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