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