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
240 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
241 assert((_full_collections_completed <= _total_full_collections) &&
242 (count <= _total_full_collections),
243 "Can't complete more collections than were started");
244 if (count > _full_collections_completed) {
245 _full_collections_completed = count;
246 ml.notify_all();
247 }
248 return _full_collections_completed;
249 }
250
251
252 #ifndef PRODUCT
253 // Override of memory state checking method in CollectedHeap:
254 // Some collectors (CMS for example) can't have badHeapWordVal written
255 // in the first two words of an object. (For instance , in the case of
256 // CMS these words hold state used to synchronize between certain
257 // (concurrent) GC steps and direct allocating mutators.)
258 // The skip_header_HeapWords() method below, allows us to skip
259 // over the requisite number of HeapWord's. Note that (for
260 // generational collectors) this means that those many words are
261 // skipped in each object, irrespective of the generation in which
262 // that object lives. The resultant loss of precision seems to be
263 // harmless and the pain of avoiding that imprecision appears somewhat
264 // higher than we are prepared to pay for such rudimentary debugging
265 // support.
266 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
267 size_t size) {
268 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
269 // We are asked to check a size in HeapWords,
270 // but the memory is mangled in juint words.
271 juint* start = (juint*) (addr + skip_header_HeapWords());
272 juint* end = (juint*) (addr + size);
273 for (juint* slot = start; slot < end; slot += 1) {
274 assert(*slot == badHeapWordVal,
275 "Found non badHeapWordValue in pre-allocation check");
276 }
277 }
278 }
279 #endif
280
281 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
282 bool is_tlab,
283 bool first_only) {
284 HeapWord* res = NULL;
285
286 if (_young_gen->should_allocate(size, is_tlab)) {
287 res = _young_gen->allocate(size, is_tlab);
288 if (res != NULL || first_only) {
289 return res;
290 }
291 }
292
293 if (_old_gen->should_allocate(size, is_tlab)) {
294 res = _old_gen->allocate(size, is_tlab);
295 }
296
297 return res;
298 }
299
300 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
301 bool* gc_overhead_limit_was_exceeded) {
302 return collector_policy()->mem_allocate_work(size,
303 false /* is_tlab */,
304 gc_overhead_limit_was_exceeded);
305 }
306
307 bool GenCollectedHeap::must_clear_all_soft_refs() {
308 return _gc_cause == GCCause::_last_ditch_collection;
309 }
310
311 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
312 return UseConcMarkSweepGC &&
313 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
314 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
315 }
316
317 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
318 bool is_tlab, bool run_verification, bool clear_soft_refs,
319 bool restore_marks_for_biased_locking) {
320 // Timer for individual generations. Last argument is false: no CR
321 // FIXME: We should try to start the timing earlier to cover more of the GC pause
322 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
323 // so we can assume here that the next GC id is what we want.
324 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
325 TraceCollectorStats tcs(gen->counters());
326 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
327
328 size_t prev_used = gen->used();
329 gen->stat_record()->invocations++;
330 gen->stat_record()->accumulated_time.start();
331
332 // Must be done anew before each collection because
333 // a previous collection will do mangling and will
334 // change top of some spaces.
335 record_gen_tops_before_GC();
336
337 if (PrintGC && Verbose) {
338 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
339 gen->level(),
340 gen->stat_record()->invocations,
341 size * HeapWordSize);
342 }
343
344 if (run_verification && VerifyBeforeGC) {
345 HandleMark hm; // Discard invalid handles created during verification
346 Universe::verify(" VerifyBeforeGC:");
347 }
348 COMPILER2_PRESENT(DerivedPointerTable::clear());
349
350 if (restore_marks_for_biased_locking) {
351 // We perform this mark word preservation work lazily
352 // because it's only at this point that we know whether we
353 // absolutely have to do it; we want to avoid doing it for
354 // scavenge-only collections where it's unnecessary
355 BiasedLocking::preserve_marks();
356 }
357
358 // Do collection work
359 {
360 // Note on ref discovery: For what appear to be historical reasons,
361 // GCH enables and disabled (by enqueing) refs discovery.
362 // In the future this should be moved into the generation's
363 // collect method so that ref discovery and enqueueing concerns
364 // are local to a generation. The collect method could return
365 // an appropriate indication in the case that notification on
366 // the ref lock was needed. This will make the treatment of
367 // weak refs more uniform (and indeed remove such concerns
368 // from GCH). XXX
369
370 HandleMark hm; // Discard invalid handles created during gc
371 save_marks(); // save marks for all gens
372 // We want to discover references, but not process them yet.
373 // This mode is disabled in process_discovered_references if the
374 // generation does some collection work, or in
375 // enqueue_discovered_references if the generation returns
376 // without doing any work.
377 ReferenceProcessor* rp = gen->ref_processor();
378 // If the discovery of ("weak") refs in this generation is
379 // atomic wrt other collectors in this configuration, we
380 // are guaranteed to have empty discovered ref lists.
381 if (rp->discovery_is_atomic()) {
382 rp->enable_discovery();
383 rp->setup_policy(clear_soft_refs);
384 } else {
385 // collect() below will enable discovery as appropriate
386 }
387 gen->collect(full, clear_soft_refs, size, is_tlab);
388 if (!rp->enqueuing_is_done()) {
389 rp->enqueue_discovered_references();
390 } else {
391 rp->set_enqueuing_is_done(false);
392 }
393 rp->verify_no_references_recorded();
394 }
395
396 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
397
398 gen->stat_record()->accumulated_time.stop();
399
400 update_gc_stats(gen->level(), full);
401
402 if (run_verification && VerifyAfterGC) {
403 HandleMark hm; // Discard invalid handles created during verification
404 Universe::verify(" VerifyAfterGC:");
405 }
406
407 if (PrintGCDetails) {
408 gclog_or_tty->print(":");
409 gen->print_heap_change(prev_used);
410 }
411 }
412
413 void GenCollectedHeap::do_collection(bool full,
414 bool clear_all_soft_refs,
415 size_t size,
416 bool is_tlab,
417 int max_level) {
418 ResourceMark rm;
419 DEBUG_ONLY(Thread* my_thread = Thread::current();)
420
421 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
422 assert(my_thread->is_VM_thread() ||
423 my_thread->is_ConcurrentGC_thread(),
424 "incorrect thread type capability");
425 assert(Heap_lock->is_locked(),
426 "the requesting thread should have the Heap_lock");
427 guarantee(!is_gc_active(), "collection is not reentrant");
428 assert(max_level < n_gens(), "sanity check");
429
430 if (GC_locker::check_active_before_gc()) {
431 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
432 }
433
434 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
435 collector_policy()->should_clear_all_soft_refs();
436
437 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
438
439 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
440
441 print_heap_before_gc();
442
443 {
444 FlagSetting fl(_is_gc_active, true);
445
446 bool complete = full && (max_level == (n_gens()-1));
447 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
448 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
449 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
450 // so we can assume here that the next GC id is what we want.
451 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
452
453 gc_prologue(complete);
454 increment_total_collections(complete);
455
456 size_t gch_prev_used = used();
457 bool run_verification = total_collections() >= VerifyGCStartAt;
458
459 bool prepared_for_verification = false;
460 int max_level_collected = 0;
461 bool old_collects_young = (max_level == 1) &&
462 full &&
463 _old_gen->full_collects_younger_generations();
464 if (!old_collects_young &&
465 _young_gen->should_collect(full, size, is_tlab)) {
466 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
467 prepare_for_verify();
468 prepared_for_verification = true;
469 }
470
471 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
472 collect_generation(_young_gen,
473 full,
474 size,
475 is_tlab,
476 run_verification && VerifyGCLevel <= 0,
477 do_clear_all_soft_refs,
478 false);
479
480 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
481 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
482 // Allocation request was met by young GC.
483 size = 0;
484 }
485 }
486
487 bool must_restore_marks_for_biased_locking = false;
488
489 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
490 if (!complete) {
491 // The full_collections increment was missed above.
492 increment_total_full_collections();
493 }
494
495 pre_full_gc_dump(NULL); // do any pre full gc dumps
496
497 if (!prepared_for_verification && run_verification &&
498 VerifyGCLevel <= 1 && VerifyBeforeGC) {
499 prepare_for_verify();
500 }
501
502 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
503 collect_generation(_old_gen,
504 full,
505 size,
506 is_tlab,
507 run_verification && VerifyGCLevel <= 1,
508 do_clear_all_soft_refs,
509 true);
510
511 must_restore_marks_for_biased_locking = true;
512 max_level_collected = 1;
513 }
514
515 // Update "complete" boolean wrt what actually transpired --
516 // for instance, a promotion failure could have led to
517 // a whole heap collection.
518 complete = complete || (max_level_collected == n_gens() - 1);
519
520 if (complete) { // We did a "major" collection
521 // FIXME: See comment at pre_full_gc_dump call
522 post_full_gc_dump(NULL); // do any post full gc dumps
523 }
524
525 if (PrintGCDetails) {
526 print_heap_change(gch_prev_used);
527
528 // Print metaspace info for full GC with PrintGCDetails flag.
529 if (complete) {
530 MetaspaceAux::print_metaspace_change(metadata_prev_used);
531 }
532 }
533
534 // Adjust generation sizes.
535 if (max_level_collected == 1) {
536 _old_gen->compute_new_size();
537 }
538 _young_gen->compute_new_size();
539
540 if (complete) {
541 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
542 ClassLoaderDataGraph::purge();
543 MetaspaceAux::verify_metrics();
544 // Resize the metaspace capacity after full collections
545 MetaspaceGC::compute_new_size();
546 update_full_collections_completed();
547 }
548
549 // Track memory usage and detect low memory after GC finishes
550 MemoryService::track_memory_usage();
551
552 gc_epilogue(complete);
553
554 if (must_restore_marks_for_biased_locking) {
555 BiasedLocking::restore_marks();
556 }
557 }
558
559 print_heap_after_gc();
560
561 #ifdef TRACESPINNING
562 ParallelTaskTerminator::print_termination_counts();
563 #endif
564 }
565
566 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
567 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
568 }
569
570 void GenCollectedHeap::set_par_threads(uint t) {
571 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
572 CollectedHeap::set_par_threads(t);
573 set_n_termination(t);
574 }
575
576 void GenCollectedHeap::set_n_termination(uint t) {
577 _process_strong_tasks->set_n_threads(t);
578 }
579
580 #ifdef ASSERT
581 class AssertNonScavengableClosure: public OopClosure {
582 public:
583 virtual void do_oop(oop* p) {
584 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
585 "Referent should not be scavengable."); }
586 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
587 };
588 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
589 #endif
590
591 void GenCollectedHeap::process_roots(bool activate_scope,
592 ScanningOption so,
593 OopClosure* strong_roots,
594 OopClosure* weak_roots,
595 CLDClosure* strong_cld_closure,
596 CLDClosure* weak_cld_closure,
597 CodeBlobClosure* code_roots) {
598 StrongRootsScope srs(this, activate_scope);
599
600 // General roots.
601 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
602 assert(code_roots != NULL, "code root closure should always be set");
603 // _n_termination for _process_strong_tasks should be set up stream
604 // in a method not running in a GC worker. Otherwise the GC worker
605 // could be trying to change the termination condition while the task
606 // is executing in another GC worker.
607
608 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
609 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
610 }
611
612 // Some CLDs contained in the thread frames should be considered strong.
613 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
614 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
615 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
616 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
617
618 bool is_par = n_par_threads() > 0;
619 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
620
621 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
622 Universe::oops_do(strong_roots);
623 }
624 // Global (strong) JNI handles
625 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
626 JNIHandles::oops_do(strong_roots);
627 }
628
629 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
630 ObjectSynchronizer::oops_do(strong_roots);
631 }
632 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
633 FlatProfiler::oops_do(strong_roots);
634 }
635 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
636 Management::oops_do(strong_roots);
637 }
638 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
639 JvmtiExport::oops_do(strong_roots);
640 }
641
642 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
643 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
644 }
645
646 // All threads execute the following. A specific chunk of buckets
647 // from the StringTable are the individual tasks.
648 if (weak_roots != NULL) {
649 if (CollectedHeap::use_parallel_gc_threads()) {
650 StringTable::possibly_parallel_oops_do(weak_roots);
651 } else {
652 StringTable::oops_do(weak_roots);
653 }
654 }
655
656 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
657 if (so & SO_ScavengeCodeCache) {
658 assert(code_roots != NULL, "must supply closure for code cache");
659
660 // We only visit parts of the CodeCache when scavenging.
661 CodeCache::scavenge_root_nmethods_do(code_roots);
662 }
663 if (so & SO_AllCodeCache) {
664 assert(code_roots != NULL, "must supply closure for code cache");
665
666 // CMSCollector uses this to do intermediate-strength collections.
667 // We scan the entire code cache, since CodeCache::do_unloading is not called.
668 CodeCache::blobs_do(code_roots);
669 }
670 // Verify that the code cache contents are not subject to
671 // movement by a scavenging collection.
672 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
673 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
674 }
675
676 }
677
678 void GenCollectedHeap::gen_process_roots(int level,
679 bool younger_gens_as_roots,
680 bool activate_scope,
681 ScanningOption so,
682 bool only_strong_roots,
683 OopsInGenClosure* not_older_gens,
684 OopsInGenClosure* older_gens,
685 CLDClosure* cld_closure) {
686 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
687
688 bool is_moving_collection = false;
689 if (level == 0 || is_adjust_phase) {
690 // young collections are always moving
691 is_moving_collection = true;
692 }
693
694 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
695 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
696 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
697
698 process_roots(activate_scope, so,
699 not_older_gens, weak_roots,
700 cld_closure, weak_cld_closure,
701 &mark_code_closure);
702
703 if (younger_gens_as_roots) {
704 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
705 if (level == 1) {
706 not_older_gens->set_generation(_young_gen);
707 _young_gen->oop_iterate(not_older_gens);
708 }
709 not_older_gens->reset_generation();
710 }
711 }
712 // When collection is parallel, all threads get to cooperate to do
713 // older-gen scanning.
714 if (level == 0) {
715 older_gens->set_generation(_old_gen);
716 rem_set()->younger_refs_iterate(_old_gen, older_gens);
717 older_gens->reset_generation();
718 }
719
720 _process_strong_tasks->all_tasks_completed();
721 }
722
723
724 class AlwaysTrueClosure: public BoolObjectClosure {
725 public:
726 bool do_object_b(oop p) { return true; }
727 };
728 static AlwaysTrueClosure always_true;
729
730 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
731 JNIHandles::weak_oops_do(&always_true, root_closure);
732 _young_gen->ref_processor()->weak_oops_do(root_closure);
733 _old_gen->ref_processor()->weak_oops_do(root_closure);
734 }
735
736 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
737 void GenCollectedHeap:: \
738 oop_since_save_marks_iterate(int level, \
739 OopClosureType* cur, \
740 OopClosureType* older) { \
741 if (level == 0) { \
742 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
743 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
744 } else { \
745 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
746 } \
747 }
748
749 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
750
751 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
752
753 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
754 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) {
755 return false;
756 }
757 return _old_gen->no_allocs_since_save_marks();
758 }
759
760 bool GenCollectedHeap::supports_inline_contig_alloc() const {
761 return _young_gen->supports_inline_contig_alloc();
762 }
763
764 HeapWord** GenCollectedHeap::top_addr() const {
765 return _young_gen->top_addr();
766 }
767
768 HeapWord** GenCollectedHeap::end_addr() const {
769 return _young_gen->end_addr();
770 }
771
772 // public collection interfaces
773
774 void GenCollectedHeap::collect(GCCause::Cause cause) {
775 if (should_do_concurrent_full_gc(cause)) {
776 #if INCLUDE_ALL_GCS
777 // mostly concurrent full collection
778 collect_mostly_concurrent(cause);
779 #else // INCLUDE_ALL_GCS
780 ShouldNotReachHere();
781 #endif // INCLUDE_ALL_GCS
782 } else if (cause == GCCause::_wb_young_gc) {
783 // minor collection for WhiteBox API
784 collect(cause, 0);
785 } else {
786 #ifdef ASSERT
787 if (cause == GCCause::_scavenge_alot) {
788 // minor collection only
789 collect(cause, 0);
790 } else {
791 // Stop-the-world full collection
792 collect(cause, n_gens() - 1);
793 }
794 #else
795 // Stop-the-world full collection
796 collect(cause, n_gens() - 1);
797 #endif
798 }
799 }
800
801 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
802 // The caller doesn't have the Heap_lock
803 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
804 MutexLocker ml(Heap_lock);
805 collect_locked(cause, max_level);
806 }
807
808 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
809 // The caller has the Heap_lock
810 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
811 collect_locked(cause, n_gens() - 1);
812 }
813
814 // this is the private collection interface
815 // The Heap_lock is expected to be held on entry.
816
817 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
818 // Read the GC count while holding the Heap_lock
819 unsigned int gc_count_before = total_collections();
820 unsigned int full_gc_count_before = total_full_collections();
821 {
822 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
823 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
824 cause, max_level);
825 VMThread::execute(&op);
826 }
827 }
828
829 #if INCLUDE_ALL_GCS
830 bool GenCollectedHeap::create_cms_collector() {
831
832 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
833 "Unexpected generation kinds");
834 // Skip two header words in the block content verification
835 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
836 CMSCollector* collector = new CMSCollector(
837 (ConcurrentMarkSweepGeneration*)_old_gen,
838 _rem_set->as_CardTableRS(),
839 (ConcurrentMarkSweepPolicy*) collector_policy());
840
841 if (collector == NULL || !collector->completed_initialization()) {
842 if (collector) {
843 delete collector; // Be nice in embedded situation
844 }
845 vm_shutdown_during_initialization("Could not create CMS collector");
846 return false;
847 }
848 return true; // success
849 }
850
851 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
852 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
853
854 MutexLocker ml(Heap_lock);
855 // Read the GC counts while holding the Heap_lock
856 unsigned int full_gc_count_before = total_full_collections();
857 unsigned int gc_count_before = total_collections();
858 {
859 MutexUnlocker mu(Heap_lock);
860 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
861 VMThread::execute(&op);
862 }
863 }
864 #endif // INCLUDE_ALL_GCS
865
866 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
867 do_full_collection(clear_all_soft_refs, _n_gens - 1);
868 }
869
870 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
871 int max_level) {
872 int local_max_level;
873 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
874 gc_cause() == GCCause::_gc_locker) {
875 local_max_level = 0;
876 } else {
877 local_max_level = max_level;
878 }
879
880 do_collection(true /* full */,
881 clear_all_soft_refs /* clear_all_soft_refs */,
882 0 /* size */,
883 false /* is_tlab */,
884 local_max_level /* max_level */);
885 // Hack XXX FIX ME !!!
886 // A scavenge may not have been attempted, or may have
887 // been attempted and failed, because the old gen was too full
888 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
889 incremental_collection_will_fail(false /* don't consult_young */)) {
890 if (PrintGCDetails) {
891 gclog_or_tty->print_cr("GC locker: Trying a full collection "
892 "because scavenge failed");
893 }
894 // This time allow the old gen to be collected as well
895 do_collection(true /* full */,
896 clear_all_soft_refs /* clear_all_soft_refs */,
897 0 /* size */,
898 false /* is_tlab */,
899 n_gens() - 1 /* max_level */);
900 }
901 }
902
903 bool GenCollectedHeap::is_in_young(oop p) {
904 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
905 assert(result == _young_gen->is_in_reserved(p),
906 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
907 return result;
908 }
909
910 // Returns "TRUE" iff "p" points into the committed areas of the heap.
911 bool GenCollectedHeap::is_in(const void* p) const {
912 #ifndef ASSERT
913 guarantee(VerifyBeforeGC ||
914 VerifyDuringGC ||
915 VerifyBeforeExit ||
916 VerifyDuringStartup ||
917 PrintAssembly ||
918 tty->count() != 0 || // already printing
919 VerifyAfterGC ||
920 VMError::fatal_error_in_progress(), "too expensive");
921
922 #endif
923 return _young_gen->is_in(p) || _old_gen->is_in(p);
924 }
925
926 #ifdef ASSERT
927 // Don't implement this by using is_in_young(). This method is used
928 // in some cases to check that is_in_young() is correct.
929 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
930 assert(is_in_reserved(p) || p == NULL,
931 "Does not work if address is non-null and outside of the heap");
932 return p < _young_gen->reserved().end() && p != NULL;
933 }
934 #endif
935
936 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
937 NoHeaderExtendedOopClosure no_header_cl(cl);
938 oop_iterate(&no_header_cl);
939 }
940
941 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
942 _young_gen->oop_iterate(cl);
943 _old_gen->oop_iterate(cl);
944 }
945
946 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
947 _young_gen->object_iterate(cl);
948 _old_gen->object_iterate(cl);
949 }
950
951 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
952 _young_gen->safe_object_iterate(cl);
953 _old_gen->safe_object_iterate(cl);
954 }
955
956 Space* GenCollectedHeap::space_containing(const void* addr) const {
957 Space* res = _young_gen->space_containing(addr);
958 if (res != NULL) {
959 return res;
960 }
961 res = _old_gen->space_containing(addr);
962 assert(res != NULL, "Could not find containing space");
963 return res;
964 }
965
966 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
967 assert(is_in_reserved(addr), "block_start of address outside of heap");
968 if (_young_gen->is_in_reserved(addr)) {
969 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
970 return _young_gen->block_start(addr);
971 }
972
973 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
974 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
975 return _old_gen->block_start(addr);
976 }
977
978 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
979 assert(is_in_reserved(addr), "block_size of address outside of heap");
980 if (_young_gen->is_in_reserved(addr)) {
981 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
982 return _young_gen->block_size(addr);
983 }
984
985 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
986 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
987 return _old_gen->block_size(addr);
988 }
989
990 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
991 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
992 assert(block_start(addr) == addr, "addr must be a block start");
993 if (_young_gen->is_in_reserved(addr)) {
994 return _young_gen->block_is_obj(addr);
995 }
996
997 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
998 return _old_gen->block_is_obj(addr);
999 }
1000
1001 bool GenCollectedHeap::supports_tlab_allocation() const {
1002 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1003 return _young_gen->supports_tlab_allocation();
1004 }
1005
1006 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1007 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1008 if (_young_gen->supports_tlab_allocation()) {
1009 return _young_gen->tlab_capacity();
1010 }
1011 return 0;
1012 }
1013
1014 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1015 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1016 if (_young_gen->supports_tlab_allocation()) {
1017 return _young_gen->tlab_used();
1018 }
1019 return 0;
1020 }
1021
1022 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1023 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1024 if (_young_gen->supports_tlab_allocation()) {
1025 return _young_gen->unsafe_max_tlab_alloc();
1026 }
1027 return 0;
1028 }
1029
1030 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1031 bool gc_overhead_limit_was_exceeded;
1032 return collector_policy()->mem_allocate_work(size /* size */,
1033 true /* is_tlab */,
1034 &gc_overhead_limit_was_exceeded);
1035 }
1036
1037 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1038 // from the list headed by "*prev_ptr".
1039 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1040 bool first = true;
1041 size_t min_size = 0; // "first" makes this conceptually infinite.
1042 ScratchBlock **smallest_ptr, *smallest;
1043 ScratchBlock *cur = *prev_ptr;
1044 while (cur) {
1045 assert(*prev_ptr == cur, "just checking");
1046 if (first || cur->num_words < min_size) {
1047 smallest_ptr = prev_ptr;
1048 smallest = cur;
1049 min_size = smallest->num_words;
1050 first = false;
1051 }
1052 prev_ptr = &cur->next;
1053 cur = cur->next;
1054 }
1055 smallest = *smallest_ptr;
1056 *smallest_ptr = smallest->next;
1057 return smallest;
1058 }
1059
1060 // Sort the scratch block list headed by res into decreasing size order,
1061 // and set "res" to the result.
1062 static void sort_scratch_list(ScratchBlock*& list) {
1063 ScratchBlock* sorted = NULL;
1064 ScratchBlock* unsorted = list;
1065 while (unsorted) {
1066 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1067 smallest->next = sorted;
1068 sorted = smallest;
1069 }
1070 list = sorted;
1071 }
1072
1073 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1074 size_t max_alloc_words) {
1075 ScratchBlock* res = NULL;
1076 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1077 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1078 sort_scratch_list(res);
1079 return res;
1080 }
1081
1082 void GenCollectedHeap::release_scratch() {
1083 _young_gen->reset_scratch();
1084 _old_gen->reset_scratch();
1085 }
1086
1087 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1088 void do_generation(Generation* gen) {
1089 gen->prepare_for_verify();
1090 }
1091 };
1092
1093 void GenCollectedHeap::prepare_for_verify() {
1094 ensure_parsability(false); // no need to retire TLABs
1095 GenPrepareForVerifyClosure blk;
1096 generation_iterate(&blk, false);
1097 }
1098
1099 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1100 bool old_to_young) {
1101 if (old_to_young) {
1102 cl->do_generation(_old_gen);
1103 cl->do_generation(_young_gen);
1104 } else {
1105 cl->do_generation(_young_gen);
1106 cl->do_generation(_old_gen);
1107 }
1108 }
1109
1110 bool GenCollectedHeap::is_maximal_no_gc() const {
1111 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1112 }
1113
1114 void GenCollectedHeap::save_marks() {
1115 _young_gen->save_marks();
1116 _old_gen->save_marks();
1117 }
1118
1119 GenCollectedHeap* GenCollectedHeap::heap() {
1120 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1121 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1122 return _gch;
1123 }
1124
1125
1126 void GenCollectedHeap::prepare_for_compaction() {
1127 guarantee(_n_gens = 2, "Wrong number of generations");
1128 // Start by compacting into same gen.
1129 CompactPoint cp(_old_gen);
1130 _old_gen->prepare_for_compaction(&cp);
1131 _young_gen->prepare_for_compaction(&cp);
1132 }
1133
1134 GCStats* GenCollectedHeap::gc_stats(int level) const {
1135 if (level == 0) {
1136 return _young_gen->gc_stats();
1137 } else {
1138 return _old_gen->gc_stats();
1139 }
1140 }
1141
1142 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1143 if (!silent) {
1144 gclog_or_tty->print("%s", _old_gen->name());
1145 gclog_or_tty->print(" ");
1146 }
1147 _old_gen->verify();
1148
1149 if (!silent) {
1150 gclog_or_tty->print("%s", _young_gen->name());
1151 gclog_or_tty->print(" ");
1152 }
1153 _young_gen->verify();
1154
1155 if (!silent) {
1156 gclog_or_tty->print("remset ");
1157 }
1158 rem_set()->verify();
1159 }
1160
1161 void GenCollectedHeap::print_on(outputStream* st) const {
1162 _young_gen->print_on(st);
1163 _old_gen->print_on(st);
1164 MetaspaceAux::print_on(st);
1165 }
1166
1167 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1168 if (workers() != NULL) {
1169 workers()->threads_do(tc);
1170 }
1171 #if INCLUDE_ALL_GCS
1172 if (UseConcMarkSweepGC) {
1173 ConcurrentMarkSweepThread::threads_do(tc);
1174 }
1175 #endif // INCLUDE_ALL_GCS
1176 }
1177
1178 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1179 #if INCLUDE_ALL_GCS
1180 if (UseConcMarkSweepGC) {
1181 workers()->print_worker_threads_on(st);
1182 ConcurrentMarkSweepThread::print_all_on(st);
1183 }
1184 #endif // INCLUDE_ALL_GCS
1185 }
1186
1187 void GenCollectedHeap::print_on_error(outputStream* st) const {
1188 this->CollectedHeap::print_on_error(st);
1189
1190 #if INCLUDE_ALL_GCS
1191 if (UseConcMarkSweepGC) {
1192 st->cr();
1193 CMSCollector::print_on_error(st);
1194 }
1195 #endif // INCLUDE_ALL_GCS
1196 }
1197
1198 void GenCollectedHeap::print_tracing_info() const {
1199 if (TraceYoungGenTime) {
1200 _young_gen->print_summary_info();
1201 }
1202 if (TraceOldGenTime) {
1203 _old_gen->print_summary_info();
1204 }
1205 }
1206
1207 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1208 if (PrintGCDetails && Verbose) {
1209 gclog_or_tty->print(" " SIZE_FORMAT
1210 "->" SIZE_FORMAT
1211 "(" SIZE_FORMAT ")",
1212 prev_used, used(), capacity());
1213 } else {
1214 gclog_or_tty->print(" " SIZE_FORMAT "K"
1215 "->" SIZE_FORMAT "K"
1216 "(" SIZE_FORMAT "K)",
1217 prev_used / K, used() / K, capacity() / K);
1218 }
1219 }
1220
1221 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1222 private:
1223 bool _full;
1224 public:
1225 void do_generation(Generation* gen) {
1226 gen->gc_prologue(_full);
1227 }
1228 GenGCPrologueClosure(bool full) : _full(full) {};
1229 };
1230
1231 void GenCollectedHeap::gc_prologue(bool full) {
1232 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1233
1234 always_do_update_barrier = false;
1235 // Fill TLAB's and such
1236 CollectedHeap::accumulate_statistics_all_tlabs();
1237 ensure_parsability(true); // retire TLABs
1238
1239 // Walk generations
1240 GenGCPrologueClosure blk(full);
1241 generation_iterate(&blk, false); // not old-to-young.
1242 };
1243
1244 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1245 private:
1246 bool _full;
1247 public:
1248 void do_generation(Generation* gen) {
1249 gen->gc_epilogue(_full);
1250 }
1251 GenGCEpilogueClosure(bool full) : _full(full) {};
1252 };
1253
1254 void GenCollectedHeap::gc_epilogue(bool full) {
1255 #ifdef COMPILER2
1256 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1257 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1258 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1259 #endif /* COMPILER2 */
1260
1261 resize_all_tlabs();
1262
1263 GenGCEpilogueClosure blk(full);
1264 generation_iterate(&blk, false); // not old-to-young.
1265
1266 if (!CleanChunkPoolAsync) {
1267 Chunk::clean_chunk_pool();
1268 }
1269
1270 MetaspaceCounters::update_performance_counters();
1271 CompressedClassSpaceCounters::update_performance_counters();
1272
1273 always_do_update_barrier = UseConcMarkSweepGC;
1274 };
1275
1276 #ifndef PRODUCT
1277 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1278 private:
1279 public:
1280 void do_generation(Generation* gen) {
1281 gen->record_spaces_top();
1282 }
1283 };
1284
1285 void GenCollectedHeap::record_gen_tops_before_GC() {
1286 if (ZapUnusedHeapArea) {
1287 GenGCSaveTopsBeforeGCClosure blk;
1288 generation_iterate(&blk, false); // not old-to-young.
1289 }
1290 }
1291 #endif // not PRODUCT
1292
1293 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1294 public:
1295 void do_generation(Generation* gen) {
1296 gen->ensure_parsability();
1297 }
1298 };
1299
1300 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1301 CollectedHeap::ensure_parsability(retire_tlabs);
1302 GenEnsureParsabilityClosure ep_cl;
1303 generation_iterate(&ep_cl, false);
1304 }
1305
1306 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1307 oop obj,
1308 size_t obj_size) {
1309 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1310 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1311 HeapWord* result = NULL;
1312
1313 result = old_gen->expand_and_allocate(obj_size, false);
1314
1315 if (result != NULL) {
1316 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1317 }
1318 return oop(result);
1319 }
1320
1321 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1322 jlong _time; // in ms
1323 jlong _now; // in ms
1324
1325 public:
1326 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1327
1328 jlong time() { return _time; }
1329
1330 void do_generation(Generation* gen) {
1331 _time = MIN2(_time, gen->time_of_last_gc(_now));
1332 }
1333 };
1334
1335 jlong GenCollectedHeap::millis_since_last_gc() {
1336 // We need a monotonically non-decreasing time in ms but
1337 // os::javaTimeMillis() does not guarantee monotonicity.
1338 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1339 GenTimeOfLastGCClosure tolgc_cl(now);
1340 // iterate over generations getting the oldest
1341 // time that a generation was collected
1342 generation_iterate(&tolgc_cl, false);
1343
1344 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1345 // provided the underlying platform provides such a time source
1346 // (and it is bug free). So we still have to guard against getting
1347 // back a time later than 'now'.
1348 jlong retVal = now - tolgc_cl.time();
1349 if (retVal < 0) {
1350 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1351 return 0;
1352 }
1353 return retVal;
1354 }