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_implementation/shared/collectorCounters.hpp" 32 #include "gc_implementation/shared/gcTrace.hpp" 33 #include "gc_implementation/shared/gcTraceTime.hpp" 34 #include "gc_implementation/shared/vmGCOperations.hpp" 35 #include "gc_interface/collectedHeap.inline.hpp" 36 #include "memory/filemap.hpp" 37 #include "memory/gcLocker.inline.hpp" 38 #include "memory/genCollectedHeap.hpp" 39 #include "memory/genOopClosures.inline.hpp" 40 #include "memory/generationSpec.hpp" 41 #include "memory/resourceArea.hpp" 42 #include "memory/sharedHeap.hpp" 43 #include "memory/space.hpp" 44 #include "oops/oop.inline.hpp" 45 #include "runtime/biasedLocking.hpp" 46 #include "runtime/fprofiler.hpp" 47 #include "runtime/handles.hpp" 48 #include "runtime/handles.inline.hpp" 49 #include "runtime/java.hpp" 50 #include "runtime/vmThread.hpp" 51 #include "services/management.hpp" 52 #include "services/memoryService.hpp" 53 #include "utilities/vmError.hpp" 54 #include "utilities/workgroup.hpp" 55 #include "utilities/macros.hpp" 56 #if INCLUDE_ALL_GCS 57 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp" 58 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp" 59 #endif // INCLUDE_ALL_GCS 60 61 GenCollectedHeap* GenCollectedHeap::_gch; 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 SharedHeap(), 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 } 89 90 jint GenCollectedHeap::initialize() { 91 CollectedHeap::pre_initialize(); 92 93 _n_gens = gen_policy()->number_of_generations(); 94 assert(_n_gens == 2, "There is no support for more than two generations"); 95 96 // While there are no constraints in the GC code that HeapWordSize 97 // be any particular value, there are multiple other areas in the 98 // system which believe this to be true (e.g. oop->object_size in some 99 // cases incorrectly returns the size in wordSize units rather than 100 // HeapWordSize). 101 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 102 103 // Allocate space for the heap. 104 105 char* heap_address; 106 ReservedSpace heap_rs; 107 108 size_t heap_alignment = collector_policy()->heap_alignment(); 109 110 heap_address = allocate(heap_alignment, &heap_rs); 111 112 if (!heap_rs.is_reserved()) { 113 vm_shutdown_during_initialization( 114 "Could not reserve enough space for object heap"); 115 return JNI_ENOMEM; 116 } 117 118 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 119 120 _rem_set = collector_policy()->create_rem_set(reserved_region()); 121 _barrier_set = rem_set()->bs(); 122 oopDesc::set_bs(_barrier_set); 123 124 _gch = this; 125 126 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false); 127 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set()); 128 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size()); 129 130 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false); 131 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set()); 132 clear_incremental_collection_failed(); 133 134 #if INCLUDE_ALL_GCS 135 // If we are running CMS, create the collector responsible 136 // for collecting the CMS generations. 137 if (collector_policy()->is_concurrent_mark_sweep_policy()) { 138 bool success = create_cms_collector(); 139 if (!success) return JNI_ENOMEM; 140 } 141 #endif // INCLUDE_ALL_GCS 142 143 return JNI_OK; 144 } 145 146 char* GenCollectedHeap::allocate(size_t alignment, 147 ReservedSpace* heap_rs){ 148 // Now figure out the total size. 149 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 150 assert(alignment % pageSize == 0, "Must be"); 151 152 GenerationSpec* young_spec = gen_policy()->young_gen_spec(); 153 GenerationSpec* old_spec = gen_policy()->old_gen_spec(); 154 155 // Check for overflow. 156 size_t total_reserved = young_spec->max_size() + old_spec->max_size(); 157 if (total_reserved < young_spec->max_size()) { 158 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 159 "the maximum representable size"); 160 } 161 assert(total_reserved % alignment == 0, 162 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 163 SIZE_FORMAT, total_reserved, alignment)); 164 165 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 166 return heap_rs->base(); 167 } 168 169 void GenCollectedHeap::post_initialize() { 170 CollectedHeap::post_initialize(); 171 ref_processing_init(); 172 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy(); 173 guarantee(policy->is_generation_policy(), "Illegal policy type"); 174 assert((_young_gen->kind() == Generation::DefNew) || 175 (_young_gen->kind() == Generation::ParNew), 176 "Wrong youngest generation type"); 177 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 178 179 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep || 180 _old_gen->kind() == Generation::MarkSweepCompact, 181 "Wrong generation kind"); 182 183 policy->initialize_size_policy(def_new_gen->eden()->capacity(), 184 _old_gen->capacity(), 185 def_new_gen->from()->capacity()); 186 policy->initialize_gc_policy_counters(); 187 } 188 189 void GenCollectedHeap::ref_processing_init() { 190 _young_gen->ref_processor_init(); 191 _old_gen->ref_processor_init(); 192 } 193 194 size_t GenCollectedHeap::capacity() const { 195 return _young_gen->capacity() + _old_gen->capacity(); 196 } 197 198 size_t GenCollectedHeap::used() const { 199 return _young_gen->used() + _old_gen->used(); 200 } 201 202 // Save the "used_region" for generations level and lower. 203 void GenCollectedHeap::save_used_regions(int level) { 204 assert(level >= 0, "Illegal level parameter"); 205 assert(level < _n_gens, "Illegal level parameter"); 206 if (level == 1) { 207 _old_gen->save_used_region(); 208 } 209 _young_gen->save_used_region(); 210 } 211 212 size_t GenCollectedHeap::max_capacity() const { 213 return _young_gen->max_capacity() + _old_gen->max_capacity(); 214 } 215 216 // Update the _full_collections_completed counter 217 // at the end of a stop-world full GC. 218 unsigned int GenCollectedHeap::update_full_collections_completed() { 219 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 220 assert(_full_collections_completed <= _total_full_collections, 221 "Can't complete more collections than were started"); 222 _full_collections_completed = _total_full_collections; 223 ml.notify_all(); 224 return _full_collections_completed; 225 } 226 227 // Update the _full_collections_completed counter, as appropriate, 228 // at the end of a concurrent GC cycle. Note the conditional update 229 // below to allow this method to be called by a concurrent collector 230 // without synchronizing in any manner with the VM thread (which 231 // may already have initiated a STW full collection "concurrently"). 232 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 233 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 234 assert((_full_collections_completed <= _total_full_collections) && 235 (count <= _total_full_collections), 236 "Can't complete more collections than were started"); 237 if (count > _full_collections_completed) { 238 _full_collections_completed = count; 239 ml.notify_all(); 240 } 241 return _full_collections_completed; 242 } 243 244 245 #ifndef PRODUCT 246 // Override of memory state checking method in CollectedHeap: 247 // Some collectors (CMS for example) can't have badHeapWordVal written 248 // in the first two words of an object. (For instance , in the case of 249 // CMS these words hold state used to synchronize between certain 250 // (concurrent) GC steps and direct allocating mutators.) 251 // The skip_header_HeapWords() method below, allows us to skip 252 // over the requisite number of HeapWord's. Note that (for 253 // generational collectors) this means that those many words are 254 // skipped in each object, irrespective of the generation in which 255 // that object lives. The resultant loss of precision seems to be 256 // harmless and the pain of avoiding that imprecision appears somewhat 257 // higher than we are prepared to pay for such rudimentary debugging 258 // support. 259 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 260 size_t size) { 261 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 262 // We are asked to check a size in HeapWords, 263 // but the memory is mangled in juint words. 264 juint* start = (juint*) (addr + skip_header_HeapWords()); 265 juint* end = (juint*) (addr + size); 266 for (juint* slot = start; slot < end; slot += 1) { 267 assert(*slot == badHeapWordVal, 268 "Found non badHeapWordValue in pre-allocation check"); 269 } 270 } 271 } 272 #endif 273 274 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 275 bool is_tlab, 276 bool first_only) { 277 HeapWord* res = NULL; 278 279 if (_young_gen->should_allocate(size, is_tlab)) { 280 res = _young_gen->allocate(size, is_tlab); 281 if (res != NULL || first_only) { 282 return res; 283 } 284 } 285 286 if (_old_gen->should_allocate(size, is_tlab)) { 287 res = _old_gen->allocate(size, is_tlab); 288 } 289 290 return res; 291 } 292 293 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 294 bool* gc_overhead_limit_was_exceeded) { 295 return collector_policy()->mem_allocate_work(size, 296 false /* is_tlab */, 297 gc_overhead_limit_was_exceeded); 298 } 299 300 bool GenCollectedHeap::must_clear_all_soft_refs() { 301 return _gc_cause == GCCause::_last_ditch_collection; 302 } 303 304 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 305 return UseConcMarkSweepGC && 306 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) || 307 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)); 308 } 309 310 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 311 bool is_tlab, bool run_verification, bool clear_soft_refs, 312 bool restore_marks_for_biased_locking) { 313 // Timer for individual generations. Last argument is false: no CR 314 // FIXME: We should try to start the timing earlier to cover more of the GC pause 315 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 316 // so we can assume here that the next GC id is what we want. 317 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek()); 318 TraceCollectorStats tcs(gen->counters()); 319 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 320 321 size_t prev_used = gen->used(); 322 gen->stat_record()->invocations++; 323 gen->stat_record()->accumulated_time.start(); 324 325 // Must be done anew before each collection because 326 // a previous collection will do mangling and will 327 // change top of some spaces. 328 record_gen_tops_before_GC(); 329 330 if (PrintGC && Verbose) { 331 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT, 332 gen->level(), 333 gen->stat_record()->invocations, 334 size * HeapWordSize); 335 } 336 337 if (run_verification && VerifyBeforeGC) { 338 HandleMark hm; // Discard invalid handles created during verification 339 Universe::verify(" VerifyBeforeGC:"); 340 } 341 COMPILER2_PRESENT(DerivedPointerTable::clear()); 342 343 if (restore_marks_for_biased_locking) { 344 // We perform this mark word preservation work lazily 345 // because it's only at this point that we know whether we 346 // absolutely have to do it; we want to avoid doing it for 347 // scavenge-only collections where it's unnecessary 348 BiasedLocking::preserve_marks(); 349 } 350 351 // Do collection work 352 { 353 // Note on ref discovery: For what appear to be historical reasons, 354 // GCH enables and disabled (by enqueing) refs discovery. 355 // In the future this should be moved into the generation's 356 // collect method so that ref discovery and enqueueing concerns 357 // are local to a generation. The collect method could return 358 // an appropriate indication in the case that notification on 359 // the ref lock was needed. This will make the treatment of 360 // weak refs more uniform (and indeed remove such concerns 361 // from GCH). XXX 362 363 HandleMark hm; // Discard invalid handles created during gc 364 save_marks(); // save marks for all gens 365 // We want to discover references, but not process them yet. 366 // This mode is disabled in process_discovered_references if the 367 // generation does some collection work, or in 368 // enqueue_discovered_references if the generation returns 369 // without doing any work. 370 ReferenceProcessor* rp = gen->ref_processor(); 371 // If the discovery of ("weak") refs in this generation is 372 // atomic wrt other collectors in this configuration, we 373 // are guaranteed to have empty discovered ref lists. 374 if (rp->discovery_is_atomic()) { 375 rp->enable_discovery(); 376 rp->setup_policy(clear_soft_refs); 377 } else { 378 // collect() below will enable discovery as appropriate 379 } 380 gen->collect(full, clear_soft_refs, size, is_tlab); 381 if (!rp->enqueuing_is_done()) { 382 rp->enqueue_discovered_references(); 383 } else { 384 rp->set_enqueuing_is_done(false); 385 } 386 rp->verify_no_references_recorded(); 387 } 388 389 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 390 391 gen->stat_record()->accumulated_time.stop(); 392 393 update_gc_stats(gen->level(), full); 394 395 if (run_verification && VerifyAfterGC) { 396 HandleMark hm; // Discard invalid handles created during verification 397 Universe::verify(" VerifyAfterGC:"); 398 } 399 400 if (PrintGCDetails) { 401 gclog_or_tty->print(":"); 402 gen->print_heap_change(prev_used); 403 } 404 } 405 406 void GenCollectedHeap::do_collection(bool full, 407 bool clear_all_soft_refs, 408 size_t size, 409 bool is_tlab, 410 int max_level) { 411 ResourceMark rm; 412 DEBUG_ONLY(Thread* my_thread = Thread::current();) 413 414 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 415 assert(my_thread->is_VM_thread() || 416 my_thread->is_ConcurrentGC_thread(), 417 "incorrect thread type capability"); 418 assert(Heap_lock->is_locked(), 419 "the requesting thread should have the Heap_lock"); 420 guarantee(!is_gc_active(), "collection is not reentrant"); 421 assert(max_level < n_gens(), "sanity check"); 422 423 if (GC_locker::check_active_before_gc()) { 424 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 425 } 426 427 const bool do_clear_all_soft_refs = clear_all_soft_refs || 428 collector_policy()->should_clear_all_soft_refs(); 429 430 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 431 432 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 433 434 print_heap_before_gc(); 435 436 { 437 FlagSetting fl(_is_gc_active, true); 438 439 bool complete = full && (max_level == (n_gens()-1)); 440 const char* gc_cause_prefix = complete ? "Full GC" : "GC"; 441 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 442 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 443 // so we can assume here that the next GC id is what we want. 444 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek()); 445 446 gc_prologue(complete); 447 increment_total_collections(complete); 448 449 size_t gch_prev_used = used(); 450 bool run_verification = total_collections() >= VerifyGCStartAt; 451 452 bool prepared_for_verification = false; 453 int max_level_collected = 0; 454 bool old_collects_young = (max_level == 1) && 455 full && 456 _old_gen->full_collects_younger_generations(); 457 if (!old_collects_young && 458 _young_gen->should_collect(full, size, is_tlab)) { 459 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 460 prepare_for_verify(); 461 prepared_for_verification = true; 462 } 463 464 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking"); 465 collect_generation(_young_gen, 466 full, 467 size, 468 is_tlab, 469 run_verification && VerifyGCLevel <= 0, 470 do_clear_all_soft_refs, 471 false); 472 473 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 474 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 475 // Allocation request was met by young GC. 476 size = 0; 477 } 478 } 479 480 bool must_restore_marks_for_biased_locking = false; 481 482 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) { 483 if (!complete) { 484 // The full_collections increment was missed above. 485 increment_total_full_collections(); 486 } 487 488 pre_full_gc_dump(NULL); // do any pre full gc dumps 489 490 if (!prepared_for_verification && run_verification && 491 VerifyGCLevel <= 1 && VerifyBeforeGC) { 492 prepare_for_verify(); 493 } 494 495 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking"); 496 collect_generation(_old_gen, 497 full, 498 size, 499 is_tlab, 500 run_verification && VerifyGCLevel <= 1, 501 do_clear_all_soft_refs, 502 true); 503 504 must_restore_marks_for_biased_locking = true; 505 max_level_collected = 1; 506 } 507 508 // Update "complete" boolean wrt what actually transpired -- 509 // for instance, a promotion failure could have led to 510 // a whole heap collection. 511 complete = complete || (max_level_collected == n_gens() - 1); 512 513 if (complete) { // We did a "major" collection 514 // FIXME: See comment at pre_full_gc_dump call 515 post_full_gc_dump(NULL); // do any post full gc dumps 516 } 517 518 if (PrintGCDetails) { 519 print_heap_change(gch_prev_used); 520 521 // Print metaspace info for full GC with PrintGCDetails flag. 522 if (complete) { 523 MetaspaceAux::print_metaspace_change(metadata_prev_used); 524 } 525 } 526 527 // Adjust generation sizes. 528 if (max_level_collected == 1) { 529 _old_gen->compute_new_size(); 530 } 531 _young_gen->compute_new_size(); 532 533 if (complete) { 534 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 535 ClassLoaderDataGraph::purge(); 536 MetaspaceAux::verify_metrics(); 537 // Resize the metaspace capacity after full collections 538 MetaspaceGC::compute_new_size(); 539 update_full_collections_completed(); 540 } 541 542 // Track memory usage and detect low memory after GC finishes 543 MemoryService::track_memory_usage(); 544 545 gc_epilogue(complete); 546 547 if (must_restore_marks_for_biased_locking) { 548 BiasedLocking::restore_marks(); 549 } 550 } 551 552 print_heap_after_gc(); 553 554 #ifdef TRACESPINNING 555 ParallelTaskTerminator::print_termination_counts(); 556 #endif 557 } 558 559 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 560 return collector_policy()->satisfy_failed_allocation(size, is_tlab); 561 } 562 563 void GenCollectedHeap::set_par_threads(uint t) { 564 SharedHeap::set_par_threads(t); 565 set_n_termination(t); 566 } 567 568 void GenCollectedHeap::set_n_termination(uint t) { 569 _process_strong_tasks->set_n_threads(t); 570 } 571 572 #ifdef ASSERT 573 class AssertNonScavengableClosure: public OopClosure { 574 public: 575 virtual void do_oop(oop* p) { 576 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 577 "Referent should not be scavengable."); } 578 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 579 }; 580 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 581 #endif 582 583 void GenCollectedHeap::process_roots(bool activate_scope, 584 ScanningOption so, 585 OopClosure* strong_roots, 586 OopClosure* weak_roots, 587 CLDClosure* strong_cld_closure, 588 CLDClosure* weak_cld_closure, 589 CodeBlobClosure* code_roots) { 590 StrongRootsScope srs(this, activate_scope); 591 592 // General roots. 593 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 594 assert(code_roots != NULL, "code root closure should always be set"); 595 // _n_termination for _process_strong_tasks should be set up stream 596 // in a method not running in a GC worker. Otherwise the GC worker 597 // could be trying to change the termination condition while the task 598 // is executing in another GC worker. 599 600 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 601 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 602 } 603 604 // Some CLDs contained in the thread frames should be considered strong. 605 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 606 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 607 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 608 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 609 610 bool is_par =n_par_threads() > 0; 611 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p); 612 613 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 614 Universe::oops_do(strong_roots); 615 } 616 // Global (strong) JNI handles 617 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 618 JNIHandles::oops_do(strong_roots); 619 } 620 621 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 622 ObjectSynchronizer::oops_do(strong_roots); 623 } 624 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 625 FlatProfiler::oops_do(strong_roots); 626 } 627 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 628 Management::oops_do(strong_roots); 629 } 630 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 631 JvmtiExport::oops_do(strong_roots); 632 } 633 634 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 635 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 636 } 637 638 // All threads execute the following. A specific chunk of buckets 639 // from the StringTable are the individual tasks. 640 if (weak_roots != NULL) { 641 if (CollectedHeap::use_parallel_gc_threads()) { 642 StringTable::possibly_parallel_oops_do(weak_roots); 643 } else { 644 StringTable::oops_do(weak_roots); 645 } 646 } 647 648 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 649 if (so & SO_ScavengeCodeCache) { 650 assert(code_roots != NULL, "must supply closure for code cache"); 651 652 // We only visit parts of the CodeCache when scavenging. 653 CodeCache::scavenge_root_nmethods_do(code_roots); 654 } 655 if (so & SO_AllCodeCache) { 656 assert(code_roots != NULL, "must supply closure for code cache"); 657 658 // CMSCollector uses this to do intermediate-strength collections. 659 // We scan the entire code cache, since CodeCache::do_unloading is not called. 660 CodeCache::blobs_do(code_roots); 661 } 662 // Verify that the code cache contents are not subject to 663 // movement by a scavenging collection. 664 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 665 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 666 } 667 668 } 669 670 void GenCollectedHeap::gen_process_roots(int level, 671 bool younger_gens_as_roots, 672 bool activate_scope, 673 ScanningOption so, 674 bool only_strong_roots, 675 OopsInGenClosure* not_older_gens, 676 OopsInGenClosure* older_gens, 677 CLDClosure* cld_closure) { 678 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots; 679 680 bool is_moving_collection = false; 681 if (level == 0 || is_adjust_phase) { 682 // young collections are always moving 683 is_moving_collection = true; 684 } 685 686 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection); 687 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens; 688 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 689 690 process_roots(activate_scope, so, 691 not_older_gens, weak_roots, 692 cld_closure, weak_cld_closure, 693 &mark_code_closure); 694 695 if (younger_gens_as_roots) { 696 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 697 if (level == 1) { 698 not_older_gens->set_generation(_young_gen); 699 _young_gen->oop_iterate(not_older_gens); 700 } 701 not_older_gens->reset_generation(); 702 } 703 } 704 // When collection is parallel, all threads get to cooperate to do 705 // older-gen scanning. 706 if (level == 0) { 707 older_gens->set_generation(_old_gen); 708 rem_set()->younger_refs_iterate(_old_gen, older_gens); 709 older_gens->reset_generation(); 710 } 711 712 _process_strong_tasks->all_tasks_completed(); 713 } 714 715 716 class AlwaysTrueClosure: public BoolObjectClosure { 717 public: 718 bool do_object_b(oop p) { return true; } 719 }; 720 static AlwaysTrueClosure always_true; 721 722 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 723 JNIHandles::weak_oops_do(&always_true, root_closure); 724 _young_gen->ref_processor()->weak_oops_do(root_closure); 725 _old_gen->ref_processor()->weak_oops_do(root_closure); 726 } 727 728 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 729 void GenCollectedHeap:: \ 730 oop_since_save_marks_iterate(int level, \ 731 OopClosureType* cur, \ 732 OopClosureType* older) { \ 733 if (level == 0) { \ 734 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 735 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 736 } else { \ 737 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 738 } \ 739 } 740 741 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 742 743 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 744 745 bool GenCollectedHeap::no_allocs_since_save_marks(int level) { 746 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) { 747 return false; 748 } 749 return _old_gen->no_allocs_since_save_marks(); 750 } 751 752 bool GenCollectedHeap::supports_inline_contig_alloc() const { 753 return _young_gen->supports_inline_contig_alloc(); 754 } 755 756 HeapWord** GenCollectedHeap::top_addr() const { 757 return _young_gen->top_addr(); 758 } 759 760 HeapWord** GenCollectedHeap::end_addr() const { 761 return _young_gen->end_addr(); 762 } 763 764 // public collection interfaces 765 766 void GenCollectedHeap::collect(GCCause::Cause cause) { 767 if (should_do_concurrent_full_gc(cause)) { 768 #if INCLUDE_ALL_GCS 769 // mostly concurrent full collection 770 collect_mostly_concurrent(cause); 771 #else // INCLUDE_ALL_GCS 772 ShouldNotReachHere(); 773 #endif // INCLUDE_ALL_GCS 774 } else if (cause == GCCause::_wb_young_gc) { 775 // minor collection for WhiteBox API 776 collect(cause, 0); 777 } else { 778 #ifdef ASSERT 779 if (cause == GCCause::_scavenge_alot) { 780 // minor collection only 781 collect(cause, 0); 782 } else { 783 // Stop-the-world full collection 784 collect(cause, n_gens() - 1); 785 } 786 #else 787 // Stop-the-world full collection 788 collect(cause, n_gens() - 1); 789 #endif 790 } 791 } 792 793 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) { 794 // The caller doesn't have the Heap_lock 795 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 796 MutexLocker ml(Heap_lock); 797 collect_locked(cause, max_level); 798 } 799 800 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 801 // The caller has the Heap_lock 802 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 803 collect_locked(cause, n_gens() - 1); 804 } 805 806 // this is the private collection interface 807 // The Heap_lock is expected to be held on entry. 808 809 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) { 810 // Read the GC count while holding the Heap_lock 811 unsigned int gc_count_before = total_collections(); 812 unsigned int full_gc_count_before = total_full_collections(); 813 { 814 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 815 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 816 cause, max_level); 817 VMThread::execute(&op); 818 } 819 } 820 821 #if INCLUDE_ALL_GCS 822 bool GenCollectedHeap::create_cms_collector() { 823 824 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 825 "Unexpected generation kinds"); 826 // Skip two header words in the block content verification 827 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 828 CMSCollector* collector = new CMSCollector( 829 (ConcurrentMarkSweepGeneration*)_old_gen, 830 _rem_set->as_CardTableRS(), 831 (ConcurrentMarkSweepPolicy*) collector_policy()); 832 833 if (collector == NULL || !collector->completed_initialization()) { 834 if (collector) { 835 delete collector; // Be nice in embedded situation 836 } 837 vm_shutdown_during_initialization("Could not create CMS collector"); 838 return false; 839 } 840 return true; // success 841 } 842 843 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 844 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 845 846 MutexLocker ml(Heap_lock); 847 // Read the GC counts while holding the Heap_lock 848 unsigned int full_gc_count_before = total_full_collections(); 849 unsigned int gc_count_before = total_collections(); 850 { 851 MutexUnlocker mu(Heap_lock); 852 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 853 VMThread::execute(&op); 854 } 855 } 856 #endif // INCLUDE_ALL_GCS 857 858 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 859 do_full_collection(clear_all_soft_refs, _n_gens - 1); 860 } 861 862 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 863 int max_level) { 864 int local_max_level; 865 if (!incremental_collection_will_fail(false /* don't consult_young */) && 866 gc_cause() == GCCause::_gc_locker) { 867 local_max_level = 0; 868 } else { 869 local_max_level = max_level; 870 } 871 872 do_collection(true /* full */, 873 clear_all_soft_refs /* clear_all_soft_refs */, 874 0 /* size */, 875 false /* is_tlab */, 876 local_max_level /* max_level */); 877 // Hack XXX FIX ME !!! 878 // A scavenge may not have been attempted, or may have 879 // been attempted and failed, because the old gen was too full 880 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker && 881 incremental_collection_will_fail(false /* don't consult_young */)) { 882 if (PrintGCDetails) { 883 gclog_or_tty->print_cr("GC locker: Trying a full collection " 884 "because scavenge failed"); 885 } 886 // This time allow the old gen to be collected as well 887 do_collection(true /* full */, 888 clear_all_soft_refs /* clear_all_soft_refs */, 889 0 /* size */, 890 false /* is_tlab */, 891 n_gens() - 1 /* max_level */); 892 } 893 } 894 895 bool GenCollectedHeap::is_in_young(oop p) { 896 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 897 assert(result == _young_gen->is_in_reserved(p), 898 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p))); 899 return result; 900 } 901 902 // Returns "TRUE" iff "p" points into the committed areas of the heap. 903 bool GenCollectedHeap::is_in(const void* p) const { 904 #ifndef ASSERT 905 guarantee(VerifyBeforeGC || 906 VerifyDuringGC || 907 VerifyBeforeExit || 908 VerifyDuringStartup || 909 PrintAssembly || 910 tty->count() != 0 || // already printing 911 VerifyAfterGC || 912 VMError::fatal_error_in_progress(), "too expensive"); 913 914 #endif 915 return _young_gen->is_in(p) || _old_gen->is_in(p); 916 } 917 918 #ifdef ASSERT 919 // Don't implement this by using is_in_young(). This method is used 920 // in some cases to check that is_in_young() is correct. 921 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 922 assert(is_in_reserved(p) || p == NULL, 923 "Does not work if address is non-null and outside of the heap"); 924 return p < _young_gen->reserved().end() && p != NULL; 925 } 926 #endif 927 928 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 929 _young_gen->oop_iterate(cl); 930 _old_gen->oop_iterate(cl); 931 } 932 933 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 934 _young_gen->object_iterate(cl); 935 _old_gen->object_iterate(cl); 936 } 937 938 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 939 _young_gen->safe_object_iterate(cl); 940 _old_gen->safe_object_iterate(cl); 941 } 942 943 Space* GenCollectedHeap::space_containing(const void* addr) const { 944 Space* res = _young_gen->space_containing(addr); 945 if (res != NULL) { 946 return res; 947 } 948 res = _old_gen->space_containing(addr); 949 assert(res != NULL, "Could not find containing space"); 950 return res; 951 } 952 953 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 954 assert(is_in_reserved(addr), "block_start of address outside of heap"); 955 if (_young_gen->is_in_reserved(addr)) { 956 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 957 return _young_gen->block_start(addr); 958 } 959 960 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 961 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 962 return _old_gen->block_start(addr); 963 } 964 965 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 966 assert(is_in_reserved(addr), "block_size of address outside of heap"); 967 if (_young_gen->is_in_reserved(addr)) { 968 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 969 return _young_gen->block_size(addr); 970 } 971 972 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 973 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 974 return _old_gen->block_size(addr); 975 } 976 977 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 978 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 979 assert(block_start(addr) == addr, "addr must be a block start"); 980 if (_young_gen->is_in_reserved(addr)) { 981 return _young_gen->block_is_obj(addr); 982 } 983 984 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 985 return _old_gen->block_is_obj(addr); 986 } 987 988 bool GenCollectedHeap::supports_tlab_allocation() const { 989 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 990 return _young_gen->supports_tlab_allocation(); 991 } 992 993 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 994 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 995 if (_young_gen->supports_tlab_allocation()) { 996 return _young_gen->tlab_capacity(); 997 } 998 return 0; 999 } 1000 1001 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 1002 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1003 if (_young_gen->supports_tlab_allocation()) { 1004 return _young_gen->tlab_used(); 1005 } 1006 return 0; 1007 } 1008 1009 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 1010 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1011 if (_young_gen->supports_tlab_allocation()) { 1012 return _young_gen->unsafe_max_tlab_alloc(); 1013 } 1014 return 0; 1015 } 1016 1017 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 1018 bool gc_overhead_limit_was_exceeded; 1019 return collector_policy()->mem_allocate_work(size /* size */, 1020 true /* is_tlab */, 1021 &gc_overhead_limit_was_exceeded); 1022 } 1023 1024 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1025 // from the list headed by "*prev_ptr". 1026 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1027 bool first = true; 1028 size_t min_size = 0; // "first" makes this conceptually infinite. 1029 ScratchBlock **smallest_ptr, *smallest; 1030 ScratchBlock *cur = *prev_ptr; 1031 while (cur) { 1032 assert(*prev_ptr == cur, "just checking"); 1033 if (first || cur->num_words < min_size) { 1034 smallest_ptr = prev_ptr; 1035 smallest = cur; 1036 min_size = smallest->num_words; 1037 first = false; 1038 } 1039 prev_ptr = &cur->next; 1040 cur = cur->next; 1041 } 1042 smallest = *smallest_ptr; 1043 *smallest_ptr = smallest->next; 1044 return smallest; 1045 } 1046 1047 // Sort the scratch block list headed by res into decreasing size order, 1048 // and set "res" to the result. 1049 static void sort_scratch_list(ScratchBlock*& list) { 1050 ScratchBlock* sorted = NULL; 1051 ScratchBlock* unsorted = list; 1052 while (unsorted) { 1053 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1054 smallest->next = sorted; 1055 sorted = smallest; 1056 } 1057 list = sorted; 1058 } 1059 1060 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1061 size_t max_alloc_words) { 1062 ScratchBlock* res = NULL; 1063 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1064 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1065 sort_scratch_list(res); 1066 return res; 1067 } 1068 1069 void GenCollectedHeap::release_scratch() { 1070 _young_gen->reset_scratch(); 1071 _old_gen->reset_scratch(); 1072 } 1073 1074 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1075 void do_generation(Generation* gen) { 1076 gen->prepare_for_verify(); 1077 } 1078 }; 1079 1080 void GenCollectedHeap::prepare_for_verify() { 1081 ensure_parsability(false); // no need to retire TLABs 1082 GenPrepareForVerifyClosure blk; 1083 generation_iterate(&blk, false); 1084 } 1085 1086 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1087 bool old_to_young) { 1088 if (old_to_young) { 1089 cl->do_generation(_old_gen); 1090 cl->do_generation(_young_gen); 1091 } else { 1092 cl->do_generation(_young_gen); 1093 cl->do_generation(_old_gen); 1094 } 1095 } 1096 1097 void GenCollectedHeap::space_iterate(SpaceClosure* cl) { 1098 _young_gen->space_iterate(cl, true); 1099 _old_gen->space_iterate(cl, true); 1100 } 1101 1102 bool GenCollectedHeap::is_maximal_no_gc() const { 1103 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1104 } 1105 1106 void GenCollectedHeap::save_marks() { 1107 _young_gen->save_marks(); 1108 _old_gen->save_marks(); 1109 } 1110 1111 GenCollectedHeap* GenCollectedHeap::heap() { 1112 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1113 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap"); 1114 return _gch; 1115 } 1116 1117 1118 void GenCollectedHeap::prepare_for_compaction() { 1119 guarantee(_n_gens = 2, "Wrong number of generations"); 1120 // Start by compacting into same gen. 1121 CompactPoint cp(_old_gen); 1122 _old_gen->prepare_for_compaction(&cp); 1123 _young_gen->prepare_for_compaction(&cp); 1124 } 1125 1126 GCStats* GenCollectedHeap::gc_stats(int level) const { 1127 if (level == 0) { 1128 return _young_gen->gc_stats(); 1129 } else { 1130 return _old_gen->gc_stats(); 1131 } 1132 } 1133 1134 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) { 1135 if (!silent) { 1136 gclog_or_tty->print("%s", _old_gen->name()); 1137 gclog_or_tty->print(" "); 1138 } 1139 _old_gen->verify(); 1140 1141 if (!silent) { 1142 gclog_or_tty->print("%s", _young_gen->name()); 1143 gclog_or_tty->print(" "); 1144 } 1145 _young_gen->verify(); 1146 1147 if (!silent) { 1148 gclog_or_tty->print("remset "); 1149 } 1150 rem_set()->verify(); 1151 } 1152 1153 void GenCollectedHeap::print_on(outputStream* st) const { 1154 _young_gen->print_on(st); 1155 _old_gen->print_on(st); 1156 MetaspaceAux::print_on(st); 1157 } 1158 1159 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1160 if (workers() != NULL) { 1161 workers()->threads_do(tc); 1162 } 1163 #if INCLUDE_ALL_GCS 1164 if (UseConcMarkSweepGC) { 1165 ConcurrentMarkSweepThread::threads_do(tc); 1166 } 1167 #endif // INCLUDE_ALL_GCS 1168 } 1169 1170 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1171 #if INCLUDE_ALL_GCS 1172 if (UseConcMarkSweepGC) { 1173 workers()->print_worker_threads_on(st); 1174 ConcurrentMarkSweepThread::print_all_on(st); 1175 } 1176 #endif // INCLUDE_ALL_GCS 1177 } 1178 1179 void GenCollectedHeap::print_on_error(outputStream* st) const { 1180 this->CollectedHeap::print_on_error(st); 1181 1182 #if INCLUDE_ALL_GCS 1183 if (UseConcMarkSweepGC) { 1184 st->cr(); 1185 CMSCollector::print_on_error(st); 1186 } 1187 #endif // INCLUDE_ALL_GCS 1188 } 1189 1190 void GenCollectedHeap::print_tracing_info() const { 1191 if (TraceYoungGenTime) { 1192 _young_gen->print_summary_info(); 1193 } 1194 if (TraceOldGenTime) { 1195 _old_gen->print_summary_info(); 1196 } 1197 } 1198 1199 void GenCollectedHeap::print_heap_change(size_t prev_used) const { 1200 if (PrintGCDetails && Verbose) { 1201 gclog_or_tty->print(" " SIZE_FORMAT 1202 "->" SIZE_FORMAT 1203 "(" SIZE_FORMAT ")", 1204 prev_used, used(), capacity()); 1205 } else { 1206 gclog_or_tty->print(" " SIZE_FORMAT "K" 1207 "->" SIZE_FORMAT "K" 1208 "(" SIZE_FORMAT "K)", 1209 prev_used / K, used() / K, capacity() / K); 1210 } 1211 } 1212 1213 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1214 private: 1215 bool _full; 1216 public: 1217 void do_generation(Generation* gen) { 1218 gen->gc_prologue(_full); 1219 } 1220 GenGCPrologueClosure(bool full) : _full(full) {}; 1221 }; 1222 1223 void GenCollectedHeap::gc_prologue(bool full) { 1224 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1225 1226 always_do_update_barrier = false; 1227 // Fill TLAB's and such 1228 CollectedHeap::accumulate_statistics_all_tlabs(); 1229 ensure_parsability(true); // retire TLABs 1230 1231 // Walk generations 1232 GenGCPrologueClosure blk(full); 1233 generation_iterate(&blk, false); // not old-to-young. 1234 }; 1235 1236 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1237 private: 1238 bool _full; 1239 public: 1240 void do_generation(Generation* gen) { 1241 gen->gc_epilogue(_full); 1242 } 1243 GenGCEpilogueClosure(bool full) : _full(full) {}; 1244 }; 1245 1246 void GenCollectedHeap::gc_epilogue(bool full) { 1247 #ifdef COMPILER2 1248 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1249 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1250 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1251 #endif /* COMPILER2 */ 1252 1253 resize_all_tlabs(); 1254 1255 GenGCEpilogueClosure blk(full); 1256 generation_iterate(&blk, false); // not old-to-young. 1257 1258 if (!CleanChunkPoolAsync) { 1259 Chunk::clean_chunk_pool(); 1260 } 1261 1262 MetaspaceCounters::update_performance_counters(); 1263 CompressedClassSpaceCounters::update_performance_counters(); 1264 1265 always_do_update_barrier = UseConcMarkSweepGC; 1266 }; 1267 1268 #ifndef PRODUCT 1269 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1270 private: 1271 public: 1272 void do_generation(Generation* gen) { 1273 gen->record_spaces_top(); 1274 } 1275 }; 1276 1277 void GenCollectedHeap::record_gen_tops_before_GC() { 1278 if (ZapUnusedHeapArea) { 1279 GenGCSaveTopsBeforeGCClosure blk; 1280 generation_iterate(&blk, false); // not old-to-young. 1281 } 1282 } 1283 #endif // not PRODUCT 1284 1285 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1286 public: 1287 void do_generation(Generation* gen) { 1288 gen->ensure_parsability(); 1289 } 1290 }; 1291 1292 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1293 CollectedHeap::ensure_parsability(retire_tlabs); 1294 GenEnsureParsabilityClosure ep_cl; 1295 generation_iterate(&ep_cl, false); 1296 } 1297 1298 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1299 oop obj, 1300 size_t obj_size) { 1301 guarantee(old_gen->level() == 1, "We only get here with an old generation"); 1302 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1303 HeapWord* result = NULL; 1304 1305 result = old_gen->expand_and_allocate(obj_size, false); 1306 1307 if (result != NULL) { 1308 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1309 } 1310 return oop(result); 1311 } 1312 1313 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1314 jlong _time; // in ms 1315 jlong _now; // in ms 1316 1317 public: 1318 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1319 1320 jlong time() { return _time; } 1321 1322 void do_generation(Generation* gen) { 1323 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1324 } 1325 }; 1326 1327 jlong GenCollectedHeap::millis_since_last_gc() { 1328 // We need a monotonically non-decreasing time in ms but 1329 // os::javaTimeMillis() does not guarantee monotonicity. 1330 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1331 GenTimeOfLastGCClosure tolgc_cl(now); 1332 // iterate over generations getting the oldest 1333 // time that a generation was collected 1334 generation_iterate(&tolgc_cl, false); 1335 1336 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1337 // provided the underlying platform provides such a time source 1338 // (and it is bug free). So we still have to guard against getting 1339 // back a time later than 'now'. 1340 jlong retVal = now - tolgc_cl.time(); 1341 if (retVal < 0) { 1342 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);) 1343 return 0; 1344 } 1345 return retVal; 1346 }