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