1 /* 2 * Copyright (c) 2000, 2018, 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 // While there are no constraints in the GC code that HeapWordSize 75 // be any particular value, there are multiple other areas in the 76 // system which believe this to be true (e.g. oop->object_size in some 77 // cases incorrectly returns the size in wordSize units rather than 78 // HeapWordSize). 79 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 80 81 // Allocate space for the heap. 82 83 char* heap_address; 84 ReservedSpace heap_rs; 85 86 size_t heap_alignment = collector_policy()->heap_alignment(); 87 88 heap_address = allocate(heap_alignment, &heap_rs); 89 90 if (!heap_rs.is_reserved()) { 91 vm_shutdown_during_initialization( 92 "Could not reserve enough space for object heap"); 93 return JNI_ENOMEM; 94 } 95 96 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 97 98 _rem_set = collector_policy()->create_rem_set(reserved_region()); 99 set_barrier_set(rem_set()->bs()); 100 101 ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false); 102 _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set()); 103 heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size()); 104 105 ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false); 106 _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set()); 107 clear_incremental_collection_failed(); 108 109 return JNI_OK; 110 } 111 112 char* GenCollectedHeap::allocate(size_t alignment, 113 ReservedSpace* heap_rs){ 114 // Now figure out the total size. 115 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 116 assert(alignment % pageSize == 0, "Must be"); 117 118 GenerationSpec* young_spec = gen_policy()->young_gen_spec(); 119 GenerationSpec* old_spec = gen_policy()->old_gen_spec(); 120 121 // Check for overflow. 122 size_t total_reserved = young_spec->max_size() + old_spec->max_size(); 123 if (total_reserved < young_spec->max_size()) { 124 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 125 "the maximum representable size"); 126 } 127 assert(total_reserved % alignment == 0, 128 "Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 129 SIZE_FORMAT, total_reserved, alignment); 130 131 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 132 133 os::trace_page_sizes("Heap", 134 collector_policy()->min_heap_byte_size(), 135 total_reserved, 136 alignment, 137 heap_rs->base(), 138 heap_rs->size()); 139 140 return heap_rs->base(); 141 } 142 143 void GenCollectedHeap::post_initialize() { 144 CollectedHeap::post_initialize(); 145 ref_processing_init(); 146 check_gen_kinds(); 147 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 148 149 _gen_policy->initialize_size_policy(def_new_gen->eden()->capacity(), 150 _old_gen->capacity(), 151 def_new_gen->from()->capacity()); 152 _gen_policy->initialize_gc_policy_counters(); 153 } 154 155 void GenCollectedHeap::ref_processing_init() { 156 _young_gen->ref_processor_init(); 157 _old_gen->ref_processor_init(); 158 } 159 160 size_t GenCollectedHeap::capacity() const { 161 return _young_gen->capacity() + _old_gen->capacity(); 162 } 163 164 size_t GenCollectedHeap::used() const { 165 return _young_gen->used() + _old_gen->used(); 166 } 167 168 void GenCollectedHeap::save_used_regions() { 169 _old_gen->save_used_region(); 170 _young_gen->save_used_region(); 171 } 172 173 size_t GenCollectedHeap::max_capacity() const { 174 return _young_gen->max_capacity() + _old_gen->max_capacity(); 175 } 176 177 // Update the _full_collections_completed counter 178 // at the end of a stop-world full GC. 179 unsigned int GenCollectedHeap::update_full_collections_completed() { 180 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 181 assert(_full_collections_completed <= _total_full_collections, 182 "Can't complete more collections than were started"); 183 _full_collections_completed = _total_full_collections; 184 ml.notify_all(); 185 return _full_collections_completed; 186 } 187 188 // Update the _full_collections_completed counter, as appropriate, 189 // at the end of a concurrent GC cycle. Note the conditional update 190 // below to allow this method to be called by a concurrent collector 191 // without synchronizing in any manner with the VM thread (which 192 // may already have initiated a STW full collection "concurrently"). 193 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 194 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 195 assert((_full_collections_completed <= _total_full_collections) && 196 (count <= _total_full_collections), 197 "Can't complete more collections than were started"); 198 if (count > _full_collections_completed) { 199 _full_collections_completed = count; 200 ml.notify_all(); 201 } 202 return _full_collections_completed; 203 } 204 205 206 #ifndef PRODUCT 207 // Override of memory state checking method in CollectedHeap: 208 // Some collectors (CMS for example) can't have badHeapWordVal written 209 // in the first two words of an object. (For instance , in the case of 210 // CMS these words hold state used to synchronize between certain 211 // (concurrent) GC steps and direct allocating mutators.) 212 // The skip_header_HeapWords() method below, allows us to skip 213 // over the requisite number of HeapWord's. Note that (for 214 // generational collectors) this means that those many words are 215 // skipped in each object, irrespective of the generation in which 216 // that object lives. The resultant loss of precision seems to be 217 // harmless and the pain of avoiding that imprecision appears somewhat 218 // higher than we are prepared to pay for such rudimentary debugging 219 // support. 220 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 221 size_t size) { 222 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 223 // We are asked to check a size in HeapWords, 224 // but the memory is mangled in juint words. 225 juint* start = (juint*) (addr + skip_header_HeapWords()); 226 juint* end = (juint*) (addr + size); 227 for (juint* slot = start; slot < end; slot += 1) { 228 assert(*slot == badHeapWordVal, 229 "Found non badHeapWordValue in pre-allocation check"); 230 } 231 } 232 } 233 #endif 234 235 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 236 bool is_tlab, 237 bool first_only) { 238 HeapWord* res = NULL; 239 240 if (_young_gen->should_allocate(size, is_tlab)) { 241 res = _young_gen->allocate(size, is_tlab); 242 if (res != NULL || first_only) { 243 return res; 244 } 245 } 246 247 if (_old_gen->should_allocate(size, is_tlab)) { 248 res = _old_gen->allocate(size, is_tlab); 249 } 250 251 return res; 252 } 253 254 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 255 bool* gc_overhead_limit_was_exceeded) { 256 return gen_policy()->mem_allocate_work(size, 257 false /* is_tlab */, 258 gc_overhead_limit_was_exceeded); 259 } 260 261 bool GenCollectedHeap::must_clear_all_soft_refs() { 262 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || 263 _gc_cause == GCCause::_wb_full_gc; 264 } 265 266 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 267 bool is_tlab, bool run_verification, bool clear_soft_refs, 268 bool restore_marks_for_biased_locking) { 269 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 270 GCTraceTime(Trace, gc, phases) t1(title); 271 TraceCollectorStats tcs(gen->counters()); 272 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause()); 273 274 gen->stat_record()->invocations++; 275 gen->stat_record()->accumulated_time.start(); 276 277 // Must be done anew before each collection because 278 // a previous collection will do mangling and will 279 // change top of some spaces. 280 record_gen_tops_before_GC(); 281 282 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 283 284 if (run_verification && VerifyBeforeGC) { 285 HandleMark hm; // Discard invalid handles created during verification 286 Universe::verify("Before GC"); 287 } 288 COMPILER2_PRESENT(DerivedPointerTable::clear()); 289 290 if (restore_marks_for_biased_locking) { 291 // We perform this mark word preservation work lazily 292 // because it's only at this point that we know whether we 293 // absolutely have to do it; we want to avoid doing it for 294 // scavenge-only collections where it's unnecessary 295 BiasedLocking::preserve_marks(); 296 } 297 298 // Do collection work 299 { 300 // Note on ref discovery: For what appear to be historical reasons, 301 // GCH enables and disabled (by enqueing) refs discovery. 302 // In the future this should be moved into the generation's 303 // collect method so that ref discovery and enqueueing concerns 304 // are local to a generation. The collect method could return 305 // an appropriate indication in the case that notification on 306 // the ref lock was needed. This will make the treatment of 307 // weak refs more uniform (and indeed remove such concerns 308 // from GCH). XXX 309 310 HandleMark hm; // Discard invalid handles created during gc 311 save_marks(); // save marks for all gens 312 // We want to discover references, but not process them yet. 313 // This mode is disabled in process_discovered_references if the 314 // generation does some collection work, or in 315 // enqueue_discovered_references if the generation returns 316 // without doing any work. 317 ReferenceProcessor* rp = gen->ref_processor(); 318 // If the discovery of ("weak") refs in this generation is 319 // atomic wrt other collectors in this configuration, we 320 // are guaranteed to have empty discovered ref lists. 321 if (rp->discovery_is_atomic()) { 322 rp->enable_discovery(); 323 rp->setup_policy(clear_soft_refs); 324 } else { 325 // collect() below will enable discovery as appropriate 326 } 327 gen->collect(full, clear_soft_refs, size, is_tlab); 328 if (!rp->enqueuing_is_done()) { 329 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q()); 330 rp->enqueue_discovered_references(NULL, &pt); 331 pt.print_enqueue_phase(); 332 } else { 333 rp->set_enqueuing_is_done(false); 334 } 335 rp->verify_no_references_recorded(); 336 } 337 338 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 339 340 gen->stat_record()->accumulated_time.stop(); 341 342 update_gc_stats(gen, full); 343 344 if (run_verification && VerifyAfterGC) { 345 HandleMark hm; // Discard invalid handles created during verification 346 Universe::verify("After GC"); 347 } 348 } 349 350 void GenCollectedHeap::do_collection(bool full, 351 bool clear_all_soft_refs, 352 size_t size, 353 bool is_tlab, 354 GenerationType max_generation) { 355 ResourceMark rm; 356 DEBUG_ONLY(Thread* my_thread = Thread::current();) 357 358 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 359 assert(my_thread->is_VM_thread() || 360 my_thread->is_ConcurrentGC_thread(), 361 "incorrect thread type capability"); 362 assert(Heap_lock->is_locked(), 363 "the requesting thread should have the Heap_lock"); 364 guarantee(!is_gc_active(), "collection is not reentrant"); 365 366 if (GCLocker::check_active_before_gc()) { 367 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 368 } 369 370 GCIdMark gc_id_mark; 371 372 const bool do_clear_all_soft_refs = clear_all_soft_refs || 373 collector_policy()->should_clear_all_soft_refs(); 374 375 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 376 377 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 378 379 print_heap_before_gc(); 380 381 { 382 FlagSetting fl(_is_gc_active, true); 383 384 bool complete = full && (max_generation == OldGen); 385 bool old_collects_young = complete && !ScavengeBeforeFullGC; 386 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 387 388 FormatBuffer<> gc_string("%s", "Pause "); 389 if (do_young_collection) { 390 gc_string.append("Young"); 391 } else { 392 gc_string.append("Full"); 393 } 394 395 GCTraceCPUTime tcpu; 396 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true); 397 398 gc_prologue(complete); 399 increment_total_collections(complete); 400 401 size_t young_prev_used = _young_gen->used(); 402 size_t old_prev_used = _old_gen->used(); 403 404 bool run_verification = total_collections() >= VerifyGCStartAt; 405 406 bool prepared_for_verification = false; 407 bool collected_old = false; 408 409 if (do_young_collection) { 410 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 411 prepare_for_verify(); 412 prepared_for_verification = true; 413 } 414 415 collect_generation(_young_gen, 416 full, 417 size, 418 is_tlab, 419 run_verification && VerifyGCLevel <= 0, 420 do_clear_all_soft_refs, 421 false); 422 423 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 424 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 425 // Allocation request was met by young GC. 426 size = 0; 427 } 428 } 429 430 bool must_restore_marks_for_biased_locking = false; 431 432 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 433 if (!complete) { 434 // The full_collections increment was missed above. 435 increment_total_full_collections(); 436 } 437 438 if (!prepared_for_verification && run_verification && 439 VerifyGCLevel <= 1 && VerifyBeforeGC) { 440 prepare_for_verify(); 441 } 442 443 if (do_young_collection) { 444 // We did a young GC. Need a new GC id for the old GC. 445 GCIdMark gc_id_mark; 446 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 447 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 448 } else { 449 // No young GC done. Use the same GC id as was set up earlier in this method. 450 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 451 } 452 453 must_restore_marks_for_biased_locking = true; 454 collected_old = true; 455 } 456 457 // Update "complete" boolean wrt what actually transpired -- 458 // for instance, a promotion failure could have led to 459 // a whole heap collection. 460 complete = complete || collected_old; 461 462 print_heap_change(young_prev_used, old_prev_used); 463 MetaspaceAux::print_metaspace_change(metadata_prev_used); 464 465 // Adjust generation sizes. 466 if (collected_old) { 467 _old_gen->compute_new_size(); 468 } 469 _young_gen->compute_new_size(); 470 471 if (complete) { 472 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 473 ClassLoaderDataGraph::purge(); 474 MetaspaceAux::verify_metrics(); 475 // Resize the metaspace capacity after full collections 476 MetaspaceGC::compute_new_size(); 477 update_full_collections_completed(); 478 } 479 480 // Track memory usage and detect low memory after GC finishes 481 MemoryService::track_memory_usage(); 482 483 gc_epilogue(complete); 484 485 if (must_restore_marks_for_biased_locking) { 486 BiasedLocking::restore_marks(); 487 } 488 } 489 490 print_heap_after_gc(); 491 492 #ifdef TRACESPINNING 493 ParallelTaskTerminator::print_termination_counts(); 494 #endif 495 } 496 497 void GenCollectedHeap::register_nmethod(nmethod* nm) { 498 CodeCache::register_scavenge_root_nmethod(nm); 499 } 500 501 void GenCollectedHeap::verify_nmethod(nmethod* nm) { 502 CodeCache::verify_scavenge_root_nmethod(nm); 503 } 504 505 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 506 return gen_policy()->satisfy_failed_allocation(size, is_tlab); 507 } 508 509 #ifdef ASSERT 510 class AssertNonScavengableClosure: public OopClosure { 511 public: 512 virtual void do_oop(oop* p) { 513 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 514 "Referent should not be scavengable."); } 515 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 516 }; 517 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 518 #endif 519 520 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 521 ScanningOption so, 522 OopClosure* strong_roots, 523 OopClosure* weak_roots, 524 CLDClosure* strong_cld_closure, 525 CLDClosure* weak_cld_closure, 526 CodeBlobToOopClosure* code_roots) { 527 // General roots. 528 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 529 assert(code_roots != NULL, "code root closure should always be set"); 530 // _n_termination for _process_strong_tasks should be set up stream 531 // in a method not running in a GC worker. Otherwise the GC worker 532 // could be trying to change the termination condition while the task 533 // is executing in another GC worker. 534 535 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 536 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 537 } 538 539 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 540 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 541 542 bool is_par = scope->n_threads() > 1; 543 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p); 544 545 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 546 Universe::oops_do(strong_roots); 547 } 548 // Global (strong) JNI handles 549 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 550 JNIHandles::oops_do(strong_roots); 551 } 552 553 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 554 ObjectSynchronizer::oops_do(strong_roots); 555 } 556 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 557 Management::oops_do(strong_roots); 558 } 559 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 560 JvmtiExport::oops_do(strong_roots); 561 } 562 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) { 563 AOTLoader::oops_do(strong_roots); 564 } 565 566 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 567 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 568 } 569 570 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 571 if (so & SO_ScavengeCodeCache) { 572 assert(code_roots != NULL, "must supply closure for code cache"); 573 574 // We only visit parts of the CodeCache when scavenging. 575 CodeCache::scavenge_root_nmethods_do(code_roots); 576 } 577 if (so & SO_AllCodeCache) { 578 assert(code_roots != NULL, "must supply closure for code cache"); 579 580 // CMSCollector uses this to do intermediate-strength collections. 581 // We scan the entire code cache, since CodeCache::do_unloading is not called. 582 CodeCache::blobs_do(code_roots); 583 } 584 // Verify that the code cache contents are not subject to 585 // movement by a scavenging collection. 586 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 587 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 588 } 589 } 590 591 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope, 592 OopClosure* root_closure) { 593 assert(root_closure != NULL, "Must be set"); 594 // All threads execute the following. A specific chunk of buckets 595 // from the StringTable are the individual tasks. 596 if (scope->n_threads() > 1) { 597 StringTable::possibly_parallel_oops_do(root_closure); 598 } else { 599 StringTable::oops_do(root_closure); 600 } 601 } 602 603 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope, 604 OopsInGenClosure* root_closure, 605 OopsInGenClosure* old_gen_closure, 606 CLDClosure* cld_closure) { 607 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations); 608 609 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure, 610 cld_closure, cld_closure, &mark_code_closure); 611 process_string_table_roots(scope, root_closure); 612 613 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 614 root_closure->reset_generation(); 615 } 616 617 // When collection is parallel, all threads get to cooperate to do 618 // old generation scanning. 619 old_gen_closure->set_generation(_old_gen); 620 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); 621 old_gen_closure->reset_generation(); 622 623 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 624 } 625 626 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope, 627 bool is_adjust_phase, 628 ScanningOption so, 629 bool only_strong_roots, 630 OopsInGenClosure* root_closure, 631 CLDClosure* cld_closure) { 632 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase); 633 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure; 634 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 635 636 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure); 637 if (is_adjust_phase) { 638 // We never treat the string table as roots during marking 639 // for the full gc, so we only need to process it during 640 // the adjust phase. 641 process_string_table_roots(scope, root_closure); 642 } 643 644 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 645 } 646 647 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 648 WeakProcessor::oops_do(root_closure); 649 _young_gen->ref_processor()->weak_oops_do(root_closure); 650 _old_gen->ref_processor()->weak_oops_do(root_closure); 651 } 652 653 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 654 void GenCollectedHeap:: \ 655 oop_since_save_marks_iterate(GenerationType gen, \ 656 OopClosureType* cur, \ 657 OopClosureType* older) { \ 658 if (gen == YoungGen) { \ 659 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 660 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 661 } else { \ 662 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 663 } \ 664 } 665 666 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 667 668 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 669 670 bool GenCollectedHeap::no_allocs_since_save_marks() { 671 return _young_gen->no_allocs_since_save_marks() && 672 _old_gen->no_allocs_since_save_marks(); 673 } 674 675 bool GenCollectedHeap::supports_inline_contig_alloc() const { 676 return _young_gen->supports_inline_contig_alloc(); 677 } 678 679 HeapWord* volatile* GenCollectedHeap::top_addr() const { 680 return _young_gen->top_addr(); 681 } 682 683 HeapWord** GenCollectedHeap::end_addr() const { 684 return _young_gen->end_addr(); 685 } 686 687 // public collection interfaces 688 689 void GenCollectedHeap::collect(GCCause::Cause cause) { 690 if (cause == GCCause::_wb_young_gc) { 691 // Young collection for the WhiteBox API. 692 collect(cause, YoungGen); 693 } else { 694 #ifdef ASSERT 695 if (cause == GCCause::_scavenge_alot) { 696 // Young collection only. 697 collect(cause, YoungGen); 698 } else { 699 // Stop-the-world full collection. 700 collect(cause, OldGen); 701 } 702 #else 703 // Stop-the-world full collection. 704 collect(cause, OldGen); 705 #endif 706 } 707 } 708 709 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 710 // The caller doesn't have the Heap_lock 711 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 712 MutexLocker ml(Heap_lock); 713 collect_locked(cause, max_generation); 714 } 715 716 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 717 // The caller has the Heap_lock 718 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 719 collect_locked(cause, OldGen); 720 } 721 722 // this is the private collection interface 723 // The Heap_lock is expected to be held on entry. 724 725 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 726 // Read the GC count while holding the Heap_lock 727 unsigned int gc_count_before = total_collections(); 728 unsigned int full_gc_count_before = total_full_collections(); 729 { 730 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 731 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 732 cause, max_generation); 733 VMThread::execute(&op); 734 } 735 } 736 737 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 738 do_full_collection(clear_all_soft_refs, OldGen); 739 } 740 741 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 742 GenerationType last_generation) { 743 GenerationType local_last_generation; 744 if (!incremental_collection_will_fail(false /* don't consult_young */) && 745 gc_cause() == GCCause::_gc_locker) { 746 local_last_generation = YoungGen; 747 } else { 748 local_last_generation = last_generation; 749 } 750 751 do_collection(true, // full 752 clear_all_soft_refs, // clear_all_soft_refs 753 0, // size 754 false, // is_tlab 755 local_last_generation); // last_generation 756 // Hack XXX FIX ME !!! 757 // A scavenge may not have been attempted, or may have 758 // been attempted and failed, because the old gen was too full 759 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 760 incremental_collection_will_fail(false /* don't consult_young */)) { 761 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 762 // This time allow the old gen to be collected as well 763 do_collection(true, // full 764 clear_all_soft_refs, // clear_all_soft_refs 765 0, // size 766 false, // is_tlab 767 OldGen); // last_generation 768 } 769 } 770 771 bool GenCollectedHeap::is_in_young(oop p) { 772 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 773 assert(result == _young_gen->is_in_reserved(p), 774 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 775 return result; 776 } 777 778 // Returns "TRUE" iff "p" points into the committed areas of the heap. 779 bool GenCollectedHeap::is_in(const void* p) const { 780 return _young_gen->is_in(p) || _old_gen->is_in(p); 781 } 782 783 #ifdef ASSERT 784 // Don't implement this by using is_in_young(). This method is used 785 // in some cases to check that is_in_young() is correct. 786 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 787 assert(is_in_reserved(p) || p == NULL, 788 "Does not work if address is non-null and outside of the heap"); 789 return p < _young_gen->reserved().end() && p != NULL; 790 } 791 #endif 792 793 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 794 NoHeaderExtendedOopClosure no_header_cl(cl); 795 oop_iterate(&no_header_cl); 796 } 797 798 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 799 _young_gen->oop_iterate(cl); 800 _old_gen->oop_iterate(cl); 801 } 802 803 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 804 _young_gen->object_iterate(cl); 805 _old_gen->object_iterate(cl); 806 } 807 808 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 809 _young_gen->safe_object_iterate(cl); 810 _old_gen->safe_object_iterate(cl); 811 } 812 813 Space* GenCollectedHeap::space_containing(const void* addr) const { 814 Space* res = _young_gen->space_containing(addr); 815 if (res != NULL) { 816 return res; 817 } 818 res = _old_gen->space_containing(addr); 819 assert(res != NULL, "Could not find containing space"); 820 return res; 821 } 822 823 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 824 assert(is_in_reserved(addr), "block_start of address outside of heap"); 825 if (_young_gen->is_in_reserved(addr)) { 826 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 827 return _young_gen->block_start(addr); 828 } 829 830 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 831 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 832 return _old_gen->block_start(addr); 833 } 834 835 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 836 assert(is_in_reserved(addr), "block_size of address outside of heap"); 837 if (_young_gen->is_in_reserved(addr)) { 838 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 839 return _young_gen->block_size(addr); 840 } 841 842 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 843 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 844 return _old_gen->block_size(addr); 845 } 846 847 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 848 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 849 assert(block_start(addr) == addr, "addr must be a block start"); 850 if (_young_gen->is_in_reserved(addr)) { 851 return _young_gen->block_is_obj(addr); 852 } 853 854 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 855 return _old_gen->block_is_obj(addr); 856 } 857 858 bool GenCollectedHeap::supports_tlab_allocation() const { 859 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 860 return _young_gen->supports_tlab_allocation(); 861 } 862 863 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 864 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 865 if (_young_gen->supports_tlab_allocation()) { 866 return _young_gen->tlab_capacity(); 867 } 868 return 0; 869 } 870 871 size_t GenCollectedHeap::tlab_used(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_used(); 875 } 876 return 0; 877 } 878 879 size_t GenCollectedHeap::unsafe_max_tlab_alloc(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->unsafe_max_tlab_alloc(); 883 } 884 return 0; 885 } 886 887 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 888 bool gc_overhead_limit_was_exceeded; 889 return gen_policy()->mem_allocate_work(size /* size */, 890 true /* is_tlab */, 891 &gc_overhead_limit_was_exceeded); 892 } 893 894 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 895 // from the list headed by "*prev_ptr". 896 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 897 bool first = true; 898 size_t min_size = 0; // "first" makes this conceptually infinite. 899 ScratchBlock **smallest_ptr, *smallest; 900 ScratchBlock *cur = *prev_ptr; 901 while (cur) { 902 assert(*prev_ptr == cur, "just checking"); 903 if (first || cur->num_words < min_size) { 904 smallest_ptr = prev_ptr; 905 smallest = cur; 906 min_size = smallest->num_words; 907 first = false; 908 } 909 prev_ptr = &cur->next; 910 cur = cur->next; 911 } 912 smallest = *smallest_ptr; 913 *smallest_ptr = smallest->next; 914 return smallest; 915 } 916 917 // Sort the scratch block list headed by res into decreasing size order, 918 // and set "res" to the result. 919 static void sort_scratch_list(ScratchBlock*& list) { 920 ScratchBlock* sorted = NULL; 921 ScratchBlock* unsorted = list; 922 while (unsorted) { 923 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 924 smallest->next = sorted; 925 sorted = smallest; 926 } 927 list = sorted; 928 } 929 930 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 931 size_t max_alloc_words) { 932 ScratchBlock* res = NULL; 933 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 934 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 935 sort_scratch_list(res); 936 return res; 937 } 938 939 void GenCollectedHeap::release_scratch() { 940 _young_gen->reset_scratch(); 941 _old_gen->reset_scratch(); 942 } 943 944 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 945 void do_generation(Generation* gen) { 946 gen->prepare_for_verify(); 947 } 948 }; 949 950 void GenCollectedHeap::prepare_for_verify() { 951 ensure_parsability(false); // no need to retire TLABs 952 GenPrepareForVerifyClosure blk; 953 generation_iterate(&blk, false); 954 } 955 956 void GenCollectedHeap::generation_iterate(GenClosure* cl, 957 bool old_to_young) { 958 if (old_to_young) { 959 cl->do_generation(_old_gen); 960 cl->do_generation(_young_gen); 961 } else { 962 cl->do_generation(_young_gen); 963 cl->do_generation(_old_gen); 964 } 965 } 966 967 bool GenCollectedHeap::is_maximal_no_gc() const { 968 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 969 } 970 971 void GenCollectedHeap::save_marks() { 972 _young_gen->save_marks(); 973 _old_gen->save_marks(); 974 } 975 976 GenCollectedHeap* GenCollectedHeap::heap() { 977 CollectedHeap* heap = Universe::heap(); 978 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 979 assert(heap->kind() == CollectedHeap::SerialHeap || 980 heap->kind() == CollectedHeap::CMSHeap, "Not a GenCollectedHeap"); 981 return (GenCollectedHeap*) heap; 982 } 983 984 void GenCollectedHeap::prepare_for_compaction() { 985 // Start by compacting into same gen. 986 CompactPoint cp(_old_gen); 987 _old_gen->prepare_for_compaction(&cp); 988 _young_gen->prepare_for_compaction(&cp); 989 } 990 991 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 992 log_debug(gc, verify)("%s", _old_gen->name()); 993 _old_gen->verify(); 994 995 log_debug(gc, verify)("%s", _old_gen->name()); 996 _young_gen->verify(); 997 998 log_debug(gc, verify)("RemSet"); 999 rem_set()->verify(); 1000 } 1001 1002 void GenCollectedHeap::print_on(outputStream* st) const { 1003 _young_gen->print_on(st); 1004 _old_gen->print_on(st); 1005 MetaspaceAux::print_on(st); 1006 } 1007 1008 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1009 } 1010 1011 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1012 } 1013 1014 void GenCollectedHeap::print_tracing_info() const { 1015 if (log_is_enabled(Debug, gc, heap, exit)) { 1016 LogStreamHandle(Debug, gc, heap, exit) lsh; 1017 _young_gen->print_summary_info_on(&lsh); 1018 _old_gen->print_summary_info_on(&lsh); 1019 } 1020 } 1021 1022 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1023 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1024 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1025 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1026 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1027 } 1028 1029 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1030 private: 1031 bool _full; 1032 public: 1033 void do_generation(Generation* gen) { 1034 gen->gc_prologue(_full); 1035 } 1036 GenGCPrologueClosure(bool full) : _full(full) {}; 1037 }; 1038 1039 void GenCollectedHeap::gc_prologue(bool full) { 1040 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1041 1042 // Fill TLAB's and such 1043 CollectedHeap::accumulate_statistics_all_tlabs(); 1044 ensure_parsability(true); // retire TLABs 1045 1046 // Walk generations 1047 GenGCPrologueClosure blk(full); 1048 generation_iterate(&blk, false); // not old-to-young. 1049 }; 1050 1051 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1052 private: 1053 bool _full; 1054 public: 1055 void do_generation(Generation* gen) { 1056 gen->gc_epilogue(_full); 1057 } 1058 GenGCEpilogueClosure(bool full) : _full(full) {}; 1059 }; 1060 1061 void GenCollectedHeap::gc_epilogue(bool full) { 1062 #if COMPILER2_OR_JVMCI 1063 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1064 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1065 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1066 #endif // COMPILER2_OR_JVMCI 1067 1068 resize_all_tlabs(); 1069 1070 GenGCEpilogueClosure blk(full); 1071 generation_iterate(&blk, false); // not old-to-young. 1072 1073 if (!CleanChunkPoolAsync) { 1074 Chunk::clean_chunk_pool(); 1075 } 1076 1077 MetaspaceCounters::update_performance_counters(); 1078 CompressedClassSpaceCounters::update_performance_counters(); 1079 }; 1080 1081 #ifndef PRODUCT 1082 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1083 private: 1084 public: 1085 void do_generation(Generation* gen) { 1086 gen->record_spaces_top(); 1087 } 1088 }; 1089 1090 void GenCollectedHeap::record_gen_tops_before_GC() { 1091 if (ZapUnusedHeapArea) { 1092 GenGCSaveTopsBeforeGCClosure blk; 1093 generation_iterate(&blk, false); // not old-to-young. 1094 } 1095 } 1096 #endif // not PRODUCT 1097 1098 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1099 public: 1100 void do_generation(Generation* gen) { 1101 gen->ensure_parsability(); 1102 } 1103 }; 1104 1105 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1106 CollectedHeap::ensure_parsability(retire_tlabs); 1107 GenEnsureParsabilityClosure ep_cl; 1108 generation_iterate(&ep_cl, false); 1109 } 1110 1111 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1112 oop obj, 1113 size_t obj_size) { 1114 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1115 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1116 HeapWord* result = NULL; 1117 1118 result = old_gen->expand_and_allocate(obj_size, false); 1119 1120 if (result != NULL) { 1121 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1122 } 1123 return oop(result); 1124 } 1125 1126 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1127 jlong _time; // in ms 1128 jlong _now; // in ms 1129 1130 public: 1131 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1132 1133 jlong time() { return _time; } 1134 1135 void do_generation(Generation* gen) { 1136 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1137 } 1138 }; 1139 1140 jlong GenCollectedHeap::millis_since_last_gc() { 1141 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1142 // provided the underlying platform provides such a time source 1143 // (and it is bug free). So we still have to guard against getting 1144 // back a time later than 'now'. 1145 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1146 GenTimeOfLastGCClosure tolgc_cl(now); 1147 // iterate over generations getting the oldest 1148 // time that a generation was collected 1149 generation_iterate(&tolgc_cl, false); 1150 1151 jlong retVal = now - tolgc_cl.time(); 1152 if (retVal < 0) { 1153 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 1154 ". returning zero instead.", retVal); 1155 return 0; 1156 } 1157 return retVal; 1158 }