1 /*
2 * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/symbolTable.hpp"
27 #include "classfile/systemDictionary.hpp"
28 #include "classfile/vmSymbols.hpp"
29 #include "code/codeCache.hpp"
30 #include "code/icBuffer.hpp"
31 #include "gc_implementation/shared/collectorCounters.hpp"
32 #include "gc_implementation/shared/gcTrace.hpp"
33 #include "gc_implementation/shared/gcTraceTime.hpp"
34 #include "gc_implementation/shared/vmGCOperations.hpp"
35 #include "gc_interface/collectedHeap.inline.hpp"
36 #include "memory/filemap.hpp"
37 #include "memory/gcLocker.inline.hpp"
38 #include "memory/genCollectedHeap.hpp"
39 #include "memory/genOopClosures.inline.hpp"
40 #include "memory/generationSpec.hpp"
41 #include "memory/resourceArea.hpp"
42 #include "memory/sharedHeap.hpp"
43 #include "memory/space.hpp"
44 #include "oops/oop.inline.hpp"
45 #include "runtime/biasedLocking.hpp"
46 #include "runtime/fprofiler.hpp"
47 #include "runtime/handles.hpp"
48 #include "runtime/handles.inline.hpp"
49 #include "runtime/java.hpp"
50 #include "runtime/vmThread.hpp"
51 #include "services/management.hpp"
52 #include "services/memoryService.hpp"
53 #include "utilities/vmError.hpp"
54 #include "utilities/workgroup.hpp"
55 #include "utilities/macros.hpp"
56 #if INCLUDE_ALL_GCS
57 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
58 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
59 #endif // INCLUDE_ALL_GCS
60
61 GenCollectedHeap* GenCollectedHeap::_gch;
62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
63
64 // The set of potentially parallel tasks in root scanning.
65 enum GCH_strong_roots_tasks {
66 GCH_PS_Universe_oops_do,
67 GCH_PS_JNIHandles_oops_do,
68 GCH_PS_ObjectSynchronizer_oops_do,
69 GCH_PS_FlatProfiler_oops_do,
70 GCH_PS_Management_oops_do,
71 GCH_PS_SystemDictionary_oops_do,
72 GCH_PS_ClassLoaderDataGraph_oops_do,
73 GCH_PS_jvmti_oops_do,
74 GCH_PS_CodeCache_oops_do,
75 GCH_PS_younger_gens,
76 // Leave this one last.
77 GCH_PS_NumElements
78 };
79
80 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
81 SharedHeap(),
82 _rem_set(NULL),
83 _gen_policy(policy),
84 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
85 _full_collections_completed(0)
86 {
87 assert(policy != NULL, "Sanity check");
88 }
89
90 jint GenCollectedHeap::initialize() {
91 CollectedHeap::pre_initialize();
92
93 _n_gens = gen_policy()->number_of_generations();
94 assert(_n_gens == 2, "There is no support for more than two generations");
95
96 // While there are no constraints in the GC code that HeapWordSize
97 // be any particular value, there are multiple other areas in the
98 // system which believe this to be true (e.g. oop->object_size in some
99 // cases incorrectly returns the size in wordSize units rather than
100 // HeapWordSize).
101 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
102
103 // Allocate space for the heap.
104
105 char* heap_address;
106 ReservedSpace heap_rs;
107
108 size_t heap_alignment = collector_policy()->heap_alignment();
109
110 heap_address = allocate(heap_alignment, &heap_rs);
111
112 if (!heap_rs.is_reserved()) {
113 vm_shutdown_during_initialization(
114 "Could not reserve enough space for object heap");
115 return JNI_ENOMEM;
116 }
117
118 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
119
120 _rem_set = collector_policy()->create_rem_set(reserved_region());
121 _barrier_set = rem_set()->bs();
122 oopDesc::set_bs(_barrier_set);
123
124 _gch = this;
125
126 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
127 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set());
128 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
129
130 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
131 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set());
132 clear_incremental_collection_failed();
133
134 #if INCLUDE_ALL_GCS
135 // If we are running CMS, create the collector responsible
136 // for collecting the CMS generations.
137 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
138 bool success = create_cms_collector();
139 if (!success) return JNI_ENOMEM;
140 }
141 #endif // INCLUDE_ALL_GCS
142
143 return JNI_OK;
144 }
145
146 char* GenCollectedHeap::allocate(size_t alignment,
147 ReservedSpace* heap_rs){
148 // Now figure out the total size.
149 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
150 assert(alignment % pageSize == 0, "Must be");
151
152 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
153 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
154
155 // Check for overflow.
156 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
157 if (total_reserved < young_spec->max_size()) {
158 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
159 "the maximum representable size");
160 }
161 assert(total_reserved % alignment == 0,
162 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
163 SIZE_FORMAT, total_reserved, alignment));
164
165 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
166 return heap_rs->base();
167 }
168
169 void GenCollectedHeap::post_initialize() {
170 CollectedHeap::post_initialize();
171 ref_processing_init();
172 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
173 guarantee(policy->is_generation_policy(), "Illegal policy type");
174 assert((_young_gen->kind() == Generation::DefNew) ||
175 (_young_gen->kind() == Generation::ParNew),
176 "Wrong youngest generation type");
177 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
178
179 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
180 _old_gen->kind() == Generation::MarkSweepCompact,
181 "Wrong generation kind");
182
183 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
184 _old_gen->capacity(),
185 def_new_gen->from()->capacity());
186 policy->initialize_gc_policy_counters();
187 }
188
189 void GenCollectedHeap::ref_processing_init() {
190 _young_gen->ref_processor_init();
191 _old_gen->ref_processor_init();
192 }
193
194 size_t GenCollectedHeap::capacity() const {
195 return _young_gen->capacity() + _old_gen->capacity();
196 }
197
198 size_t GenCollectedHeap::used() const {
199 return _young_gen->used() + _old_gen->used();
200 }
201
202 // Save the "used_region" for generations level and lower.
203 void GenCollectedHeap::save_used_regions(int level) {
204 assert(level >= 0, "Illegal level parameter");
205 assert(level < _n_gens, "Illegal level parameter");
206 if (level == 1) {
207 _old_gen->save_used_region();
208 }
209 _young_gen->save_used_region();
210 }
211
212 size_t GenCollectedHeap::max_capacity() const {
213 return _young_gen->max_capacity() + _old_gen->max_capacity();
214 }
215
216 // Update the _full_collections_completed counter
217 // at the end of a stop-world full GC.
218 unsigned int GenCollectedHeap::update_full_collections_completed() {
219 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
220 assert(_full_collections_completed <= _total_full_collections,
221 "Can't complete more collections than were started");
222 _full_collections_completed = _total_full_collections;
223 ml.notify_all();
224 return _full_collections_completed;
225 }
226
227 // Update the _full_collections_completed counter, as appropriate,
228 // at the end of a concurrent GC cycle. Note the conditional update
229 // below to allow this method to be called by a concurrent collector
230 // without synchronizing in any manner with the VM thread (which
231 // may already have initiated a STW full collection "concurrently").
232 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
233 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
234 assert((_full_collections_completed <= _total_full_collections) &&
235 (count <= _total_full_collections),
236 "Can't complete more collections than were started");
237 if (count > _full_collections_completed) {
238 _full_collections_completed = count;
239 ml.notify_all();
240 }
241 return _full_collections_completed;
242 }
243
244
245 #ifndef PRODUCT
246 // Override of memory state checking method in CollectedHeap:
247 // Some collectors (CMS for example) can't have badHeapWordVal written
248 // in the first two words of an object. (For instance , in the case of
249 // CMS these words hold state used to synchronize between certain
250 // (concurrent) GC steps and direct allocating mutators.)
251 // The skip_header_HeapWords() method below, allows us to skip
252 // over the requisite number of HeapWord's. Note that (for
253 // generational collectors) this means that those many words are
254 // skipped in each object, irrespective of the generation in which
255 // that object lives. The resultant loss of precision seems to be
256 // harmless and the pain of avoiding that imprecision appears somewhat
257 // higher than we are prepared to pay for such rudimentary debugging
258 // support.
259 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
260 size_t size) {
261 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
262 // We are asked to check a size in HeapWords,
263 // but the memory is mangled in juint words.
264 juint* start = (juint*) (addr + skip_header_HeapWords());
265 juint* end = (juint*) (addr + size);
266 for (juint* slot = start; slot < end; slot += 1) {
267 assert(*slot == badHeapWordVal,
268 "Found non badHeapWordValue in pre-allocation check");
269 }
270 }
271 }
272 #endif
273
274 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
275 bool is_tlab,
276 bool first_only) {
277 HeapWord* res = NULL;
278
279 if (_young_gen->should_allocate(size, is_tlab)) {
280 res = _young_gen->allocate(size, is_tlab);
281 if (res != NULL || first_only) {
282 return res;
283 }
284 }
285
286 if (_old_gen->should_allocate(size, is_tlab)) {
287 res = _old_gen->allocate(size, is_tlab);
288 }
289
290 return res;
291 }
292
293 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
294 bool* gc_overhead_limit_was_exceeded) {
295 return collector_policy()->mem_allocate_work(size,
296 false /* is_tlab */,
297 gc_overhead_limit_was_exceeded);
298 }
299
300 bool GenCollectedHeap::must_clear_all_soft_refs() {
301 return _gc_cause == GCCause::_last_ditch_collection;
302 }
303
304 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
305 return UseConcMarkSweepGC &&
306 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
307 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
308 }
309
310 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
311 bool is_tlab, bool run_verification, bool clear_soft_refs,
312 bool restore_marks_for_biased_locking) {
313 // Timer for individual generations. Last argument is false: no CR
314 // FIXME: We should try to start the timing earlier to cover more of the GC pause
315 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
316 // so we can assume here that the next GC id is what we want.
317 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
318 TraceCollectorStats tcs(gen->counters());
319 TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
320
321 size_t prev_used = gen->used();
322 gen->stat_record()->invocations++;
323 gen->stat_record()->accumulated_time.start();
324
325 // Must be done anew before each collection because
326 // a previous collection will do mangling and will
327 // change top of some spaces.
328 record_gen_tops_before_GC();
329
330 if (PrintGC && Verbose) {
331 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
332 gen->level(),
333 gen->stat_record()->invocations,
334 size * HeapWordSize);
335 }
336
337 if (run_verification && VerifyBeforeGC) {
338 HandleMark hm; // Discard invalid handles created during verification
339 Universe::verify(" VerifyBeforeGC:");
340 }
341 COMPILER2_PRESENT(DerivedPointerTable::clear());
342
343 if (restore_marks_for_biased_locking) {
344 // We perform this mark word preservation work lazily
345 // because it's only at this point that we know whether we
346 // absolutely have to do it; we want to avoid doing it for
347 // scavenge-only collections where it's unnecessary
348 BiasedLocking::preserve_marks();
349 }
350
351 // Do collection work
352 {
353 // Note on ref discovery: For what appear to be historical reasons,
354 // GCH enables and disabled (by enqueing) refs discovery.
355 // In the future this should be moved into the generation's
356 // collect method so that ref discovery and enqueueing concerns
357 // are local to a generation. The collect method could return
358 // an appropriate indication in the case that notification on
359 // the ref lock was needed. This will make the treatment of
360 // weak refs more uniform (and indeed remove such concerns
361 // from GCH). XXX
362
363 HandleMark hm; // Discard invalid handles created during gc
364 save_marks(); // save marks for all gens
365 // We want to discover references, but not process them yet.
366 // This mode is disabled in process_discovered_references if the
367 // generation does some collection work, or in
368 // enqueue_discovered_references if the generation returns
369 // without doing any work.
370 ReferenceProcessor* rp = gen->ref_processor();
371 // If the discovery of ("weak") refs in this generation is
372 // atomic wrt other collectors in this configuration, we
373 // are guaranteed to have empty discovered ref lists.
374 if (rp->discovery_is_atomic()) {
375 rp->enable_discovery();
376 rp->setup_policy(clear_soft_refs);
377 } else {
378 // collect() below will enable discovery as appropriate
379 }
380 gen->collect(full, clear_soft_refs, size, is_tlab);
381 if (!rp->enqueuing_is_done()) {
382 rp->enqueue_discovered_references();
383 } else {
384 rp->set_enqueuing_is_done(false);
385 }
386 rp->verify_no_references_recorded();
387 }
388
389 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
390
391 gen->stat_record()->accumulated_time.stop();
392
393 update_gc_stats(gen->level(), full);
394
395 if (run_verification && VerifyAfterGC) {
396 HandleMark hm; // Discard invalid handles created during verification
397 Universe::verify(" VerifyAfterGC:");
398 }
399
400 if (PrintGCDetails) {
401 gclog_or_tty->print(":");
402 gen->print_heap_change(prev_used);
403 }
404 }
405
406 void GenCollectedHeap::do_collection(bool full,
407 bool clear_all_soft_refs,
408 size_t size,
409 bool is_tlab,
410 int max_level) {
411 ResourceMark rm;
412 DEBUG_ONLY(Thread* my_thread = Thread::current();)
413
414 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
415 assert(my_thread->is_VM_thread() ||
416 my_thread->is_ConcurrentGC_thread(),
417 "incorrect thread type capability");
418 assert(Heap_lock->is_locked(),
419 "the requesting thread should have the Heap_lock");
420 guarantee(!is_gc_active(), "collection is not reentrant");
421 assert(max_level < n_gens(), "sanity check");
422
423 if (GC_locker::check_active_before_gc()) {
424 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
425 }
426
427 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
428 collector_policy()->should_clear_all_soft_refs();
429
430 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
431
432 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
433
434 print_heap_before_gc();
435
436 {
437 FlagSetting fl(_is_gc_active, true);
438
439 bool complete = full && (max_level == (n_gens()-1));
440 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
441 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
442 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
443 // so we can assume here that the next GC id is what we want.
444 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
445
446 gc_prologue(complete);
447 increment_total_collections(complete);
448
449 size_t gch_prev_used = used();
450 bool run_verification = total_collections() >= VerifyGCStartAt;
451
452 bool prepared_for_verification = false;
453 int max_level_collected = 0;
454 bool old_collects_young = (max_level == 1) &&
455 full &&
456 _old_gen->full_collects_younger_generations();
457 if (!old_collects_young &&
458 _young_gen->should_collect(full, size, is_tlab)) {
459 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
460 prepare_for_verify();
461 prepared_for_verification = true;
462 }
463
464 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
465 collect_generation(_young_gen,
466 full,
467 size,
468 is_tlab,
469 run_verification && VerifyGCLevel <= 0,
470 do_clear_all_soft_refs,
471 false);
472
473 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
474 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
475 // Allocation request was met by young GC.
476 size = 0;
477 }
478 }
479
480 bool must_restore_marks_for_biased_locking = false;
481
482 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
483 if (!complete) {
484 // The full_collections increment was missed above.
485 increment_total_full_collections();
486 }
487
488 pre_full_gc_dump(NULL); // do any pre full gc dumps
489
490 if (!prepared_for_verification && run_verification &&
491 VerifyGCLevel <= 1 && VerifyBeforeGC) {
492 prepare_for_verify();
493 }
494
495 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
496 collect_generation(_old_gen,
497 full,
498 size,
499 is_tlab,
500 run_verification && VerifyGCLevel <= 1,
501 do_clear_all_soft_refs,
502 true);
503
504 must_restore_marks_for_biased_locking = true;
505 max_level_collected = 1;
506 }
507
508 // Update "complete" boolean wrt what actually transpired --
509 // for instance, a promotion failure could have led to
510 // a whole heap collection.
511 complete = complete || (max_level_collected == n_gens() - 1);
512
513 if (complete) { // We did a "major" collection
514 // FIXME: See comment at pre_full_gc_dump call
515 post_full_gc_dump(NULL); // do any post full gc dumps
516 }
517
518 if (PrintGCDetails) {
519 print_heap_change(gch_prev_used);
520
521 // Print metaspace info for full GC with PrintGCDetails flag.
522 if (complete) {
523 MetaspaceAux::print_metaspace_change(metadata_prev_used);
524 }
525 }
526
527 // Adjust generation sizes.
528 if (max_level_collected == 1) {
529 _old_gen->compute_new_size();
530 }
531 _young_gen->compute_new_size();
532
533 if (complete) {
534 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
535 ClassLoaderDataGraph::purge();
536 MetaspaceAux::verify_metrics();
537 // Resize the metaspace capacity after full collections
538 MetaspaceGC::compute_new_size();
539 update_full_collections_completed();
540 }
541
542 // Track memory usage and detect low memory after GC finishes
543 MemoryService::track_memory_usage();
544
545 gc_epilogue(complete);
546
547 if (must_restore_marks_for_biased_locking) {
548 BiasedLocking::restore_marks();
549 }
550 }
551
552 print_heap_after_gc();
553
554 #ifdef TRACESPINNING
555 ParallelTaskTerminator::print_termination_counts();
556 #endif
557 }
558
559 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
560 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
561 }
562
563 void GenCollectedHeap::set_par_threads(uint t) {
564 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
565 CollectedHeap::set_par_threads(t);
566 set_n_termination(t);
567 }
568
569 void GenCollectedHeap::set_n_termination(uint t) {
570 _process_strong_tasks->set_n_threads(t);
571 }
572
573 #ifdef ASSERT
574 class AssertNonScavengableClosure: public OopClosure {
575 public:
576 virtual void do_oop(oop* p) {
577 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
578 "Referent should not be scavengable."); }
579 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
580 };
581 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
582 #endif
583
584 void GenCollectedHeap::process_roots(bool activate_scope,
585 ScanningOption so,
586 OopClosure* strong_roots,
587 OopClosure* weak_roots,
588 CLDClosure* strong_cld_closure,
589 CLDClosure* weak_cld_closure,
590 CodeBlobClosure* code_roots) {
591 StrongRootsScope srs(this, activate_scope);
592
593 // General roots.
594 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
595 assert(code_roots != NULL, "code root closure should always be set");
596 // _n_termination for _process_strong_tasks should be set up stream
597 // in a method not running in a GC worker. Otherwise the GC worker
598 // could be trying to change the termination condition while the task
599 // is executing in another GC worker.
600
601 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
602 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
603 }
604
605 // Some CLDs contained in the thread frames should be considered strong.
606 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
607 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
608 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
609 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
610
611 bool is_par =n_par_threads() > 0;
612 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
613
614 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
615 Universe::oops_do(strong_roots);
616 }
617 // Global (strong) JNI handles
618 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
619 JNIHandles::oops_do(strong_roots);
620 }
621
622 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
623 ObjectSynchronizer::oops_do(strong_roots);
624 }
625 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
626 FlatProfiler::oops_do(strong_roots);
627 }
628 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
629 Management::oops_do(strong_roots);
630 }
631 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
632 JvmtiExport::oops_do(strong_roots);
633 }
634
635 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
636 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
637 }
638
639 // All threads execute the following. A specific chunk of buckets
640 // from the StringTable are the individual tasks.
641 if (weak_roots != NULL) {
642 if (CollectedHeap::use_parallel_gc_threads()) {
643 StringTable::possibly_parallel_oops_do(weak_roots);
644 } else {
645 StringTable::oops_do(weak_roots);
646 }
647 }
648
649 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
650 if (so & SO_ScavengeCodeCache) {
651 assert(code_roots != NULL, "must supply closure for code cache");
652
653 // We only visit parts of the CodeCache when scavenging.
654 CodeCache::scavenge_root_nmethods_do(code_roots);
655 }
656 if (so & SO_AllCodeCache) {
657 assert(code_roots != NULL, "must supply closure for code cache");
658
659 // CMSCollector uses this to do intermediate-strength collections.
660 // We scan the entire code cache, since CodeCache::do_unloading is not called.
661 CodeCache::blobs_do(code_roots);
662 }
663 // Verify that the code cache contents are not subject to
664 // movement by a scavenging collection.
665 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
666 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
667 }
668
669 }
670
671 void GenCollectedHeap::gen_process_roots(int level,
672 bool younger_gens_as_roots,
673 bool activate_scope,
674 ScanningOption so,
675 bool only_strong_roots,
676 OopsInGenClosure* not_older_gens,
677 OopsInGenClosure* older_gens,
678 CLDClosure* cld_closure) {
679 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
680
681 bool is_moving_collection = false;
682 if (level == 0 || is_adjust_phase) {
683 // young collections are always moving
684 is_moving_collection = true;
685 }
686
687 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
688 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
689 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
690
691 process_roots(activate_scope, so,
692 not_older_gens, weak_roots,
693 cld_closure, weak_cld_closure,
694 &mark_code_closure);
695
696 if (younger_gens_as_roots) {
697 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
698 if (level == 1) {
699 not_older_gens->set_generation(_young_gen);
700 _young_gen->oop_iterate(not_older_gens);
701 }
702 not_older_gens->reset_generation();
703 }
704 }
705 // When collection is parallel, all threads get to cooperate to do
706 // older-gen scanning.
707 if (level == 0) {
708 older_gens->set_generation(_old_gen);
709 rem_set()->younger_refs_iterate(_old_gen, older_gens);
710 older_gens->reset_generation();
711 }
712
713 _process_strong_tasks->all_tasks_completed();
714 }
715
716
717 class AlwaysTrueClosure: public BoolObjectClosure {
718 public:
719 bool do_object_b(oop p) { return true; }
720 };
721 static AlwaysTrueClosure always_true;
722
723 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
724 JNIHandles::weak_oops_do(&always_true, root_closure);
725 _young_gen->ref_processor()->weak_oops_do(root_closure);
726 _old_gen->ref_processor()->weak_oops_do(root_closure);
727 }
728
729 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
730 void GenCollectedHeap:: \
731 oop_since_save_marks_iterate(int level, \
732 OopClosureType* cur, \
733 OopClosureType* older) { \
734 if (level == 0) { \
735 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
736 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
737 } else { \
738 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
739 } \
740 }
741
742 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
743
744 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
745
746 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
747 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) {
748 return false;
749 }
750 return _old_gen->no_allocs_since_save_marks();
751 }
752
753 bool GenCollectedHeap::supports_inline_contig_alloc() const {
754 return _young_gen->supports_inline_contig_alloc();
755 }
756
757 HeapWord** GenCollectedHeap::top_addr() const {
758 return _young_gen->top_addr();
759 }
760
761 HeapWord** GenCollectedHeap::end_addr() const {
762 return _young_gen->end_addr();
763 }
764
765 // public collection interfaces
766
767 void GenCollectedHeap::collect(GCCause::Cause cause) {
768 if (should_do_concurrent_full_gc(cause)) {
769 #if INCLUDE_ALL_GCS
770 // mostly concurrent full collection
771 collect_mostly_concurrent(cause);
772 #else // INCLUDE_ALL_GCS
773 ShouldNotReachHere();
774 #endif // INCLUDE_ALL_GCS
775 } else if (cause == GCCause::_wb_young_gc) {
776 // minor collection for WhiteBox API
777 collect(cause, 0);
778 } else {
779 #ifdef ASSERT
780 if (cause == GCCause::_scavenge_alot) {
781 // minor collection only
782 collect(cause, 0);
783 } else {
784 // Stop-the-world full collection
785 collect(cause, n_gens() - 1);
786 }
787 #else
788 // Stop-the-world full collection
789 collect(cause, n_gens() - 1);
790 #endif
791 }
792 }
793
794 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
795 // The caller doesn't have the Heap_lock
796 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
797 MutexLocker ml(Heap_lock);
798 collect_locked(cause, max_level);
799 }
800
801 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
802 // The caller has the Heap_lock
803 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
804 collect_locked(cause, n_gens() - 1);
805 }
806
807 // this is the private collection interface
808 // The Heap_lock is expected to be held on entry.
809
810 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
811 // Read the GC count while holding the Heap_lock
812 unsigned int gc_count_before = total_collections();
813 unsigned int full_gc_count_before = total_full_collections();
814 {
815 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
816 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
817 cause, max_level);
818 VMThread::execute(&op);
819 }
820 }
821
822 #if INCLUDE_ALL_GCS
823 bool GenCollectedHeap::create_cms_collector() {
824
825 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
826 "Unexpected generation kinds");
827 // Skip two header words in the block content verification
828 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
829 CMSCollector* collector = new CMSCollector(
830 (ConcurrentMarkSweepGeneration*)_old_gen,
831 _rem_set->as_CardTableRS(),
832 (ConcurrentMarkSweepPolicy*) collector_policy());
833
834 if (collector == NULL || !collector->completed_initialization()) {
835 if (collector) {
836 delete collector; // Be nice in embedded situation
837 }
838 vm_shutdown_during_initialization("Could not create CMS collector");
839 return false;
840 }
841 return true; // success
842 }
843
844 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
845 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
846
847 MutexLocker ml(Heap_lock);
848 // Read the GC counts while holding the Heap_lock
849 unsigned int full_gc_count_before = total_full_collections();
850 unsigned int gc_count_before = total_collections();
851 {
852 MutexUnlocker mu(Heap_lock);
853 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
854 VMThread::execute(&op);
855 }
856 }
857 #endif // INCLUDE_ALL_GCS
858
859 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
860 do_full_collection(clear_all_soft_refs, _n_gens - 1);
861 }
862
863 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
864 int max_level) {
865 int local_max_level;
866 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
867 gc_cause() == GCCause::_gc_locker) {
868 local_max_level = 0;
869 } else {
870 local_max_level = max_level;
871 }
872
873 do_collection(true /* full */,
874 clear_all_soft_refs /* clear_all_soft_refs */,
875 0 /* size */,
876 false /* is_tlab */,
877 local_max_level /* max_level */);
878 // Hack XXX FIX ME !!!
879 // A scavenge may not have been attempted, or may have
880 // been attempted and failed, because the old gen was too full
881 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
882 incremental_collection_will_fail(false /* don't consult_young */)) {
883 if (PrintGCDetails) {
884 gclog_or_tty->print_cr("GC locker: Trying a full collection "
885 "because scavenge failed");
886 }
887 // This time allow the old gen to be collected as well
888 do_collection(true /* full */,
889 clear_all_soft_refs /* clear_all_soft_refs */,
890 0 /* size */,
891 false /* is_tlab */,
892 n_gens() - 1 /* max_level */);
893 }
894 }
895
896 bool GenCollectedHeap::is_in_young(oop p) {
897 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
898 assert(result == _young_gen->is_in_reserved(p),
899 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
900 return result;
901 }
902
903 // Returns "TRUE" iff "p" points into the committed areas of the heap.
904 bool GenCollectedHeap::is_in(const void* p) const {
905 #ifndef ASSERT
906 guarantee(VerifyBeforeGC ||
907 VerifyDuringGC ||
908 VerifyBeforeExit ||
909 VerifyDuringStartup ||
910 PrintAssembly ||
911 tty->count() != 0 || // already printing
912 VerifyAfterGC ||
913 VMError::fatal_error_in_progress(), "too expensive");
914
915 #endif
916 return _young_gen->is_in(p) || _old_gen->is_in(p);
917 }
918
919 #ifdef ASSERT
920 // Don't implement this by using is_in_young(). This method is used
921 // in some cases to check that is_in_young() is correct.
922 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
923 assert(is_in_reserved(p) || p == NULL,
924 "Does not work if address is non-null and outside of the heap");
925 return p < _young_gen->reserved().end() && p != NULL;
926 }
927 #endif
928
929 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
930 _young_gen->oop_iterate(cl);
931 _old_gen->oop_iterate(cl);
932 }
933
934 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
935 _young_gen->object_iterate(cl);
936 _old_gen->object_iterate(cl);
937 }
938
939 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
940 _young_gen->safe_object_iterate(cl);
941 _old_gen->safe_object_iterate(cl);
942 }
943
944 Space* GenCollectedHeap::space_containing(const void* addr) const {
945 Space* res = _young_gen->space_containing(addr);
946 if (res != NULL) {
947 return res;
948 }
949 res = _old_gen->space_containing(addr);
950 assert(res != NULL, "Could not find containing space");
951 return res;
952 }
953
954 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
955 assert(is_in_reserved(addr), "block_start of address outside of heap");
956 if (_young_gen->is_in_reserved(addr)) {
957 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
958 return _young_gen->block_start(addr);
959 }
960
961 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
962 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
963 return _old_gen->block_start(addr);
964 }
965
966 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
967 assert(is_in_reserved(addr), "block_size of address outside of heap");
968 if (_young_gen->is_in_reserved(addr)) {
969 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
970 return _young_gen->block_size(addr);
971 }
972
973 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
974 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
975 return _old_gen->block_size(addr);
976 }
977
978 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
979 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
980 assert(block_start(addr) == addr, "addr must be a block start");
981 if (_young_gen->is_in_reserved(addr)) {
982 return _young_gen->block_is_obj(addr);
983 }
984
985 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
986 return _old_gen->block_is_obj(addr);
987 }
988
989 bool GenCollectedHeap::supports_tlab_allocation() const {
990 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
991 return _young_gen->supports_tlab_allocation();
992 }
993
994 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
995 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
996 if (_young_gen->supports_tlab_allocation()) {
997 return _young_gen->tlab_capacity();
998 }
999 return 0;
1000 }
1001
1002 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1003 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1004 if (_young_gen->supports_tlab_allocation()) {
1005 return _young_gen->tlab_used();
1006 }
1007 return 0;
1008 }
1009
1010 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1011 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1012 if (_young_gen->supports_tlab_allocation()) {
1013 return _young_gen->unsafe_max_tlab_alloc();
1014 }
1015 return 0;
1016 }
1017
1018 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1019 bool gc_overhead_limit_was_exceeded;
1020 return collector_policy()->mem_allocate_work(size /* size */,
1021 true /* is_tlab */,
1022 &gc_overhead_limit_was_exceeded);
1023 }
1024
1025 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1026 // from the list headed by "*prev_ptr".
1027 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1028 bool first = true;
1029 size_t min_size = 0; // "first" makes this conceptually infinite.
1030 ScratchBlock **smallest_ptr, *smallest;
1031 ScratchBlock *cur = *prev_ptr;
1032 while (cur) {
1033 assert(*prev_ptr == cur, "just checking");
1034 if (first || cur->num_words < min_size) {
1035 smallest_ptr = prev_ptr;
1036 smallest = cur;
1037 min_size = smallest->num_words;
1038 first = false;
1039 }
1040 prev_ptr = &cur->next;
1041 cur = cur->next;
1042 }
1043 smallest = *smallest_ptr;
1044 *smallest_ptr = smallest->next;
1045 return smallest;
1046 }
1047
1048 // Sort the scratch block list headed by res into decreasing size order,
1049 // and set "res" to the result.
1050 static void sort_scratch_list(ScratchBlock*& list) {
1051 ScratchBlock* sorted = NULL;
1052 ScratchBlock* unsorted = list;
1053 while (unsorted) {
1054 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1055 smallest->next = sorted;
1056 sorted = smallest;
1057 }
1058 list = sorted;
1059 }
1060
1061 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1062 size_t max_alloc_words) {
1063 ScratchBlock* res = NULL;
1064 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1065 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1066 sort_scratch_list(res);
1067 return res;
1068 }
1069
1070 void GenCollectedHeap::release_scratch() {
1071 _young_gen->reset_scratch();
1072 _old_gen->reset_scratch();
1073 }
1074
1075 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1076 void do_generation(Generation* gen) {
1077 gen->prepare_for_verify();
1078 }
1079 };
1080
1081 void GenCollectedHeap::prepare_for_verify() {
1082 ensure_parsability(false); // no need to retire TLABs
1083 GenPrepareForVerifyClosure blk;
1084 generation_iterate(&blk, false);
1085 }
1086
1087 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1088 bool old_to_young) {
1089 if (old_to_young) {
1090 cl->do_generation(_old_gen);
1091 cl->do_generation(_young_gen);
1092 } else {
1093 cl->do_generation(_young_gen);
1094 cl->do_generation(_old_gen);
1095 }
1096 }
1097
1098 bool GenCollectedHeap::is_maximal_no_gc() const {
1099 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1100 }
1101
1102 void GenCollectedHeap::save_marks() {
1103 _young_gen->save_marks();
1104 _old_gen->save_marks();
1105 }
1106
1107 GenCollectedHeap* GenCollectedHeap::heap() {
1108 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1109 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1110 return _gch;
1111 }
1112
1113
1114 void GenCollectedHeap::prepare_for_compaction() {
1115 guarantee(_n_gens = 2, "Wrong number of generations");
1116 // Start by compacting into same gen.
1117 CompactPoint cp(_old_gen);
1118 _old_gen->prepare_for_compaction(&cp);
1119 _young_gen->prepare_for_compaction(&cp);
1120 }
1121
1122 GCStats* GenCollectedHeap::gc_stats(int level) const {
1123 if (level == 0) {
1124 return _young_gen->gc_stats();
1125 } else {
1126 return _old_gen->gc_stats();
1127 }
1128 }
1129
1130 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1131 if (!silent) {
1132 gclog_or_tty->print("%s", _old_gen->name());
1133 gclog_or_tty->print(" ");
1134 }
1135 _old_gen->verify();
1136
1137 if (!silent) {
1138 gclog_or_tty->print("%s", _young_gen->name());
1139 gclog_or_tty->print(" ");
1140 }
1141 _young_gen->verify();
1142
1143 if (!silent) {
1144 gclog_or_tty->print("remset ");
1145 }
1146 rem_set()->verify();
1147 }
1148
1149 void GenCollectedHeap::print_on(outputStream* st) const {
1150 _young_gen->print_on(st);
1151 _old_gen->print_on(st);
1152 MetaspaceAux::print_on(st);
1153 }
1154
1155 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1156 if (workers() != NULL) {
1157 workers()->threads_do(tc);
1158 }
1159 #if INCLUDE_ALL_GCS
1160 if (UseConcMarkSweepGC) {
1161 ConcurrentMarkSweepThread::threads_do(tc);
1162 }
1163 #endif // INCLUDE_ALL_GCS
1164 }
1165
1166 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1167 #if INCLUDE_ALL_GCS
1168 if (UseConcMarkSweepGC) {
1169 workers()->print_worker_threads_on(st);
1170 ConcurrentMarkSweepThread::print_all_on(st);
1171 }
1172 #endif // INCLUDE_ALL_GCS
1173 }
1174
1175 void GenCollectedHeap::print_on_error(outputStream* st) const {
1176 this->CollectedHeap::print_on_error(st);
1177
1178 #if INCLUDE_ALL_GCS
1179 if (UseConcMarkSweepGC) {
1180 st->cr();
1181 CMSCollector::print_on_error(st);
1182 }
1183 #endif // INCLUDE_ALL_GCS
1184 }
1185
1186 void GenCollectedHeap::print_tracing_info() const {
1187 if (TraceYoungGenTime) {
1188 _young_gen->print_summary_info();
1189 }
1190 if (TraceOldGenTime) {
1191 _old_gen->print_summary_info();
1192 }
1193 }
1194
1195 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1196 if (PrintGCDetails && Verbose) {
1197 gclog_or_tty->print(" " SIZE_FORMAT
1198 "->" SIZE_FORMAT
1199 "(" SIZE_FORMAT ")",
1200 prev_used, used(), capacity());
1201 } else {
1202 gclog_or_tty->print(" " SIZE_FORMAT "K"
1203 "->" SIZE_FORMAT "K"
1204 "(" SIZE_FORMAT "K)",
1205 prev_used / K, used() / K, capacity() / K);
1206 }
1207 }
1208
1209 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1210 private:
1211 bool _full;
1212 public:
1213 void do_generation(Generation* gen) {
1214 gen->gc_prologue(_full);
1215 }
1216 GenGCPrologueClosure(bool full) : _full(full) {};
1217 };
1218
1219 void GenCollectedHeap::gc_prologue(bool full) {
1220 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1221
1222 always_do_update_barrier = false;
1223 // Fill TLAB's and such
1224 CollectedHeap::accumulate_statistics_all_tlabs();
1225 ensure_parsability(true); // retire TLABs
1226
1227 // Walk generations
1228 GenGCPrologueClosure blk(full);
1229 generation_iterate(&blk, false); // not old-to-young.
1230 };
1231
1232 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1233 private:
1234 bool _full;
1235 public:
1236 void do_generation(Generation* gen) {
1237 gen->gc_epilogue(_full);
1238 }
1239 GenGCEpilogueClosure(bool full) : _full(full) {};
1240 };
1241
1242 void GenCollectedHeap::gc_epilogue(bool full) {
1243 #ifdef COMPILER2
1244 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1245 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1246 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1247 #endif /* COMPILER2 */
1248
1249 resize_all_tlabs();
1250
1251 GenGCEpilogueClosure blk(full);
1252 generation_iterate(&blk, false); // not old-to-young.
1253
1254 if (!CleanChunkPoolAsync) {
1255 Chunk::clean_chunk_pool();
1256 }
1257
1258 MetaspaceCounters::update_performance_counters();
1259 CompressedClassSpaceCounters::update_performance_counters();
1260
1261 always_do_update_barrier = UseConcMarkSweepGC;
1262 };
1263
1264 #ifndef PRODUCT
1265 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1266 private:
1267 public:
1268 void do_generation(Generation* gen) {
1269 gen->record_spaces_top();
1270 }
1271 };
1272
1273 void GenCollectedHeap::record_gen_tops_before_GC() {
1274 if (ZapUnusedHeapArea) {
1275 GenGCSaveTopsBeforeGCClosure blk;
1276 generation_iterate(&blk, false); // not old-to-young.
1277 }
1278 }
1279 #endif // not PRODUCT
1280
1281 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1282 public:
1283 void do_generation(Generation* gen) {
1284 gen->ensure_parsability();
1285 }
1286 };
1287
1288 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1289 CollectedHeap::ensure_parsability(retire_tlabs);
1290 GenEnsureParsabilityClosure ep_cl;
1291 generation_iterate(&ep_cl, false);
1292 }
1293
1294 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1295 oop obj,
1296 size_t obj_size) {
1297 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1298 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1299 HeapWord* result = NULL;
1300
1301 result = old_gen->expand_and_allocate(obj_size, false);
1302
1303 if (result != NULL) {
1304 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1305 }
1306 return oop(result);
1307 }
1308
1309 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1310 jlong _time; // in ms
1311 jlong _now; // in ms
1312
1313 public:
1314 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1315
1316 jlong time() { return _time; }
1317
1318 void do_generation(Generation* gen) {
1319 _time = MIN2(_time, gen->time_of_last_gc(_now));
1320 }
1321 };
1322
1323 jlong GenCollectedHeap::millis_since_last_gc() {
1324 // We need a monotonically non-decreasing time in ms but
1325 // os::javaTimeMillis() does not guarantee monotonicity.
1326 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1327 GenTimeOfLastGCClosure tolgc_cl(now);
1328 // iterate over generations getting the oldest
1329 // time that a generation was collected
1330 generation_iterate(&tolgc_cl, false);
1331
1332 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1333 // provided the underlying platform provides such a time source
1334 // (and it is bug free). So we still have to guard against getting
1335 // back a time later than 'now'.
1336 jlong retVal = now - tolgc_cl.time();
1337 if (retVal < 0) {
1338 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1339 return 0;
1340 }
1341 return retVal;
1342 }