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