1 /* 2 * Copyright (c) 2000, 2017, 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 "aot/aotLoader.hpp" 27 #include "classfile/symbolTable.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/icBuffer.hpp" 33 #include "gc/shared/collectedHeap.inline.hpp" 34 #include "gc/shared/collectorCounters.hpp" 35 #include "gc/shared/gcId.hpp" 36 #include "gc/shared/gcLocker.inline.hpp" 37 #include "gc/shared/gcTrace.hpp" 38 #include "gc/shared/gcTraceTime.inline.hpp" 39 #include "gc/shared/genCollectedHeap.hpp" 40 #include "gc/shared/genOopClosures.inline.hpp" 41 #include "gc/shared/generationSpec.hpp" 42 #include "gc/shared/space.hpp" 43 #include "gc/shared/strongRootsScope.hpp" 44 #include "gc/shared/vmGCOperations.hpp" 45 #include "gc/shared/weakProcessor.hpp" 46 #include "gc/shared/workgroup.hpp" 47 #include "memory/filemap.hpp" 48 #include "memory/resourceArea.hpp" 49 #include "oops/oop.inline.hpp" 50 #include "runtime/biasedLocking.hpp" 51 #include "runtime/handles.hpp" 52 #include "runtime/handles.inline.hpp" 53 #include "runtime/java.hpp" 54 #include "runtime/vmThread.hpp" 55 #include "services/management.hpp" 56 #include "services/memoryService.hpp" 57 #include "utilities/debug.hpp" 58 #include "utilities/formatBuffer.hpp" 59 #include "utilities/macros.hpp" 60 #include "utilities/stack.inline.hpp" 61 #include "utilities/vmError.hpp" 62 63 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) : 64 CollectedHeap(), 65 _rem_set(NULL), 66 _gen_policy(policy), 67 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)), 68 _full_collections_completed(0) 69 { 70 assert(policy != NULL, "Sanity check"); 71 } 72 73 jint GenCollectedHeap::initialize() { 74 CollectedHeap::pre_initialize(); 75 76 // While there are no constraints in the GC code that HeapWordSize 77 // be any particular value, there are multiple other areas in the 78 // system which believe this to be true (e.g. oop->object_size in some 79 // cases incorrectly returns the size in wordSize units rather than 80 // HeapWordSize). 81 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 82 83 // Allocate space for the heap. 84 85 char* heap_address; 86 ReservedSpace heap_rs; 87 88 size_t heap_alignment = collector_policy()->heap_alignment(); 89 90 heap_address = allocate(heap_alignment, &heap_rs); 91 92 if (!heap_rs.is_reserved()) { 93 vm_shutdown_during_initialization( 94 "Could not reserve enough space for object heap"); 95 return JNI_ENOMEM; 96 } 97 98 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 99 100 _rem_set = collector_policy()->create_rem_set(reserved_region()); 101 set_barrier_set(rem_set()->bs()); 102 103 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false); 104 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set()); 105 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size()); 106 107 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false); 108 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set()); 109 clear_incremental_collection_failed(); 110 111 return JNI_OK; 112 } 113 114 char* GenCollectedHeap::allocate(size_t alignment, 115 ReservedSpace* heap_rs){ 116 // Now figure out the total size. 117 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 118 assert(alignment % pageSize == 0, "Must be"); 119 120 GenerationSpec* young_spec = gen_policy()->young_gen_spec(); 121 GenerationSpec* old_spec = gen_policy()->old_gen_spec(); 122 123 // Check for overflow. 124 size_t total_reserved = young_spec->max_size() + old_spec->max_size(); 125 if (total_reserved < young_spec->max_size()) { 126 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 127 "the maximum representable size"); 128 } 129 assert(total_reserved % alignment == 0, 130 "Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 131 SIZE_FORMAT, total_reserved, alignment); 132 133 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 134 135 os::trace_page_sizes("Heap", 136 collector_policy()->min_heap_byte_size(), 137 total_reserved, 138 alignment, 139 heap_rs->base(), 140 heap_rs->size()); 141 142 return heap_rs->base(); 143 } 144 145 void GenCollectedHeap::post_initialize() { 146 ref_processing_init(); 147 check_gen_kinds(); 148 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 149 150 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(), 151 _old_gen->capacity(), 152 def_new_gen->from()->capacity()); 153 _gen_policy->initialize_gc_policy_counters(); 154 } 155 156 void GenCollectedHeap::check_gen_kinds() { 157 assert(young_gen()->kind() == Generation::DefNew, 158 "Wrong youngest generation type"); 159 assert(old_gen()->kind() == Generation::MarkSweepCompact, 160 "Wrong generation kind"); 161 } 162 163 void GenCollectedHeap::ref_processing_init() { 164 _young_gen->ref_processor_init(); 165 _old_gen->ref_processor_init(); 166 } 167 168 size_t GenCollectedHeap::capacity() const { 169 return _young_gen->capacity() + _old_gen->capacity(); 170 } 171 172 size_t GenCollectedHeap::used() const { 173 return _young_gen->used() + _old_gen->used(); 174 } 175 176 void GenCollectedHeap::save_used_regions() { 177 _old_gen->save_used_region(); 178 _young_gen->save_used_region(); 179 } 180 181 size_t GenCollectedHeap::max_capacity() const { 182 return _young_gen->max_capacity() + _old_gen->max_capacity(); 183 } 184 185 // Update the _full_collections_completed counter 186 // at the end of a stop-world full GC. 187 unsigned int GenCollectedHeap::update_full_collections_completed() { 188 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 189 assert(_full_collections_completed <= _total_full_collections, 190 "Can't complete more collections than were started"); 191 _full_collections_completed = _total_full_collections; 192 ml.notify_all(); 193 return _full_collections_completed; 194 } 195 196 // Update the _full_collections_completed counter, as appropriate, 197 // at the end of a concurrent GC cycle. Note the conditional update 198 // below to allow this method to be called by a concurrent collector 199 // without synchronizing in any manner with the VM thread (which 200 // may already have initiated a STW full collection "concurrently"). 201 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 202 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 203 assert((_full_collections_completed <= _total_full_collections) && 204 (count <= _total_full_collections), 205 "Can't complete more collections than were started"); 206 if (count > _full_collections_completed) { 207 _full_collections_completed = count; 208 ml.notify_all(); 209 } 210 return _full_collections_completed; 211 } 212 213 214 #ifndef PRODUCT 215 // Override of memory state checking method in CollectedHeap: 216 // Some collectors (CMS for example) can't have badHeapWordVal written 217 // in the first two words of an object. (For instance , in the case of 218 // CMS these words hold state used to synchronize between certain 219 // (concurrent) GC steps and direct allocating mutators.) 220 // The skip_header_HeapWords() method below, allows us to skip 221 // over the requisite number of HeapWord's. Note that (for 222 // generational collectors) this means that those many words are 223 // skipped in each object, irrespective of the generation in which 224 // that object lives. The resultant loss of precision seems to be 225 // harmless and the pain of avoiding that imprecision appears somewhat 226 // higher than we are prepared to pay for such rudimentary debugging 227 // support. 228 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 229 size_t size) { 230 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 231 // We are asked to check a size in HeapWords, 232 // but the memory is mangled in juint words. 233 juint* start = (juint*) (addr + skip_header_HeapWords()); 234 juint* end = (juint*) (addr + size); 235 for (juint* slot = start; slot < end; slot += 1) { 236 assert(*slot == badHeapWordVal, 237 "Found non badHeapWordValue in pre-allocation check"); 238 } 239 } 240 } 241 #endif 242 243 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 244 bool is_tlab, 245 bool first_only) { 246 HeapWord* res = NULL; 247 248 if (_young_gen->should_allocate(size, is_tlab)) { 249 res = _young_gen->allocate(size, is_tlab); 250 if (res != NULL || first_only) { 251 return res; 252 } 253 } 254 255 if (_old_gen->should_allocate(size, is_tlab)) { 256 res = _old_gen->allocate(size, is_tlab); 257 } 258 259 return res; 260 } 261 262 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 263 bool* gc_overhead_limit_was_exceeded) { 264 return gen_policy()->mem_allocate_work(size, 265 false /* is_tlab */, 266 gc_overhead_limit_was_exceeded); 267 } 268 269 bool GenCollectedHeap::must_clear_all_soft_refs() { 270 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || 271 _gc_cause == GCCause::_wb_full_gc; 272 } 273 274 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 275 bool is_tlab, bool run_verification, bool clear_soft_refs, 276 bool restore_marks_for_biased_locking) { 277 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 278 GCTraceTime(Trace, gc, phases) t1(title); 279 TraceCollectorStats tcs(gen->counters()); 280 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 281 282 gen->stat_record()->invocations++; 283 gen->stat_record()->accumulated_time.start(); 284 285 // Must be done anew before each collection because 286 // a previous collection will do mangling and will 287 // change top of some spaces. 288 record_gen_tops_before_GC(); 289 290 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 291 292 if (run_verification && VerifyBeforeGC) { 293 HandleMark hm; // Discard invalid handles created during verification 294 Universe::verify("Before GC"); 295 } 296 COMPILER2_PRESENT(DerivedPointerTable::clear()); 297 298 if (restore_marks_for_biased_locking) { 299 // We perform this mark word preservation work lazily 300 // because it's only at this point that we know whether we 301 // absolutely have to do it; we want to avoid doing it for 302 // scavenge-only collections where it's unnecessary 303 BiasedLocking::preserve_marks(); 304 } 305 306 // Do collection work 307 { 308 // Note on ref discovery: For what appear to be historical reasons, 309 // GCH enables and disabled (by enqueing) refs discovery. 310 // In the future this should be moved into the generation's 311 // collect method so that ref discovery and enqueueing concerns 312 // are local to a generation. The collect method could return 313 // an appropriate indication in the case that notification on 314 // the ref lock was needed. This will make the treatment of 315 // weak refs more uniform (and indeed remove such concerns 316 // from GCH). XXX 317 318 HandleMark hm; // Discard invalid handles created during gc 319 save_marks(); // save marks for all gens 320 // We want to discover references, but not process them yet. 321 // This mode is disabled in process_discovered_references if the 322 // generation does some collection work, or in 323 // enqueue_discovered_references if the generation returns 324 // without doing any work. 325 ReferenceProcessor* rp = gen->ref_processor(); 326 // If the discovery of ("weak") refs in this generation is 327 // atomic wrt other collectors in this configuration, we 328 // are guaranteed to have empty discovered ref lists. 329 if (rp->discovery_is_atomic()) { 330 rp->enable_discovery(); 331 rp->setup_policy(clear_soft_refs); 332 } else { 333 // collect() below will enable discovery as appropriate 334 } 335 gen->collect(full, clear_soft_refs, size, is_tlab); 336 if (!rp->enqueuing_is_done()) { 337 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q()); 338 rp->enqueue_discovered_references(NULL, &pt); 339 pt.print_enqueue_phase(); 340 } else { 341 rp->set_enqueuing_is_done(false); 342 } 343 rp->verify_no_references_recorded(); 344 } 345 346 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 347 348 gen->stat_record()->accumulated_time.stop(); 349 350 update_gc_stats(gen, full); 351 352 if (run_verification && VerifyAfterGC) { 353 HandleMark hm; // Discard invalid handles created during verification 354 Universe::verify("After GC"); 355 } 356 } 357 358 void GenCollectedHeap::do_collection(bool full, 359 bool clear_all_soft_refs, 360 size_t size, 361 bool is_tlab, 362 GenerationType max_generation) { 363 ResourceMark rm; 364 DEBUG_ONLY(Thread* my_thread = Thread::current();) 365 366 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 367 assert(my_thread->is_VM_thread() || 368 my_thread->is_ConcurrentGC_thread(), 369 "incorrect thread type capability"); 370 assert(Heap_lock->is_locked(), 371 "the requesting thread should have the Heap_lock"); 372 guarantee(!is_gc_active(), "collection is not reentrant"); 373 374 if (GCLocker::check_active_before_gc()) { 375 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 376 } 377 378 GCIdMarkAndRestore gc_id_mark; 379 380 const bool do_clear_all_soft_refs = clear_all_soft_refs || 381 collector_policy()->should_clear_all_soft_refs(); 382 383 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 384 385 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 386 387 print_heap_before_gc(); 388 389 { 390 FlagSetting fl(_is_gc_active, true); 391 392 bool complete = full && (max_generation == OldGen); 393 bool old_collects_young = complete && !ScavengeBeforeFullGC; 394 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 395 396 FormatBuffer<> gc_string("%s", "Pause "); 397 if (do_young_collection) { 398 gc_string.append("Young"); 399 } else { 400 gc_string.append("Full"); 401 } 402 403 GCTraceCPUTime tcpu; 404 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true); 405 406 gc_prologue(complete); 407 increment_total_collections(complete); 408 409 size_t young_prev_used = _young_gen->used(); 410 size_t old_prev_used = _old_gen->used(); 411 412 bool run_verification = total_collections() >= VerifyGCStartAt; 413 414 bool prepared_for_verification = false; 415 bool collected_old = false; 416 417 if (do_young_collection) { 418 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 419 prepare_for_verify(); 420 prepared_for_verification = true; 421 } 422 423 collect_generation(_young_gen, 424 full, 425 size, 426 is_tlab, 427 run_verification && VerifyGCLevel <= 0, 428 do_clear_all_soft_refs, 429 false); 430 431 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 432 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 433 // Allocation request was met by young GC. 434 size = 0; 435 } 436 } 437 438 bool must_restore_marks_for_biased_locking = false; 439 440 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 441 if (!complete) { 442 // The full_collections increment was missed above. 443 increment_total_full_collections(); 444 } 445 446 if (!prepared_for_verification && run_verification && 447 VerifyGCLevel <= 1 && VerifyBeforeGC) { 448 prepare_for_verify(); 449 } 450 451 if (do_young_collection) { 452 // We did a young GC. Need a new GC id for the old GC. 453 GCIdMarkAndRestore gc_id_mark; 454 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 455 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 456 } else { 457 // No young GC done. Use the same GC id as was set up earlier in this method. 458 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 459 } 460 461 must_restore_marks_for_biased_locking = true; 462 collected_old = true; 463 } 464 465 // Update "complete" boolean wrt what actually transpired -- 466 // for instance, a promotion failure could have led to 467 // a whole heap collection. 468 complete = complete || collected_old; 469 470 print_heap_change(young_prev_used, old_prev_used); 471 MetaspaceAux::print_metaspace_change(metadata_prev_used); 472 473 // Adjust generation sizes. 474 if (collected_old) { 475 _old_gen->compute_new_size(); 476 } 477 _young_gen->compute_new_size(); 478 479 if (complete) { 480 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 481 ClassLoaderDataGraph::purge(); 482 MetaspaceAux::verify_metrics(); 483 // Resize the metaspace capacity after full collections 484 MetaspaceGC::compute_new_size(); 485 update_full_collections_completed(); 486 } 487 488 // Track memory usage and detect low memory after GC finishes 489 MemoryService::track_memory_usage(); 490 491 gc_epilogue(complete); 492 493 if (must_restore_marks_for_biased_locking) { 494 BiasedLocking::restore_marks(); 495 } 496 } 497 498 print_heap_after_gc(); 499 500 #ifdef TRACESPINNING 501 ParallelTaskTerminator::print_termination_counts(); 502 #endif 503 } 504 505 void GenCollectedHeap::register_nmethod(nmethod* nm) { 506 CodeCache::register_scavenge_root_nmethod(nm); 507 } 508 509 void GenCollectedHeap::verify_nmethod(nmethod* nm) { 510 CodeCache::verify_scavenge_root_nmethod(nm); 511 } 512 513 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 514 return gen_policy()->satisfy_failed_allocation(size, is_tlab); 515 } 516 517 #ifdef ASSERT 518 class AssertNonScavengableClosure: public OopClosure { 519 public: 520 virtual void do_oop(oop* p) { 521 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 522 "Referent should not be scavengable."); } 523 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 524 }; 525 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 526 #endif 527 528 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 529 ScanningOption so, 530 OopClosure* strong_roots, 531 OopClosure* weak_roots, 532 CLDClosure* strong_cld_closure, 533 CLDClosure* weak_cld_closure, 534 CodeBlobToOopClosure* code_roots) { 535 // General roots. 536 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 537 assert(code_roots != NULL, "code root closure should always be set"); 538 // _n_termination for _process_strong_tasks should be set up stream 539 // in a method not running in a GC worker. Otherwise the GC worker 540 // could be trying to change the termination condition while the task 541 // is executing in another GC worker. 542 543 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 544 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 545 } 546 547 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 548 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 549 550 bool is_par = scope->n_threads() > 1; 551 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p); 552 553 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 554 Universe::oops_do(strong_roots); 555 } 556 // Global (strong) JNI handles 557 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 558 JNIHandles::oops_do(strong_roots); 559 } 560 561 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 562 ObjectSynchronizer::oops_do(strong_roots); 563 } 564 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 565 Management::oops_do(strong_roots); 566 } 567 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 568 JvmtiExport::oops_do(strong_roots); 569 } 570 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) { 571 AOTLoader::oops_do(strong_roots); 572 } 573 574 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 575 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 576 } 577 578 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 579 if (so & SO_ScavengeCodeCache) { 580 assert(code_roots != NULL, "must supply closure for code cache"); 581 582 // We only visit parts of the CodeCache when scavenging. 583 CodeCache::scavenge_root_nmethods_do(code_roots); 584 } 585 if (so & SO_AllCodeCache) { 586 assert(code_roots != NULL, "must supply closure for code cache"); 587 588 // CMSCollector uses this to do intermediate-strength collections. 589 // We scan the entire code cache, since CodeCache::do_unloading is not called. 590 CodeCache::blobs_do(code_roots); 591 } 592 // Verify that the code cache contents are not subject to 593 // movement by a scavenging collection. 594 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 595 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 596 } 597 } 598 599 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope, 600 OopClosure* root_closure) { 601 assert(root_closure != NULL, "Must be set"); 602 // All threads execute the following. A specific chunk of buckets 603 // from the StringTable are the individual tasks. 604 if (scope->n_threads() > 1) { 605 StringTable::possibly_parallel_oops_do(root_closure); 606 } else { 607 StringTable::oops_do(root_closure); 608 } 609 } 610 611 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope, 612 OopsInGenClosure* root_closure, 613 OopsInGenClosure* old_gen_closure, 614 CLDClosure* cld_closure) { 615 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations); 616 617 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure, 618 cld_closure, cld_closure, &mark_code_closure); 619 process_string_table_roots(scope, root_closure); 620 621 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 622 root_closure->reset_generation(); 623 } 624 625 // When collection is parallel, all threads get to cooperate to do 626 // old generation scanning. 627 old_gen_closure->set_generation(_old_gen); 628 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); 629 old_gen_closure->reset_generation(); 630 631 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 632 } 633 634 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope, 635 bool is_adjust_phase, 636 ScanningOption so, 637 bool only_strong_roots, 638 OopsInGenClosure* root_closure, 639 CLDClosure* cld_closure) { 640 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase); 641 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure; 642 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 643 644 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure); 645 if (is_adjust_phase) { 646 // We never treat the string table as roots during marking 647 // for the full gc, so we only need to process it during 648 // the adjust phase. 649 process_string_table_roots(scope, root_closure); 650 } 651 652 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 653 } 654 655 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 656 WeakProcessor::oops_do(root_closure); 657 _young_gen->ref_processor()->weak_oops_do(root_closure); 658 _old_gen->ref_processor()->weak_oops_do(root_closure); 659 } 660 661 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 662 void GenCollectedHeap:: \ 663 oop_since_save_marks_iterate(GenerationType gen, \ 664 OopClosureType* cur, \ 665 OopClosureType* older) { \ 666 if (gen == YoungGen) { \ 667 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 668 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 669 } else { \ 670 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 671 } \ 672 } 673 674 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 675 676 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 677 678 bool GenCollectedHeap::no_allocs_since_save_marks() { 679 return _young_gen->no_allocs_since_save_marks() && 680 _old_gen->no_allocs_since_save_marks(); 681 } 682 683 bool GenCollectedHeap::supports_inline_contig_alloc() const { 684 return _young_gen->supports_inline_contig_alloc(); 685 } 686 687 HeapWord* volatile* GenCollectedHeap::top_addr() const { 688 return _young_gen->top_addr(); 689 } 690 691 HeapWord** GenCollectedHeap::end_addr() const { 692 return _young_gen->end_addr(); 693 } 694 695 // public collection interfaces 696 697 void GenCollectedHeap::collect(GCCause::Cause cause) { 698 if (cause == GCCause::_wb_young_gc) { 699 // Young collection for the WhiteBox API. 700 collect(cause, YoungGen); 701 } else { 702 #ifdef ASSERT 703 if (cause == GCCause::_scavenge_alot) { 704 // Young collection only. 705 collect(cause, YoungGen); 706 } else { 707 // Stop-the-world full collection. 708 collect(cause, OldGen); 709 } 710 #else 711 // Stop-the-world full collection. 712 collect(cause, OldGen); 713 #endif 714 } 715 } 716 717 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 718 // The caller doesn't have the Heap_lock 719 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 720 MutexLocker ml(Heap_lock); 721 collect_locked(cause, max_generation); 722 } 723 724 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 725 // The caller has the Heap_lock 726 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 727 collect_locked(cause, OldGen); 728 } 729 730 // this is the private collection interface 731 // The Heap_lock is expected to be held on entry. 732 733 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 734 // Read the GC count while holding the Heap_lock 735 unsigned int gc_count_before = total_collections(); 736 unsigned int full_gc_count_before = total_full_collections(); 737 { 738 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 739 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 740 cause, max_generation); 741 VMThread::execute(&op); 742 } 743 } 744 745 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 746 do_full_collection(clear_all_soft_refs, OldGen); 747 } 748 749 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 750 GenerationType last_generation) { 751 GenerationType local_last_generation; 752 if (!incremental_collection_will_fail(false /* don't consult_young */) && 753 gc_cause() == GCCause::_gc_locker) { 754 local_last_generation = YoungGen; 755 } else { 756 local_last_generation = last_generation; 757 } 758 759 do_collection(true, // full 760 clear_all_soft_refs, // clear_all_soft_refs 761 0, // size 762 false, // is_tlab 763 local_last_generation); // last_generation 764 // Hack XXX FIX ME !!! 765 // A scavenge may not have been attempted, or may have 766 // been attempted and failed, because the old gen was too full 767 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 768 incremental_collection_will_fail(false /* don't consult_young */)) { 769 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 770 // This time allow the old gen to be collected as well 771 do_collection(true, // full 772 clear_all_soft_refs, // clear_all_soft_refs 773 0, // size 774 false, // is_tlab 775 OldGen); // last_generation 776 } 777 } 778 779 bool GenCollectedHeap::is_in_young(oop p) { 780 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 781 assert(result == _young_gen->is_in_reserved(p), 782 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 783 return result; 784 } 785 786 // Returns "TRUE" iff "p" points into the committed areas of the heap. 787 bool GenCollectedHeap::is_in(const void* p) const { 788 return _young_gen->is_in(p) || _old_gen->is_in(p); 789 } 790 791 #ifdef ASSERT 792 // Don't implement this by using is_in_young(). This method is used 793 // in some cases to check that is_in_young() is correct. 794 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 795 assert(is_in_reserved(p) || p == NULL, 796 "Does not work if address is non-null and outside of the heap"); 797 return p < _young_gen->reserved().end() && p != NULL; 798 } 799 #endif 800 801 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 802 NoHeaderExtendedOopClosure no_header_cl(cl); 803 oop_iterate(&no_header_cl); 804 } 805 806 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 807 _young_gen->oop_iterate(cl); 808 _old_gen->oop_iterate(cl); 809 } 810 811 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 812 _young_gen->object_iterate(cl); 813 _old_gen->object_iterate(cl); 814 } 815 816 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 817 _young_gen->safe_object_iterate(cl); 818 _old_gen->safe_object_iterate(cl); 819 } 820 821 Space* GenCollectedHeap::space_containing(const void* addr) const { 822 Space* res = _young_gen->space_containing(addr); 823 if (res != NULL) { 824 return res; 825 } 826 res = _old_gen->space_containing(addr); 827 assert(res != NULL, "Could not find containing space"); 828 return res; 829 } 830 831 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 832 assert(is_in_reserved(addr), "block_start of address outside of heap"); 833 if (_young_gen->is_in_reserved(addr)) { 834 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 835 return _young_gen->block_start(addr); 836 } 837 838 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 839 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 840 return _old_gen->block_start(addr); 841 } 842 843 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 844 assert(is_in_reserved(addr), "block_size of address outside of heap"); 845 if (_young_gen->is_in_reserved(addr)) { 846 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 847 return _young_gen->block_size(addr); 848 } 849 850 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 851 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 852 return _old_gen->block_size(addr); 853 } 854 855 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 856 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 857 assert(block_start(addr) == addr, "addr must be a block start"); 858 if (_young_gen->is_in_reserved(addr)) { 859 return _young_gen->block_is_obj(addr); 860 } 861 862 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 863 return _old_gen->block_is_obj(addr); 864 } 865 866 bool GenCollectedHeap::supports_tlab_allocation() const { 867 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 868 return _young_gen->supports_tlab_allocation(); 869 } 870 871 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 872 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 873 if (_young_gen->supports_tlab_allocation()) { 874 return _young_gen->tlab_capacity(); 875 } 876 return 0; 877 } 878 879 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 880 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 881 if (_young_gen->supports_tlab_allocation()) { 882 return _young_gen->tlab_used(); 883 } 884 return 0; 885 } 886 887 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 888 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 889 if (_young_gen->supports_tlab_allocation()) { 890 return _young_gen->unsafe_max_tlab_alloc(); 891 } 892 return 0; 893 } 894 895 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 896 bool gc_overhead_limit_was_exceeded; 897 return gen_policy()->mem_allocate_work(size /* size */, 898 true /* is_tlab */, 899 &gc_overhead_limit_was_exceeded); 900 } 901 902 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 903 // from the list headed by "*prev_ptr". 904 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 905 bool first = true; 906 size_t min_size = 0; // "first" makes this conceptually infinite. 907 ScratchBlock **smallest_ptr, *smallest; 908 ScratchBlock *cur = *prev_ptr; 909 while (cur) { 910 assert(*prev_ptr == cur, "just checking"); 911 if (first || cur->num_words < min_size) { 912 smallest_ptr = prev_ptr; 913 smallest = cur; 914 min_size = smallest->num_words; 915 first = false; 916 } 917 prev_ptr = &cur->next; 918 cur = cur->next; 919 } 920 smallest = *smallest_ptr; 921 *smallest_ptr = smallest->next; 922 return smallest; 923 } 924 925 // Sort the scratch block list headed by res into decreasing size order, 926 // and set "res" to the result. 927 static void sort_scratch_list(ScratchBlock*& list) { 928 ScratchBlock* sorted = NULL; 929 ScratchBlock* unsorted = list; 930 while (unsorted) { 931 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 932 smallest->next = sorted; 933 sorted = smallest; 934 } 935 list = sorted; 936 } 937 938 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 939 size_t max_alloc_words) { 940 ScratchBlock* res = NULL; 941 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 942 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 943 sort_scratch_list(res); 944 return res; 945 } 946 947 void GenCollectedHeap::release_scratch() { 948 _young_gen->reset_scratch(); 949 _old_gen->reset_scratch(); 950 } 951 952 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 953 void do_generation(Generation* gen) { 954 gen->prepare_for_verify(); 955 } 956 }; 957 958 void GenCollectedHeap::prepare_for_verify() { 959 ensure_parsability(false); // no need to retire TLABs 960 GenPrepareForVerifyClosure blk; 961 generation_iterate(&blk, false); 962 } 963 964 void GenCollectedHeap::generation_iterate(GenClosure* cl, 965 bool old_to_young) { 966 if (old_to_young) { 967 cl->do_generation(_old_gen); 968 cl->do_generation(_young_gen); 969 } else { 970 cl->do_generation(_young_gen); 971 cl->do_generation(_old_gen); 972 } 973 } 974 975 bool GenCollectedHeap::is_maximal_no_gc() const { 976 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 977 } 978 979 void GenCollectedHeap::save_marks() { 980 _young_gen->save_marks(); 981 _old_gen->save_marks(); 982 } 983 984 GenCollectedHeap* GenCollectedHeap::heap() { 985 CollectedHeap* heap = Universe::heap(); 986 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 987 assert(heap->kind() == CollectedHeap::GenCollectedHeap || 988 heap->kind() == CollectedHeap::CMSHeap, "Not a GenCollectedHeap"); 989 return (GenCollectedHeap*) heap; 990 } 991 992 void GenCollectedHeap::prepare_for_compaction() { 993 // Start by compacting into same gen. 994 CompactPoint cp(_old_gen); 995 _old_gen->prepare_for_compaction(&cp); 996 _young_gen->prepare_for_compaction(&cp); 997 } 998 999 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1000 log_debug(gc, verify)("%s", _old_gen->name()); 1001 _old_gen->verify(); 1002 1003 log_debug(gc, verify)("%s", _old_gen->name()); 1004 _young_gen->verify(); 1005 1006 log_debug(gc, verify)("RemSet"); 1007 rem_set()->verify(); 1008 } 1009 1010 void GenCollectedHeap::print_on(outputStream* st) const { 1011 _young_gen->print_on(st); 1012 _old_gen->print_on(st); 1013 MetaspaceAux::print_on(st); 1014 } 1015 1016 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1017 } 1018 1019 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1020 } 1021 1022 void GenCollectedHeap::print_tracing_info() const { 1023 if (log_is_enabled(Debug, gc, heap, exit)) { 1024 LogStreamHandle(Debug, gc, heap, exit) lsh; 1025 _young_gen->print_summary_info_on(&lsh); 1026 _old_gen->print_summary_info_on(&lsh); 1027 } 1028 } 1029 1030 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1031 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1032 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1033 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1034 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1035 } 1036 1037 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1038 private: 1039 bool _full; 1040 public: 1041 void do_generation(Generation* gen) { 1042 gen->gc_prologue(_full); 1043 } 1044 GenGCPrologueClosure(bool full) : _full(full) {}; 1045 }; 1046 1047 void GenCollectedHeap::gc_prologue(bool full) { 1048 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1049 1050 // Fill TLAB's and such 1051 CollectedHeap::accumulate_statistics_all_tlabs(); 1052 ensure_parsability(true); // retire TLABs 1053 1054 // Walk generations 1055 GenGCPrologueClosure blk(full); 1056 generation_iterate(&blk, false); // not old-to-young. 1057 }; 1058 1059 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1060 private: 1061 bool _full; 1062 public: 1063 void do_generation(Generation* gen) { 1064 gen->gc_epilogue(_full); 1065 } 1066 GenGCEpilogueClosure(bool full) : _full(full) {}; 1067 }; 1068 1069 void GenCollectedHeap::gc_epilogue(bool full) { 1070 #if defined(COMPILER2) || INCLUDE_JVMCI 1071 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1072 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1073 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1074 #endif /* COMPILER2 || INCLUDE_JVMCI */ 1075 1076 resize_all_tlabs(); 1077 1078 GenGCEpilogueClosure blk(full); 1079 generation_iterate(&blk, false); // not old-to-young. 1080 1081 if (!CleanChunkPoolAsync) { 1082 Chunk::clean_chunk_pool(); 1083 } 1084 1085 MetaspaceCounters::update_performance_counters(); 1086 CompressedClassSpaceCounters::update_performance_counters(); 1087 }; 1088 1089 #ifndef PRODUCT 1090 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1091 private: 1092 public: 1093 void do_generation(Generation* gen) { 1094 gen->record_spaces_top(); 1095 } 1096 }; 1097 1098 void GenCollectedHeap::record_gen_tops_before_GC() { 1099 if (ZapUnusedHeapArea) { 1100 GenGCSaveTopsBeforeGCClosure blk; 1101 generation_iterate(&blk, false); // not old-to-young. 1102 } 1103 } 1104 #endif // not PRODUCT 1105 1106 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1107 public: 1108 void do_generation(Generation* gen) { 1109 gen->ensure_parsability(); 1110 } 1111 }; 1112 1113 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1114 CollectedHeap::ensure_parsability(retire_tlabs); 1115 GenEnsureParsabilityClosure ep_cl; 1116 generation_iterate(&ep_cl, false); 1117 } 1118 1119 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1120 oop obj, 1121 size_t obj_size) { 1122 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1123 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1124 HeapWord* result = NULL; 1125 1126 result = old_gen->expand_and_allocate(obj_size, false); 1127 1128 if (result != NULL) { 1129 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1130 } 1131 return oop(result); 1132 } 1133 1134 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1135 jlong _time; // in ms 1136 jlong _now; // in ms 1137 1138 public: 1139 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1140 1141 jlong time() { return _time; } 1142 1143 void do_generation(Generation* gen) { 1144 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1145 } 1146 }; 1147 1148 jlong GenCollectedHeap::millis_since_last_gc() { 1149 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1150 // provided the underlying platform provides such a time source 1151 // (and it is bug free). So we still have to guard against getting 1152 // back a time later than 'now'. 1153 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1154 GenTimeOfLastGCClosure tolgc_cl(now); 1155 // iterate over generations getting the oldest 1156 // time that a generation was collected 1157 generation_iterate(&tolgc_cl, false); 1158 1159 jlong retVal = now - tolgc_cl.time(); 1160 if (retVal < 0) { 1161 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 1162 ". returning zero instead.", retVal); 1163 return 0; 1164 } 1165 return retVal; 1166 }