1 /*
2 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "aot/aotLoader.hpp"
27 #include "classfile/symbolTable.hpp"
28 #include "classfile/stringTable.hpp"
29 #include "classfile/systemDictionary.hpp"
30 #include "classfile/vmSymbols.hpp"
31 #include "code/codeCache.hpp"
32 #include "code/icBuffer.hpp"
33 #include "gc/serial/defNewGeneration.hpp"
34 #include "gc/shared/adaptiveSizePolicy.hpp"
35 #include "gc/shared/cardTableBarrierSet.hpp"
36 #include "gc/shared/cardTableRS.hpp"
37 #include "gc/shared/collectedHeap.inline.hpp"
38 #include "gc/shared/collectorCounters.hpp"
39 #include "gc/shared/gcId.hpp"
40 #include "gc/shared/gcLocker.hpp"
41 #include "gc/shared/gcPolicyCounters.hpp"
42 #include "gc/shared/gcTrace.hpp"
43 #include "gc/shared/gcTraceTime.inline.hpp"
44 #include "gc/shared/genCollectedHeap.hpp"
45 #include "gc/shared/genOopClosures.inline.hpp"
46 #include "gc/shared/generationSpec.hpp"
47 #include "gc/shared/oopStorageParState.inline.hpp"
48 #include "gc/shared/space.hpp"
49 #include "gc/shared/strongRootsScope.hpp"
50 #include "gc/shared/vmGCOperations.hpp"
51 #include "gc/shared/weakProcessor.hpp"
52 #include "gc/shared/workgroup.hpp"
53 #include "memory/filemap.hpp"
54 #include "memory/metaspaceCounters.hpp"
55 #include "memory/resourceArea.hpp"
56 #include "oops/oop.inline.hpp"
57 #include "runtime/biasedLocking.hpp"
58 #include "runtime/flags/flagSetting.hpp"
59 #include "runtime/handles.hpp"
60 #include "runtime/handles.inline.hpp"
61 #include "runtime/java.hpp"
62 #include "runtime/vmThread.hpp"
63 #include "services/management.hpp"
64 #include "services/memoryService.hpp"
65 #include "utilities/debug.hpp"
66 #include "utilities/formatBuffer.hpp"
67 #include "utilities/macros.hpp"
68 #include "utilities/stack.inline.hpp"
69 #include "utilities/vmError.hpp"
70
71 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy,
72 Generation::Name young,
73 Generation::Name old,
74 const char* policy_counters_name) :
75 CollectedHeap(),
76 _rem_set(NULL),
77 _young_gen_spec(new GenerationSpec(young,
78 policy->initial_young_size(),
79 policy->max_young_size(),
80 policy->gen_alignment())),
81 _old_gen_spec(new GenerationSpec(old,
82 policy->initial_old_size(),
83 policy->max_old_size(),
84 policy->gen_alignment())),
85 _gen_policy(policy),
86 _soft_ref_gen_policy(),
87 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
88 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
89 _full_collections_completed(0) {
90 }
91
92 jint GenCollectedHeap::initialize() {
93 // While there are no constraints in the GC code that HeapWordSize
94 // be any particular value, there are multiple other areas in the
95 // system which believe this to be true (e.g. oop->object_size in some
96 // cases incorrectly returns the size in wordSize units rather than
97 // HeapWordSize).
98 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
99
100 // Allocate space for the heap.
101
102 char* heap_address;
103 ReservedSpace heap_rs;
104
105 size_t heap_alignment = collector_policy()->heap_alignment();
106
107 heap_address = allocate(heap_alignment, &heap_rs);
108
109 if (!heap_rs.is_reserved()) {
110 vm_shutdown_during_initialization(
111 "Could not reserve enough space for object heap");
112 return JNI_ENOMEM;
113 }
114
115 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
116
117 _rem_set = create_rem_set(reserved_region());
118 _rem_set->initialize();
119 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
120 bs->initialize();
121 BarrierSet::set_barrier_set(bs);
122
123 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false);
124 _young_gen = _young_gen_spec->init(young_rs, rem_set());
125 heap_rs = heap_rs.last_part(_young_gen_spec->max_size());
126
127 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false);
128 _old_gen = _old_gen_spec->init(old_rs, rem_set());
129 clear_incremental_collection_failed();
130
131 return JNI_OK;
132 }
133
134 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
135 return new CardTableRS(reserved_region, false /* scan_concurrently */);
136 }
137
138 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
139 size_t init_promo_size,
140 size_t init_survivor_size) {
141 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
142 _size_policy = new AdaptiveSizePolicy(init_eden_size,
143 init_promo_size,
144 init_survivor_size,
145 max_gc_pause_sec,
146 GCTimeRatio);
147 }
148
149 char* GenCollectedHeap::allocate(size_t alignment,
150 ReservedSpace* heap_rs){
151 // Now figure out the total size.
152 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
153 assert(alignment % pageSize == 0, "Must be");
154
155 // Check for overflow.
156 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
157 if (total_reserved < _young_gen_spec->max_size()) {
158 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
159 "the maximum representable size");
160 }
161 assert(total_reserved % alignment == 0,
162 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
163 SIZE_FORMAT, total_reserved, alignment);
164
165 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
166
167 os::trace_page_sizes("Heap",
168 collector_policy()->min_heap_byte_size(),
169 total_reserved,
170 alignment,
171 heap_rs->base(),
172 heap_rs->size());
173
174 return heap_rs->base();
175 }
176
177 void GenCollectedHeap::post_initialize() {
178 CollectedHeap::post_initialize();
179 ref_processing_init();
180
181 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
182
183 initialize_size_policy(def_new_gen->eden()->capacity(),
184 _old_gen->capacity(),
185 def_new_gen->from()->capacity());
186
187 MarkSweep::initialize();
188 }
189
190 void GenCollectedHeap::ref_processing_init() {
191 _young_gen->ref_processor_init();
192 _old_gen->ref_processor_init();
193 }
194
195 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
196 return _young_gen_spec;
197 }
198
199 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
200 return _old_gen_spec;
201 }
202
203 size_t GenCollectedHeap::capacity() const {
204 return _young_gen->capacity() + _old_gen->capacity();
205 }
206
207 size_t GenCollectedHeap::used() const {
208 return _young_gen->used() + _old_gen->used();
209 }
210
211 void GenCollectedHeap::save_used_regions() {
212 _old_gen->save_used_region();
213 _young_gen->save_used_region();
214 }
215
216 size_t GenCollectedHeap::max_capacity() const {
217 return _young_gen->max_capacity() + _old_gen->max_capacity();
218 }
219
220 // Update the _full_collections_completed counter
221 // at the end of a stop-world full GC.
222 unsigned int GenCollectedHeap::update_full_collections_completed() {
223 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
224 assert(_full_collections_completed <= _total_full_collections,
225 "Can't complete more collections than were started");
226 _full_collections_completed = _total_full_collections;
227 ml.notify_all();
228 return _full_collections_completed;
229 }
230
231 // Update the _full_collections_completed counter, as appropriate,
232 // at the end of a concurrent GC cycle. Note the conditional update
233 // below to allow this method to be called by a concurrent collector
234 // without synchronizing in any manner with the VM thread (which
235 // may already have initiated a STW full collection "concurrently").
236 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
237 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
238 assert((_full_collections_completed <= _total_full_collections) &&
239 (count <= _total_full_collections),
240 "Can't complete more collections than were started");
241 if (count > _full_collections_completed) {
242 _full_collections_completed = count;
243 ml.notify_all();
244 }
245 return _full_collections_completed;
246 }
247
248 // Return true if any of the following is true:
249 // . the allocation won't fit into the current young gen heap
250 // . gc locker is occupied (jni critical section)
251 // . heap memory is tight -- the most recent previous collection
252 // was a full collection because a partial collection (would
253 // have) failed and is likely to fail again
254 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
255 size_t young_capacity = _young_gen->capacity_before_gc();
256 return (word_size > heap_word_size(young_capacity))
257 || GCLocker::is_active_and_needs_gc()
258 || incremental_collection_failed();
259 }
260
261 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
262 HeapWord* result = NULL;
263 if (_old_gen->should_allocate(size, is_tlab)) {
264 result = _old_gen->expand_and_allocate(size, is_tlab);
265 }
266 if (result == NULL) {
267 if (_young_gen->should_allocate(size, is_tlab)) {
268 result = _young_gen->expand_and_allocate(size, is_tlab);
269 }
270 }
271 assert(result == NULL || is_in_reserved(result), "result not in heap");
272 return result;
273 }
274
275 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
276 bool is_tlab,
277 bool* gc_overhead_limit_was_exceeded) {
278 debug_only(check_for_valid_allocation_state());
279 assert(no_gc_in_progress(), "Allocation during gc not allowed");
280
281 // In general gc_overhead_limit_was_exceeded should be false so
282 // set it so here and reset it to true only if the gc time
283 // limit is being exceeded as checked below.
284 *gc_overhead_limit_was_exceeded = false;
285
286 HeapWord* result = NULL;
287
288 // Loop until the allocation is satisfied, or unsatisfied after GC.
289 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
290 HandleMark hm; // Discard any handles allocated in each iteration.
291
292 // First allocation attempt is lock-free.
293 Generation *young = _young_gen;
294 assert(young->supports_inline_contig_alloc(),
295 "Otherwise, must do alloc within heap lock");
296 if (young->should_allocate(size, is_tlab)) {
297 result = young->par_allocate(size, is_tlab);
298 if (result != NULL) {
299 assert(is_in_reserved(result), "result not in heap");
300 return result;
301 }
302 }
303 uint gc_count_before; // Read inside the Heap_lock locked region.
304 {
305 MutexLocker ml(Heap_lock);
306 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
307 // Note that only large objects get a shot at being
308 // allocated in later generations.
309 bool first_only = !should_try_older_generation_allocation(size);
310
311 result = attempt_allocation(size, is_tlab, first_only);
312 if (result != NULL) {
313 assert(is_in_reserved(result), "result not in heap");
314 return result;
315 }
316
317 if (GCLocker::is_active_and_needs_gc()) {
318 if (is_tlab) {
319 return NULL; // Caller will retry allocating individual object.
320 }
321 if (!is_maximal_no_gc()) {
322 // Try and expand heap to satisfy request.
323 result = expand_heap_and_allocate(size, is_tlab);
324 // Result could be null if we are out of space.
325 if (result != NULL) {
326 return result;
327 }
328 }
329
330 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
331 return NULL; // We didn't get to do a GC and we didn't get any memory.
332 }
333
334 // If this thread is not in a jni critical section, we stall
335 // the requestor until the critical section has cleared and
336 // GC allowed. When the critical section clears, a GC is
337 // initiated by the last thread exiting the critical section; so
338 // we retry the allocation sequence from the beginning of the loop,
339 // rather than causing more, now probably unnecessary, GC attempts.
340 JavaThread* jthr = JavaThread::current();
341 if (!jthr->in_critical()) {
342 MutexUnlocker mul(Heap_lock);
343 // Wait for JNI critical section to be exited
344 GCLocker::stall_until_clear();
345 gclocker_stalled_count += 1;
346 continue;
347 } else {
348 if (CheckJNICalls) {
349 fatal("Possible deadlock due to allocating while"
350 " in jni critical section");
351 }
352 return NULL;
353 }
354 }
355
356 // Read the gc count while the heap lock is held.
357 gc_count_before = total_collections();
358 }
359
360 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
361 VMThread::execute(&op);
362 if (op.prologue_succeeded()) {
363 result = op.result();
364 if (op.gc_locked()) {
365 assert(result == NULL, "must be NULL if gc_locked() is true");
366 continue; // Retry and/or stall as necessary.
367 }
368
369 // Allocation has failed and a collection
370 // has been done. If the gc time limit was exceeded the
371 // this time, return NULL so that an out-of-memory
372 // will be thrown. Clear gc_overhead_limit_exceeded
373 // so that the overhead exceeded does not persist.
374
375 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
376 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
377
378 if (limit_exceeded && softrefs_clear) {
379 *gc_overhead_limit_was_exceeded = true;
380 size_policy()->set_gc_overhead_limit_exceeded(false);
381 if (op.result() != NULL) {
382 CollectedHeap::fill_with_object(op.result(), size);
383 }
384 return NULL;
385 }
386 assert(result == NULL || is_in_reserved(result),
387 "result not in heap");
388 return result;
389 }
390
391 // Give a warning if we seem to be looping forever.
392 if ((QueuedAllocationWarningCount > 0) &&
393 (try_count % QueuedAllocationWarningCount == 0)) {
394 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
395 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
396 }
397 }
398 }
399
400 #ifndef PRODUCT
401 // Override of memory state checking method in CollectedHeap:
402 // Some collectors (CMS for example) can't have badHeapWordVal written
403 // in the first two words of an object. (For instance , in the case of
404 // CMS these words hold state used to synchronize between certain
405 // (concurrent) GC steps and direct allocating mutators.)
406 // The skip_header_HeapWords() method below, allows us to skip
407 // over the requisite number of HeapWord's. Note that (for
408 // generational collectors) this means that those many words are
409 // skipped in each object, irrespective of the generation in which
410 // that object lives. The resultant loss of precision seems to be
411 // harmless and the pain of avoiding that imprecision appears somewhat
412 // higher than we are prepared to pay for such rudimentary debugging
413 // support.
414 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
415 size_t size) {
416 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
417 // We are asked to check a size in HeapWords,
418 // but the memory is mangled in juint words.
419 juint* start = (juint*) (addr + skip_header_HeapWords());
420 juint* end = (juint*) (addr + size);
421 for (juint* slot = start; slot < end; slot += 1) {
422 assert(*slot == badHeapWordVal,
423 "Found non badHeapWordValue in pre-allocation check");
424 }
425 }
426 }
427 #endif
428
429 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
430 bool is_tlab,
431 bool first_only) {
432 HeapWord* res = NULL;
433
434 if (_young_gen->should_allocate(size, is_tlab)) {
435 res = _young_gen->allocate(size, is_tlab);
436 if (res != NULL || first_only) {
437 return res;
438 }
439 }
440
441 if (_old_gen->should_allocate(size, is_tlab)) {
442 res = _old_gen->allocate(size, is_tlab);
443 }
444
445 return res;
446 }
447
448 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
449 bool* gc_overhead_limit_was_exceeded) {
450 return mem_allocate_work(size,
451 false /* is_tlab */,
452 gc_overhead_limit_was_exceeded);
453 }
454
455 bool GenCollectedHeap::must_clear_all_soft_refs() {
456 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
457 _gc_cause == GCCause::_wb_full_gc;
458 }
459
460 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
461 bool is_tlab, bool run_verification, bool clear_soft_refs,
462 bool restore_marks_for_biased_locking) {
463 FormatBuffer<> title("Collect gen: %s", gen->short_name());
464 GCTraceTime(Trace, gc, phases) t1(title);
465 TraceCollectorStats tcs(gen->counters());
466 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
467
468 gen->stat_record()->invocations++;
469 gen->stat_record()->accumulated_time.start();
470
471 // Must be done anew before each collection because
472 // a previous collection will do mangling and will
473 // change top of some spaces.
474 record_gen_tops_before_GC();
475
476 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
477
478 if (run_verification && VerifyBeforeGC) {
479 HandleMark hm; // Discard invalid handles created during verification
480 Universe::verify("Before GC");
481 }
482 COMPILER2_PRESENT(DerivedPointerTable::clear());
483
484 if (restore_marks_for_biased_locking) {
485 // We perform this mark word preservation work lazily
486 // because it's only at this point that we know whether we
487 // absolutely have to do it; we want to avoid doing it for
488 // scavenge-only collections where it's unnecessary
489 BiasedLocking::preserve_marks();
490 }
491
492 // Do collection work
493 {
494 // Note on ref discovery: For what appear to be historical reasons,
495 // GCH enables and disabled (by enqueing) refs discovery.
496 // In the future this should be moved into the generation's
497 // collect method so that ref discovery and enqueueing concerns
498 // are local to a generation. The collect method could return
499 // an appropriate indication in the case that notification on
500 // the ref lock was needed. This will make the treatment of
501 // weak refs more uniform (and indeed remove such concerns
502 // from GCH). XXX
503
504 HandleMark hm; // Discard invalid handles created during gc
505 save_marks(); // save marks for all gens
506 // We want to discover references, but not process them yet.
507 // This mode is disabled in process_discovered_references if the
508 // generation does some collection work, or in
509 // enqueue_discovered_references if the generation returns
510 // without doing any work.
511 ReferenceProcessor* rp = gen->ref_processor();
512 // If the discovery of ("weak") refs in this generation is
513 // atomic wrt other collectors in this configuration, we
514 // are guaranteed to have empty discovered ref lists.
515 if (rp->discovery_is_atomic()) {
516 rp->enable_discovery();
517 rp->setup_policy(clear_soft_refs);
518 } else {
519 // collect() below will enable discovery as appropriate
520 }
521 gen->collect(full, clear_soft_refs, size, is_tlab);
522 if (!rp->enqueuing_is_done()) {
523 rp->disable_discovery();
524 } else {
525 rp->set_enqueuing_is_done(false);
526 }
527 rp->verify_no_references_recorded();
528 }
529
530 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
531
532 gen->stat_record()->accumulated_time.stop();
533
534 update_gc_stats(gen, full);
535
536 if (run_verification && VerifyAfterGC) {
537 HandleMark hm; // Discard invalid handles created during verification
538 Universe::verify("After GC");
539 }
540 }
541
542 void GenCollectedHeap::do_collection(bool full,
543 bool clear_all_soft_refs,
544 size_t size,
545 bool is_tlab,
546 GenerationType max_generation) {
547 ResourceMark rm;
548 DEBUG_ONLY(Thread* my_thread = Thread::current();)
549
550 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
551 assert(my_thread->is_VM_thread() ||
552 my_thread->is_ConcurrentGC_thread(),
553 "incorrect thread type capability");
554 assert(Heap_lock->is_locked(),
555 "the requesting thread should have the Heap_lock");
556 guarantee(!is_gc_active(), "collection is not reentrant");
557
558 if (GCLocker::check_active_before_gc()) {
559 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
560 }
561
562 GCIdMark gc_id_mark;
563
564 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
565 soft_ref_policy()->should_clear_all_soft_refs();
566
567 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
568
569 const size_t metadata_prev_used = MetaspaceUtils::used_bytes();
570
571 print_heap_before_gc();
572
573 {
574 FlagSetting fl(_is_gc_active, true);
575
576 bool complete = full && (max_generation == OldGen);
577 bool old_collects_young = complete && !ScavengeBeforeFullGC;
578 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
579
580 FormatBuffer<> gc_string("%s", "Pause ");
581 if (do_young_collection) {
582 gc_string.append("Young");
583 } else {
584 gc_string.append("Full");
585 }
586
587 GCTraceCPUTime tcpu;
588 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
589
590 gc_prologue(complete);
591 increment_total_collections(complete);
592
593 size_t young_prev_used = _young_gen->used();
594 size_t old_prev_used = _old_gen->used();
595
596 bool run_verification = total_collections() >= VerifyGCStartAt;
597
598 bool prepared_for_verification = false;
599 bool collected_old = false;
600
601 if (do_young_collection) {
602 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
603 prepare_for_verify();
604 prepared_for_verification = true;
605 }
606
607 collect_generation(_young_gen,
608 full,
609 size,
610 is_tlab,
611 run_verification && VerifyGCLevel <= 0,
612 do_clear_all_soft_refs,
613 false);
614
615 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
616 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
617 // Allocation request was met by young GC.
618 size = 0;
619 }
620 }
621
622 bool must_restore_marks_for_biased_locking = false;
623
624 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
625 if (!complete) {
626 // The full_collections increment was missed above.
627 increment_total_full_collections();
628 }
629
630 if (!prepared_for_verification && run_verification &&
631 VerifyGCLevel <= 1 && VerifyBeforeGC) {
632 prepare_for_verify();
633 }
634
635 if (do_young_collection) {
636 // We did a young GC. Need a new GC id for the old GC.
637 GCIdMark gc_id_mark;
638 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
639 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
640 } else {
641 // No young GC done. Use the same GC id as was set up earlier in this method.
642 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
643 }
644
645 must_restore_marks_for_biased_locking = true;
646 collected_old = true;
647 }
648
649 // Update "complete" boolean wrt what actually transpired --
650 // for instance, a promotion failure could have led to
651 // a whole heap collection.
652 complete = complete || collected_old;
653
654 print_heap_change(young_prev_used, old_prev_used);
655 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
656
657 // Adjust generation sizes.
658 if (collected_old) {
659 _old_gen->compute_new_size();
660 }
661 _young_gen->compute_new_size();
662
663 if (complete) {
664 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
665 ClassLoaderDataGraph::purge();
666 MetaspaceUtils::verify_metrics();
667 // Resize the metaspace capacity after full collections
668 MetaspaceGC::compute_new_size();
669 update_full_collections_completed();
670 }
671
672 // Track memory usage and detect low memory after GC finishes
673 MemoryService::track_memory_usage();
674
675 gc_epilogue(complete);
676
677 if (must_restore_marks_for_biased_locking) {
678 BiasedLocking::restore_marks();
679 }
680 }
681
682 print_heap_after_gc();
683
684 #ifdef TRACESPINNING
685 ParallelTaskTerminator::print_termination_counts();
686 #endif
687 }
688
689 void GenCollectedHeap::register_nmethod(nmethod* nm) {
690 CodeCache::register_scavenge_root_nmethod(nm);
691 }
692
693 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
694 CodeCache::verify_scavenge_root_nmethod(nm);
695 }
696
697 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
698 GCCauseSetter x(this, GCCause::_allocation_failure);
699 HeapWord* result = NULL;
700
701 assert(size != 0, "Precondition violated");
702 if (GCLocker::is_active_and_needs_gc()) {
703 // GC locker is active; instead of a collection we will attempt
704 // to expand the heap, if there's room for expansion.
705 if (!is_maximal_no_gc()) {
706 result = expand_heap_and_allocate(size, is_tlab);
707 }
708 return result; // Could be null if we are out of space.
709 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
710 // Do an incremental collection.
711 do_collection(false, // full
712 false, // clear_all_soft_refs
713 size, // size
714 is_tlab, // is_tlab
715 GenCollectedHeap::OldGen); // max_generation
716 } else {
717 log_trace(gc)(" :: Trying full because partial may fail :: ");
718 // Try a full collection; see delta for bug id 6266275
719 // for the original code and why this has been simplified
720 // with from-space allocation criteria modified and
721 // such allocation moved out of the safepoint path.
722 do_collection(true, // full
723 false, // clear_all_soft_refs
724 size, // size
725 is_tlab, // is_tlab
726 GenCollectedHeap::OldGen); // max_generation
727 }
728
729 result = attempt_allocation(size, is_tlab, false /*first_only*/);
730
731 if (result != NULL) {
732 assert(is_in_reserved(result), "result not in heap");
733 return result;
734 }
735
736 // OK, collection failed, try expansion.
737 result = expand_heap_and_allocate(size, is_tlab);
738 if (result != NULL) {
739 return result;
740 }
741
742 // If we reach this point, we're really out of memory. Try every trick
743 // we can to reclaim memory. Force collection of soft references. Force
744 // a complete compaction of the heap. Any additional methods for finding
745 // free memory should be here, especially if they are expensive. If this
746 // attempt fails, an OOM exception will be thrown.
747 {
748 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
749
750 do_collection(true, // full
751 true, // clear_all_soft_refs
752 size, // size
753 is_tlab, // is_tlab
754 GenCollectedHeap::OldGen); // max_generation
755 }
756
757 result = attempt_allocation(size, is_tlab, false /* first_only */);
758 if (result != NULL) {
759 assert(is_in_reserved(result), "result not in heap");
760 return result;
761 }
762
763 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
764 "Flag should have been handled and cleared prior to this point");
765
766 // What else? We might try synchronous finalization later. If the total
767 // space available is large enough for the allocation, then a more
768 // complete compaction phase than we've tried so far might be
769 // appropriate.
770 return NULL;
771 }
772
773 #ifdef ASSERT
774 class AssertNonScavengableClosure: public OopClosure {
775 public:
776 virtual void do_oop(oop* p) {
777 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
778 "Referent should not be scavengable."); }
779 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
780 };
781 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
782 #endif
783
784 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
785 ScanningOption so,
786 OopClosure* strong_roots,
787 OopClosure* weak_roots,
788 CLDClosure* strong_cld_closure,
789 CLDClosure* weak_cld_closure,
790 CodeBlobToOopClosure* code_roots) {
791 // General roots.
792 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
793 assert(code_roots != NULL, "code root closure should always be set");
794 // _n_termination for _process_strong_tasks should be set up stream
795 // in a method not running in a GC worker. Otherwise the GC worker
796 // could be trying to change the termination condition while the task
797 // is executing in another GC worker.
798
799 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
800 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
801 }
802
803 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
804 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
805
806 bool is_par = scope->n_threads() > 1;
807 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
808
809 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
810 Universe::oops_do(strong_roots);
811 }
812 // Global (strong) JNI handles
813 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
814 JNIHandles::oops_do(strong_roots);
815 }
816
817 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
818 ObjectSynchronizer::oops_do(strong_roots);
819 }
820 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
821 Management::oops_do(strong_roots);
822 }
823 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
824 JvmtiExport::oops_do(strong_roots);
825 }
826 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
827 AOTLoader::oops_do(strong_roots);
828 }
829
830 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
831 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
832 }
833
834 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
835 if (so & SO_ScavengeCodeCache) {
836 assert(code_roots != NULL, "must supply closure for code cache");
837
838 // We only visit parts of the CodeCache when scavenging.
839 CodeCache::scavenge_root_nmethods_do(code_roots);
840 }
841 if (so & SO_AllCodeCache) {
842 assert(code_roots != NULL, "must supply closure for code cache");
843
844 // CMSCollector uses this to do intermediate-strength collections.
845 // We scan the entire code cache, since CodeCache::do_unloading is not called.
846 CodeCache::blobs_do(code_roots);
847 }
848 // Verify that the code cache contents are not subject to
849 // movement by a scavenging collection.
850 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
851 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
852 }
853 }
854
855 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
856 OopClosure* root_closure,
857 OopStorage::ParState<false, false>* par_state_string) {
858 assert(root_closure != NULL, "Must be set");
859 // All threads execute the following. A specific chunk of buckets
860 // from the StringTable are the individual tasks.
861
862 // Either we should be single threaded or have a ParState
863 assert((scope->n_threads() <= 1) || par_state_string != NULL, "Parallel but not ParState");
864
865 if (scope->n_threads() > 1 && par_state_string != NULL) {
866 StringTable::possibly_parallel_oops_do(par_state_string, root_closure);
867 } else {
868 StringTable::oops_do(root_closure);
869 }
870 }
871
872 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
873 OopsInGenClosure* root_closure,
874 OopsInGenClosure* old_gen_closure,
875 CLDClosure* cld_closure,
876 OopStorage::ParState<false, false>* par_state_string) {
877 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
878
879 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
880 cld_closure, cld_closure, &mark_code_closure);
881
882 process_string_table_roots(scope, root_closure, par_state_string);
883
884 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
885 root_closure->reset_generation();
886 }
887
888 // When collection is parallel, all threads get to cooperate to do
889 // old generation scanning.
890 old_gen_closure->set_generation(_old_gen);
891 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
892 old_gen_closure->reset_generation();
893
894 _process_strong_tasks->all_tasks_completed(scope->n_threads());
895 }
896
897 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
898 bool is_adjust_phase,
899 ScanningOption so,
900 bool only_strong_roots,
901 OopsInGenClosure* root_closure,
902 CLDClosure* cld_closure,
903 OopStorage::ParState<false, false>* par_state_string) {
904 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
905 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
906 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
907
908 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
909 if (is_adjust_phase) {
910 // We never treat the string table as roots during marking
911 // for the full gc, so we only need to process it during
912 // the adjust phase.
913 process_string_table_roots(scope, root_closure, par_state_string);
914 }
915
916 _process_strong_tasks->all_tasks_completed(scope->n_threads());
917 }
918
919 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
920 WeakProcessor::oops_do(root_closure);
921 _young_gen->ref_processor()->weak_oops_do(root_closure);
922 _old_gen->ref_processor()->weak_oops_do(root_closure);
923 }
924
925 bool GenCollectedHeap::no_allocs_since_save_marks() {
926 return _young_gen->no_allocs_since_save_marks() &&
927 _old_gen->no_allocs_since_save_marks();
928 }
929
930 bool GenCollectedHeap::supports_inline_contig_alloc() const {
931 return _young_gen->supports_inline_contig_alloc();
932 }
933
934 HeapWord* volatile* GenCollectedHeap::top_addr() const {
935 return _young_gen->top_addr();
936 }
937
938 HeapWord** GenCollectedHeap::end_addr() const {
939 return _young_gen->end_addr();
940 }
941
942 // public collection interfaces
943
944 void GenCollectedHeap::collect(GCCause::Cause cause) {
945 if (cause == GCCause::_wb_young_gc) {
946 // Young collection for the WhiteBox API.
947 collect(cause, YoungGen);
948 } else {
949 #ifdef ASSERT
950 if (cause == GCCause::_scavenge_alot) {
951 // Young collection only.
952 collect(cause, YoungGen);
953 } else {
954 // Stop-the-world full collection.
955 collect(cause, OldGen);
956 }
957 #else
958 // Stop-the-world full collection.
959 collect(cause, OldGen);
960 #endif
961 }
962 }
963
964 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
965 // The caller doesn't have the Heap_lock
966 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
967 MutexLocker ml(Heap_lock);
968 collect_locked(cause, max_generation);
969 }
970
971 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
972 // The caller has the Heap_lock
973 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
974 collect_locked(cause, OldGen);
975 }
976
977 // this is the private collection interface
978 // The Heap_lock is expected to be held on entry.
979
980 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
981 // Read the GC count while holding the Heap_lock
982 unsigned int gc_count_before = total_collections();
983 unsigned int full_gc_count_before = total_full_collections();
984 {
985 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
986 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
987 cause, max_generation);
988 VMThread::execute(&op);
989 }
990 }
991
992 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
993 do_full_collection(clear_all_soft_refs, OldGen);
994 }
995
996 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
997 GenerationType last_generation) {
998 GenerationType local_last_generation;
999 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
1000 gc_cause() == GCCause::_gc_locker) {
1001 local_last_generation = YoungGen;
1002 } else {
1003 local_last_generation = last_generation;
1004 }
1005
1006 do_collection(true, // full
1007 clear_all_soft_refs, // clear_all_soft_refs
1008 0, // size
1009 false, // is_tlab
1010 local_last_generation); // last_generation
1011 // Hack XXX FIX ME !!!
1012 // A scavenge may not have been attempted, or may have
1013 // been attempted and failed, because the old gen was too full
1014 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1015 incremental_collection_will_fail(false /* don't consult_young */)) {
1016 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1017 // This time allow the old gen to be collected as well
1018 do_collection(true, // full
1019 clear_all_soft_refs, // clear_all_soft_refs
1020 0, // size
1021 false, // is_tlab
1022 OldGen); // last_generation
1023 }
1024 }
1025
1026 bool GenCollectedHeap::is_in_young(oop p) {
1027 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1028 assert(result == _young_gen->is_in_reserved(p),
1029 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1030 return result;
1031 }
1032
1033 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1034 bool GenCollectedHeap::is_in(const void* p) const {
1035 return _young_gen->is_in(p) || _old_gen->is_in(p);
1036 }
1037
1038 #ifdef ASSERT
1039 // Don't implement this by using is_in_young(). This method is used
1040 // in some cases to check that is_in_young() is correct.
1041 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1042 assert(is_in_reserved(p) || p == NULL,
1043 "Does not work if address is non-null and outside of the heap");
1044 return p < _young_gen->reserved().end() && p != NULL;
1045 }
1046 #endif
1047
1048 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
1049 NoHeaderExtendedOopClosure no_header_cl(cl);
1050 oop_iterate(&no_header_cl);
1051 }
1052
1053 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
1054 _young_gen->oop_iterate(cl);
1055 _old_gen->oop_iterate(cl);
1056 }
1057
1058 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1059 _young_gen->object_iterate(cl);
1060 _old_gen->object_iterate(cl);
1061 }
1062
1063 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1064 _young_gen->safe_object_iterate(cl);
1065 _old_gen->safe_object_iterate(cl);
1066 }
1067
1068 Space* GenCollectedHeap::space_containing(const void* addr) const {
1069 Space* res = _young_gen->space_containing(addr);
1070 if (res != NULL) {
1071 return res;
1072 }
1073 res = _old_gen->space_containing(addr);
1074 assert(res != NULL, "Could not find containing space");
1075 return res;
1076 }
1077
1078 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1079 assert(is_in_reserved(addr), "block_start of address outside of heap");
1080 if (_young_gen->is_in_reserved(addr)) {
1081 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1082 return _young_gen->block_start(addr);
1083 }
1084
1085 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1086 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1087 return _old_gen->block_start(addr);
1088 }
1089
1090 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1091 assert(is_in_reserved(addr), "block_size of address outside of heap");
1092 if (_young_gen->is_in_reserved(addr)) {
1093 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1094 return _young_gen->block_size(addr);
1095 }
1096
1097 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1098 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1099 return _old_gen->block_size(addr);
1100 }
1101
1102 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1103 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1104 assert(block_start(addr) == addr, "addr must be a block start");
1105 if (_young_gen->is_in_reserved(addr)) {
1106 return _young_gen->block_is_obj(addr);
1107 }
1108
1109 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1110 return _old_gen->block_is_obj(addr);
1111 }
1112
1113 bool GenCollectedHeap::supports_tlab_allocation() const {
1114 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1115 return _young_gen->supports_tlab_allocation();
1116 }
1117
1118 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1119 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1120 if (_young_gen->supports_tlab_allocation()) {
1121 return _young_gen->tlab_capacity();
1122 }
1123 return 0;
1124 }
1125
1126 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1127 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1128 if (_young_gen->supports_tlab_allocation()) {
1129 return _young_gen->tlab_used();
1130 }
1131 return 0;
1132 }
1133
1134 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1135 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1136 if (_young_gen->supports_tlab_allocation()) {
1137 return _young_gen->unsafe_max_tlab_alloc();
1138 }
1139 return 0;
1140 }
1141
1142 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size,
1143 size_t requested_size,
1144 size_t* actual_size) {
1145 bool gc_overhead_limit_was_exceeded;
1146 HeapWord* result = mem_allocate_work(requested_size /* size */,
1147 true /* is_tlab */,
1148 &gc_overhead_limit_was_exceeded);
1149 if (result != NULL) {
1150 *actual_size = requested_size;
1151 }
1152
1153 return result;
1154 }
1155
1156 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1157 // from the list headed by "*prev_ptr".
1158 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1159 bool first = true;
1160 size_t min_size = 0; // "first" makes this conceptually infinite.
1161 ScratchBlock **smallest_ptr, *smallest;
1162 ScratchBlock *cur = *prev_ptr;
1163 while (cur) {
1164 assert(*prev_ptr == cur, "just checking");
1165 if (first || cur->num_words < min_size) {
1166 smallest_ptr = prev_ptr;
1167 smallest = cur;
1168 min_size = smallest->num_words;
1169 first = false;
1170 }
1171 prev_ptr = &cur->next;
1172 cur = cur->next;
1173 }
1174 smallest = *smallest_ptr;
1175 *smallest_ptr = smallest->next;
1176 return smallest;
1177 }
1178
1179 // Sort the scratch block list headed by res into decreasing size order,
1180 // and set "res" to the result.
1181 static void sort_scratch_list(ScratchBlock*& list) {
1182 ScratchBlock* sorted = NULL;
1183 ScratchBlock* unsorted = list;
1184 while (unsorted) {
1185 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1186 smallest->next = sorted;
1187 sorted = smallest;
1188 }
1189 list = sorted;
1190 }
1191
1192 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1193 size_t max_alloc_words) {
1194 ScratchBlock* res = NULL;
1195 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1196 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1197 sort_scratch_list(res);
1198 return res;
1199 }
1200
1201 void GenCollectedHeap::release_scratch() {
1202 _young_gen->reset_scratch();
1203 _old_gen->reset_scratch();
1204 }
1205
1206 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1207 void do_generation(Generation* gen) {
1208 gen->prepare_for_verify();
1209 }
1210 };
1211
1212 void GenCollectedHeap::prepare_for_verify() {
1213 ensure_parsability(false); // no need to retire TLABs
1214 GenPrepareForVerifyClosure blk;
1215 generation_iterate(&blk, false);
1216 }
1217
1218 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1219 bool old_to_young) {
1220 if (old_to_young) {
1221 cl->do_generation(_old_gen);
1222 cl->do_generation(_young_gen);
1223 } else {
1224 cl->do_generation(_young_gen);
1225 cl->do_generation(_old_gen);
1226 }
1227 }
1228
1229 bool GenCollectedHeap::is_maximal_no_gc() const {
1230 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1231 }
1232
1233 void GenCollectedHeap::save_marks() {
1234 _young_gen->save_marks();
1235 _old_gen->save_marks();
1236 }
1237
1238 GenCollectedHeap* GenCollectedHeap::heap() {
1239 CollectedHeap* heap = Universe::heap();
1240 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1241 assert(heap->kind() == CollectedHeap::Serial ||
1242 heap->kind() == CollectedHeap::CMS, "Invalid name");
1243 return (GenCollectedHeap*) heap;
1244 }
1245
1246 #if INCLUDE_SERIALGC
1247 void GenCollectedHeap::prepare_for_compaction() {
1248 // Start by compacting into same gen.
1249 CompactPoint cp(_old_gen);
1250 _old_gen->prepare_for_compaction(&cp);
1251 _young_gen->prepare_for_compaction(&cp);
1252 }
1253 #endif // INCLUDE_SERIALGC
1254
1255 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1256 log_debug(gc, verify)("%s", _old_gen->name());
1257 _old_gen->verify();
1258
1259 log_debug(gc, verify)("%s", _old_gen->name());
1260 _young_gen->verify();
1261
1262 log_debug(gc, verify)("RemSet");
1263 rem_set()->verify();
1264 }
1265
1266 void GenCollectedHeap::print_on(outputStream* st) const {
1267 _young_gen->print_on(st);
1268 _old_gen->print_on(st);
1269 MetaspaceUtils::print_on(st);
1270 }
1271
1272 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1273 }
1274
1275 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1276 }
1277
1278 void GenCollectedHeap::print_tracing_info() const {
1279 if (log_is_enabled(Debug, gc, heap, exit)) {
1280 LogStreamHandle(Debug, gc, heap, exit) lsh;
1281 _young_gen->print_summary_info_on(&lsh);
1282 _old_gen->print_summary_info_on(&lsh);
1283 }
1284 }
1285
1286 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1287 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1288 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1289 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1290 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1291 }
1292
1293 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1294 private:
1295 bool _full;
1296 public:
1297 void do_generation(Generation* gen) {
1298 gen->gc_prologue(_full);
1299 }
1300 GenGCPrologueClosure(bool full) : _full(full) {};
1301 };
1302
1303 void GenCollectedHeap::gc_prologue(bool full) {
1304 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1305
1306 // Fill TLAB's and such
1307 CollectedHeap::accumulate_statistics_all_tlabs();
1308 ensure_parsability(true); // retire TLABs
1309
1310 // Walk generations
1311 GenGCPrologueClosure blk(full);
1312 generation_iterate(&blk, false); // not old-to-young.
1313 };
1314
1315 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1316 private:
1317 bool _full;
1318 public:
1319 void do_generation(Generation* gen) {
1320 gen->gc_epilogue(_full);
1321 }
1322 GenGCEpilogueClosure(bool full) : _full(full) {};
1323 };
1324
1325 void GenCollectedHeap::gc_epilogue(bool full) {
1326 #if COMPILER2_OR_JVMCI
1327 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1328 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1329 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1330 #endif // COMPILER2_OR_JVMCI
1331
1332 resize_all_tlabs();
1333
1334 GenGCEpilogueClosure blk(full);
1335 generation_iterate(&blk, false); // not old-to-young.
1336
1337 if (!CleanChunkPoolAsync) {
1338 Chunk::clean_chunk_pool();
1339 }
1340
1341 MetaspaceCounters::update_performance_counters();
1342 CompressedClassSpaceCounters::update_performance_counters();
1343 };
1344
1345 #ifndef PRODUCT
1346 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1347 private:
1348 public:
1349 void do_generation(Generation* gen) {
1350 gen->record_spaces_top();
1351 }
1352 };
1353
1354 void GenCollectedHeap::record_gen_tops_before_GC() {
1355 if (ZapUnusedHeapArea) {
1356 GenGCSaveTopsBeforeGCClosure blk;
1357 generation_iterate(&blk, false); // not old-to-young.
1358 }
1359 }
1360 #endif // not PRODUCT
1361
1362 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1363 public:
1364 void do_generation(Generation* gen) {
1365 gen->ensure_parsability();
1366 }
1367 };
1368
1369 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1370 CollectedHeap::ensure_parsability(retire_tlabs);
1371 GenEnsureParsabilityClosure ep_cl;
1372 generation_iterate(&ep_cl, false);
1373 }
1374
1375 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1376 oop obj,
1377 size_t obj_size) {
1378 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1379 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1380 HeapWord* result = NULL;
1381
1382 result = old_gen->expand_and_allocate(obj_size, false);
1383
1384 if (result != NULL) {
1385 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1386 }
1387 return oop(result);
1388 }
1389
1390 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1391 jlong _time; // in ms
1392 jlong _now; // in ms
1393
1394 public:
1395 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1396
1397 jlong time() { return _time; }
1398
1399 void do_generation(Generation* gen) {
1400 _time = MIN2(_time, gen->time_of_last_gc(_now));
1401 }
1402 };
1403
1404 jlong GenCollectedHeap::millis_since_last_gc() {
1405 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1406 // provided the underlying platform provides such a time source
1407 // (and it is bug free). So we still have to guard against getting
1408 // back a time later than 'now'.
1409 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1410 GenTimeOfLastGCClosure tolgc_cl(now);
1411 // iterate over generations getting the oldest
1412 // time that a generation was collected
1413 generation_iterate(&tolgc_cl, false);
1414
1415 jlong retVal = now - tolgc_cl.time();
1416 if (retVal < 0) {
1417 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1418 ". returning zero instead.", retVal);
1419 return 0;
1420 }
1421 return retVal;
1422 }