1 /* 2 * Copyright (c) 2000, 2015, 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 "classfile/symbolTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/shared/collectedHeap.inline.hpp" 32 #include "gc/shared/collectorCounters.hpp" 33 #include "gc/shared/gcLocker.inline.hpp" 34 #include "gc/shared/gcTrace.hpp" 35 #include "gc/shared/gcTraceTime.hpp" 36 #include "gc/shared/genCollectedHeap.hpp" 37 #include "gc/shared/genOopClosures.inline.hpp" 38 #include "gc/shared/generationSpec.hpp" 39 #include "gc/shared/space.hpp" 40 #include "gc/shared/strongRootsScope.hpp" 41 #include "gc/shared/vmGCOperations.hpp" 42 #include "gc/shared/workgroup.hpp" 43 #include "memory/filemap.hpp" 44 #include "memory/resourceArea.hpp" 45 #include "oops/oop.inline.hpp" 46 #include "runtime/biasedLocking.hpp" 47 #include "runtime/fprofiler.hpp" 48 #include "runtime/handles.hpp" 49 #include "runtime/handles.inline.hpp" 50 #include "runtime/java.hpp" 51 #include "runtime/vmThread.hpp" 52 #include "services/management.hpp" 53 #include "services/memoryService.hpp" 54 #include "utilities/macros.hpp" 55 #include "utilities/stack.inline.hpp" 56 #include "utilities/vmError.hpp" 57 #if INCLUDE_ALL_GCS 58 #include "gc/cms/concurrentMarkSweepThread.hpp" 59 #include "gc/cms/vmCMSOperations.hpp" 60 #endif // INCLUDE_ALL_GCS 61 62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;) 63 64 // The set of potentially parallel tasks in root scanning. 65 enum GCH_strong_roots_tasks { 66 GCH_PS_Universe_oops_do, 67 GCH_PS_JNIHandles_oops_do, 68 GCH_PS_ObjectSynchronizer_oops_do, 69 GCH_PS_FlatProfiler_oops_do, 70 GCH_PS_Management_oops_do, 71 GCH_PS_SystemDictionary_oops_do, 72 GCH_PS_ClassLoaderDataGraph_oops_do, 73 GCH_PS_jvmti_oops_do, 74 GCH_PS_CodeCache_oops_do, 75 GCH_PS_younger_gens, 76 // Leave this one last. 77 GCH_PS_NumElements 78 }; 79 80 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) : 81 CollectedHeap(), 82 _rem_set(NULL), 83 _gen_policy(policy), 84 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)), 85 _full_collections_completed(0) 86 { 87 assert(policy != NULL, "Sanity check"); 88 if (UseConcMarkSweepGC) { 89 _workers = new WorkGang("GC Thread", ParallelGCThreads, 90 /* are_GC_task_threads */true, 91 /* are_ConcurrentGC_threads */false); 92 _workers->initialize_workers(); 93 } else { 94 // Serial GC does not use workers. 95 _workers = NULL; 96 } 97 } 98 99 jint GenCollectedHeap::initialize() { 100 CollectedHeap::pre_initialize(); 101 102 // While there are no constraints in the GC code that HeapWordSize 103 // be any particular value, there are multiple other areas in the 104 // system which believe this to be true (e.g. oop->object_size in some 105 // cases incorrectly returns the size in wordSize units rather than 106 // HeapWordSize). 107 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 108 109 // Allocate space for the heap. 110 111 char* heap_address; 112 ReservedSpace heap_rs; 113 114 size_t heap_alignment = collector_policy()->heap_alignment(); 115 116 heap_address = allocate(heap_alignment, &heap_rs); 117 118 if (!heap_rs.is_reserved()) { 119 vm_shutdown_during_initialization( 120 "Could not reserve enough space for object heap"); 121 return JNI_ENOMEM; 122 } 123 124 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 125 126 _rem_set = collector_policy()->create_rem_set(reserved_region()); 127 set_barrier_set(rem_set()->bs()); 128 129 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false); 130 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set()); 131 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size()); 132 133 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false); 134 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set()); 135 clear_incremental_collection_failed(); 136 137 #if INCLUDE_ALL_GCS 138 // If we are running CMS, create the collector responsible 139 // for collecting the CMS generations. 140 if (collector_policy()->is_concurrent_mark_sweep_policy()) { 141 bool success = create_cms_collector(); 142 if (!success) return JNI_ENOMEM; 143 } 144 #endif // INCLUDE_ALL_GCS 145 146 return JNI_OK; 147 } 148 149 char* GenCollectedHeap::allocate(size_t alignment, 150 ReservedSpace* heap_rs){ 151 // Now figure out the total size. 152 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 153 assert(alignment % pageSize == 0, "Must be"); 154 155 GenerationSpec* young_spec = gen_policy()->young_gen_spec(); 156 GenerationSpec* old_spec = gen_policy()->old_gen_spec(); 157 158 // Check for overflow. 159 size_t total_reserved = young_spec->max_size() + old_spec->max_size(); 160 if (total_reserved < young_spec->max_size()) { 161 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 162 "the maximum representable size"); 163 } 164 assert(total_reserved % alignment == 0, 165 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 166 SIZE_FORMAT, total_reserved, alignment)); 167 168 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 169 return heap_rs->base(); 170 } 171 172 void GenCollectedHeap::post_initialize() { 173 CollectedHeap::post_initialize(); 174 ref_processing_init(); 175 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy(); 176 guarantee(policy->is_generation_policy(), "Illegal policy type"); 177 assert((_young_gen->kind() == Generation::DefNew) || 178 (_young_gen->kind() == Generation::ParNew), 179 "Wrong youngest generation type"); 180 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 181 182 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep || 183 _old_gen->kind() == Generation::MarkSweepCompact, 184 "Wrong generation kind"); 185 186 policy->initialize_size_policy(def_new_gen->eden()->capacity(), 187 _old_gen->capacity(), 188 def_new_gen->from()->capacity()); 189 policy->initialize_gc_policy_counters(); 190 } 191 192 void GenCollectedHeap::ref_processing_init() { 193 _young_gen->ref_processor_init(); 194 _old_gen->ref_processor_init(); 195 } 196 197 size_t GenCollectedHeap::capacity() const { 198 return _young_gen->capacity() + _old_gen->capacity(); 199 } 200 201 size_t GenCollectedHeap::used() const { 202 return _young_gen->used() + _old_gen->used(); 203 } 204 205 void GenCollectedHeap::save_used_regions() { 206 _old_gen->save_used_region(); 207 _young_gen->save_used_region(); 208 } 209 210 size_t GenCollectedHeap::max_capacity() const { 211 return _young_gen->max_capacity() + _old_gen->max_capacity(); 212 } 213 214 // Update the _full_collections_completed counter 215 // at the end of a stop-world full GC. 216 unsigned int GenCollectedHeap::update_full_collections_completed() { 217 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 218 assert(_full_collections_completed <= _total_full_collections, 219 "Can't complete more collections than were started"); 220 _full_collections_completed = _total_full_collections; 221 ml.notify_all(); 222 return _full_collections_completed; 223 } 224 225 // Update the _full_collections_completed counter, as appropriate, 226 // at the end of a concurrent GC cycle. Note the conditional update 227 // below to allow this method to be called by a concurrent collector 228 // without synchronizing in any manner with the VM thread (which 229 // may already have initiated a STW full collection "concurrently"). 230 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 231 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 232 assert((_full_collections_completed <= _total_full_collections) && 233 (count <= _total_full_collections), 234 "Can't complete more collections than were started"); 235 if (count > _full_collections_completed) { 236 _full_collections_completed = count; 237 ml.notify_all(); 238 } 239 return _full_collections_completed; 240 } 241 242 243 #ifndef PRODUCT 244 // Override of memory state checking method in CollectedHeap: 245 // Some collectors (CMS for example) can't have badHeapWordVal written 246 // in the first two words of an object. (For instance , in the case of 247 // CMS these words hold state used to synchronize between certain 248 // (concurrent) GC steps and direct allocating mutators.) 249 // The skip_header_HeapWords() method below, allows us to skip 250 // over the requisite number of HeapWord's. Note that (for 251 // generational collectors) this means that those many words are 252 // skipped in each object, irrespective of the generation in which 253 // that object lives. The resultant loss of precision seems to be 254 // harmless and the pain of avoiding that imprecision appears somewhat 255 // higher than we are prepared to pay for such rudimentary debugging 256 // support. 257 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 258 size_t size) { 259 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 260 // We are asked to check a size in HeapWords, 261 // but the memory is mangled in juint words. 262 juint* start = (juint*) (addr + skip_header_HeapWords()); 263 juint* end = (juint*) (addr + size); 264 for (juint* slot = start; slot < end; slot += 1) { 265 assert(*slot == badHeapWordVal, 266 "Found non badHeapWordValue in pre-allocation check"); 267 } 268 } 269 } 270 #endif 271 272 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 273 bool is_tlab, 274 bool first_only) { 275 HeapWord* res = NULL; 276 277 if (_young_gen->should_allocate(size, is_tlab)) { 278 res = _young_gen->allocate(size, is_tlab); 279 if (res != NULL || first_only) { 280 return res; 281 } 282 } 283 284 if (_old_gen->should_allocate(size, is_tlab)) { 285 res = _old_gen->allocate(size, is_tlab); 286 } 287 288 return res; 289 } 290 291 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 292 bool* gc_overhead_limit_was_exceeded) { 293 return collector_policy()->mem_allocate_work(size, 294 false /* is_tlab */, 295 gc_overhead_limit_was_exceeded); 296 } 297 298 bool GenCollectedHeap::must_clear_all_soft_refs() { 299 return _gc_cause == GCCause::_last_ditch_collection; 300 } 301 302 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 303 if (!UseConcMarkSweepGC) { 304 return false; 305 } 306 307 switch (cause) { 308 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 309 case GCCause::_java_lang_system_gc: 310 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 311 default: return false; 312 } 313 } 314 315 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 316 bool is_tlab, bool run_verification, bool clear_soft_refs, 317 bool restore_marks_for_biased_locking) { 318 // Timer for individual generations. Last argument is false: no CR 319 // FIXME: We should try to start the timing earlier to cover more of the GC pause 320 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 321 // so we can assume here that the next GC id is what we want. 322 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek()); 323 TraceCollectorStats tcs(gen->counters()); 324 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 325 326 size_t prev_used = gen->used(); 327 gen->stat_record()->invocations++; 328 gen->stat_record()->accumulated_time.start(); 329 330 // Must be done anew before each collection because 331 // a previous collection will do mangling and will 332 // change top of some spaces. 333 record_gen_tops_before_GC(); 334 335 if (PrintGC && Verbose) { 336 // I didn't want to change the logging when removing the level concept, 337 // but I guess this logging could say young/old or something instead of 0/1. 338 uint level; 339 if (heap()->is_young_gen(gen)) { 340 level = 0; 341 } else { 342 level = 1; 343 } 344 gclog_or_tty->print("level=%u invoke=%d size=" SIZE_FORMAT, 345 level, 346 gen->stat_record()->invocations, 347 size * HeapWordSize); 348 } 349 350 if (run_verification && VerifyBeforeGC) { 351 HandleMark hm; // Discard invalid handles created during verification 352 Universe::verify(" VerifyBeforeGC:"); 353 } 354 COMPILER2_PRESENT(DerivedPointerTable::clear()); 355 356 if (restore_marks_for_biased_locking) { 357 // We perform this mark word preservation work lazily 358 // because it's only at this point that we know whether we 359 // absolutely have to do it; we want to avoid doing it for 360 // scavenge-only collections where it's unnecessary 361 BiasedLocking::preserve_marks(); 362 } 363 364 // Do collection work 365 { 366 // Note on ref discovery: For what appear to be historical reasons, 367 // GCH enables and disabled (by enqueing) refs discovery. 368 // In the future this should be moved into the generation's 369 // collect method so that ref discovery and enqueueing concerns 370 // are local to a generation. The collect method could return 371 // an appropriate indication in the case that notification on 372 // the ref lock was needed. This will make the treatment of 373 // weak refs more uniform (and indeed remove such concerns 374 // from GCH). XXX 375 376 HandleMark hm; // Discard invalid handles created during gc 377 save_marks(); // save marks for all gens 378 // We want to discover references, but not process them yet. 379 // This mode is disabled in process_discovered_references if the 380 // generation does some collection work, or in 381 // enqueue_discovered_references if the generation returns 382 // without doing any work. 383 ReferenceProcessor* rp = gen->ref_processor(); 384 // If the discovery of ("weak") refs in this generation is 385 // atomic wrt other collectors in this configuration, we 386 // are guaranteed to have empty discovered ref lists. 387 if (rp->discovery_is_atomic()) { 388 rp->enable_discovery(); 389 rp->setup_policy(clear_soft_refs); 390 } else { 391 // collect() below will enable discovery as appropriate 392 } 393 gen->collect(full, clear_soft_refs, size, is_tlab); 394 if (!rp->enqueuing_is_done()) { 395 rp->enqueue_discovered_references(); 396 } else { 397 rp->set_enqueuing_is_done(false); 398 } 399 rp->verify_no_references_recorded(); 400 } 401 402 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 403 404 gen->stat_record()->accumulated_time.stop(); 405 406 update_gc_stats(gen, full); 407 408 if (run_verification && VerifyAfterGC) { 409 HandleMark hm; // Discard invalid handles created during verification 410 Universe::verify(" VerifyAfterGC:"); 411 } 412 413 if (PrintGCDetails) { 414 gclog_or_tty->print(":"); 415 gen->print_heap_change(prev_used); 416 } 417 } 418 419 void GenCollectedHeap::do_collection(bool full, 420 bool clear_all_soft_refs, 421 size_t size, 422 bool is_tlab, 423 GenerationType max_generation) { 424 ResourceMark rm; 425 DEBUG_ONLY(Thread* my_thread = Thread::current();) 426 427 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 428 assert(my_thread->is_VM_thread() || 429 my_thread->is_ConcurrentGC_thread(), 430 "incorrect thread type capability"); 431 assert(Heap_lock->is_locked(), 432 "the requesting thread should have the Heap_lock"); 433 guarantee(!is_gc_active(), "collection is not reentrant"); 434 435 if (GC_locker::check_active_before_gc()) { 436 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 437 } 438 439 const bool do_clear_all_soft_refs = clear_all_soft_refs || 440 collector_policy()->should_clear_all_soft_refs(); 441 442 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 443 444 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 445 446 print_heap_before_gc(); 447 448 { 449 FlagSetting fl(_is_gc_active, true); 450 451 bool complete = full && (max_generation == OldGen); 452 const char* gc_cause_prefix = complete ? "Full GC" : "GC"; 453 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 454 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 455 // so we can assume here that the next GC id is what we want. 456 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek()); 457 458 gc_prologue(complete); 459 increment_total_collections(complete); 460 461 size_t gch_prev_used = used(); 462 bool run_verification = total_collections() >= VerifyGCStartAt; 463 464 bool prepared_for_verification = false; 465 bool collected_old = false; 466 bool old_collects_young = complete && !ScavengeBeforeFullGC; 467 468 if (!old_collects_young && _young_gen->should_collect(full, size, is_tlab)) { 469 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 470 prepare_for_verify(); 471 prepared_for_verification = true; 472 } 473 474 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking"); 475 collect_generation(_young_gen, 476 full, 477 size, 478 is_tlab, 479 run_verification && VerifyGCLevel <= 0, 480 do_clear_all_soft_refs, 481 false); 482 483 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 484 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 485 // Allocation request was met by young GC. 486 size = 0; 487 } 488 } 489 490 bool must_restore_marks_for_biased_locking = false; 491 492 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 493 if (!complete) { 494 // The full_collections increment was missed above. 495 increment_total_full_collections(); 496 } 497 498 pre_full_gc_dump(NULL); // do any pre full gc dumps 499 500 if (!prepared_for_verification && run_verification && 501 VerifyGCLevel <= 1 && VerifyBeforeGC) { 502 prepare_for_verify(); 503 } 504 505 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking"); 506 collect_generation(_old_gen, 507 full, 508 size, 509 is_tlab, 510 run_verification && VerifyGCLevel <= 1, 511 do_clear_all_soft_refs, 512 true); 513 514 must_restore_marks_for_biased_locking = true; 515 collected_old = true; 516 } 517 518 // Update "complete" boolean wrt what actually transpired -- 519 // for instance, a promotion failure could have led to 520 // a whole heap collection. 521 complete = complete || collected_old; 522 523 if (complete) { // We did a full collection 524 // FIXME: See comment at pre_full_gc_dump call 525 post_full_gc_dump(NULL); // do any post full gc dumps 526 } 527 528 if (PrintGCDetails) { 529 print_heap_change(gch_prev_used); 530 531 // Print metaspace info for full GC with PrintGCDetails flag. 532 if (complete) { 533 MetaspaceAux::print_metaspace_change(metadata_prev_used); 534 } 535 } 536 537 // Adjust generation sizes. 538 if (collected_old) { 539 _old_gen->compute_new_size(); 540 } 541 _young_gen->compute_new_size(); 542 543 if (complete) { 544 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 545 ClassLoaderDataGraph::purge(); 546 MetaspaceAux::verify_metrics(); 547 // Resize the metaspace capacity after full collections 548 MetaspaceGC::compute_new_size(); 549 update_full_collections_completed(); 550 } 551 552 // Track memory usage and detect low memory after GC finishes 553 MemoryService::track_memory_usage(); 554 555 gc_epilogue(complete); 556 557 if (must_restore_marks_for_biased_locking) { 558 BiasedLocking::restore_marks(); 559 } 560 } 561 562 print_heap_after_gc(); 563 564 #ifdef TRACESPINNING 565 ParallelTaskTerminator::print_termination_counts(); 566 #endif 567 } 568 569 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 570 return collector_policy()->satisfy_failed_allocation(size, is_tlab); 571 } 572 573 #ifdef ASSERT 574 class AssertNonScavengableClosure: public OopClosure { 575 public: 576 virtual void do_oop(oop* p) { 577 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 578 "Referent should not be scavengable."); } 579 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 580 }; 581 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 582 #endif 583 584 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 585 ScanningOption so, 586 OopClosure* strong_roots, 587 OopClosure* weak_roots, 588 CLDClosure* strong_cld_closure, 589 CLDClosure* weak_cld_closure, 590 CodeBlobClosure* code_roots) { 591 // General roots. 592 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 593 assert(code_roots != NULL, "code root closure should always be set"); 594 // _n_termination for _process_strong_tasks should be set up stream 595 // in a method not running in a GC worker. Otherwise the GC worker 596 // could be trying to change the termination condition while the task 597 // is executing in another GC worker. 598 599 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 600 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 601 } 602 603 // Some CLDs contained in the thread frames should be considered strong. 604 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 605 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 606 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 607 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 608 609 bool is_par = scope->n_threads() > 1; 610 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p); 611 612 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 613 Universe::oops_do(strong_roots); 614 } 615 // Global (strong) JNI handles 616 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 617 JNIHandles::oops_do(strong_roots); 618 } 619 620 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 621 ObjectSynchronizer::oops_do(strong_roots); 622 } 623 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 624 FlatProfiler::oops_do(strong_roots); 625 } 626 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 627 Management::oops_do(strong_roots); 628 } 629 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 630 JvmtiExport::oops_do(strong_roots); 631 } 632 633 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 634 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 635 } 636 637 // All threads execute the following. A specific chunk of buckets 638 // from the StringTable are the individual tasks. 639 if (weak_roots != NULL) { 640 if (is_par) { 641 StringTable::possibly_parallel_oops_do(weak_roots); 642 } else { 643 StringTable::oops_do(weak_roots); 644 } 645 } 646 647 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 648 if (so & SO_ScavengeCodeCache) { 649 assert(code_roots != NULL, "must supply closure for code cache"); 650 651 // We only visit parts of the CodeCache when scavenging. 652 CodeCache::scavenge_root_nmethods_do(code_roots); 653 } 654 if (so & SO_AllCodeCache) { 655 assert(code_roots != NULL, "must supply closure for code cache"); 656 657 // CMSCollector uses this to do intermediate-strength collections. 658 // We scan the entire code cache, since CodeCache::do_unloading is not called. 659 CodeCache::blobs_do(code_roots); 660 } 661 // Verify that the code cache contents are not subject to 662 // movement by a scavenging collection. 663 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 664 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 665 } 666 } 667 668 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope, 669 OopsInGenClosure* young_gen_closure, 670 OopsInGenClosure* old_gen_closure, 671 CLDClosure* cld_closure) { 672 MarkingCodeBlobClosure mark_code_closure(young_gen_closure, true /* young collections are always moving */); 673 674 process_roots(scope, SO_ScavengeCodeCache, young_gen_closure, young_gen_closure, 675 cld_closure, cld_closure, &mark_code_closure); 676 677 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 678 young_gen_closure->reset_generation(); 679 } 680 681 // When collection is parallel, all threads get to cooperate to do 682 // old generation scanning. 683 old_gen_closure->set_generation(_old_gen); 684 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); 685 old_gen_closure->reset_generation(); 686 687 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 688 } 689 690 void GenCollectedHeap::old_process_roots(StrongRootsScope* scope, 691 bool young_gen_as_roots, 692 ScanningOption so, 693 bool only_strong_roots, 694 OopsInGenClosure* young_gen_closure, 695 CLDClosure* cld_closure) { 696 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots; 697 698 bool is_moving_collection = false; 699 if (is_adjust_phase) { 700 is_moving_collection = true; 701 } 702 703 MarkingCodeBlobClosure mark_code_closure(young_gen_closure, is_moving_collection); 704 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : young_gen_closure; 705 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 706 707 process_roots(scope, so, young_gen_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure); 708 709 if (young_gen_as_roots && 710 !_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 711 young_gen_closure->set_generation(_young_gen); 712 _young_gen->oop_iterate(young_gen_closure); 713 young_gen_closure->reset_generation(); 714 } 715 716 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 717 } 718 719 class AlwaysTrueClosure: public BoolObjectClosure { 720 public: 721 bool do_object_b(oop p) { return true; } 722 }; 723 static AlwaysTrueClosure always_true; 724 725 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 726 JNIHandles::weak_oops_do(&always_true, root_closure); 727 _young_gen->ref_processor()->weak_oops_do(root_closure); 728 _old_gen->ref_processor()->weak_oops_do(root_closure); 729 } 730 731 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 732 void GenCollectedHeap:: \ 733 oop_since_save_marks_iterate(GenerationType gen, \ 734 OopClosureType* cur, \ 735 OopClosureType* older) { \ 736 if (gen == YoungGen) { \ 737 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 738 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 739 } else { \ 740 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 741 } \ 742 } 743 744 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 745 746 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 747 748 bool GenCollectedHeap::no_allocs_since_save_marks() { 749 return _young_gen->no_allocs_since_save_marks() && 750 _old_gen->no_allocs_since_save_marks(); 751 } 752 753 bool GenCollectedHeap::supports_inline_contig_alloc() const { 754 return _young_gen->supports_inline_contig_alloc(); 755 } 756 757 HeapWord** GenCollectedHeap::top_addr() const { 758 return _young_gen->top_addr(); 759 } 760 761 HeapWord** GenCollectedHeap::end_addr() const { 762 return _young_gen->end_addr(); 763 } 764 765 // public collection interfaces 766 767 void GenCollectedHeap::collect(GCCause::Cause cause) { 768 if (should_do_concurrent_full_gc(cause)) { 769 #if INCLUDE_ALL_GCS 770 // Mostly concurrent full collection. 771 collect_mostly_concurrent(cause); 772 #else // INCLUDE_ALL_GCS 773 ShouldNotReachHere(); 774 #endif // INCLUDE_ALL_GCS 775 } else if (cause == GCCause::_wb_young_gc) { 776 // Young collection for the WhiteBox API. 777 collect(cause, YoungGen); 778 } else { 779 #ifdef ASSERT 780 if (cause == GCCause::_scavenge_alot) { 781 // Young collection only. 782 collect(cause, YoungGen); 783 } else { 784 // Stop-the-world full collection. 785 collect(cause, OldGen); 786 } 787 #else 788 // Stop-the-world full collection. 789 collect(cause, OldGen); 790 #endif 791 } 792 } 793 794 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 795 // The caller doesn't have the Heap_lock 796 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 797 MutexLocker ml(Heap_lock); 798 collect_locked(cause, max_generation); 799 } 800 801 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 802 // The caller has the Heap_lock 803 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 804 collect_locked(cause, OldGen); 805 } 806 807 // this is the private collection interface 808 // The Heap_lock is expected to be held on entry. 809 810 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 811 // Read the GC count while holding the Heap_lock 812 unsigned int gc_count_before = total_collections(); 813 unsigned int full_gc_count_before = total_full_collections(); 814 { 815 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 816 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 817 cause, max_generation); 818 VMThread::execute(&op); 819 } 820 } 821 822 #if INCLUDE_ALL_GCS 823 bool GenCollectedHeap::create_cms_collector() { 824 825 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 826 "Unexpected generation kinds"); 827 // Skip two header words in the block content verification 828 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 829 CMSCollector* collector = new CMSCollector( 830 (ConcurrentMarkSweepGeneration*)_old_gen, 831 _rem_set->as_CardTableRS(), 832 (ConcurrentMarkSweepPolicy*) collector_policy()); 833 834 if (collector == NULL || !collector->completed_initialization()) { 835 if (collector) { 836 delete collector; // Be nice in embedded situation 837 } 838 vm_shutdown_during_initialization("Could not create CMS collector"); 839 return false; 840 } 841 return true; // success 842 } 843 844 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 845 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 846 847 MutexLocker ml(Heap_lock); 848 // Read the GC counts while holding the Heap_lock 849 unsigned int full_gc_count_before = total_full_collections(); 850 unsigned int gc_count_before = total_collections(); 851 { 852 MutexUnlocker mu(Heap_lock); 853 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 854 VMThread::execute(&op); 855 } 856 } 857 #endif // INCLUDE_ALL_GCS 858 859 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 860 do_full_collection(clear_all_soft_refs, OldGen); 861 } 862 863 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 864 GenerationType last_generation) { 865 GenerationType local_last_generation; 866 if (!incremental_collection_will_fail(false /* don't consult_young */) && 867 gc_cause() == GCCause::_gc_locker) { 868 local_last_generation = YoungGen; 869 } else { 870 local_last_generation = last_generation; 871 } 872 873 do_collection(true, // full 874 clear_all_soft_refs, // clear_all_soft_refs 875 0, // size 876 false, // is_tlab 877 local_last_generation); // last_generation 878 // Hack XXX FIX ME !!! 879 // A scavenge may not have been attempted, or may have 880 // been attempted and failed, because the old gen was too full 881 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 882 incremental_collection_will_fail(false /* don't consult_young */)) { 883 if (PrintGCDetails) { 884 gclog_or_tty->print_cr("GC locker: Trying a full collection " 885 "because scavenge failed"); 886 } 887 // This time allow the old gen to be collected as well 888 do_collection(true, // full 889 clear_all_soft_refs, // clear_all_soft_refs 890 0, // size 891 false, // is_tlab 892 OldGen); // last_generation 893 } 894 } 895 896 bool GenCollectedHeap::is_in_young(oop p) { 897 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 898 assert(result == _young_gen->is_in_reserved(p), 899 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p))); 900 return result; 901 } 902 903 // Returns "TRUE" iff "p" points into the committed areas of the heap. 904 bool GenCollectedHeap::is_in(const void* p) const { 905 return _young_gen->is_in(p) || _old_gen->is_in(p); 906 } 907 908 #ifdef ASSERT 909 // Don't implement this by using is_in_young(). This method is used 910 // in some cases to check that is_in_young() is correct. 911 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 912 assert(is_in_reserved(p) || p == NULL, 913 "Does not work if address is non-null and outside of the heap"); 914 return p < _young_gen->reserved().end() && p != NULL; 915 } 916 #endif 917 918 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 919 NoHeaderExtendedOopClosure no_header_cl(cl); 920 oop_iterate(&no_header_cl); 921 } 922 923 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 924 _young_gen->oop_iterate(cl); 925 _old_gen->oop_iterate(cl); 926 } 927 928 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 929 _young_gen->object_iterate(cl); 930 _old_gen->object_iterate(cl); 931 } 932 933 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 934 _young_gen->safe_object_iterate(cl); 935 _old_gen->safe_object_iterate(cl); 936 } 937 938 Space* GenCollectedHeap::space_containing(const void* addr) const { 939 Space* res = _young_gen->space_containing(addr); 940 if (res != NULL) { 941 return res; 942 } 943 res = _old_gen->space_containing(addr); 944 assert(res != NULL, "Could not find containing space"); 945 return res; 946 } 947 948 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 949 assert(is_in_reserved(addr), "block_start of address outside of heap"); 950 if (_young_gen->is_in_reserved(addr)) { 951 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 952 return _young_gen->block_start(addr); 953 } 954 955 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 956 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 957 return _old_gen->block_start(addr); 958 } 959 960 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 961 assert(is_in_reserved(addr), "block_size of address outside of heap"); 962 if (_young_gen->is_in_reserved(addr)) { 963 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 964 return _young_gen->block_size(addr); 965 } 966 967 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 968 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 969 return _old_gen->block_size(addr); 970 } 971 972 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 973 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 974 assert(block_start(addr) == addr, "addr must be a block start"); 975 if (_young_gen->is_in_reserved(addr)) { 976 return _young_gen->block_is_obj(addr); 977 } 978 979 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 980 return _old_gen->block_is_obj(addr); 981 } 982 983 bool GenCollectedHeap::supports_tlab_allocation() const { 984 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 985 return _young_gen->supports_tlab_allocation(); 986 } 987 988 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 989 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 990 if (_young_gen->supports_tlab_allocation()) { 991 return _young_gen->tlab_capacity(); 992 } 993 return 0; 994 } 995 996 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 997 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 998 if (_young_gen->supports_tlab_allocation()) { 999 return _young_gen->tlab_used(); 1000 } 1001 return 0; 1002 } 1003 1004 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 1005 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1006 if (_young_gen->supports_tlab_allocation()) { 1007 return _young_gen->unsafe_max_tlab_alloc(); 1008 } 1009 return 0; 1010 } 1011 1012 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 1013 bool gc_overhead_limit_was_exceeded; 1014 return collector_policy()->mem_allocate_work(size /* size */, 1015 true /* is_tlab */, 1016 &gc_overhead_limit_was_exceeded); 1017 } 1018 1019 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1020 // from the list headed by "*prev_ptr". 1021 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1022 bool first = true; 1023 size_t min_size = 0; // "first" makes this conceptually infinite. 1024 ScratchBlock **smallest_ptr, *smallest; 1025 ScratchBlock *cur = *prev_ptr; 1026 while (cur) { 1027 assert(*prev_ptr == cur, "just checking"); 1028 if (first || cur->num_words < min_size) { 1029 smallest_ptr = prev_ptr; 1030 smallest = cur; 1031 min_size = smallest->num_words; 1032 first = false; 1033 } 1034 prev_ptr = &cur->next; 1035 cur = cur->next; 1036 } 1037 smallest = *smallest_ptr; 1038 *smallest_ptr = smallest->next; 1039 return smallest; 1040 } 1041 1042 // Sort the scratch block list headed by res into decreasing size order, 1043 // and set "res" to the result. 1044 static void sort_scratch_list(ScratchBlock*& list) { 1045 ScratchBlock* sorted = NULL; 1046 ScratchBlock* unsorted = list; 1047 while (unsorted) { 1048 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1049 smallest->next = sorted; 1050 sorted = smallest; 1051 } 1052 list = sorted; 1053 } 1054 1055 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1056 size_t max_alloc_words) { 1057 ScratchBlock* res = NULL; 1058 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1059 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1060 sort_scratch_list(res); 1061 return res; 1062 } 1063 1064 void GenCollectedHeap::release_scratch() { 1065 _young_gen->reset_scratch(); 1066 _old_gen->reset_scratch(); 1067 } 1068 1069 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1070 void do_generation(Generation* gen) { 1071 gen->prepare_for_verify(); 1072 } 1073 }; 1074 1075 void GenCollectedHeap::prepare_for_verify() { 1076 ensure_parsability(false); // no need to retire TLABs 1077 GenPrepareForVerifyClosure blk; 1078 generation_iterate(&blk, false); 1079 } 1080 1081 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1082 bool old_to_young) { 1083 if (old_to_young) { 1084 cl->do_generation(_old_gen); 1085 cl->do_generation(_young_gen); 1086 } else { 1087 cl->do_generation(_young_gen); 1088 cl->do_generation(_old_gen); 1089 } 1090 } 1091 1092 bool GenCollectedHeap::is_maximal_no_gc() const { 1093 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1094 } 1095 1096 void GenCollectedHeap::save_marks() { 1097 _young_gen->save_marks(); 1098 _old_gen->save_marks(); 1099 } 1100 1101 GenCollectedHeap* GenCollectedHeap::heap() { 1102 CollectedHeap* heap = Universe::heap(); 1103 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1104 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap"); 1105 return (GenCollectedHeap*)heap; 1106 } 1107 1108 void GenCollectedHeap::prepare_for_compaction() { 1109 // Start by compacting into same gen. 1110 CompactPoint cp(_old_gen); 1111 _old_gen->prepare_for_compaction(&cp); 1112 _young_gen->prepare_for_compaction(&cp); 1113 } 1114 1115 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) { 1116 if (!silent) { 1117 gclog_or_tty->print("%s", _old_gen->name()); 1118 gclog_or_tty->print(" "); 1119 } 1120 _old_gen->verify(); 1121 1122 if (!silent) { 1123 gclog_or_tty->print("%s", _young_gen->name()); 1124 gclog_or_tty->print(" "); 1125 } 1126 _young_gen->verify(); 1127 1128 if (!silent) { 1129 gclog_or_tty->print("remset "); 1130 } 1131 rem_set()->verify(); 1132 } 1133 1134 void GenCollectedHeap::print_on(outputStream* st) const { 1135 _young_gen->print_on(st); 1136 _old_gen->print_on(st); 1137 MetaspaceAux::print_on(st); 1138 } 1139 1140 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1141 if (workers() != NULL) { 1142 workers()->threads_do(tc); 1143 } 1144 #if INCLUDE_ALL_GCS 1145 if (UseConcMarkSweepGC) { 1146 ConcurrentMarkSweepThread::threads_do(tc); 1147 } 1148 #endif // INCLUDE_ALL_GCS 1149 } 1150 1151 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1152 #if INCLUDE_ALL_GCS 1153 if (UseConcMarkSweepGC) { 1154 workers()->print_worker_threads_on(st); 1155 ConcurrentMarkSweepThread::print_all_on(st); 1156 } 1157 #endif // INCLUDE_ALL_GCS 1158 } 1159 1160 void GenCollectedHeap::print_on_error(outputStream* st) const { 1161 this->CollectedHeap::print_on_error(st); 1162 1163 #if INCLUDE_ALL_GCS 1164 if (UseConcMarkSweepGC) { 1165 st->cr(); 1166 CMSCollector::print_on_error(st); 1167 } 1168 #endif // INCLUDE_ALL_GCS 1169 } 1170 1171 void GenCollectedHeap::print_tracing_info() const { 1172 if (TraceYoungGenTime) { 1173 _young_gen->print_summary_info(); 1174 } 1175 if (TraceOldGenTime) { 1176 _old_gen->print_summary_info(); 1177 } 1178 } 1179 1180 void GenCollectedHeap::print_heap_change(size_t prev_used) const { 1181 if (PrintGCDetails && Verbose) { 1182 gclog_or_tty->print(" " SIZE_FORMAT 1183 "->" SIZE_FORMAT 1184 "(" SIZE_FORMAT ")", 1185 prev_used, used(), capacity()); 1186 } else { 1187 gclog_or_tty->print(" " SIZE_FORMAT "K" 1188 "->" SIZE_FORMAT "K" 1189 "(" SIZE_FORMAT "K)", 1190 prev_used / K, used() / K, capacity() / K); 1191 } 1192 } 1193 1194 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1195 private: 1196 bool _full; 1197 public: 1198 void do_generation(Generation* gen) { 1199 gen->gc_prologue(_full); 1200 } 1201 GenGCPrologueClosure(bool full) : _full(full) {}; 1202 }; 1203 1204 void GenCollectedHeap::gc_prologue(bool full) { 1205 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1206 1207 always_do_update_barrier = false; 1208 // Fill TLAB's and such 1209 CollectedHeap::accumulate_statistics_all_tlabs(); 1210 ensure_parsability(true); // retire TLABs 1211 1212 // Walk generations 1213 GenGCPrologueClosure blk(full); 1214 generation_iterate(&blk, false); // not old-to-young. 1215 }; 1216 1217 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1218 private: 1219 bool _full; 1220 public: 1221 void do_generation(Generation* gen) { 1222 gen->gc_epilogue(_full); 1223 } 1224 GenGCEpilogueClosure(bool full) : _full(full) {}; 1225 }; 1226 1227 void GenCollectedHeap::gc_epilogue(bool full) { 1228 #ifdef COMPILER2 1229 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1230 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1231 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1232 #endif /* COMPILER2 */ 1233 1234 resize_all_tlabs(); 1235 1236 GenGCEpilogueClosure blk(full); 1237 generation_iterate(&blk, false); // not old-to-young. 1238 1239 if (!CleanChunkPoolAsync) { 1240 Chunk::clean_chunk_pool(); 1241 } 1242 1243 MetaspaceCounters::update_performance_counters(); 1244 CompressedClassSpaceCounters::update_performance_counters(); 1245 1246 always_do_update_barrier = UseConcMarkSweepGC; 1247 }; 1248 1249 #ifndef PRODUCT 1250 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1251 private: 1252 public: 1253 void do_generation(Generation* gen) { 1254 gen->record_spaces_top(); 1255 } 1256 }; 1257 1258 void GenCollectedHeap::record_gen_tops_before_GC() { 1259 if (ZapUnusedHeapArea) { 1260 GenGCSaveTopsBeforeGCClosure blk; 1261 generation_iterate(&blk, false); // not old-to-young. 1262 } 1263 } 1264 #endif // not PRODUCT 1265 1266 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1267 public: 1268 void do_generation(Generation* gen) { 1269 gen->ensure_parsability(); 1270 } 1271 }; 1272 1273 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1274 CollectedHeap::ensure_parsability(retire_tlabs); 1275 GenEnsureParsabilityClosure ep_cl; 1276 generation_iterate(&ep_cl, false); 1277 } 1278 1279 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1280 oop obj, 1281 size_t obj_size) { 1282 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1283 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1284 HeapWord* result = NULL; 1285 1286 result = old_gen->expand_and_allocate(obj_size, false); 1287 1288 if (result != NULL) { 1289 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1290 } 1291 return oop(result); 1292 } 1293 1294 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1295 jlong _time; // in ms 1296 jlong _now; // in ms 1297 1298 public: 1299 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1300 1301 jlong time() { return _time; } 1302 1303 void do_generation(Generation* gen) { 1304 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1305 } 1306 }; 1307 1308 jlong GenCollectedHeap::millis_since_last_gc() { 1309 // We need a monotonically non-decreasing time in ms but 1310 // os::javaTimeMillis() does not guarantee monotonicity. 1311 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1312 GenTimeOfLastGCClosure tolgc_cl(now); 1313 // iterate over generations getting the oldest 1314 // time that a generation was collected 1315 generation_iterate(&tolgc_cl, false); 1316 1317 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1318 // provided the underlying platform provides such a time source 1319 // (and it is bug free). So we still have to guard against getting 1320 // back a time later than 'now'. 1321 jlong retVal = now - tolgc_cl.time(); 1322 if (retVal < 0) { 1323 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);) 1324 return 0; 1325 } 1326 return retVal; 1327 }