1 /*
2 * Copyright (c) 2000, 2016, 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/generation.inline.hpp"
41 #include "memory/generationSpec.hpp"
42 #include "memory/resourceArea.hpp"
43 #include "memory/sharedHeap.hpp"
44 #include "memory/space.hpp"
45 #include "oops/oop.inline.hpp"
46 #include "oops/oop.inline2.hpp"
47 #include "runtime/biasedLocking.hpp"
48 #include "runtime/fprofiler.hpp"
49 #include "runtime/handles.hpp"
50 #include "runtime/handles.inline.hpp"
51 #include "runtime/java.hpp"
52 #include "runtime/vmThread.hpp"
53 #include "services/management.hpp"
54 #include "services/memoryService.hpp"
55 #include "utilities/vmError.hpp"
56 #include "utilities/workgroup.hpp"
57 #include "utilities/macros.hpp"
58 #if INCLUDE_ALL_GCS
59 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
60 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
61 #endif // INCLUDE_ALL_GCS
62 #if INCLUDE_JFR
63 #include "jfr/jfr.hpp"
64 #endif // INCLUDE_JFR
65
66 GenCollectedHeap* GenCollectedHeap::_gch;
67 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
68
69 // The set of potentially parallel tasks in root scanning.
70 enum GCH_strong_roots_tasks {
71 GCH_PS_Universe_oops_do,
72 GCH_PS_JNIHandles_oops_do,
73 GCH_PS_ObjectSynchronizer_oops_do,
74 GCH_PS_FlatProfiler_oops_do,
75 GCH_PS_Management_oops_do,
76 GCH_PS_SystemDictionary_oops_do,
77 GCH_PS_ClassLoaderDataGraph_oops_do,
78 GCH_PS_jvmti_oops_do,
79 GCH_PS_CodeCache_oops_do,
80 GCH_PS_younger_gens,
81 // Leave this one last.
82 GCH_PS_NumElements
83 };
84
GenCollectedHeap(GenCollectorPolicy * policy)85 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
86 SharedHeap(policy),
87 _gen_policy(policy),
88 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
89 _full_collections_completed(0)
90 {
91 assert(policy != NULL, "Sanity check");
92 }
93
initialize()94 jint GenCollectedHeap::initialize() {
95 CollectedHeap::pre_initialize();
96
97 int i;
98 _n_gens = gen_policy()->number_of_generations();
99
100 // While there are no constraints in the GC code that HeapWordSize
101 // be any particular value, there are multiple other areas in the
102 // system which believe this to be true (e.g. oop->object_size in some
103 // cases incorrectly returns the size in wordSize units rather than
104 // HeapWordSize).
105 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
106
107 // The heap must be at least as aligned as generations.
108 size_t gen_alignment = Generation::GenGrain;
109
110 _gen_specs = gen_policy()->generations();
111
112 // Make sure the sizes are all aligned.
113 for (i = 0; i < _n_gens; i++) {
114 _gen_specs[i]->align(gen_alignment);
115 }
116
117 // Allocate space for the heap.
118
119 char* heap_address;
120 size_t total_reserved = 0;
121 int n_covered_regions = 0;
122 ReservedSpace heap_rs;
123
124 size_t heap_alignment = collector_policy()->heap_alignment();
125
126 heap_address = allocate(heap_alignment, &total_reserved,
127 &n_covered_regions, &heap_rs);
128
129 if (!heap_rs.is_reserved()) {
130 vm_shutdown_during_initialization(
131 "Could not reserve enough space for object heap");
132 return JNI_ENOMEM;
133 }
134
135 _reserved = MemRegion((HeapWord*)heap_rs.base(),
136 (HeapWord*)(heap_rs.base() + heap_rs.size()));
137
138 // It is important to do this in a way such that concurrent readers can't
139 // temporarily think somethings in the heap. (Seen this happen in asserts.)
140 _reserved.set_word_size(0);
141 _reserved.set_start((HeapWord*)heap_rs.base());
142 size_t actual_heap_size = heap_rs.size();
143 _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
144
145 _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
146 set_barrier_set(rem_set()->bs());
147
148 _gch = this;
149
150 for (i = 0; i < _n_gens; i++) {
151 ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), false, false);
152 _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
153 heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
154 }
155 clear_incremental_collection_failed();
156
157 #if INCLUDE_ALL_GCS
158 // If we are running CMS, create the collector responsible
159 // for collecting the CMS generations.
160 if (collector_policy()->is_concurrent_mark_sweep_policy()) {
161 bool success = create_cms_collector();
162 if (!success) return JNI_ENOMEM;
163 }
164 #endif // INCLUDE_ALL_GCS
165
166 return JNI_OK;
167 }
168
169
allocate(size_t alignment,size_t * _total_reserved,int * _n_covered_regions,ReservedSpace * heap_rs)170 char* GenCollectedHeap::allocate(size_t alignment,
171 size_t* _total_reserved,
172 int* _n_covered_regions,
173 ReservedSpace* heap_rs){
174 const char overflow_msg[] = "The size of the object heap + VM data exceeds "
175 "the maximum representable size";
176
177 // Now figure out the total size.
178 size_t total_reserved = 0;
179 int n_covered_regions = 0;
180 const size_t pageSize = UseLargePages ?
181 os::large_page_size() : os::vm_page_size();
182
183 assert(alignment % pageSize == 0, "Must be");
184
185 for (int i = 0; i < _n_gens; i++) {
186 total_reserved += _gen_specs[i]->max_size();
187 if (total_reserved < _gen_specs[i]->max_size()) {
188 vm_exit_during_initialization(overflow_msg);
189 }
190 n_covered_regions += _gen_specs[i]->n_covered_regions();
191 }
192 assert(total_reserved % alignment == 0,
193 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
194 SIZE_FORMAT, total_reserved, alignment));
195
196 // Needed until the cardtable is fixed to have the right number
197 // of covered regions.
198 n_covered_regions += 2;
199
200 *_total_reserved = total_reserved;
201 *_n_covered_regions = n_covered_regions;
202
203 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
204 return heap_rs->base();
205 }
206
207
post_initialize()208 void GenCollectedHeap::post_initialize() {
209 SharedHeap::post_initialize();
210 TwoGenerationCollectorPolicy *policy =
211 (TwoGenerationCollectorPolicy *)collector_policy();
212 guarantee(policy->is_two_generation_policy(), "Illegal policy type");
213 DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
214 assert(def_new_gen->kind() == Generation::DefNew ||
215 def_new_gen->kind() == Generation::ParNew ||
216 def_new_gen->kind() == Generation::ASParNew,
217 "Wrong generation kind");
218
219 Generation* old_gen = get_gen(1);
220 assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
221 old_gen->kind() == Generation::ASConcurrentMarkSweep ||
222 old_gen->kind() == Generation::MarkSweepCompact,
223 "Wrong generation kind");
224
225 policy->initialize_size_policy(def_new_gen->eden()->capacity(),
226 old_gen->capacity(),
227 def_new_gen->from()->capacity());
228 policy->initialize_gc_policy_counters();
229 }
230
ref_processing_init()231 void GenCollectedHeap::ref_processing_init() {
232 SharedHeap::ref_processing_init();
233 for (int i = 0; i < _n_gens; i++) {
234 _gens[i]->ref_processor_init();
235 }
236 }
237
capacity() const238 size_t GenCollectedHeap::capacity() const {
239 size_t res = 0;
240 for (int i = 0; i < _n_gens; i++) {
241 res += _gens[i]->capacity();
242 }
243 return res;
244 }
245
used() const246 size_t GenCollectedHeap::used() const {
247 size_t res = 0;
248 for (int i = 0; i < _n_gens; i++) {
249 res += _gens[i]->used();
250 }
251 return res;
252 }
253
254 // Save the "used_region" for generations level and lower.
save_used_regions(int level)255 void GenCollectedHeap::save_used_regions(int level) {
256 assert(level < _n_gens, "Illegal level parameter");
257 for (int i = level; i >= 0; i--) {
258 _gens[i]->save_used_region();
259 }
260 }
261
max_capacity() const262 size_t GenCollectedHeap::max_capacity() const {
263 size_t res = 0;
264 for (int i = 0; i < _n_gens; i++) {
265 res += _gens[i]->max_capacity();
266 }
267 return res;
268 }
269
270 // Update the _full_collections_completed counter
271 // at the end of a stop-world full GC.
update_full_collections_completed()272 unsigned int GenCollectedHeap::update_full_collections_completed() {
273 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
274 assert(_full_collections_completed <= _total_full_collections,
275 "Can't complete more collections than were started");
276 _full_collections_completed = _total_full_collections;
277 ml.notify_all();
278 return _full_collections_completed;
279 }
280
281 // Update the _full_collections_completed counter, as appropriate,
282 // at the end of a concurrent GC cycle. Note the conditional update
283 // below to allow this method to be called by a concurrent collector
284 // without synchronizing in any manner with the VM thread (which
285 // may already have initiated a STW full collection "concurrently").
update_full_collections_completed(unsigned int count)286 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
287 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
288 assert((_full_collections_completed <= _total_full_collections) &&
289 (count <= _total_full_collections),
290 "Can't complete more collections than were started");
291 if (count > _full_collections_completed) {
292 _full_collections_completed = count;
293 ml.notify_all();
294 }
295 return _full_collections_completed;
296 }
297
298
299 #ifndef PRODUCT
300 // Override of memory state checking method in CollectedHeap:
301 // Some collectors (CMS for example) can't have badHeapWordVal written
302 // in the first two words of an object. (For instance , in the case of
303 // CMS these words hold state used to synchronize between certain
304 // (concurrent) GC steps and direct allocating mutators.)
305 // The skip_header_HeapWords() method below, allows us to skip
306 // over the requisite number of HeapWord's. Note that (for
307 // generational collectors) this means that those many words are
308 // skipped in each object, irrespective of the generation in which
309 // that object lives. The resultant loss of precision seems to be
310 // harmless and the pain of avoiding that imprecision appears somewhat
311 // higher than we are prepared to pay for such rudimentary debugging
312 // support.
check_for_non_bad_heap_word_value(HeapWord * addr,size_t size)313 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
314 size_t size) {
315 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
316 // We are asked to check a size in HeapWords,
317 // but the memory is mangled in juint words.
318 juint* start = (juint*) (addr + skip_header_HeapWords());
319 juint* end = (juint*) (addr + size);
320 for (juint* slot = start; slot < end; slot += 1) {
321 assert(*slot == badHeapWordVal,
322 "Found non badHeapWordValue in pre-allocation check");
323 }
324 }
325 }
326 #endif
327
attempt_allocation(size_t size,bool is_tlab,bool first_only)328 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
329 bool is_tlab,
330 bool first_only) {
331 HeapWord* res;
332 for (int i = 0; i < _n_gens; i++) {
333 if (_gens[i]->should_allocate(size, is_tlab)) {
334 res = _gens[i]->allocate(size, is_tlab);
335 if (res != NULL) return res;
336 else if (first_only) break;
337 }
338 }
339 // Otherwise...
340 return NULL;
341 }
342
mem_allocate(size_t size,bool * gc_overhead_limit_was_exceeded)343 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
344 bool* gc_overhead_limit_was_exceeded) {
345 return collector_policy()->mem_allocate_work(size,
346 false /* is_tlab */,
347 gc_overhead_limit_was_exceeded);
348 }
349
must_clear_all_soft_refs()350 bool GenCollectedHeap::must_clear_all_soft_refs() {
351 return _gc_cause == GCCause::_last_ditch_collection;
352 }
353
should_do_concurrent_full_gc(GCCause::Cause cause)354 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
355 return UseConcMarkSweepGC &&
356 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
357 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
358 }
359
do_collection(bool full,bool clear_all_soft_refs,size_t size,bool is_tlab,int max_level)360 void GenCollectedHeap::do_collection(bool full,
361 bool clear_all_soft_refs,
362 size_t size,
363 bool is_tlab,
364 int max_level) {
365 bool prepared_for_verification = false;
366 ResourceMark rm;
367 DEBUG_ONLY(Thread* my_thread = Thread::current();)
368
369 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
370 assert(my_thread->is_VM_thread() ||
371 my_thread->is_ConcurrentGC_thread(),
372 "incorrect thread type capability");
373 assert(Heap_lock->is_locked(),
374 "the requesting thread should have the Heap_lock");
375 guarantee(!is_gc_active(), "collection is not reentrant");
376 assert(max_level < n_gens(), "sanity check");
377
378 if (GC_locker::check_active_before_gc()) {
379 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
380 }
381
382 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
383 collector_policy()->should_clear_all_soft_refs();
384
385 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
386
387 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
388
389 print_heap_before_gc();
390
391 {
392 FlagSetting fl(_is_gc_active, true);
393
394 bool complete = full && (max_level == (n_gens()-1));
395 const char* gc_cause_prefix = complete ? "Full GC" : "GC";
396 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
397 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
398 // so we can assume here that the next GC id is what we want.
399 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
400
401 gc_prologue(complete);
402 increment_total_collections(complete);
403
404 size_t gch_prev_used = used();
405
406 int starting_level = 0;
407 if (full) {
408 // Search for the oldest generation which will collect all younger
409 // generations, and start collection loop there.
410 for (int i = max_level; i >= 0; i--) {
411 if (_gens[i]->full_collects_younger_generations()) {
412 starting_level = i;
413 break;
414 }
415 }
416 }
417
418 bool must_restore_marks_for_biased_locking = false;
419
420 int max_level_collected = starting_level;
421 for (int i = starting_level; i <= max_level; i++) {
422 if (_gens[i]->should_collect(full, size, is_tlab)) {
423 if (i == n_gens() - 1) { // a major collection is to happen
424 if (!complete) {
425 // The full_collections increment was missed above.
426 increment_total_full_collections();
427 }
428 pre_full_gc_dump(NULL); // do any pre full gc dumps
429 }
430 // Timer for individual generations. Last argument is false: no CR
431 // FIXME: We should try to start the timing earlier to cover more of the GC pause
432 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
433 // so we can assume here that the next GC id is what we want.
434 GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
435 TraceCollectorStats tcs(_gens[i]->counters());
436 TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
437
438 size_t prev_used = _gens[i]->used();
439 _gens[i]->stat_record()->invocations++;
440 _gens[i]->stat_record()->accumulated_time.start();
441
442 // Must be done anew before each collection because
443 // a previous collection will do mangling and will
444 // change top of some spaces.
445 record_gen_tops_before_GC();
446
447 if (PrintGC && Verbose) {
448 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
449 i,
450 _gens[i]->stat_record()->invocations,
451 size*HeapWordSize);
452 }
453
454 if (VerifyBeforeGC && i >= VerifyGCLevel &&
455 total_collections() >= VerifyGCStartAt) {
456 HandleMark hm; // Discard invalid handles created during verification
457 if (!prepared_for_verification) {
458 prepare_for_verify();
459 prepared_for_verification = true;
460 }
461 Universe::verify(" VerifyBeforeGC:");
462 }
463 COMPILER2_PRESENT(DerivedPointerTable::clear());
464
465 if (!must_restore_marks_for_biased_locking &&
466 _gens[i]->performs_in_place_marking()) {
467 // We perform this mark word preservation work lazily
468 // because it's only at this point that we know whether we
469 // absolutely have to do it; we want to avoid doing it for
470 // scavenge-only collections where it's unnecessary
471 must_restore_marks_for_biased_locking = true;
472 BiasedLocking::preserve_marks();
473 }
474
475 // Do collection work
476 {
477 // Note on ref discovery: For what appear to be historical reasons,
478 // GCH enables and disabled (by enqueing) refs discovery.
479 // In the future this should be moved into the generation's
480 // collect method so that ref discovery and enqueueing concerns
481 // are local to a generation. The collect method could return
482 // an appropriate indication in the case that notification on
483 // the ref lock was needed. This will make the treatment of
484 // weak refs more uniform (and indeed remove such concerns
485 // from GCH). XXX
486
487 HandleMark hm; // Discard invalid handles created during gc
488 save_marks(); // save marks for all gens
489 // We want to discover references, but not process them yet.
490 // This mode is disabled in process_discovered_references if the
491 // generation does some collection work, or in
492 // enqueue_discovered_references if the generation returns
493 // without doing any work.
494 ReferenceProcessor* rp = _gens[i]->ref_processor();
495 // If the discovery of ("weak") refs in this generation is
496 // atomic wrt other collectors in this configuration, we
497 // are guaranteed to have empty discovered ref lists.
498 if (rp->discovery_is_atomic()) {
499 rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
500 rp->setup_policy(do_clear_all_soft_refs);
501 } else {
502 // collect() below will enable discovery as appropriate
503 }
504 _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
505 if (!rp->enqueuing_is_done()) {
506 rp->enqueue_discovered_references();
507 } else {
508 rp->set_enqueuing_is_done(false);
509 }
510 rp->verify_no_references_recorded();
511 }
512 max_level_collected = i;
513
514 // Determine if allocation request was met.
515 if (size > 0) {
516 if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
517 if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
518 size = 0;
519 }
520 }
521 }
522
523 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
524
525 _gens[i]->stat_record()->accumulated_time.stop();
526
527 update_gc_stats(i, full);
528
529 if (VerifyAfterGC && i >= VerifyGCLevel &&
530 total_collections() >= VerifyGCStartAt) {
531 HandleMark hm; // Discard invalid handles created during verification
532 Universe::verify(" VerifyAfterGC:");
533 }
534
535 if (PrintGCDetails) {
536 gclog_or_tty->print(":");
537 _gens[i]->print_heap_change(prev_used);
538 }
539 }
540 }
541
542 // Update "complete" boolean wrt what actually transpired --
543 // for instance, a promotion failure could have led to
544 // a whole heap collection.
545 complete = complete || (max_level_collected == n_gens() - 1);
546
547 if (complete) { // We did a "major" collection
548 // FIXME: See comment at pre_full_gc_dump call
549 post_full_gc_dump(NULL); // do any post full gc dumps
550 }
551
552 if (PrintGCDetails) {
553 print_heap_change(gch_prev_used);
554
555 // Print metaspace info for full GC with PrintGCDetails flag.
556 if (complete) {
557 MetaspaceAux::print_metaspace_change(metadata_prev_used);
558 }
559 }
560
561 for (int j = max_level_collected; j >= 0; j -= 1) {
562 // Adjust generation sizes.
563 _gens[j]->compute_new_size();
564 }
565
566 if (complete) {
567 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
568 ClassLoaderDataGraph::purge();
569 MetaspaceAux::verify_metrics();
570 // Resize the metaspace capacity after full collections
571 MetaspaceGC::compute_new_size();
572 update_full_collections_completed();
573 }
574
575 // Track memory usage and detect low memory after GC finishes
576 MemoryService::track_memory_usage();
577
578 gc_epilogue(complete);
579
580 if (must_restore_marks_for_biased_locking) {
581 BiasedLocking::restore_marks();
582 }
583 }
584
585 AdaptiveSizePolicy* sp = gen_policy()->size_policy();
586 AdaptiveSizePolicyOutput(sp, total_collections());
587
588 print_heap_after_gc();
589
590 #ifdef TRACESPINNING
591 ParallelTaskTerminator::print_termination_counts();
592 #endif
593 }
594
satisfy_failed_allocation(size_t size,bool is_tlab)595 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
596 return collector_policy()->satisfy_failed_allocation(size, is_tlab);
597 }
598
set_par_threads(uint t)599 void GenCollectedHeap::set_par_threads(uint t) {
600 SharedHeap::set_par_threads(t);
601 set_n_termination(t);
602 }
603
set_n_termination(uint t)604 void GenCollectedHeap::set_n_termination(uint t) {
605 _process_strong_tasks->set_n_threads(t);
606 }
607
608 #ifdef ASSERT
609 class AssertNonScavengableClosure: public OopClosure {
610 public:
do_oop(oop * p)611 virtual void do_oop(oop* p) {
612 assert(!Universe::heap()->is_in_partial_collection(*p),
613 "Referent should not be scavengable."); }
do_oop(narrowOop * p)614 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
615 };
616 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
617 #endif
618
process_roots(bool activate_scope,ScanningOption so,OopClosure * strong_roots,OopClosure * weak_roots,CLDClosure * strong_cld_closure,CLDClosure * weak_cld_closure,CodeBlobToOopClosure * code_roots)619 void GenCollectedHeap::process_roots(bool activate_scope,
620 ScanningOption so,
621 OopClosure* strong_roots,
622 OopClosure* weak_roots,
623 CLDClosure* strong_cld_closure,
624 CLDClosure* weak_cld_closure,
625 CodeBlobToOopClosure* code_roots) {
626 StrongRootsScope srs(this, activate_scope);
627
628 // General roots.
629 assert(_strong_roots_parity != 0, "must have called prologue code");
630 assert(code_roots != NULL, "code root closure should always be set");
631 // _n_termination for _process_strong_tasks should be set up stream
632 // in a method not running in a GC worker. Otherwise the GC worker
633 // could be trying to change the termination condition while the task
634 // is executing in another GC worker.
635
636 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
637 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
638 }
639
640 // Some CLDs contained in the thread frames should be considered strong.
641 // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
642 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
643 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
644 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
645
646 Threads::possibly_parallel_oops_do(strong_roots, roots_from_clds_p, roots_from_code_p);
647
648 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
649 Universe::oops_do(strong_roots);
650 }
651 // Global (strong) JNI handles
652 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
653 JNIHandles::oops_do(strong_roots);
654 }
655
656 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
657 ObjectSynchronizer::oops_do(strong_roots);
658 }
659 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
660 FlatProfiler::oops_do(strong_roots);
661 }
662 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
663 Management::oops_do(strong_roots);
664 }
665 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
666 JvmtiExport::oops_do(strong_roots);
667 }
668
669 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
670 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
671 }
672
673 // All threads execute the following. A specific chunk of buckets
674 // from the StringTable are the individual tasks.
675 if (weak_roots != NULL) {
676 if (CollectedHeap::use_parallel_gc_threads()) {
677 StringTable::possibly_parallel_oops_do(weak_roots);
678 } else {
679 StringTable::oops_do(weak_roots);
680 }
681 }
682
683 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
684 if (so & SO_ScavengeCodeCache) {
685 assert(code_roots != NULL, "must supply closure for code cache");
686
687 // We only visit parts of the CodeCache when scavenging.
688 CodeCache::scavenge_root_nmethods_do(code_roots);
689 }
690 if (so & SO_AllCodeCache) {
691 assert(code_roots != NULL, "must supply closure for code cache");
692
693 // CMSCollector uses this to do intermediate-strength collections.
694 // We scan the entire code cache, since CodeCache::do_unloading is not called.
695 CodeCache::blobs_do(code_roots);
696 }
697 // Verify that the code cache contents are not subject to
698 // movement by a scavenging collection.
699 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
700 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
701 }
702
703 }
704
gen_process_roots(int level,bool younger_gens_as_roots,bool activate_scope,ScanningOption so,bool only_strong_roots,OopsInGenClosure * not_older_gens,OopsInGenClosure * older_gens,CLDClosure * cld_closure)705 void GenCollectedHeap::gen_process_roots(int level,
706 bool younger_gens_as_roots,
707 bool activate_scope,
708 ScanningOption so,
709 bool only_strong_roots,
710 OopsInGenClosure* not_older_gens,
711 OopsInGenClosure* older_gens,
712 CLDClosure* cld_closure) {
713 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
714
715 bool is_moving_collection = false;
716 if (level == 0 || is_adjust_phase) {
717 // young collections are always moving
718 is_moving_collection = true;
719 }
720
721 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
722 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
723 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
724
725 process_roots(activate_scope, so,
726 not_older_gens, weak_roots,
727 cld_closure, weak_cld_closure,
728 &mark_code_closure);
729
730 if (younger_gens_as_roots) {
731 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
732 for (int i = 0; i < level; i++) {
733 not_older_gens->set_generation(_gens[i]);
734 _gens[i]->oop_iterate(not_older_gens);
735 }
736 not_older_gens->reset_generation();
737 }
738 }
739 // When collection is parallel, all threads get to cooperate to do
740 // older-gen scanning.
741 for (int i = level+1; i < _n_gens; i++) {
742 older_gens->set_generation(_gens[i]);
743 rem_set()->younger_refs_iterate(_gens[i], older_gens);
744 older_gens->reset_generation();
745 }
746
747 _process_strong_tasks->all_tasks_completed();
748 }
749
750
gen_process_weak_roots(OopClosure * root_closure)751 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
752 JNIHandles::weak_oops_do(root_closure);
753 JFR_ONLY(Jfr::weak_oops_do(root_closure));
754 for (int i = 0; i < _n_gens; i++) {
755 _gens[i]->ref_processor()->weak_oops_do(root_closure);
756 }
757 }
758
759 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
760 void GenCollectedHeap:: \
761 oop_since_save_marks_iterate(int level, \
762 OopClosureType* cur, \
763 OopClosureType* older) { \
764 _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur); \
765 for (int i = level+1; i < n_gens(); i++) { \
766 _gens[i]->oop_since_save_marks_iterate##nv_suffix(older); \
767 } \
768 }
769
ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)770 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
771
772 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
773
774 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
775 for (int i = level; i < _n_gens; i++) {
776 if (!_gens[i]->no_allocs_since_save_marks()) return false;
777 }
778 return true;
779 }
780
supports_inline_contig_alloc() const781 bool GenCollectedHeap::supports_inline_contig_alloc() const {
782 return _gens[0]->supports_inline_contig_alloc();
783 }
784
top_addr() const785 HeapWord** GenCollectedHeap::top_addr() const {
786 return _gens[0]->top_addr();
787 }
788
end_addr() const789 HeapWord** GenCollectedHeap::end_addr() const {
790 return _gens[0]->end_addr();
791 }
792
793 // public collection interfaces
794
collect(GCCause::Cause cause)795 void GenCollectedHeap::collect(GCCause::Cause cause) {
796 if (should_do_concurrent_full_gc(cause)) {
797 #if INCLUDE_ALL_GCS
798 // mostly concurrent full collection
799 collect_mostly_concurrent(cause);
800 #else // INCLUDE_ALL_GCS
801 ShouldNotReachHere();
802 #endif // INCLUDE_ALL_GCS
803 } else if ((cause == GCCause::_wb_young_gc) ||
804 (cause == GCCause::_gc_locker)) {
805 // minor collection for WhiteBox or GCLocker.
806 // _gc_locker collections upgraded by GCLockerInvokesConcurrent
807 // are handled above and never discarded.
808 collect(cause, 0);
809 } else {
810 #ifdef ASSERT
811 if (cause == GCCause::_scavenge_alot) {
812 // minor collection only
813 collect(cause, 0);
814 } else {
815 // Stop-the-world full collection
816 collect(cause, n_gens() - 1);
817 }
818 #else
819 // Stop-the-world full collection
820 collect(cause, n_gens() - 1);
821 #endif
822 }
823 }
824
collect(GCCause::Cause cause,int max_level)825 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
826 // The caller doesn't have the Heap_lock
827 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
828 MutexLocker ml(Heap_lock);
829 collect_locked(cause, max_level);
830 }
831
collect_locked(GCCause::Cause cause)832 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
833 // The caller has the Heap_lock
834 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
835 collect_locked(cause, n_gens() - 1);
836 }
837
838 // this is the private collection interface
839 // The Heap_lock is expected to be held on entry.
840
collect_locked(GCCause::Cause cause,int max_level)841 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
842 // Read the GC count while holding the Heap_lock
843 unsigned int gc_count_before = total_collections();
844 unsigned int full_gc_count_before = total_full_collections();
845
846 if (GC_locker::should_discard(cause, gc_count_before)) {
847 return;
848 }
849
850 {
851 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
852 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
853 cause, max_level);
854 VMThread::execute(&op);
855 }
856 }
857
858 #if INCLUDE_ALL_GCS
create_cms_collector()859 bool GenCollectedHeap::create_cms_collector() {
860
861 assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
862 (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)),
863 "Unexpected generation kinds");
864 // Skip two header words in the block content verification
865 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
866 CMSCollector* collector = new CMSCollector(
867 (ConcurrentMarkSweepGeneration*)_gens[1],
868 _rem_set->as_CardTableRS(),
869 (ConcurrentMarkSweepPolicy*) collector_policy());
870
871 if (collector == NULL || !collector->completed_initialization()) {
872 if (collector) {
873 delete collector; // Be nice in embedded situation
874 }
875 vm_shutdown_during_initialization("Could not create CMS collector");
876 return false;
877 }
878 return true; // success
879 }
880
collect_mostly_concurrent(GCCause::Cause cause)881 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
882 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
883
884 MutexLocker ml(Heap_lock);
885 // Read the GC counts while holding the Heap_lock
886 unsigned int full_gc_count_before = total_full_collections();
887 unsigned int gc_count_before = total_collections();
888 {
889 MutexUnlocker mu(Heap_lock);
890 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
891 VMThread::execute(&op);
892 }
893 }
894 #endif // INCLUDE_ALL_GCS
895
do_full_collection(bool clear_all_soft_refs)896 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
897 do_full_collection(clear_all_soft_refs, _n_gens - 1);
898 }
899
do_full_collection(bool clear_all_soft_refs,int max_level)900 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
901 int max_level) {
902
903 do_collection(true /* full */,
904 clear_all_soft_refs /* clear_all_soft_refs */,
905 0 /* size */,
906 false /* is_tlab */,
907 max_level /* max_level */);
908 // Hack XXX FIX ME !!!
909 // A scavenge may not have been attempted, or may have
910 // been attempted and failed, because the old gen was too full
911 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) {
912 if (PrintGCDetails) {
913 gclog_or_tty->print_cr("GC locker: Trying a full collection "
914 "because scavenge failed");
915 }
916 // This time allow the old gen to be collected as well
917 do_collection(true /* full */,
918 clear_all_soft_refs /* clear_all_soft_refs */,
919 0 /* size */,
920 false /* is_tlab */,
921 n_gens() - 1 /* max_level */);
922 }
923 }
924
is_in_young(oop p)925 bool GenCollectedHeap::is_in_young(oop p) {
926 bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
927 assert(result == _gens[0]->is_in_reserved(p),
928 err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, p2i((void*)p)));
929 return result;
930 }
931
932 // Returns "TRUE" iff "p" points into the committed areas of the heap.
is_in(const void * p) const933 bool GenCollectedHeap::is_in(const void* p) const {
934 #ifndef ASSERT
935 guarantee(VerifyBeforeGC ||
936 VerifyDuringGC ||
937 VerifyBeforeExit ||
938 VerifyDuringStartup ||
939 PrintAssembly ||
940 tty->count() != 0 || // already printing
941 VerifyAfterGC ||
942 VMError::fatal_error_in_progress(), "too expensive");
943
944 #endif
945 // This might be sped up with a cache of the last generation that
946 // answered yes.
947 for (int i = 0; i < _n_gens; i++) {
948 if (_gens[i]->is_in(p)) return true;
949 }
950 // Otherwise...
951 return false;
952 }
953
954 #ifdef ASSERT
955 // Don't implement this by using is_in_young(). This method is used
956 // in some cases to check that is_in_young() is correct.
is_in_partial_collection(const void * p)957 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
958 assert(is_in_reserved(p) || p == NULL,
959 "Does not work if address is non-null and outside of the heap");
960 return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
961 }
962 #endif
963
oop_iterate(ExtendedOopClosure * cl)964 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
965 for (int i = 0; i < _n_gens; i++) {
966 _gens[i]->oop_iterate(cl);
967 }
968 }
969
object_iterate(ObjectClosure * cl)970 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
971 for (int i = 0; i < _n_gens; i++) {
972 _gens[i]->object_iterate(cl);
973 }
974 }
975
safe_object_iterate(ObjectClosure * cl)976 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
977 for (int i = 0; i < _n_gens; i++) {
978 _gens[i]->safe_object_iterate(cl);
979 }
980 }
981
space_containing(const void * addr) const982 Space* GenCollectedHeap::space_containing(const void* addr) const {
983 for (int i = 0; i < _n_gens; i++) {
984 Space* res = _gens[i]->space_containing(addr);
985 if (res != NULL) return res;
986 }
987 // Otherwise...
988 assert(false, "Could not find containing space");
989 return NULL;
990 }
991
992
block_start(const void * addr) const993 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
994 assert(is_in_reserved(addr), "block_start of address outside of heap");
995 for (int i = 0; i < _n_gens; i++) {
996 if (_gens[i]->is_in_reserved(addr)) {
997 assert(_gens[i]->is_in(addr),
998 "addr should be in allocated part of generation");
999 return _gens[i]->block_start(addr);
1000 }
1001 }
1002 assert(false, "Some generation should contain the address");
1003 return NULL;
1004 }
1005
block_size(const HeapWord * addr) const1006 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1007 assert(is_in_reserved(addr), "block_size of address outside of heap");
1008 for (int i = 0; i < _n_gens; i++) {
1009 if (_gens[i]->is_in_reserved(addr)) {
1010 assert(_gens[i]->is_in(addr),
1011 "addr should be in allocated part of generation");
1012 return _gens[i]->block_size(addr);
1013 }
1014 }
1015 assert(false, "Some generation should contain the address");
1016 return 0;
1017 }
1018
block_is_obj(const HeapWord * addr) const1019 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1020 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1021 assert(block_start(addr) == addr, "addr must be a block start");
1022 for (int i = 0; i < _n_gens; i++) {
1023 if (_gens[i]->is_in_reserved(addr)) {
1024 return _gens[i]->block_is_obj(addr);
1025 }
1026 }
1027 assert(false, "Some generation should contain the address");
1028 return false;
1029 }
1030
supports_tlab_allocation() const1031 bool GenCollectedHeap::supports_tlab_allocation() const {
1032 for (int i = 0; i < _n_gens; i += 1) {
1033 if (_gens[i]->supports_tlab_allocation()) {
1034 return true;
1035 }
1036 }
1037 return false;
1038 }
1039
tlab_capacity(Thread * thr) const1040 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1041 size_t result = 0;
1042 for (int i = 0; i < _n_gens; i += 1) {
1043 if (_gens[i]->supports_tlab_allocation()) {
1044 result += _gens[i]->tlab_capacity();
1045 }
1046 }
1047 return result;
1048 }
1049
tlab_used(Thread * thr) const1050 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1051 size_t result = 0;
1052 for (int i = 0; i < _n_gens; i += 1) {
1053 if (_gens[i]->supports_tlab_allocation()) {
1054 result += _gens[i]->tlab_used();
1055 }
1056 }
1057 return result;
1058 }
1059
unsafe_max_tlab_alloc(Thread * thr) const1060 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1061 size_t result = 0;
1062 for (int i = 0; i < _n_gens; i += 1) {
1063 if (_gens[i]->supports_tlab_allocation()) {
1064 result += _gens[i]->unsafe_max_tlab_alloc();
1065 }
1066 }
1067 return result;
1068 }
1069
allocate_new_tlab(size_t size)1070 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1071 bool gc_overhead_limit_was_exceeded;
1072 return collector_policy()->mem_allocate_work(size /* size */,
1073 true /* is_tlab */,
1074 &gc_overhead_limit_was_exceeded);
1075 }
1076
1077 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1078 // from the list headed by "*prev_ptr".
removeSmallestScratch(ScratchBlock ** prev_ptr)1079 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1080 bool first = true;
1081 size_t min_size = 0; // "first" makes this conceptually infinite.
1082 ScratchBlock **smallest_ptr, *smallest;
1083 ScratchBlock *cur = *prev_ptr;
1084 while (cur) {
1085 assert(*prev_ptr == cur, "just checking");
1086 if (first || cur->num_words < min_size) {
1087 smallest_ptr = prev_ptr;
1088 smallest = cur;
1089 min_size = smallest->num_words;
1090 first = false;
1091 }
1092 prev_ptr = &cur->next;
1093 cur = cur->next;
1094 }
1095 smallest = *smallest_ptr;
1096 *smallest_ptr = smallest->next;
1097 return smallest;
1098 }
1099
1100 // Sort the scratch block list headed by res into decreasing size order,
1101 // and set "res" to the result.
sort_scratch_list(ScratchBlock * & list)1102 static void sort_scratch_list(ScratchBlock*& list) {
1103 ScratchBlock* sorted = NULL;
1104 ScratchBlock* unsorted = list;
1105 while (unsorted) {
1106 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1107 smallest->next = sorted;
1108 sorted = smallest;
1109 }
1110 list = sorted;
1111 }
1112
gather_scratch(Generation * requestor,size_t max_alloc_words)1113 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1114 size_t max_alloc_words) {
1115 ScratchBlock* res = NULL;
1116 for (int i = 0; i < _n_gens; i++) {
1117 _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1118 }
1119 sort_scratch_list(res);
1120 return res;
1121 }
1122
release_scratch()1123 void GenCollectedHeap::release_scratch() {
1124 for (int i = 0; i < _n_gens; i++) {
1125 _gens[i]->reset_scratch();
1126 }
1127 }
1128
1129 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
do_generation(Generation * gen)1130 void do_generation(Generation* gen) {
1131 gen->prepare_for_verify();
1132 }
1133 };
1134
prepare_for_verify()1135 void GenCollectedHeap::prepare_for_verify() {
1136 ensure_parsability(false); // no need to retire TLABs
1137 GenPrepareForVerifyClosure blk;
1138 generation_iterate(&blk, false);
1139 }
1140
1141
generation_iterate(GenClosure * cl,bool old_to_young)1142 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1143 bool old_to_young) {
1144 if (old_to_young) {
1145 for (int i = _n_gens-1; i >= 0; i--) {
1146 cl->do_generation(_gens[i]);
1147 }
1148 } else {
1149 for (int i = 0; i < _n_gens; i++) {
1150 cl->do_generation(_gens[i]);
1151 }
1152 }
1153 }
1154
space_iterate(SpaceClosure * cl)1155 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1156 for (int i = 0; i < _n_gens; i++) {
1157 _gens[i]->space_iterate(cl, true);
1158 }
1159 }
1160
is_maximal_no_gc() const1161 bool GenCollectedHeap::is_maximal_no_gc() const {
1162 for (int i = 0; i < _n_gens; i++) {
1163 if (!_gens[i]->is_maximal_no_gc()) {
1164 return false;
1165 }
1166 }
1167 return true;
1168 }
1169
save_marks()1170 void GenCollectedHeap::save_marks() {
1171 for (int i = 0; i < _n_gens; i++) {
1172 _gens[i]->save_marks();
1173 }
1174 }
1175
heap()1176 GenCollectedHeap* GenCollectedHeap::heap() {
1177 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1178 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1179 return _gch;
1180 }
1181
1182
prepare_for_compaction()1183 void GenCollectedHeap::prepare_for_compaction() {
1184 guarantee(_n_gens == 2, "Wrong number of generations");
1185 Generation* old_gen = _gens[1];
1186 // Start by compacting into same gen.
1187 CompactPoint cp(old_gen);
1188 old_gen->prepare_for_compaction(&cp);
1189 Generation* young_gen = _gens[0];
1190 young_gen->prepare_for_compaction(&cp);
1191 }
1192
gc_stats(int level) const1193 GCStats* GenCollectedHeap::gc_stats(int level) const {
1194 return _gens[level]->gc_stats();
1195 }
1196
verify(bool silent,VerifyOption option)1197 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1198 for (int i = _n_gens-1; i >= 0; i--) {
1199 Generation* g = _gens[i];
1200 if (!silent) {
1201 gclog_or_tty->print("%s", g->name());
1202 gclog_or_tty->print(" ");
1203 }
1204 g->verify();
1205 }
1206 if (!silent) {
1207 gclog_or_tty->print("remset ");
1208 }
1209 rem_set()->verify();
1210 }
1211
print_on(outputStream * st) const1212 void GenCollectedHeap::print_on(outputStream* st) const {
1213 for (int i = 0; i < _n_gens; i++) {
1214 _gens[i]->print_on(st);
1215 }
1216 MetaspaceAux::print_on(st);
1217 }
1218
gc_threads_do(ThreadClosure * tc) const1219 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1220 if (workers() != NULL) {
1221 workers()->threads_do(tc);
1222 }
1223 #if INCLUDE_ALL_GCS
1224 if (UseConcMarkSweepGC) {
1225 ConcurrentMarkSweepThread::threads_do(tc);
1226 }
1227 #endif // INCLUDE_ALL_GCS
1228 }
1229
print_gc_threads_on(outputStream * st) const1230 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1231 #if INCLUDE_ALL_GCS
1232 if (UseParNewGC) {
1233 workers()->print_worker_threads_on(st);
1234 }
1235 if (UseConcMarkSweepGC) {
1236 ConcurrentMarkSweepThread::print_all_on(st);
1237 }
1238 #endif // INCLUDE_ALL_GCS
1239 }
1240
print_on_error(outputStream * st) const1241 void GenCollectedHeap::print_on_error(outputStream* st) const {
1242 this->CollectedHeap::print_on_error(st);
1243
1244 #if INCLUDE_ALL_GCS
1245 if (UseConcMarkSweepGC) {
1246 st->cr();
1247 CMSCollector::print_on_error(st);
1248 }
1249 #endif // INCLUDE_ALL_GCS
1250 }
1251
print_tracing_info() const1252 void GenCollectedHeap::print_tracing_info() const {
1253 if (TraceGen0Time) {
1254 get_gen(0)->print_summary_info();
1255 }
1256 if (TraceGen1Time) {
1257 get_gen(1)->print_summary_info();
1258 }
1259 }
1260
print_heap_change(size_t prev_used) const1261 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1262 if (PrintGCDetails && Verbose) {
1263 gclog_or_tty->print(" " SIZE_FORMAT
1264 "->" SIZE_FORMAT
1265 "(" SIZE_FORMAT ")",
1266 prev_used, used(), capacity());
1267 } else {
1268 gclog_or_tty->print(" " SIZE_FORMAT "K"
1269 "->" SIZE_FORMAT "K"
1270 "(" SIZE_FORMAT "K)",
1271 prev_used / K, used() / K, capacity() / K);
1272 }
1273 }
1274
1275 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1276 private:
1277 bool _full;
1278 public:
do_generation(Generation * gen)1279 void do_generation(Generation* gen) {
1280 gen->gc_prologue(_full);
1281 }
GenGCPrologueClosure(bool full)1282 GenGCPrologueClosure(bool full) : _full(full) {};
1283 };
1284
gc_prologue(bool full)1285 void GenCollectedHeap::gc_prologue(bool full) {
1286 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1287
1288 always_do_update_barrier = false;
1289 // Fill TLAB's and such
1290 CollectedHeap::accumulate_statistics_all_tlabs();
1291 ensure_parsability(true); // retire TLABs
1292
1293 // Walk generations
1294 GenGCPrologueClosure blk(full);
1295 generation_iterate(&blk, false); // not old-to-young.
1296 };
1297
1298 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1299 private:
1300 bool _full;
1301 public:
do_generation(Generation * gen)1302 void do_generation(Generation* gen) {
1303 gen->gc_epilogue(_full);
1304 }
GenGCEpilogueClosure(bool full)1305 GenGCEpilogueClosure(bool full) : _full(full) {};
1306 };
1307
gc_epilogue(bool full)1308 void GenCollectedHeap::gc_epilogue(bool full) {
1309 #ifdef COMPILER2
1310 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1311 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1312 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1313 #endif /* COMPILER2 */
1314
1315 resize_all_tlabs();
1316
1317 GenGCEpilogueClosure blk(full);
1318 generation_iterate(&blk, false); // not old-to-young.
1319
1320 if (!CleanChunkPoolAsync) {
1321 Chunk::clean_chunk_pool();
1322 }
1323
1324 MetaspaceCounters::update_performance_counters();
1325 CompressedClassSpaceCounters::update_performance_counters();
1326
1327 always_do_update_barrier = UseConcMarkSweepGC;
1328 };
1329
1330 #ifndef PRODUCT
1331 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1332 private:
1333 public:
do_generation(Generation * gen)1334 void do_generation(Generation* gen) {
1335 gen->record_spaces_top();
1336 }
1337 };
1338
record_gen_tops_before_GC()1339 void GenCollectedHeap::record_gen_tops_before_GC() {
1340 if (ZapUnusedHeapArea) {
1341 GenGCSaveTopsBeforeGCClosure blk;
1342 generation_iterate(&blk, false); // not old-to-young.
1343 }
1344 }
1345 #endif // not PRODUCT
1346
1347 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1348 public:
do_generation(Generation * gen)1349 void do_generation(Generation* gen) {
1350 gen->ensure_parsability();
1351 }
1352 };
1353
ensure_parsability(bool retire_tlabs)1354 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1355 CollectedHeap::ensure_parsability(retire_tlabs);
1356 GenEnsureParsabilityClosure ep_cl;
1357 generation_iterate(&ep_cl, false);
1358 }
1359
handle_failed_promotion(Generation * old_gen,oop obj,size_t obj_size)1360 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1361 oop obj,
1362 size_t obj_size) {
1363 guarantee(old_gen->level() == 1, "We only get here with an old generation");
1364 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1365 HeapWord* result = NULL;
1366
1367 result = old_gen->expand_and_allocate(obj_size, false);
1368
1369 if (result != NULL) {
1370 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1371 }
1372 return oop(result);
1373 }
1374
1375 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1376 jlong _time; // in ms
1377 jlong _now; // in ms
1378
1379 public:
GenTimeOfLastGCClosure(jlong now)1380 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1381
time()1382 jlong time() { return _time; }
1383
do_generation(Generation * gen)1384 void do_generation(Generation* gen) {
1385 _time = MIN2(_time, gen->time_of_last_gc(_now));
1386 }
1387 };
1388
millis_since_last_gc()1389 jlong GenCollectedHeap::millis_since_last_gc() {
1390 // We need a monotonically non-deccreasing time in ms but
1391 // os::javaTimeMillis() does not guarantee monotonicity.
1392 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1393 GenTimeOfLastGCClosure tolgc_cl(now);
1394 // iterate over generations getting the oldest
1395 // time that a generation was collected
1396 generation_iterate(&tolgc_cl, false);
1397
1398 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1399 // provided the underlying platform provides such a time source
1400 // (and it is bug free). So we still have to guard against getting
1401 // back a time later than 'now'.
1402 jlong retVal = now - tolgc_cl.time();
1403 if (retVal < 0) {
1404 NOT_PRODUCT(warning("time warp: " INT64_FORMAT, (int64_t) retVal);)
1405 return 0;
1406 }
1407 return retVal;
1408 }
1409