1 /*
2 * Copyright (c) 2000, 2017, 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/collectedHeap.inline.hpp"
34 #include "gc/shared/collectorCounters.hpp"
35 #include "gc/shared/gcId.hpp"
36 #include "gc/shared/gcLocker.inline.hpp"
37 #include "gc/shared/gcTrace.hpp"
38 #include "gc/shared/gcTraceTime.inline.hpp"
39 #include "gc/shared/genCollectedHeap.hpp"
40 #include "gc/shared/genOopClosures.inline.hpp"
41 #include "gc/shared/generationSpec.hpp"
42 #include "gc/shared/space.hpp"
43 #include "gc/shared/strongRootsScope.hpp"
44 #include "gc/shared/vmGCOperations.hpp"
45 #include "gc/shared/weakProcessor.hpp"
46 #include "gc/shared/workgroup.hpp"
47 #include "memory/filemap.hpp"
48 #include "memory/resourceArea.hpp"
49 #include "oops/oop.inline.hpp"
50 #include "runtime/biasedLocking.hpp"
51 #include "runtime/handles.hpp"
52 #include "runtime/handles.inline.hpp"
53 #include "runtime/java.hpp"
54 #include "runtime/vmThread.hpp"
55 #include "services/management.hpp"
56 #include "services/memoryService.hpp"
57 #include "utilities/debug.hpp"
58 #include "utilities/formatBuffer.hpp"
59 #include "utilities/macros.hpp"
60 #include "utilities/stack.inline.hpp"
61 #include "utilities/vmError.hpp"
62
63 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
64 CollectedHeap(),
65 _rem_set(NULL),
66 _gen_policy(policy),
67 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
68 _full_collections_completed(0)
69 {
70 assert(policy != NULL, "Sanity check");
71 }
72
73 jint GenCollectedHeap::initialize() {
74 CollectedHeap::pre_initialize();
75
76 // While there are no constraints in the GC code that HeapWordSize
77 // be any particular value, there are multiple other areas in the
78 // system which believe this to be true (e.g. oop->object_size in some
79 // cases incorrectly returns the size in wordSize units rather than
80 // HeapWordSize).
81 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
82
83 // Allocate space for the heap.
84
85 char* heap_address;
86 ReservedSpace heap_rs;
87
88 size_t heap_alignment = collector_policy()->heap_alignment();
89
90 heap_address = allocate(heap_alignment, &heap_rs);
91
92 if (!heap_rs.is_reserved()) {
93 vm_shutdown_during_initialization(
94 "Could not reserve enough space for object heap");
95 return JNI_ENOMEM;
96 }
97
98 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
99
100 _rem_set = collector_policy()->create_rem_set(reserved_region());
101 set_barrier_set(rem_set()->bs());
102
103 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
104 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set());
105 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
106
107 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
108 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set());
109 clear_incremental_collection_failed();
110
111 return JNI_OK;
112 }
113
114 char* GenCollectedHeap::allocate(size_t alignment,
115 ReservedSpace* heap_rs){
116 // Now figure out the total size.
117 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
118 assert(alignment % pageSize == 0, "Must be");
119
120 GenerationSpec* young_spec = gen_policy()->young_gen_spec();
121 GenerationSpec* old_spec = gen_policy()->old_gen_spec();
122
123 // Check for overflow.
124 size_t total_reserved = young_spec->max_size() + old_spec->max_size();
125 if (total_reserved < young_spec->max_size()) {
126 vm_exit_during_initialization("The size of the object heap + VM data exceeds "
127 "the maximum representable size");
128 }
129 assert(total_reserved % alignment == 0,
130 "Gen size; total_reserved=" SIZE_FORMAT ", alignment="
131 SIZE_FORMAT, total_reserved, alignment);
132
133 *heap_rs = Universe::reserve_heap(total_reserved, alignment);
134
135 os::trace_page_sizes("Heap",
136 collector_policy()->min_heap_byte_size(),
137 total_reserved,
138 alignment,
139 heap_rs->base(),
140 heap_rs->size());
141
142 return heap_rs->base();
143 }
144
145 void GenCollectedHeap::post_initialize() {
146 CollectedHeap::post_initialize();
147 ref_processing_init();
148 check_gen_kinds();
149 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
150
151 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(),
152 _old_gen->capacity(),
153 def_new_gen->from()->capacity());
154 _gen_policy->initialize_gc_policy_counters();
155 }
156
157 void GenCollectedHeap::ref_processing_init() {
158 _young_gen->ref_processor_init();
159 _old_gen->ref_processor_init();
160 }
161
162 size_t GenCollectedHeap::capacity() const {
163 return _young_gen->capacity() + _old_gen->capacity();
164 }
165
166 size_t GenCollectedHeap::used() const {
167 return _young_gen->used() + _old_gen->used();
168 }
169
170 void GenCollectedHeap::save_used_regions() {
171 _old_gen->save_used_region();
172 _young_gen->save_used_region();
173 }
174
175 size_t GenCollectedHeap::max_capacity() const {
176 return _young_gen->max_capacity() + _old_gen->max_capacity();
177 }
178
179 // Update the _full_collections_completed counter
180 // at the end of a stop-world full GC.
181 unsigned int GenCollectedHeap::update_full_collections_completed() {
182 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
183 assert(_full_collections_completed <= _total_full_collections,
184 "Can't complete more collections than were started");
185 _full_collections_completed = _total_full_collections;
186 ml.notify_all();
187 return _full_collections_completed;
188 }
189
190 // Update the _full_collections_completed counter, as appropriate,
191 // at the end of a concurrent GC cycle. Note the conditional update
192 // below to allow this method to be called by a concurrent collector
193 // without synchronizing in any manner with the VM thread (which
194 // may already have initiated a STW full collection "concurrently").
195 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
196 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
197 assert((_full_collections_completed <= _total_full_collections) &&
198 (count <= _total_full_collections),
199 "Can't complete more collections than were started");
200 if (count > _full_collections_completed) {
201 _full_collections_completed = count;
202 ml.notify_all();
203 }
204 return _full_collections_completed;
205 }
206
207
208 #ifndef PRODUCT
209 // Override of memory state checking method in CollectedHeap:
210 // Some collectors (CMS for example) can't have badHeapWordVal written
211 // in the first two words of an object. (For instance , in the case of
212 // CMS these words hold state used to synchronize between certain
213 // (concurrent) GC steps and direct allocating mutators.)
214 // The skip_header_HeapWords() method below, allows us to skip
215 // over the requisite number of HeapWord's. Note that (for
216 // generational collectors) this means that those many words are
217 // skipped in each object, irrespective of the generation in which
218 // that object lives. The resultant loss of precision seems to be
219 // harmless and the pain of avoiding that imprecision appears somewhat
220 // higher than we are prepared to pay for such rudimentary debugging
221 // support.
222 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
223 size_t size) {
224 if (CheckMemoryInitialization && ZapUnusedHeapArea) {
225 // We are asked to check a size in HeapWords,
226 // but the memory is mangled in juint words.
227 juint* start = (juint*) (addr + skip_header_HeapWords());
228 juint* end = (juint*) (addr + size);
229 for (juint* slot = start; slot < end; slot += 1) {
230 assert(*slot == badHeapWordVal,
231 "Found non badHeapWordValue in pre-allocation check");
232 }
233 }
234 }
235 #endif
236
237 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
238 bool is_tlab,
239 bool first_only) {
240 HeapWord* res = NULL;
241
242 if (_young_gen->should_allocate(size, is_tlab)) {
243 res = _young_gen->allocate(size, is_tlab);
244 if (res != NULL || first_only) {
245 return res;
246 }
247 }
248
249 if (_old_gen->should_allocate(size, is_tlab)) {
250 res = _old_gen->allocate(size, is_tlab);
251 }
252
253 return res;
254 }
255
256 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
257 bool* gc_overhead_limit_was_exceeded) {
258 return gen_policy()->mem_allocate_work(size,
259 false /* is_tlab */,
260 gc_overhead_limit_was_exceeded);
261 }
262
263 bool GenCollectedHeap::must_clear_all_soft_refs() {
264 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs ||
265 _gc_cause == GCCause::_wb_full_gc;
266 }
267
268 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
269 bool is_tlab, bool run_verification, bool clear_soft_refs,
270 bool restore_marks_for_biased_locking) {
271 FormatBuffer<> title("Collect gen: %s", gen->short_name());
272 GCTraceTime(Trace, gc, phases) t1(title);
273 TraceCollectorStats tcs(gen->counters());
274 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause());
275
276 gen->stat_record()->invocations++;
277 gen->stat_record()->accumulated_time.start();
278
279 // Must be done anew before each collection because
280 // a previous collection will do mangling and will
281 // change top of some spaces.
282 record_gen_tops_before_GC();
283
284 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize);
285
286 if (run_verification && VerifyBeforeGC) {
287 HandleMark hm; // Discard invalid handles created during verification
288 Universe::verify("Before GC");
289 }
290 COMPILER2_PRESENT(DerivedPointerTable::clear());
291
292 if (restore_marks_for_biased_locking) {
293 // We perform this mark word preservation work lazily
294 // because it's only at this point that we know whether we
295 // absolutely have to do it; we want to avoid doing it for
296 // scavenge-only collections where it's unnecessary
297 BiasedLocking::preserve_marks();
298 }
299
300 // Do collection work
301 {
302 // Note on ref discovery: For what appear to be historical reasons,
303 // GCH enables and disabled (by enqueing) refs discovery.
304 // In the future this should be moved into the generation's
305 // collect method so that ref discovery and enqueueing concerns
306 // are local to a generation. The collect method could return
307 // an appropriate indication in the case that notification on
308 // the ref lock was needed. This will make the treatment of
309 // weak refs more uniform (and indeed remove such concerns
310 // from GCH). XXX
311
312 HandleMark hm; // Discard invalid handles created during gc
313 save_marks(); // save marks for all gens
314 // We want to discover references, but not process them yet.
315 // This mode is disabled in process_discovered_references if the
316 // generation does some collection work, or in
317 // enqueue_discovered_references if the generation returns
318 // without doing any work.
319 ReferenceProcessor* rp = gen->ref_processor();
320 // If the discovery of ("weak") refs in this generation is
321 // atomic wrt other collectors in this configuration, we
322 // are guaranteed to have empty discovered ref lists.
323 if (rp->discovery_is_atomic()) {
324 rp->enable_discovery();
325 rp->setup_policy(clear_soft_refs);
326 } else {
327 // collect() below will enable discovery as appropriate
328 }
329 gen->collect(full, clear_soft_refs, size, is_tlab);
330 if (!rp->enqueuing_is_done()) {
331 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q());
332 rp->enqueue_discovered_references(NULL, &pt);
333 pt.print_enqueue_phase();
334 } else {
335 rp->set_enqueuing_is_done(false);
336 }
337 rp->verify_no_references_recorded();
338 }
339
340 COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
341
342 gen->stat_record()->accumulated_time.stop();
343
344 update_gc_stats(gen, full);
345
346 if (run_verification && VerifyAfterGC) {
347 HandleMark hm; // Discard invalid handles created during verification
348 Universe::verify("After GC");
349 }
350 }
351
352 void GenCollectedHeap::do_collection(bool full,
353 bool clear_all_soft_refs,
354 size_t size,
355 bool is_tlab,
356 GenerationType max_generation) {
357 ResourceMark rm;
358 DEBUG_ONLY(Thread* my_thread = Thread::current();)
359
360 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
361 assert(my_thread->is_VM_thread() ||
362 my_thread->is_ConcurrentGC_thread(),
363 "incorrect thread type capability");
364 assert(Heap_lock->is_locked(),
365 "the requesting thread should have the Heap_lock");
366 guarantee(!is_gc_active(), "collection is not reentrant");
367
368 if (GCLocker::check_active_before_gc()) {
369 return; // GC is disabled (e.g. JNI GetXXXCritical operation)
370 }
371
372 GCIdMarkAndRestore gc_id_mark;
373
374 const bool do_clear_all_soft_refs = clear_all_soft_refs ||
375 collector_policy()->should_clear_all_soft_refs();
376
377 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
378
379 const size_t metadata_prev_used = MetaspaceAux::used_bytes();
380
381 print_heap_before_gc();
382
383 {
384 FlagSetting fl(_is_gc_active, true);
385
386 bool complete = full && (max_generation == OldGen);
387 bool old_collects_young = complete && !ScavengeBeforeFullGC;
388 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab);
389
390 FormatBuffer<> gc_string("%s", "Pause ");
391 if (do_young_collection) {
392 gc_string.append("Young");
393 } else {
394 gc_string.append("Full");
395 }
396
397 GCTraceCPUTime tcpu;
398 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true);
399
400 gc_prologue(complete);
401 increment_total_collections(complete);
402
403 size_t young_prev_used = _young_gen->used();
404 size_t old_prev_used = _old_gen->used();
405
406 bool run_verification = total_collections() >= VerifyGCStartAt;
407
408 bool prepared_for_verification = false;
409 bool collected_old = false;
410
411 if (do_young_collection) {
412 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
413 prepare_for_verify();
414 prepared_for_verification = true;
415 }
416
417 collect_generation(_young_gen,
418 full,
419 size,
420 is_tlab,
421 run_verification && VerifyGCLevel <= 0,
422 do_clear_all_soft_refs,
423 false);
424
425 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
426 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
427 // Allocation request was met by young GC.
428 size = 0;
429 }
430 }
431
432 bool must_restore_marks_for_biased_locking = false;
433
434 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
435 if (!complete) {
436 // The full_collections increment was missed above.
437 increment_total_full_collections();
438 }
439
440 if (!prepared_for_verification && run_verification &&
441 VerifyGCLevel <= 1 && VerifyBeforeGC) {
442 prepare_for_verify();
443 }
444
445 if (do_young_collection) {
446 // We did a young GC. Need a new GC id for the old GC.
447 GCIdMarkAndRestore gc_id_mark;
448 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true);
449 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
450 } else {
451 // No young GC done. Use the same GC id as was set up earlier in this method.
452 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true);
453 }
454
455 must_restore_marks_for_biased_locking = true;
456 collected_old = true;
457 }
458
459 // Update "complete" boolean wrt what actually transpired --
460 // for instance, a promotion failure could have led to
461 // a whole heap collection.
462 complete = complete || collected_old;
463
464 print_heap_change(young_prev_used, old_prev_used);
465 MetaspaceAux::print_metaspace_change(metadata_prev_used);
466
467 // Adjust generation sizes.
468 if (collected_old) {
469 _old_gen->compute_new_size();
470 }
471 _young_gen->compute_new_size();
472
473 if (complete) {
474 // Delete metaspaces for unloaded class loaders and clean up loader_data graph
475 ClassLoaderDataGraph::purge();
476 MetaspaceAux::verify_metrics();
477 // Resize the metaspace capacity after full collections
478 MetaspaceGC::compute_new_size();
479 update_full_collections_completed();
480 }
481
482 // Track memory usage and detect low memory after GC finishes
483 MemoryService::track_memory_usage();
484
485 gc_epilogue(complete);
486
487 if (must_restore_marks_for_biased_locking) {
488 BiasedLocking::restore_marks();
489 }
490 }
491
492 print_heap_after_gc();
493
494 #ifdef TRACESPINNING
495 ParallelTaskTerminator::print_termination_counts();
496 #endif
497 }
498
499 void GenCollectedHeap::register_nmethod(nmethod* nm) {
500 CodeCache::register_scavenge_root_nmethod(nm);
501 }
502
503 void GenCollectedHeap::verify_nmethod(nmethod* nm) {
504 CodeCache::verify_scavenge_root_nmethod(nm);
505 }
506
507 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
508 return gen_policy()->satisfy_failed_allocation(size, is_tlab);
509 }
510
511 #ifdef ASSERT
512 class AssertNonScavengableClosure: public OopClosure {
513 public:
514 virtual void do_oop(oop* p) {
515 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
516 "Referent should not be scavengable."); }
517 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
518 };
519 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
520 #endif
521
522 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
523 ScanningOption so,
524 OopClosure* strong_roots,
525 OopClosure* weak_roots,
526 CLDClosure* strong_cld_closure,
527 CLDClosure* weak_cld_closure,
528 CodeBlobToOopClosure* code_roots) {
529 // General roots.
530 assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
531 assert(code_roots != NULL, "code root closure should always be set");
532 // _n_termination for _process_strong_tasks should be set up stream
533 // in a method not running in a GC worker. Otherwise the GC worker
534 // could be trying to change the termination condition while the task
535 // is executing in another GC worker.
536
537 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
538 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
539 }
540
541 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
542 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
543
544 bool is_par = scope->n_threads() > 1;
545 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p);
546
547 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
548 Universe::oops_do(strong_roots);
549 }
550 // Global (strong) JNI handles
551 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
552 JNIHandles::oops_do(strong_roots);
553 }
554
555 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
556 ObjectSynchronizer::oops_do(strong_roots);
557 }
558 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
559 Management::oops_do(strong_roots);
560 }
561 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
562 JvmtiExport::oops_do(strong_roots);
563 }
564 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) {
565 AOTLoader::oops_do(strong_roots);
566 }
567
568 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
569 SystemDictionary::roots_oops_do(strong_roots, weak_roots);
570 }
571
572 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
573 if (so & SO_ScavengeCodeCache) {
574 assert(code_roots != NULL, "must supply closure for code cache");
575
576 // We only visit parts of the CodeCache when scavenging.
577 CodeCache::scavenge_root_nmethods_do(code_roots);
578 }
579 if (so & SO_AllCodeCache) {
580 assert(code_roots != NULL, "must supply closure for code cache");
581
582 // CMSCollector uses this to do intermediate-strength collections.
583 // We scan the entire code cache, since CodeCache::do_unloading is not called.
584 CodeCache::blobs_do(code_roots);
585 }
586 // Verify that the code cache contents are not subject to
587 // movement by a scavenging collection.
588 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
589 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
590 }
591 }
592
593 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope,
594 OopClosure* root_closure) {
595 assert(root_closure != NULL, "Must be set");
596 // All threads execute the following. A specific chunk of buckets
597 // from the StringTable are the individual tasks.
598 if (scope->n_threads() > 1) {
599 StringTable::possibly_parallel_oops_do(root_closure);
600 } else {
601 StringTable::oops_do(root_closure);
602 }
603 }
604
605 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope,
606 OopsInGenClosure* root_closure,
607 OopsInGenClosure* old_gen_closure,
608 CLDClosure* cld_closure) {
609 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations);
610
611 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure,
612 cld_closure, cld_closure, &mark_code_closure);
613 process_string_table_roots(scope, root_closure);
614
615 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
616 root_closure->reset_generation();
617 }
618
619 // When collection is parallel, all threads get to cooperate to do
620 // old generation scanning.
621 old_gen_closure->set_generation(_old_gen);
622 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads());
623 old_gen_closure->reset_generation();
624
625 _process_strong_tasks->all_tasks_completed(scope->n_threads());
626 }
627
628 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope,
629 bool is_adjust_phase,
630 ScanningOption so,
631 bool only_strong_roots,
632 OopsInGenClosure* root_closure,
633 CLDClosure* cld_closure) {
634 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase);
635 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure;
636 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
637
638 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure);
639 if (is_adjust_phase) {
640 // We never treat the string table as roots during marking
641 // for the full gc, so we only need to process it during
642 // the adjust phase.
643 process_string_table_roots(scope, root_closure);
644 }
645
646 _process_strong_tasks->all_tasks_completed(scope->n_threads());
647 }
648
649 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
650 WeakProcessor::oops_do(root_closure);
651 _young_gen->ref_processor()->weak_oops_do(root_closure);
652 _old_gen->ref_processor()->weak_oops_do(root_closure);
653 }
654
655 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \
656 void GenCollectedHeap:: \
657 oop_since_save_marks_iterate(GenerationType gen, \
658 OopClosureType* cur, \
659 OopClosureType* older) { \
660 if (gen == YoungGen) { \
661 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
662 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \
663 } else { \
664 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \
665 } \
666 }
667
668 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
669
670 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
671
672 bool GenCollectedHeap::no_allocs_since_save_marks() {
673 return _young_gen->no_allocs_since_save_marks() &&
674 _old_gen->no_allocs_since_save_marks();
675 }
676
677 bool GenCollectedHeap::supports_inline_contig_alloc() const {
678 return _young_gen->supports_inline_contig_alloc();
679 }
680
681 HeapWord* volatile* GenCollectedHeap::top_addr() const {
682 return _young_gen->top_addr();
683 }
684
685 HeapWord** GenCollectedHeap::end_addr() const {
686 return _young_gen->end_addr();
687 }
688
689 // public collection interfaces
690
691 void GenCollectedHeap::collect(GCCause::Cause cause) {
692 if (cause == GCCause::_wb_young_gc) {
693 // Young collection for the WhiteBox API.
694 collect(cause, YoungGen);
695 } else {
696 #ifdef ASSERT
697 if (cause == GCCause::_scavenge_alot) {
698 // Young collection only.
699 collect(cause, YoungGen);
700 } else {
701 // Stop-the-world full collection.
702 collect(cause, OldGen);
703 }
704 #else
705 // Stop-the-world full collection.
706 collect(cause, OldGen);
707 #endif
708 }
709 }
710
711 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
712 // The caller doesn't have the Heap_lock
713 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
714 MutexLocker ml(Heap_lock);
715 collect_locked(cause, max_generation);
716 }
717
718 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
719 // The caller has the Heap_lock
720 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
721 collect_locked(cause, OldGen);
722 }
723
724 // this is the private collection interface
725 // The Heap_lock is expected to be held on entry.
726
727 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
728 // Read the GC count while holding the Heap_lock
729 unsigned int gc_count_before = total_collections();
730 unsigned int full_gc_count_before = total_full_collections();
731 {
732 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back
733 VM_GenCollectFull op(gc_count_before, full_gc_count_before,
734 cause, max_generation);
735 VMThread::execute(&op);
736 }
737 }
738
739 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
740 do_full_collection(clear_all_soft_refs, OldGen);
741 }
742
743 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
744 GenerationType last_generation) {
745 GenerationType local_last_generation;
746 if (!incremental_collection_will_fail(false /* don't consult_young */) &&
747 gc_cause() == GCCause::_gc_locker) {
748 local_last_generation = YoungGen;
749 } else {
750 local_last_generation = last_generation;
751 }
752
753 do_collection(true, // full
754 clear_all_soft_refs, // clear_all_soft_refs
755 0, // size
756 false, // is_tlab
757 local_last_generation); // last_generation
758 // Hack XXX FIX ME !!!
759 // A scavenge may not have been attempted, or may have
760 // been attempted and failed, because the old gen was too full
761 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
762 incremental_collection_will_fail(false /* don't consult_young */)) {
763 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed");
764 // This time allow the old gen to be collected as well
765 do_collection(true, // full
766 clear_all_soft_refs, // clear_all_soft_refs
767 0, // size
768 false, // is_tlab
769 OldGen); // last_generation
770 }
771 }
772
773 bool GenCollectedHeap::is_in_young(oop p) {
774 bool result = ((HeapWord*)p) < _old_gen->reserved().start();
775 assert(result == _young_gen->is_in_reserved(p),
776 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p));
777 return result;
778 }
779
780 // Returns "TRUE" iff "p" points into the committed areas of the heap.
781 bool GenCollectedHeap::is_in(const void* p) const {
782 return _young_gen->is_in(p) || _old_gen->is_in(p);
783 }
784
785 #ifdef ASSERT
786 // Don't implement this by using is_in_young(). This method is used
787 // in some cases to check that is_in_young() is correct.
788 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
789 assert(is_in_reserved(p) || p == NULL,
790 "Does not work if address is non-null and outside of the heap");
791 return p < _young_gen->reserved().end() && p != NULL;
792 }
793 #endif
794
795 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
796 NoHeaderExtendedOopClosure no_header_cl(cl);
797 oop_iterate(&no_header_cl);
798 }
799
800 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
801 _young_gen->oop_iterate(cl);
802 _old_gen->oop_iterate(cl);
803 }
804
805 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
806 _young_gen->object_iterate(cl);
807 _old_gen->object_iterate(cl);
808 }
809
810 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
811 _young_gen->safe_object_iterate(cl);
812 _old_gen->safe_object_iterate(cl);
813 }
814
815 Space* GenCollectedHeap::space_containing(const void* addr) const {
816 Space* res = _young_gen->space_containing(addr);
817 if (res != NULL) {
818 return res;
819 }
820 res = _old_gen->space_containing(addr);
821 assert(res != NULL, "Could not find containing space");
822 return res;
823 }
824
825 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
826 assert(is_in_reserved(addr), "block_start of address outside of heap");
827 if (_young_gen->is_in_reserved(addr)) {
828 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
829 return _young_gen->block_start(addr);
830 }
831
832 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
833 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
834 return _old_gen->block_start(addr);
835 }
836
837 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
838 assert(is_in_reserved(addr), "block_size of address outside of heap");
839 if (_young_gen->is_in_reserved(addr)) {
840 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
841 return _young_gen->block_size(addr);
842 }
843
844 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
845 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
846 return _old_gen->block_size(addr);
847 }
848
849 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
850 assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
851 assert(block_start(addr) == addr, "addr must be a block start");
852 if (_young_gen->is_in_reserved(addr)) {
853 return _young_gen->block_is_obj(addr);
854 }
855
856 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
857 return _old_gen->block_is_obj(addr);
858 }
859
860 bool GenCollectedHeap::supports_tlab_allocation() const {
861 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
862 return _young_gen->supports_tlab_allocation();
863 }
864
865 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
866 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
867 if (_young_gen->supports_tlab_allocation()) {
868 return _young_gen->tlab_capacity();
869 }
870 return 0;
871 }
872
873 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
874 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
875 if (_young_gen->supports_tlab_allocation()) {
876 return _young_gen->tlab_used();
877 }
878 return 0;
879 }
880
881 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
882 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
883 if (_young_gen->supports_tlab_allocation()) {
884 return _young_gen->unsafe_max_tlab_alloc();
885 }
886 return 0;
887 }
888
889 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
890 bool gc_overhead_limit_was_exceeded;
891 return gen_policy()->mem_allocate_work(size /* size */,
892 true /* is_tlab */,
893 &gc_overhead_limit_was_exceeded);
894 }
895
896 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size
897 // from the list headed by "*prev_ptr".
898 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
899 bool first = true;
900 size_t min_size = 0; // "first" makes this conceptually infinite.
901 ScratchBlock **smallest_ptr, *smallest;
902 ScratchBlock *cur = *prev_ptr;
903 while (cur) {
904 assert(*prev_ptr == cur, "just checking");
905 if (first || cur->num_words < min_size) {
906 smallest_ptr = prev_ptr;
907 smallest = cur;
908 min_size = smallest->num_words;
909 first = false;
910 }
911 prev_ptr = &cur->next;
912 cur = cur->next;
913 }
914 smallest = *smallest_ptr;
915 *smallest_ptr = smallest->next;
916 return smallest;
917 }
918
919 // Sort the scratch block list headed by res into decreasing size order,
920 // and set "res" to the result.
921 static void sort_scratch_list(ScratchBlock*& list) {
922 ScratchBlock* sorted = NULL;
923 ScratchBlock* unsorted = list;
924 while (unsorted) {
925 ScratchBlock *smallest = removeSmallestScratch(&unsorted);
926 smallest->next = sorted;
927 sorted = smallest;
928 }
929 list = sorted;
930 }
931
932 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
933 size_t max_alloc_words) {
934 ScratchBlock* res = NULL;
935 _young_gen->contribute_scratch(res, requestor, max_alloc_words);
936 _old_gen->contribute_scratch(res, requestor, max_alloc_words);
937 sort_scratch_list(res);
938 return res;
939 }
940
941 void GenCollectedHeap::release_scratch() {
942 _young_gen->reset_scratch();
943 _old_gen->reset_scratch();
944 }
945
946 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
947 void do_generation(Generation* gen) {
948 gen->prepare_for_verify();
949 }
950 };
951
952 void GenCollectedHeap::prepare_for_verify() {
953 ensure_parsability(false); // no need to retire TLABs
954 GenPrepareForVerifyClosure blk;
955 generation_iterate(&blk, false);
956 }
957
958 void GenCollectedHeap::generation_iterate(GenClosure* cl,
959 bool old_to_young) {
960 if (old_to_young) {
961 cl->do_generation(_old_gen);
962 cl->do_generation(_young_gen);
963 } else {
964 cl->do_generation(_young_gen);
965 cl->do_generation(_old_gen);
966 }
967 }
968
969 bool GenCollectedHeap::is_maximal_no_gc() const {
970 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
971 }
972
973 void GenCollectedHeap::save_marks() {
974 _young_gen->save_marks();
975 _old_gen->save_marks();
976 }
977
978 GenCollectedHeap* GenCollectedHeap::heap() {
979 CollectedHeap* heap = Universe::heap();
980 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
981 assert(heap->kind() == CollectedHeap::SerialHeap ||
982 heap->kind() == CollectedHeap::CMSHeap, "Not a GenCollectedHeap");
983 return (GenCollectedHeap*) heap;
984 }
985
986 void GenCollectedHeap::prepare_for_compaction() {
987 // Start by compacting into same gen.
988 CompactPoint cp(_old_gen);
989 _old_gen->prepare_for_compaction(&cp);
990 _young_gen->prepare_for_compaction(&cp);
991 }
992
993 void GenCollectedHeap::verify(VerifyOption option /* ignored */) {
994 log_debug(gc, verify)("%s", _old_gen->name());
995 _old_gen->verify();
996
997 log_debug(gc, verify)("%s", _old_gen->name());
998 _young_gen->verify();
999
1000 log_debug(gc, verify)("RemSet");
1001 rem_set()->verify();
1002 }
1003
1004 void GenCollectedHeap::print_on(outputStream* st) const {
1005 _young_gen->print_on(st);
1006 _old_gen->print_on(st);
1007 MetaspaceAux::print_on(st);
1008 }
1009
1010 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1011 }
1012
1013 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1014 }
1015
1016 void GenCollectedHeap::print_tracing_info() const {
1017 if (log_is_enabled(Debug, gc, heap, exit)) {
1018 LogStreamHandle(Debug, gc, heap, exit) lsh;
1019 _young_gen->print_summary_info_on(&lsh);
1020 _old_gen->print_summary_info_on(&lsh);
1021 }
1022 }
1023
1024 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const {
1025 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1026 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K);
1027 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)",
1028 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K);
1029 }
1030
1031 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1032 private:
1033 bool _full;
1034 public:
1035 void do_generation(Generation* gen) {
1036 gen->gc_prologue(_full);
1037 }
1038 GenGCPrologueClosure(bool full) : _full(full) {};
1039 };
1040
1041 void GenCollectedHeap::gc_prologue(bool full) {
1042 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1043
1044 // Fill TLAB's and such
1045 CollectedHeap::accumulate_statistics_all_tlabs();
1046 ensure_parsability(true); // retire TLABs
1047
1048 // Walk generations
1049 GenGCPrologueClosure blk(full);
1050 generation_iterate(&blk, false); // not old-to-young.
1051 };
1052
1053 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1054 private:
1055 bool _full;
1056 public:
1057 void do_generation(Generation* gen) {
1058 gen->gc_epilogue(_full);
1059 }
1060 GenGCEpilogueClosure(bool full) : _full(full) {};
1061 };
1062
1063 void GenCollectedHeap::gc_epilogue(bool full) {
1064 #if COMPILER2_OR_JVMCI
1065 assert(DerivedPointerTable::is_empty(), "derived pointer present");
1066 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1067 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1068 #endif // COMPILER2_OR_JVMCI
1069
1070 resize_all_tlabs();
1071
1072 GenGCEpilogueClosure blk(full);
1073 generation_iterate(&blk, false); // not old-to-young.
1074
1075 if (!CleanChunkPoolAsync) {
1076 Chunk::clean_chunk_pool();
1077 }
1078
1079 MetaspaceCounters::update_performance_counters();
1080 CompressedClassSpaceCounters::update_performance_counters();
1081 };
1082
1083 #ifndef PRODUCT
1084 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1085 private:
1086 public:
1087 void do_generation(Generation* gen) {
1088 gen->record_spaces_top();
1089 }
1090 };
1091
1092 void GenCollectedHeap::record_gen_tops_before_GC() {
1093 if (ZapUnusedHeapArea) {
1094 GenGCSaveTopsBeforeGCClosure blk;
1095 generation_iterate(&blk, false); // not old-to-young.
1096 }
1097 }
1098 #endif // not PRODUCT
1099
1100 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1101 public:
1102 void do_generation(Generation* gen) {
1103 gen->ensure_parsability();
1104 }
1105 };
1106
1107 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1108 CollectedHeap::ensure_parsability(retire_tlabs);
1109 GenEnsureParsabilityClosure ep_cl;
1110 generation_iterate(&ep_cl, false);
1111 }
1112
1113 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1114 oop obj,
1115 size_t obj_size) {
1116 guarantee(old_gen == _old_gen, "We only get here with an old generation");
1117 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1118 HeapWord* result = NULL;
1119
1120 result = old_gen->expand_and_allocate(obj_size, false);
1121
1122 if (result != NULL) {
1123 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1124 }
1125 return oop(result);
1126 }
1127
1128 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1129 jlong _time; // in ms
1130 jlong _now; // in ms
1131
1132 public:
1133 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1134
1135 jlong time() { return _time; }
1136
1137 void do_generation(Generation* gen) {
1138 _time = MIN2(_time, gen->time_of_last_gc(_now));
1139 }
1140 };
1141
1142 jlong GenCollectedHeap::millis_since_last_gc() {
1143 // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1144 // provided the underlying platform provides such a time source
1145 // (and it is bug free). So we still have to guard against getting
1146 // back a time later than 'now'.
1147 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1148 GenTimeOfLastGCClosure tolgc_cl(now);
1149 // iterate over generations getting the oldest
1150 // time that a generation was collected
1151 generation_iterate(&tolgc_cl, false);
1152
1153 jlong retVal = now - tolgc_cl.time();
1154 if (retVal < 0) {
1155 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT
1156 ". returning zero instead.", retVal);
1157 return 0;
1158 }
1159 return retVal;
1160 }