1 /*
2 * Copyright (c) 2000, 2019, 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 "aot/aotLoader.hpp"
27 #include "classfile/classLoaderDataGraph.hpp"
28 #include "classfile/symbolTable.hpp"
29 #include "classfile/stringTable.hpp"
30 #include "classfile/systemDictionary.hpp"
31 #include "classfile/vmSymbols.hpp"
32 #include "code/codeCache.hpp"
33 #include "code/icBuffer.hpp"
34 #include "gc/serial/defNewGeneration.hpp"
35 #include "gc/shared/adaptiveSizePolicy.hpp"
36 #include "gc/shared/cardTableBarrierSet.hpp"
37 #include "gc/shared/cardTableRS.hpp"
38 #include "gc/shared/collectedHeap.inline.hpp"
39 #include "gc/shared/collectorCounters.hpp"
40 #include "gc/shared/gcId.hpp"
41 #include "gc/shared/gcLocker.hpp"
42 #include "gc/shared/gcPolicyCounters.hpp"
43 #include "gc/shared/gcTrace.hpp"
44 #include "gc/shared/gcTraceTime.inline.hpp"
45 #include "gc/shared/gcVMOperations.hpp"
46 #include "gc/shared/genCollectedHeap.hpp"
47 #include "gc/shared/genOopClosures.inline.hpp"
48 #include "gc/shared/generationSpec.hpp"
49 #include "gc/shared/oopStorageParState.inline.hpp"
50 #include "gc/shared/scavengableNMethods.hpp"
51 #include "gc/shared/space.hpp"
52 #include "gc/shared/strongRootsScope.hpp"
53 #include "gc/shared/weakProcessor.hpp"
54 #include "gc/shared/workgroup.hpp"
55 #include "memory/filemap.hpp"
56 #include "memory/metaspaceCounters.hpp"
57 #include "memory/resourceArea.hpp"
58 #include "oops/oop.inline.hpp"
59 #include "runtime/biasedLocking.hpp"
60 #include "runtime/flags/flagSetting.hpp"
61 #include "runtime/handles.hpp"
62 #include "runtime/handles.inline.hpp"
63 #include "runtime/java.hpp"
64 #include "runtime/vmThread.hpp"
65 #include "services/management.hpp"
66 #include "services/memoryService.hpp"
67 #include "utilities/debug.hpp"
68 #include "utilities/formatBuffer.hpp"
69 #include "utilities/macros.hpp"
70 #include "utilities/stack.inline.hpp"
71 #include "utilities/vmError.hpp"
72
73 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy,
74 Generation::Name young,
75 Generation::Name old,
76 const char* policy_counters_name) :
77 CollectedHeap(),
78 _young_gen_spec(new GenerationSpec(young,
79 policy->initial_young_size(),
80 policy->max_young_size(),
81 policy->gen_alignment())),
82 _old_gen_spec(new GenerationSpec(old,
83 policy->initial_old_size(),
84 policy->max_old_size(),
85 policy->gen_alignment())),
86 _rem_set(NULL),
87 _gen_policy(policy),
88 _soft_ref_gen_policy(),
89 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
90 _full_collections_completed(0),
91 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)) {
92 }
93
94 jint GenCollectedHeap::initialize() {
95 // While there are no constraints in the GC code that HeapWordSize
96 // be any particular value, there are multiple other areas in the
97 // system which believe this to be true (e.g. oop->object_size in some
98 // cases incorrectly returns the size in wordSize units rather than
99 // HeapWordSize).
100 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
101
102 // Allocate space for the heap.
103
104 char* heap_address;
105 ReservedSpace heap_rs;
106
107 size_t heap_alignment = collector_policy()->heap_alignment();
108
109 heap_address = allocate(heap_alignment, &heap_rs);
110
111 if (!heap_rs.is_reserved()) {
112 vm_shutdown_during_initialization(
113 "Could not reserve enough space for object heap");
114 return JNI_ENOMEM;
115 }
116
117 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
118
119 _rem_set = create_rem_set(reserved_region());
120 _rem_set->initialize();
121 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
122 bs->initialize();
123 BarrierSet::set_barrier_set(bs);
124
125 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false);
126 _young_gen = _young_gen_spec->init(young_rs, rem_set());
127 heap_rs = heap_rs.last_part(_young_gen_spec->max_size());
128
129 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false);
130 _old_gen = _old_gen_spec->init(old_rs, rem_set());
131 clear_incremental_collection_failed();
132
133 return JNI_OK;
134 }
135
136 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
137 return new CardTableRS(reserved_region, false /* scan_concurrently */);
138 }
139
140 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
141 size_t init_promo_size,
142 size_t init_survivor_size) {
143 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
144 _size_policy = new AdaptiveSizePolicy(init_eden_size,
145 init_promo_size,
146 init_survivor_size,
147 max_gc_pause_sec,
148 GCTimeRatio);
149 }
150
151 char* GenCollectedHeap::allocate(size_t alignment,
152 ReservedSpace* heap_rs){
153 // Now figure out the total size.
154 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
155 assert(alignment % pageSize == 0, "Must be");
156
157 // Check for overflow.
158 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
159 if (total_reserved < _young_gen_spec->max_size()) {
160 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
161 "the maximum representable size");
162 }
163 assert(total_reserved % alignment == 0,
164 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
165 SIZE_FORMAT, total_reserved, alignment);
166
167 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
168
169 os::trace_page_sizes("Heap",
170 collector_policy()->min_heap_byte_size(),
171 total_reserved,
172 alignment,
173 heap_rs->base(),
174 heap_rs->size());
175
176 return heap_rs->base();
177 }
178
179 namespace {
180 class GenIsScavengable : public BoolObjectClosure {
181 public:
182 bool do_object_b(oop obj) {
183 return GenCollectedHeap::heap()->is_in_young(obj);
184 }
185 };
186
187 GenIsScavengable _is_scavengable;
188 }
189
190 void GenCollectedHeap::post_initialize() {
191 CollectedHeap::post_initialize();
192 ref_processing_init();
193
194 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
195
196 initialize_size_policy(def_new_gen->eden()->capacity(),
197 _old_gen->capacity(),
198 def_new_gen->from()->capacity());
199
200 MarkSweep::initialize();
201
202 ScavengableNMethods::initialize(&_is_scavengable);
203 }
204
205 void GenCollectedHeap::ref_processing_init() {
206 _young_gen->ref_processor_init();
207 _old_gen->ref_processor_init();
208 }
209
210 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
211 return _young_gen_spec;
212 }
213
214 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
215 return _old_gen_spec;
216 }
217
218 size_t GenCollectedHeap::capacity() const {
219 return _young_gen->capacity() + _old_gen->capacity();
220 }
221
222 size_t GenCollectedHeap::used() const {
223 return _young_gen->used() + _old_gen->used();
224 }
225
226 void GenCollectedHeap::save_used_regions() {
227 _old_gen->save_used_region();
228 _young_gen->save_used_region();
229 }
230
231 size_t GenCollectedHeap::max_capacity() const {
232 return _young_gen->max_capacity() + _old_gen->max_capacity();
233 }
234
235 // Update the _full_collections_completed counter
236 // at the end of a stop-world full GC.
237 unsigned int GenCollectedHeap::update_full_collections_completed() {
238 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
239 assert(_full_collections_completed <= _total_full_collections,
240 "Can't complete more collections than were started");
241 _full_collections_completed = _total_full_collections;
242 ml.notify_all();
243 return _full_collections_completed;
244 }
245
246 // Update the _full_collections_completed counter, as appropriate,
247 // at the end of a concurrent GC cycle. Note the conditional update
248 // below to allow this method to be called by a concurrent collector
249 // without synchronizing in any manner with the VM thread (which
250 // may already have initiated a STW full collection "concurrently").
251 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
252 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
253 assert((_full_collections_completed <= _total_full_collections) &&
254 (count <= _total_full_collections),
255 "Can't complete more collections than were started");
256 if (count > _full_collections_completed) {
257 _full_collections_completed = count;
258 ml.notify_all();
259 }
260 return _full_collections_completed;
261 }
262
263 // Return true if any of the following is true:
264 // . the allocation won't fit into the current young gen heap
265 // . gc locker is occupied (jni critical section)
266 // . heap memory is tight -- the most recent previous collection
267 // was a full collection because a partial collection (would
268 // have) failed and is likely to fail again
269 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
270 size_t young_capacity = _young_gen->capacity_before_gc();
271 return (word_size > heap_word_size(young_capacity))
272 || GCLocker::is_active_and_needs_gc()
273 || incremental_collection_failed();
274 }
275
276 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
277 HeapWord* result = NULL;
278 if (_old_gen->should_allocate(size, is_tlab)) {
279 result = _old_gen->expand_and_allocate(size, is_tlab);
280 }
281 if (result == NULL) {
282 if (_young_gen->should_allocate(size, is_tlab)) {
283 result = _young_gen->expand_and_allocate(size, is_tlab);
284 }
285 }
286 assert(result == NULL || is_in_reserved(result), "result not in heap");
287 return result;
288 }
289
290 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
291 bool is_tlab,
292 bool* gc_overhead_limit_was_exceeded) {
293 // In general gc_overhead_limit_was_exceeded should be false so
294 // set it so here and reset it to true only if the gc time
295 // limit is being exceeded as checked below.
296 *gc_overhead_limit_was_exceeded = false;
297
298 HeapWord* result = NULL;
299
300 // Loop until the allocation is satisfied, or unsatisfied after GC.
301 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
302 HandleMark hm; // Discard any handles allocated in each iteration.
303
304 // First allocation attempt is lock-free.
305 Generation *young = _young_gen;
306 assert(young->supports_inline_contig_alloc(),
307 "Otherwise, must do alloc within heap lock");
308 if (young->should_allocate(size, is_tlab)) {
309 result = young->par_allocate(size, is_tlab);
310 if (result != NULL) {
311 assert(is_in_reserved(result), "result not in heap");
312 return result;
313 }
314 }
315 uint gc_count_before; // Read inside the Heap_lock locked region.
316 {
317 MutexLocker ml(Heap_lock);
318 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
319 // Note that only large objects get a shot at being
320 // allocated in later generations.
321 bool first_only = !should_try_older_generation_allocation(size);
322
323 result = attempt_allocation(size, is_tlab, first_only);
324 if (result != NULL) {
325 assert(is_in_reserved(result), "result not in heap");
326 return result;
327 }
328
329 if (GCLocker::is_active_and_needs_gc()) {
330 if (is_tlab) {
331 return NULL; // Caller will retry allocating individual object.
332 }
333 if (!is_maximal_no_gc()) {
334 // Try and expand heap to satisfy request.
335 result = expand_heap_and_allocate(size, is_tlab);
336 // Result could be null if we are out of space.
337 if (result != NULL) {
338 return result;
339 }
340 }
341
342 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
343 return NULL; // We didn't get to do a GC and we didn't get any memory.
344 }
345
346 // If this thread is not in a jni critical section, we stall
347 // the requestor until the critical section has cleared and
348 // GC allowed. When the critical section clears, a GC is
349 // initiated by the last thread exiting the critical section; so
350 // we retry the allocation sequence from the beginning of the loop,
351 // rather than causing more, now probably unnecessary, GC attempts.
352 JavaThread* jthr = JavaThread::current();
353 if (!jthr->in_critical()) {
354 MutexUnlocker mul(Heap_lock);
355 // Wait for JNI critical section to be exited
356 GCLocker::stall_until_clear();
357 gclocker_stalled_count += 1;
358 continue;
359 } else {
360 if (CheckJNICalls) {
361 fatal("Possible deadlock due to allocating while"
362 " in jni critical section");
363 }
364 return NULL;
365 }
366 }
367
368 // Read the gc count while the heap lock is held.
369 gc_count_before = total_collections();
370 }
371
372 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
373 VMThread::execute(&op);
374 if (op.prologue_succeeded()) {
375 result = op.result();
376 if (op.gc_locked()) {
377 assert(result == NULL, "must be NULL if gc_locked() is true");
378 continue; // Retry and/or stall as necessary.
379 }
380
381 // Allocation has failed and a collection
382 // has been done. If the gc time limit was exceeded the
383 // this time, return NULL so that an out-of-memory
384 // will be thrown. Clear gc_overhead_limit_exceeded
385 // so that the overhead exceeded does not persist.
386
387 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
388 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
389
390 if (limit_exceeded && softrefs_clear) {
391 *gc_overhead_limit_was_exceeded = true;
392 size_policy()->set_gc_overhead_limit_exceeded(false);
393 if (op.result() != NULL) {
394 CollectedHeap::fill_with_object(op.result(), size);
395 }
396 return NULL;
397 }
398 assert(result == NULL || is_in_reserved(result),
399 "result not in heap");
400 return result;
401 }
402
403 // Give a warning if we seem to be looping forever.
404 if ((QueuedAllocationWarningCount > 0) &&
405 (try_count % QueuedAllocationWarningCount == 0)) {
406 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
407 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
408 }
409 }
410 }
411
412 #ifndef PRODUCT
413 // Override of memory state checking method in CollectedHeap:
414 // Some collectors (CMS for example) can't have badHeapWordVal written
415 // in the first two words of an object. (For instance , in the case of
416 // CMS these words hold state used to synchronize between certain
417 // (concurrent) GC steps and direct allocating mutators.)
418 // The skip_header_HeapWords() method below, allows us to skip
419 // over the requisite number of HeapWord's. Note that (for
420 // generational collectors) this means that those many words are
421 // skipped in each object, irrespective of the generation in which
422 // that object lives. The resultant loss of precision seems to be
423 // harmless and the pain of avoiding that imprecision appears somewhat
424 // higher than we are prepared to pay for such rudimentary debugging
425 // support.
426 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
427 size_t size) {
428 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
429 // We are asked to check a size in HeapWords,
430 // but the memory is mangled in juint words.
431 juint* start = (juint*) (addr + skip_header_HeapWords());
432 juint* end = (juint*) (addr + size);
433 for (juint* slot = start; slot < end; slot += 1) {
434 assert(*slot == badHeapWordVal,
435 "Found non badHeapWordValue in pre-allocation check");
436 }
437 }
438 }
439 #endif
440
441 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
442 bool is_tlab,
443 bool first_only) {
444 HeapWord* res = NULL;
445
446 if (_young_gen->should_allocate(size, is_tlab)) {
447 res = _young_gen->allocate(size, is_tlab);
448 if (res != NULL || first_only) {
449 return res;
450 }
451 }
452
453 if (_old_gen->should_allocate(size, is_tlab)) {
454 res = _old_gen->allocate(size, is_tlab);
455 }
456
457 return res;
458 }
459
460 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
461 bool* gc_overhead_limit_was_exceeded) {
462 return mem_allocate_work(size,
463 false /* is_tlab */,
464 gc_overhead_limit_was_exceeded);
465 }
466
467 bool GenCollectedHeap::must_clear_all_soft_refs() {
468 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
469 _gc_cause == GCCause::_wb_full_gc;
470 }
471
472 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
473 bool is_tlab, bool run_verification, bool clear_soft_refs,
474 bool restore_marks_for_biased_locking) {
475 FormatBuffer<> title("Collect gen: %s", gen->short_name());
476 GCTraceTime(Trace, gc, phases) t1(title);
477 TraceCollectorStats tcs(gen->counters());
478 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
479
480 gen->stat_record()->invocations++;
481 gen->stat_record()->accumulated_time.start();
482
483 // Must be done anew before each collection because
484 // a previous collection will do mangling and will
485 // change top of some spaces.
486 record_gen_tops_before_GC();
487
488 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
489
490 if (run_verification && VerifyBeforeGC) {
491 HandleMark hm; // Discard invalid handles created during verification
492 Universe::verify("Before GC");
493 }
494 COMPILER2_PRESENT(DerivedPointerTable::clear());
495
496 if (restore_marks_for_biased_locking) {
497 // We perform this mark word preservation work lazily
498 // because it's only at this point that we know whether we
499 // absolutely have to do it; we want to avoid doing it for
500 // scavenge-only collections where it's unnecessary
501 BiasedLocking::preserve_marks();
502 }
503
504 // Do collection work
505 {
506 // Note on ref discovery: For what appear to be historical reasons,
507 // GCH enables and disabled (by enqueing) refs discovery.
508 // In the future this should be moved into the generation's
509 // collect method so that ref discovery and enqueueing concerns
510 // are local to a generation. The collect method could return
511 // an appropriate indication in the case that notification on
512 // the ref lock was needed. This will make the treatment of
513 // weak refs more uniform (and indeed remove such concerns
514 // from GCH). XXX
515
516 HandleMark hm; // Discard invalid handles created during gc
517 save_marks(); // save marks for all gens
518 // We want to discover references, but not process them yet.
519 // This mode is disabled in process_discovered_references if the
520 // generation does some collection work, or in
521 // enqueue_discovered_references if the generation returns
522 // without doing any work.
523 ReferenceProcessor* rp = gen->ref_processor();
524 // If the discovery of ("weak") refs in this generation is
525 // atomic wrt other collectors in this configuration, we
526 // are guaranteed to have empty discovered ref lists.
527 if (rp->discovery_is_atomic()) {
528 rp->enable_discovery();
529 rp->setup_policy(clear_soft_refs);
530 } else {
531 // collect() below will enable discovery as appropriate
532 }
533 gen->collect(full, clear_soft_refs, size, is_tlab);
534 if (!rp->enqueuing_is_done()) {
535 rp->disable_discovery();
536 } else {
537 rp->set_enqueuing_is_done(false);
538 }
539 rp->verify_no_references_recorded();
540 }
541
542 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
543
544 gen->stat_record()->accumulated_time.stop();
545
546 update_gc_stats(gen, full);
547
548 if (run_verification && VerifyAfterGC) {
549 HandleMark hm; // Discard invalid handles created during verification
550 Universe::verify("After GC");
551 }
552 }
553
554 void GenCollectedHeap::do_collection(bool full,
555 bool clear_all_soft_refs,
556 size_t size,
557 bool is_tlab,
558 GenerationType max_generation) {
559 ResourceMark rm;
560 DEBUG_ONLY(Thread* my_thread = Thread::current();)
561
562 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
563 assert(my_thread->is_VM_thread() ||
564 my_thread->is_ConcurrentGC_thread(),
565 "incorrect thread type capability");
566 assert(Heap_lock->is_locked(),
567 "the requesting thread should have the Heap_lock");
568 guarantee(!is_gc_active(), "collection is not reentrant");
569
570 if (GCLocker::check_active_before_gc()) {
571 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
572 }
573
574 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
575 soft_ref_policy()->should_clear_all_soft_refs();
576
577 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
578
579 const size_t metadata_prev_used = MetaspaceUtils::used_bytes();
580
581
582 FlagSetting fl(_is_gc_active, true);
583
584 bool complete = full && (max_generation == OldGen);
585 bool old_collects_young = complete && !ScavengeBeforeFullGC;
586 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
587
588 size_t young_prev_used = _young_gen->used();
589 size_t old_prev_used = _old_gen->used();
590
591 bool run_verification = total_collections() >= VerifyGCStartAt;
592 bool prepared_for_verification = false;
593 bool do_full_collection = false;
594
595 if (do_young_collection) {
596 GCIdMark gc_id_mark;
597 GCTraceCPUTime tcpu;
598 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true);
599
600 print_heap_before_gc();
601
602 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
603 prepare_for_verify();
604 prepared_for_verification = true;
605 }
606
607 gc_prologue(complete);
608 increment_total_collections(complete);
609
610 collect_generation(_young_gen,
611 full,
612 size,
613 is_tlab,
614 run_verification && VerifyGCLevel <= 0,
615 do_clear_all_soft_refs,
616 false);
617
618 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
619 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
620 // Allocation request was met by young GC.
621 size = 0;
622 }
623
624 // Ask if young collection is enough. If so, do the final steps for young collection,
625 // and fallthrough to the end.
626 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
627 if (!do_full_collection) {
628 // Adjust generation sizes.
629 _young_gen->compute_new_size();
630
631 print_heap_change(young_prev_used, old_prev_used);
632 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
633
634 // Track memory usage and detect low memory after GC finishes
635 MemoryService::track_memory_usage();
636
637 gc_epilogue(complete);
638 }
639
640 print_heap_after_gc();
641
642 } else {
643 // No young collection, ask if we need to perform Full collection.
644 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation);
645 }
646
647 if (do_full_collection) {
648 GCIdMark gc_id_mark;
649 GCTraceCPUTime tcpu;
650 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
651
652 print_heap_before_gc();
653
654 if (!prepared_for_verification && run_verification &&
655 VerifyGCLevel <= 1 && VerifyBeforeGC) {
656 prepare_for_verify();
657 }
658
659 if (!do_young_collection) {
660 gc_prologue(complete);
661 increment_total_collections(complete);
662 }
663
664 // Accounting quirk: total full collections would be incremented when "complete"
665 // is set, by calling increment_total_collections above. However, we also need to
666 // account Full collections that had "complete" unset.
667 if (!complete) {
668 increment_total_full_collections();
669 }
670
671 collect_generation(_old_gen,
672 full,
673 size,
674 is_tlab,
675 run_verification && VerifyGCLevel <= 1,
676 do_clear_all_soft_refs,
677 true);
678
679 // Adjust generation sizes.
680 _old_gen->compute_new_size();
681 _young_gen->compute_new_size();
682
683 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
684 ClassLoaderDataGraph::purge();
685 MetaspaceUtils::verify_metrics();
686 // Resize the metaspace capacity after full collections
687 MetaspaceGC::compute_new_size();
688 update_full_collections_completed();
689
690 print_heap_change(young_prev_used, old_prev_used);
691 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
692
693 // Track memory usage and detect low memory after GC finishes
694 MemoryService::track_memory_usage();
695
696 // Need to tell the epilogue code we are done with Full GC, regardless what was
697 // the initial value for "complete" flag.
698 gc_epilogue(true);
699
700 BiasedLocking::restore_marks();
701
702 print_heap_after_gc();
703 }
704
705 #ifdef TRACESPINNING
706 ParallelTaskTerminator::print_termination_counts();
707 #endif
708 }
709
710 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab,
711 GenCollectedHeap::GenerationType max_gen) const {
712 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab);
713 }
714
715 void GenCollectedHeap::register_nmethod(nmethod* nm) {
716 ScavengableNMethods::register_nmethod(nm);
717 }
718
719 void GenCollectedHeap::unregister_nmethod(nmethod* nm) {
720 ScavengableNMethods::unregister_nmethod(nm);
721 }
722
723 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
724 ScavengableNMethods::verify_nmethod(nm);
725 }
726
727 void GenCollectedHeap::flush_nmethod(nmethod* nm) {
728 ScavengableNMethods::flush_nmethod(nm);
729 }
730
731 void GenCollectedHeap::prune_nmethods() {
732 ScavengableNMethods::prune_nmethods();
733 }
734
735 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
736 GCCauseSetter x(this, GCCause::_allocation_failure);
737 HeapWord* result = NULL;
738
739 assert(size != 0, "Precondition violated");
740 if (GCLocker::is_active_and_needs_gc()) {
741 // GC locker is active; instead of a collection we will attempt
742 // to expand the heap, if there's room for expansion.
743 if (!is_maximal_no_gc()) {
744 result = expand_heap_and_allocate(size, is_tlab);
745 }
746 return result; // Could be null if we are out of space.
747 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
748 // Do an incremental collection.
749 do_collection(false, // full
750 false, // clear_all_soft_refs
751 size, // size
752 is_tlab, // is_tlab
753 GenCollectedHeap::OldGen); // max_generation
754 } else {
755 log_trace(gc)(" :: Trying full because partial may fail :: ");
756 // Try a full collection; see delta for bug id 6266275
757 // for the original code and why this has been simplified
758 // with from-space allocation criteria modified and
759 // such allocation moved out of the safepoint path.
760 do_collection(true, // full
761 false, // clear_all_soft_refs
762 size, // size
763 is_tlab, // is_tlab
764 GenCollectedHeap::OldGen); // max_generation
765 }
766
767 result = attempt_allocation(size, is_tlab, false /*first_only*/);
768
769 if (result != NULL) {
770 assert(is_in_reserved(result), "result not in heap");
771 return result;
772 }
773
774 // OK, collection failed, try expansion.
775 result = expand_heap_and_allocate(size, is_tlab);
776 if (result != NULL) {
777 return result;
778 }
779
780 // If we reach this point, we're really out of memory. Try every trick
781 // we can to reclaim memory. Force collection of soft references. Force
782 // a complete compaction of the heap. Any additional methods for finding
783 // free memory should be here, especially if they are expensive. If this
784 // attempt fails, an OOM exception will be thrown.
785 {
786 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
787
788 do_collection(true, // full
789 true, // clear_all_soft_refs
790 size, // size
791 is_tlab, // is_tlab
792 GenCollectedHeap::OldGen); // max_generation
793 }
794
795 result = attempt_allocation(size, is_tlab, false /* first_only */);
796 if (result != NULL) {
797 assert(is_in_reserved(result), "result not in heap");
798 return result;
799 }
800
801 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
802 "Flag should have been handled and cleared prior to this point");
803
804 // What else? We might try synchronous finalization later. If the total
805 // space available is large enough for the allocation, then a more
806 // complete compaction phase than we've tried so far might be
807 // appropriate.
808 return NULL;
809 }
810
811 #ifdef ASSERT
812 class AssertNonScavengableClosure: public OopClosure {
813 public:
814 virtual void do_oop(oop* p) {
815 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
816 "Referent should not be scavengable."); }
817 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
818 };
819 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
820 #endif
821
822 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
823 ScanningOption so,
824 OopClosure* strong_roots,
825 CLDClosure* strong_cld_closure,
826 CLDClosure* weak_cld_closure,
827 CodeBlobToOopClosure* code_roots) {
828 // General roots.
829 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
830 assert(code_roots != NULL, "code root closure should always be set");
831 // _n_termination for _process_strong_tasks should be set up stream
832 // in a method not running in a GC worker. Otherwise the GC worker
833 // could be trying to change the termination condition while the task
834 // is executing in another GC worker.
835
836 if (_process_strong_tasks->try_claim_task(GCH_PS_ClassLoaderDataGraph_oops_do)) {
837 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
838 }
839
840 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
841 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
842
843 bool is_par = scope->n_threads() > 1;
844 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
845
846 if (_process_strong_tasks->try_claim_task(GCH_PS_Universe_oops_do)) {
847 Universe::oops_do(strong_roots);
848 }
849 // Global (strong) JNI handles
850 if (_process_strong_tasks->try_claim_task(GCH_PS_JNIHandles_oops_do)) {
851 JNIHandles::oops_do(strong_roots);
852 }
853
854 if (_process_strong_tasks->try_claim_task(GCH_PS_ObjectSynchronizer_oops_do)) {
855 ObjectSynchronizer::oops_do(strong_roots);
856 }
857 if (_process_strong_tasks->try_claim_task(GCH_PS_Management_oops_do)) {
858 Management::oops_do(strong_roots);
859 }
860 if (_process_strong_tasks->try_claim_task(GCH_PS_jvmti_oops_do)) {
861 JvmtiExport::oops_do(strong_roots);
862 }
863 if (UseAOT && _process_strong_tasks->try_claim_task(GCH_PS_aot_oops_do)) {
864 AOTLoader::oops_do(strong_roots);
865 }
866
867 if (_process_strong_tasks->try_claim_task(GCH_PS_SystemDictionary_oops_do)) {
868 SystemDictionary::oops_do(strong_roots);
869 }
870
871 if (_process_strong_tasks->try_claim_task(GCH_PS_CodeCache_oops_do)) {
872 if (so & SO_ScavengeCodeCache) {
873 assert(code_roots != NULL, "must supply closure for code cache");
874
875 // We only visit parts of the CodeCache when scavenging.
876 ScavengableNMethods::scavengable_nmethods_do(code_roots);
877 }
878 if (so & SO_AllCodeCache) {
879 assert(code_roots != NULL, "must supply closure for code cache");
880
881 // CMSCollector uses this to do intermediate-strength collections.
882 // We scan the entire code cache, since CodeCache::do_unloading is not called.
883 CodeCache::blobs_do(code_roots);
884 }
885 // Verify that the code cache contents are not subject to
886 // movement by a scavenging collection.
887 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
888 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
889 }
890 }
891
892 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
893 OopsInGenClosure* root_closure,
894 OopsInGenClosure* old_gen_closure,
895 CLDClosure* cld_closure) {
896 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
897
898 process_roots(scope, SO_ScavengeCodeCache, root_closure,
899 cld_closure, cld_closure, &mark_code_closure);
900
901 if (_process_strong_tasks->try_claim_task(GCH_PS_younger_gens)) {
902 root_closure->reset_generation();
903 }
904
905 // When collection is parallel, all threads get to cooperate to do
906 // old generation scanning.
907 old_gen_closure->set_generation(_old_gen);
908 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
909 old_gen_closure->reset_generation();
910
911 _process_strong_tasks->all_tasks_completed(scope->n_threads());
912 }
913
914 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
915 bool is_adjust_phase,
916 ScanningOption so,
917 bool only_strong_roots,
918 OopsInGenClosure* root_closure,
919 CLDClosure* cld_closure) {
920 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
921 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
922
923 process_roots(scope, so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
924 _process_strong_tasks->all_tasks_completed(scope->n_threads());
925 }
926
927 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
928 WeakProcessor::oops_do(root_closure);
929 _young_gen->ref_processor()->weak_oops_do(root_closure);
930 _old_gen->ref_processor()->weak_oops_do(root_closure);
931 }
932
933 bool GenCollectedHeap::no_allocs_since_save_marks() {
934 return _young_gen->no_allocs_since_save_marks() &&
935 _old_gen->no_allocs_since_save_marks();
936 }
937
938 bool GenCollectedHeap::supports_inline_contig_alloc() const {
939 return _young_gen->supports_inline_contig_alloc();
940 }
941
942 HeapWord* volatile* GenCollectedHeap::top_addr() const {
943 return _young_gen->top_addr();
944 }
945
946 HeapWord** GenCollectedHeap::end_addr() const {
947 return _young_gen->end_addr();
948 }
949
950 // public collection interfaces
951
952 void GenCollectedHeap::collect(GCCause::Cause cause) {
953 if (cause == GCCause::_wb_young_gc) {
954 // Young collection for the WhiteBox API.
955 collect(cause, YoungGen);
956 } else {
957 #ifdef ASSERT
958 if (cause == GCCause::_scavenge_alot) {
959 // Young collection only.
960 collect(cause, YoungGen);
961 } else {
962 // Stop-the-world full collection.
963 collect(cause, OldGen);
964 }
965 #else
966 // Stop-the-world full collection.
967 collect(cause, OldGen);
968 #endif
969 }
970 }
971
972 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
973 // The caller doesn't have the Heap_lock
974 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
975 MutexLocker ml(Heap_lock);
976 collect_locked(cause, max_generation);
977 }
978
979 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
980 // The caller has the Heap_lock
981 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
982 collect_locked(cause, OldGen);
983 }
984
985 // this is the private collection interface
986 // The Heap_lock is expected to be held on entry.
987
988 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
989 // Read the GC count while holding the Heap_lock
990 unsigned int gc_count_before = total_collections();
991 unsigned int full_gc_count_before = total_full_collections();
992 {
993 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
994 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
995 cause, max_generation);
996 VMThread::execute(&op);
997 }
998 }
999
1000 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1001 do_full_collection(clear_all_soft_refs, OldGen);
1002 }
1003
1004 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
1005 GenerationType last_generation) {
1006 GenerationType local_last_generation;
1007 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
1008 gc_cause() == GCCause::_gc_locker) {
1009 local_last_generation = YoungGen;
1010 } else {
1011 local_last_generation = last_generation;
1012 }
1013
1014 do_collection(true, // full
1015 clear_all_soft_refs, // clear_all_soft_refs
1016 0, // size
1017 false, // is_tlab
1018 local_last_generation); // last_generation
1019 // Hack XXX FIX ME !!!
1020 // A scavenge may not have been attempted, or may have
1021 // been attempted and failed, because the old gen was too full
1022 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1023 incremental_collection_will_fail(false /* don't consult_young */)) {
1024 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1025 // This time allow the old gen to be collected as well
1026 do_collection(true, // full
1027 clear_all_soft_refs, // clear_all_soft_refs
1028 0, // size
1029 false, // is_tlab
1030 OldGen); // last_generation
1031 }
1032 }
1033
1034 bool GenCollectedHeap::is_in_young(oop p) {
1035 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1036 assert(result == _young_gen->is_in_reserved(p),
1037 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1038 return result;
1039 }
1040
1041 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1042 bool GenCollectedHeap::is_in(const void* p) const {
1043 return _young_gen->is_in(p) || _old_gen->is_in(p);
1044 }
1045
1046 #ifdef ASSERT
1047 // Don't implement this by using is_in_young(). This method is used
1048 // in some cases to check that is_in_young() is correct.
1049 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1050 assert(is_in_reserved(p) || p == NULL,
1051 "Does not work if address is non-null and outside of the heap");
1052 return p < _young_gen->reserved().end() && p != NULL;
1053 }
1054 #endif
1055
1056 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) {
1057 _young_gen->oop_iterate(cl);
1058 _old_gen->oop_iterate(cl);
1059 }
1060
1061 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1062 _young_gen->object_iterate(cl);
1063 _old_gen->object_iterate(cl);
1064 }
1065
1066 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1067 _young_gen->safe_object_iterate(cl);
1068 _old_gen->safe_object_iterate(cl);
1069 }
1070
1071 Space* GenCollectedHeap::space_containing(const void* addr) const {
1072 Space* res = _young_gen->space_containing(addr);
1073 if (res != NULL) {
1074 return res;
1075 }
1076 res = _old_gen->space_containing(addr);
1077 assert(res != NULL, "Could not find containing space");
1078 return res;
1079 }
1080
1081 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1082 assert(is_in_reserved(addr), "block_start of address outside of heap");
1083 if (_young_gen->is_in_reserved(addr)) {
1084 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1085 return _young_gen->block_start(addr);
1086 }
1087
1088 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1089 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1090 return _old_gen->block_start(addr);
1091 }
1092
1093 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1094 assert(is_in_reserved(addr), "block_size of address outside of heap");
1095 if (_young_gen->is_in_reserved(addr)) {
1096 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1097 return _young_gen->block_size(addr);
1098 }
1099
1100 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1101 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1102 return _old_gen->block_size(addr);
1103 }
1104
1105 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1106 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1107 assert(block_start(addr) == addr, "addr must be a block start");
1108 if (_young_gen->is_in_reserved(addr)) {
1109 return _young_gen->block_is_obj(addr);
1110 }
1111
1112 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1113 return _old_gen->block_is_obj(addr);
1114 }
1115
1116 bool GenCollectedHeap::supports_tlab_allocation() const {
1117 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1118 return _young_gen->supports_tlab_allocation();
1119 }
1120
1121 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1122 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1123 if (_young_gen->supports_tlab_allocation()) {
1124 return _young_gen->tlab_capacity();
1125 }
1126 return 0;
1127 }
1128
1129 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1130 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1131 if (_young_gen->supports_tlab_allocation()) {
1132 return _young_gen->tlab_used();
1133 }
1134 return 0;
1135 }
1136
1137 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1138 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1139 if (_young_gen->supports_tlab_allocation()) {
1140 return _young_gen->unsafe_max_tlab_alloc();
1141 }
1142 return 0;
1143 }
1144
1145 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1146 size_t requested_size,
1147 size_t* actual_size) {
1148 bool gc_overhead_limit_was_exceeded;
1149 HeapWord* result = mem_allocate_work(requested_size /* size */,
1150 true /* is_tlab */,
1151 &gc_overhead_limit_was_exceeded);
1152 if (result != NULL) {
1153 *actual_size = requested_size;
1154 }
1155
1156 return result;
1157 }
1158
1159 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1160 // from the list headed by "*prev_ptr".
1161 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1162 bool first = true;
1163 size_t min_size = 0; // "first" makes this conceptually infinite.
1164 ScratchBlock **smallest_ptr, *smallest;
1165 ScratchBlock *cur = *prev_ptr;
1166 while (cur) {
1167 assert(*prev_ptr == cur, "just checking");
1168 if (first || cur->num_words < min_size) {
1169 smallest_ptr = prev_ptr;
1170 smallest = cur;
1171 min_size = smallest->num_words;
1172 first = false;
1173 }
1174 prev_ptr = &cur->next;
1175 cur = cur->next;
1176 }
1177 smallest = *smallest_ptr;
1178 *smallest_ptr = smallest->next;
1179 return smallest;
1180 }
1181
1182 // Sort the scratch block list headed by res into decreasing size order,
1183 // and set "res" to the result.
1184 static void sort_scratch_list(ScratchBlock*& list) {
1185 ScratchBlock* sorted = NULL;
1186 ScratchBlock* unsorted = list;
1187 while (unsorted) {
1188 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1189 smallest->next = sorted;
1190 sorted = smallest;
1191 }
1192 list = sorted;
1193 }
1194
1195 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1196 size_t max_alloc_words) {
1197 ScratchBlock* res = NULL;
1198 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1199 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1200 sort_scratch_list(res);
1201 return res;
1202 }
1203
1204 void GenCollectedHeap::release_scratch() {
1205 _young_gen->reset_scratch();
1206 _old_gen->reset_scratch();
1207 }
1208
1209 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1210 void do_generation(Generation* gen) {
1211 gen->prepare_for_verify();
1212 }
1213 };
1214
1215 void GenCollectedHeap::prepare_for_verify() {
1216 ensure_parsability(false); // no need to retire TLABs
1217 GenPrepareForVerifyClosure blk;
1218 generation_iterate(&blk, false);
1219 }
1220
1221 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1222 bool old_to_young) {
1223 if (old_to_young) {
1224 cl->do_generation(_old_gen);
1225 cl->do_generation(_young_gen);
1226 } else {
1227 cl->do_generation(_young_gen);
1228 cl->do_generation(_old_gen);
1229 }
1230 }
1231
1232 bool GenCollectedHeap::is_maximal_no_gc() const {
1233 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1234 }
1235
1236 void GenCollectedHeap::save_marks() {
1237 _young_gen->save_marks();
1238 _old_gen->save_marks();
1239 }
1240
1241 GenCollectedHeap* GenCollectedHeap::heap() {
1242 CollectedHeap* heap = Universe::heap();
1243 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1244 assert(heap->kind() == CollectedHeap::Serial ||
1245 heap->kind() == CollectedHeap::CMS, "Invalid name");
1246 return (GenCollectedHeap*) heap;
1247 }
1248
1249 #if INCLUDE_SERIALGC
1250 void GenCollectedHeap::prepare_for_compaction() {
1251 // Start by compacting into same gen.
1252 CompactPoint cp(_old_gen);
1253 _old_gen->prepare_for_compaction(&cp);
1254 _young_gen->prepare_for_compaction(&cp);
1255 }
1256 #endif // INCLUDE_SERIALGC
1257
1258 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1259 log_debug(gc, verify)("%s", _old_gen->name());
1260 _old_gen->verify();
1261
1262 log_debug(gc, verify)("%s", _old_gen->name());
1263 _young_gen->verify();
1264
1265 log_debug(gc, verify)("RemSet");
1266 rem_set()->verify();
1267 }
1268
1269 void GenCollectedHeap::print_on(outputStream* st) const {
1270 _young_gen->print_on(st);
1271 _old_gen->print_on(st);
1272 MetaspaceUtils::print_on(st);
1273 }
1274
1275 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1276 }
1277
1278 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1279 }
1280
1281 void GenCollectedHeap::print_tracing_info() const {
1282 if (log_is_enabled(Debug, gc, heap, exit)) {
1283 LogStreamHandle(Debug, gc, heap, exit) lsh;
1284 _young_gen->print_summary_info_on(&lsh);
1285 _old_gen->print_summary_info_on(&lsh);
1286 }
1287 }
1288
1289 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1290 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1291 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1292 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1293 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1294 }
1295
1296 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1297 private:
1298 bool _full;
1299 public:
1300 void do_generation(Generation* gen) {
1301 gen->gc_prologue(_full);
1302 }
1303 GenGCPrologueClosure(bool full) : _full(full) {};
1304 };
1305
1306 void GenCollectedHeap::gc_prologue(bool full) {
1307 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1308
1309 // Fill TLAB's and such
1310 ensure_parsability(true); // retire TLABs
1311
1312 // Walk generations
1313 GenGCPrologueClosure blk(full);
1314 generation_iterate(&blk, false); // not old-to-young.
1315 };
1316
1317 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1318 private:
1319 bool _full;
1320 public:
1321 void do_generation(Generation* gen) {
1322 gen->gc_epilogue(_full);
1323 }
1324 GenGCEpilogueClosure(bool full) : _full(full) {};
1325 };
1326
1327 void GenCollectedHeap::gc_epilogue(bool full) {
1328 #if COMPILER2_OR_JVMCI
1329 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1330 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1331 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1332 #endif // COMPILER2_OR_JVMCI
1333
1334 resize_all_tlabs();
1335
1336 GenGCEpilogueClosure blk(full);
1337 generation_iterate(&blk, false); // not old-to-young.
1338
1339 if (!CleanChunkPoolAsync) {
1340 Chunk::clean_chunk_pool();
1341 }
1342
1343 MetaspaceCounters::update_performance_counters();
1344 CompressedClassSpaceCounters::update_performance_counters();
1345 };
1346
1347 #ifndef PRODUCT
1348 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1349 private:
1350 public:
1351 void do_generation(Generation* gen) {
1352 gen->record_spaces_top();
1353 }
1354 };
1355
1356 void GenCollectedHeap::record_gen_tops_before_GC() {
1357 if (ZapUnusedHeapArea) {
1358 GenGCSaveTopsBeforeGCClosure blk;
1359 generation_iterate(&blk, false); // not old-to-young.
1360 }
1361 }
1362 #endif // not PRODUCT
1363
1364 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1365 public:
1366 void do_generation(Generation* gen) {
1367 gen->ensure_parsability();
1368 }
1369 };
1370
1371 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1372 CollectedHeap::ensure_parsability(retire_tlabs);
1373 GenEnsureParsabilityClosure ep_cl;
1374 generation_iterate(&ep_cl, false);
1375 }
1376
1377 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1378 oop obj,
1379 size_t obj_size) {
1380 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1381 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1382 HeapWord* result = NULL;
1383
1384 result = old_gen->expand_and_allocate(obj_size, false);
1385
1386 if (result != NULL) {
1387 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1388 }
1389 return oop(result);
1390 }
1391
1392 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1393 jlong _time; // in ms
1394 jlong _now; // in ms
1395
1396 public:
1397 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1398
1399 jlong time() { return _time; }
1400
1401 void do_generation(Generation* gen) {
1402 _time = MIN2(_time, gen->time_of_last_gc(_now));
1403 }
1404 };
1405
1406 jlong GenCollectedHeap::millis_since_last_gc() {
1407 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1408 // provided the underlying platform provides such a time source
1409 // (and it is bug free). So we still have to guard against getting
1410 // back a time later than 'now'.
1411 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1412 GenTimeOfLastGCClosure tolgc_cl(now);
1413 // iterate over generations getting the oldest
1414 // time that a generation was collected
1415 generation_iterate(&tolgc_cl, false);
1416
1417 jlong retVal = now - tolgc_cl.time();
1418 if (retVal < 0) {
1419 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1420 ". returning zero instead.", retVal);
1421 return 0;
1422 }
1423 return retVal;
1424 }