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/strongRootsScope.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 if (UseConcMarkSweepGC) { 89 _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads, 90 /* are_GC_task_threads */true, 91 /* are_ConcurrentGC_threads */false); 92 _workers->initialize_workers(); 93 } else { 94 _workers = NULL; 95 } 96 } 97 98 jint GenCollectedHeap::initialize() { 99 CollectedHeap::pre_initialize(); 100 101 _n_gens = gen_policy()->number_of_generations(); 102 assert(_n_gens == 2, "There is no support for more than two generations"); 103 104 // While there are no constraints in the GC code that HeapWordSize 105 // be any particular value, there are multiple other areas in the 106 // system which believe this to be true (e.g. oop->object_size in some 107 // cases incorrectly returns the size in wordSize units rather than 108 // HeapWordSize). 109 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 110 111 // Allocate space for the heap. 112 113 char* heap_address; 114 ReservedSpace heap_rs; 115 116 size_t heap_alignment = collector_policy()->heap_alignment(); 117 118 heap_address = allocate(heap_alignment, &heap_rs); 119 120 if (!heap_rs.is_reserved()) { 121 vm_shutdown_during_initialization( 122 "Could not reserve enough space for object heap"); 123 return JNI_ENOMEM; 124 } 125 126 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 127 128 _rem_set = collector_policy()->create_rem_set(reserved_region()); 129 _barrier_set = rem_set()->bs(); 130 oopDesc::set_bs(_barrier_set); 131 132 _gch = this; 133 134 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false); 135 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set()); 136 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size()); 137 138 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false); 139 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set()); 140 clear_incremental_collection_failed(); 141 142 #if INCLUDE_ALL_GCS 143 // If we are running CMS, create the collector responsible 144 // for collecting the CMS generations. 145 if (collector_policy()->is_concurrent_mark_sweep_policy()) { 146 bool success = create_cms_collector(); 147 if (!success) return JNI_ENOMEM; 148 } 149 #endif // INCLUDE_ALL_GCS 150 151 return JNI_OK; 152 } 153 154 char* GenCollectedHeap::allocate(size_t alignment, 155 ReservedSpace* heap_rs){ 156 // Now figure out the total size. 157 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 158 assert(alignment % pageSize == 0, "Must be"); 159 160 GenerationSpec* young_spec = gen_policy()->young_gen_spec(); 161 GenerationSpec* old_spec = gen_policy()->old_gen_spec(); 162 163 // Check for overflow. 164 size_t total_reserved = young_spec->max_size() + old_spec->max_size(); 165 if (total_reserved < young_spec->max_size()) { 166 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 167 "the maximum representable size"); 168 } 169 assert(total_reserved % alignment == 0, 170 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 171 SIZE_FORMAT, total_reserved, alignment)); 172 173 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 174 return heap_rs->base(); 175 } 176 177 void GenCollectedHeap::post_initialize() { 178 CollectedHeap::post_initialize(); 179 ref_processing_init(); 180 GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy(); 181 guarantee(policy->is_generation_policy(), "Illegal policy type"); 182 assert((_young_gen->kind() == Generation::DefNew) || 183 (_young_gen->kind() == Generation::ParNew), 184 "Wrong youngest generation type"); 185 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 186 187 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep || 188 _old_gen->kind() == Generation::MarkSweepCompact, 189 "Wrong generation kind"); 190 191 policy->initialize_size_policy(def_new_gen->eden()->capacity(), 192 _old_gen->capacity(), 193 def_new_gen->from()->capacity()); 194 policy->initialize_gc_policy_counters(); 195 } 196 197 void GenCollectedHeap::ref_processing_init() { 198 _young_gen->ref_processor_init(); 199 _old_gen->ref_processor_init(); 200 } 201 202 size_t GenCollectedHeap::capacity() const { 203 return _young_gen->capacity() + _old_gen->capacity(); 204 } 205 206 size_t GenCollectedHeap::used() const { 207 return _young_gen->used() + _old_gen->used(); 208 } 209 210 // Save the "used_region" for generations level and lower. 211 void GenCollectedHeap::save_used_regions(int level) { 212 assert(level >= 0, "Illegal level parameter"); 213 assert(level < _n_gens, "Illegal level parameter"); 214 if (level == 1) { 215 _old_gen->save_used_region(); 216 } 217 _young_gen->save_used_region(); 218 } 219 220 size_t GenCollectedHeap::max_capacity() const { 221 return _young_gen->max_capacity() + _old_gen->max_capacity(); 222 } 223 224 // Update the _full_collections_completed counter 225 // at the end of a stop-world full GC. 226 unsigned int GenCollectedHeap::update_full_collections_completed() { 227 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 228 assert(_full_collections_completed <= _total_full_collections, 229 "Can't complete more collections than were started"); 230 _full_collections_completed = _total_full_collections; 231 ml.notify_all(); 232 return _full_collections_completed; 233 } 234 235 // Update the _full_collections_completed counter, as appropriate, 236 // at the end of a concurrent GC cycle. Note the conditional update 237 // below to allow this method to be called by a concurrent collector 238 // without synchronizing in any manner with the VM thread (which 239 // may already have initiated a STW full collection "concurrently"). 240 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 241 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 242 assert((_full_collections_completed <= _total_full_collections) && 243 (count <= _total_full_collections), 244 "Can't complete more collections than were started"); 245 if (count > _full_collections_completed) { 246 _full_collections_completed = count; 247 ml.notify_all(); 248 } 249 return _full_collections_completed; 250 } 251 252 253 #ifndef PRODUCT 254 // Override of memory state checking method in CollectedHeap: 255 // Some collectors (CMS for example) can't have badHeapWordVal written 256 // in the first two words of an object. (For instance , in the case of 257 // CMS these words hold state used to synchronize between certain 258 // (concurrent) GC steps and direct allocating mutators.) 259 // The skip_header_HeapWords() method below, allows us to skip 260 // over the requisite number of HeapWord's. Note that (for 261 // generational collectors) this means that those many words are 262 // skipped in each object, irrespective of the generation in which 263 // that object lives. The resultant loss of precision seems to be 264 // harmless and the pain of avoiding that imprecision appears somewhat 265 // higher than we are prepared to pay for such rudimentary debugging 266 // support. 267 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 268 size_t size) { 269 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 270 // We are asked to check a size in HeapWords, 271 // but the memory is mangled in juint words. 272 juint* start = (juint*) (addr + skip_header_HeapWords()); 273 juint* end = (juint*) (addr + size); 274 for (juint* slot = start; slot < end; slot += 1) { 275 assert(*slot == badHeapWordVal, 276 "Found non badHeapWordValue in pre-allocation check"); 277 } 278 } 279 } 280 #endif 281 282 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 283 bool is_tlab, 284 bool first_only) { 285 HeapWord* res = NULL; 286 287 if (_young_gen->should_allocate(size, is_tlab)) { 288 res = _young_gen->allocate(size, is_tlab); 289 if (res != NULL || first_only) { 290 return res; 291 } 292 } 293 294 if (_old_gen->should_allocate(size, is_tlab)) { 295 res = _old_gen->allocate(size, is_tlab); 296 } 297 298 return res; 299 } 300 301 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 302 bool* gc_overhead_limit_was_exceeded) { 303 return collector_policy()->mem_allocate_work(size, 304 false /* is_tlab */, 305 gc_overhead_limit_was_exceeded); 306 } 307 308 bool GenCollectedHeap::must_clear_all_soft_refs() { 309 return _gc_cause == GCCause::_last_ditch_collection; 310 } 311 312 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 313 return UseConcMarkSweepGC && 314 ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) || 315 (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent)); 316 } 317 318 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 319 bool is_tlab, bool run_verification, bool clear_soft_refs, 320 bool restore_marks_for_biased_locking) { 321 // Timer for individual generations. Last argument is false: no CR 322 // FIXME: We should try to start the timing earlier to cover more of the GC pause 323 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 324 // so we can assume here that the next GC id is what we want. 325 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek()); 326 TraceCollectorStats tcs(gen->counters()); 327 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 328 329 size_t prev_used = gen->used(); 330 gen->stat_record()->invocations++; 331 gen->stat_record()->accumulated_time.start(); 332 333 // Must be done anew before each collection because 334 // a previous collection will do mangling and will 335 // change top of some spaces. 336 record_gen_tops_before_GC(); 337 338 if (PrintGC && Verbose) { 339 gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT, 340 gen->level(), 341 gen->stat_record()->invocations, 342 size * HeapWordSize); 343 } 344 345 if (run_verification && VerifyBeforeGC) { 346 HandleMark hm; // Discard invalid handles created during verification 347 Universe::verify(" VerifyBeforeGC:"); 348 } 349 COMPILER2_PRESENT(DerivedPointerTable::clear()); 350 351 if (restore_marks_for_biased_locking) { 352 // We perform this mark word preservation work lazily 353 // because it's only at this point that we know whether we 354 // absolutely have to do it; we want to avoid doing it for 355 // scavenge-only collections where it's unnecessary 356 BiasedLocking::preserve_marks(); 357 } 358 359 // Do collection work 360 { 361 // Note on ref discovery: For what appear to be historical reasons, 362 // GCH enables and disabled (by enqueing) refs discovery. 363 // In the future this should be moved into the generation's 364 // collect method so that ref discovery and enqueueing concerns 365 // are local to a generation. The collect method could return 366 // an appropriate indication in the case that notification on 367 // the ref lock was needed. This will make the treatment of 368 // weak refs more uniform (and indeed remove such concerns 369 // from GCH). XXX 370 371 HandleMark hm; // Discard invalid handles created during gc 372 save_marks(); // save marks for all gens 373 // We want to discover references, but not process them yet. 374 // This mode is disabled in process_discovered_references if the 375 // generation does some collection work, or in 376 // enqueue_discovered_references if the generation returns 377 // without doing any work. 378 ReferenceProcessor* rp = gen->ref_processor(); 379 // If the discovery of ("weak") refs in this generation is 380 // atomic wrt other collectors in this configuration, we 381 // are guaranteed to have empty discovered ref lists. 382 if (rp->discovery_is_atomic()) { 383 rp->enable_discovery(); 384 rp->setup_policy(clear_soft_refs); 385 } else { 386 // collect() below will enable discovery as appropriate 387 } 388 gen->collect(full, clear_soft_refs, size, is_tlab); 389 if (!rp->enqueuing_is_done()) { 390 rp->enqueue_discovered_references(); 391 } else { 392 rp->set_enqueuing_is_done(false); 393 } 394 rp->verify_no_references_recorded(); 395 } 396 397 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 398 399 gen->stat_record()->accumulated_time.stop(); 400 401 update_gc_stats(gen->level(), full); 402 403 if (run_verification && VerifyAfterGC) { 404 HandleMark hm; // Discard invalid handles created during verification 405 Universe::verify(" VerifyAfterGC:"); 406 } 407 408 if (PrintGCDetails) { 409 gclog_or_tty->print(":"); 410 gen->print_heap_change(prev_used); 411 } 412 } 413 414 void GenCollectedHeap::do_collection(bool full, 415 bool clear_all_soft_refs, 416 size_t size, 417 bool is_tlab, 418 int max_level) { 419 ResourceMark rm; 420 DEBUG_ONLY(Thread* my_thread = Thread::current();) 421 422 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 423 assert(my_thread->is_VM_thread() || 424 my_thread->is_ConcurrentGC_thread(), 425 "incorrect thread type capability"); 426 assert(Heap_lock->is_locked(), 427 "the requesting thread should have the Heap_lock"); 428 guarantee(!is_gc_active(), "collection is not reentrant"); 429 assert(max_level < n_gens(), "sanity check"); 430 431 if (GC_locker::check_active_before_gc()) { 432 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 433 } 434 435 const bool do_clear_all_soft_refs = clear_all_soft_refs || 436 collector_policy()->should_clear_all_soft_refs(); 437 438 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 439 440 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 441 442 print_heap_before_gc(); 443 444 { 445 FlagSetting fl(_is_gc_active, true); 446 447 bool complete = full && (max_level == (n_gens()-1)); 448 const char* gc_cause_prefix = complete ? "Full GC" : "GC"; 449 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 450 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 451 // so we can assume here that the next GC id is what we want. 452 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek()); 453 454 gc_prologue(complete); 455 increment_total_collections(complete); 456 457 size_t gch_prev_used = used(); 458 bool run_verification = total_collections() >= VerifyGCStartAt; 459 460 bool prepared_for_verification = false; 461 int max_level_collected = 0; 462 bool old_collects_young = (max_level == 1) && 463 full && 464 _old_gen->full_collects_younger_generations(); 465 if (!old_collects_young && 466 _young_gen->should_collect(full, size, is_tlab)) { 467 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 468 prepare_for_verify(); 469 prepared_for_verification = true; 470 } 471 472 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking"); 473 collect_generation(_young_gen, 474 full, 475 size, 476 is_tlab, 477 run_verification && VerifyGCLevel <= 0, 478 do_clear_all_soft_refs, 479 false); 480 481 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 482 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 483 // Allocation request was met by young GC. 484 size = 0; 485 } 486 } 487 488 bool must_restore_marks_for_biased_locking = false; 489 490 if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) { 491 if (!complete) { 492 // The full_collections increment was missed above. 493 increment_total_full_collections(); 494 } 495 496 pre_full_gc_dump(NULL); // do any pre full gc dumps 497 498 if (!prepared_for_verification && run_verification && 499 VerifyGCLevel <= 1 && VerifyBeforeGC) { 500 prepare_for_verify(); 501 } 502 503 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking"); 504 collect_generation(_old_gen, 505 full, 506 size, 507 is_tlab, 508 run_verification && VerifyGCLevel <= 1, 509 do_clear_all_soft_refs, 510 true); 511 512 must_restore_marks_for_biased_locking = true; 513 max_level_collected = 1; 514 } 515 516 // Update "complete" boolean wrt what actually transpired -- 517 // for instance, a promotion failure could have led to 518 // a whole heap collection. 519 complete = complete || (max_level_collected == n_gens() - 1); 520 521 if (complete) { // We did a "major" collection 522 // FIXME: See comment at pre_full_gc_dump call 523 post_full_gc_dump(NULL); // do any post full gc dumps 524 } 525 526 if (PrintGCDetails) { 527 print_heap_change(gch_prev_used); 528 529 // Print metaspace info for full GC with PrintGCDetails flag. 530 if (complete) { 531 MetaspaceAux::print_metaspace_change(metadata_prev_used); 532 } 533 } 534 535 // Adjust generation sizes. 536 if (max_level_collected == 1) { 537 _old_gen->compute_new_size(); 538 } 539 _young_gen->compute_new_size(); 540 541 if (complete) { 542 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 543 ClassLoaderDataGraph::purge(); 544 MetaspaceAux::verify_metrics(); 545 // Resize the metaspace capacity after full collections 546 MetaspaceGC::compute_new_size(); 547 update_full_collections_completed(); 548 } 549 550 // Track memory usage and detect low memory after GC finishes 551 MemoryService::track_memory_usage(); 552 553 gc_epilogue(complete); 554 555 if (must_restore_marks_for_biased_locking) { 556 BiasedLocking::restore_marks(); 557 } 558 } 559 560 print_heap_after_gc(); 561 562 #ifdef TRACESPINNING 563 ParallelTaskTerminator::print_termination_counts(); 564 #endif 565 } 566 567 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 568 return collector_policy()->satisfy_failed_allocation(size, is_tlab); 569 } 570 571 void GenCollectedHeap::set_par_threads(uint t) { 572 assert(t == 0 || !UseSerialGC, "Cannot have parallel threads"); 573 CollectedHeap::set_par_threads(t); 574 set_n_termination(t); 575 } 576 577 void GenCollectedHeap::set_n_termination(uint t) { 578 _process_strong_tasks->set_n_threads(t); 579 } 580 581 #ifdef ASSERT 582 class AssertNonScavengableClosure: public OopClosure { 583 public: 584 virtual void do_oop(oop* p) { 585 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 586 "Referent should not be scavengable."); } 587 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 588 }; 589 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 590 #endif 591 592 void GenCollectedHeap::process_roots(bool activate_scope, 593 ScanningOption so, 594 OopClosure* strong_roots, 595 OopClosure* weak_roots, 596 CLDClosure* strong_cld_closure, 597 CLDClosure* weak_cld_closure, 598 CodeBlobClosure* code_roots) { 599 StrongRootsScope srs(activate_scope); 600 601 // General roots. 602 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 603 assert(code_roots != NULL, "code root closure should always be set"); 604 // _n_termination for _process_strong_tasks should be set up stream 605 // in a method not running in a GC worker. Otherwise the GC worker 606 // could be trying to change the termination condition while the task 607 // is executing in another GC worker. 608 609 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 610 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 611 } 612 613 // Some CLDs contained in the thread frames should be considered strong. 614 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 615 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 616 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 617 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 618 619 bool is_par =n_par_threads() > 0; 620 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p); 621 622 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 623 Universe::oops_do(strong_roots); 624 } 625 // Global (strong) JNI handles 626 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 627 JNIHandles::oops_do(strong_roots); 628 } 629 630 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 631 ObjectSynchronizer::oops_do(strong_roots); 632 } 633 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 634 FlatProfiler::oops_do(strong_roots); 635 } 636 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 637 Management::oops_do(strong_roots); 638 } 639 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 640 JvmtiExport::oops_do(strong_roots); 641 } 642 643 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 644 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 645 } 646 647 // All threads execute the following. A specific chunk of buckets 648 // from the StringTable are the individual tasks. 649 if (weak_roots != NULL) { 650 if (CollectedHeap::use_parallel_gc_threads()) { 651 StringTable::possibly_parallel_oops_do(weak_roots); 652 } else { 653 StringTable::oops_do(weak_roots); 654 } 655 } 656 657 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 658 if (so & SO_ScavengeCodeCache) { 659 assert(code_roots != NULL, "must supply closure for code cache"); 660 661 // We only visit parts of the CodeCache when scavenging. 662 CodeCache::scavenge_root_nmethods_do(code_roots); 663 } 664 if (so & SO_AllCodeCache) { 665 assert(code_roots != NULL, "must supply closure for code cache"); 666 667 // CMSCollector uses this to do intermediate-strength collections. 668 // We scan the entire code cache, since CodeCache::do_unloading is not called. 669 CodeCache::blobs_do(code_roots); 670 } 671 // Verify that the code cache contents are not subject to 672 // movement by a scavenging collection. 673 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 674 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 675 } 676 677 } 678 679 void GenCollectedHeap::gen_process_roots(int level, 680 bool younger_gens_as_roots, 681 bool activate_scope, 682 ScanningOption so, 683 bool only_strong_roots, 684 OopsInGenClosure* not_older_gens, 685 OopsInGenClosure* older_gens, 686 CLDClosure* cld_closure) { 687 const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots; 688 689 bool is_moving_collection = false; 690 if (level == 0 || is_adjust_phase) { 691 // young collections are always moving 692 is_moving_collection = true; 693 } 694 695 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection); 696 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens; 697 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 698 699 process_roots(activate_scope, so, 700 not_older_gens, weak_roots, 701 cld_closure, weak_cld_closure, 702 &mark_code_closure); 703 704 if (younger_gens_as_roots) { 705 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 706 if (level == 1) { 707 not_older_gens->set_generation(_young_gen); 708 _young_gen->oop_iterate(not_older_gens); 709 } 710 not_older_gens->reset_generation(); 711 } 712 } 713 // When collection is parallel, all threads get to cooperate to do 714 // older-gen scanning. 715 if (level == 0) { 716 older_gens->set_generation(_old_gen); 717 rem_set()->younger_refs_iterate(_old_gen, older_gens); 718 older_gens->reset_generation(); 719 } 720 721 _process_strong_tasks->all_tasks_completed(); 722 } 723 724 725 class AlwaysTrueClosure: public BoolObjectClosure { 726 public: 727 bool do_object_b(oop p) { return true; } 728 }; 729 static AlwaysTrueClosure always_true; 730 731 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 732 JNIHandles::weak_oops_do(&always_true, root_closure); 733 _young_gen->ref_processor()->weak_oops_do(root_closure); 734 _old_gen->ref_processor()->weak_oops_do(root_closure); 735 } 736 737 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 738 void GenCollectedHeap:: \ 739 oop_since_save_marks_iterate(int level, \ 740 OopClosureType* cur, \ 741 OopClosureType* older) { \ 742 if (level == 0) { \ 743 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 744 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 745 } else { \ 746 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 747 } \ 748 } 749 750 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 751 752 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 753 754 bool GenCollectedHeap::no_allocs_since_save_marks(int level) { 755 if (level == 0 && !_young_gen->no_allocs_since_save_marks()) { 756 return false; 757 } 758 return _old_gen->no_allocs_since_save_marks(); 759 } 760 761 bool GenCollectedHeap::supports_inline_contig_alloc() const { 762 return _young_gen->supports_inline_contig_alloc(); 763 } 764 765 HeapWord** GenCollectedHeap::top_addr() const { 766 return _young_gen->top_addr(); 767 } 768 769 HeapWord** GenCollectedHeap::end_addr() const { 770 return _young_gen->end_addr(); 771 } 772 773 // public collection interfaces 774 775 void GenCollectedHeap::collect(GCCause::Cause cause) { 776 if (should_do_concurrent_full_gc(cause)) { 777 #if INCLUDE_ALL_GCS 778 // mostly concurrent full collection 779 collect_mostly_concurrent(cause); 780 #else // INCLUDE_ALL_GCS 781 ShouldNotReachHere(); 782 #endif // INCLUDE_ALL_GCS 783 } else if (cause == GCCause::_wb_young_gc) { 784 // minor collection for WhiteBox API 785 collect(cause, 0); 786 } else { 787 #ifdef ASSERT 788 if (cause == GCCause::_scavenge_alot) { 789 // minor collection only 790 collect(cause, 0); 791 } else { 792 // Stop-the-world full collection 793 collect(cause, n_gens() - 1); 794 } 795 #else 796 // Stop-the-world full collection 797 collect(cause, n_gens() - 1); 798 #endif 799 } 800 } 801 802 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) { 803 // The caller doesn't have the Heap_lock 804 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 805 MutexLocker ml(Heap_lock); 806 collect_locked(cause, max_level); 807 } 808 809 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 810 // The caller has the Heap_lock 811 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 812 collect_locked(cause, n_gens() - 1); 813 } 814 815 // this is the private collection interface 816 // The Heap_lock is expected to be held on entry. 817 818 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) { 819 // Read the GC count while holding the Heap_lock 820 unsigned int gc_count_before = total_collections(); 821 unsigned int full_gc_count_before = total_full_collections(); 822 { 823 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 824 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 825 cause, max_level); 826 VMThread::execute(&op); 827 } 828 } 829 830 #if INCLUDE_ALL_GCS 831 bool GenCollectedHeap::create_cms_collector() { 832 833 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 834 "Unexpected generation kinds"); 835 // Skip two header words in the block content verification 836 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 837 CMSCollector* collector = new CMSCollector( 838 (ConcurrentMarkSweepGeneration*)_old_gen, 839 _rem_set->as_CardTableRS(), 840 (ConcurrentMarkSweepPolicy*) collector_policy()); 841 842 if (collector == NULL || !collector->completed_initialization()) { 843 if (collector) { 844 delete collector; // Be nice in embedded situation 845 } 846 vm_shutdown_during_initialization("Could not create CMS collector"); 847 return false; 848 } 849 return true; // success 850 } 851 852 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 853 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 854 855 MutexLocker ml(Heap_lock); 856 // Read the GC counts while holding the Heap_lock 857 unsigned int full_gc_count_before = total_full_collections(); 858 unsigned int gc_count_before = total_collections(); 859 { 860 MutexUnlocker mu(Heap_lock); 861 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 862 VMThread::execute(&op); 863 } 864 } 865 #endif // INCLUDE_ALL_GCS 866 867 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 868 do_full_collection(clear_all_soft_refs, _n_gens - 1); 869 } 870 871 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 872 int max_level) { 873 int local_max_level; 874 if (!incremental_collection_will_fail(false /* don't consult_young */) && 875 gc_cause() == GCCause::_gc_locker) { 876 local_max_level = 0; 877 } else { 878 local_max_level = max_level; 879 } 880 881 do_collection(true /* full */, 882 clear_all_soft_refs /* clear_all_soft_refs */, 883 0 /* size */, 884 false /* is_tlab */, 885 local_max_level /* max_level */); 886 // Hack XXX FIX ME !!! 887 // A scavenge may not have been attempted, or may have 888 // been attempted and failed, because the old gen was too full 889 if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker && 890 incremental_collection_will_fail(false /* don't consult_young */)) { 891 if (PrintGCDetails) { 892 gclog_or_tty->print_cr("GC locker: Trying a full collection " 893 "because scavenge failed"); 894 } 895 // This time allow the old gen to be collected as well 896 do_collection(true /* full */, 897 clear_all_soft_refs /* clear_all_soft_refs */, 898 0 /* size */, 899 false /* is_tlab */, 900 n_gens() - 1 /* max_level */); 901 } 902 } 903 904 bool GenCollectedHeap::is_in_young(oop p) { 905 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 906 assert(result == _young_gen->is_in_reserved(p), 907 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p))); 908 return result; 909 } 910 911 // Returns "TRUE" iff "p" points into the committed areas of the heap. 912 bool GenCollectedHeap::is_in(const void* p) const { 913 #ifndef ASSERT 914 guarantee(VerifyBeforeGC || 915 VerifyDuringGC || 916 VerifyBeforeExit || 917 VerifyDuringStartup || 918 PrintAssembly || 919 tty->count() != 0 || // already printing 920 VerifyAfterGC || 921 VMError::fatal_error_in_progress(), "too expensive"); 922 923 #endif 924 return _young_gen->is_in(p) || _old_gen->is_in(p); 925 } 926 927 #ifdef ASSERT 928 // Don't implement this by using is_in_young(). This method is used 929 // in some cases to check that is_in_young() is correct. 930 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 931 assert(is_in_reserved(p) || p == NULL, 932 "Does not work if address is non-null and outside of the heap"); 933 return p < _young_gen->reserved().end() && p != NULL; 934 } 935 #endif 936 937 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 938 _young_gen->oop_iterate(cl); 939 _old_gen->oop_iterate(cl); 940 } 941 942 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 943 _young_gen->object_iterate(cl); 944 _old_gen->object_iterate(cl); 945 } 946 947 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 948 _young_gen->safe_object_iterate(cl); 949 _old_gen->safe_object_iterate(cl); 950 } 951 952 Space* GenCollectedHeap::space_containing(const void* addr) const { 953 Space* res = _young_gen->space_containing(addr); 954 if (res != NULL) { 955 return res; 956 } 957 res = _old_gen->space_containing(addr); 958 assert(res != NULL, "Could not find containing space"); 959 return res; 960 } 961 962 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 963 assert(is_in_reserved(addr), "block_start of address outside of heap"); 964 if (_young_gen->is_in_reserved(addr)) { 965 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 966 return _young_gen->block_start(addr); 967 } 968 969 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 970 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 971 return _old_gen->block_start(addr); 972 } 973 974 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 975 assert(is_in_reserved(addr), "block_size of address outside of heap"); 976 if (_young_gen->is_in_reserved(addr)) { 977 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 978 return _young_gen->block_size(addr); 979 } 980 981 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 982 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 983 return _old_gen->block_size(addr); 984 } 985 986 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 987 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 988 assert(block_start(addr) == addr, "addr must be a block start"); 989 if (_young_gen->is_in_reserved(addr)) { 990 return _young_gen->block_is_obj(addr); 991 } 992 993 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 994 return _old_gen->block_is_obj(addr); 995 } 996 997 bool GenCollectedHeap::supports_tlab_allocation() const { 998 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 999 return _young_gen->supports_tlab_allocation(); 1000 } 1001 1002 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 1003 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1004 if (_young_gen->supports_tlab_allocation()) { 1005 return _young_gen->tlab_capacity(); 1006 } 1007 return 0; 1008 } 1009 1010 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 1011 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1012 if (_young_gen->supports_tlab_allocation()) { 1013 return _young_gen->tlab_used(); 1014 } 1015 return 0; 1016 } 1017 1018 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 1019 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1020 if (_young_gen->supports_tlab_allocation()) { 1021 return _young_gen->unsafe_max_tlab_alloc(); 1022 } 1023 return 0; 1024 } 1025 1026 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 1027 bool gc_overhead_limit_was_exceeded; 1028 return collector_policy()->mem_allocate_work(size /* size */, 1029 true /* is_tlab */, 1030 &gc_overhead_limit_was_exceeded); 1031 } 1032 1033 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1034 // from the list headed by "*prev_ptr". 1035 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1036 bool first = true; 1037 size_t min_size = 0; // "first" makes this conceptually infinite. 1038 ScratchBlock **smallest_ptr, *smallest; 1039 ScratchBlock *cur = *prev_ptr; 1040 while (cur) { 1041 assert(*prev_ptr == cur, "just checking"); 1042 if (first || cur->num_words < min_size) { 1043 smallest_ptr = prev_ptr; 1044 smallest = cur; 1045 min_size = smallest->num_words; 1046 first = false; 1047 } 1048 prev_ptr = &cur->next; 1049 cur = cur->next; 1050 } 1051 smallest = *smallest_ptr; 1052 *smallest_ptr = smallest->next; 1053 return smallest; 1054 } 1055 1056 // Sort the scratch block list headed by res into decreasing size order, 1057 // and set "res" to the result. 1058 static void sort_scratch_list(ScratchBlock*& list) { 1059 ScratchBlock* sorted = NULL; 1060 ScratchBlock* unsorted = list; 1061 while (unsorted) { 1062 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1063 smallest->next = sorted; 1064 sorted = smallest; 1065 } 1066 list = sorted; 1067 } 1068 1069 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1070 size_t max_alloc_words) { 1071 ScratchBlock* res = NULL; 1072 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1073 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1074 sort_scratch_list(res); 1075 return res; 1076 } 1077 1078 void GenCollectedHeap::release_scratch() { 1079 _young_gen->reset_scratch(); 1080 _old_gen->reset_scratch(); 1081 } 1082 1083 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1084 void do_generation(Generation* gen) { 1085 gen->prepare_for_verify(); 1086 } 1087 }; 1088 1089 void GenCollectedHeap::prepare_for_verify() { 1090 ensure_parsability(false); // no need to retire TLABs 1091 GenPrepareForVerifyClosure blk; 1092 generation_iterate(&blk, false); 1093 } 1094 1095 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1096 bool old_to_young) { 1097 if (old_to_young) { 1098 cl->do_generation(_old_gen); 1099 cl->do_generation(_young_gen); 1100 } else { 1101 cl->do_generation(_young_gen); 1102 cl->do_generation(_old_gen); 1103 } 1104 } 1105 1106 bool GenCollectedHeap::is_maximal_no_gc() const { 1107 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1108 } 1109 1110 void GenCollectedHeap::save_marks() { 1111 _young_gen->save_marks(); 1112 _old_gen->save_marks(); 1113 } 1114 1115 GenCollectedHeap* GenCollectedHeap::heap() { 1116 assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1117 assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap"); 1118 return _gch; 1119 } 1120 1121 1122 void GenCollectedHeap::prepare_for_compaction() { 1123 guarantee(_n_gens = 2, "Wrong number of generations"); 1124 // Start by compacting into same gen. 1125 CompactPoint cp(_old_gen); 1126 _old_gen->prepare_for_compaction(&cp); 1127 _young_gen->prepare_for_compaction(&cp); 1128 } 1129 1130 GCStats* GenCollectedHeap::gc_stats(int level) const { 1131 if (level == 0) { 1132 return _young_gen->gc_stats(); 1133 } else { 1134 return _old_gen->gc_stats(); 1135 } 1136 } 1137 1138 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) { 1139 if (!silent) { 1140 gclog_or_tty->print("%s", _old_gen->name()); 1141 gclog_or_tty->print(" "); 1142 } 1143 _old_gen->verify(); 1144 1145 if (!silent) { 1146 gclog_or_tty->print("%s", _young_gen->name()); 1147 gclog_or_tty->print(" "); 1148 } 1149 _young_gen->verify(); 1150 1151 if (!silent) { 1152 gclog_or_tty->print("remset "); 1153 } 1154 rem_set()->verify(); 1155 } 1156 1157 void GenCollectedHeap::print_on(outputStream* st) const { 1158 _young_gen->print_on(st); 1159 _old_gen->print_on(st); 1160 MetaspaceAux::print_on(st); 1161 } 1162 1163 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1164 if (workers() != NULL) { 1165 workers()->threads_do(tc); 1166 } 1167 #if INCLUDE_ALL_GCS 1168 if (UseConcMarkSweepGC) { 1169 ConcurrentMarkSweepThread::threads_do(tc); 1170 } 1171 #endif // INCLUDE_ALL_GCS 1172 } 1173 1174 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1175 #if INCLUDE_ALL_GCS 1176 if (UseConcMarkSweepGC) { 1177 workers()->print_worker_threads_on(st); 1178 ConcurrentMarkSweepThread::print_all_on(st); 1179 } 1180 #endif // INCLUDE_ALL_GCS 1181 } 1182 1183 void GenCollectedHeap::print_on_error(outputStream* st) const { 1184 this->CollectedHeap::print_on_error(st); 1185 1186 #if INCLUDE_ALL_GCS 1187 if (UseConcMarkSweepGC) { 1188 st->cr(); 1189 CMSCollector::print_on_error(st); 1190 } 1191 #endif // INCLUDE_ALL_GCS 1192 } 1193 1194 void GenCollectedHeap::print_tracing_info() const { 1195 if (TraceYoungGenTime) { 1196 _young_gen->print_summary_info(); 1197 } 1198 if (TraceOldGenTime) { 1199 _old_gen->print_summary_info(); 1200 } 1201 } 1202 1203 void GenCollectedHeap::print_heap_change(size_t prev_used) const { 1204 if (PrintGCDetails && Verbose) { 1205 gclog_or_tty->print(" " SIZE_FORMAT 1206 "->" SIZE_FORMAT 1207 "(" SIZE_FORMAT ")", 1208 prev_used, used(), capacity()); 1209 } else { 1210 gclog_or_tty->print(" " SIZE_FORMAT "K" 1211 "->" SIZE_FORMAT "K" 1212 "(" SIZE_FORMAT "K)", 1213 prev_used / K, used() / K, capacity() / K); 1214 } 1215 } 1216 1217 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1218 private: 1219 bool _full; 1220 public: 1221 void do_generation(Generation* gen) { 1222 gen->gc_prologue(_full); 1223 } 1224 GenGCPrologueClosure(bool full) : _full(full) {}; 1225 }; 1226 1227 void GenCollectedHeap::gc_prologue(bool full) { 1228 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1229 1230 always_do_update_barrier = false; 1231 // Fill TLAB's and such 1232 CollectedHeap::accumulate_statistics_all_tlabs(); 1233 ensure_parsability(true); // retire TLABs 1234 1235 // Walk generations 1236 GenGCPrologueClosure blk(full); 1237 generation_iterate(&blk, false); // not old-to-young. 1238 }; 1239 1240 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1241 private: 1242 bool _full; 1243 public: 1244 void do_generation(Generation* gen) { 1245 gen->gc_epilogue(_full); 1246 } 1247 GenGCEpilogueClosure(bool full) : _full(full) {}; 1248 }; 1249 1250 void GenCollectedHeap::gc_epilogue(bool full) { 1251 #ifdef COMPILER2 1252 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1253 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1254 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1255 #endif /* COMPILER2 */ 1256 1257 resize_all_tlabs(); 1258 1259 GenGCEpilogueClosure blk(full); 1260 generation_iterate(&blk, false); // not old-to-young. 1261 1262 if (!CleanChunkPoolAsync) { 1263 Chunk::clean_chunk_pool(); 1264 } 1265 1266 MetaspaceCounters::update_performance_counters(); 1267 CompressedClassSpaceCounters::update_performance_counters(); 1268 1269 always_do_update_barrier = UseConcMarkSweepGC; 1270 }; 1271 1272 #ifndef PRODUCT 1273 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1274 private: 1275 public: 1276 void do_generation(Generation* gen) { 1277 gen->record_spaces_top(); 1278 } 1279 }; 1280 1281 void GenCollectedHeap::record_gen_tops_before_GC() { 1282 if (ZapUnusedHeapArea) { 1283 GenGCSaveTopsBeforeGCClosure blk; 1284 generation_iterate(&blk, false); // not old-to-young. 1285 } 1286 } 1287 #endif // not PRODUCT 1288 1289 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1290 public: 1291 void do_generation(Generation* gen) { 1292 gen->ensure_parsability(); 1293 } 1294 }; 1295 1296 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1297 CollectedHeap::ensure_parsability(retire_tlabs); 1298 GenEnsureParsabilityClosure ep_cl; 1299 generation_iterate(&ep_cl, false); 1300 } 1301 1302 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1303 oop obj, 1304 size_t obj_size) { 1305 guarantee(old_gen->level() == 1, "We only get here with an old generation"); 1306 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1307 HeapWord* result = NULL; 1308 1309 result = old_gen->expand_and_allocate(obj_size, false); 1310 1311 if (result != NULL) { 1312 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1313 } 1314 return oop(result); 1315 } 1316 1317 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1318 jlong _time; // in ms 1319 jlong _now; // in ms 1320 1321 public: 1322 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1323 1324 jlong time() { return _time; } 1325 1326 void do_generation(Generation* gen) { 1327 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1328 } 1329 }; 1330 1331 jlong GenCollectedHeap::millis_since_last_gc() { 1332 // We need a monotonically non-decreasing time in ms but 1333 // os::javaTimeMillis() does not guarantee monotonicity. 1334 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1335 GenTimeOfLastGCClosure tolgc_cl(now); 1336 // iterate over generations getting the oldest 1337 // time that a generation was collected 1338 generation_iterate(&tolgc_cl, false); 1339 1340 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1341 // provided the underlying platform provides such a time source 1342 // (and it is bug free). So we still have to guard against getting 1343 // back a time later than 'now'. 1344 jlong retVal = now - tolgc_cl.time(); 1345 if (retVal < 0) { 1346 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);) 1347 return 0; 1348 } 1349 return retVal; 1350 }