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/strongRootsScope.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/macros.hpp"
54 #include "utilities/stack.inline.hpp"
55 #include "utilities/vmError.hpp"
56 #include "utilities/workgroup.hpp"
57 #if INCLUDE_ALL_GCS
58 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
59 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
60 #endif // INCLUDE_ALL_GCS
61
62 GenCollectedHeap* GenCollectedHeap::_gch;
63 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
64
65 // The set of potentially parallel tasks in root scanning.
66 enum GCH_strong_roots_tasks {
67 GCH_PS_Universe_oops_do,
68 GCH_PS_JNIHandles_oops_do,
69 GCH_PS_ObjectSynchronizer_oops_do,
70 GCH_PS_FlatProfiler_oops_do,
71 GCH_PS_Management_oops_do,
72 GCH_PS_SystemDictionary_oops_do,
73 GCH_PS_ClassLoaderDataGraph_oops_do,
74 GCH_PS_jvmti_oops_do,
75 GCH_PS_CodeCache_oops_do,
76 GCH_PS_younger_gens,
77 // Leave this one last.
78 GCH_PS_NumElements
79 };
80
81 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
82 CollectedHeap(),
83 _rem_set(NULL),
84 _gen_policy(policy),
85 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
86 _full_collections_completed(0)
87 {
88 assert(policy != NULL, "Sanity check");
89 if (UseConcMarkSweepGC) {
90 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
91 /* are_GC_task_threads */true,
92 /* are_ConcurrentGC_threads */false);
93 _workers->initialize_workers();
94 } else {
95 // Serial GC does not use workers.
96 _workers = NULL;
97 }
98 }
99
100 jint GenCollectedHeap::initialize() {
101 CollectedHeap::pre_initialize();
102
103 // While there are no constraints in the GC code that HeapWordSize
104 // be any particular value, there are multiple other areas in the
105 // system which believe this to be true (e.g. oop->object_size in some
106 // cases incorrectly returns the size in wordSize units rather than
107 // HeapWordSize).
108 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
109
110 // Allocate space for the heap.
111
112 char* heap_address;
113 ReservedSpace heap_rs;
114
115 size_t heap_alignment = collector_policy()->heap_alignment();
116
117 heap_address = allocate(heap_alignment, &heap_rs);
118
119 if (!heap_rs.is_reserved()) {
120 vm_shutdown_during_initialization(
121 "Could not reserve enough space for object heap");
122 return JNI_ENOMEM;
123 }
124
125 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
126
127 _rem_set = collector_policy()->create_rem_set(reserved_region());
128 set_barrier_set(rem_set()->bs());
129
130 _gch = this;
131
132 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
133 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set());
134 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
135
136 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
137 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set());
138 clear_incremental_collection_failed();
139
140 #if INCLUDE_ALL_GCS
141 // If we are running CMS, create the collector responsible
142 // for collecting the CMS generations.
143 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
144 bool success = create_cms_collector();
145 if (!success) return JNI_ENOMEM;
146 }
147 #endif // INCLUDE_ALL_GCS
148
149 return JNI_OK;
150 }
151
152 char* GenCollectedHeap::allocate(size_t alignment,
153 ReservedSpace* heap_rs){
154 // Now figure out the total size.
155 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
156 assert(alignment % pageSize == 0, "Must be");
157
158 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
159 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
160
161 // Check for overflow.
162 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
163 if (total_reserved < young_spec->max_size()) {
164 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
165 "the maximum representable size");
166 }
167 assert(total_reserved % alignment == 0,
168 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
169 SIZE_FORMAT, total_reserved, alignment));
170
171 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
172 return heap_rs->base();
173 }
174
175 void GenCollectedHeap::post_initialize() {
176 CollectedHeap::post_initialize();
177 ref_processing_init();
178 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
179 guarantee(policy->is_generation_policy(), "Illegal policy type");
180 assert((_young_gen->kind() == Generation::DefNew) ||
181 (_young_gen->kind() == Generation::ParNew),
182 "Wrong youngest generation type");
183 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
184
185 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
186 _old_gen->kind() == Generation::MarkSweepCompact,
187 "Wrong generation kind");
188
189 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
190 _old_gen->capacity(),
191 def_new_gen->from()->capacity());
192 policy->initialize_gc_policy_counters();
193 }
194
195 void GenCollectedHeap::ref_processing_init() {
196 _young_gen->ref_processor_init();
197 _old_gen->ref_processor_init();
198 }
199
200 size_t GenCollectedHeap::capacity() const {
201 return _young_gen->capacity() + _old_gen->capacity();
202 }
203
204 size_t GenCollectedHeap::used() const {
205 return _young_gen->used() + _old_gen->used();
206 }
207
208 // Save the "used_region" for generations level and lower.
209 void GenCollectedHeap::save_used_regions(int level) {
210 assert(level == 0 || level == 1, "Illegal level parameter");
211 if (level == 1) {
212 _old_gen->save_used_region();
213 }
214 _young_gen->save_used_region();
215 }
216
217 size_t GenCollectedHeap::max_capacity() const {
218 return _young_gen->max_capacity() + _old_gen->max_capacity();
219 }
220
221 // Update the _full_collections_completed counter
222 // at the end of a stop-world full GC.
223 unsigned int GenCollectedHeap::update_full_collections_completed() {
224 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
225 assert(_full_collections_completed <= _total_full_collections,
226 "Can't complete more collections than were started");
227 _full_collections_completed = _total_full_collections;
228 ml.notify_all();
229 return _full_collections_completed;
230 }
231
232 // Update the _full_collections_completed counter, as appropriate,
233 // at the end of a concurrent GC cycle. Note the conditional update
234 // below to allow this method to be called by a concurrent collector
235 // without synchronizing in any manner with the VM thread (which
236 // may already have initiated a STW full collection "concurrently").
237 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
238 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
239 assert((_full_collections_completed <= _total_full_collections) &&
240 (count <= _total_full_collections),
241 "Can't complete more collections than were started");
242 if (count > _full_collections_completed) {
243 _full_collections_completed = count;
244 ml.notify_all();
245 }
246 return _full_collections_completed;
247 }
248
249
250 #ifndef PRODUCT
251 // Override of memory state checking method in CollectedHeap:
252 // Some collectors (CMS for example) can't have badHeapWordVal written
253 // in the first two words of an object. (For instance , in the case of
254 // CMS these words hold state used to synchronize between certain
255 // (concurrent) GC steps and direct allocating mutators.)
256 // The skip_header_HeapWords() method below, allows us to skip
257 // over the requisite number of HeapWord's. Note that (for
258 // generational collectors) this means that those many words are
259 // skipped in each object, irrespective of the generation in which
260 // that object lives. The resultant loss of precision seems to be
261 // harmless and the pain of avoiding that imprecision appears somewhat
262 // higher than we are prepared to pay for such rudimentary debugging
263 // support.
264 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
265 size_t size) {
266 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
267 // We are asked to check a size in HeapWords,
268 // but the memory is mangled in juint words.
269 juint* start = (juint*) (addr + skip_header_HeapWords());
270 juint* end = (juint*) (addr + size);
271 for (juint* slot = start; slot < end; slot += 1) {
272 assert(*slot == badHeapWordVal,
273 "Found non badHeapWordValue in pre-allocation check");
274 }
275 }
276 }
277 #endif
278
279 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
280 bool is_tlab,
281 bool first_only) {
282 HeapWord* res = NULL;
283
284 if (_young_gen->should_allocate(size, is_tlab)) {
285 res = _young_gen->allocate(size, is_tlab);
286 if (res != NULL || first_only) {
287 return res;
288 }
289 }
290
291 if (_old_gen->should_allocate(size, is_tlab)) {
292 res = _old_gen->allocate(size, is_tlab);
293 }
294
295 return res;
296 }
297
298 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
299 bool* gc_overhead_limit_was_exceeded) {
300 return collector_policy()->mem_allocate_work(size,
301 false /* is_tlab */,
302 gc_overhead_limit_was_exceeded);
303 }
304
305 bool GenCollectedHeap::must_clear_all_soft_refs() {
306 return _gc_cause == GCCause::_last_ditch_collection;
307 }
308
309 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
310 return UseConcMarkSweepGC &&
311 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
312 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
313 }
314
315 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
316 bool is_tlab, bool run_verification, bool clear_soft_refs,
317 bool restore_marks_for_biased_locking) {
318 // Timer for individual generations. Last argument is false: no CR
319 // FIXME: We should try to start the timing earlier to cover more of the GC pause
320 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
321 // so we can assume here that the next GC id is what we want.
322 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
323 TraceCollectorStats tcs(gen->counters());
324 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
325
326 size_t prev_used = gen->used();
327 gen->stat_record()->invocations++;
328 gen->stat_record()->accumulated_time.start();
329
330 // Must be done anew before each collection because
331 // a previous collection will do mangling and will
332 // change top of some spaces.
333 record_gen_tops_before_GC();
334
335 if (PrintGC && Verbose) {
336 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
337 gen->level(),
338 gen->stat_record()->invocations,
339 size * HeapWordSize);
340 }
341
342 if (run_verification && VerifyBeforeGC) {
343 HandleMark hm; // Discard invalid handles created during verification
344 Universe::verify(" VerifyBeforeGC:");
345 }
346 COMPILER2_PRESENT(DerivedPointerTable::clear());
347
348 if (restore_marks_for_biased_locking) {
349 // We perform this mark word preservation work lazily
350 // because it's only at this point that we know whether we
351 // absolutely have to do it; we want to avoid doing it for
352 // scavenge-only collections where it's unnecessary
353 BiasedLocking::preserve_marks();
354 }
355
356 // Do collection work
357 {
358 // Note on ref discovery: For what appear to be historical reasons,
359 // GCH enables and disabled (by enqueing) refs discovery.
360 // In the future this should be moved into the generation's
361 // collect method so that ref discovery and enqueueing concerns
362 // are local to a generation. The collect method could return
363 // an appropriate indication in the case that notification on
364 // the ref lock was needed. This will make the treatment of
365 // weak refs more uniform (and indeed remove such concerns
366 // from GCH). XXX
367
368 HandleMark hm; // Discard invalid handles created during gc
369 save_marks(); // save marks for all gens
370 // We want to discover references, but not process them yet.
371 // This mode is disabled in process_discovered_references if the
372 // generation does some collection work, or in
373 // enqueue_discovered_references if the generation returns
374 // without doing any work.
375 ReferenceProcessor* rp = gen->ref_processor();
376 // If the discovery of ("weak") refs in this generation is
377 // atomic wrt other collectors in this configuration, we
378 // are guaranteed to have empty discovered ref lists.
379 if (rp->discovery_is_atomic()) {
380 rp->enable_discovery();
381 rp->setup_policy(clear_soft_refs);
382 } else {
383 // collect() below will enable discovery as appropriate
384 }
385 gen->collect(full, clear_soft_refs, size, is_tlab);
386 if (!rp->enqueuing_is_done()) {
387 rp->enqueue_discovered_references();
388 } else {
389 rp->set_enqueuing_is_done(false);
390 }
391 rp->verify_no_references_recorded();
392 }
393
394 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
395
396 gen->stat_record()->accumulated_time.stop();
397
398 update_gc_stats(gen->level(), full);
399
400 if (run_verification && VerifyAfterGC) {
401 HandleMark hm; // Discard invalid handles created during verification
402 Universe::verify(" VerifyAfterGC:");
403 }
404
405 if (PrintGCDetails) {
406 gclog_or_tty->print(":");
407 gen->print_heap_change(prev_used);
408 }
409 }
410
411 void GenCollectedHeap::do_collection(bool full,
412 bool clear_all_soft_refs,
413 size_t size,
414 bool is_tlab,
415 int max_level) {
416 ResourceMark rm;
417 DEBUG_ONLY(Thread* my_thread = Thread::current();)
418
419 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
420 assert(my_thread->is_VM_thread() ||
421 my_thread->is_ConcurrentGC_thread(),
422 "incorrect thread type capability");
423 assert(Heap_lock->is_locked(),
424 "the requesting thread should have the Heap_lock");
425 guarantee(!is_gc_active(), "collection is not reentrant");
426
427 if (GC_locker::check_active_before_gc()) {
428 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
429 }
430
431 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
432 collector_policy()->should_clear_all_soft_refs();
433
434 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
435
436 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
437
438 print_heap_before_gc();
439
440 {
441 FlagSetting fl(_is_gc_active, true);
442
443 bool complete = full && (max_level == 1 /* old */);
444 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
445 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
446 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
447 // so we can assume here that the next GC id is what we want.
448 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
449
450 gc_prologue(complete);
451 increment_total_collections(complete);
452
453 size_t gch_prev_used = used();
454 bool run_verification = total_collections() >= VerifyGCStartAt;
455
456 bool prepared_for_verification = false;
457 int max_level_collected = 0;
458 bool old_collects_young = (max_level == 1) &&
459 full &&
460 _old_gen->full_collects_younger_generations();
461 if (!old_collects_young &&
462 _young_gen->should_collect(full, size, is_tlab)) {
463 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
464 prepare_for_verify();
465 prepared_for_verification = true;
466 }
467
468 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
469 collect_generation(_young_gen,
470 full,
471 size,
472 is_tlab,
473 run_verification && VerifyGCLevel <= 0,
474 do_clear_all_soft_refs,
475 false);
476
477 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
478 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
479 // Allocation request was met by young GC.
480 size = 0;
481 }
482 }
483
484 bool must_restore_marks_for_biased_locking = false;
485
486 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
487 if (!complete) {
488 // The full_collections increment was missed above.
489 increment_total_full_collections();
490 }
491
492 pre_full_gc_dump(NULL); // do any pre full gc dumps
493
494 if (!prepared_for_verification && run_verification &&
495 VerifyGCLevel <= 1 && VerifyBeforeGC) {
496 prepare_for_verify();
497 }
498
499 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
500 collect_generation(_old_gen,
501 full,
502 size,
503 is_tlab,
504 run_verification && VerifyGCLevel <= 1,
505 do_clear_all_soft_refs,
506 true);
507
508 must_restore_marks_for_biased_locking = true;
509 max_level_collected = 1;
510 }
511
512 // Update "complete" boolean wrt what actually transpired --
513 // for instance, a promotion failure could have led to
514 // a whole heap collection.
515 complete = complete || (max_level_collected == 1 /* old */);
516
517 if (complete) { // We did a "major" collection
518 // FIXME: See comment at pre_full_gc_dump call
519 post_full_gc_dump(NULL); // do any post full gc dumps
520 }
521
522 if (PrintGCDetails) {
523 print_heap_change(gch_prev_used);
524
525 // Print metaspace info for full GC with PrintGCDetails flag.
526 if (complete) {
527 MetaspaceAux::print_metaspace_change(metadata_prev_used);
528 }
529 }
530
531 // Adjust generation sizes.
532 if (max_level_collected == 1 /* old */) {
533 _old_gen->compute_new_size();
534 }
535 _young_gen->compute_new_size();
536
537 if (complete) {
538 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
539 ClassLoaderDataGraph::purge();
540 MetaspaceAux::verify_metrics();
541 // Resize the metaspace capacity after full collections
542 MetaspaceGC::compute_new_size();
543 update_full_collections_completed();
544 }
545
546 // Track memory usage and detect low memory after GC finishes
547 MemoryService::track_memory_usage();
548
549 gc_epilogue(complete);
550
551 if (must_restore_marks_for_biased_locking) {
552 BiasedLocking::restore_marks();
553 }
554 }
555
556 print_heap_after_gc();
557
558 #ifdef TRACESPINNING
559 ParallelTaskTerminator::print_termination_counts();
560 #endif
561 }
562
563 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
564 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
565 }
566
567 void GenCollectedHeap::set_par_threads(uint t) {
568 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
569 CollectedHeap::set_par_threads(t);
570 set_n_termination(t);
571 }
572
573 void GenCollectedHeap::set_n_termination(uint t) {
574 _process_strong_tasks->set_n_threads(t);
575 }
576
577 #ifdef ASSERT
578 class AssertNonScavengableClosure: public OopClosure {
579 public:
580 virtual void do_oop(oop* p) {
581 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
582 "Referent should not be scavengable."); }
583 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
584 };
585 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
586 #endif
587
588 void GenCollectedHeap::process_roots(bool activate_scope,
589 ScanningOption so,
590 OopClosure* strong_roots,
591 OopClosure* weak_roots,
592 CLDClosure* strong_cld_closure,
593 CLDClosure* weak_cld_closure,
594 CodeBlobClosure* code_roots) {
595 StrongRootsScope srs(activate_scope);
596
597 // General roots.
598 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
599 assert(code_roots != NULL, "code root closure should always be set");
600 // _n_termination for _process_strong_tasks should be set up stream
601 // in a method not running in a GC worker. Otherwise the GC worker
602 // could be trying to change the termination condition while the task
603 // is executing in another GC worker.
604
605 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
606 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
607 }
608
609 // Some CLDs contained in the thread frames should be considered strong.
610 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
611 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
612 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
613 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
614
615 bool is_par = n_par_threads() > 0;
616 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
617
618 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
619 Universe::oops_do(strong_roots);
620 }
621 // Global (strong) JNI handles
622 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
623 JNIHandles::oops_do(strong_roots);
624 }
625
626 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
627 ObjectSynchronizer::oops_do(strong_roots);
628 }
629 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
630 FlatProfiler::oops_do(strong_roots);
631 }
632 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
633 Management::oops_do(strong_roots);
634 }
635 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
636 JvmtiExport::oops_do(strong_roots);
637 }
638
639 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
640 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
641 }
642
643 // All threads execute the following. A specific chunk of buckets
644 // from the StringTable are the individual tasks.
645 if (weak_roots != NULL) {
646 if (CollectedHeap::use_parallel_gc_threads()) {
647 StringTable::possibly_parallel_oops_do(weak_roots);
648 } else {
649 StringTable::oops_do(weak_roots);
650 }
651 }
652
653 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
654 if (so & SO_ScavengeCodeCache) {
655 assert(code_roots != NULL, "must supply closure for code cache");
656
657 // We only visit parts of the CodeCache when scavenging.
658 CodeCache::scavenge_root_nmethods_do(code_roots);
659 }
660 if (so & SO_AllCodeCache) {
661 assert(code_roots != NULL, "must supply closure for code cache");
662
663 // CMSCollector uses this to do intermediate-strength collections.
664 // We scan the entire code cache, since CodeCache::do_unloading is not called.
665 CodeCache::blobs_do(code_roots);
666 }
667 // Verify that the code cache contents are not subject to
668 // movement by a scavenging collection.
669 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
670 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
671 }
672
673 }
674
675 void GenCollectedHeap::gen_process_roots(int level,
676 bool younger_gens_as_roots,
677 bool activate_scope,
678 ScanningOption so,
679 bool only_strong_roots,
680 OopsInGenClosure* not_older_gens,
681 OopsInGenClosure* older_gens,
682 CLDClosure* cld_closure) {
683 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
684
685 bool is_moving_collection = false;
686 if (level == 0 || is_adjust_phase) {
687 // young collections are always moving
688 is_moving_collection = true;
689 }
690
691 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
692 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
693 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
694
695 process_roots(activate_scope, so,
696 not_older_gens, weak_roots,
697 cld_closure, weak_cld_closure,
698 &mark_code_closure);
699
700 if (younger_gens_as_roots) {
701 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
702 if (level == 1) {
703 not_older_gens->set_generation(_young_gen);
704 _young_gen->oop_iterate(not_older_gens);
705 }
706 not_older_gens->reset_generation();
707 }
708 }
709 // When collection is parallel, all threads get to cooperate to do
710 // older-gen scanning.
711 if (level == 0) {
712 older_gens->set_generation(_old_gen);
713 rem_set()->younger_refs_iterate(_old_gen, older_gens);
714 older_gens->reset_generation();
715 }
716
717 _process_strong_tasks->all_tasks_completed();
718 }
719
720
721 class AlwaysTrueClosure: public BoolObjectClosure {
722 public:
723 bool do_object_b(oop p) { return true; }
724 };
725 static AlwaysTrueClosure always_true;
726
727 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
728 JNIHandles::weak_oops_do(&always_true, root_closure);
729 _young_gen->ref_processor()->weak_oops_do(root_closure);
730 _old_gen->ref_processor()->weak_oops_do(root_closure);
731 }
732
733 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
734 void GenCollectedHeap:: \
735 oop_since_save_marks_iterate(int level, \
736 OopClosureType* cur, \
737 OopClosureType* older) { \
738 if (level == 0) { \
739 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
740 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
741 } else { \
742 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
743 } \
744 }
745
746 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
747
748 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
749
750 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
751 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) {
752 return false;
753 }
754 return _old_gen->no_allocs_since_save_marks();
755 }
756
757 bool GenCollectedHeap::supports_inline_contig_alloc() const {
758 return _young_gen->supports_inline_contig_alloc();
759 }
760
761 HeapWord** GenCollectedHeap::top_addr() const {
762 return _young_gen->top_addr();
763 }
764
765 HeapWord** GenCollectedHeap::end_addr() const {
766 return _young_gen->end_addr();
767 }
768
769 // public collection interfaces
770
771 void GenCollectedHeap::collect(GCCause::Cause cause) {
772 if (should_do_concurrent_full_gc(cause)) {
773 #if INCLUDE_ALL_GCS
774 // mostly concurrent full collection
775 collect_mostly_concurrent(cause);
776 #else // INCLUDE_ALL_GCS
777 ShouldNotReachHere();
778 #endif // INCLUDE_ALL_GCS
779 } else if (cause == GCCause::_wb_young_gc) {
780 // minor collection for WhiteBox API
781 collect(cause, 0 /* young */);
782 } else {
783 #ifdef ASSERT
784 if (cause == GCCause::_scavenge_alot) {
785 // minor collection only
786 collect(cause, 0 /* young */);
787 } else {
788 // Stop-the-world full collection
789 collect(cause, 1 /* old */);
790 }
791 #else
792 // Stop-the-world full collection
793 collect(cause, 1 /* old */);
794 #endif
795 }
796 }
797
798 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
799 // The caller doesn't have the Heap_lock
800 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
801 MutexLocker ml(Heap_lock);
802 collect_locked(cause, max_level);
803 }
804
805 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
806 // The caller has the Heap_lock
807 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
808 collect_locked(cause, 1 /* old */);
809 }
810
811 // this is the private collection interface
812 // The Heap_lock is expected to be held on entry.
813
814 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
815 // Read the GC count while holding the Heap_lock
816 unsigned int gc_count_before = total_collections();
817 unsigned int full_gc_count_before = total_full_collections();
818 {
819 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
820 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
821 cause, max_level);
822 VMThread::execute(&op);
823 }
824 }
825
826 #if INCLUDE_ALL_GCS
827 bool GenCollectedHeap::create_cms_collector() {
828
829 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
830 "Unexpected generation kinds");
831 // Skip two header words in the block content verification
832 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
833 CMSCollector* collector = new CMSCollector(
834 (ConcurrentMarkSweepGeneration*)_old_gen,
835 _rem_set->as_CardTableRS(),
836 (ConcurrentMarkSweepPolicy*) collector_policy());
837
838 if (collector == NULL || !collector->completed_initialization()) {
839 if (collector) {
840 delete collector; // Be nice in embedded situation
841 }
842 vm_shutdown_during_initialization("Could not create CMS collector");
843 return false;
844 }
845 return true; // success
846 }
847
848 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
849 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
850
851 MutexLocker ml(Heap_lock);
852 // Read the GC counts while holding the Heap_lock
853 unsigned int full_gc_count_before = total_full_collections();
854 unsigned int gc_count_before = total_collections();
855 {
856 MutexUnlocker mu(Heap_lock);
857 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
858 VMThread::execute(&op);
859 }
860 }
861 #endif // INCLUDE_ALL_GCS
862
863 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
864 do_full_collection(clear_all_soft_refs, 1 /* old */);
865 }
866
867 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
868 int max_level) {
869 int local_max_level;
870 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
871 gc_cause() == GCCause::_gc_locker) {
872 local_max_level = 0;
873 } else {
874 local_max_level = max_level;
875 }
876
877 do_collection(true /* full */,
878 clear_all_soft_refs /* clear_all_soft_refs */,
879 0 /* size */,
880 false /* is_tlab */,
881 local_max_level /* max_level */);
882 // Hack XXX FIX ME !!!
883 // A scavenge may not have been attempted, or may have
884 // been attempted and failed, because the old gen was too full
885 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
886 incremental_collection_will_fail(false /* don't consult_young */)) {
887 if (PrintGCDetails) {
888 gclog_or_tty->print_cr("GC locker: Trying a full collection "
889 "because scavenge failed");
890 }
891 // This time allow the old gen to be collected as well
892 do_collection(true /* full */,
893 clear_all_soft_refs /* clear_all_soft_refs */,
894 0 /* size */,
895 false /* is_tlab */,
896 1 /* old */ /* max_level */);
897 }
898 }
899
900 bool GenCollectedHeap::is_in_young(oop p) {
901 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
902 assert(result == _young_gen->is_in_reserved(p),
903 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
904 return result;
905 }
906
907 // Returns "TRUE" iff "p" points into the committed areas of the heap.
908 bool GenCollectedHeap::is_in(const void* p) const {
909 return _young_gen->is_in(p) || _old_gen->is_in(p);
910 }
911
912 #ifdef ASSERT
913 // Don't implement this by using is_in_young(). This method is used
914 // in some cases to check that is_in_young() is correct.
915 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
916 assert(is_in_reserved(p) || p == NULL,
917 "Does not work if address is non-null and outside of the heap");
918 return p < _young_gen->reserved().end() && p != NULL;
919 }
920 #endif
921
922 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
923 NoHeaderExtendedOopClosure no_header_cl(cl);
924 oop_iterate(&no_header_cl);
925 }
926
927 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
928 _young_gen->oop_iterate(cl);
929 _old_gen->oop_iterate(cl);
930 }
931
932 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
933 _young_gen->object_iterate(cl);
934 _old_gen->object_iterate(cl);
935 }
936
937 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
938 _young_gen->safe_object_iterate(cl);
939 _old_gen->safe_object_iterate(cl);
940 }
941
942 Space* GenCollectedHeap::space_containing(const void* addr) const {
943 Space* res = _young_gen->space_containing(addr);
944 if (res != NULL) {
945 return res;
946 }
947 res = _old_gen->space_containing(addr);
948 assert(res != NULL, "Could not find containing space");
949 return res;
950 }
951
952 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
953 assert(is_in_reserved(addr), "block_start of address outside of heap");
954 if (_young_gen->is_in_reserved(addr)) {
955 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
956 return _young_gen->block_start(addr);
957 }
958
959 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
960 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
961 return _old_gen->block_start(addr);
962 }
963
964 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
965 assert(is_in_reserved(addr), "block_size of address outside of heap");
966 if (_young_gen->is_in_reserved(addr)) {
967 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
968 return _young_gen->block_size(addr);
969 }
970
971 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
972 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
973 return _old_gen->block_size(addr);
974 }
975
976 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
977 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
978 assert(block_start(addr) == addr, "addr must be a block start");
979 if (_young_gen->is_in_reserved(addr)) {
980 return _young_gen->block_is_obj(addr);
981 }
982
983 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
984 return _old_gen->block_is_obj(addr);
985 }
986
987 bool GenCollectedHeap::supports_tlab_allocation() const {
988 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
989 return _young_gen->supports_tlab_allocation();
990 }
991
992 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
993 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
994 if (_young_gen->supports_tlab_allocation()) {
995 return _young_gen->tlab_capacity();
996 }
997 return 0;
998 }
999
1000 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1001 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1002 if (_young_gen->supports_tlab_allocation()) {
1003 return _young_gen->tlab_used();
1004 }
1005 return 0;
1006 }
1007
1008 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1009 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1010 if (_young_gen->supports_tlab_allocation()) {
1011 return _young_gen->unsafe_max_tlab_alloc();
1012 }
1013 return 0;
1014 }
1015
1016 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1017 bool gc_overhead_limit_was_exceeded;
1018 return collector_policy()->mem_allocate_work(size /* size */,
1019 true /* is_tlab */,
1020 &gc_overhead_limit_was_exceeded);
1021 }
1022
1023 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1024 // from the list headed by "*prev_ptr".
1025 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1026 bool first = true;
1027 size_t min_size = 0; // "first" makes this conceptually infinite.
1028 ScratchBlock **smallest_ptr, *smallest;
1029 ScratchBlock *cur = *prev_ptr;
1030 while (cur) {
1031 assert(*prev_ptr == cur, "just checking");
1032 if (first || cur->num_words < min_size) {
1033 smallest_ptr = prev_ptr;
1034 smallest = cur;
1035 min_size = smallest->num_words;
1036 first = false;
1037 }
1038 prev_ptr = &cur->next;
1039 cur = cur->next;
1040 }
1041 smallest = *smallest_ptr;
1042 *smallest_ptr = smallest->next;
1043 return smallest;
1044 }
1045
1046 // Sort the scratch block list headed by res into decreasing size order,
1047 // and set "res" to the result.
1048 static void sort_scratch_list(ScratchBlock*& list) {
1049 ScratchBlock* sorted = NULL;
1050 ScratchBlock* unsorted = list;
1051 while (unsorted) {
1052 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1053 smallest->next = sorted;
1054 sorted = smallest;
1055 }
1056 list = sorted;
1057 }
1058
1059 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1060 size_t max_alloc_words) {
1061 ScratchBlock* res = NULL;
1062 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1063 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1064 sort_scratch_list(res);
1065 return res;
1066 }
1067
1068 void GenCollectedHeap::release_scratch() {
1069 _young_gen->reset_scratch();
1070 _old_gen->reset_scratch();
1071 }
1072
1073 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1074 void do_generation(Generation* gen) {
1075 gen->prepare_for_verify();
1076 }
1077 };
1078
1079 void GenCollectedHeap::prepare_for_verify() {
1080 ensure_parsability(false); // no need to retire TLABs
1081 GenPrepareForVerifyClosure blk;
1082 generation_iterate(&blk, false);
1083 }
1084
1085 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1086 bool old_to_young) {
1087 if (old_to_young) {
1088 cl->do_generation(_old_gen);
1089 cl->do_generation(_young_gen);
1090 } else {
1091 cl->do_generation(_young_gen);
1092 cl->do_generation(_old_gen);
1093 }
1094 }
1095
1096 bool GenCollectedHeap::is_maximal_no_gc() const {
1097 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1098 }
1099
1100 void GenCollectedHeap::save_marks() {
1101 _young_gen->save_marks();
1102 _old_gen->save_marks();
1103 }
1104
1105 GenCollectedHeap* GenCollectedHeap::heap() {
1106 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1107 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1108 return _gch;
1109 }
1110
1111 void GenCollectedHeap::prepare_for_compaction() {
1112 // Start by compacting into same gen.
1113 CompactPoint cp(_old_gen);
1114 _old_gen->prepare_for_compaction(&cp);
1115 _young_gen->prepare_for_compaction(&cp);
1116 }
1117
1118 GCStats* GenCollectedHeap::gc_stats(int level) const {
1119 if (level == 0) {
1120 return _young_gen->gc_stats();
1121 } else {
1122 return _old_gen->gc_stats();
1123 }
1124 }
1125
1126 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1127 if (!silent) {
1128 gclog_or_tty->print("%s", _old_gen->name());
1129 gclog_or_tty->print(" ");
1130 }
1131 _old_gen->verify();
1132
1133 if (!silent) {
1134 gclog_or_tty->print("%s", _young_gen->name());
1135 gclog_or_tty->print(" ");
1136 }
1137 _young_gen->verify();
1138
1139 if (!silent) {
1140 gclog_or_tty->print("remset ");
1141 }
1142 rem_set()->verify();
1143 }
1144
1145 void GenCollectedHeap::print_on(outputStream* st) const {
1146 _young_gen->print_on(st);
1147 _old_gen->print_on(st);
1148 MetaspaceAux::print_on(st);
1149 }
1150
1151 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1152 if (workers() != NULL) {
1153 workers()->threads_do(tc);
1154 }
1155 #if INCLUDE_ALL_GCS
1156 if (UseConcMarkSweepGC) {
1157 ConcurrentMarkSweepThread::threads_do(tc);
1158 }
1159 #endif // INCLUDE_ALL_GCS
1160 }
1161
1162 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1163 #if INCLUDE_ALL_GCS
1164 if (UseConcMarkSweepGC) {
1165 workers()->print_worker_threads_on(st);
1166 ConcurrentMarkSweepThread::print_all_on(st);
1167 }
1168 #endif // INCLUDE_ALL_GCS
1169 }
1170
1171 void GenCollectedHeap::print_on_error(outputStream* st) const {
1172 this->CollectedHeap::print_on_error(st);
1173
1174 #if INCLUDE_ALL_GCS
1175 if (UseConcMarkSweepGC) {
1176 st->cr();
1177 CMSCollector::print_on_error(st);
1178 }
1179 #endif // INCLUDE_ALL_GCS
1180 }
1181
1182 void GenCollectedHeap::print_tracing_info() const {
1183 if (TraceYoungGenTime) {
1184 _young_gen->print_summary_info();
1185 }
1186 if (TraceOldGenTime) {
1187 _old_gen->print_summary_info();
1188 }
1189 }
1190
1191 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1192 if (PrintGCDetails && Verbose) {
1193 gclog_or_tty->print(" " SIZE_FORMAT
1194 "->" SIZE_FORMAT
1195 "(" SIZE_FORMAT ")",
1196 prev_used, used(), capacity());
1197 } else {
1198 gclog_or_tty->print(" " SIZE_FORMAT "K"
1199 "->" SIZE_FORMAT "K"
1200 "(" SIZE_FORMAT "K)",
1201 prev_used / K, used() / K, capacity() / K);
1202 }
1203 }
1204
1205 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1206 private:
1207 bool _full;
1208 public:
1209 void do_generation(Generation* gen) {
1210 gen->gc_prologue(_full);
1211 }
1212 GenGCPrologueClosure(bool full) : _full(full) {};
1213 };
1214
1215 void GenCollectedHeap::gc_prologue(bool full) {
1216 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1217
1218 always_do_update_barrier = false;
1219 // Fill TLAB's and such
1220 CollectedHeap::accumulate_statistics_all_tlabs();
1221 ensure_parsability(true); // retire TLABs
1222
1223 // Walk generations
1224 GenGCPrologueClosure blk(full);
1225 generation_iterate(&blk, false); // not old-to-young.
1226 };
1227
1228 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1229 private:
1230 bool _full;
1231 public:
1232 void do_generation(Generation* gen) {
1233 gen->gc_epilogue(_full);
1234 }
1235 GenGCEpilogueClosure(bool full) : _full(full) {};
1236 };
1237
1238 void GenCollectedHeap::gc_epilogue(bool full) {
1239 #ifdef COMPILER2
1240 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1241 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1242 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1243 #endif /* COMPILER2 */
1244
1245 resize_all_tlabs();
1246
1247 GenGCEpilogueClosure blk(full);
1248 generation_iterate(&blk, false); // not old-to-young.
1249
1250 if (!CleanChunkPoolAsync) {
1251 Chunk::clean_chunk_pool();
1252 }
1253
1254 MetaspaceCounters::update_performance_counters();
1255 CompressedClassSpaceCounters::update_performance_counters();
1256
1257 always_do_update_barrier = UseConcMarkSweepGC;
1258 };
1259
1260 #ifndef PRODUCT
1261 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1262 private:
1263 public:
1264 void do_generation(Generation* gen) {
1265 gen->record_spaces_top();
1266 }
1267 };
1268
1269 void GenCollectedHeap::record_gen_tops_before_GC() {
1270 if (ZapUnusedHeapArea) {
1271 GenGCSaveTopsBeforeGCClosure blk;
1272 generation_iterate(&blk, false); // not old-to-young.
1273 }
1274 }
1275 #endif // not PRODUCT
1276
1277 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1278 public:
1279 void do_generation(Generation* gen) {
1280 gen->ensure_parsability();
1281 }
1282 };
1283
1284 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1285 CollectedHeap::ensure_parsability(retire_tlabs);
1286 GenEnsureParsabilityClosure ep_cl;
1287 generation_iterate(&ep_cl, false);
1288 }
1289
1290 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1291 oop obj,
1292 size_t obj_size) {
1293 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1294 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1295 HeapWord* result = NULL;
1296
1297 result = old_gen->expand_and_allocate(obj_size, false);
1298
1299 if (result != NULL) {
1300 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1301 }
1302 return oop(result);
1303 }
1304
1305 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1306 jlong _time; // in ms
1307 jlong _now; // in ms
1308
1309 public:
1310 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1311
1312 jlong time() { return _time; }
1313
1314 void do_generation(Generation* gen) {
1315 _time = MIN2(_time, gen->time_of_last_gc(_now));
1316 }
1317 };
1318
1319 jlong GenCollectedHeap::millis_since_last_gc() {
1320 // We need a monotonically non-decreasing time in ms but
1321 // os::javaTimeMillis() does not guarantee monotonicity.
1322 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1323 GenTimeOfLastGCClosure tolgc_cl(now);
1324 // iterate over generations getting the oldest
1325 // time that a generation was collected
1326 generation_iterate(&tolgc_cl, false);
1327
1328 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1329 // provided the underlying platform provides such a time source
1330 // (and it is bug free). So we still have to guard against getting
1331 // back a time later than 'now'.
1332 jlong retVal = now - tolgc_cl.time();
1333 if (retVal < 0) {
1334 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1335 return 0;
1336 }
1337 return retVal;
1338 }