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/shared/adaptiveSizePolicy.hpp"
34 #include "gc/shared/cardTableBarrierSet.hpp"
35 #include "gc/shared/cardTableRS.hpp"
36 #include "gc/shared/collectedHeap.inline.hpp"
37 #include "gc/shared/collectorCounters.hpp"
38 #include "gc/shared/gcId.hpp"
39 #include "gc/shared/gcLocker.hpp"
40 #include "gc/shared/gcPolicyCounters.hpp"
41 #include "gc/shared/gcTrace.hpp"
42 #include "gc/shared/gcTraceTime.inline.hpp"
43 #include "gc/shared/genCollectedHeap.hpp"
44 #include "gc/shared/genOopClosures.inline.hpp"
45 #include "gc/shared/generationSpec.hpp"
46 #include "gc/shared/space.hpp"
47 #include "gc/shared/strongRootsScope.hpp"
48 #include "gc/shared/vmGCOperations.hpp"
49 #include "gc/shared/weakProcessor.hpp"
50 #include "gc/shared/workgroup.hpp"
51 #include "memory/filemap.hpp"
52 #include "memory/metaspaceCounters.hpp"
53 #include "memory/resourceArea.hpp"
54 #include "oops/oop.inline.hpp"
55 #include "runtime/biasedLocking.hpp"
56 #include "runtime/flags/flagSetting.hpp"
57 #include "runtime/handles.hpp"
58 #include "runtime/handles.inline.hpp"
59 #include "runtime/java.hpp"
60 #include "runtime/vmThread.hpp"
61 #include "services/management.hpp"
62 #include "services/memoryService.hpp"
63 #include "utilities/debug.hpp"
64 #include "utilities/formatBuffer.hpp"
65 #include "utilities/macros.hpp"
66 #include "utilities/stack.inline.hpp"
67 #include "utilities/vmError.hpp"
68
69 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy,
70 Generation::Name young,
71 Generation::Name old,
72 const char* policy_counters_name) :
73 CollectedHeap(),
74 _rem_set(NULL),
75 _young_gen_spec(new GenerationSpec(young,
76 policy->initial_young_size(),
77 policy->max_young_size(),
78 policy->gen_alignment())),
79 _old_gen_spec(new GenerationSpec(old,
80 policy->initial_old_size(),
81 policy->max_old_size(),
82 policy->gen_alignment())),
83 _gen_policy(policy),
84 _soft_ref_gen_policy(),
85 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
86 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
87 _full_collections_completed(0) {
88 }
89
90 jint GenCollectedHeap::initialize() {
91 // While there are no constraints in the GC code that HeapWordSize
92 // be any particular value, there are multiple other areas in the
93 // system which believe this to be true (e.g. oop->object_size in some
94 // cases incorrectly returns the size in wordSize units rather than
95 // HeapWordSize).
96 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
97
98 // Allocate space for the heap.
99
100 char* heap_address;
101 ReservedSpace heap_rs;
102
103 size_t heap_alignment = collector_policy()->heap_alignment();
104
105 heap_address = allocate(heap_alignment, &heap_rs);
106
107 if (!heap_rs.is_reserved()) {
108 vm_shutdown_during_initialization(
109 "Could not reserve enough space for object heap");
110 return JNI_ENOMEM;
111 }
112
113 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
114
115 _rem_set = create_rem_set(reserved_region());
116 _rem_set->initialize();
117 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
118 bs->initialize();
119 BarrierSet::set_barrier_set(bs);
120
121 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false);
122 _young_gen = _young_gen_spec->init(young_rs, rem_set());
123 heap_rs = heap_rs.last_part(_young_gen_spec->max_size());
124
125 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false);
126 _old_gen = _old_gen_spec->init(old_rs, rem_set());
127 clear_incremental_collection_failed();
128
129 return JNI_OK;
130 }
131
132 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
133 return new CardTableRS(reserved_region, false /* scan_concurrently */);
134 }
135
136 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
137 size_t init_promo_size,
138 size_t init_survivor_size) {
139 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
140 _size_policy = new AdaptiveSizePolicy(init_eden_size,
141 init_promo_size,
142 init_survivor_size,
143 max_gc_pause_sec,
144 GCTimeRatio);
145 }
146
147 char* GenCollectedHeap::allocate(size_t alignment,
148 ReservedSpace* heap_rs){
149 // Now figure out the total size.
150 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
151 assert(alignment % pageSize == 0, "Must be");
152
153 // Check for overflow.
154 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
155 if (total_reserved < _young_gen_spec->max_size()) {
156 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
157 "the maximum representable size");
158 }
159 assert(total_reserved % alignment == 0,
160 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
161 SIZE_FORMAT, total_reserved, alignment);
162
163 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
164
165 os::trace_page_sizes("Heap",
166 collector_policy()->min_heap_byte_size(),
167 total_reserved,
168 alignment,
169 heap_rs->base(),
170 heap_rs->size());
171
172 return heap_rs->base();
173 }
174
175 void GenCollectedHeap::post_initialize() {
176 CollectedHeap::post_initialize();
177 ref_processing_init();
178 check_gen_kinds();
179 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
180
181 initialize_size_policy(def_new_gen->eden()->capacity(),
182 _old_gen->capacity(),
183 def_new_gen->from()->capacity());
184 }
185
186 void GenCollectedHeap::ref_processing_init() {
187 _young_gen->ref_processor_init();
188 _old_gen->ref_processor_init();
189 }
190
191 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
192 return _young_gen_spec;
193 }
194
195 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
196 return _old_gen_spec;
197 }
198
199 size_t GenCollectedHeap::capacity() const {
200 return _young_gen->capacity() + _old_gen->capacity();
201 }
202
203 size_t GenCollectedHeap::used() const {
204 return _young_gen->used() + _old_gen->used();
205 }
206
207 void GenCollectedHeap::save_used_regions() {
208 _old_gen->save_used_region();
209 _young_gen->save_used_region();
210 }
211
212 size_t GenCollectedHeap::max_capacity() const {
213 return _young_gen->max_capacity() + _old_gen->max_capacity();
214 }
215
216 // Update the _full_collections_completed counter
217 // at the end of a stop-world full GC.
218 unsigned int GenCollectedHeap::update_full_collections_completed() {
219 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
220 assert(_full_collections_completed <= _total_full_collections,
221 "Can't complete more collections than were started");
222 _full_collections_completed = _total_full_collections;
223 ml.notify_all();
224 return _full_collections_completed;
225 }
226
227 // Update the _full_collections_completed counter, as appropriate,
228 // at the end of a concurrent GC cycle. Note the conditional update
229 // below to allow this method to be called by a concurrent collector
230 // without synchronizing in any manner with the VM thread (which
231 // may already have initiated a STW full collection "concurrently").
232 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
233 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
234 assert((_full_collections_completed <= _total_full_collections) &&
235 (count <= _total_full_collections),
236 "Can't complete more collections than were started");
237 if (count > _full_collections_completed) {
238 _full_collections_completed = count;
239 ml.notify_all();
240 }
241 return _full_collections_completed;
242 }
243
244 // Return true if any of the following is true:
245 // . the allocation won't fit into the current young gen heap
246 // . gc locker is occupied (jni critical section)
247 // . heap memory is tight -- the most recent previous collection
248 // was a full collection because a partial collection (would
249 // have) failed and is likely to fail again
250 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
251 size_t young_capacity = young_gen()->capacity_before_gc();
252 return (word_size > heap_word_size(young_capacity))
253 || GCLocker::is_active_and_needs_gc()
254 || incremental_collection_failed();
255 }
256
257 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
258 HeapWord* result = NULL;
259 if (old_gen()->should_allocate(size, is_tlab)) {
260 result = old_gen()->expand_and_allocate(size, is_tlab);
261 }
262 if (result == NULL) {
263 if (young_gen()->should_allocate(size, is_tlab)) {
264 result = young_gen()->expand_and_allocate(size, is_tlab);
265 }
266 }
267 assert(result == NULL || is_in_reserved(result), "result not in heap");
268 return result;
269 }
270
271 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
272 bool is_tlab,
273 bool* gc_overhead_limit_was_exceeded) {
274 debug_only(check_for_valid_allocation_state());
275 assert(no_gc_in_progress(), "Allocation during gc not allowed");
276
277 // In general gc_overhead_limit_was_exceeded should be false so
278 // set it so here and reset it to true only if the gc time
279 // limit is being exceeded as checked below.
280 *gc_overhead_limit_was_exceeded = false;
281
282 HeapWord* result = NULL;
283
284 // Loop until the allocation is satisfied, or unsatisfied after GC.
285 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
286 HandleMark hm; // Discard any handles allocated in each iteration.
287
288 // First allocation attempt is lock-free.
289 Generation *young = young_gen();
290 assert(young->supports_inline_contig_alloc(),
291 "Otherwise, must do alloc within heap lock");
292 if (young->should_allocate(size, is_tlab)) {
293 result = young->par_allocate(size, is_tlab);
294 if (result != NULL) {
295 assert(is_in_reserved(result), "result not in heap");
296 return result;
297 }
298 }
299 uint gc_count_before; // Read inside the Heap_lock locked region.
300 {
301 MutexLocker ml(Heap_lock);
302 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
303 // Note that only large objects get a shot at being
304 // allocated in later generations.
305 bool first_only = !should_try_older_generation_allocation(size);
306
307 result = attempt_allocation(size, is_tlab, first_only);
308 if (result != NULL) {
309 assert(is_in_reserved(result), "result not in heap");
310 return result;
311 }
312
313 if (GCLocker::is_active_and_needs_gc()) {
314 if (is_tlab) {
315 return NULL; // Caller will retry allocating individual object.
316 }
317 if (!is_maximal_no_gc()) {
318 // Try and expand heap to satisfy request.
319 result = expand_heap_and_allocate(size, is_tlab);
320 // Result could be null if we are out of space.
321 if (result != NULL) {
322 return result;
323 }
324 }
325
326 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
327 return NULL; // We didn't get to do a GC and we didn't get any memory.
328 }
329
330 // If this thread is not in a jni critical section, we stall
331 // the requestor until the critical section has cleared and
332 // GC allowed. When the critical section clears, a GC is
333 // initiated by the last thread exiting the critical section; so
334 // we retry the allocation sequence from the beginning of the loop,
335 // rather than causing more, now probably unnecessary, GC attempts.
336 JavaThread* jthr = JavaThread::current();
337 if (!jthr->in_critical()) {
338 MutexUnlocker mul(Heap_lock);
339 // Wait for JNI critical section to be exited
340 GCLocker::stall_until_clear();
341 gclocker_stalled_count += 1;
342 continue;
343 } else {
344 if (CheckJNICalls) {
345 fatal("Possible deadlock due to allocating while"
346 " in jni critical section");
347 }
348 return NULL;
349 }
350 }
351
352 // Read the gc count while the heap lock is held.
353 gc_count_before = total_collections();
354 }
355
356 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
357 VMThread::execute(&op);
358 if (op.prologue_succeeded()) {
359 result = op.result();
360 if (op.gc_locked()) {
361 assert(result == NULL, "must be NULL if gc_locked() is true");
362 continue; // Retry and/or stall as necessary.
363 }
364
365 // Allocation has failed and a collection
366 // has been done. If the gc time limit was exceeded the
367 // this time, return NULL so that an out-of-memory
368 // will be thrown. Clear gc_overhead_limit_exceeded
369 // so that the overhead exceeded does not persist.
370
371 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
372 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
373
374 if (limit_exceeded && softrefs_clear) {
375 *gc_overhead_limit_was_exceeded = true;
376 size_policy()->set_gc_overhead_limit_exceeded(false);
377 if (op.result() != NULL) {
378 CollectedHeap::fill_with_object(op.result(), size);
379 }
380 return NULL;
381 }
382 assert(result == NULL || is_in_reserved(result),
383 "result not in heap");
384 return result;
385 }
386
387 // Give a warning if we seem to be looping forever.
388 if ((QueuedAllocationWarningCount > 0) &&
389 (try_count % QueuedAllocationWarningCount == 0)) {
390 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
391 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
392 }
393 }
394 }
395
396 #ifndef PRODUCT
397 // Override of memory state checking method in CollectedHeap:
398 // Some collectors (CMS for example) can't have badHeapWordVal written
399 // in the first two words of an object. (For instance , in the case of
400 // CMS these words hold state used to synchronize between certain
401 // (concurrent) GC steps and direct allocating mutators.)
402 // The skip_header_HeapWords() method below, allows us to skip
403 // over the requisite number of HeapWord's. Note that (for
404 // generational collectors) this means that those many words are
405 // skipped in each object, irrespective of the generation in which
406 // that object lives. The resultant loss of precision seems to be
407 // harmless and the pain of avoiding that imprecision appears somewhat
408 // higher than we are prepared to pay for such rudimentary debugging
409 // support.
410 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
411 size_t size) {
412 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
413 // We are asked to check a size in HeapWords,
414 // but the memory is mangled in juint words.
415 juint* start = (juint*) (addr + skip_header_HeapWords());
416 juint* end = (juint*) (addr + size);
417 for (juint* slot = start; slot < end; slot += 1) {
418 assert(*slot == badHeapWordVal,
419 "Found non badHeapWordValue in pre-allocation check");
420 }
421 }
422 }
423 #endif
424
425 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
426 bool is_tlab,
427 bool first_only) {
428 HeapWord* res = NULL;
429
430 if (_young_gen->should_allocate(size, is_tlab)) {
431 res = _young_gen->allocate(size, is_tlab);
432 if (res != NULL || first_only) {
433 return res;
434 }
435 }
436
437 if (_old_gen->should_allocate(size, is_tlab)) {
438 res = _old_gen->allocate(size, is_tlab);
439 }
440
441 return res;
442 }
443
444 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
445 bool* gc_overhead_limit_was_exceeded) {
446 return mem_allocate_work(size,
447 false /* is_tlab */,
448 gc_overhead_limit_was_exceeded);
449 }
450
451 bool GenCollectedHeap::must_clear_all_soft_refs() {
452 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
453 _gc_cause == GCCause::_wb_full_gc;
454 }
455
456 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
457 bool is_tlab, bool run_verification, bool clear_soft_refs,
458 bool restore_marks_for_biased_locking) {
459 FormatBuffer<> title("Collect gen: %s", gen->short_name());
460 GCTraceTime(Trace, gc, phases) t1(title);
461 TraceCollectorStats tcs(gen->counters());
462 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
463
464 gen->stat_record()->invocations++;
465 gen->stat_record()->accumulated_time.start();
466
467 // Must be done anew before each collection because
468 // a previous collection will do mangling and will
469 // change top of some spaces.
470 record_gen_tops_before_GC();
471
472 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
473
474 if (run_verification && VerifyBeforeGC) {
475 HandleMark hm; // Discard invalid handles created during verification
476 Universe::verify("Before GC");
477 }
478 COMPILER2_PRESENT(DerivedPointerTable::clear());
479
480 if (restore_marks_for_biased_locking) {
481 // We perform this mark word preservation work lazily
482 // because it's only at this point that we know whether we
483 // absolutely have to do it; we want to avoid doing it for
484 // scavenge-only collections where it's unnecessary
485 BiasedLocking::preserve_marks();
486 }
487
488 // Do collection work
489 {
490 // Note on ref discovery: For what appear to be historical reasons,
491 // GCH enables and disabled (by enqueing) refs discovery.
492 // In the future this should be moved into the generation's
493 // collect method so that ref discovery and enqueueing concerns
494 // are local to a generation. The collect method could return
495 // an appropriate indication in the case that notification on
496 // the ref lock was needed. This will make the treatment of
497 // weak refs more uniform (and indeed remove such concerns
498 // from GCH). XXX
499
500 HandleMark hm; // Discard invalid handles created during gc
501 save_marks(); // save marks for all gens
502 // We want to discover references, but not process them yet.
503 // This mode is disabled in process_discovered_references if the
504 // generation does some collection work, or in
505 // enqueue_discovered_references if the generation returns
506 // without doing any work.
507 ReferenceProcessor* rp = gen->ref_processor();
508 // If the discovery of ("weak") refs in this generation is
509 // atomic wrt other collectors in this configuration, we
510 // are guaranteed to have empty discovered ref lists.
511 if (rp->discovery_is_atomic()) {
512 rp->enable_discovery();
513 rp->setup_policy(clear_soft_refs);
514 } else {
515 // collect() below will enable discovery as appropriate
516 }
517 gen->collect(full, clear_soft_refs, size, is_tlab);
518 if (!rp->enqueuing_is_done()) {
519 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q());
520 rp->enqueue_discovered_references(NULL, &pt);
521 pt.print_enqueue_phase();
522 } else {
523 rp->set_enqueuing_is_done(false);
524 }
525 rp->verify_no_references_recorded();
526 }
527
528 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
529
530 gen->stat_record()->accumulated_time.stop();
531
532 update_gc_stats(gen, full);
533
534 if (run_verification && VerifyAfterGC) {
535 HandleMark hm; // Discard invalid handles created during verification
536 Universe::verify("After GC");
537 }
538 }
539
540 void GenCollectedHeap::do_collection(bool full,
541 bool clear_all_soft_refs,
542 size_t size,
543 bool is_tlab,
544 GenerationType max_generation) {
545 ResourceMark rm;
546 DEBUG_ONLY(Thread* my_thread = Thread::current();)
547
548 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
549 assert(my_thread->is_VM_thread() ||
550 my_thread->is_ConcurrentGC_thread(),
551 "incorrect thread type capability");
552 assert(Heap_lock->is_locked(),
553 "the requesting thread should have the Heap_lock");
554 guarantee(!is_gc_active(), "collection is not reentrant");
555
556 if (GCLocker::check_active_before_gc()) {
557 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
558 }
559
560 GCIdMark gc_id_mark;
561
562 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
563 soft_ref_policy()->should_clear_all_soft_refs();
564
565 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
566
567 const size_t metadata_prev_used = MetaspaceUtils::used_bytes();
568
569 print_heap_before_gc();
570
571 {
572 FlagSetting fl(_is_gc_active, true);
573
574 bool complete = full && (max_generation == OldGen);
575 bool old_collects_young = complete && !ScavengeBeforeFullGC;
576 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
577
578 FormatBuffer<> gc_string("%s", "Pause ");
579 if (do_young_collection) {
580 gc_string.append("Young");
581 } else {
582 gc_string.append("Full");
583 }
584
585 GCTraceCPUTime tcpu;
586 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
587
588 gc_prologue(complete);
589 increment_total_collections(complete);
590
591 size_t young_prev_used = _young_gen->used();
592 size_t old_prev_used = _old_gen->used();
593
594 bool run_verification = total_collections() >= VerifyGCStartAt;
595
596 bool prepared_for_verification = false;
597 bool collected_old = false;
598
599 if (do_young_collection) {
600 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
601 prepare_for_verify();
602 prepared_for_verification = true;
603 }
604
605 collect_generation(_young_gen,
606 full,
607 size,
608 is_tlab,
609 run_verification && VerifyGCLevel <= 0,
610 do_clear_all_soft_refs,
611 false);
612
613 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
614 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
615 // Allocation request was met by young GC.
616 size = 0;
617 }
618 }
619
620 bool must_restore_marks_for_biased_locking = false;
621
622 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
623 if (!complete) {
624 // The full_collections increment was missed above.
625 increment_total_full_collections();
626 }
627
628 if (!prepared_for_verification && run_verification &&
629 VerifyGCLevel <= 1 && VerifyBeforeGC) {
630 prepare_for_verify();
631 }
632
633 if (do_young_collection) {
634 // We did a young GC. Need a new GC id for the old GC.
635 GCIdMark gc_id_mark;
636 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
637 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
638 } else {
639 // No young GC done. Use the same GC id as was set up earlier in this method.
640 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
641 }
642
643 must_restore_marks_for_biased_locking = true;
644 collected_old = true;
645 }
646
647 // Update "complete" boolean wrt what actually transpired --
648 // for instance, a promotion failure could have led to
649 // a whole heap collection.
650 complete = complete || collected_old;
651
652 print_heap_change(young_prev_used, old_prev_used);
653 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
654
655 // Adjust generation sizes.
656 if (collected_old) {
657 _old_gen->compute_new_size();
658 }
659 _young_gen->compute_new_size();
660
661 if (complete) {
662 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
663 ClassLoaderDataGraph::purge();
664 MetaspaceUtils::verify_metrics();
665 // Resize the metaspace capacity after full collections
666 MetaspaceGC::compute_new_size();
667 update_full_collections_completed();
668 }
669
670 // Track memory usage and detect low memory after GC finishes
671 MemoryService::track_memory_usage();
672
673 gc_epilogue(complete);
674
675 if (must_restore_marks_for_biased_locking) {
676 BiasedLocking::restore_marks();
677 }
678 }
679
680 print_heap_after_gc();
681
682 #ifdef TRACESPINNING
683 ParallelTaskTerminator::print_termination_counts();
684 #endif
685 }
686
687 void GenCollectedHeap::register_nmethod(nmethod* nm) {
688 CodeCache::register_scavenge_root_nmethod(nm);
689 }
690
691 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
692 CodeCache::verify_scavenge_root_nmethod(nm);
693 }
694
695 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
696 GCCauseSetter x(this, GCCause::_allocation_failure);
697 HeapWord* result = NULL;
698
699 assert(size != 0, "Precondition violated");
700 if (GCLocker::is_active_and_needs_gc()) {
701 // GC locker is active; instead of a collection we will attempt
702 // to expand the heap, if there's room for expansion.
703 if (!is_maximal_no_gc()) {
704 result = expand_heap_and_allocate(size, is_tlab);
705 }
706 return result; // Could be null if we are out of space.
707 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
708 // Do an incremental collection.
709 do_collection(false, // full
710 false, // clear_all_soft_refs
711 size, // size
712 is_tlab, // is_tlab
713 GenCollectedHeap::OldGen); // max_generation
714 } else {
715 log_trace(gc)(" :: Trying full because partial may fail :: ");
716 // Try a full collection; see delta for bug id 6266275
717 // for the original code and why this has been simplified
718 // with from-space allocation criteria modified and
719 // such allocation moved out of the safepoint path.
720 do_collection(true, // full
721 false, // clear_all_soft_refs
722 size, // size
723 is_tlab, // is_tlab
724 GenCollectedHeap::OldGen); // max_generation
725 }
726
727 result = attempt_allocation(size, is_tlab, false /*first_only*/);
728
729 if (result != NULL) {
730 assert(is_in_reserved(result), "result not in heap");
731 return result;
732 }
733
734 // OK, collection failed, try expansion.
735 result = expand_heap_and_allocate(size, is_tlab);
736 if (result != NULL) {
737 return result;
738 }
739
740 // If we reach this point, we're really out of memory. Try every trick
741 // we can to reclaim memory. Force collection of soft references. Force
742 // a complete compaction of the heap. Any additional methods for finding
743 // free memory should be here, especially if they are expensive. If this
744 // attempt fails, an OOM exception will be thrown.
745 {
746 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
747
748 do_collection(true, // full
749 true, // clear_all_soft_refs
750 size, // size
751 is_tlab, // is_tlab
752 GenCollectedHeap::OldGen); // max_generation
753 }
754
755 result = attempt_allocation(size, is_tlab, false /* first_only */);
756 if (result != NULL) {
757 assert(is_in_reserved(result), "result not in heap");
758 return result;
759 }
760
761 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
762 "Flag should have been handled and cleared prior to this point");
763
764 // What else? We might try synchronous finalization later. If the total
765 // space available is large enough for the allocation, then a more
766 // complete compaction phase than we've tried so far might be
767 // appropriate.
768 return NULL;
769 }
770
771 #ifdef ASSERT
772 class AssertNonScavengableClosure: public OopClosure {
773 public:
774 virtual void do_oop(oop* p) {
775 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
776 "Referent should not be scavengable."); }
777 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
778 };
779 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
780 #endif
781
782 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
783 ScanningOption so,
784 OopClosure* strong_roots,
785 OopClosure* weak_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::roots_oops_do(strong_roots, weak_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, 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 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
896 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
897
898 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
899 if (is_adjust_phase) {
900 // We never treat the string table as roots during marking
901 // for the full gc, so we only need to process it during
902 // the adjust phase.
903 process_string_table_roots(scope, root_closure);
904 }
905
906 _process_strong_tasks->all_tasks_completed(scope->n_threads());
907 }
908
909 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
910 WeakProcessor::oops_do(root_closure);
911 _young_gen->ref_processor()->weak_oops_do(root_closure);
912 _old_gen->ref_processor()->weak_oops_do(root_closure);
913 }
914
915 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
916 void GenCollectedHeap:: \
917 oop_since_save_marks_iterate(GenerationType gen, \
918 OopClosureType* cur, \
919 OopClosureType* older) { \
920 if (gen == YoungGen) { \
921 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
922 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
923 } else { \
924 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
925 } \
926 }
927
928 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
929
930 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
931
932 bool GenCollectedHeap::no_allocs_since_save_marks() {
933 return _young_gen->no_allocs_since_save_marks() &&
934 _old_gen->no_allocs_since_save_marks();
935 }
936
937 bool GenCollectedHeap::supports_inline_contig_alloc() const {
938 return _young_gen->supports_inline_contig_alloc();
939 }
940
941 HeapWord* volatile* GenCollectedHeap::top_addr() const {
942 return _young_gen->top_addr();
943 }
944
945 HeapWord** GenCollectedHeap::end_addr() const {
946 return _young_gen->end_addr();
947 }
948
949 // public collection interfaces
950
951 void GenCollectedHeap::collect(GCCause::Cause cause) {
952 if (cause == GCCause::_wb_young_gc) {
953 // Young collection for the WhiteBox API.
954 collect(cause, YoungGen);
955 } else {
956 #ifdef ASSERT
957 if (cause == GCCause::_scavenge_alot) {
958 // Young collection only.
959 collect(cause, YoungGen);
960 } else {
961 // Stop-the-world full collection.
962 collect(cause, OldGen);
963 }
964 #else
965 // Stop-the-world full collection.
966 collect(cause, OldGen);
967 #endif
968 }
969 }
970
971 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
972 // The caller doesn't have the Heap_lock
973 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
974 MutexLocker ml(Heap_lock);
975 collect_locked(cause, max_generation);
976 }
977
978 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
979 // The caller has the Heap_lock
980 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
981 collect_locked(cause, OldGen);
982 }
983
984 // this is the private collection interface
985 // The Heap_lock is expected to be held on entry.
986
987 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
988 // Read the GC count while holding the Heap_lock
989 unsigned int gc_count_before = total_collections();
990 unsigned int full_gc_count_before = total_full_collections();
991 {
992 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
993 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
994 cause, max_generation);
995 VMThread::execute(&op);
996 }
997 }
998
999 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1000 do_full_collection(clear_all_soft_refs, OldGen);
1001 }
1002
1003 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
1004 GenerationType last_generation) {
1005 GenerationType local_last_generation;
1006 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
1007 gc_cause() == GCCause::_gc_locker) {
1008 local_last_generation = YoungGen;
1009 } else {
1010 local_last_generation = last_generation;
1011 }
1012
1013 do_collection(true, // full
1014 clear_all_soft_refs, // clear_all_soft_refs
1015 0, // size
1016 false, // is_tlab
1017 local_last_generation); // last_generation
1018 // Hack XXX FIX ME !!!
1019 // A scavenge may not have been attempted, or may have
1020 // been attempted and failed, because the old gen was too full
1021 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1022 incremental_collection_will_fail(false /* don't consult_young */)) {
1023 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1024 // This time allow the old gen to be collected as well
1025 do_collection(true, // full
1026 clear_all_soft_refs, // clear_all_soft_refs
1027 0, // size
1028 false, // is_tlab
1029 OldGen); // last_generation
1030 }
1031 }
1032
1033 bool GenCollectedHeap::is_in_young(oop p) {
1034 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1035 assert(result == _young_gen->is_in_reserved(p),
1036 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1037 return result;
1038 }
1039
1040 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1041 bool GenCollectedHeap::is_in(const void* p) const {
1042 return _young_gen->is_in(p) || _old_gen->is_in(p);
1043 }
1044
1045 #ifdef ASSERT
1046 // Don't implement this by using is_in_young(). This method is used
1047 // in some cases to check that is_in_young() is correct.
1048 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1049 assert(is_in_reserved(p) || p == NULL,
1050 "Does not work if address is non-null and outside of the heap");
1051 return p < _young_gen->reserved().end() && p != NULL;
1052 }
1053 #endif
1054
1055 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
1056 NoHeaderExtendedOopClosure no_header_cl(cl);
1057 oop_iterate(&no_header_cl);
1058 }
1059
1060 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
1061 _young_gen->oop_iterate(cl);
1062 _old_gen->oop_iterate(cl);
1063 }
1064
1065 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1066 _young_gen->object_iterate(cl);
1067 _old_gen->object_iterate(cl);
1068 }
1069
1070 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1071 _young_gen->safe_object_iterate(cl);
1072 _old_gen->safe_object_iterate(cl);
1073 }
1074
1075 Space* GenCollectedHeap::space_containing(const void* addr) const {
1076 Space* res = _young_gen->space_containing(addr);
1077 if (res != NULL) {
1078 return res;
1079 }
1080 res = _old_gen->space_containing(addr);
1081 assert(res != NULL, "Could not find containing space");
1082 return res;
1083 }
1084
1085 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1086 assert(is_in_reserved(addr), "block_start of address outside of heap");
1087 if (_young_gen->is_in_reserved(addr)) {
1088 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1089 return _young_gen->block_start(addr);
1090 }
1091
1092 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1093 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1094 return _old_gen->block_start(addr);
1095 }
1096
1097 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1098 assert(is_in_reserved(addr), "block_size of address outside of heap");
1099 if (_young_gen->is_in_reserved(addr)) {
1100 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1101 return _young_gen->block_size(addr);
1102 }
1103
1104 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1105 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1106 return _old_gen->block_size(addr);
1107 }
1108
1109 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1110 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1111 assert(block_start(addr) == addr, "addr must be a block start");
1112 if (_young_gen->is_in_reserved(addr)) {
1113 return _young_gen->block_is_obj(addr);
1114 }
1115
1116 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1117 return _old_gen->block_is_obj(addr);
1118 }
1119
1120 bool GenCollectedHeap::supports_tlab_allocation() const {
1121 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1122 return _young_gen->supports_tlab_allocation();
1123 }
1124
1125 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1126 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1127 if (_young_gen->supports_tlab_allocation()) {
1128 return _young_gen->tlab_capacity();
1129 }
1130 return 0;
1131 }
1132
1133 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1134 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1135 if (_young_gen->supports_tlab_allocation()) {
1136 return _young_gen->tlab_used();
1137 }
1138 return 0;
1139 }
1140
1141 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1142 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1143 if (_young_gen->supports_tlab_allocation()) {
1144 return _young_gen->unsafe_max_tlab_alloc();
1145 }
1146 return 0;
1147 }
1148
1149 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1150 size_t requested_size,
1151 size_t* actual_size) {
1152 bool gc_overhead_limit_was_exceeded;
1153 HeapWord* result = mem_allocate_work(requested_size /* size */,
1154 true /* is_tlab */,
1155 &gc_overhead_limit_was_exceeded);
1156 if (result != NULL) {
1157 *actual_size = requested_size;
1158 }
1159
1160 return result;
1161 }
1162
1163 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1164 // from the list headed by "*prev_ptr".
1165 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1166 bool first = true;
1167 size_t min_size = 0; // "first" makes this conceptually infinite.
1168 ScratchBlock **smallest_ptr, *smallest;
1169 ScratchBlock *cur = *prev_ptr;
1170 while (cur) {
1171 assert(*prev_ptr == cur, "just checking");
1172 if (first || cur->num_words < min_size) {
1173 smallest_ptr = prev_ptr;
1174 smallest = cur;
1175 min_size = smallest->num_words;
1176 first = false;
1177 }
1178 prev_ptr = &cur->next;
1179 cur = cur->next;
1180 }
1181 smallest = *smallest_ptr;
1182 *smallest_ptr = smallest->next;
1183 return smallest;
1184 }
1185
1186 // Sort the scratch block list headed by res into decreasing size order,
1187 // and set "res" to the result.
1188 static void sort_scratch_list(ScratchBlock*& list) {
1189 ScratchBlock* sorted = NULL;
1190 ScratchBlock* unsorted = list;
1191 while (unsorted) {
1192 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1193 smallest->next = sorted;
1194 sorted = smallest;
1195 }
1196 list = sorted;
1197 }
1198
1199 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1200 size_t max_alloc_words) {
1201 ScratchBlock* res = NULL;
1202 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1203 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1204 sort_scratch_list(res);
1205 return res;
1206 }
1207
1208 void GenCollectedHeap::release_scratch() {
1209 _young_gen->reset_scratch();
1210 _old_gen->reset_scratch();
1211 }
1212
1213 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1214 void do_generation(Generation* gen) {
1215 gen->prepare_for_verify();
1216 }
1217 };
1218
1219 void GenCollectedHeap::prepare_for_verify() {
1220 ensure_parsability(false); // no need to retire TLABs
1221 GenPrepareForVerifyClosure blk;
1222 generation_iterate(&blk, false);
1223 }
1224
1225 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1226 bool old_to_young) {
1227 if (old_to_young) {
1228 cl->do_generation(_old_gen);
1229 cl->do_generation(_young_gen);
1230 } else {
1231 cl->do_generation(_young_gen);
1232 cl->do_generation(_old_gen);
1233 }
1234 }
1235
1236 bool GenCollectedHeap::is_maximal_no_gc() const {
1237 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1238 }
1239
1240 void GenCollectedHeap::save_marks() {
1241 _young_gen->save_marks();
1242 _old_gen->save_marks();
1243 }
1244
1245 GenCollectedHeap* GenCollectedHeap::heap() {
1246 CollectedHeap* heap = Universe::heap();
1247 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1248 assert(heap->kind() == CollectedHeap::Serial ||
1249 heap->kind() == CollectedHeap::CMS, "Invalid name");
1250 return (GenCollectedHeap*) heap;
1251 }
1252
1253 void GenCollectedHeap::prepare_for_compaction() {
1254 // Start by compacting into same gen.
1255 CompactPoint cp(_old_gen);
1256 _old_gen->prepare_for_compaction(&cp);
1257 _young_gen->prepare_for_compaction(&cp);
1258 }
1259
1260 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1261 log_debug(gc, verify)("%s", _old_gen->name());
1262 _old_gen->verify();
1263
1264 log_debug(gc, verify)("%s", _old_gen->name());
1265 _young_gen->verify();
1266
1267 log_debug(gc, verify)("RemSet");
1268 rem_set()->verify();
1269 }
1270
1271 void GenCollectedHeap::print_on(outputStream* st) const {
1272 _young_gen->print_on(st);
1273 _old_gen->print_on(st);
1274 MetaspaceUtils::print_on(st);
1275 }
1276
1277 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1278 }
1279
1280 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1281 }
1282
1283 void GenCollectedHeap::print_tracing_info() const {
1284 if (log_is_enabled(Debug, gc, heap, exit)) {
1285 LogStreamHandle(Debug, gc, heap, exit) lsh;
1286 _young_gen->print_summary_info_on(&lsh);
1287 _old_gen->print_summary_info_on(&lsh);
1288 }
1289 }
1290
1291 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1292 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1293 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1294 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1295 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1296 }
1297
1298 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1299 private:
1300 bool _full;
1301 public:
1302 void do_generation(Generation* gen) {
1303 gen->gc_prologue(_full);
1304 }
1305 GenGCPrologueClosure(bool full) : _full(full) {};
1306 };
1307
1308 void GenCollectedHeap::gc_prologue(bool full) {
1309 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1310
1311 // Fill TLAB's and such
1312 CollectedHeap::accumulate_statistics_all_tlabs();
1313 ensure_parsability(true); // retire TLABs
1314
1315 // Walk generations
1316 GenGCPrologueClosure blk(full);
1317 generation_iterate(&blk, false); // not old-to-young.
1318 };
1319
1320 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1321 private:
1322 bool _full;
1323 public:
1324 void do_generation(Generation* gen) {
1325 gen->gc_epilogue(_full);
1326 }
1327 GenGCEpilogueClosure(bool full) : _full(full) {};
1328 };
1329
1330 void GenCollectedHeap::gc_epilogue(bool full) {
1331 #if COMPILER2_OR_JVMCI
1332 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1333 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1334 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1335 #endif // COMPILER2_OR_JVMCI
1336
1337 resize_all_tlabs();
1338
1339 GenGCEpilogueClosure blk(full);
1340 generation_iterate(&blk, false); // not old-to-young.
1341
1342 if (!CleanChunkPoolAsync) {
1343 Chunk::clean_chunk_pool();
1344 }
1345
1346 MetaspaceCounters::update_performance_counters();
1347 CompressedClassSpaceCounters::update_performance_counters();
1348 };
1349
1350 #ifndef PRODUCT
1351 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1352 private:
1353 public:
1354 void do_generation(Generation* gen) {
1355 gen->record_spaces_top();
1356 }
1357 };
1358
1359 void GenCollectedHeap::record_gen_tops_before_GC() {
1360 if (ZapUnusedHeapArea) {
1361 GenGCSaveTopsBeforeGCClosure blk;
1362 generation_iterate(&blk, false); // not old-to-young.
1363 }
1364 }
1365 #endif // not PRODUCT
1366
1367 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1368 public:
1369 void do_generation(Generation* gen) {
1370 gen->ensure_parsability();
1371 }
1372 };
1373
1374 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1375 CollectedHeap::ensure_parsability(retire_tlabs);
1376 GenEnsureParsabilityClosure ep_cl;
1377 generation_iterate(&ep_cl, false);
1378 }
1379
1380 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1381 oop obj,
1382 size_t obj_size) {
1383 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1384 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1385 HeapWord* result = NULL;
1386
1387 result = old_gen->expand_and_allocate(obj_size, false);
1388
1389 if (result != NULL) {
1390 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1391 }
1392 return oop(result);
1393 }
1394
1395 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1396 jlong _time; // in ms
1397 jlong _now; // in ms
1398
1399 public:
1400 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1401
1402 jlong time() { return _time; }
1403
1404 void do_generation(Generation* gen) {
1405 _time = MIN2(_time, gen->time_of_last_gc(_now));
1406 }
1407 };
1408
1409 jlong GenCollectedHeap::millis_since_last_gc() {
1410 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1411 // provided the underlying platform provides such a time source
1412 // (and it is bug free). So we still have to guard against getting
1413 // back a time later than 'now'.
1414 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1415 GenTimeOfLastGCClosure tolgc_cl(now);
1416 // iterate over generations getting the oldest
1417 // time that a generation was collected
1418 generation_iterate(&tolgc_cl, false);
1419
1420 jlong retVal = now - tolgc_cl.time();
1421 if (retVal < 0) {
1422 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1423 ". returning zero instead.", retVal);
1424 return 0;
1425 }
1426 return retVal;
1427 }