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 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q());
519 rp->enqueue_discovered_references(NULL, &pt);
520 pt.print_enqueue_phase();
521 } else {
522 rp->set_enqueuing_is_done(false);
523 }
524 rp->verify_no_references_recorded();
525 }
526
527 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
528
529 gen->stat_record()->accumulated_time.stop();
530
531 update_gc_stats(gen, full);
532
533 if (run_verification && VerifyAfterGC) {
534 HandleMark hm; // Discard invalid handles created during verification
535 Universe::verify("After GC");
536 }
537 }
538
539 void GenCollectedHeap::do_collection(bool full,
540 bool clear_all_soft_refs,
541 size_t size,
542 bool is_tlab,
543 GenerationType max_generation) {
544 ResourceMark rm;
545 DEBUG_ONLY(Thread* my_thread = Thread::current();)
546
547 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
548 assert(my_thread->is_VM_thread() ||
549 my_thread->is_ConcurrentGC_thread(),
550 "incorrect thread type capability");
551 assert(Heap_lock->is_locked(),
552 "the requesting thread should have the Heap_lock");
553 guarantee(!is_gc_active(), "collection is not reentrant");
554
555 if (GCLocker::check_active_before_gc()) {
556 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
557 }
558
559 GCIdMark gc_id_mark;
560
561 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
562 soft_ref_policy()->should_clear_all_soft_refs();
563
564 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
565
566 const size_t metadata_prev_used = MetaspaceUtils::used_bytes();
567
568 print_heap_before_gc();
569
570 {
571 FlagSetting fl(_is_gc_active, true);
572
573 bool complete = full && (max_generation == OldGen);
574 bool old_collects_young = complete && !ScavengeBeforeFullGC;
575 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
576
577 FormatBuffer<> gc_string("%s", "Pause ");
578 if (do_young_collection) {
579 gc_string.append("Young");
580 } else {
581 gc_string.append("Full");
582 }
583
584 GCTraceCPUTime tcpu;
585 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
586
587 gc_prologue(complete);
588 increment_total_collections(complete);
589
590 size_t young_prev_used = _young_gen->used();
591 size_t old_prev_used = _old_gen->used();
592
593 bool run_verification = total_collections() >= VerifyGCStartAt;
594
595 bool prepared_for_verification = false;
596 bool collected_old = false;
597
598 if (do_young_collection) {
599 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
600 prepare_for_verify();
601 prepared_for_verification = true;
602 }
603
604 collect_generation(_young_gen,
605 full,
606 size,
607 is_tlab,
608 run_verification && VerifyGCLevel <= 0,
609 do_clear_all_soft_refs,
610 false);
611
612 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
613 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
614 // Allocation request was met by young GC.
615 size = 0;
616 }
617 }
618
619 bool must_restore_marks_for_biased_locking = false;
620
621 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
622 if (!complete) {
623 // The full_collections increment was missed above.
624 increment_total_full_collections();
625 }
626
627 if (!prepared_for_verification && run_verification &&
628 VerifyGCLevel <= 1 && VerifyBeforeGC) {
629 prepare_for_verify();
630 }
631
632 if (do_young_collection) {
633 // We did a young GC. Need a new GC id for the old GC.
634 GCIdMark gc_id_mark;
635 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
636 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
637 } else {
638 // No young GC done. Use the same GC id as was set up earlier in this method.
639 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
640 }
641
642 must_restore_marks_for_biased_locking = true;
643 collected_old = true;
644 }
645
646 // Update "complete" boolean wrt what actually transpired --
647 // for instance, a promotion failure could have led to
648 // a whole heap collection.
649 complete = complete || collected_old;
650
651 print_heap_change(young_prev_used, old_prev_used);
652 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
653
654 // Adjust generation sizes.
655 if (collected_old) {
656 _old_gen->compute_new_size();
657 }
658 _young_gen->compute_new_size();
659
660 if (complete) {
661 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
662 ClassLoaderDataGraph::purge();
663 MetaspaceUtils::verify_metrics();
664 // Resize the metaspace capacity after full collections
665 MetaspaceGC::compute_new_size();
666 update_full_collections_completed();
667 }
668
669 // Track memory usage and detect low memory after GC finishes
670 MemoryService::track_memory_usage();
671
672 gc_epilogue(complete);
673
674 if (must_restore_marks_for_biased_locking) {
675 BiasedLocking::restore_marks();
676 }
677 }
678
679 print_heap_after_gc();
680
681 #ifdef TRACESPINNING
682 ParallelTaskTerminator::print_termination_counts();
683 #endif
684 }
685
686 void GenCollectedHeap::register_nmethod(nmethod* nm) {
687 CodeCache::register_scavenge_root_nmethod(nm);
688 }
689
690 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
691 CodeCache::verify_scavenge_root_nmethod(nm);
692 }
693
694 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
695 GCCauseSetter x(this, GCCause::_allocation_failure);
696 HeapWord* result = NULL;
697
698 assert(size != 0, "Precondition violated");
699 if (GCLocker::is_active_and_needs_gc()) {
700 // GC locker is active; instead of a collection we will attempt
701 // to expand the heap, if there's room for expansion.
702 if (!is_maximal_no_gc()) {
703 result = expand_heap_and_allocate(size, is_tlab);
704 }
705 return result; // Could be null if we are out of space.
706 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
707 // Do an incremental collection.
708 do_collection(false, // full
709 false, // clear_all_soft_refs
710 size, // size
711 is_tlab, // is_tlab
712 GenCollectedHeap::OldGen); // max_generation
713 } else {
714 log_trace(gc)(" :: Trying full because partial may fail :: ");
715 // Try a full collection; see delta for bug id 6266275
716 // for the original code and why this has been simplified
717 // with from-space allocation criteria modified and
718 // such allocation moved out of the safepoint path.
719 do_collection(true, // full
720 false, // clear_all_soft_refs
721 size, // size
722 is_tlab, // is_tlab
723 GenCollectedHeap::OldGen); // max_generation
724 }
725
726 result = attempt_allocation(size, is_tlab, false /*first_only*/);
727
728 if (result != NULL) {
729 assert(is_in_reserved(result), "result not in heap");
730 return result;
731 }
732
733 // OK, collection failed, try expansion.
734 result = expand_heap_and_allocate(size, is_tlab);
735 if (result != NULL) {
736 return result;
737 }
738
739 // If we reach this point, we're really out of memory. Try every trick
740 // we can to reclaim memory. Force collection of soft references. Force
741 // a complete compaction of the heap. Any additional methods for finding
742 // free memory should be here, especially if they are expensive. If this
743 // attempt fails, an OOM exception will be thrown.
744 {
745 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
746
747 do_collection(true, // full
748 true, // clear_all_soft_refs
749 size, // size
750 is_tlab, // is_tlab
751 GenCollectedHeap::OldGen); // max_generation
752 }
753
754 result = attempt_allocation(size, is_tlab, false /* first_only */);
755 if (result != NULL) {
756 assert(is_in_reserved(result), "result not in heap");
757 return result;
758 }
759
760 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
761 "Flag should have been handled and cleared prior to this point");
762
763 // What else? We might try synchronous finalization later. If the total
764 // space available is large enough for the allocation, then a more
765 // complete compaction phase than we've tried so far might be
766 // appropriate.
767 return NULL;
768 }
769
770 #ifdef ASSERT
771 class AssertNonScavengableClosure: public OopClosure {
772 public:
773 virtual void do_oop(oop* p) {
774 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
775 "Referent should not be scavengable."); }
776 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
777 };
778 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
779 #endif
780
781 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
782 ScanningOption so,
783 OopClosure* strong_roots,
784 OopClosure* weak_roots,
785 CLDClosure* strong_cld_closure,
786 CLDClosure* weak_cld_closure,
787 CodeBlobToOopClosure* code_roots) {
788 // General roots.
789 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
790 assert(code_roots != NULL, "code root closure should always be set");
791 // _n_termination for _process_strong_tasks should be set up stream
792 // in a method not running in a GC worker. Otherwise the GC worker
793 // could be trying to change the termination condition while the task
794 // is executing in another GC worker.
795
796 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
797 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
798 }
799
800 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
801 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
802
803 bool is_par = scope->n_threads() > 1;
804 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
805
806 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
807 Universe::oops_do(strong_roots);
808 }
809 // Global (strong) JNI handles
810 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
811 JNIHandles::oops_do(strong_roots);
812 }
813
814 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
815 ObjectSynchronizer::oops_do(strong_roots);
816 }
817 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
818 Management::oops_do(strong_roots);
819 }
820 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
821 JvmtiExport::oops_do(strong_roots);
822 }
823 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
824 AOTLoader::oops_do(strong_roots);
825 }
826
827 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
828 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
829 }
830
831 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
832 if (so & SO_ScavengeCodeCache) {
833 assert(code_roots != NULL, "must supply closure for code cache");
834
835 // We only visit parts of the CodeCache when scavenging.
836 CodeCache::scavenge_root_nmethods_do(code_roots);
837 }
838 if (so & SO_AllCodeCache) {
839 assert(code_roots != NULL, "must supply closure for code cache");
840
841 // CMSCollector uses this to do intermediate-strength collections.
842 // We scan the entire code cache, since CodeCache::do_unloading is not called.
843 CodeCache::blobs_do(code_roots);
844 }
845 // Verify that the code cache contents are not subject to
846 // movement by a scavenging collection.
847 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
848 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
849 }
850 }
851
852 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
853 OopClosure* root_closure) {
854 assert(root_closure != NULL, "Must be set");
855 // All threads execute the following. A specific chunk of buckets
856 // from the StringTable are the individual tasks.
857 if (scope->n_threads() > 1) {
858 StringTable::possibly_parallel_oops_do(root_closure);
859 } else {
860 StringTable::oops_do(root_closure);
861 }
862 }
863
864 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
865 OopsInGenClosure* root_closure,
866 OopsInGenClosure* old_gen_closure,
867 CLDClosure* cld_closure) {
868 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
869
870 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
871 cld_closure, cld_closure, &mark_code_closure);
872 process_string_table_roots(scope, root_closure);
873
874 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
875 root_closure->reset_generation();
876 }
877
878 // When collection is parallel, all threads get to cooperate to do
879 // old generation scanning.
880 old_gen_closure->set_generation(_old_gen);
881 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
882 old_gen_closure->reset_generation();
883
884 _process_strong_tasks->all_tasks_completed(scope->n_threads());
885 }
886
887 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
888 bool is_adjust_phase,
889 ScanningOption so,
890 bool only_strong_roots,
891 OopsInGenClosure* root_closure,
892 CLDClosure* cld_closure) {
893 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
894 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
895 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
896
897 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
898 if (is_adjust_phase) {
899 // We never treat the string table as roots during marking
900 // for the full gc, so we only need to process it during
901 // the adjust phase.
902 process_string_table_roots(scope, root_closure);
903 }
904
905 _process_strong_tasks->all_tasks_completed(scope->n_threads());
906 }
907
908 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
909 WeakProcessor::oops_do(root_closure);
910 _young_gen->ref_processor()->weak_oops_do(root_closure);
911 _old_gen->ref_processor()->weak_oops_do(root_closure);
912 }
913
914 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
915 void GenCollectedHeap:: \
916 oop_since_save_marks_iterate(GenerationType gen, \
917 OopClosureType* cur, \
918 OopClosureType* older) { \
919 if (gen == YoungGen) { \
920 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
921 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
922 } else { \
923 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
924 } \
925 }
926
927 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
928
929 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
930
931 bool GenCollectedHeap::no_allocs_since_save_marks() {
932 return _young_gen->no_allocs_since_save_marks() &&
933 _old_gen->no_allocs_since_save_marks();
934 }
935
936 bool GenCollectedHeap::supports_inline_contig_alloc() const {
937 return _young_gen->supports_inline_contig_alloc();
938 }
939
940 HeapWord* volatile* GenCollectedHeap::top_addr() const {
941 return _young_gen->top_addr();
942 }
943
944 HeapWord** GenCollectedHeap::end_addr() const {
945 return _young_gen->end_addr();
946 }
947
948 // public collection interfaces
949
950 void GenCollectedHeap::collect(GCCause::Cause cause) {
951 if (cause == GCCause::_wb_young_gc) {
952 // Young collection for the WhiteBox API.
953 collect(cause, YoungGen);
954 } else {
955 #ifdef ASSERT
956 if (cause == GCCause::_scavenge_alot) {
957 // Young collection only.
958 collect(cause, YoungGen);
959 } else {
960 // Stop-the-world full collection.
961 collect(cause, OldGen);
962 }
963 #else
964 // Stop-the-world full collection.
965 collect(cause, OldGen);
966 #endif
967 }
968 }
969
970 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
971 // The caller doesn't have the Heap_lock
972 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
973 MutexLocker ml(Heap_lock);
974 collect_locked(cause, max_generation);
975 }
976
977 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
978 // The caller has the Heap_lock
979 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
980 collect_locked(cause, OldGen);
981 }
982
983 // this is the private collection interface
984 // The Heap_lock is expected to be held on entry.
985
986 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
987 // Read the GC count while holding the Heap_lock
988 unsigned int gc_count_before = total_collections();
989 unsigned int full_gc_count_before = total_full_collections();
990 {
991 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
992 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
993 cause, max_generation);
994 VMThread::execute(&op);
995 }
996 }
997
998 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
999 do_full_collection(clear_all_soft_refs, OldGen);
1000 }
1001
1002 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
1003 GenerationType last_generation) {
1004 GenerationType local_last_generation;
1005 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
1006 gc_cause() == GCCause::_gc_locker) {
1007 local_last_generation = YoungGen;
1008 } else {
1009 local_last_generation = last_generation;
1010 }
1011
1012 do_collection(true, // full
1013 clear_all_soft_refs, // clear_all_soft_refs
1014 0, // size
1015 false, // is_tlab
1016 local_last_generation); // last_generation
1017 // Hack XXX FIX ME !!!
1018 // A scavenge may not have been attempted, or may have
1019 // been attempted and failed, because the old gen was too full
1020 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1021 incremental_collection_will_fail(false /* don't consult_young */)) {
1022 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1023 // This time allow the old gen to be collected as well
1024 do_collection(true, // full
1025 clear_all_soft_refs, // clear_all_soft_refs
1026 0, // size
1027 false, // is_tlab
1028 OldGen); // last_generation
1029 }
1030 }
1031
1032 bool GenCollectedHeap::is_in_young(oop p) {
1033 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1034 assert(result == _young_gen->is_in_reserved(p),
1035 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1036 return result;
1037 }
1038
1039 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1040 bool GenCollectedHeap::is_in(const void* p) const {
1041 return _young_gen->is_in(p) || _old_gen->is_in(p);
1042 }
1043
1044 #ifdef ASSERT
1045 // Don't implement this by using is_in_young(). This method is used
1046 // in some cases to check that is_in_young() is correct.
1047 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1048 assert(is_in_reserved(p) || p == NULL,
1049 "Does not work if address is non-null and outside of the heap");
1050 return p < _young_gen->reserved().end() && p != NULL;
1051 }
1052 #endif
1053
1054 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
1055 NoHeaderExtendedOopClosure no_header_cl(cl);
1056 oop_iterate(&no_header_cl);
1057 }
1058
1059 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
1060 _young_gen->oop_iterate(cl);
1061 _old_gen->oop_iterate(cl);
1062 }
1063
1064 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1065 _young_gen->object_iterate(cl);
1066 _old_gen->object_iterate(cl);
1067 }
1068
1069 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1070 _young_gen->safe_object_iterate(cl);
1071 _old_gen->safe_object_iterate(cl);
1072 }
1073
1074 Space* GenCollectedHeap::space_containing(const void* addr) const {
1075 Space* res = _young_gen->space_containing(addr);
1076 if (res != NULL) {
1077 return res;
1078 }
1079 res = _old_gen->space_containing(addr);
1080 assert(res != NULL, "Could not find containing space");
1081 return res;
1082 }
1083
1084 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1085 assert(is_in_reserved(addr), "block_start of address outside of heap");
1086 if (_young_gen->is_in_reserved(addr)) {
1087 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1088 return _young_gen->block_start(addr);
1089 }
1090
1091 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1092 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1093 return _old_gen->block_start(addr);
1094 }
1095
1096 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1097 assert(is_in_reserved(addr), "block_size of address outside of heap");
1098 if (_young_gen->is_in_reserved(addr)) {
1099 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1100 return _young_gen->block_size(addr);
1101 }
1102
1103 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1104 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1105 return _old_gen->block_size(addr);
1106 }
1107
1108 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1109 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1110 assert(block_start(addr) == addr, "addr must be a block start");
1111 if (_young_gen->is_in_reserved(addr)) {
1112 return _young_gen->block_is_obj(addr);
1113 }
1114
1115 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1116 return _old_gen->block_is_obj(addr);
1117 }
1118
1119 bool GenCollectedHeap::supports_tlab_allocation() const {
1120 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1121 return _young_gen->supports_tlab_allocation();
1122 }
1123
1124 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1125 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1126 if (_young_gen->supports_tlab_allocation()) {
1127 return _young_gen->tlab_capacity();
1128 }
1129 return 0;
1130 }
1131
1132 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1133 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1134 if (_young_gen->supports_tlab_allocation()) {
1135 return _young_gen->tlab_used();
1136 }
1137 return 0;
1138 }
1139
1140 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1141 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1142 if (_young_gen->supports_tlab_allocation()) {
1143 return _young_gen->unsafe_max_tlab_alloc();
1144 }
1145 return 0;
1146 }
1147
1148 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1149 bool gc_overhead_limit_was_exceeded;
1150 return mem_allocate_work(size /* size */,
1151 true /* is_tlab */,
1152 &gc_overhead_limit_was_exceeded);
1153 }
1154
1155 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1156 // from the list headed by "*prev_ptr".
1157 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1158 bool first = true;
1159 size_t min_size = 0; // "first" makes this conceptually infinite.
1160 ScratchBlock **smallest_ptr, *smallest;
1161 ScratchBlock *cur = *prev_ptr;
1162 while (cur) {
1163 assert(*prev_ptr == cur, "just checking");
1164 if (first || cur->num_words < min_size) {
1165 smallest_ptr = prev_ptr;
1166 smallest = cur;
1167 min_size = smallest->num_words;
1168 first = false;
1169 }
1170 prev_ptr = &cur->next;
1171 cur = cur->next;
1172 }
1173 smallest = *smallest_ptr;
1174 *smallest_ptr = smallest->next;
1175 return smallest;
1176 }
1177
1178 // Sort the scratch block list headed by res into decreasing size order,
1179 // and set "res" to the result.
1180 static void sort_scratch_list(ScratchBlock*& list) {
1181 ScratchBlock* sorted = NULL;
1182 ScratchBlock* unsorted = list;
1183 while (unsorted) {
1184 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1185 smallest->next = sorted;
1186 sorted = smallest;
1187 }
1188 list = sorted;
1189 }
1190
1191 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1192 size_t max_alloc_words) {
1193 ScratchBlock* res = NULL;
1194 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1195 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1196 sort_scratch_list(res);
1197 return res;
1198 }
1199
1200 void GenCollectedHeap::release_scratch() {
1201 _young_gen->reset_scratch();
1202 _old_gen->reset_scratch();
1203 }
1204
1205 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1206 void do_generation(Generation* gen) {
1207 gen->prepare_for_verify();
1208 }
1209 };
1210
1211 void GenCollectedHeap::prepare_for_verify() {
1212 ensure_parsability(false); // no need to retire TLABs
1213 GenPrepareForVerifyClosure blk;
1214 generation_iterate(&blk, false);
1215 }
1216
1217 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1218 bool old_to_young) {
1219 if (old_to_young) {
1220 cl->do_generation(_old_gen);
1221 cl->do_generation(_young_gen);
1222 } else {
1223 cl->do_generation(_young_gen);
1224 cl->do_generation(_old_gen);
1225 }
1226 }
1227
1228 bool GenCollectedHeap::is_maximal_no_gc() const {
1229 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1230 }
1231
1232 void GenCollectedHeap::save_marks() {
1233 _young_gen->save_marks();
1234 _old_gen->save_marks();
1235 }
1236
1237 GenCollectedHeap* GenCollectedHeap::heap() {
1238 CollectedHeap* heap = Universe::heap();
1239 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1240 assert(heap->kind() == CollectedHeap::Serial ||
1241 heap->kind() == CollectedHeap::CMS, "Invalid name");
1242 return (GenCollectedHeap*) heap;
1243 }
1244
1245 void GenCollectedHeap::prepare_for_compaction() {
1246 // Start by compacting into same gen.
1247 CompactPoint cp(_old_gen);
1248 _old_gen->prepare_for_compaction(&cp);
1249 _young_gen->prepare_for_compaction(&cp);
1250 }
1251
1252 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1253 log_debug(gc, verify)("%s", _old_gen->name());
1254 _old_gen->verify();
1255
1256 log_debug(gc, verify)("%s", _old_gen->name());
1257 _young_gen->verify();
1258
1259 log_debug(gc, verify)("RemSet");
1260 rem_set()->verify();
1261 }
1262
1263 void GenCollectedHeap::print_on(outputStream* st) const {
1264 _young_gen->print_on(st);
1265 _old_gen->print_on(st);
1266 MetaspaceUtils::print_on(st);
1267 }
1268
1269 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1270 }
1271
1272 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1273 }
1274
1275 void GenCollectedHeap::print_tracing_info() const {
1276 if (log_is_enabled(Debug, gc, heap, exit)) {
1277 LogStreamHandle(Debug, gc, heap, exit) lsh;
1278 _young_gen->print_summary_info_on(&lsh);
1279 _old_gen->print_summary_info_on(&lsh);
1280 }
1281 }
1282
1283 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1284 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1285 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1286 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1287 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1288 }
1289
1290 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1291 private:
1292 bool _full;
1293 public:
1294 void do_generation(Generation* gen) {
1295 gen->gc_prologue(_full);
1296 }
1297 GenGCPrologueClosure(bool full) : _full(full) {};
1298 };
1299
1300 void GenCollectedHeap::gc_prologue(bool full) {
1301 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1302
1303 // Fill TLAB's and such
1304 CollectedHeap::accumulate_statistics_all_tlabs();
1305 ensure_parsability(true); // retire TLABs
1306
1307 // Walk generations
1308 GenGCPrologueClosure blk(full);
1309 generation_iterate(&blk, false); // not old-to-young.
1310 };
1311
1312 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1313 private:
1314 bool _full;
1315 public:
1316 void do_generation(Generation* gen) {
1317 gen->gc_epilogue(_full);
1318 }
1319 GenGCEpilogueClosure(bool full) : _full(full) {};
1320 };
1321
1322 void GenCollectedHeap::gc_epilogue(bool full) {
1323 #if COMPILER2_OR_JVMCI
1324 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1325 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1326 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1327 #endif // COMPILER2_OR_JVMCI
1328
1329 resize_all_tlabs();
1330
1331 GenGCEpilogueClosure blk(full);
1332 generation_iterate(&blk, false); // not old-to-young.
1333
1334 if (!CleanChunkPoolAsync) {
1335 Chunk::clean_chunk_pool();
1336 }
1337
1338 MetaspaceCounters::update_performance_counters();
1339 CompressedClassSpaceCounters::update_performance_counters();
1340 };
1341
1342 #ifndef PRODUCT
1343 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1344 private:
1345 public:
1346 void do_generation(Generation* gen) {
1347 gen->record_spaces_top();
1348 }
1349 };
1350
1351 void GenCollectedHeap::record_gen_tops_before_GC() {
1352 if (ZapUnusedHeapArea) {
1353 GenGCSaveTopsBeforeGCClosure blk;
1354 generation_iterate(&blk, false); // not old-to-young.
1355 }
1356 }
1357 #endif // not PRODUCT
1358
1359 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1360 public:
1361 void do_generation(Generation* gen) {
1362 gen->ensure_parsability();
1363 }
1364 };
1365
1366 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1367 CollectedHeap::ensure_parsability(retire_tlabs);
1368 GenEnsureParsabilityClosure ep_cl;
1369 generation_iterate(&ep_cl, false);
1370 }
1371
1372 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1373 oop obj,
1374 size_t obj_size) {
1375 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1376 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1377 HeapWord* result = NULL;
1378
1379 result = old_gen->expand_and_allocate(obj_size, false);
1380
1381 if (result != NULL) {
1382 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1383 }
1384 return oop(result);
1385 }
1386
1387 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1388 jlong _time; // in ms
1389 jlong _now; // in ms
1390
1391 public:
1392 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1393
1394 jlong time() { return _time; }
1395
1396 void do_generation(Generation* gen) {
1397 _time = MIN2(_time, gen->time_of_last_gc(_now));
1398 }
1399 };
1400
1401 jlong GenCollectedHeap::millis_since_last_gc() {
1402 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1403 // provided the underlying platform provides such a time source
1404 // (and it is bug free). So we still have to guard against getting
1405 // back a time later than 'now'.
1406 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1407 GenTimeOfLastGCClosure tolgc_cl(now);
1408 // iterate over generations getting the oldest
1409 // time that a generation was collected
1410 generation_iterate(&tolgc_cl, false);
1411
1412 jlong retVal = now - tolgc_cl.time();
1413 if (retVal < 0) {
1414 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1415 ". returning zero instead.", retVal);
1416 return 0;
1417 }
1418 return retVal;
1419 }