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