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