1 /*
2 * Copyright (c) 2000, 2018, 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/symbolTable.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/icBuffer.hpp"
33 #include "gc/serial/defNewGeneration.hpp"
34 #include "gc/shared/adaptiveSizePolicy.hpp"
35 #include "gc/shared/cardTableBarrierSet.hpp"
36 #include "gc/shared/cardTableRS.hpp"
37 #include "gc/shared/collectedHeap.inline.hpp"
38 #include "gc/shared/collectorCounters.hpp"
39 #include "gc/shared/gcId.hpp"
40 #include "gc/shared/gcLocker.hpp"
41 #include "gc/shared/gcPolicyCounters.hpp"
42 #include "gc/shared/gcTrace.hpp"
43 #include "gc/shared/gcTraceTime.inline.hpp"
44 #include "gc/shared/genCollectedHeap.hpp"
45 #include "gc/shared/genOopClosures.inline.hpp"
46 #include "gc/shared/generationSpec.hpp"
47 #include "gc/shared/space.hpp"
48 #include "gc/shared/strongRootsScope.hpp"
49 #include "gc/shared/vmGCOperations.hpp"
50 #include "gc/shared/weakProcessor.hpp"
51 #include "gc/shared/workgroup.hpp"
52 #include "memory/filemap.hpp"
53 #include "memory/metaspaceCounters.hpp"
54 #include "memory/resourceArea.hpp"
55 #include "oops/oop.inline.hpp"
56 #include "runtime/biasedLocking.hpp"
57 #include "runtime/flags/flagSetting.hpp"
58 #include "runtime/handles.hpp"
59 #include "runtime/handles.inline.hpp"
60 #include "runtime/java.hpp"
61 #include "runtime/vmThread.hpp"
62 #include "services/management.hpp"
63 #include "services/memoryService.hpp"
64 #include "utilities/debug.hpp"
65 #include "utilities/formatBuffer.hpp"
66 #include "utilities/macros.hpp"
67 #include "utilities/stack.inline.hpp"
68 #include "utilities/vmError.hpp"
69
70 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy,
71 Generation::Name young,
72 Generation::Name old,
73 const char* policy_counters_name) :
74 CollectedHeap(),
75 _rem_set(NULL),
76 _young_gen_spec(new GenerationSpec(young,
77 policy->initial_young_size(),
78 policy->max_young_size(),
79 policy->gen_alignment())),
80 _old_gen_spec(new GenerationSpec(old,
81 policy->initial_old_size(),
82 policy->max_old_size(),
83 policy->gen_alignment())),
84 _gen_policy(policy),
85 _soft_ref_gen_policy(),
86 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
87 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
88 _full_collections_completed(0) {
89 }
90
91 jint GenCollectedHeap::initialize() {
92 // While there are no constraints in the GC code that HeapWordSize
93 // be any particular value, there are multiple other areas in the
94 // system which believe this to be true (e.g. oop->object_size in some
95 // cases incorrectly returns the size in wordSize units rather than
96 // HeapWordSize).
97 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
98
99 // Allocate space for the heap.
100
101 char* heap_address;
102 ReservedSpace heap_rs;
103
104 size_t heap_alignment = collector_policy()->heap_alignment();
105
106 heap_address = allocate(heap_alignment, &heap_rs);
107
108 if (!heap_rs.is_reserved()) {
109 vm_shutdown_during_initialization(
110 "Could not reserve enough space for object heap");
111 return JNI_ENOMEM;
112 }
113
114 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
115
116 _rem_set = create_rem_set(reserved_region());
117 _rem_set->initialize();
118 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
119 bs->initialize();
120 BarrierSet::set_barrier_set(bs);
121
122 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false);
123 _young_gen = _young_gen_spec->init(young_rs, rem_set());
124 heap_rs = heap_rs.last_part(_young_gen_spec->max_size());
125
126 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false);
127 _old_gen = _old_gen_spec->init(old_rs, rem_set());
128 clear_incremental_collection_failed();
129
130 return JNI_OK;
131 }
132
133 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
134 return new CardTableRS(reserved_region, false /* scan_concurrently */);
135 }
136
137 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
138 size_t init_promo_size,
139 size_t init_survivor_size) {
140 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
141 _size_policy = new AdaptiveSizePolicy(init_eden_size,
142 init_promo_size,
143 init_survivor_size,
144 max_gc_pause_sec,
145 GCTimeRatio);
146 }
147
148 char* GenCollectedHeap::allocate(size_t alignment,
149 ReservedSpace* heap_rs){
150 // Now figure out the total size.
151 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
152 assert(alignment % pageSize == 0, "Must be");
153
154 // Check for overflow.
155 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
156 if (total_reserved < _young_gen_spec->max_size()) {
157 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
158 "the maximum representable size");
159 }
160 assert(total_reserved % alignment == 0,
161 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
162 SIZE_FORMAT, total_reserved, alignment);
163
164 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
165
166 os::trace_page_sizes("Heap",
167 collector_policy()->min_heap_byte_size(),
168 total_reserved,
169 alignment,
170 heap_rs->base(),
171 heap_rs->size());
172
173 return heap_rs->base();
174 }
175
176 void GenCollectedHeap::post_initialize() {
177 CollectedHeap::post_initialize();
178 ref_processing_init();
179
180 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
181
182 initialize_size_policy(def_new_gen->eden()->capacity(),
183 _old_gen->capacity(),
184 def_new_gen->from()->capacity());
185
186 MarkSweep::initialize();
187 }
188
189 void GenCollectedHeap::ref_processing_init() {
190 _young_gen->ref_processor_init();
191 _old_gen->ref_processor_init();
192 }
193
194 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
195 return _young_gen_spec;
196 }
197
198 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
199 return _old_gen_spec;
200 }
201
202 size_t GenCollectedHeap::capacity() const {
203 return _young_gen->capacity() + _old_gen->capacity();
204 }
205
206 size_t GenCollectedHeap::used() const {
207 return _young_gen->used() + _old_gen->used();
208 }
209
210 void GenCollectedHeap::save_used_regions() {
211 _old_gen->save_used_region();
212 _young_gen->save_used_region();
213 }
214
215 size_t GenCollectedHeap::max_capacity() const {
216 return _young_gen->max_capacity() + _old_gen->max_capacity();
217 }
218
219 // Update the _full_collections_completed counter
220 // at the end of a stop-world full GC.
221 unsigned int GenCollectedHeap::update_full_collections_completed() {
222 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
223 assert(_full_collections_completed <= _total_full_collections,
224 "Can't complete more collections than were started");
225 _full_collections_completed = _total_full_collections;
226 ml.notify_all();
227 return _full_collections_completed;
228 }
229
230 // Update the _full_collections_completed counter, as appropriate,
231 // at the end of a concurrent GC cycle. Note the conditional update
232 // below to allow this method to be called by a concurrent collector
233 // without synchronizing in any manner with the VM thread (which
234 // may already have initiated a STW full collection "concurrently").
235 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
236 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
237 assert((_full_collections_completed <= _total_full_collections) &&
238 (count <= _total_full_collections),
239 "Can't complete more collections than were started");
240 if (count > _full_collections_completed) {
241 _full_collections_completed = count;
242 ml.notify_all();
243 }
244 return _full_collections_completed;
245 }
246
247 // Return true if any of the following is true:
248 // . the allocation won't fit into the current young gen heap
249 // . gc locker is occupied (jni critical section)
250 // . heap memory is tight -- the most recent previous collection
251 // was a full collection because a partial collection (would
252 // have) failed and is likely to fail again
253 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
254 size_t young_capacity = _young_gen->capacity_before_gc();
255 return (word_size > heap_word_size(young_capacity))
256 || GCLocker::is_active_and_needs_gc()
257 || incremental_collection_failed();
258 }
259
260 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
261 HeapWord* result = NULL;
262 if (_old_gen->should_allocate(size, is_tlab)) {
263 result = _old_gen->expand_and_allocate(size, is_tlab);
264 }
265 if (result == NULL) {
266 if (_young_gen->should_allocate(size, is_tlab)) {
267 result = _young_gen->expand_and_allocate(size, is_tlab);
268 }
269 }
270 assert(result == NULL || is_in_reserved(result), "result not in heap");
271 return result;
272 }
273
274 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
275 bool is_tlab,
276 bool* gc_overhead_limit_was_exceeded) {
277 debug_only(check_for_valid_allocation_state());
278 assert(no_gc_in_progress(), "Allocation during gc not allowed");
279
280 // In general gc_overhead_limit_was_exceeded should be false so
281 // set it so here and reset it to true only if the gc time
282 // limit is being exceeded as checked below.
283 *gc_overhead_limit_was_exceeded = false;
284
285 HeapWord* result = NULL;
286
287 // Loop until the allocation is satisfied, or unsatisfied after GC.
288 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
289 HandleMark hm; // Discard any handles allocated in each iteration.
290
291 // First allocation attempt is lock-free.
292 Generation *young = _young_gen;
293 assert(young->supports_inline_contig_alloc(),
294 "Otherwise, must do alloc within heap lock");
295 if (young->should_allocate(size, is_tlab)) {
296 result = young->par_allocate(size, is_tlab);
297 if (result != NULL) {
298 assert(is_in_reserved(result), "result not in heap");
299 return result;
300 }
301 }
302 uint gc_count_before; // Read inside the Heap_lock locked region.
303 {
304 MutexLocker ml(Heap_lock);
305 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
306 // Note that only large objects get a shot at being
307 // allocated in later generations.
308 bool first_only = !should_try_older_generation_allocation(size);
309
310 result = attempt_allocation(size, is_tlab, first_only);
311 if (result != NULL) {
312 assert(is_in_reserved(result), "result not in heap");
313 return result;
314 }
315
316 if (GCLocker::is_active_and_needs_gc()) {
317 if (is_tlab) {
318 return NULL; // Caller will retry allocating individual object.
319 }
320 if (!is_maximal_no_gc()) {
321 // Try and expand heap to satisfy request.
322 result = expand_heap_and_allocate(size, is_tlab);
323 // Result could be null if we are out of space.
324 if (result != NULL) {
325 return result;
326 }
327 }
328
329 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
330 return NULL; // We didn't get to do a GC and we didn't get any memory.
331 }
332
333 // If this thread is not in a jni critical section, we stall
334 // the requestor until the critical section has cleared and
335 // GC allowed. When the critical section clears, a GC is
336 // initiated by the last thread exiting the critical section; so
337 // we retry the allocation sequence from the beginning of the loop,
338 // rather than causing more, now probably unnecessary, GC attempts.
339 JavaThread* jthr = JavaThread::current();
340 if (!jthr->in_critical()) {
341 MutexUnlocker mul(Heap_lock);
342 // Wait for JNI critical section to be exited
343 GCLocker::stall_until_clear();
344 gclocker_stalled_count += 1;
345 continue;
346 } else {
347 if (CheckJNICalls) {
348 fatal("Possible deadlock due to allocating while"
349 " in jni critical section");
350 }
351 return NULL;
352 }
353 }
354
355 // Read the gc count while the heap lock is held.
356 gc_count_before = total_collections();
357 }
358
359 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
360 VMThread::execute(&op);
361 if (op.prologue_succeeded()) {
362 result = op.result();
363 if (op.gc_locked()) {
364 assert(result == NULL, "must be NULL if gc_locked() is true");
365 continue; // Retry and/or stall as necessary.
366 }
367
368 // Allocation has failed and a collection
369 // has been done. If the gc time limit was exceeded the
370 // this time, return NULL so that an out-of-memory
371 // will be thrown. Clear gc_overhead_limit_exceeded
372 // so that the overhead exceeded does not persist.
373
374 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
375 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
376
377 if (limit_exceeded && softrefs_clear) {
378 *gc_overhead_limit_was_exceeded = true;
379 size_policy()->set_gc_overhead_limit_exceeded(false);
380 if (op.result() != NULL) {
381 CollectedHeap::fill_with_object(op.result(), size);
382 }
383 return NULL;
384 }
385 assert(result == NULL || is_in_reserved(result),
386 "result not in heap");
387 return result;
388 }
389
390 // Give a warning if we seem to be looping forever.
391 if ((QueuedAllocationWarningCount > 0) &&
392 (try_count % QueuedAllocationWarningCount == 0)) {
393 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
394 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
395 }
396 }
397 }
398
399 #ifndef PRODUCT
400 // Override of memory state checking method in CollectedHeap:
401 // Some collectors (CMS for example) can't have badHeapWordVal written
402 // in the first two words of an object. (For instance , in the case of
403 // CMS these words hold state used to synchronize between certain
404 // (concurrent) GC steps and direct allocating mutators.)
405 // The skip_header_HeapWords() method below, allows us to skip
406 // over the requisite number of HeapWord's. Note that (for
407 // generational collectors) this means that those many words are
408 // skipped in each object, irrespective of the generation in which
409 // that object lives. The resultant loss of precision seems to be
410 // harmless and the pain of avoiding that imprecision appears somewhat
411 // higher than we are prepared to pay for such rudimentary debugging
412 // support.
413 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
414 size_t size) {
415 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
416 // We are asked to check a size in HeapWords,
417 // but the memory is mangled in juint words.
418 juint* start = (juint*) (addr + skip_header_HeapWords());
419 juint* end = (juint*) (addr + size);
420 for (juint* slot = start; slot < end; slot += 1) {
421 assert(*slot == badHeapWordVal,
422 "Found non badHeapWordValue in pre-allocation check");
423 }
424 }
425 }
426 #endif
427
428 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
429 bool is_tlab,
430 bool first_only) {
431 HeapWord* res = NULL;
432
433 if (_young_gen->should_allocate(size, is_tlab)) {
434 res = _young_gen->allocate(size, is_tlab);
435 if (res != NULL || first_only) {
436 return res;
437 }
438 }
439
440 if (_old_gen->should_allocate(size, is_tlab)) {
441 res = _old_gen->allocate(size, is_tlab);
442 }
443
444 return res;
445 }
446
447 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
448 bool* gc_overhead_limit_was_exceeded) {
449 return mem_allocate_work(size,
450 false /* is_tlab */,
451 gc_overhead_limit_was_exceeded);
452 }
453
454 bool GenCollectedHeap::must_clear_all_soft_refs() {
455 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
456 _gc_cause == GCCause::_wb_full_gc;
457 }
458
459 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
460 bool is_tlab, bool run_verification, bool clear_soft_refs,
461 bool restore_marks_for_biased_locking) {
462 FormatBuffer<> title("Collect gen: %s", gen->short_name());
463 GCTraceTime(Trace, gc, phases) t1(title);
464 TraceCollectorStats tcs(gen->counters());
465 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
466
467 gen->stat_record()->invocations++;
468 gen->stat_record()->accumulated_time.start();
469
470 // Must be done anew before each collection because
471 // a previous collection will do mangling and will
472 // change top of some spaces.
473 record_gen_tops_before_GC();
474
475 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
476
477 if (run_verification && VerifyBeforeGC) {
478 HandleMark hm; // Discard invalid handles created during verification
479 Universe::verify("Before GC");
480 }
481 COMPILER2_PRESENT(DerivedPointerTable::clear());
482
483 if (restore_marks_for_biased_locking) {
484 // We perform this mark word preservation work lazily
485 // because it's only at this point that we know whether we
486 // absolutely have to do it; we want to avoid doing it for
487 // scavenge-only collections where it's unnecessary
488 BiasedLocking::preserve_marks();
489 }
490
491 // Do collection work
492 {
493 // Note on ref discovery: For what appear to be historical reasons,
494 // GCH enables and disabled (by enqueing) refs discovery.
495 // In the future this should be moved into the generation's
496 // collect method so that ref discovery and enqueueing concerns
497 // are local to a generation. The collect method could return
498 // an appropriate indication in the case that notification on
499 // the ref lock was needed. This will make the treatment of
500 // weak refs more uniform (and indeed remove such concerns
501 // from GCH). XXX
502
503 HandleMark hm; // Discard invalid handles created during gc
504 save_marks(); // save marks for all gens
505 // We want to discover references, but not process them yet.
506 // This mode is disabled in process_discovered_references if the
507 // generation does some collection work, or in
508 // enqueue_discovered_references if the generation returns
509 // without doing any work.
510 ReferenceProcessor* rp = gen->ref_processor();
511 // If the discovery of ("weak") refs in this generation is
512 // atomic wrt other collectors in this configuration, we
513 // are guaranteed to have empty discovered ref lists.
514 if (rp->discovery_is_atomic()) {
515 rp->enable_discovery();
516 rp->setup_policy(clear_soft_refs);
517 } else {
518 // collect() below will enable discovery as appropriate
519 }
520 gen->collect(full, clear_soft_refs, size, is_tlab);
521 if (!rp->enqueuing_is_done()) {
522 rp->disable_discovery();
523 } else {
524 rp->set_enqueuing_is_done(false);
525 }
526 rp->verify_no_references_recorded();
527 }
528
529 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
530
531 gen->stat_record()->accumulated_time.stop();
532
533 update_gc_stats(gen, full);
534
535 if (run_verification && VerifyAfterGC) {
536 HandleMark hm; // Discard invalid handles created during verification
537 Universe::verify("After GC");
538 }
539 }
540
541 void GenCollectedHeap::do_collection(bool full,
542 bool clear_all_soft_refs,
543 size_t size,
544 bool is_tlab,
545 GenerationType max_generation) {
546 ResourceMark rm;
547 DEBUG_ONLY(Thread* my_thread = Thread::current();)
548
549 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
550 assert(my_thread->is_VM_thread() ||
551 my_thread->is_ConcurrentGC_thread(),
552 "incorrect thread type capability");
553 assert(Heap_lock->is_locked(),
554 "the requesting thread should have the Heap_lock");
555 guarantee(!is_gc_active(), "collection is not reentrant");
556
557 if (GCLocker::check_active_before_gc()) {
558 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
559 }
560
561 GCIdMark gc_id_mark;
562
563 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
564 soft_ref_policy()->should_clear_all_soft_refs();
565
566 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
567
568 const size_t metadata_prev_used = MetaspaceUtils::used_bytes();
569
570 print_heap_before_gc();
571
572 {
573 FlagSetting fl(_is_gc_active, true);
574
575 bool complete = full && (max_generation == OldGen);
576 bool old_collects_young = complete && !ScavengeBeforeFullGC;
577 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
578
579 FormatBuffer<> gc_string("%s", "Pause ");
580 if (do_young_collection) {
581 gc_string.append("Young");
582 } else {
583 gc_string.append("Full");
584 }
585
586 GCTraceCPUTime tcpu;
587 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
588
589 gc_prologue(complete);
590 increment_total_collections(complete);
591
592 size_t young_prev_used = _young_gen->used();
593 size_t old_prev_used = _old_gen->used();
594
595 bool run_verification = total_collections() >= VerifyGCStartAt;
596
597 bool prepared_for_verification = false;
598 bool collected_old = false;
599
600 if (do_young_collection) {
601 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
602 prepare_for_verify();
603 prepared_for_verification = true;
604 }
605
606 collect_generation(_young_gen,
607 full,
608 size,
609 is_tlab,
610 run_verification && VerifyGCLevel <= 0,
611 do_clear_all_soft_refs,
612 false);
613
614 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
615 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
616 // Allocation request was met by young GC.
617 size = 0;
618 }
619 }
620
621 bool must_restore_marks_for_biased_locking = false;
622
623 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
624 if (!complete) {
625 // The full_collections increment was missed above.
626 increment_total_full_collections();
627 }
628
629 if (!prepared_for_verification && run_verification &&
630 VerifyGCLevel <= 1 && VerifyBeforeGC) {
631 prepare_for_verify();
632 }
633
634 if (do_young_collection) {
635 // We did a young GC. Need a new GC id for the old GC.
636 GCIdMark gc_id_mark;
637 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
638 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
639 } else {
640 // No young GC done. Use the same GC id as was set up earlier in this method.
641 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
642 }
643
644 must_restore_marks_for_biased_locking = true;
645 collected_old = true;
646 }
647
648 // Update "complete" boolean wrt what actually transpired --
649 // for instance, a promotion failure could have led to
650 // a whole heap collection.
651 complete = complete || collected_old;
652
653 print_heap_change(young_prev_used, old_prev_used);
654 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
655
656 // Adjust generation sizes.
657 if (collected_old) {
658 _old_gen->compute_new_size();
659 }
660 _young_gen->compute_new_size();
661
662 if (complete) {
663 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
664 ClassLoaderDataGraph::purge();
665 MetaspaceUtils::verify_metrics();
666 // Resize the metaspace capacity after full collections
667 MetaspaceGC::compute_new_size();
668 update_full_collections_completed();
669 }
670
671 // Track memory usage and detect low memory after GC finishes
672 MemoryService::track_memory_usage();
673
674 gc_epilogue(complete);
675
676 if (must_restore_marks_for_biased_locking) {
677 BiasedLocking::restore_marks();
678 }
679 }
680
681 print_heap_after_gc();
682
683 #ifdef TRACESPINNING
684 ParallelTaskTerminator::print_termination_counts();
685 #endif
686 }
687
688 void GenCollectedHeap::register_nmethod(nmethod* nm) {
689 CodeCache::register_scavenge_root_nmethod(nm);
690 }
691
692 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
693 CodeCache::verify_scavenge_root_nmethod(nm);
694 }
695
696 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
697 GCCauseSetter x(this, GCCause::_allocation_failure);
698 HeapWord* result = NULL;
699
700 assert(size != 0, "Precondition violated");
701 if (GCLocker::is_active_and_needs_gc()) {
702 // GC locker is active; instead of a collection we will attempt
703 // to expand the heap, if there's room for expansion.
704 if (!is_maximal_no_gc()) {
705 result = expand_heap_and_allocate(size, is_tlab);
706 }
707 return result; // Could be null if we are out of space.
708 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
709 // Do an incremental collection.
710 do_collection(false, // full
711 false, // clear_all_soft_refs
712 size, // size
713 is_tlab, // is_tlab
714 GenCollectedHeap::OldGen); // max_generation
715 } else {
716 log_trace(gc)(" :: Trying full because partial may fail :: ");
717 // Try a full collection; see delta for bug id 6266275
718 // for the original code and why this has been simplified
719 // with from-space allocation criteria modified and
720 // such allocation moved out of the safepoint path.
721 do_collection(true, // full
722 false, // clear_all_soft_refs
723 size, // size
724 is_tlab, // is_tlab
725 GenCollectedHeap::OldGen); // max_generation
726 }
727
728 result = attempt_allocation(size, is_tlab, false /*first_only*/);
729
730 if (result != NULL) {
731 assert(is_in_reserved(result), "result not in heap");
732 return result;
733 }
734
735 // OK, collection failed, try expansion.
736 result = expand_heap_and_allocate(size, is_tlab);
737 if (result != NULL) {
738 return result;
739 }
740
741 // If we reach this point, we're really out of memory. Try every trick
742 // we can to reclaim memory. Force collection of soft references. Force
743 // a complete compaction of the heap. Any additional methods for finding
744 // free memory should be here, especially if they are expensive. If this
745 // attempt fails, an OOM exception will be thrown.
746 {
747 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
748
749 do_collection(true, // full
750 true, // clear_all_soft_refs
751 size, // size
752 is_tlab, // is_tlab
753 GenCollectedHeap::OldGen); // max_generation
754 }
755
756 result = attempt_allocation(size, is_tlab, false /* first_only */);
757 if (result != NULL) {
758 assert(is_in_reserved(result), "result not in heap");
759 return result;
760 }
761
762 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
763 "Flag should have been handled and cleared prior to this point");
764
765 // What else? We might try synchronous finalization later. If the total
766 // space available is large enough for the allocation, then a more
767 // complete compaction phase than we've tried so far might be
768 // appropriate.
769 return NULL;
770 }
771
772 #ifdef ASSERT
773 class AssertNonScavengableClosure: public OopClosure {
774 public:
775 virtual void do_oop(oop* p) {
776 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
777 "Referent should not be scavengable."); }
778 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
779 };
780 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
781 #endif
782
783 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
784 ScanningOption so,
785 OopClosure* strong_roots,
786 CLDClosure* strong_cld_closure,
787 CLDClosure* weak_cld_closure,
788 CodeBlobToOopClosure* code_roots) {
789 // General roots.
790 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
791 assert(code_roots != NULL, "code root closure should always be set");
792 // _n_termination for _process_strong_tasks should be set up stream
793 // in a method not running in a GC worker. Otherwise the GC worker
794 // could be trying to change the termination condition while the task
795 // is executing in another GC worker.
796
797 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
798 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
799 }
800
801 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
802 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
803
804 bool is_par = scope->n_threads() > 1;
805 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
806
807 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
808 Universe::oops_do(strong_roots);
809 }
810 // Global (strong) JNI handles
811 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
812 JNIHandles::oops_do(strong_roots);
813 }
814
815 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
816 ObjectSynchronizer::oops_do(strong_roots);
817 }
818 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
819 Management::oops_do(strong_roots);
820 }
821 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
822 JvmtiExport::oops_do(strong_roots);
823 }
824 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
825 AOTLoader::oops_do(strong_roots);
826 }
827
828 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
829 SystemDictionary::oops_do(strong_roots);
830 }
831
832 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
833 if (so & SO_ScavengeCodeCache) {
834 assert(code_roots != NULL, "must supply closure for code cache");
835
836 // We only visit parts of the CodeCache when scavenging.
837 CodeCache::scavenge_root_nmethods_do(code_roots);
838 }
839 if (so & SO_AllCodeCache) {
840 assert(code_roots != NULL, "must supply closure for code cache");
841
842 // CMSCollector uses this to do intermediate-strength collections.
843 // We scan the entire code cache, since CodeCache::do_unloading is not called.
844 CodeCache::blobs_do(code_roots);
845 }
846 // Verify that the code cache contents are not subject to
847 // movement by a scavenging collection.
848 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
849 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
850 }
851 }
852
853 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
854 OopClosure* root_closure) {
855 assert(root_closure != NULL, "Must be set");
856 // All threads execute the following. A specific chunk of buckets
857 // from the StringTable are the individual tasks.
858 if (scope->n_threads() > 1) {
859 StringTable::possibly_parallel_oops_do(root_closure);
860 } else {
861 StringTable::oops_do(root_closure);
862 }
863 }
864
865 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
866 OopsInGenClosure* root_closure,
867 OopsInGenClosure* old_gen_closure,
868 CLDClosure* cld_closure) {
869 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
870
871 process_roots(scope, SO_ScavengeCodeCache, root_closure,
872 cld_closure, cld_closure, &mark_code_closure);
873 process_string_table_roots(scope, root_closure);
874
875 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
876 root_closure->reset_generation();
877 }
878
879 // When collection is parallel, all threads get to cooperate to do
880 // old generation scanning.
881 old_gen_closure->set_generation(_old_gen);
882 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
883 old_gen_closure->reset_generation();
884
885 _process_strong_tasks->all_tasks_completed(scope->n_threads());
886 }
887
888 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
889 bool is_adjust_phase,
890 ScanningOption so,
891 bool only_strong_roots,
892 OopsInGenClosure* root_closure,
893 CLDClosure* cld_closure) {
894 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
895 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
896
897 process_roots(scope, so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure);
898 if (is_adjust_phase) {
899 // We never treat the string table as roots during marking
900 // for the full gc, so we only need to process it during
901 // the adjust phase.
902 process_string_table_roots(scope, root_closure);
903 }
904
905 _process_strong_tasks->all_tasks_completed(scope->n_threads());
906 }
907
908 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
909 WeakProcessor::oops_do(root_closure);
910 _young_gen->ref_processor()->weak_oops_do(root_closure);
911 _old_gen->ref_processor()->weak_oops_do(root_closure);
912 }
913
914 bool GenCollectedHeap::no_allocs_since_save_marks() {
915 return _young_gen->no_allocs_since_save_marks() &&
916 _old_gen->no_allocs_since_save_marks();
917 }
918
919 bool GenCollectedHeap::supports_inline_contig_alloc() const {
920 return _young_gen->supports_inline_contig_alloc();
921 }
922
923 HeapWord* volatile* GenCollectedHeap::top_addr() const {
924 return _young_gen->top_addr();
925 }
926
927 HeapWord** GenCollectedHeap::end_addr() const {
928 return _young_gen->end_addr();
929 }
930
931 // public collection interfaces
932
933 void GenCollectedHeap::collect(GCCause::Cause cause) {
934 if (cause == GCCause::_wb_young_gc) {
935 // Young collection for the WhiteBox API.
936 collect(cause, YoungGen);
937 } else {
938 #ifdef ASSERT
939 if (cause == GCCause::_scavenge_alot) {
940 // Young collection only.
941 collect(cause, YoungGen);
942 } else {
943 // Stop-the-world full collection.
944 collect(cause, OldGen);
945 }
946 #else
947 // Stop-the-world full collection.
948 collect(cause, OldGen);
949 #endif
950 }
951 }
952
953 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
954 // The caller doesn't have the Heap_lock
955 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
956 MutexLocker ml(Heap_lock);
957 collect_locked(cause, max_generation);
958 }
959
960 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
961 // The caller has the Heap_lock
962 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
963 collect_locked(cause, OldGen);
964 }
965
966 // this is the private collection interface
967 // The Heap_lock is expected to be held on entry.
968
969 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
970 // Read the GC count while holding the Heap_lock
971 unsigned int gc_count_before = total_collections();
972 unsigned int full_gc_count_before = total_full_collections();
973 {
974 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
975 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
976 cause, max_generation);
977 VMThread::execute(&op);
978 }
979 }
980
981 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
982 do_full_collection(clear_all_soft_refs, OldGen);
983 }
984
985 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
986 GenerationType last_generation) {
987 GenerationType local_last_generation;
988 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
989 gc_cause() == GCCause::_gc_locker) {
990 local_last_generation = YoungGen;
991 } else {
992 local_last_generation = last_generation;
993 }
994
995 do_collection(true, // full
996 clear_all_soft_refs, // clear_all_soft_refs
997 0, // size
998 false, // is_tlab
999 local_last_generation); // last_generation
1000 // Hack XXX FIX ME !!!
1001 // A scavenge may not have been attempted, or may have
1002 // been attempted and failed, because the old gen was too full
1003 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1004 incremental_collection_will_fail(false /* don't consult_young */)) {
1005 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1006 // This time allow the old gen to be collected as well
1007 do_collection(true, // full
1008 clear_all_soft_refs, // clear_all_soft_refs
1009 0, // size
1010 false, // is_tlab
1011 OldGen); // last_generation
1012 }
1013 }
1014
1015 bool GenCollectedHeap::is_in_young(oop p) {
1016 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1017 assert(result == _young_gen->is_in_reserved(p),
1018 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1019 return result;
1020 }
1021
1022 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1023 bool GenCollectedHeap::is_in(const void* p) const {
1024 return _young_gen->is_in(p) || _old_gen->is_in(p);
1025 }
1026
1027 #ifdef ASSERT
1028 // Don't implement this by using is_in_young(). This method is used
1029 // in some cases to check that is_in_young() is correct.
1030 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1031 assert(is_in_reserved(p) || p == NULL,
1032 "Does not work if address is non-null and outside of the heap");
1033 return p < _young_gen->reserved().end() && p != NULL;
1034 }
1035 #endif
1036
1037 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
1038 NoHeaderExtendedOopClosure no_header_cl(cl);
1039 oop_iterate(&no_header_cl);
1040 }
1041
1042 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
1043 _young_gen->oop_iterate(cl);
1044 _old_gen->oop_iterate(cl);
1045 }
1046
1047 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1048 _young_gen->object_iterate(cl);
1049 _old_gen->object_iterate(cl);
1050 }
1051
1052 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1053 _young_gen->safe_object_iterate(cl);
1054 _old_gen->safe_object_iterate(cl);
1055 }
1056
1057 Space* GenCollectedHeap::space_containing(const void* addr) const {
1058 Space* res = _young_gen->space_containing(addr);
1059 if (res != NULL) {
1060 return res;
1061 }
1062 res = _old_gen->space_containing(addr);
1063 assert(res != NULL, "Could not find containing space");
1064 return res;
1065 }
1066
1067 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1068 assert(is_in_reserved(addr), "block_start of address outside of heap");
1069 if (_young_gen->is_in_reserved(addr)) {
1070 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1071 return _young_gen->block_start(addr);
1072 }
1073
1074 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1075 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1076 return _old_gen->block_start(addr);
1077 }
1078
1079 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1080 assert(is_in_reserved(addr), "block_size of address outside of heap");
1081 if (_young_gen->is_in_reserved(addr)) {
1082 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1083 return _young_gen->block_size(addr);
1084 }
1085
1086 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1087 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1088 return _old_gen->block_size(addr);
1089 }
1090
1091 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1092 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1093 assert(block_start(addr) == addr, "addr must be a block start");
1094 if (_young_gen->is_in_reserved(addr)) {
1095 return _young_gen->block_is_obj(addr);
1096 }
1097
1098 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1099 return _old_gen->block_is_obj(addr);
1100 }
1101
1102 bool GenCollectedHeap::supports_tlab_allocation() const {
1103 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1104 return _young_gen->supports_tlab_allocation();
1105 }
1106
1107 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1108 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1109 if (_young_gen->supports_tlab_allocation()) {
1110 return _young_gen->tlab_capacity();
1111 }
1112 return 0;
1113 }
1114
1115 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1116 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1117 if (_young_gen->supports_tlab_allocation()) {
1118 return _young_gen->tlab_used();
1119 }
1120 return 0;
1121 }
1122
1123 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1124 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1125 if (_young_gen->supports_tlab_allocation()) {
1126 return _young_gen->unsafe_max_tlab_alloc();
1127 }
1128 return 0;
1129 }
1130
1131 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1132 size_t requested_size,
1133 size_t* actual_size) {
1134 bool gc_overhead_limit_was_exceeded;
1135 HeapWord* result = mem_allocate_work(requested_size /* size */,
1136 true /* is_tlab */,
1137 &gc_overhead_limit_was_exceeded);
1138 if (result != NULL) {
1139 *actual_size = requested_size;
1140 }
1141
1142 return result;
1143 }
1144
1145 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1146 // from the list headed by "*prev_ptr".
1147 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1148 bool first = true;
1149 size_t min_size = 0; // "first" makes this conceptually infinite.
1150 ScratchBlock **smallest_ptr, *smallest;
1151 ScratchBlock *cur = *prev_ptr;
1152 while (cur) {
1153 assert(*prev_ptr == cur, "just checking");
1154 if (first || cur->num_words < min_size) {
1155 smallest_ptr = prev_ptr;
1156 smallest = cur;
1157 min_size = smallest->num_words;
1158 first = false;
1159 }
1160 prev_ptr = &cur->next;
1161 cur = cur->next;
1162 }
1163 smallest = *smallest_ptr;
1164 *smallest_ptr = smallest->next;
1165 return smallest;
1166 }
1167
1168 // Sort the scratch block list headed by res into decreasing size order,
1169 // and set "res" to the result.
1170 static void sort_scratch_list(ScratchBlock*& list) {
1171 ScratchBlock* sorted = NULL;
1172 ScratchBlock* unsorted = list;
1173 while (unsorted) {
1174 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1175 smallest->next = sorted;
1176 sorted = smallest;
1177 }
1178 list = sorted;
1179 }
1180
1181 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1182 size_t max_alloc_words) {
1183 ScratchBlock* res = NULL;
1184 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1185 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1186 sort_scratch_list(res);
1187 return res;
1188 }
1189
1190 void GenCollectedHeap::release_scratch() {
1191 _young_gen->reset_scratch();
1192 _old_gen->reset_scratch();
1193 }
1194
1195 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1196 void do_generation(Generation* gen) {
1197 gen->prepare_for_verify();
1198 }
1199 };
1200
1201 void GenCollectedHeap::prepare_for_verify() {
1202 ensure_parsability(false); // no need to retire TLABs
1203 GenPrepareForVerifyClosure blk;
1204 generation_iterate(&blk, false);
1205 }
1206
1207 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1208 bool old_to_young) {
1209 if (old_to_young) {
1210 cl->do_generation(_old_gen);
1211 cl->do_generation(_young_gen);
1212 } else {
1213 cl->do_generation(_young_gen);
1214 cl->do_generation(_old_gen);
1215 }
1216 }
1217
1218 bool GenCollectedHeap::is_maximal_no_gc() const {
1219 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1220 }
1221
1222 void GenCollectedHeap::save_marks() {
1223 _young_gen->save_marks();
1224 _old_gen->save_marks();
1225 }
1226
1227 GenCollectedHeap* GenCollectedHeap::heap() {
1228 CollectedHeap* heap = Universe::heap();
1229 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1230 assert(heap->kind() == CollectedHeap::Serial ||
1231 heap->kind() == CollectedHeap::CMS, "Invalid name");
1232 return (GenCollectedHeap*) heap;
1233 }
1234
1235 #if INCLUDE_SERIALGC
1236 void GenCollectedHeap::prepare_for_compaction() {
1237 // Start by compacting into same gen.
1238 CompactPoint cp(_old_gen);
1239 _old_gen->prepare_for_compaction(&cp);
1240 _young_gen->prepare_for_compaction(&cp);
1241 }
1242 #endif // INCLUDE_SERIALGC
1243
1244 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1245 log_debug(gc, verify)("%s", _old_gen->name());
1246 _old_gen->verify();
1247
1248 log_debug(gc, verify)("%s", _old_gen->name());
1249 _young_gen->verify();
1250
1251 log_debug(gc, verify)("RemSet");
1252 rem_set()->verify();
1253 }
1254
1255 void GenCollectedHeap::print_on(outputStream* st) const {
1256 _young_gen->print_on(st);
1257 _old_gen->print_on(st);
1258 MetaspaceUtils::print_on(st);
1259 }
1260
1261 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1262 }
1263
1264 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1265 }
1266
1267 void GenCollectedHeap::print_tracing_info() const {
1268 if (log_is_enabled(Debug, gc, heap, exit)) {
1269 LogStreamHandle(Debug, gc, heap, exit) lsh;
1270 _young_gen->print_summary_info_on(&lsh);
1271 _old_gen->print_summary_info_on(&lsh);
1272 }
1273 }
1274
1275 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1276 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1277 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1278 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1279 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1280 }
1281
1282 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1283 private:
1284 bool _full;
1285 public:
1286 void do_generation(Generation* gen) {
1287 gen->gc_prologue(_full);
1288 }
1289 GenGCPrologueClosure(bool full) : _full(full) {};
1290 };
1291
1292 void GenCollectedHeap::gc_prologue(bool full) {
1293 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1294
1295 // Fill TLAB's and such
1296 CollectedHeap::accumulate_statistics_all_tlabs();
1297 ensure_parsability(true); // retire TLABs
1298
1299 // Walk generations
1300 GenGCPrologueClosure blk(full);
1301 generation_iterate(&blk, false); // not old-to-young.
1302 };
1303
1304 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1305 private:
1306 bool _full;
1307 public:
1308 void do_generation(Generation* gen) {
1309 gen->gc_epilogue(_full);
1310 }
1311 GenGCEpilogueClosure(bool full) : _full(full) {};
1312 };
1313
1314 void GenCollectedHeap::gc_epilogue(bool full) {
1315 #if COMPILER2_OR_JVMCI
1316 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1317 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1318 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1319 #endif // COMPILER2_OR_JVMCI
1320
1321 resize_all_tlabs();
1322
1323 GenGCEpilogueClosure blk(full);
1324 generation_iterate(&blk, false); // not old-to-young.
1325
1326 if (!CleanChunkPoolAsync) {
1327 Chunk::clean_chunk_pool();
1328 }
1329
1330 MetaspaceCounters::update_performance_counters();
1331 CompressedClassSpaceCounters::update_performance_counters();
1332 };
1333
1334 #ifndef PRODUCT
1335 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1336 private:
1337 public:
1338 void do_generation(Generation* gen) {
1339 gen->record_spaces_top();
1340 }
1341 };
1342
1343 void GenCollectedHeap::record_gen_tops_before_GC() {
1344 if (ZapUnusedHeapArea) {
1345 GenGCSaveTopsBeforeGCClosure blk;
1346 generation_iterate(&blk, false); // not old-to-young.
1347 }
1348 }
1349 #endif // not PRODUCT
1350
1351 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1352 public:
1353 void do_generation(Generation* gen) {
1354 gen->ensure_parsability();
1355 }
1356 };
1357
1358 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1359 CollectedHeap::ensure_parsability(retire_tlabs);
1360 GenEnsureParsabilityClosure ep_cl;
1361 generation_iterate(&ep_cl, false);
1362 }
1363
1364 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1365 oop obj,
1366 size_t obj_size) {
1367 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1368 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1369 HeapWord* result = NULL;
1370
1371 result = old_gen->expand_and_allocate(obj_size, false);
1372
1373 if (result != NULL) {
1374 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1375 }
1376 return oop(result);
1377 }
1378
1379 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1380 jlong _time; // in ms
1381 jlong _now; // in ms
1382
1383 public:
1384 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1385
1386 jlong time() { return _time; }
1387
1388 void do_generation(Generation* gen) {
1389 _time = MIN2(_time, gen->time_of_last_gc(_now));
1390 }
1391 };
1392
1393 jlong GenCollectedHeap::millis_since_last_gc() {
1394 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1395 // provided the underlying platform provides such a time source
1396 // (and it is bug free). So we still have to guard against getting
1397 // back a time later than 'now'.
1398 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1399 GenTimeOfLastGCClosure tolgc_cl(now);
1400 // iterate over generations getting the oldest
1401 // time that a generation was collected
1402 generation_iterate(&tolgc_cl, false);
1403
1404 jlong retVal = now - tolgc_cl.time();
1405 if (retVal < 0) {
1406 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1407 ". returning zero instead.", retVal);
1408 return 0;
1409 }
1410 return retVal;
1411 }