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, 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, 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 void GenCollectedHeap::save_used_regions() {
209 _old_gen->save_used_region();
210 _young_gen->save_used_region();
211 }
212
213 size_t GenCollectedHeap::max_capacity() const {
214 return _young_gen->max_capacity() + _old_gen->max_capacity();
215 }
216
217 // Update the _full_collections_completed counter
218 // at the end of a stop-world full GC.
219 unsigned int GenCollectedHeap::update_full_collections_completed() {
220 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
221 assert(_full_collections_completed <= _total_full_collections,
222 "Can't complete more collections than were started");
223 _full_collections_completed = _total_full_collections;
224 ml.notify_all();
225 return _full_collections_completed;
226 }
227
228 // Update the _full_collections_completed counter, as appropriate,
229 // at the end of a concurrent GC cycle. Note the conditional update
230 // below to allow this method to be called by a concurrent collector
231 // without synchronizing in any manner with the VM thread (which
232 // may already have initiated a STW full collection "concurrently").
233 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
234 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
235 assert((_full_collections_completed <= _total_full_collections) &&
236 (count <= _total_full_collections),
237 "Can't complete more collections than were started");
238 if (count > _full_collections_completed) {
239 _full_collections_completed = count;
240 ml.notify_all();
241 }
242 return _full_collections_completed;
243 }
244
245
246 #ifndef PRODUCT
247 // Override of memory state checking method in CollectedHeap:
248 // Some collectors (CMS for example) can't have badHeapWordVal written
249 // in the first two words of an object. (For instance , in the case of
250 // CMS these words hold state used to synchronize between certain
251 // (concurrent) GC steps and direct allocating mutators.)
252 // The skip_header_HeapWords() method below, allows us to skip
253 // over the requisite number of HeapWord's. Note that (for
254 // generational collectors) this means that those many words are
255 // skipped in each object, irrespective of the generation in which
256 // that object lives. The resultant loss of precision seems to be
257 // harmless and the pain of avoiding that imprecision appears somewhat
258 // higher than we are prepared to pay for such rudimentary debugging
259 // support.
260 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
261 size_t size) {
262 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
263 // We are asked to check a size in HeapWords,
264 // but the memory is mangled in juint words.
265 juint* start = (juint*) (addr + skip_header_HeapWords());
266 juint* end = (juint*) (addr + size);
267 for (juint* slot = start; slot < end; slot += 1) {
268 assert(*slot == badHeapWordVal,
269 "Found non badHeapWordValue in pre-allocation check");
270 }
271 }
272 }
273 #endif
274
275 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
276 bool is_tlab,
277 bool first_only) {
278 HeapWord* res = NULL;
279
280 if (_young_gen->should_allocate(size, is_tlab)) {
281 res = _young_gen->allocate(size, is_tlab);
282 if (res != NULL || first_only) {
283 return res;
284 }
285 }
286
287 if (_old_gen->should_allocate(size, is_tlab)) {
288 res = _old_gen->allocate(size, is_tlab);
289 }
290
291 return res;
292 }
293
294 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
295 bool* gc_overhead_limit_was_exceeded) {
296 return collector_policy()->mem_allocate_work(size,
297 false /* is_tlab */,
298 gc_overhead_limit_was_exceeded);
299 }
300
301 bool GenCollectedHeap::must_clear_all_soft_refs() {
302 return _gc_cause == GCCause::_last_ditch_collection;
303 }
304
305 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
306 return UseConcMarkSweepGC &&
307 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
308 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
309 }
310
311 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
312 bool is_tlab, bool run_verification, bool clear_soft_refs,
313 bool restore_marks_for_biased_locking) {
314 // Timer for individual generations. Last argument is false: no CR
315 // FIXME: We should try to start the timing earlier to cover more of the GC pause
316 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
317 // so we can assume here that the next GC id is what we want.
318 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
319 TraceCollectorStats tcs(gen->counters());
320 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
321
322 size_t prev_used = gen->used();
323 gen->stat_record()->invocations++;
324 gen->stat_record()->accumulated_time.start();
325
326 // Must be done anew before each collection because
327 // a previous collection will do mangling and will
328 // change top of some spaces.
329 record_gen_tops_before_GC();
330
331 if (PrintGC && Verbose) {
332 // I didn't want to change the logging when removing the level concept,
333 // but I guess this logging could say young/old or something instead of 0/1.
334 uint level;
335 if (gen == GenCollectedHeap::heap()->young_gen()) {
336 level = 0;
337 } else {
338 level = 1;
339 }
340 gclog_or_tty->print("level=%u invoke=%d size=" SIZE_FORMAT,
341 level,
342 gen->stat_record()->invocations,
343 size * HeapWordSize);
344 }
345
346 if (run_verification && VerifyBeforeGC) {
347 HandleMark hm; // Discard invalid handles created during verification
348 Universe::verify(" VerifyBeforeGC:");
349 }
350 COMPILER2_PRESENT(DerivedPointerTable::clear());
351
352 if (restore_marks_for_biased_locking) {
353 // We perform this mark word preservation work lazily
354 // because it's only at this point that we know whether we
355 // absolutely have to do it; we want to avoid doing it for
356 // scavenge-only collections where it's unnecessary
357 BiasedLocking::preserve_marks();
358 }
359
360 // Do collection work
361 {
362 // Note on ref discovery: For what appear to be historical reasons,
363 // GCH enables and disabled (by enqueing) refs discovery.
364 // In the future this should be moved into the generation's
365 // collect method so that ref discovery and enqueueing concerns
366 // are local to a generation. The collect method could return
367 // an appropriate indication in the case that notification on
368 // the ref lock was needed. This will make the treatment of
369 // weak refs more uniform (and indeed remove such concerns
370 // from GCH). XXX
371
372 HandleMark hm; // Discard invalid handles created during gc
373 save_marks(); // save marks for all gens
374 // We want to discover references, but not process them yet.
375 // This mode is disabled in process_discovered_references if the
376 // generation does some collection work, or in
377 // enqueue_discovered_references if the generation returns
378 // without doing any work.
379 ReferenceProcessor* rp = gen->ref_processor();
380 // If the discovery of ("weak") refs in this generation is
381 // atomic wrt other collectors in this configuration, we
382 // are guaranteed to have empty discovered ref lists.
383 if (rp->discovery_is_atomic()) {
384 rp->enable_discovery();
385 rp->setup_policy(clear_soft_refs);
386 } else {
387 // collect() below will enable discovery as appropriate
388 }
389 gen->collect(full, clear_soft_refs, size, is_tlab);
390 if (!rp->enqueuing_is_done()) {
391 rp->enqueue_discovered_references();
392 } else {
393 rp->set_enqueuing_is_done(false);
394 }
395 rp->verify_no_references_recorded();
396 }
397
398 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
399
400 gen->stat_record()->accumulated_time.stop();
401
402 update_gc_stats(gen, full);
403
404 if (run_verification && VerifyAfterGC) {
405 HandleMark hm; // Discard invalid handles created during verification
406 Universe::verify(" VerifyAfterGC:");
407 }
408
409 if (PrintGCDetails) {
410 gclog_or_tty->print(":");
411 gen->print_heap_change(prev_used);
412 }
413 }
414
415 void GenCollectedHeap::do_collection(bool full,
416 bool clear_all_soft_refs,
417 size_t size,
418 bool is_tlab,
419 Generation::Type max_generation) {
420 ResourceMark rm;
421 DEBUG_ONLY(Thread* my_thread = Thread::current();)
422
423 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
424 assert(my_thread->is_VM_thread() ||
425 my_thread->is_ConcurrentGC_thread(),
426 "incorrect thread type capability");
427 assert(Heap_lock->is_locked(),
428 "the requesting thread should have the Heap_lock");
429 guarantee(!is_gc_active(), "collection is not reentrant");
430
431 if (GC_locker::check_active_before_gc()) {
432 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
433 }
434
435 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
436 collector_policy()->should_clear_all_soft_refs();
437
438 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
439
440 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
441
442 print_heap_before_gc();
443
444 {
445 FlagSetting fl(_is_gc_active, true);
446
447 bool complete = full && (max_generation == Generation::Old);
448 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
449 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
450 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
451 // so we can assume here that the next GC id is what we want.
452 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
453
454 gc_prologue(complete);
455 increment_total_collections(complete);
456
457 size_t gch_prev_used = used();
458 bool run_verification = total_collections() >= VerifyGCStartAt;
459
460 bool prepared_for_verification = false;
461 bool collected_old = false;
462 bool old_collects_young = complete &&
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_generation == Generation::Old && _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 collected_old = true;
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 || collected_old;
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 (collected_old) {
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(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(Generation::Type type,
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 (type == Generation::Young || 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 (type == Generation::Old) {
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 // old generation scanning.
714 if (type == Generation::Young) {
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(Generation::Type gen, \
739 OopClosureType* cur, \
740 OopClosureType* older) { \
741 if (gen == Generation::Young) { \
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(bool include_young) {
754 if (include_young && !_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, Generation::Young);
785 } else {
786 #ifdef ASSERT
787 if (cause == GCCause::_scavenge_alot) {
788 // minor collection only
789 collect(cause, Generation::Young);
790 } else {
791 // Stop-the-world full collection
792 collect(cause, Generation::Old);
793 }
794 #else
795 // Stop-the-world full collection
796 collect(cause, Generation::Old);
797 #endif
798 }
799 }
800
801 void GenCollectedHeap::collect(GCCause::Cause cause, Generation::Type max_generation) {
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_generation);
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, Generation::Old);
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, Generation::Type max_generation) {
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_generation);
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, Generation::Old);
868 }
869
870 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
871 Generation::Type last_generation) {
872 Generation::Type local_last_generation;
873 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
874 gc_cause() == GCCause::_gc_locker) {
875 local_last_generation = Generation::Young;
876 } else {
877 local_last_generation = last_generation;
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_last_generation /* last_generation */);
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_last_generation == Generation::Young && 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 Generation::Old /* last_generation */);
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 return _young_gen->is_in(p) || _old_gen->is_in(p);
913 }
914
915 #ifdef ASSERT
916 // Don't implement this by using is_in_young(). This method is used
917 // in some cases to check that is_in_young() is correct.
918 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
919 assert(is_in_reserved(p) || p == NULL,
920 "Does not work if address is non-null and outside of the heap");
921 return p < _young_gen->reserved().end() && p != NULL;
922 }
923 #endif
924
925 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
926 NoHeaderExtendedOopClosure no_header_cl(cl);
927 oop_iterate(&no_header_cl);
928 }
929
930 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
931 _young_gen->oop_iterate(cl);
932 _old_gen->oop_iterate(cl);
933 }
934
935 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
936 _young_gen->object_iterate(cl);
937 _old_gen->object_iterate(cl);
938 }
939
940 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
941 _young_gen->safe_object_iterate(cl);
942 _old_gen->safe_object_iterate(cl);
943 }
944
945 Space* GenCollectedHeap::space_containing(const void* addr) const {
946 Space* res = _young_gen->space_containing(addr);
947 if (res != NULL) {
948 return res;
949 }
950 res = _old_gen->space_containing(addr);
951 assert(res != NULL, "Could not find containing space");
952 return res;
953 }
954
955 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
956 assert(is_in_reserved(addr), "block_start of address outside of heap");
957 if (_young_gen->is_in_reserved(addr)) {
958 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
959 return _young_gen->block_start(addr);
960 }
961
962 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
963 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
964 return _old_gen->block_start(addr);
965 }
966
967 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
968 assert(is_in_reserved(addr), "block_size of address outside of heap");
969 if (_young_gen->is_in_reserved(addr)) {
970 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
971 return _young_gen->block_size(addr);
972 }
973
974 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
975 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
976 return _old_gen->block_size(addr);
977 }
978
979 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
980 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
981 assert(block_start(addr) == addr, "addr must be a block start");
982 if (_young_gen->is_in_reserved(addr)) {
983 return _young_gen->block_is_obj(addr);
984 }
985
986 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
987 return _old_gen->block_is_obj(addr);
988 }
989
990 bool GenCollectedHeap::supports_tlab_allocation() const {
991 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
992 return _young_gen->supports_tlab_allocation();
993 }
994
995 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
996 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
997 if (_young_gen->supports_tlab_allocation()) {
998 return _young_gen->tlab_capacity();
999 }
1000 return 0;
1001 }
1002
1003 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1004 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1005 if (_young_gen->supports_tlab_allocation()) {
1006 return _young_gen->tlab_used();
1007 }
1008 return 0;
1009 }
1010
1011 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1012 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1013 if (_young_gen->supports_tlab_allocation()) {
1014 return _young_gen->unsafe_max_tlab_alloc();
1015 }
1016 return 0;
1017 }
1018
1019 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1020 bool gc_overhead_limit_was_exceeded;
1021 return collector_policy()->mem_allocate_work(size /* size */,
1022 true /* is_tlab */,
1023 &gc_overhead_limit_was_exceeded);
1024 }
1025
1026 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1027 // from the list headed by "*prev_ptr".
1028 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1029 bool first = true;
1030 size_t min_size = 0; // "first" makes this conceptually infinite.
1031 ScratchBlock **smallest_ptr, *smallest;
1032 ScratchBlock *cur = *prev_ptr;
1033 while (cur) {
1034 assert(*prev_ptr == cur, "just checking");
1035 if (first || cur->num_words < min_size) {
1036 smallest_ptr = prev_ptr;
1037 smallest = cur;
1038 min_size = smallest->num_words;
1039 first = false;
1040 }
1041 prev_ptr = &cur->next;
1042 cur = cur->next;
1043 }
1044 smallest = *smallest_ptr;
1045 *smallest_ptr = smallest->next;
1046 return smallest;
1047 }
1048
1049 // Sort the scratch block list headed by res into decreasing size order,
1050 // and set "res" to the result.
1051 static void sort_scratch_list(ScratchBlock*& list) {
1052 ScratchBlock* sorted = NULL;
1053 ScratchBlock* unsorted = list;
1054 while (unsorted) {
1055 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1056 smallest->next = sorted;
1057 sorted = smallest;
1058 }
1059 list = sorted;
1060 }
1061
1062 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1063 size_t max_alloc_words) {
1064 ScratchBlock* res = NULL;
1065 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1066 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1067 sort_scratch_list(res);
1068 return res;
1069 }
1070
1071 void GenCollectedHeap::release_scratch() {
1072 _young_gen->reset_scratch();
1073 _old_gen->reset_scratch();
1074 }
1075
1076 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1077 void do_generation(Generation* gen) {
1078 gen->prepare_for_verify();
1079 }
1080 };
1081
1082 void GenCollectedHeap::prepare_for_verify() {
1083 ensure_parsability(false); // no need to retire TLABs
1084 GenPrepareForVerifyClosure blk;
1085 generation_iterate(&blk, false);
1086 }
1087
1088 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1089 bool old_to_young) {
1090 if (old_to_young) {
1091 cl->do_generation(_old_gen);
1092 cl->do_generation(_young_gen);
1093 } else {
1094 cl->do_generation(_young_gen);
1095 cl->do_generation(_old_gen);
1096 }
1097 }
1098
1099 bool GenCollectedHeap::is_maximal_no_gc() const {
1100 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1101 }
1102
1103 void GenCollectedHeap::save_marks() {
1104 _young_gen->save_marks();
1105 _old_gen->save_marks();
1106 }
1107
1108 GenCollectedHeap* GenCollectedHeap::heap() {
1109 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1110 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1111 return _gch;
1112 }
1113
1114 void GenCollectedHeap::prepare_for_compaction() {
1115 // Start by compacting into same gen.
1116 CompactPoint cp(_old_gen);
1117 _old_gen->prepare_for_compaction(&cp);
1118 _young_gen->prepare_for_compaction(&cp);
1119 }
1120
1121 GCStats* GenCollectedHeap::gc_stats(Generation* gen) const {
1122 return gen->gc_stats();
1123 }
1124
1125 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1126 if (!silent) {
1127 gclog_or_tty->print("%s", _old_gen->name());
1128 gclog_or_tty->print(" ");
1129 }
1130 _old_gen->verify();
1131
1132 if (!silent) {
1133 gclog_or_tty->print("%s", _young_gen->name());
1134 gclog_or_tty->print(" ");
1135 }
1136 _young_gen->verify();
1137
1138 if (!silent) {
1139 gclog_or_tty->print("remset ");
1140 }
1141 rem_set()->verify();
1142 }
1143
1144 void GenCollectedHeap::print_on(outputStream* st) const {
1145 _young_gen->print_on(st);
1146 _old_gen->print_on(st);
1147 MetaspaceAux::print_on(st);
1148 }
1149
1150 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1151 if (workers() != NULL) {
1152 workers()->threads_do(tc);
1153 }
1154 #if INCLUDE_ALL_GCS
1155 if (UseConcMarkSweepGC) {
1156 ConcurrentMarkSweepThread::threads_do(tc);
1157 }
1158 #endif // INCLUDE_ALL_GCS
1159 }
1160
1161 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1162 #if INCLUDE_ALL_GCS
1163 if (UseConcMarkSweepGC) {
1164 workers()->print_worker_threads_on(st);
1165 ConcurrentMarkSweepThread::print_all_on(st);
1166 }
1167 #endif // INCLUDE_ALL_GCS
1168 }
1169
1170 void GenCollectedHeap::print_on_error(outputStream* st) const {
1171 this->CollectedHeap::print_on_error(st);
1172
1173 #if INCLUDE_ALL_GCS
1174 if (UseConcMarkSweepGC) {
1175 st->cr();
1176 CMSCollector::print_on_error(st);
1177 }
1178 #endif // INCLUDE_ALL_GCS
1179 }
1180
1181 void GenCollectedHeap::print_tracing_info() const {
1182 if (TraceYoungGenTime) {
1183 _young_gen->print_summary_info();
1184 }
1185 if (TraceOldGenTime) {
1186 _old_gen->print_summary_info();
1187 }
1188 }
1189
1190 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1191 if (PrintGCDetails && Verbose) {
1192 gclog_or_tty->print(" " SIZE_FORMAT
1193 "->" SIZE_FORMAT
1194 "(" SIZE_FORMAT ")",
1195 prev_used, used(), capacity());
1196 } else {
1197 gclog_or_tty->print(" " SIZE_FORMAT "K"
1198 "->" SIZE_FORMAT "K"
1199 "(" SIZE_FORMAT "K)",
1200 prev_used / K, used() / K, capacity() / K);
1201 }
1202 }
1203
1204 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1205 private:
1206 bool _full;
1207 public:
1208 void do_generation(Generation* gen) {
1209 gen->gc_prologue(_full);
1210 }
1211 GenGCPrologueClosure(bool full) : _full(full) {};
1212 };
1213
1214 void GenCollectedHeap::gc_prologue(bool full) {
1215 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1216
1217 always_do_update_barrier = false;
1218 // Fill TLAB's and such
1219 CollectedHeap::accumulate_statistics_all_tlabs();
1220 ensure_parsability(true); // retire TLABs
1221
1222 // Walk generations
1223 GenGCPrologueClosure blk(full);
1224 generation_iterate(&blk, false); // not old-to-young.
1225 };
1226
1227 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1228 private:
1229 bool _full;
1230 public:
1231 void do_generation(Generation* gen) {
1232 gen->gc_epilogue(_full);
1233 }
1234 GenGCEpilogueClosure(bool full) : _full(full) {};
1235 };
1236
1237 void GenCollectedHeap::gc_epilogue(bool full) {
1238 #ifdef COMPILER2
1239 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1240 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1241 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1242 #endif /* COMPILER2 */
1243
1244 resize_all_tlabs();
1245
1246 GenGCEpilogueClosure blk(full);
1247 generation_iterate(&blk, false); // not old-to-young.
1248
1249 if (!CleanChunkPoolAsync) {
1250 Chunk::clean_chunk_pool();
1251 }
1252
1253 MetaspaceCounters::update_performance_counters();
1254 CompressedClassSpaceCounters::update_performance_counters();
1255
1256 always_do_update_barrier = UseConcMarkSweepGC;
1257 };
1258
1259 #ifndef PRODUCT
1260 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1261 private:
1262 public:
1263 void do_generation(Generation* gen) {
1264 gen->record_spaces_top();
1265 }
1266 };
1267
1268 void GenCollectedHeap::record_gen_tops_before_GC() {
1269 if (ZapUnusedHeapArea) {
1270 GenGCSaveTopsBeforeGCClosure blk;
1271 generation_iterate(&blk, false); // not old-to-young.
1272 }
1273 }
1274 #endif // not PRODUCT
1275
1276 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1277 public:
1278 void do_generation(Generation* gen) {
1279 gen->ensure_parsability();
1280 }
1281 };
1282
1283 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1284 CollectedHeap::ensure_parsability(retire_tlabs);
1285 GenEnsureParsabilityClosure ep_cl;
1286 generation_iterate(&ep_cl, false);
1287 }
1288
1289 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1290 oop obj,
1291 size_t obj_size) {
1292 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1293 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1294 HeapWord* result = NULL;
1295
1296 result = old_gen->expand_and_allocate(obj_size, false);
1297
1298 if (result != NULL) {
1299 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1300 }
1301 return oop(result);
1302 }
1303
1304 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1305 jlong _time; // in ms
1306 jlong _now; // in ms
1307
1308 public:
1309 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1310
1311 jlong time() { return _time; }
1312
1313 void do_generation(Generation* gen) {
1314 _time = MIN2(_time, gen->time_of_last_gc(_now));
1315 }
1316 };
1317
1318 jlong GenCollectedHeap::millis_since_last_gc() {
1319 // We need a monotonically non-decreasing time in ms but
1320 // os::javaTimeMillis() does not guarantee monotonicity.
1321 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1322 GenTimeOfLastGCClosure tolgc_cl(now);
1323 // iterate over generations getting the oldest
1324 // time that a generation was collected
1325 generation_iterate(&tolgc_cl, false);
1326
1327 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1328 // provided the underlying platform provides such a time source
1329 // (and it is bug free). So we still have to guard against getting
1330 // back a time later than 'now'.
1331 jlong retVal = now - tolgc_cl.time();
1332 if (retVal < 0) {
1333 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1334 return 0;
1335 }
1336 return retVal;
1337 }