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