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