1 /* 2 * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "classfile/symbolTable.hpp" 27 #include "classfile/systemDictionary.hpp" 28 #include "classfile/vmSymbols.hpp" 29 #include "code/codeCache.hpp" 30 #include "code/icBuffer.hpp" 31 #include "gc/shared/collectedHeap.inline.hpp" 32 #include "gc/shared/collectorCounters.hpp" 33 #include "gc/shared/gcLocker.inline.hpp" 34 #include "gc/shared/gcTrace.hpp" 35 #include "gc/shared/gcTraceTime.hpp" 36 #include "gc/shared/genCollectedHeap.hpp" 37 #include "gc/shared/genOopClosures.inline.hpp" 38 #include "gc/shared/generationSpec.hpp" 39 #include "gc/shared/space.hpp" 40 #include "gc/shared/strongRootsScope.hpp" 41 #include "gc/shared/vmGCOperations.hpp" 42 #include "gc/shared/workgroup.hpp" 43 #include "memory/filemap.hpp" 44 #include "memory/resourceArea.hpp" 45 #include "oops/oop.inline.hpp" 46 #include "runtime/biasedLocking.hpp" 47 #include "runtime/fprofiler.hpp" 48 #include "runtime/handles.hpp" 49 #include "runtime/handles.inline.hpp" 50 #include "runtime/java.hpp" 51 #include "runtime/vmThread.hpp" 52 #include "services/management.hpp" 53 #include "services/memoryService.hpp" 54 #include "utilities/macros.hpp" 55 #include "utilities/stack.inline.hpp" 56 #include "utilities/vmError.hpp" 57 #if INCLUDE_ALL_GCS 58 #include "gc/cms/concurrentMarkSweepThread.hpp" 59 #include "gc/cms/vmCMSOperations.hpp" 60 #endif // INCLUDE_ALL_GCS 61 62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;) 63 64 // The set of potentially parallel tasks in root scanning. 65 enum GCH_strong_roots_tasks { 66 GCH_PS_Universe_oops_do, 67 GCH_PS_JNIHandles_oops_do, 68 GCH_PS_ObjectSynchronizer_oops_do, 69 GCH_PS_FlatProfiler_oops_do, 70 GCH_PS_Management_oops_do, 71 GCH_PS_SystemDictionary_oops_do, 72 GCH_PS_ClassLoaderDataGraph_oops_do, 73 GCH_PS_jvmti_oops_do, 74 GCH_PS_CodeCache_oops_do, 75 GCH_PS_younger_gens, 76 // Leave this one last. 77 GCH_PS_NumElements 78 }; 79 80 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) : 81 CollectedHeap(), 82 _rem_set(NULL), 83 _gen_policy(policy), 84 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)), 85 _full_collections_completed(0) 86 { 87 assert(policy != NULL, "Sanity check"); 88 if (UseConcMarkSweepGC) { 89 _workers = new WorkGang("GC Thread", ParallelGCThreads, 90 /* are_GC_task_threads */true, 91 /* are_ConcurrentGC_threads */false); 92 _workers->initialize_workers(); 93 } else { 94 // Serial GC does not use workers. 95 _workers = NULL; 96 } 97 } 98 99 jint GenCollectedHeap::initialize() { 100 CollectedHeap::pre_initialize(); 101 102 // While there are no constraints in the GC code that HeapWordSize 103 // be any particular value, there are multiple other areas in the 104 // system which believe this to be true (e.g. oop->object_size in some 105 // cases incorrectly returns the size in wordSize units rather than 106 // HeapWordSize). 107 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 108 109 // Allocate space for the heap. 110 111 char* heap_address; 112 ReservedSpace heap_rs; 113 114 size_t heap_alignment = collector_policy()->heap_alignment(); 115 116 heap_address = allocate(heap_alignment, &heap_rs); 117 118 if (!heap_rs.is_reserved()) { 119 vm_shutdown_during_initialization( 120 "Could not reserve enough space for object heap"); 121 return JNI_ENOMEM; 122 } 123 124 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 125 126 _rem_set = collector_policy()->create_rem_set(reserved_region()); 127 set_barrier_set(rem_set()->bs()); 128 129 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false); 130 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set()); 131 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size()); 132 133 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false); 134 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set()); 135 clear_incremental_collection_failed(); 136 137 #if INCLUDE_ALL_GCS 138 // If we are running CMS, create the collector responsible 139 // for collecting the CMS generations. 140 if (collector_policy()->is_concurrent_mark_sweep_policy()) { 141 bool success = create_cms_collector(); 142 if (!success) return JNI_ENOMEM; 143 } 144 #endif // INCLUDE_ALL_GCS 145 146 return JNI_OK; 147 } 148 149 char* GenCollectedHeap::allocate(size_t alignment, 150 ReservedSpace* heap_rs){ 151 // Now figure out the total size. 152 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 153 assert(alignment % pageSize == 0, "Must be"); 154 155 GenerationSpec* young_spec = gen_policy()->young_gen_spec(); 156 GenerationSpec* old_spec = gen_policy()->old_gen_spec(); 157 158 // Check for overflow. 159 size_t total_reserved = young_spec->max_size() + old_spec->max_size(); 160 if (total_reserved < young_spec->max_size()) { 161 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 162 "the maximum representable size"); 163 } 164 assert(total_reserved % alignment == 0, 165 err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 166 SIZE_FORMAT, total_reserved, alignment)); 167 168 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 169 return heap_rs->base(); 170 } 171 172 void GenCollectedHeap::post_initialize() { 173 CollectedHeap::post_initialize(); 174 ref_processing_init(); 175 assert((_young_gen->kind() == Generation::DefNew) || 176 (_young_gen->kind() == Generation::ParNew), 177 "Wrong youngest generation type"); 178 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 179 180 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep || 181 _old_gen->kind() == Generation::MarkSweepCompact, 182 "Wrong generation kind"); 183 184 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(), 185 _old_gen->capacity(), 186 def_new_gen->from()->capacity()); 187 _gen_policy->initialize_gc_policy_counters(); 188 } 189 190 void GenCollectedHeap::ref_processing_init() { 191 _young_gen->ref_processor_init(); 192 _old_gen->ref_processor_init(); 193 } 194 195 size_t GenCollectedHeap::capacity() const { 196 return _young_gen->capacity() + _old_gen->capacity(); 197 } 198 199 size_t GenCollectedHeap::used() const { 200 return _young_gen->used() + _old_gen->used(); 201 } 202 203 void GenCollectedHeap::save_used_regions() { 204 _old_gen->save_used_region(); 205 _young_gen->save_used_region(); 206 } 207 208 size_t GenCollectedHeap::max_capacity() const { 209 return _young_gen->max_capacity() + _old_gen->max_capacity(); 210 } 211 212 // Update the _full_collections_completed counter 213 // at the end of a stop-world full GC. 214 unsigned int GenCollectedHeap::update_full_collections_completed() { 215 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 216 assert(_full_collections_completed <= _total_full_collections, 217 "Can't complete more collections than were started"); 218 _full_collections_completed = _total_full_collections; 219 ml.notify_all(); 220 return _full_collections_completed; 221 } 222 223 // Update the _full_collections_completed counter, as appropriate, 224 // at the end of a concurrent GC cycle. Note the conditional update 225 // below to allow this method to be called by a concurrent collector 226 // without synchronizing in any manner with the VM thread (which 227 // may already have initiated a STW full collection "concurrently"). 228 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 229 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 230 assert((_full_collections_completed <= _total_full_collections) && 231 (count <= _total_full_collections), 232 "Can't complete more collections than were started"); 233 if (count > _full_collections_completed) { 234 _full_collections_completed = count; 235 ml.notify_all(); 236 } 237 return _full_collections_completed; 238 } 239 240 241 #ifndef PRODUCT 242 // Override of memory state checking method in CollectedHeap: 243 // Some collectors (CMS for example) can't have badHeapWordVal written 244 // in the first two words of an object. (For instance , in the case of 245 // CMS these words hold state used to synchronize between certain 246 // (concurrent) GC steps and direct allocating mutators.) 247 // The skip_header_HeapWords() method below, allows us to skip 248 // over the requisite number of HeapWord's. Note that (for 249 // generational collectors) this means that those many words are 250 // skipped in each object, irrespective of the generation in which 251 // that object lives. The resultant loss of precision seems to be 252 // harmless and the pain of avoiding that imprecision appears somewhat 253 // higher than we are prepared to pay for such rudimentary debugging 254 // support. 255 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 256 size_t size) { 257 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 258 // We are asked to check a size in HeapWords, 259 // but the memory is mangled in juint words. 260 juint* start = (juint*) (addr + skip_header_HeapWords()); 261 juint* end = (juint*) (addr + size); 262 for (juint* slot = start; slot < end; slot += 1) { 263 assert(*slot == badHeapWordVal, 264 "Found non badHeapWordValue in pre-allocation check"); 265 } 266 } 267 } 268 #endif 269 270 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 271 bool is_tlab, 272 bool first_only) { 273 HeapWord* res = NULL; 274 275 if (_young_gen->should_allocate(size, is_tlab)) { 276 res = _young_gen->allocate(size, is_tlab); 277 if (res != NULL || first_only) { 278 return res; 279 } 280 } 281 282 if (_old_gen->should_allocate(size, is_tlab)) { 283 res = _old_gen->allocate(size, is_tlab); 284 } 285 286 return res; 287 } 288 289 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 290 bool* gc_overhead_limit_was_exceeded) { 291 return collector_policy()->mem_allocate_work(size, 292 false /* is_tlab */, 293 gc_overhead_limit_was_exceeded); 294 } 295 296 bool GenCollectedHeap::must_clear_all_soft_refs() { 297 return _gc_cause == GCCause::_last_ditch_collection; 298 } 299 300 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) { 301 if (!UseConcMarkSweepGC) { 302 return false; 303 } 304 305 switch (cause) { 306 case GCCause::_gc_locker: return GCLockerInvokesConcurrent; 307 case GCCause::_java_lang_system_gc: 308 case GCCause::_dcmd_gc_run: return ExplicitGCInvokesConcurrent; 309 default: return false; 310 } 311 } 312 313 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 314 bool is_tlab, bool run_verification, bool clear_soft_refs, 315 bool restore_marks_for_biased_locking) { 316 // Timer for individual generations. Last argument is false: no CR 317 // FIXME: We should try to start the timing earlier to cover more of the GC pause 318 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 319 // so we can assume here that the next GC id is what we want. 320 GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek()); 321 TraceCollectorStats tcs(gen->counters()); 322 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 323 324 size_t prev_used = gen->used(); 325 gen->stat_record()->invocations++; 326 gen->stat_record()->accumulated_time.start(); 327 328 // Must be done anew before each collection because 329 // a previous collection will do mangling and will 330 // change top of some spaces. 331 record_gen_tops_before_GC(); 332 333 if (PrintGC && Verbose) { 334 // I didn't want to change the logging when removing the level concept, 335 // but I guess this logging could say young/old or something instead of 0/1. 336 uint level; 337 if (heap()->is_young_gen(gen)) { 338 level = 0; 339 } else { 340 level = 1; 341 } 342 gclog_or_tty->print("level=%u invoke=%d size=" SIZE_FORMAT, 343 level, 344 gen->stat_record()->invocations, 345 size * HeapWordSize); 346 } 347 348 if (run_verification && VerifyBeforeGC) { 349 HandleMark hm; // Discard invalid handles created during verification 350 Universe::verify(" VerifyBeforeGC:"); 351 } 352 COMPILER2_PRESENT(DerivedPointerTable::clear()); 353 354 if (restore_marks_for_biased_locking) { 355 // We perform this mark word preservation work lazily 356 // because it's only at this point that we know whether we 357 // absolutely have to do it; we want to avoid doing it for 358 // scavenge-only collections where it's unnecessary 359 BiasedLocking::preserve_marks(); 360 } 361 362 // Do collection work 363 { 364 // Note on ref discovery: For what appear to be historical reasons, 365 // GCH enables and disabled (by enqueing) refs discovery. 366 // In the future this should be moved into the generation's 367 // collect method so that ref discovery and enqueueing concerns 368 // are local to a generation. The collect method could return 369 // an appropriate indication in the case that notification on 370 // the ref lock was needed. This will make the treatment of 371 // weak refs more uniform (and indeed remove such concerns 372 // from GCH). XXX 373 374 HandleMark hm; // Discard invalid handles created during gc 375 save_marks(); // save marks for all gens 376 // We want to discover references, but not process them yet. 377 // This mode is disabled in process_discovered_references if the 378 // generation does some collection work, or in 379 // enqueue_discovered_references if the generation returns 380 // without doing any work. 381 ReferenceProcessor* rp = gen->ref_processor(); 382 // If the discovery of ("weak") refs in this generation is 383 // atomic wrt other collectors in this configuration, we 384 // are guaranteed to have empty discovered ref lists. 385 if (rp->discovery_is_atomic()) { 386 rp->enable_discovery(); 387 rp->setup_policy(clear_soft_refs); 388 } else { 389 // collect() below will enable discovery as appropriate 390 } 391 gen->collect(full, clear_soft_refs, size, is_tlab); 392 if (!rp->enqueuing_is_done()) { 393 rp->enqueue_discovered_references(); 394 } else { 395 rp->set_enqueuing_is_done(false); 396 } 397 rp->verify_no_references_recorded(); 398 } 399 400 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 401 402 gen->stat_record()->accumulated_time.stop(); 403 404 update_gc_stats(gen, full); 405 406 if (run_verification && VerifyAfterGC) { 407 HandleMark hm; // Discard invalid handles created during verification 408 Universe::verify(" VerifyAfterGC:"); 409 } 410 411 if (PrintGCDetails) { 412 gclog_or_tty->print(":"); 413 gen->print_heap_change(prev_used); 414 } 415 } 416 417 void GenCollectedHeap::do_collection(bool full, 418 bool clear_all_soft_refs, 419 size_t size, 420 bool is_tlab, 421 GenerationType max_generation) { 422 ResourceMark rm; 423 DEBUG_ONLY(Thread* my_thread = Thread::current();) 424 425 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 426 assert(my_thread->is_VM_thread() || 427 my_thread->is_ConcurrentGC_thread(), 428 "incorrect thread type capability"); 429 assert(Heap_lock->is_locked(), 430 "the requesting thread should have the Heap_lock"); 431 guarantee(!is_gc_active(), "collection is not reentrant"); 432 433 if (GC_locker::check_active_before_gc()) { 434 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 435 } 436 437 const bool do_clear_all_soft_refs = clear_all_soft_refs || 438 collector_policy()->should_clear_all_soft_refs(); 439 440 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 441 442 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 443 444 print_heap_before_gc(); 445 446 { 447 FlagSetting fl(_is_gc_active, true); 448 449 bool complete = full && (max_generation == OldGen); 450 const char* gc_cause_prefix = complete ? "Full GC" : "GC"; 451 TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty); 452 // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later 453 // so we can assume here that the next GC id is what we want. 454 GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek()); 455 456 gc_prologue(complete); 457 increment_total_collections(complete); 458 459 size_t gch_prev_used = used(); 460 bool run_verification = total_collections() >= VerifyGCStartAt; 461 462 bool prepared_for_verification = false; 463 bool collected_old = false; 464 bool old_collects_young = complete && 465 _old_gen->full_collects_young_generation(); 466 if (!old_collects_young && 467 _young_gen->should_collect(full, size, is_tlab)) { 468 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 469 prepare_for_verify(); 470 prepared_for_verification = true; 471 } 472 473 assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking"); 474 collect_generation(_young_gen, 475 full, 476 size, 477 is_tlab, 478 run_verification && VerifyGCLevel <= 0, 479 do_clear_all_soft_refs, 480 false); 481 482 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 483 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 484 // Allocation request was met by young GC. 485 size = 0; 486 } 487 } 488 489 bool must_restore_marks_for_biased_locking = false; 490 491 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 492 if (!complete) { 493 // The full_collections increment was missed above. 494 increment_total_full_collections(); 495 } 496 497 pre_full_gc_dump(NULL); // do any pre full gc dumps 498 499 if (!prepared_for_verification && run_verification && 500 VerifyGCLevel <= 1 && VerifyBeforeGC) { 501 prepare_for_verify(); 502 } 503 504 assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking"); 505 collect_generation(_old_gen, 506 full, 507 size, 508 is_tlab, 509 run_verification && VerifyGCLevel <= 1, 510 do_clear_all_soft_refs, 511 true); 512 513 must_restore_marks_for_biased_locking = true; 514 collected_old = true; 515 } 516 517 // Update "complete" boolean wrt what actually transpired -- 518 // for instance, a promotion failure could have led to 519 // a whole heap collection. 520 complete = complete || collected_old; 521 522 if (complete) { // We did a full collection 523 // FIXME: See comment at pre_full_gc_dump call 524 post_full_gc_dump(NULL); // do any post full gc dumps 525 } 526 527 if (PrintGCDetails) { 528 print_heap_change(gch_prev_used); 529 530 // Print metaspace info for full GC with PrintGCDetails flag. 531 if (complete) { 532 MetaspaceAux::print_metaspace_change(metadata_prev_used); 533 } 534 } 535 536 // Adjust generation sizes. 537 if (collected_old) { 538 _old_gen->compute_new_size(); 539 } 540 _young_gen->compute_new_size(); 541 542 if (complete) { 543 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 544 ClassLoaderDataGraph::purge(); 545 MetaspaceAux::verify_metrics(); 546 // Resize the metaspace capacity after full collections 547 MetaspaceGC::compute_new_size(); 548 update_full_collections_completed(); 549 } 550 551 // Track memory usage and detect low memory after GC finishes 552 MemoryService::track_memory_usage(); 553 554 gc_epilogue(complete); 555 556 if (must_restore_marks_for_biased_locking) { 557 BiasedLocking::restore_marks(); 558 } 559 } 560 561 print_heap_after_gc(); 562 563 #ifdef TRACESPINNING 564 ParallelTaskTerminator::print_termination_counts(); 565 #endif 566 } 567 568 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 569 return collector_policy()->satisfy_failed_allocation(size, is_tlab); 570 } 571 572 #ifdef ASSERT 573 class AssertNonScavengableClosure: public OopClosure { 574 public: 575 virtual void do_oop(oop* p) { 576 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 577 "Referent should not be scavengable."); } 578 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 579 }; 580 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 581 #endif 582 583 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 584 ScanningOption so, 585 OopClosure* strong_roots, 586 OopClosure* weak_roots, 587 CLDClosure* strong_cld_closure, 588 CLDClosure* weak_cld_closure, 589 CodeBlobClosure* code_roots) { 590 // General roots. 591 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 592 assert(code_roots != NULL, "code root closure should always be set"); 593 // _n_termination for _process_strong_tasks should be set up stream 594 // in a method not running in a GC worker. Otherwise the GC worker 595 // could be trying to change the termination condition while the task 596 // is executing in another GC worker. 597 598 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 599 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 600 } 601 602 // Some CLDs contained in the thread frames should be considered strong. 603 // Don't process them if they will be processed during the ClassLoaderDataGraph phase. 604 CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL; 605 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 606 CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 607 608 bool is_par = scope->n_threads() > 1; 609 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p); 610 611 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 612 Universe::oops_do(strong_roots); 613 } 614 // Global (strong) JNI handles 615 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 616 JNIHandles::oops_do(strong_roots); 617 } 618 619 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 620 ObjectSynchronizer::oops_do(strong_roots); 621 } 622 if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) { 623 FlatProfiler::oops_do(strong_roots); 624 } 625 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 626 Management::oops_do(strong_roots); 627 } 628 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 629 JvmtiExport::oops_do(strong_roots); 630 } 631 632 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 633 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 634 } 635 636 // All threads execute the following. A specific chunk of buckets 637 // from the StringTable are the individual tasks. 638 if (weak_roots != NULL) { 639 if (is_par) { 640 StringTable::possibly_parallel_oops_do(weak_roots); 641 } else { 642 StringTable::oops_do(weak_roots); 643 } 644 } 645 646 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 647 if (so & SO_ScavengeCodeCache) { 648 assert(code_roots != NULL, "must supply closure for code cache"); 649 650 // We only visit parts of the CodeCache when scavenging. 651 CodeCache::scavenge_root_nmethods_do(code_roots); 652 } 653 if (so & SO_AllCodeCache) { 654 assert(code_roots != NULL, "must supply closure for code cache"); 655 656 // CMSCollector uses this to do intermediate-strength collections. 657 // We scan the entire code cache, since CodeCache::do_unloading is not called. 658 CodeCache::blobs_do(code_roots); 659 } 660 // Verify that the code cache contents are not subject to 661 // movement by a scavenging collection. 662 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 663 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 664 } 665 } 666 667 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope, 668 GenerationType type, 669 bool young_gen_as_roots, 670 ScanningOption so, 671 bool only_strong_roots, 672 OopsInGenClosure* not_older_gens, 673 OopsInGenClosure* older_gens, 674 CLDClosure* cld_closure) { 675 const bool is_adjust_phase = !only_strong_roots && !young_gen_as_roots; 676 677 bool is_moving_collection = false; 678 if (type == YoungGen || is_adjust_phase) { 679 // young collections are always moving 680 is_moving_collection = true; 681 } 682 683 MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection); 684 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens; 685 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 686 687 process_roots(scope, so, 688 not_older_gens, weak_roots, 689 cld_closure, weak_cld_closure, 690 &mark_code_closure); 691 692 if (young_gen_as_roots) { 693 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 694 if (type == OldGen) { 695 not_older_gens->set_generation(_young_gen); 696 _young_gen->oop_iterate(not_older_gens); 697 } 698 not_older_gens->reset_generation(); 699 } 700 } 701 // When collection is parallel, all threads get to cooperate to do 702 // old generation scanning. 703 if (type == YoungGen) { 704 older_gens->set_generation(_old_gen); 705 rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads()); 706 older_gens->reset_generation(); 707 } 708 709 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 710 } 711 712 713 class AlwaysTrueClosure: public BoolObjectClosure { 714 public: 715 bool do_object_b(oop p) { return true; } 716 }; 717 static AlwaysTrueClosure always_true; 718 719 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 720 JNIHandles::weak_oops_do(&always_true, root_closure); 721 _young_gen->ref_processor()->weak_oops_do(root_closure); 722 _old_gen->ref_processor()->weak_oops_do(root_closure); 723 } 724 725 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 726 void GenCollectedHeap:: \ 727 oop_since_save_marks_iterate(GenerationType gen, \ 728 OopClosureType* cur, \ 729 OopClosureType* older) { \ 730 if (gen == YoungGen) { \ 731 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 732 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 733 } else { \ 734 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 735 } \ 736 } 737 738 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 739 740 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 741 742 bool GenCollectedHeap::no_allocs_since_save_marks() { 743 return _young_gen->no_allocs_since_save_marks() && 744 _old_gen->no_allocs_since_save_marks(); 745 } 746 747 bool GenCollectedHeap::supports_inline_contig_alloc() const { 748 return _young_gen->supports_inline_contig_alloc(); 749 } 750 751 HeapWord** GenCollectedHeap::top_addr() const { 752 return _young_gen->top_addr(); 753 } 754 755 HeapWord** GenCollectedHeap::end_addr() const { 756 return _young_gen->end_addr(); 757 } 758 759 // public collection interfaces 760 761 void GenCollectedHeap::collect(GCCause::Cause cause) { 762 if (should_do_concurrent_full_gc(cause)) { 763 #if INCLUDE_ALL_GCS 764 // Mostly concurrent full collection. 765 collect_mostly_concurrent(cause); 766 #else // INCLUDE_ALL_GCS 767 ShouldNotReachHere(); 768 #endif // INCLUDE_ALL_GCS 769 } else if (cause == GCCause::_wb_young_gc) { 770 // Young collection for the WhiteBox API. 771 collect(cause, YoungGen); 772 } else { 773 #ifdef ASSERT 774 if (cause == GCCause::_scavenge_alot) { 775 // Young collection only. 776 collect(cause, YoungGen); 777 } else { 778 // Stop-the-world full collection. 779 collect(cause, OldGen); 780 } 781 #else 782 // Stop-the-world full collection. 783 collect(cause, OldGen); 784 #endif 785 } 786 } 787 788 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 789 // The caller doesn't have the Heap_lock 790 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 791 MutexLocker ml(Heap_lock); 792 collect_locked(cause, max_generation); 793 } 794 795 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 796 // The caller has the Heap_lock 797 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 798 collect_locked(cause, OldGen); 799 } 800 801 // this is the private collection interface 802 // The Heap_lock is expected to be held on entry. 803 804 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 805 // Read the GC count while holding the Heap_lock 806 unsigned int gc_count_before = total_collections(); 807 unsigned int full_gc_count_before = total_full_collections(); 808 { 809 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 810 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 811 cause, max_generation); 812 VMThread::execute(&op); 813 } 814 } 815 816 #if INCLUDE_ALL_GCS 817 bool GenCollectedHeap::create_cms_collector() { 818 819 assert(_old_gen->kind() == Generation::ConcurrentMarkSweep, 820 "Unexpected generation kinds"); 821 // Skip two header words in the block content verification 822 NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();) 823 assert(_gen_policy->is_concurrent_mark_sweep_policy(), "Unexpected policy type"); 824 CMSCollector* collector = 825 new CMSCollector((ConcurrentMarkSweepGeneration*)_old_gen, 826 _rem_set->as_CardTableRS(), 827 _gen_policy->as_concurrent_mark_sweep_policy()); 828 829 if (collector == NULL || !collector->completed_initialization()) { 830 if (collector) { 831 delete collector; // Be nice in embedded situation 832 } 833 vm_shutdown_during_initialization("Could not create CMS collector"); 834 return false; 835 } 836 return true; // success 837 } 838 839 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) { 840 assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock"); 841 842 MutexLocker ml(Heap_lock); 843 // Read the GC counts while holding the Heap_lock 844 unsigned int full_gc_count_before = total_full_collections(); 845 unsigned int gc_count_before = total_collections(); 846 { 847 MutexUnlocker mu(Heap_lock); 848 VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause); 849 VMThread::execute(&op); 850 } 851 } 852 #endif // INCLUDE_ALL_GCS 853 854 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 855 do_full_collection(clear_all_soft_refs, OldGen); 856 } 857 858 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 859 GenerationType last_generation) { 860 GenerationType local_last_generation; 861 if (!incremental_collection_will_fail(false /* don't consult_young */) && 862 gc_cause() == GCCause::_gc_locker) { 863 local_last_generation = YoungGen; 864 } else { 865 local_last_generation = last_generation; 866 } 867 868 do_collection(true, // full 869 clear_all_soft_refs, // clear_all_soft_refs 870 0, // size 871 false, // is_tlab 872 local_last_generation); // last_generation 873 // Hack XXX FIX ME !!! 874 // A scavenge may not have been attempted, or may have 875 // been attempted and failed, because the old gen was too full 876 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 877 incremental_collection_will_fail(false /* don't consult_young */)) { 878 if (PrintGCDetails) { 879 gclog_or_tty->print_cr("GC locker: Trying a full collection " 880 "because scavenge failed"); 881 } 882 // This time allow the old gen to be collected as well 883 do_collection(true, // full 884 clear_all_soft_refs, // clear_all_soft_refs 885 0, // size 886 false, // is_tlab 887 OldGen); // last_generation 888 } 889 } 890 891 bool GenCollectedHeap::is_in_young(oop p) { 892 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 893 assert(result == _young_gen->is_in_reserved(p), 894 err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p))); 895 return result; 896 } 897 898 // Returns "TRUE" iff "p" points into the committed areas of the heap. 899 bool GenCollectedHeap::is_in(const void* p) const { 900 return _young_gen->is_in(p) || _old_gen->is_in(p); 901 } 902 903 #ifdef ASSERT 904 // Don't implement this by using is_in_young(). This method is used 905 // in some cases to check that is_in_young() is correct. 906 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 907 assert(is_in_reserved(p) || p == NULL, 908 "Does not work if address is non-null and outside of the heap"); 909 return p < _young_gen->reserved().end() && p != NULL; 910 } 911 #endif 912 913 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 914 NoHeaderExtendedOopClosure no_header_cl(cl); 915 oop_iterate(&no_header_cl); 916 } 917 918 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 919 _young_gen->oop_iterate(cl); 920 _old_gen->oop_iterate(cl); 921 } 922 923 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 924 _young_gen->object_iterate(cl); 925 _old_gen->object_iterate(cl); 926 } 927 928 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 929 _young_gen->safe_object_iterate(cl); 930 _old_gen->safe_object_iterate(cl); 931 } 932 933 Space* GenCollectedHeap::space_containing(const void* addr) const { 934 Space* res = _young_gen->space_containing(addr); 935 if (res != NULL) { 936 return res; 937 } 938 res = _old_gen->space_containing(addr); 939 assert(res != NULL, "Could not find containing space"); 940 return res; 941 } 942 943 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 944 assert(is_in_reserved(addr), "block_start of address outside of heap"); 945 if (_young_gen->is_in_reserved(addr)) { 946 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 947 return _young_gen->block_start(addr); 948 } 949 950 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 951 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 952 return _old_gen->block_start(addr); 953 } 954 955 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 956 assert(is_in_reserved(addr), "block_size of address outside of heap"); 957 if (_young_gen->is_in_reserved(addr)) { 958 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 959 return _young_gen->block_size(addr); 960 } 961 962 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 963 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 964 return _old_gen->block_size(addr); 965 } 966 967 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 968 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 969 assert(block_start(addr) == addr, "addr must be a block start"); 970 if (_young_gen->is_in_reserved(addr)) { 971 return _young_gen->block_is_obj(addr); 972 } 973 974 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 975 return _old_gen->block_is_obj(addr); 976 } 977 978 bool GenCollectedHeap::supports_tlab_allocation() const { 979 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 980 return _young_gen->supports_tlab_allocation(); 981 } 982 983 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 984 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 985 if (_young_gen->supports_tlab_allocation()) { 986 return _young_gen->tlab_capacity(); 987 } 988 return 0; 989 } 990 991 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 992 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 993 if (_young_gen->supports_tlab_allocation()) { 994 return _young_gen->tlab_used(); 995 } 996 return 0; 997 } 998 999 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 1000 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1001 if (_young_gen->supports_tlab_allocation()) { 1002 return _young_gen->unsafe_max_tlab_alloc(); 1003 } 1004 return 0; 1005 } 1006 1007 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 1008 bool gc_overhead_limit_was_exceeded; 1009 return collector_policy()->mem_allocate_work(size /* size */, 1010 true /* is_tlab */, 1011 &gc_overhead_limit_was_exceeded); 1012 } 1013 1014 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1015 // from the list headed by "*prev_ptr". 1016 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1017 bool first = true; 1018 size_t min_size = 0; // "first" makes this conceptually infinite. 1019 ScratchBlock **smallest_ptr, *smallest; 1020 ScratchBlock *cur = *prev_ptr; 1021 while (cur) { 1022 assert(*prev_ptr == cur, "just checking"); 1023 if (first || cur->num_words < min_size) { 1024 smallest_ptr = prev_ptr; 1025 smallest = cur; 1026 min_size = smallest->num_words; 1027 first = false; 1028 } 1029 prev_ptr = &cur->next; 1030 cur = cur->next; 1031 } 1032 smallest = *smallest_ptr; 1033 *smallest_ptr = smallest->next; 1034 return smallest; 1035 } 1036 1037 // Sort the scratch block list headed by res into decreasing size order, 1038 // and set "res" to the result. 1039 static void sort_scratch_list(ScratchBlock*& list) { 1040 ScratchBlock* sorted = NULL; 1041 ScratchBlock* unsorted = list; 1042 while (unsorted) { 1043 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1044 smallest->next = sorted; 1045 sorted = smallest; 1046 } 1047 list = sorted; 1048 } 1049 1050 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1051 size_t max_alloc_words) { 1052 ScratchBlock* res = NULL; 1053 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1054 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1055 sort_scratch_list(res); 1056 return res; 1057 } 1058 1059 void GenCollectedHeap::release_scratch() { 1060 _young_gen->reset_scratch(); 1061 _old_gen->reset_scratch(); 1062 } 1063 1064 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1065 void do_generation(Generation* gen) { 1066 gen->prepare_for_verify(); 1067 } 1068 }; 1069 1070 void GenCollectedHeap::prepare_for_verify() { 1071 ensure_parsability(false); // no need to retire TLABs 1072 GenPrepareForVerifyClosure blk; 1073 generation_iterate(&blk, false); 1074 } 1075 1076 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1077 bool old_to_young) { 1078 if (old_to_young) { 1079 cl->do_generation(_old_gen); 1080 cl->do_generation(_young_gen); 1081 } else { 1082 cl->do_generation(_young_gen); 1083 cl->do_generation(_old_gen); 1084 } 1085 } 1086 1087 bool GenCollectedHeap::is_maximal_no_gc() const { 1088 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1089 } 1090 1091 void GenCollectedHeap::save_marks() { 1092 _young_gen->save_marks(); 1093 _old_gen->save_marks(); 1094 } 1095 1096 GenCollectedHeap* GenCollectedHeap::heap() { 1097 CollectedHeap* heap = Universe::heap(); 1098 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1099 assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap"); 1100 return (GenCollectedHeap*)heap; 1101 } 1102 1103 void GenCollectedHeap::prepare_for_compaction() { 1104 // Start by compacting into same gen. 1105 CompactPoint cp(_old_gen); 1106 _old_gen->prepare_for_compaction(&cp); 1107 _young_gen->prepare_for_compaction(&cp); 1108 } 1109 1110 GCStats* GenCollectedHeap::gc_stats(Generation* gen) const { 1111 return gen->gc_stats(); 1112 } 1113 1114 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) { 1115 if (!silent) { 1116 gclog_or_tty->print("%s", _old_gen->name()); 1117 gclog_or_tty->print(" "); 1118 } 1119 _old_gen->verify(); 1120 1121 if (!silent) { 1122 gclog_or_tty->print("%s", _young_gen->name()); 1123 gclog_or_tty->print(" "); 1124 } 1125 _young_gen->verify(); 1126 1127 if (!silent) { 1128 gclog_or_tty->print("remset "); 1129 } 1130 rem_set()->verify(); 1131 } 1132 1133 void GenCollectedHeap::print_on(outputStream* st) const { 1134 _young_gen->print_on(st); 1135 _old_gen->print_on(st); 1136 MetaspaceAux::print_on(st); 1137 } 1138 1139 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1140 if (workers() != NULL) { 1141 workers()->threads_do(tc); 1142 } 1143 #if INCLUDE_ALL_GCS 1144 if (UseConcMarkSweepGC) { 1145 ConcurrentMarkSweepThread::threads_do(tc); 1146 } 1147 #endif // INCLUDE_ALL_GCS 1148 } 1149 1150 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1151 #if INCLUDE_ALL_GCS 1152 if (UseConcMarkSweepGC) { 1153 workers()->print_worker_threads_on(st); 1154 ConcurrentMarkSweepThread::print_all_on(st); 1155 } 1156 #endif // INCLUDE_ALL_GCS 1157 } 1158 1159 void GenCollectedHeap::print_on_error(outputStream* st) const { 1160 this->CollectedHeap::print_on_error(st); 1161 1162 #if INCLUDE_ALL_GCS 1163 if (UseConcMarkSweepGC) { 1164 st->cr(); 1165 CMSCollector::print_on_error(st); 1166 } 1167 #endif // INCLUDE_ALL_GCS 1168 } 1169 1170 void GenCollectedHeap::print_tracing_info() const { 1171 if (TraceYoungGenTime) { 1172 _young_gen->print_summary_info(); 1173 } 1174 if (TraceOldGenTime) { 1175 _old_gen->print_summary_info(); 1176 } 1177 } 1178 1179 void GenCollectedHeap::print_heap_change(size_t prev_used) const { 1180 if (PrintGCDetails && Verbose) { 1181 gclog_or_tty->print(" " SIZE_FORMAT 1182 "->" SIZE_FORMAT 1183 "(" SIZE_FORMAT ")", 1184 prev_used, used(), capacity()); 1185 } else { 1186 gclog_or_tty->print(" " SIZE_FORMAT "K" 1187 "->" SIZE_FORMAT "K" 1188 "(" SIZE_FORMAT "K)", 1189 prev_used / K, used() / K, capacity() / K); 1190 } 1191 } 1192 1193 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1194 private: 1195 bool _full; 1196 public: 1197 void do_generation(Generation* gen) { 1198 gen->gc_prologue(_full); 1199 } 1200 GenGCPrologueClosure(bool full) : _full(full) {}; 1201 }; 1202 1203 void GenCollectedHeap::gc_prologue(bool full) { 1204 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1205 1206 always_do_update_barrier = false; 1207 // Fill TLAB's and such 1208 CollectedHeap::accumulate_statistics_all_tlabs(); 1209 ensure_parsability(true); // retire TLABs 1210 1211 // Walk generations 1212 GenGCPrologueClosure blk(full); 1213 generation_iterate(&blk, false); // not old-to-young. 1214 }; 1215 1216 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1217 private: 1218 bool _full; 1219 public: 1220 void do_generation(Generation* gen) { 1221 gen->gc_epilogue(_full); 1222 } 1223 GenGCEpilogueClosure(bool full) : _full(full) {}; 1224 }; 1225 1226 void GenCollectedHeap::gc_epilogue(bool full) { 1227 #ifdef COMPILER2 1228 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1229 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1230 guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1231 #endif /* COMPILER2 */ 1232 1233 resize_all_tlabs(); 1234 1235 GenGCEpilogueClosure blk(full); 1236 generation_iterate(&blk, false); // not old-to-young. 1237 1238 if (!CleanChunkPoolAsync) { 1239 Chunk::clean_chunk_pool(); 1240 } 1241 1242 MetaspaceCounters::update_performance_counters(); 1243 CompressedClassSpaceCounters::update_performance_counters(); 1244 1245 always_do_update_barrier = UseConcMarkSweepGC; 1246 }; 1247 1248 #ifndef PRODUCT 1249 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1250 private: 1251 public: 1252 void do_generation(Generation* gen) { 1253 gen->record_spaces_top(); 1254 } 1255 }; 1256 1257 void GenCollectedHeap::record_gen_tops_before_GC() { 1258 if (ZapUnusedHeapArea) { 1259 GenGCSaveTopsBeforeGCClosure blk; 1260 generation_iterate(&blk, false); // not old-to-young. 1261 } 1262 } 1263 #endif // not PRODUCT 1264 1265 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1266 public: 1267 void do_generation(Generation* gen) { 1268 gen->ensure_parsability(); 1269 } 1270 }; 1271 1272 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1273 CollectedHeap::ensure_parsability(retire_tlabs); 1274 GenEnsureParsabilityClosure ep_cl; 1275 generation_iterate(&ep_cl, false); 1276 } 1277 1278 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1279 oop obj, 1280 size_t obj_size) { 1281 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1282 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1283 HeapWord* result = NULL; 1284 1285 result = old_gen->expand_and_allocate(obj_size, false); 1286 1287 if (result != NULL) { 1288 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1289 } 1290 return oop(result); 1291 } 1292 1293 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1294 jlong _time; // in ms 1295 jlong _now; // in ms 1296 1297 public: 1298 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1299 1300 jlong time() { return _time; } 1301 1302 void do_generation(Generation* gen) { 1303 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1304 } 1305 }; 1306 1307 jlong GenCollectedHeap::millis_since_last_gc() { 1308 // We need a monotonically non-decreasing time in ms but 1309 // os::javaTimeMillis() does not guarantee monotonicity. 1310 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1311 GenTimeOfLastGCClosure tolgc_cl(now); 1312 // iterate over generations getting the oldest 1313 // time that a generation was collected 1314 generation_iterate(&tolgc_cl, false); 1315 1316 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1317 // provided the underlying platform provides such a time source 1318 // (and it is bug free). So we still have to guard against getting 1319 // back a time later than 'now'. 1320 jlong retVal = now - tolgc_cl.time(); 1321 if (retVal < 0) { 1322 NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);) 1323 return 0; 1324 } 1325 return retVal; 1326 }