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/resourceArea.hpp"
53 #include "oops/oop.inline.hpp"
54 #include "runtime/biasedLocking.hpp"
55 #include "runtime/handles.hpp"
56 #include "runtime/handles.inline.hpp"
57 #include "runtime/java.hpp"
58 #include "runtime/vmThread.hpp"
59 #include "services/management.hpp"
60 #include "services/memoryService.hpp"
61 #include "utilities/debug.hpp"
62 #include "utilities/formatBuffer.hpp"
63 #include "utilities/macros.hpp"
64 #include "utilities/stack.inline.hpp"
65 #include "utilities/vmError.hpp"
66
67 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy,
68 Generation::Name young,
69 Generation::Name old,
70 const char* policy_counters_name) :
71 CollectedHeap(),
72 _rem_set(NULL),
73 _young_gen_spec(new GenerationSpec(young,
74 policy->initial_young_size(),
75 policy->max_young_size(),
76 policy->gen_alignment())),
77 _old_gen_spec(new GenerationSpec(old,
78 policy->initial_old_size(),
79 policy->max_old_size(),
80 policy->gen_alignment())),
81 _gen_policy(policy),
82 _soft_ref_gen_policy(),
83 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)),
84 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
85 _full_collections_completed(0) {
86 }
87
88 jint GenCollectedHeap::initialize() {
89 // While there are no constraints in the GC code that HeapWordSize
90 // be any particular value, there are multiple other areas in the
91 // system which believe this to be true (e.g. oop->object_size in some
92 // cases incorrectly returns the size in wordSize units rather than
93 // HeapWordSize).
94 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
95
96 // Allocate space for the heap.
97
98 char* heap_address;
99 ReservedSpace heap_rs;
100
101 size_t heap_alignment = collector_policy()->heap_alignment();
102
103 heap_address = allocate(heap_alignment, &heap_rs);
104
105 if (!heap_rs.is_reserved()) {
106 vm_shutdown_during_initialization(
107 "Could not reserve enough space for object heap");
108 return JNI_ENOMEM;
109 }
110
111 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
112
113 _rem_set = create_rem_set(reserved_region());
114 _rem_set->initialize();
115 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set);
116 bs->initialize();
117 BarrierSet::set_barrier_set(bs);
118
119 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false);
120 _young_gen = _young_gen_spec->init(young_rs, rem_set());
121 heap_rs = heap_rs.last_part(_young_gen_spec->max_size());
122
123 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false);
124 _old_gen = _old_gen_spec->init(old_rs, rem_set());
125 clear_incremental_collection_failed();
126
127 return JNI_OK;
128 }
129
130 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) {
131 return new CardTableRS(reserved_region, false /* scan_concurrently */);
132 }
133
134 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
135 size_t init_promo_size,
136 size_t init_survivor_size) {
137 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
138 _size_policy = new AdaptiveSizePolicy(init_eden_size,
139 init_promo_size,
140 init_survivor_size,
141 max_gc_pause_sec,
142 GCTimeRatio);
143 }
144
145 char* GenCollectedHeap::allocate(size_t alignment,
146 ReservedSpace* heap_rs){
147 // Now figure out the total size.
148 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
149 assert(alignment % pageSize == 0, "Must be");
150
151 // Check for overflow.
152 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size();
153 if (total_reserved < _young_gen_spec->max_size()) {
154 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
155 "the maximum representable size");
156 }
157 assert(total_reserved % alignment == 0,
158 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
159 SIZE_FORMAT, total_reserved, alignment);
160
161 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
162
163 os::trace_page_sizes("Heap",
164 collector_policy()->min_heap_byte_size(),
165 total_reserved,
166 alignment,
167 heap_rs->base(),
168 heap_rs->size());
169
170 return heap_rs->base();
171 }
172
173 void GenCollectedHeap::post_initialize() {
174 CollectedHeap::post_initialize();
175 ref_processing_init();
176 check_gen_kinds();
177 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
178
179 initialize_size_policy(def_new_gen->eden()->capacity(),
180 _old_gen->capacity(),
181 def_new_gen->from()->capacity());
182 }
183
184 void GenCollectedHeap::ref_processing_init() {
185 _young_gen->ref_processor_init();
186 _old_gen->ref_processor_init();
187 }
188
189 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
190 return _young_gen_spec;
191 }
192
193 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
194 return _old_gen_spec;
195 }
196
197 size_t GenCollectedHeap::capacity() const {
198 return _young_gen->capacity() + _old_gen->capacity();
199 }
200
201 size_t GenCollectedHeap::used() const {
202 return _young_gen->used() + _old_gen->used();
203 }
204
205 void GenCollectedHeap::save_used_regions() {
206 _old_gen->save_used_region();
207 _young_gen->save_used_region();
208 }
209
210 size_t GenCollectedHeap::max_capacity() const {
211 return _young_gen->max_capacity() + _old_gen->max_capacity();
212 }
213
214 // Update the _full_collections_completed counter
215 // at the end of a stop-world full GC.
216 unsigned int GenCollectedHeap::update_full_collections_completed() {
217 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
218 assert(_full_collections_completed <= _total_full_collections,
219 "Can't complete more collections than were started");
220 _full_collections_completed = _total_full_collections;
221 ml.notify_all();
222 return _full_collections_completed;
223 }
224
225 // Update the _full_collections_completed counter, as appropriate,
226 // at the end of a concurrent GC cycle. Note the conditional update
227 // below to allow this method to be called by a concurrent collector
228 // without synchronizing in any manner with the VM thread (which
229 // may already have initiated a STW full collection "concurrently").
230 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
231 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
232 assert((_full_collections_completed <= _total_full_collections) &&
233 (count <= _total_full_collections),
234 "Can't complete more collections than were started");
235 if (count > _full_collections_completed) {
236 _full_collections_completed = count;
237 ml.notify_all();
238 }
239 return _full_collections_completed;
240 }
241
242 // Return true if any of the following is true:
243 // . the allocation won't fit into the current young gen heap
244 // . gc locker is occupied (jni critical section)
245 // . heap memory is tight -- the most recent previous collection
246 // was a full collection because a partial collection (would
247 // have) failed and is likely to fail again
248 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
249 size_t young_capacity = young_gen()->capacity_before_gc();
250 return (word_size > heap_word_size(young_capacity))
251 || GCLocker::is_active_and_needs_gc()
252 || incremental_collection_failed();
253 }
254
255 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
256 HeapWord* result = NULL;
257 if (old_gen()->should_allocate(size, is_tlab)) {
258 result = old_gen()->expand_and_allocate(size, is_tlab);
259 }
260 if (result == NULL) {
261 if (young_gen()->should_allocate(size, is_tlab)) {
262 result = young_gen()->expand_and_allocate(size, is_tlab);
263 }
264 }
265 assert(result == NULL || is_in_reserved(result), "result not in heap");
266 return result;
267 }
268
269 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
270 bool is_tlab,
271 bool* gc_overhead_limit_was_exceeded) {
272 debug_only(check_for_valid_allocation_state());
273 assert(no_gc_in_progress(), "Allocation during gc not allowed");
274
275 // In general gc_overhead_limit_was_exceeded should be false so
276 // set it so here and reset it to true only if the gc time
277 // limit is being exceeded as checked below.
278 *gc_overhead_limit_was_exceeded = false;
279
280 HeapWord* result = NULL;
281
282 // Loop until the allocation is satisfied, or unsatisfied after GC.
283 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
284 HandleMark hm; // Discard any handles allocated in each iteration.
285
286 // First allocation attempt is lock-free.
287 Generation *young = young_gen();
288 assert(young->supports_inline_contig_alloc(),
289 "Otherwise, must do alloc within heap lock");
290 if (young->should_allocate(size, is_tlab)) {
291 result = young->par_allocate(size, is_tlab);
292 if (result != NULL) {
293 assert(is_in_reserved(result), "result not in heap");
294 return result;
295 }
296 }
297 uint gc_count_before; // Read inside the Heap_lock locked region.
298 {
299 MutexLocker ml(Heap_lock);
300 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
301 // Note that only large objects get a shot at being
302 // allocated in later generations.
303 bool first_only = !should_try_older_generation_allocation(size);
304
305 result = attempt_allocation(size, is_tlab, first_only);
306 if (result != NULL) {
307 assert(is_in_reserved(result), "result not in heap");
308 return result;
309 }
310
311 if (GCLocker::is_active_and_needs_gc()) {
312 if (is_tlab) {
313 return NULL; // Caller will retry allocating individual object.
314 }
315 if (!is_maximal_no_gc()) {
316 // Try and expand heap to satisfy request.
317 result = expand_heap_and_allocate(size, is_tlab);
318 // Result could be null if we are out of space.
319 if (result != NULL) {
320 return result;
321 }
322 }
323
324 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
325 return NULL; // We didn't get to do a GC and we didn't get any memory.
326 }
327
328 // If this thread is not in a jni critical section, we stall
329 // the requestor until the critical section has cleared and
330 // GC allowed. When the critical section clears, a GC is
331 // initiated by the last thread exiting the critical section; so
332 // we retry the allocation sequence from the beginning of the loop,
333 // rather than causing more, now probably unnecessary, GC attempts.
334 JavaThread* jthr = JavaThread::current();
335 if (!jthr->in_critical()) {
336 MutexUnlocker mul(Heap_lock);
337 // Wait for JNI critical section to be exited
338 GCLocker::stall_until_clear();
339 gclocker_stalled_count += 1;
340 continue;
341 } else {
342 if (CheckJNICalls) {
343 fatal("Possible deadlock due to allocating while"
344 " in jni critical section");
345 }
346 return NULL;
347 }
348 }
349
350 // Read the gc count while the heap lock is held.
351 gc_count_before = total_collections();
352 }
353
354 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
355 VMThread::execute(&op);
356 if (op.prologue_succeeded()) {
357 result = op.result();
358 if (op.gc_locked()) {
359 assert(result == NULL, "must be NULL if gc_locked() is true");
360 continue; // Retry and/or stall as necessary.
361 }
362
363 // Allocation has failed and a collection
364 // has been done. If the gc time limit was exceeded the
365 // this time, return NULL so that an out-of-memory
366 // will be thrown. Clear gc_overhead_limit_exceeded
367 // so that the overhead exceeded does not persist.
368
369 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
370 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
371
372 if (limit_exceeded && softrefs_clear) {
373 *gc_overhead_limit_was_exceeded = true;
374 size_policy()->set_gc_overhead_limit_exceeded(false);
375 if (op.result() != NULL) {
376 CollectedHeap::fill_with_object(op.result(), size);
377 }
378 return NULL;
379 }
380 assert(result == NULL || is_in_reserved(result),
381 "result not in heap");
382 return result;
383 }
384
385 // Give a warning if we seem to be looping forever.
386 if ((QueuedAllocationWarningCount > 0) &&
387 (try_count % QueuedAllocationWarningCount == 0)) {
388 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
389 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
390 }
391 }
392 }
393
394 #ifndef PRODUCT
395 // Override of memory state checking method in CollectedHeap:
396 // Some collectors (CMS for example) can't have badHeapWordVal written
397 // in the first two words of an object. (For instance , in the case of
398 // CMS these words hold state used to synchronize between certain
399 // (concurrent) GC steps and direct allocating mutators.)
400 // The skip_header_HeapWords() method below, allows us to skip
401 // over the requisite number of HeapWord's. Note that (for
402 // generational collectors) this means that those many words are
403 // skipped in each object, irrespective of the generation in which
404 // that object lives. The resultant loss of precision seems to be
405 // harmless and the pain of avoiding that imprecision appears somewhat
406 // higher than we are prepared to pay for such rudimentary debugging
407 // support.
408 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
409 size_t size) {
410 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
411 // We are asked to check a size in HeapWords,
412 // but the memory is mangled in juint words.
413 juint* start = (juint*) (addr + skip_header_HeapWords());
414 juint* end = (juint*) (addr + size);
415 for (juint* slot = start; slot < end; slot += 1) {
416 assert(*slot == badHeapWordVal,
417 "Found non badHeapWordValue in pre-allocation check");
418 }
419 }
420 }
421 #endif
422
423 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
424 bool is_tlab,
425 bool first_only) {
426 HeapWord* res = NULL;
427
428 if (_young_gen->should_allocate(size, is_tlab)) {
429 res = _young_gen->allocate(size, is_tlab);
430 if (res != NULL || first_only) {
431 return res;
432 }
433 }
434
435 if (_old_gen->should_allocate(size, is_tlab)) {
436 res = _old_gen->allocate(size, is_tlab);
437 }
438
439 return res;
440 }
441
442 HeapWord* GenCollectedHeap::mem_allocate(size_t size, Klass* klass, Thread* thread,
443 bool* gc_overhead_limit_was_exceeded) {
444
445 HeapWord* obj = allocate_from_tlab(klass, thread, size);
446 if (obj != NULL) {
447 return obj;
448 }
449
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 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q());
524 rp->enqueue_discovered_references(NULL, &pt);
525 pt.print_enqueue_phase();
526 } else {
527 rp->set_enqueuing_is_done(false);
528 }
529 rp->verify_no_references_recorded();
530 }
531
532 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
533
534 gen->stat_record()->accumulated_time.stop();
535
536 update_gc_stats(gen, full);
537
538 if (run_verification && VerifyAfterGC) {
539 HandleMark hm; // Discard invalid handles created during verification
540 Universe::verify("After GC");
541 }
542 }
543
544 void GenCollectedHeap::do_collection(bool full,
545 bool clear_all_soft_refs,
546 size_t size,
547 bool is_tlab,
548 GenerationType max_generation) {
549 ResourceMark rm;
550 DEBUG_ONLY(Thread* my_thread = Thread::current();)
551
552 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
553 assert(my_thread->is_VM_thread() ||
554 my_thread->is_ConcurrentGC_thread(),
555 "incorrect thread type capability");
556 assert(Heap_lock->is_locked(),
557 "the requesting thread should have the Heap_lock");
558 guarantee(!is_gc_active(), "collection is not reentrant");
559
560 if (GCLocker::check_active_before_gc()) {
561 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
562 }
563
564 GCIdMark gc_id_mark;
565
566 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
567 soft_ref_policy()->should_clear_all_soft_refs();
568
569 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
570
571 const size_t metadata_prev_used = MetaspaceUtils::used_bytes();
572
573 print_heap_before_gc();
574
575 {
576 FlagSetting fl(_is_gc_active, true);
577
578 bool complete = full && (max_generation == OldGen);
579 bool old_collects_young = complete && !ScavengeBeforeFullGC;
580 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
581
582 FormatBuffer<> gc_string("%s", "Pause ");
583 if (do_young_collection) {
584 gc_string.append("Young");
585 } else {
586 gc_string.append("Full");
587 }
588
589 GCTraceCPUTime tcpu;
590 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
591
592 gc_prologue(complete);
593 increment_total_collections(complete);
594
595 size_t young_prev_used = _young_gen->used();
596 size_t old_prev_used = _old_gen->used();
597
598 bool run_verification = total_collections() >= VerifyGCStartAt;
599
600 bool prepared_for_verification = false;
601 bool collected_old = false;
602
603 if (do_young_collection) {
604 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
605 prepare_for_verify();
606 prepared_for_verification = true;
607 }
608
609 collect_generation(_young_gen,
610 full,
611 size,
612 is_tlab,
613 run_verification && VerifyGCLevel <= 0,
614 do_clear_all_soft_refs,
615 false);
616
617 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
618 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
619 // Allocation request was met by young GC.
620 size = 0;
621 }
622 }
623
624 bool must_restore_marks_for_biased_locking = false;
625
626 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
627 if (!complete) {
628 // The full_collections increment was missed above.
629 increment_total_full_collections();
630 }
631
632 if (!prepared_for_verification && run_verification &&
633 VerifyGCLevel <= 1 && VerifyBeforeGC) {
634 prepare_for_verify();
635 }
636
637 if (do_young_collection) {
638 // We did a young GC. Need a new GC id for the old GC.
639 GCIdMark gc_id_mark;
640 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
641 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
642 } else {
643 // No young GC done. Use the same GC id as was set up earlier in this method.
644 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
645 }
646
647 must_restore_marks_for_biased_locking = true;
648 collected_old = true;
649 }
650
651 // Update "complete" boolean wrt what actually transpired --
652 // for instance, a promotion failure could have led to
653 // a whole heap collection.
654 complete = complete || collected_old;
655
656 print_heap_change(young_prev_used, old_prev_used);
657 MetaspaceUtils::print_metaspace_change(metadata_prev_used);
658
659 // Adjust generation sizes.
660 if (collected_old) {
661 _old_gen->compute_new_size();
662 }
663 _young_gen->compute_new_size();
664
665 if (complete) {
666 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
667 ClassLoaderDataGraph::purge();
668 MetaspaceUtils::verify_metrics();
669 // Resize the metaspace capacity after full collections
670 MetaspaceGC::compute_new_size();
671 update_full_collections_completed();
672 }
673
674 // Track memory usage and detect low memory after GC finishes
675 MemoryService::track_memory_usage();
676
677 gc_epilogue(complete);
678
679 if (must_restore_marks_for_biased_locking) {
680 BiasedLocking::restore_marks();
681 }
682 }
683
684 print_heap_after_gc();
685
686 #ifdef TRACESPINNING
687 ParallelTaskTerminator::print_termination_counts();
688 #endif
689 }
690
691 void GenCollectedHeap::register_nmethod(nmethod* nm) {
692 CodeCache::register_scavenge_root_nmethod(nm);
693 }
694
695 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
696 CodeCache::verify_scavenge_root_nmethod(nm);
697 }
698
699 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
700 GCCauseSetter x(this, GCCause::_allocation_failure);
701 HeapWord* result = NULL;
702
703 assert(size != 0, "Precondition violated");
704 if (GCLocker::is_active_and_needs_gc()) {
705 // GC locker is active; instead of a collection we will attempt
706 // to expand the heap, if there's room for expansion.
707 if (!is_maximal_no_gc()) {
708 result = expand_heap_and_allocate(size, is_tlab);
709 }
710 return result; // Could be null if we are out of space.
711 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
712 // Do an incremental collection.
713 do_collection(false, // full
714 false, // clear_all_soft_refs
715 size, // size
716 is_tlab, // is_tlab
717 GenCollectedHeap::OldGen); // max_generation
718 } else {
719 log_trace(gc)(" :: Trying full because partial may fail :: ");
720 // Try a full collection; see delta for bug id 6266275
721 // for the original code and why this has been simplified
722 // with from-space allocation criteria modified and
723 // such allocation moved out of the safepoint path.
724 do_collection(true, // full
725 false, // clear_all_soft_refs
726 size, // size
727 is_tlab, // is_tlab
728 GenCollectedHeap::OldGen); // max_generation
729 }
730
731 result = attempt_allocation(size, is_tlab, false /*first_only*/);
732
733 if (result != NULL) {
734 assert(is_in_reserved(result), "result not in heap");
735 return result;
736 }
737
738 // OK, collection failed, try expansion.
739 result = expand_heap_and_allocate(size, is_tlab);
740 if (result != NULL) {
741 return result;
742 }
743
744 // If we reach this point, we're really out of memory. Try every trick
745 // we can to reclaim memory. Force collection of soft references. Force
746 // a complete compaction of the heap. Any additional methods for finding
747 // free memory should be here, especially if they are expensive. If this
748 // attempt fails, an OOM exception will be thrown.
749 {
750 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
751
752 do_collection(true, // full
753 true, // clear_all_soft_refs
754 size, // size
755 is_tlab, // is_tlab
756 GenCollectedHeap::OldGen); // max_generation
757 }
758
759 result = attempt_allocation(size, is_tlab, false /* first_only */);
760 if (result != NULL) {
761 assert(is_in_reserved(result), "result not in heap");
762 return result;
763 }
764
765 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
766 "Flag should have been handled and cleared prior to this point");
767
768 // What else? We might try synchronous finalization later. If the total
769 // space available is large enough for the allocation, then a more
770 // complete compaction phase than we've tried so far might be
771 // appropriate.
772 return NULL;
773 }
774
775 #ifdef ASSERT
776 class AssertNonScavengableClosure: public OopClosure {
777 public:
778 virtual void do_oop(oop* p) {
779 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
780 "Referent should not be scavengable."); }
781 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
782 };
783 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
784 #endif
785
786 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
787 ScanningOption so,
788 OopClosure* strong_roots,
789 OopClosure* weak_roots,
790 CLDClosure* strong_cld_closure,
791 CLDClosure* weak_cld_closure,
792 CodeBlobToOopClosure* code_roots) {
793 // General roots.
794 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
795 assert(code_roots != NULL, "code root closure should always be set");
796 // _n_termination for _process_strong_tasks should be set up stream
797 // in a method not running in a GC worker. Otherwise the GC worker
798 // could be trying to change the termination condition while the task
799 // is executing in another GC worker.
800
801 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
802 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
803 }
804
805 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
806 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
807
808 bool is_par = scope->n_threads() > 1;
809 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
810
811 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
812 Universe::oops_do(strong_roots);
813 }
814 // Global (strong) JNI handles
815 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
816 JNIHandles::oops_do(strong_roots);
817 }
818
819 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
820 ObjectSynchronizer::oops_do(strong_roots);
821 }
822 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
823 Management::oops_do(strong_roots);
824 }
825 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
826 JvmtiExport::oops_do(strong_roots);
827 }
828 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
829 AOTLoader::oops_do(strong_roots);
830 }
831
832 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
833 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
834 }
835
836 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
837 if (so & SO_ScavengeCodeCache) {
838 assert(code_roots != NULL, "must supply closure for code cache");
839
840 // We only visit parts of the CodeCache when scavenging.
841 CodeCache::scavenge_root_nmethods_do(code_roots);
842 }
843 if (so & SO_AllCodeCache) {
844 assert(code_roots != NULL, "must supply closure for code cache");
845
846 // CMSCollector uses this to do intermediate-strength collections.
847 // We scan the entire code cache, since CodeCache::do_unloading is not called.
848 CodeCache::blobs_do(code_roots);
849 }
850 // Verify that the code cache contents are not subject to
851 // movement by a scavenging collection.
852 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
853 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
854 }
855 }
856
857 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
858 OopClosure* root_closure) {
859 assert(root_closure != NULL, "Must be set");
860 // All threads execute the following. A specific chunk of buckets
861 // from the StringTable are the individual tasks.
862 if (scope->n_threads() > 1) {
863 StringTable::possibly_parallel_oops_do(root_closure);
864 } else {
865 StringTable::oops_do(root_closure);
866 }
867 }
868
869 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
870 OopsInGenClosure* root_closure,
871 OopsInGenClosure* old_gen_closure,
872 CLDClosure* cld_closure) {
873 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
874
875 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
876 cld_closure, cld_closure, &mark_code_closure);
877 process_string_table_roots(scope, root_closure);
878
879 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
880 root_closure->reset_generation();
881 }
882
883 // When collection is parallel, all threads get to cooperate to do
884 // old generation scanning.
885 old_gen_closure->set_generation(_old_gen);
886 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
887 old_gen_closure->reset_generation();
888
889 _process_strong_tasks->all_tasks_completed(scope->n_threads());
890 }
891
892 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
893 bool is_adjust_phase,
894 ScanningOption so,
895 bool only_strong_roots,
896 OopsInGenClosure* root_closure,
897 CLDClosure* cld_closure) {
898 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
899 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
900 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
901
902 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
903 if (is_adjust_phase) {
904 // We never treat the string table as roots during marking
905 // for the full gc, so we only need to process it during
906 // the adjust phase.
907 process_string_table_roots(scope, root_closure);
908 }
909
910 _process_strong_tasks->all_tasks_completed(scope->n_threads());
911 }
912
913 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
914 WeakProcessor::oops_do(root_closure);
915 _young_gen->ref_processor()->weak_oops_do(root_closure);
916 _old_gen->ref_processor()->weak_oops_do(root_closure);
917 }
918
919 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
920 void GenCollectedHeap:: \
921 oop_since_save_marks_iterate(GenerationType gen, \
922 OopClosureType* cur, \
923 OopClosureType* older) { \
924 if (gen == YoungGen) { \
925 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
926 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
927 } else { \
928 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
929 } \
930 }
931
932 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
933
934 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
935
936 bool GenCollectedHeap::no_allocs_since_save_marks() {
937 return _young_gen->no_allocs_since_save_marks() &&
938 _old_gen->no_allocs_since_save_marks();
939 }
940
941 bool GenCollectedHeap::supports_inline_contig_alloc() const {
942 return _young_gen->supports_inline_contig_alloc();
943 }
944
945 HeapWord* volatile* GenCollectedHeap::top_addr() const {
946 return _young_gen->top_addr();
947 }
948
949 HeapWord** GenCollectedHeap::end_addr() const {
950 return _young_gen->end_addr();
951 }
952
953 // public collection interfaces
954
955 void GenCollectedHeap::collect(GCCause::Cause cause) {
956 if (cause == GCCause::_wb_young_gc) {
957 // Young collection for the WhiteBox API.
958 collect(cause, YoungGen);
959 } else {
960 #ifdef ASSERT
961 if (cause == GCCause::_scavenge_alot) {
962 // Young collection only.
963 collect(cause, YoungGen);
964 } else {
965 // Stop-the-world full collection.
966 collect(cause, OldGen);
967 }
968 #else
969 // Stop-the-world full collection.
970 collect(cause, OldGen);
971 #endif
972 }
973 }
974
975 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
976 // The caller doesn't have the Heap_lock
977 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
978 MutexLocker ml(Heap_lock);
979 collect_locked(cause, max_generation);
980 }
981
982 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
983 // The caller has the Heap_lock
984 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
985 collect_locked(cause, OldGen);
986 }
987
988 // this is the private collection interface
989 // The Heap_lock is expected to be held on entry.
990
991 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
992 // Read the GC count while holding the Heap_lock
993 unsigned int gc_count_before = total_collections();
994 unsigned int full_gc_count_before = total_full_collections();
995 {
996 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
997 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
998 cause, max_generation);
999 VMThread::execute(&op);
1000 }
1001 }
1002
1003 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
1004 do_full_collection(clear_all_soft_refs, OldGen);
1005 }
1006
1007 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
1008 GenerationType last_generation) {
1009 GenerationType local_last_generation;
1010 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
1011 gc_cause() == GCCause::_gc_locker) {
1012 local_last_generation = YoungGen;
1013 } else {
1014 local_last_generation = last_generation;
1015 }
1016
1017 do_collection(true, // full
1018 clear_all_soft_refs, // clear_all_soft_refs
1019 0, // size
1020 false, // is_tlab
1021 local_last_generation); // last_generation
1022 // Hack XXX FIX ME !!!
1023 // A scavenge may not have been attempted, or may have
1024 // been attempted and failed, because the old gen was too full
1025 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1026 incremental_collection_will_fail(false /* don't consult_young */)) {
1027 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1028 // This time allow the old gen to be collected as well
1029 do_collection(true, // full
1030 clear_all_soft_refs, // clear_all_soft_refs
1031 0, // size
1032 false, // is_tlab
1033 OldGen); // last_generation
1034 }
1035 }
1036
1037 bool GenCollectedHeap::is_in_young(oop p) {
1038 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1039 assert(result == _young_gen->is_in_reserved(p),
1040 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1041 return result;
1042 }
1043
1044 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1045 bool GenCollectedHeap::is_in(const void* p) const {
1046 return _young_gen->is_in(p) || _old_gen->is_in(p);
1047 }
1048
1049 #ifdef ASSERT
1050 // Don't implement this by using is_in_young(). This method is used
1051 // in some cases to check that is_in_young() is correct.
1052 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1053 assert(is_in_reserved(p) || p == NULL,
1054 "Does not work if address is non-null and outside of the heap");
1055 return p < _young_gen->reserved().end() && p != NULL;
1056 }
1057 #endif
1058
1059 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
1060 NoHeaderExtendedOopClosure no_header_cl(cl);
1061 oop_iterate(&no_header_cl);
1062 }
1063
1064 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
1065 _young_gen->oop_iterate(cl);
1066 _old_gen->oop_iterate(cl);
1067 }
1068
1069 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1070 _young_gen->object_iterate(cl);
1071 _old_gen->object_iterate(cl);
1072 }
1073
1074 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1075 _young_gen->safe_object_iterate(cl);
1076 _old_gen->safe_object_iterate(cl);
1077 }
1078
1079 Space* GenCollectedHeap::space_containing(const void* addr) const {
1080 Space* res = _young_gen->space_containing(addr);
1081 if (res != NULL) {
1082 return res;
1083 }
1084 res = _old_gen->space_containing(addr);
1085 assert(res != NULL, "Could not find containing space");
1086 return res;
1087 }
1088
1089 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1090 assert(is_in_reserved(addr), "block_start of address outside of heap");
1091 if (_young_gen->is_in_reserved(addr)) {
1092 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1093 return _young_gen->block_start(addr);
1094 }
1095
1096 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1097 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1098 return _old_gen->block_start(addr);
1099 }
1100
1101 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1102 assert(is_in_reserved(addr), "block_size of address outside of heap");
1103 if (_young_gen->is_in_reserved(addr)) {
1104 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1105 return _young_gen->block_size(addr);
1106 }
1107
1108 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1109 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1110 return _old_gen->block_size(addr);
1111 }
1112
1113 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1114 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1115 assert(block_start(addr) == addr, "addr must be a block start");
1116 if (_young_gen->is_in_reserved(addr)) {
1117 return _young_gen->block_is_obj(addr);
1118 }
1119
1120 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1121 return _old_gen->block_is_obj(addr);
1122 }
1123
1124 bool GenCollectedHeap::supports_tlab_allocation() const {
1125 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1126 return _young_gen->supports_tlab_allocation();
1127 }
1128
1129 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1130 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1131 if (_young_gen->supports_tlab_allocation()) {
1132 return _young_gen->tlab_capacity();
1133 }
1134 return 0;
1135 }
1136
1137 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1138 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1139 if (_young_gen->supports_tlab_allocation()) {
1140 return _young_gen->tlab_used();
1141 }
1142 return 0;
1143 }
1144
1145 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1146 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1147 if (_young_gen->supports_tlab_allocation()) {
1148 return _young_gen->unsafe_max_tlab_alloc();
1149 }
1150 return 0;
1151 }
1152
1153 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1154 bool gc_overhead_limit_was_exceeded;
1155 return mem_allocate_work(size /* size */,
1156 true /* is_tlab */,
1157 &gc_overhead_limit_was_exceeded);
1158 }
1159
1160 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1161 // from the list headed by "*prev_ptr".
1162 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1163 bool first = true;
1164 size_t min_size = 0; // "first" makes this conceptually infinite.
1165 ScratchBlock **smallest_ptr, *smallest;
1166 ScratchBlock *cur = *prev_ptr;
1167 while (cur) {
1168 assert(*prev_ptr == cur, "just checking");
1169 if (first || cur->num_words < min_size) {
1170 smallest_ptr = prev_ptr;
1171 smallest = cur;
1172 min_size = smallest->num_words;
1173 first = false;
1174 }
1175 prev_ptr = &cur->next;
1176 cur = cur->next;
1177 }
1178 smallest = *smallest_ptr;
1179 *smallest_ptr = smallest->next;
1180 return smallest;
1181 }
1182
1183 // Sort the scratch block list headed by res into decreasing size order,
1184 // and set "res" to the result.
1185 static void sort_scratch_list(ScratchBlock*& list) {
1186 ScratchBlock* sorted = NULL;
1187 ScratchBlock* unsorted = list;
1188 while (unsorted) {
1189 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1190 smallest->next = sorted;
1191 sorted = smallest;
1192 }
1193 list = sorted;
1194 }
1195
1196 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1197 size_t max_alloc_words) {
1198 ScratchBlock* res = NULL;
1199 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1200 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1201 sort_scratch_list(res);
1202 return res;
1203 }
1204
1205 void GenCollectedHeap::release_scratch() {
1206 _young_gen->reset_scratch();
1207 _old_gen->reset_scratch();
1208 }
1209
1210 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1211 void do_generation(Generation* gen) {
1212 gen->prepare_for_verify();
1213 }
1214 };
1215
1216 void GenCollectedHeap::prepare_for_verify() {
1217 ensure_parsability(false); // no need to retire TLABs
1218 GenPrepareForVerifyClosure blk;
1219 generation_iterate(&blk, false);
1220 }
1221
1222 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1223 bool old_to_young) {
1224 if (old_to_young) {
1225 cl->do_generation(_old_gen);
1226 cl->do_generation(_young_gen);
1227 } else {
1228 cl->do_generation(_young_gen);
1229 cl->do_generation(_old_gen);
1230 }
1231 }
1232
1233 bool GenCollectedHeap::is_maximal_no_gc() const {
1234 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1235 }
1236
1237 void GenCollectedHeap::save_marks() {
1238 _young_gen->save_marks();
1239 _old_gen->save_marks();
1240 }
1241
1242 GenCollectedHeap* GenCollectedHeap::heap() {
1243 CollectedHeap* heap = Universe::heap();
1244 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1245 assert(heap->kind() == CollectedHeap::Serial ||
1246 heap->kind() == CollectedHeap::CMS, "Invalid name");
1247 return (GenCollectedHeap*) heap;
1248 }
1249
1250 void GenCollectedHeap::prepare_for_compaction() {
1251 // Start by compacting into same gen.
1252 CompactPoint cp(_old_gen);
1253 _old_gen->prepare_for_compaction(&cp);
1254 _young_gen->prepare_for_compaction(&cp);
1255 }
1256
1257 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1258 log_debug(gc, verify)("%s", _old_gen->name());
1259 _old_gen->verify();
1260
1261 log_debug(gc, verify)("%s", _old_gen->name());
1262 _young_gen->verify();
1263
1264 log_debug(gc, verify)("RemSet");
1265 rem_set()->verify();
1266 }
1267
1268 void GenCollectedHeap::print_on(outputStream* st) const {
1269 _young_gen->print_on(st);
1270 _old_gen->print_on(st);
1271 MetaspaceUtils::print_on(st);
1272 }
1273
1274 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1275 }
1276
1277 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1278 }
1279
1280 void GenCollectedHeap::print_tracing_info() const {
1281 if (log_is_enabled(Debug, gc, heap, exit)) {
1282 LogStreamHandle(Debug, gc, heap, exit) lsh;
1283 _young_gen->print_summary_info_on(&lsh);
1284 _old_gen->print_summary_info_on(&lsh);
1285 }
1286 }
1287
1288 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1289 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1290 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1291 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1292 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1293 }
1294
1295 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1296 private:
1297 bool _full;
1298 public:
1299 void do_generation(Generation* gen) {
1300 gen->gc_prologue(_full);
1301 }
1302 GenGCPrologueClosure(bool full) : _full(full) {};
1303 };
1304
1305 void GenCollectedHeap::gc_prologue(bool full) {
1306 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1307
1308 // Fill TLAB's and such
1309 CollectedHeap::accumulate_statistics_all_tlabs();
1310 ensure_parsability(true); // retire TLABs
1311
1312 // Walk generations
1313 GenGCPrologueClosure blk(full);
1314 generation_iterate(&blk, false); // not old-to-young.
1315 };
1316
1317 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1318 private:
1319 bool _full;
1320 public:
1321 void do_generation(Generation* gen) {
1322 gen->gc_epilogue(_full);
1323 }
1324 GenGCEpilogueClosure(bool full) : _full(full) {};
1325 };
1326
1327 void GenCollectedHeap::gc_epilogue(bool full) {
1328 #if COMPILER2_OR_JVMCI
1329 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1330 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1331 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1332 #endif // COMPILER2_OR_JVMCI
1333
1334 resize_all_tlabs();
1335
1336 GenGCEpilogueClosure blk(full);
1337 generation_iterate(&blk, false); // not old-to-young.
1338
1339 if (!CleanChunkPoolAsync) {
1340 Chunk::clean_chunk_pool();
1341 }
1342
1343 MetaspaceCounters::update_performance_counters();
1344 CompressedClassSpaceCounters::update_performance_counters();
1345 };
1346
1347 #ifndef PRODUCT
1348 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1349 private:
1350 public:
1351 void do_generation(Generation* gen) {
1352 gen->record_spaces_top();
1353 }
1354 };
1355
1356 void GenCollectedHeap::record_gen_tops_before_GC() {
1357 if (ZapUnusedHeapArea) {
1358 GenGCSaveTopsBeforeGCClosure blk;
1359 generation_iterate(&blk, false); // not old-to-young.
1360 }
1361 }
1362 #endif // not PRODUCT
1363
1364 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1365 public:
1366 void do_generation(Generation* gen) {
1367 gen->ensure_parsability();
1368 }
1369 };
1370
1371 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1372 CollectedHeap::ensure_parsability(retire_tlabs);
1373 GenEnsureParsabilityClosure ep_cl;
1374 generation_iterate(&ep_cl, false);
1375 }
1376
1377 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1378 oop obj,
1379 size_t obj_size) {
1380 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1381 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1382 HeapWord* result = NULL;
1383
1384 result = old_gen->expand_and_allocate(obj_size, false);
1385
1386 if (result != NULL) {
1387 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1388 }
1389 return oop(result);
1390 }
1391
1392 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1393 jlong _time; // in ms
1394 jlong _now; // in ms
1395
1396 public:
1397 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1398
1399 jlong time() { return _time; }
1400
1401 void do_generation(Generation* gen) {
1402 _time = MIN2(_time, gen->time_of_last_gc(_now));
1403 }
1404 };
1405
1406 jlong GenCollectedHeap::millis_since_last_gc() {
1407 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1408 // provided the underlying platform provides such a time source
1409 // (and it is bug free). So we still have to guard against getting
1410 // back a time later than 'now'.
1411 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1412 GenTimeOfLastGCClosure tolgc_cl(now);
1413 // iterate over generations getting the oldest
1414 // time that a generation was collected
1415 generation_iterate(&tolgc_cl, false);
1416
1417 jlong retVal = now - tolgc_cl.time();
1418 if (retVal < 0) {
1419 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1420 ". returning zero instead.", retVal);
1421 return 0;
1422 }
1423 return retVal;
1424 }