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_generations(Generation::Name young,
124 Generation::Name old) {
125 }
126
127 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size,
128 size_t init_promo_size,
129 size_t init_survivor_size) {
130 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0;
131 _size_policy = new AdaptiveSizePolicy(init_eden_size,
132 init_promo_size,
133 init_survivor_size,
134 max_gc_pause_sec,
135 GCTimeRatio);
136 }
137
138 char* GenCollectedHeap::allocate(size_t alignment,
139 ReservedSpace* heap_rs){
140 // Now figure out the total size.
141 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
142 assert(alignment % pageSize == 0, "Must be");
143
144 GenerationSpec* young_spec = young_gen_spec();
145 GenerationSpec* old_spec = old_gen_spec();
146
147 // Check for overflow.
148 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
149 if (total_reserved < young_spec->max_size()) {
150 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
151 "the maximum representable size");
152 }
153 assert(total_reserved % alignment == 0,
154 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
155 SIZE_FORMAT, total_reserved, alignment);
156
157 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
158
159 os::trace_page_sizes("Heap",
160 collector_policy()->min_heap_byte_size(),
161 total_reserved,
162 alignment,
163 heap_rs->base(),
164 heap_rs->size());
165
166 return heap_rs->base();
167 }
168
169 void GenCollectedHeap::post_initialize() {
170 CollectedHeap::post_initialize();
171 ref_processing_init();
172 check_gen_kinds();
173 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
174
175 initialize_size_policy(def_new_gen->eden()->capacity(),
176 _old_gen->capacity(),
177 def_new_gen->from()->capacity());
178
179 _gen_policy->initialize_gc_policy_counters();
180 }
181
182 void GenCollectedHeap::ref_processing_init() {
183 _young_gen->ref_processor_init();
184 _old_gen->ref_processor_init();
185 }
186
187 GenerationSpec* GenCollectedHeap::young_gen_spec() const {
188 assert(_young_gen_spec != NULL, "_young_gen_spec should have been initialized");
189 return _young_gen_spec;
190 }
191
192 GenerationSpec* GenCollectedHeap::old_gen_spec() const {
193 assert(_old_gen_spec != NULL, "_old_gen_spec should have been initialized");
194 return _old_gen_spec;
195 }
196
197 size_t GenCollectedHeap::capacity() const {
198 return _young_gen->capacity() + _old_gen->capacity();
199 }
200
201 size_t GenCollectedHeap::used() const {
202 return _young_gen->used() + _old_gen->used();
203 }
204
205 void GenCollectedHeap::save_used_regions() {
206 _old_gen->save_used_region();
207 _young_gen->save_used_region();
208 }
209
210 size_t GenCollectedHeap::max_capacity() const {
211 return _young_gen->max_capacity() + _old_gen->max_capacity();
212 }
213
214 // Update the _full_collections_completed counter
215 // at the end of a stop-world full GC.
216 unsigned int GenCollectedHeap::update_full_collections_completed() {
217 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
218 assert(_full_collections_completed <= _total_full_collections,
219 "Can't complete more collections than were started");
220 _full_collections_completed = _total_full_collections;
221 ml.notify_all();
222 return _full_collections_completed;
223 }
224
225 // Update the _full_collections_completed counter, as appropriate,
226 // at the end of a concurrent GC cycle. Note the conditional update
227 // below to allow this method to be called by a concurrent collector
228 // without synchronizing in any manner with the VM thread (which
229 // may already have initiated a STW full collection "concurrently").
230 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
231 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
232 assert((_full_collections_completed <= _total_full_collections) &&
233 (count <= _total_full_collections),
234 "Can't complete more collections than were started");
235 if (count > _full_collections_completed) {
236 _full_collections_completed = count;
237 ml.notify_all();
238 }
239 return _full_collections_completed;
240 }
241
242 // Return true if any of the following is true:
243 // . the allocation won't fit into the current young gen heap
244 // . gc locker is occupied (jni critical section)
245 // . heap memory is tight -- the most recent previous collection
246 // was a full collection because a partial collection (would
247 // have) failed and is likely to fail again
248 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const {
249 size_t young_capacity = young_gen()->capacity_before_gc();
250 return (word_size > heap_word_size(young_capacity))
251 || GCLocker::is_active_and_needs_gc()
252 || incremental_collection_failed();
253 }
254
255 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) {
256 HeapWord* result = NULL;
257 if (old_gen()->should_allocate(size, is_tlab)) {
258 result = old_gen()->expand_and_allocate(size, is_tlab);
259 }
260 if (result == NULL) {
261 if (young_gen()->should_allocate(size, is_tlab)) {
262 result = young_gen()->expand_and_allocate(size, is_tlab);
263 }
264 }
265 assert(result == NULL || is_in_reserved(result), "result not in heap");
266 return result;
267 }
268
269 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size,
270 bool is_tlab,
271 bool* gc_overhead_limit_was_exceeded) {
272 debug_only(check_for_valid_allocation_state());
273 assert(no_gc_in_progress(), "Allocation during gc not allowed");
274
275 // In general gc_overhead_limit_was_exceeded should be false so
276 // set it so here and reset it to true only if the gc time
277 // limit is being exceeded as checked below.
278 *gc_overhead_limit_was_exceeded = false;
279
280 HeapWord* result = NULL;
281
282 // Loop until the allocation is satisfied, or unsatisfied after GC.
283 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) {
284 HandleMark hm; // Discard any handles allocated in each iteration.
285
286 // First allocation attempt is lock-free.
287 Generation *young = young_gen();
288 assert(young->supports_inline_contig_alloc(),
289 "Otherwise, must do alloc within heap lock");
290 if (young->should_allocate(size, is_tlab)) {
291 result = young->par_allocate(size, is_tlab);
292 if (result != NULL) {
293 assert(is_in_reserved(result), "result not in heap");
294 return result;
295 }
296 }
297 uint gc_count_before; // Read inside the Heap_lock locked region.
298 {
299 MutexLocker ml(Heap_lock);
300 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation");
301 // Note that only large objects get a shot at being
302 // allocated in later generations.
303 bool first_only = !should_try_older_generation_allocation(size);
304
305 result = attempt_allocation(size, is_tlab, first_only);
306 if (result != NULL) {
307 assert(is_in_reserved(result), "result not in heap");
308 return result;
309 }
310
311 if (GCLocker::is_active_and_needs_gc()) {
312 if (is_tlab) {
313 return NULL; // Caller will retry allocating individual object.
314 }
315 if (!is_maximal_no_gc()) {
316 // Try and expand heap to satisfy request.
317 result = expand_heap_and_allocate(size, is_tlab);
318 // Result could be null if we are out of space.
319 if (result != NULL) {
320 return result;
321 }
322 }
323
324 if (gclocker_stalled_count > GCLockerRetryAllocationCount) {
325 return NULL; // We didn't get to do a GC and we didn't get any memory.
326 }
327
328 // If this thread is not in a jni critical section, we stall
329 // the requestor until the critical section has cleared and
330 // GC allowed. When the critical section clears, a GC is
331 // initiated by the last thread exiting the critical section; so
332 // we retry the allocation sequence from the beginning of the loop,
333 // rather than causing more, now probably unnecessary, GC attempts.
334 JavaThread* jthr = JavaThread::current();
335 if (!jthr->in_critical()) {
336 MutexUnlocker mul(Heap_lock);
337 // Wait for JNI critical section to be exited
338 GCLocker::stall_until_clear();
339 gclocker_stalled_count += 1;
340 continue;
341 } else {
342 if (CheckJNICalls) {
343 fatal("Possible deadlock due to allocating while"
344 " in jni critical section");
345 }
346 return NULL;
347 }
348 }
349
350 // Read the gc count while the heap lock is held.
351 gc_count_before = total_collections();
352 }
353
354 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before);
355 VMThread::execute(&op);
356 if (op.prologue_succeeded()) {
357 result = op.result();
358 if (op.gc_locked()) {
359 assert(result == NULL, "must be NULL if gc_locked() is true");
360 continue; // Retry and/or stall as necessary.
361 }
362
363 // Allocation has failed and a collection
364 // has been done. If the gc time limit was exceeded the
365 // this time, return NULL so that an out-of-memory
366 // will be thrown. Clear gc_overhead_limit_exceeded
367 // so that the overhead exceeded does not persist.
368
369 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded();
370 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear();
371
372 if (limit_exceeded && softrefs_clear) {
373 *gc_overhead_limit_was_exceeded = true;
374 size_policy()->set_gc_overhead_limit_exceeded(false);
375 if (op.result() != NULL) {
376 CollectedHeap::fill_with_object(op.result(), size);
377 }
378 return NULL;
379 }
380 assert(result == NULL || is_in_reserved(result),
381 "result not in heap");
382 return result;
383 }
384
385 // Give a warning if we seem to be looping forever.
386 if ((QueuedAllocationWarningCount > 0) &&
387 (try_count % QueuedAllocationWarningCount == 0)) {
388 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times,"
389 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : "");
390 }
391 }
392 }
393
394 #ifndef PRODUCT
395 // Override of memory state checking method in CollectedHeap:
396 // Some collectors (CMS for example) can't have badHeapWordVal written
397 // in the first two words of an object. (For instance , in the case of
398 // CMS these words hold state used to synchronize between certain
399 // (concurrent) GC steps and direct allocating mutators.)
400 // The skip_header_HeapWords() method below, allows us to skip
401 // over the requisite number of HeapWord's. Note that (for
402 // generational collectors) this means that those many words are
403 // skipped in each object, irrespective of the generation in which
404 // that object lives. The resultant loss of precision seems to be
405 // harmless and the pain of avoiding that imprecision appears somewhat
406 // higher than we are prepared to pay for such rudimentary debugging
407 // support.
408 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
409 size_t size) {
410 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
411 // We are asked to check a size in HeapWords,
412 // but the memory is mangled in juint words.
413 juint* start = (juint*) (addr + skip_header_HeapWords());
414 juint* end = (juint*) (addr + size);
415 for (juint* slot = start; slot < end; slot += 1) {
416 assert(*slot == badHeapWordVal,
417 "Found non badHeapWordValue in pre-allocation check");
418 }
419 }
420 }
421 #endif
422
423 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
424 bool is_tlab,
425 bool first_only) {
426 HeapWord* res = NULL;
427
428 if (_young_gen->should_allocate(size, is_tlab)) {
429 res = _young_gen->allocate(size, is_tlab);
430 if (res != NULL || first_only) {
431 return res;
432 }
433 }
434
435 if (_old_gen->should_allocate(size, is_tlab)) {
436 res = _old_gen->allocate(size, is_tlab);
437 }
438
439 return res;
440 }
441
442 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
443 bool* gc_overhead_limit_was_exceeded) {
444 return mem_allocate_work(size,
445 false /* is_tlab */,
446 gc_overhead_limit_was_exceeded);
447 }
448
449 bool GenCollectedHeap::must_clear_all_soft_refs() {
450 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
451 _gc_cause == GCCause::_wb_full_gc;
452 }
453
454 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
455 bool is_tlab, bool run_verification, bool clear_soft_refs,
456 bool restore_marks_for_biased_locking) {
457 FormatBuffer<> title("Collect gen: %s", gen->short_name());
458 GCTraceTime(Trace, gc, phases) t1(title);
459 TraceCollectorStats tcs(gen->counters());
460 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
461
462 gen->stat_record()->invocations++;
463 gen->stat_record()->accumulated_time.start();
464
465 // Must be done anew before each collection because
466 // a previous collection will do mangling and will
467 // change top of some spaces.
468 record_gen_tops_before_GC();
469
470 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
471
472 if (run_verification && VerifyBeforeGC) {
473 HandleMark hm; // Discard invalid handles created during verification
474 Universe::verify("Before GC");
475 }
476 COMPILER2_PRESENT(DerivedPointerTable::clear());
477
478 if (restore_marks_for_biased_locking) {
479 // We perform this mark word preservation work lazily
480 // because it's only at this point that we know whether we
481 // absolutely have to do it; we want to avoid doing it for
482 // scavenge-only collections where it's unnecessary
483 BiasedLocking::preserve_marks();
484 }
485
486 // Do collection work
487 {
488 // Note on ref discovery: For what appear to be historical reasons,
489 // GCH enables and disabled (by enqueing) refs discovery.
490 // In the future this should be moved into the generation's
491 // collect method so that ref discovery and enqueueing concerns
492 // are local to a generation. The collect method could return
493 // an appropriate indication in the case that notification on
494 // the ref lock was needed. This will make the treatment of
495 // weak refs more uniform (and indeed remove such concerns
496 // from GCH). XXX
497
498 HandleMark hm; // Discard invalid handles created during gc
499 save_marks(); // save marks for all gens
500 // We want to discover references, but not process them yet.
501 // This mode is disabled in process_discovered_references if the
502 // generation does some collection work, or in
503 // enqueue_discovered_references if the generation returns
504 // without doing any work.
505 ReferenceProcessor* rp = gen->ref_processor();
506 // If the discovery of ("weak") refs in this generation is
507 // atomic wrt other collectors in this configuration, we
508 // are guaranteed to have empty discovered ref lists.
509 if (rp->discovery_is_atomic()) {
510 rp->enable_discovery();
511 rp->setup_policy(clear_soft_refs);
512 } else {
513 // collect() below will enable discovery as appropriate
514 }
515 gen->collect(full, clear_soft_refs, size, is_tlab);
516 if (!rp->enqueuing_is_done()) {
517 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q());
518 rp->enqueue_discovered_references(NULL, &pt);
519 pt.print_enqueue_phase();
520 } else {
521 rp->set_enqueuing_is_done(false);
522 }
523 rp->verify_no_references_recorded();
524 }
525
526 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
527
528 gen->stat_record()->accumulated_time.stop();
529
530 update_gc_stats(gen, full);
531
532 if (run_verification && VerifyAfterGC) {
533 HandleMark hm; // Discard invalid handles created during verification
534 Universe::verify("After GC");
535 }
536 }
537
538 void GenCollectedHeap::do_collection(bool full,
539 bool clear_all_soft_refs,
540 size_t size,
541 bool is_tlab,
542 GenerationType max_generation) {
543 ResourceMark rm;
544 DEBUG_ONLY(Thread* my_thread = Thread::current();)
545
546 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
547 assert(my_thread->is_VM_thread() ||
548 my_thread->is_ConcurrentGC_thread(),
549 "incorrect thread type capability");
550 assert(Heap_lock->is_locked(),
551 "the requesting thread should have the Heap_lock");
552 guarantee(!is_gc_active(), "collection is not reentrant");
553
554 if (GCLocker::check_active_before_gc()) {
555 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
556 }
557
558 GCIdMark gc_id_mark;
559
560 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
561 soft_ref_policy()->should_clear_all_soft_refs();
562
563 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy());
564
565 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
566
567 print_heap_before_gc();
568
569 {
570 FlagSetting fl(_is_gc_active, true);
571
572 bool complete = full && (max_generation == OldGen);
573 bool old_collects_young = complete && !ScavengeBeforeFullGC;
574 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
575
576 FormatBuffer<> gc_string("%s", "Pause ");
577 if (do_young_collection) {
578 gc_string.append("Young");
579 } else {
580 gc_string.append("Full");
581 }
582
583 GCTraceCPUTime tcpu;
584 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
585
586 gc_prologue(complete);
587 increment_total_collections(complete);
588
589 size_t young_prev_used = _young_gen->used();
590 size_t old_prev_used = _old_gen->used();
591
592 bool run_verification = total_collections() >= VerifyGCStartAt;
593
594 bool prepared_for_verification = false;
595 bool collected_old = false;
596
597 if (do_young_collection) {
598 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
599 prepare_for_verify();
600 prepared_for_verification = true;
601 }
602
603 collect_generation(_young_gen,
604 full,
605 size,
606 is_tlab,
607 run_verification && VerifyGCLevel <= 0,
608 do_clear_all_soft_refs,
609 false);
610
611 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
612 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
613 // Allocation request was met by young GC.
614 size = 0;
615 }
616 }
617
618 bool must_restore_marks_for_biased_locking = false;
619
620 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
621 if (!complete) {
622 // The full_collections increment was missed above.
623 increment_total_full_collections();
624 }
625
626 if (!prepared_for_verification && run_verification &&
627 VerifyGCLevel <= 1 && VerifyBeforeGC) {
628 prepare_for_verify();
629 }
630
631 if (do_young_collection) {
632 // We did a young GC. Need a new GC id for the old GC.
633 GCIdMark gc_id_mark;
634 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
635 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
636 } else {
637 // No young GC done. Use the same GC id as was set up earlier in this method.
638 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
639 }
640
641 must_restore_marks_for_biased_locking = true;
642 collected_old = true;
643 }
644
645 // Update "complete" boolean wrt what actually transpired --
646 // for instance, a promotion failure could have led to
647 // a whole heap collection.
648 complete = complete || collected_old;
649
650 print_heap_change(young_prev_used, old_prev_used);
651 MetaspaceAux::print_metaspace_change(metadata_prev_used);
652
653 // Adjust generation sizes.
654 if (collected_old) {
655 _old_gen->compute_new_size();
656 }
657 _young_gen->compute_new_size();
658
659 if (complete) {
660 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
661 ClassLoaderDataGraph::purge();
662 MetaspaceAux::verify_metrics();
663 // Resize the metaspace capacity after full collections
664 MetaspaceGC::compute_new_size();
665 update_full_collections_completed();
666 }
667
668 // Track memory usage and detect low memory after GC finishes
669 MemoryService::track_memory_usage();
670
671 gc_epilogue(complete);
672
673 if (must_restore_marks_for_biased_locking) {
674 BiasedLocking::restore_marks();
675 }
676 }
677
678 print_heap_after_gc();
679
680 #ifdef TRACESPINNING
681 ParallelTaskTerminator::print_termination_counts();
682 #endif
683 }
684
685 void GenCollectedHeap::register_nmethod(nmethod* nm) {
686 CodeCache::register_scavenge_root_nmethod(nm);
687 }
688
689 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
690 CodeCache::verify_scavenge_root_nmethod(nm);
691 }
692
693 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
694 GCCauseSetter x(this, GCCause::_allocation_failure);
695 HeapWord* result = NULL;
696
697 assert(size != 0, "Precondition violated");
698 if (GCLocker::is_active_and_needs_gc()) {
699 // GC locker is active; instead of a collection we will attempt
700 // to expand the heap, if there's room for expansion.
701 if (!is_maximal_no_gc()) {
702 result = expand_heap_and_allocate(size, is_tlab);
703 }
704 return result; // Could be null if we are out of space.
705 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) {
706 // Do an incremental collection.
707 do_collection(false, // full
708 false, // clear_all_soft_refs
709 size, // size
710 is_tlab, // is_tlab
711 GenCollectedHeap::OldGen); // max_generation
712 } else {
713 log_trace(gc)(" :: Trying full because partial may fail :: ");
714 // Try a full collection; see delta for bug id 6266275
715 // for the original code and why this has been simplified
716 // with from-space allocation criteria modified and
717 // such allocation moved out of the safepoint path.
718 do_collection(true, // full
719 false, // clear_all_soft_refs
720 size, // size
721 is_tlab, // is_tlab
722 GenCollectedHeap::OldGen); // max_generation
723 }
724
725 result = attempt_allocation(size, is_tlab, false /*first_only*/);
726
727 if (result != NULL) {
728 assert(is_in_reserved(result), "result not in heap");
729 return result;
730 }
731
732 // OK, collection failed, try expansion.
733 result = expand_heap_and_allocate(size, is_tlab);
734 if (result != NULL) {
735 return result;
736 }
737
738 // If we reach this point, we're really out of memory. Try every trick
739 // we can to reclaim memory. Force collection of soft references. Force
740 // a complete compaction of the heap. Any additional methods for finding
741 // free memory should be here, especially if they are expensive. If this
742 // attempt fails, an OOM exception will be thrown.
743 {
744 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted
745
746 do_collection(true, // full
747 true, // clear_all_soft_refs
748 size, // size
749 is_tlab, // is_tlab
750 GenCollectedHeap::OldGen); // max_generation
751 }
752
753 result = attempt_allocation(size, is_tlab, false /* first_only */);
754 if (result != NULL) {
755 assert(is_in_reserved(result), "result not in heap");
756 return result;
757 }
758
759 assert(!soft_ref_policy()->should_clear_all_soft_refs(),
760 "Flag should have been handled and cleared prior to this point");
761
762 // What else? We might try synchronous finalization later. If the total
763 // space available is large enough for the allocation, then a more
764 // complete compaction phase than we've tried so far might be
765 // appropriate.
766 return NULL;
767 }
768
769 #ifdef ASSERT
770 class AssertNonScavengableClosure: public OopClosure {
771 public:
772 virtual void do_oop(oop* p) {
773 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
774 "Referent should not be scavengable."); }
775 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
776 };
777 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
778 #endif
779
780 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
781 ScanningOption so,
782 OopClosure* strong_roots,
783 OopClosure* weak_roots,
784 CLDClosure* strong_cld_closure,
785 CLDClosure* weak_cld_closure,
786 CodeBlobToOopClosure* code_roots) {
787 // General roots.
788 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
789 assert(code_roots != NULL, "code root closure should always be set");
790 // _n_termination for _process_strong_tasks should be set up stream
791 // in a method not running in a GC worker. Otherwise the GC worker
792 // could be trying to change the termination condition while the task
793 // is executing in another GC worker.
794
795 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
796 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
797 }
798
799 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
800 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
801
802 bool is_par = scope->n_threads() > 1;
803 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
804
805 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
806 Universe::oops_do(strong_roots);
807 }
808 // Global (strong) JNI handles
809 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
810 JNIHandles::oops_do(strong_roots);
811 }
812
813 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
814 ObjectSynchronizer::oops_do(strong_roots);
815 }
816 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
817 Management::oops_do(strong_roots);
818 }
819 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
820 JvmtiExport::oops_do(strong_roots);
821 }
822 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
823 AOTLoader::oops_do(strong_roots);
824 }
825
826 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
827 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
828 }
829
830 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
831 if (so & SO_ScavengeCodeCache) {
832 assert(code_roots != NULL, "must supply closure for code cache");
833
834 // We only visit parts of the CodeCache when scavenging.
835 CodeCache::scavenge_root_nmethods_do(code_roots);
836 }
837 if (so & SO_AllCodeCache) {
838 assert(code_roots != NULL, "must supply closure for code cache");
839
840 // CMSCollector uses this to do intermediate-strength collections.
841 // We scan the entire code cache, since CodeCache::do_unloading is not called.
842 CodeCache::blobs_do(code_roots);
843 }
844 // Verify that the code cache contents are not subject to
845 // movement by a scavenging collection.
846 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
847 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
848 }
849 }
850
851 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
852 OopClosure* root_closure) {
853 assert(root_closure != NULL, "Must be set");
854 // All threads execute the following. A specific chunk of buckets
855 // from the StringTable are the individual tasks.
856 if (scope->n_threads() > 1) {
857 StringTable::possibly_parallel_oops_do(root_closure);
858 } else {
859 StringTable::oops_do(root_closure);
860 }
861 }
862
863 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
864 OopsInGenClosure* root_closure,
865 OopsInGenClosure* old_gen_closure,
866 CLDClosure* cld_closure) {
867 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
868
869 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
870 cld_closure, cld_closure, &mark_code_closure);
871 process_string_table_roots(scope, root_closure);
872
873 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
874 root_closure->reset_generation();
875 }
876
877 // When collection is parallel, all threads get to cooperate to do
878 // old generation scanning.
879 old_gen_closure->set_generation(_old_gen);
880 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
881 old_gen_closure->reset_generation();
882
883 _process_strong_tasks->all_tasks_completed(scope->n_threads());
884 }
885
886 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
887 bool is_adjust_phase,
888 ScanningOption so,
889 bool only_strong_roots,
890 OopsInGenClosure* root_closure,
891 CLDClosure* cld_closure) {
892 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
893 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
894 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
895
896 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
897 if (is_adjust_phase) {
898 // We never treat the string table as roots during marking
899 // for the full gc, so we only need to process it during
900 // the adjust phase.
901 process_string_table_roots(scope, root_closure);
902 }
903
904 _process_strong_tasks->all_tasks_completed(scope->n_threads());
905 }
906
907 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
908 WeakProcessor::oops_do(root_closure);
909 _young_gen->ref_processor()->weak_oops_do(root_closure);
910 _old_gen->ref_processor()->weak_oops_do(root_closure);
911 }
912
913 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
914 void GenCollectedHeap:: \
915 oop_since_save_marks_iterate(GenerationType gen, \
916 OopClosureType* cur, \
917 OopClosureType* older) { \
918 if (gen == YoungGen) { \
919 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
920 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
921 } else { \
922 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
923 } \
924 }
925
926 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
927
928 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
929
930 bool GenCollectedHeap::no_allocs_since_save_marks() {
931 return _young_gen->no_allocs_since_save_marks() &&
932 _old_gen->no_allocs_since_save_marks();
933 }
934
935 bool GenCollectedHeap::supports_inline_contig_alloc() const {
936 return _young_gen->supports_inline_contig_alloc();
937 }
938
939 HeapWord* volatile* GenCollectedHeap::top_addr() const {
940 return _young_gen->top_addr();
941 }
942
943 HeapWord** GenCollectedHeap::end_addr() const {
944 return _young_gen->end_addr();
945 }
946
947 // public collection interfaces
948
949 void GenCollectedHeap::collect(GCCause::Cause cause) {
950 if (cause == GCCause::_wb_young_gc) {
951 // Young collection for the WhiteBox API.
952 collect(cause, YoungGen);
953 } else {
954 #ifdef ASSERT
955 if (cause == GCCause::_scavenge_alot) {
956 // Young collection only.
957 collect(cause, YoungGen);
958 } else {
959 // Stop-the-world full collection.
960 collect(cause, OldGen);
961 }
962 #else
963 // Stop-the-world full collection.
964 collect(cause, OldGen);
965 #endif
966 }
967 }
968
969 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
970 // The caller doesn't have the Heap_lock
971 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
972 MutexLocker ml(Heap_lock);
973 collect_locked(cause, max_generation);
974 }
975
976 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
977 // The caller has the Heap_lock
978 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
979 collect_locked(cause, OldGen);
980 }
981
982 // this is the private collection interface
983 // The Heap_lock is expected to be held on entry.
984
985 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
986 // Read the GC count while holding the Heap_lock
987 unsigned int gc_count_before = total_collections();
988 unsigned int full_gc_count_before = total_full_collections();
989 {
990 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
991 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
992 cause, max_generation);
993 VMThread::execute(&op);
994 }
995 }
996
997 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
998 do_full_collection(clear_all_soft_refs, OldGen);
999 }
1000
1001 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
1002 GenerationType last_generation) {
1003 GenerationType local_last_generation;
1004 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
1005 gc_cause() == GCCause::_gc_locker) {
1006 local_last_generation = YoungGen;
1007 } else {
1008 local_last_generation = last_generation;
1009 }
1010
1011 do_collection(true, // full
1012 clear_all_soft_refs, // clear_all_soft_refs
1013 0, // size
1014 false, // is_tlab
1015 local_last_generation); // last_generation
1016 // Hack XXX FIX ME !!!
1017 // A scavenge may not have been attempted, or may have
1018 // been attempted and failed, because the old gen was too full
1019 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
1020 incremental_collection_will_fail(false /* don't consult_young */)) {
1021 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
1022 // This time allow the old gen to be collected as well
1023 do_collection(true, // full
1024 clear_all_soft_refs, // clear_all_soft_refs
1025 0, // size
1026 false, // is_tlab
1027 OldGen); // last_generation
1028 }
1029 }
1030
1031 bool GenCollectedHeap::is_in_young(oop p) {
1032 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
1033 assert(result == _young_gen->is_in_reserved(p),
1034 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
1035 return result;
1036 }
1037
1038 // Returns "TRUE" iff "p" points into the committed areas of the heap.
1039 bool GenCollectedHeap::is_in(const void* p) const {
1040 return _young_gen->is_in(p) || _old_gen->is_in(p);
1041 }
1042
1043 #ifdef ASSERT
1044 // Don't implement this by using is_in_young(). This method is used
1045 // in some cases to check that is_in_young() is correct.
1046 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
1047 assert(is_in_reserved(p) || p == NULL,
1048 "Does not work if address is non-null and outside of the heap");
1049 return p < _young_gen->reserved().end() && p != NULL;
1050 }
1051 #endif
1052
1053 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
1054 NoHeaderExtendedOopClosure no_header_cl(cl);
1055 oop_iterate(&no_header_cl);
1056 }
1057
1058 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
1059 _young_gen->oop_iterate(cl);
1060 _old_gen->oop_iterate(cl);
1061 }
1062
1063 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
1064 _young_gen->object_iterate(cl);
1065 _old_gen->object_iterate(cl);
1066 }
1067
1068 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
1069 _young_gen->safe_object_iterate(cl);
1070 _old_gen->safe_object_iterate(cl);
1071 }
1072
1073 Space* GenCollectedHeap::space_containing(const void* addr) const {
1074 Space* res = _young_gen->space_containing(addr);
1075 if (res != NULL) {
1076 return res;
1077 }
1078 res = _old_gen->space_containing(addr);
1079 assert(res != NULL, "Could not find containing space");
1080 return res;
1081 }
1082
1083 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
1084 assert(is_in_reserved(addr), "block_start of address outside of heap");
1085 if (_young_gen->is_in_reserved(addr)) {
1086 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1087 return _young_gen->block_start(addr);
1088 }
1089
1090 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1091 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1092 return _old_gen->block_start(addr);
1093 }
1094
1095 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
1096 assert(is_in_reserved(addr), "block_size of address outside of heap");
1097 if (_young_gen->is_in_reserved(addr)) {
1098 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
1099 return _young_gen->block_size(addr);
1100 }
1101
1102 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1103 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
1104 return _old_gen->block_size(addr);
1105 }
1106
1107 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
1108 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
1109 assert(block_start(addr) == addr, "addr must be a block start");
1110 if (_young_gen->is_in_reserved(addr)) {
1111 return _young_gen->block_is_obj(addr);
1112 }
1113
1114 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
1115 return _old_gen->block_is_obj(addr);
1116 }
1117
1118 bool GenCollectedHeap::supports_tlab_allocation() const {
1119 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1120 return _young_gen->supports_tlab_allocation();
1121 }
1122
1123 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1124 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1125 if (_young_gen->supports_tlab_allocation()) {
1126 return _young_gen->tlab_capacity();
1127 }
1128 return 0;
1129 }
1130
1131 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1132 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1133 if (_young_gen->supports_tlab_allocation()) {
1134 return _young_gen->tlab_used();
1135 }
1136 return 0;
1137 }
1138
1139 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1140 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1141 if (_young_gen->supports_tlab_allocation()) {
1142 return _young_gen->unsafe_max_tlab_alloc();
1143 }
1144 return 0;
1145 }
1146
1147 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1148 bool gc_overhead_limit_was_exceeded;
1149 return mem_allocate_work(size /* size */,
1150 true /* is_tlab */,
1151 &gc_overhead_limit_was_exceeded);
1152 }
1153
1154 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
1155 // from the list headed by "*prev_ptr".
1156 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1157 bool first = true;
1158 size_t min_size = 0; // "first" makes this conceptually infinite.
1159 ScratchBlock **smallest_ptr, *smallest;
1160 ScratchBlock *cur = *prev_ptr;
1161 while (cur) {
1162 assert(*prev_ptr == cur, "just checking");
1163 if (first || cur->num_words < min_size) {
1164 smallest_ptr = prev_ptr;
1165 smallest = cur;
1166 min_size = smallest->num_words;
1167 first = false;
1168 }
1169 prev_ptr = &cur->next;
1170 cur = cur->next;
1171 }
1172 smallest = *smallest_ptr;
1173 *smallest_ptr = smallest->next;
1174 return smallest;
1175 }
1176
1177 // Sort the scratch block list headed by res into decreasing size order,
1178 // and set "res" to the result.
1179 static void sort_scratch_list(ScratchBlock*& list) {
1180 ScratchBlock* sorted = NULL;
1181 ScratchBlock* unsorted = list;
1182 while (unsorted) {
1183 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1184 smallest->next = sorted;
1185 sorted = smallest;
1186 }
1187 list = sorted;
1188 }
1189
1190 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1191 size_t max_alloc_words) {
1192 ScratchBlock* res = NULL;
1193 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1194 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1195 sort_scratch_list(res);
1196 return res;
1197 }
1198
1199 void GenCollectedHeap::release_scratch() {
1200 _young_gen->reset_scratch();
1201 _old_gen->reset_scratch();
1202 }
1203
1204 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1205 void do_generation(Generation* gen) {
1206 gen->prepare_for_verify();
1207 }
1208 };
1209
1210 void GenCollectedHeap::prepare_for_verify() {
1211 ensure_parsability(false); // no need to retire TLABs
1212 GenPrepareForVerifyClosure blk;
1213 generation_iterate(&blk, false);
1214 }
1215
1216 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1217 bool old_to_young) {
1218 if (old_to_young) {
1219 cl->do_generation(_old_gen);
1220 cl->do_generation(_young_gen);
1221 } else {
1222 cl->do_generation(_young_gen);
1223 cl->do_generation(_old_gen);
1224 }
1225 }
1226
1227 bool GenCollectedHeap::is_maximal_no_gc() const {
1228 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1229 }
1230
1231 void GenCollectedHeap::save_marks() {
1232 _young_gen->save_marks();
1233 _old_gen->save_marks();
1234 }
1235
1236 GenCollectedHeap* GenCollectedHeap::heap() {
1237 CollectedHeap* heap = Universe::heap();
1238 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1239 assert(heap->kind() == CollectedHeap::SerialHeap ||
1240 heap->kind() == CollectedHeap::CMSHeap, "Not a GenCollectedHeap");
1241 return (GenCollectedHeap*) heap;
1242 }
1243
1244 void GenCollectedHeap::prepare_for_compaction() {
1245 // Start by compacting into same gen.
1246 CompactPoint cp(_old_gen);
1247 _old_gen->prepare_for_compaction(&cp);
1248 _young_gen->prepare_for_compaction(&cp);
1249 }
1250
1251 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
1252 log_debug(gc, verify)("%s", _old_gen->name());
1253 _old_gen->verify();
1254
1255 log_debug(gc, verify)("%s", _old_gen->name());
1256 _young_gen->verify();
1257
1258 log_debug(gc, verify)("RemSet");
1259 rem_set()->verify();
1260 }
1261
1262 void GenCollectedHeap::print_on(outputStream* st) const {
1263 _young_gen->print_on(st);
1264 _old_gen->print_on(st);
1265 MetaspaceAux::print_on(st);
1266 }
1267
1268 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1269 }
1270
1271 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1272 }
1273
1274 void GenCollectedHeap::print_tracing_info() const {
1275 if (log_is_enabled(Debug, gc, heap, exit)) {
1276 LogStreamHandle(Debug, gc, heap, exit) lsh;
1277 _young_gen->print_summary_info_on(&lsh);
1278 _old_gen->print_summary_info_on(&lsh);
1279 }
1280 }
1281
1282 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1283 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1284 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1285 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1286 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1287 }
1288
1289 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1290 private:
1291 bool _full;
1292 public:
1293 void do_generation(Generation* gen) {
1294 gen->gc_prologue(_full);
1295 }
1296 GenGCPrologueClosure(bool full) : _full(full) {};
1297 };
1298
1299 void GenCollectedHeap::gc_prologue(bool full) {
1300 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1301
1302 // Fill TLAB's and such
1303 CollectedHeap::accumulate_statistics_all_tlabs();
1304 ensure_parsability(true); // retire TLABs
1305
1306 // Walk generations
1307 GenGCPrologueClosure blk(full);
1308 generation_iterate(&blk, false); // not old-to-young.
1309 };
1310
1311 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1312 private:
1313 bool _full;
1314 public:
1315 void do_generation(Generation* gen) {
1316 gen->gc_epilogue(_full);
1317 }
1318 GenGCEpilogueClosure(bool full) : _full(full) {};
1319 };
1320
1321 void GenCollectedHeap::gc_epilogue(bool full) {
1322 #if COMPILER2_OR_JVMCI
1323 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1324 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1325 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1326 #endif // COMPILER2_OR_JVMCI
1327
1328 resize_all_tlabs();
1329
1330 GenGCEpilogueClosure blk(full);
1331 generation_iterate(&blk, false); // not old-to-young.
1332
1333 if (!CleanChunkPoolAsync) {
1334 Chunk::clean_chunk_pool();
1335 }
1336
1337 MetaspaceCounters::update_performance_counters();
1338 CompressedClassSpaceCounters::update_performance_counters();
1339 };
1340
1341 #ifndef PRODUCT
1342 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1343 private:
1344 public:
1345 void do_generation(Generation* gen) {
1346 gen->record_spaces_top();
1347 }
1348 };
1349
1350 void GenCollectedHeap::record_gen_tops_before_GC() {
1351 if (ZapUnusedHeapArea) {
1352 GenGCSaveTopsBeforeGCClosure blk;
1353 generation_iterate(&blk, false); // not old-to-young.
1354 }
1355 }
1356 #endif // not PRODUCT
1357
1358 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1359 public:
1360 void do_generation(Generation* gen) {
1361 gen->ensure_parsability();
1362 }
1363 };
1364
1365 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1366 CollectedHeap::ensure_parsability(retire_tlabs);
1367 GenEnsureParsabilityClosure ep_cl;
1368 generation_iterate(&ep_cl, false);
1369 }
1370
1371 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1372 oop obj,
1373 size_t obj_size) {
1374 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1375 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1376 HeapWord* result = NULL;
1377
1378 result = old_gen->expand_and_allocate(obj_size, false);
1379
1380 if (result != NULL) {
1381 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1382 }
1383 return oop(result);
1384 }
1385
1386 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1387 jlong _time; // in ms
1388 jlong _now; // in ms
1389
1390 public:
1391 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1392
1393 jlong time() { return _time; }
1394
1395 void do_generation(Generation* gen) {
1396 _time = MIN2(_time, gen->time_of_last_gc(_now));
1397 }
1398 };
1399
1400 jlong GenCollectedHeap::millis_since_last_gc() {
1401 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1402 // provided the underlying platform provides such a time source
1403 // (and it is bug free). So we still have to guard against getting
1404 // back a time later than 'now'.
1405 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1406 GenTimeOfLastGCClosure tolgc_cl(now);
1407 // iterate over generations getting the oldest
1408 // time that a generation was collected
1409 generation_iterate(&tolgc_cl, false);
1410
1411 jlong retVal = now - tolgc_cl.time();
1412 if (retVal < 0) {
1413 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1414 ". returning zero instead.", retVal);
1415 return 0;
1416 }
1417 return retVal;
1418 }