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::ref_processing_init() { 157 _young_gen->ref_processor_init(); 158 _old_gen->ref_processor_init(); 159 } 160 161 size_t GenCollectedHeap::capacity() const { 162 return _young_gen->capacity() + _old_gen->capacity(); 163 } 164 165 size_t GenCollectedHeap::used() const { 166 return _young_gen->used() + _old_gen->used(); 167 } 168 169 void GenCollectedHeap::save_used_regions() { 170 _old_gen->save_used_region(); 171 _young_gen->save_used_region(); 172 } 173 174 size_t GenCollectedHeap::max_capacity() const { 175 return _young_gen->max_capacity() + _old_gen->max_capacity(); 176 } 177 178 // Update the _full_collections_completed counter 179 // at the end of a stop-world full GC. 180 unsigned int GenCollectedHeap::update_full_collections_completed() { 181 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 182 assert(_full_collections_completed <= _total_full_collections, 183 "Can't complete more collections than were started"); 184 _full_collections_completed = _total_full_collections; 185 ml.notify_all(); 186 return _full_collections_completed; 187 } 188 189 // Update the _full_collections_completed counter, as appropriate, 190 // at the end of a concurrent GC cycle. Note the conditional update 191 // below to allow this method to be called by a concurrent collector 192 // without synchronizing in any manner with the VM thread (which 193 // may already have initiated a STW full collection "concurrently"). 194 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 195 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 196 assert((_full_collections_completed <= _total_full_collections) && 197 (count <= _total_full_collections), 198 "Can't complete more collections than were started"); 199 if (count > _full_collections_completed) { 200 _full_collections_completed = count; 201 ml.notify_all(); 202 } 203 return _full_collections_completed; 204 } 205 206 207 #ifndef PRODUCT 208 // Override of memory state checking method in CollectedHeap: 209 // Some collectors (CMS for example) can't have badHeapWordVal written 210 // in the first two words of an object. (For instance , in the case of 211 // CMS these words hold state used to synchronize between certain 212 // (concurrent) GC steps and direct allocating mutators.) 213 // The skip_header_HeapWords() method below, allows us to skip 214 // over the requisite number of HeapWord's. Note that (for 215 // generational collectors) this means that those many words are 216 // skipped in each object, irrespective of the generation in which 217 // that object lives. The resultant loss of precision seems to be 218 // harmless and the pain of avoiding that imprecision appears somewhat 219 // higher than we are prepared to pay for such rudimentary debugging 220 // support. 221 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 222 size_t size) { 223 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 224 // We are asked to check a size in HeapWords, 225 // but the memory is mangled in juint words. 226 juint* start = (juint*) (addr + skip_header_HeapWords()); 227 juint* end = (juint*) (addr + size); 228 for (juint* slot = start; slot < end; slot += 1) { 229 assert(*slot == badHeapWordVal, 230 "Found non badHeapWordValue in pre-allocation check"); 231 } 232 } 233 } 234 #endif 235 236 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 237 bool is_tlab, 238 bool first_only) { 239 HeapWord* res = NULL; 240 241 if (_young_gen->should_allocate(size, is_tlab)) { 242 res = _young_gen->allocate(size, is_tlab); 243 if (res != NULL || first_only) { 244 return res; 245 } 246 } 247 248 if (_old_gen->should_allocate(size, is_tlab)) { 249 res = _old_gen->allocate(size, is_tlab); 250 } 251 252 return res; 253 } 254 255 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 256 bool* gc_overhead_limit_was_exceeded) { 257 return gen_policy()->mem_allocate_work(size, 258 false /* is_tlab */, 259 gc_overhead_limit_was_exceeded); 260 } 261 262 bool GenCollectedHeap::must_clear_all_soft_refs() { 263 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || 264 _gc_cause == GCCause::_wb_full_gc; 265 } 266 267 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 268 bool is_tlab, bool run_verification, bool clear_soft_refs, 269 bool restore_marks_for_biased_locking) { 270 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 271 GCTraceTime(Trace, gc, phases) t1(title); 272 TraceCollectorStats tcs(gen->counters()); 273 TraceMemoryManagerStats tmms(gen->kind(),gc_cause()); 274 275 gen->stat_record()->invocations++; 276 gen->stat_record()->accumulated_time.start(); 277 278 // Must be done anew before each collection because 279 // a previous collection will do mangling and will 280 // change top of some spaces. 281 record_gen_tops_before_GC(); 282 283 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 284 285 if (run_verification && VerifyBeforeGC) { 286 HandleMark hm; // Discard invalid handles created during verification 287 Universe::verify("Before GC"); 288 } 289 COMPILER2_PRESENT(DerivedPointerTable::clear()); 290 291 if (restore_marks_for_biased_locking) { 292 // We perform this mark word preservation work lazily 293 // because it's only at this point that we know whether we 294 // absolutely have to do it; we want to avoid doing it for 295 // scavenge-only collections where it's unnecessary 296 BiasedLocking::preserve_marks(); 297 } 298 299 // Do collection work 300 { 301 // Note on ref discovery: For what appear to be historical reasons, 302 // GCH enables and disabled (by enqueing) refs discovery. 303 // In the future this should be moved into the generation's 304 // collect method so that ref discovery and enqueueing concerns 305 // are local to a generation. The collect method could return 306 // an appropriate indication in the case that notification on 307 // the ref lock was needed. This will make the treatment of 308 // weak refs more uniform (and indeed remove such concerns 309 // from GCH). XXX 310 311 HandleMark hm; // Discard invalid handles created during gc 312 save_marks(); // save marks for all gens 313 // We want to discover references, but not process them yet. 314 // This mode is disabled in process_discovered_references if the 315 // generation does some collection work, or in 316 // enqueue_discovered_references if the generation returns 317 // without doing any work. 318 ReferenceProcessor* rp = gen->ref_processor(); 319 // If the discovery of ("weak") refs in this generation is 320 // atomic wrt other collectors in this configuration, we 321 // are guaranteed to have empty discovered ref lists. 322 if (rp->discovery_is_atomic()) { 323 rp->enable_discovery(); 324 rp->setup_policy(clear_soft_refs); 325 } else { 326 // collect() below will enable discovery as appropriate 327 } 328 gen->collect(full, clear_soft_refs, size, is_tlab); 329 if (!rp->enqueuing_is_done()) { 330 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q()); 331 rp->enqueue_discovered_references(NULL, &pt); 332 pt.print_enqueue_phase(); 333 } else { 334 rp->set_enqueuing_is_done(false); 335 } 336 rp->verify_no_references_recorded(); 337 } 338 339 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 340 341 gen->stat_record()->accumulated_time.stop(); 342 343 update_gc_stats(gen, full); 344 345 if (run_verification && VerifyAfterGC) { 346 HandleMark hm; // Discard invalid handles created during verification 347 Universe::verify("After GC"); 348 } 349 } 350 351 void GenCollectedHeap::do_collection(bool full, 352 bool clear_all_soft_refs, 353 size_t size, 354 bool is_tlab, 355 GenerationType max_generation) { 356 ResourceMark rm; 357 DEBUG_ONLY(Thread* my_thread = Thread::current();) 358 359 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 360 assert(my_thread->is_VM_thread() || 361 my_thread->is_ConcurrentGC_thread(), 362 "incorrect thread type capability"); 363 assert(Heap_lock->is_locked(), 364 "the requesting thread should have the Heap_lock"); 365 guarantee(!is_gc_active(), "collection is not reentrant"); 366 367 if (GCLocker::check_active_before_gc()) { 368 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 369 } 370 371 GCIdMarkAndRestore gc_id_mark; 372 373 const bool do_clear_all_soft_refs = clear_all_soft_refs || 374 collector_policy()->should_clear_all_soft_refs(); 375 376 ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy()); 377 378 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 379 380 print_heap_before_gc(); 381 382 { 383 FlagSetting fl(_is_gc_active, true); 384 385 bool complete = full && (max_generation == OldGen); 386 bool old_collects_young = complete && !ScavengeBeforeFullGC; 387 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 388 389 FormatBuffer<> gc_string("%s", "Pause "); 390 if (do_young_collection) { 391 gc_string.append("Young"); 392 } else { 393 gc_string.append("Full"); 394 } 395 396 GCTraceCPUTime tcpu; 397 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true); 398 399 gc_prologue(complete); 400 increment_total_collections(complete); 401 402 size_t young_prev_used = _young_gen->used(); 403 size_t old_prev_used = _old_gen->used(); 404 405 bool run_verification = total_collections() >= VerifyGCStartAt; 406 407 bool prepared_for_verification = false; 408 bool collected_old = false; 409 410 if (do_young_collection) { 411 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 412 prepare_for_verify(); 413 prepared_for_verification = true; 414 } 415 416 collect_generation(_young_gen, 417 full, 418 size, 419 is_tlab, 420 run_verification && VerifyGCLevel <= 0, 421 do_clear_all_soft_refs, 422 false); 423 424 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 425 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 426 // Allocation request was met by young GC. 427 size = 0; 428 } 429 } 430 431 bool must_restore_marks_for_biased_locking = false; 432 433 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 434 if (!complete) { 435 // The full_collections increment was missed above. 436 increment_total_full_collections(); 437 } 438 439 if (!prepared_for_verification && run_verification && 440 VerifyGCLevel <= 1 && VerifyBeforeGC) { 441 prepare_for_verify(); 442 } 443 444 if (do_young_collection) { 445 // We did a young GC. Need a new GC id for the old GC. 446 GCIdMarkAndRestore gc_id_mark; 447 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 448 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 449 } else { 450 // No young GC done. Use the same GC id as was set up earlier in this method. 451 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 452 } 453 454 must_restore_marks_for_biased_locking = true; 455 collected_old = true; 456 } 457 458 // Update "complete" boolean wrt what actually transpired -- 459 // for instance, a promotion failure could have led to 460 // a whole heap collection. 461 complete = complete || collected_old; 462 463 print_heap_change(young_prev_used, old_prev_used); 464 MetaspaceAux::print_metaspace_change(metadata_prev_used); 465 466 // Adjust generation sizes. 467 if (collected_old) { 468 _old_gen->compute_new_size(); 469 } 470 _young_gen->compute_new_size(); 471 472 if (complete) { 473 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 474 ClassLoaderDataGraph::purge(); 475 MetaspaceAux::verify_metrics(); 476 // Resize the metaspace capacity after full collections 477 MetaspaceGC::compute_new_size(); 478 update_full_collections_completed(); 479 } 480 481 // Track memory usage and detect low memory after GC finishes 482 MemoryService::track_memory_usage(); 483 484 gc_epilogue(complete); 485 486 if (must_restore_marks_for_biased_locking) { 487 BiasedLocking::restore_marks(); 488 } 489 } 490 491 print_heap_after_gc(); 492 493 #ifdef TRACESPINNING 494 ParallelTaskTerminator::print_termination_counts(); 495 #endif 496 } 497 498 void GenCollectedHeap::register_nmethod(nmethod* nm) { 499 CodeCache::register_scavenge_root_nmethod(nm); 500 } 501 502 void GenCollectedHeap::verify_nmethod(nmethod* nm) { 503 CodeCache::verify_scavenge_root_nmethod(nm); 504 } 505 506 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 507 return gen_policy()->satisfy_failed_allocation(size, is_tlab); 508 } 509 510 #ifdef ASSERT 511 class AssertNonScavengableClosure: public OopClosure { 512 public: 513 virtual void do_oop(oop* p) { 514 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 515 "Referent should not be scavengable."); } 516 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 517 }; 518 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 519 #endif 520 521 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 522 ScanningOption so, 523 OopClosure* strong_roots, 524 OopClosure* weak_roots, 525 CLDClosure* strong_cld_closure, 526 CLDClosure* weak_cld_closure, 527 CodeBlobToOopClosure* code_roots) { 528 // General roots. 529 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 530 assert(code_roots != NULL, "code root closure should always be set"); 531 // _n_termination for _process_strong_tasks should be set up stream 532 // in a method not running in a GC worker. Otherwise the GC worker 533 // could be trying to change the termination condition while the task 534 // is executing in another GC worker. 535 536 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 537 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 538 } 539 540 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 541 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 542 543 bool is_par = scope->n_threads() > 1; 544 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p); 545 546 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 547 Universe::oops_do(strong_roots); 548 } 549 // Global (strong) JNI handles 550 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 551 JNIHandles::oops_do(strong_roots); 552 } 553 554 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 555 ObjectSynchronizer::oops_do(strong_roots); 556 } 557 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 558 Management::oops_do(strong_roots); 559 } 560 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 561 JvmtiExport::oops_do(strong_roots); 562 } 563 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) { 564 AOTLoader::oops_do(strong_roots); 565 } 566 567 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 568 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 569 } 570 571 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 572 if (so & SO_ScavengeCodeCache) { 573 assert(code_roots != NULL, "must supply closure for code cache"); 574 575 // We only visit parts of the CodeCache when scavenging. 576 CodeCache::scavenge_root_nmethods_do(code_roots); 577 } 578 if (so & SO_AllCodeCache) { 579 assert(code_roots != NULL, "must supply closure for code cache"); 580 581 // CMSCollector uses this to do intermediate-strength collections. 582 // We scan the entire code cache, since CodeCache::do_unloading is not called. 583 CodeCache::blobs_do(code_roots); 584 } 585 // Verify that the code cache contents are not subject to 586 // movement by a scavenging collection. 587 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 588 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 589 } 590 } 591 592 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope, 593 OopClosure* root_closure) { 594 assert(root_closure != NULL, "Must be set"); 595 // All threads execute the following. A specific chunk of buckets 596 // from the StringTable are the individual tasks. 597 if (scope->n_threads() > 1) { 598 StringTable::possibly_parallel_oops_do(root_closure); 599 } else { 600 StringTable::oops_do(root_closure); 601 } 602 } 603 604 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope, 605 OopsInGenClosure* root_closure, 606 OopsInGenClosure* old_gen_closure, 607 CLDClosure* cld_closure) { 608 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations); 609 610 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure, 611 cld_closure, cld_closure, &mark_code_closure); 612 process_string_table_roots(scope, root_closure); 613 614 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 615 root_closure->reset_generation(); 616 } 617 618 // When collection is parallel, all threads get to cooperate to do 619 // old generation scanning. 620 old_gen_closure->set_generation(_old_gen); 621 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); 622 old_gen_closure->reset_generation(); 623 624 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 625 } 626 627 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope, 628 bool is_adjust_phase, 629 ScanningOption so, 630 bool only_strong_roots, 631 OopsInGenClosure* root_closure, 632 CLDClosure* cld_closure) { 633 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase); 634 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure; 635 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 636 637 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure); 638 if (is_adjust_phase) { 639 // We never treat the string table as roots during marking 640 // for the full gc, so we only need to process it during 641 // the adjust phase. 642 process_string_table_roots(scope, root_closure); 643 } 644 645 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 646 } 647 648 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 649 WeakProcessor::oops_do(root_closure); 650 _young_gen->ref_processor()->weak_oops_do(root_closure); 651 _old_gen->ref_processor()->weak_oops_do(root_closure); 652 } 653 654 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 655 void GenCollectedHeap:: \ 656 oop_since_save_marks_iterate(GenerationType gen, \ 657 OopClosureType* cur, \ 658 OopClosureType* older) { \ 659 if (gen == YoungGen) { \ 660 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 661 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 662 } else { \ 663 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 664 } \ 665 } 666 667 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 668 669 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 670 671 bool GenCollectedHeap::no_allocs_since_save_marks() { 672 return _young_gen->no_allocs_since_save_marks() && 673 _old_gen->no_allocs_since_save_marks(); 674 } 675 676 bool GenCollectedHeap::supports_inline_contig_alloc() const { 677 return _young_gen->supports_inline_contig_alloc(); 678 } 679 680 HeapWord* volatile* GenCollectedHeap::top_addr() const { 681 return _young_gen->top_addr(); 682 } 683 684 HeapWord** GenCollectedHeap::end_addr() const { 685 return _young_gen->end_addr(); 686 } 687 688 // public collection interfaces 689 690 void GenCollectedHeap::collect(GCCause::Cause cause) { 691 if (cause == GCCause::_wb_young_gc) { 692 // Young collection for the WhiteBox API. 693 collect(cause, YoungGen); 694 } else { 695 #ifdef ASSERT 696 if (cause == GCCause::_scavenge_alot) { 697 // Young collection only. 698 collect(cause, YoungGen); 699 } else { 700 // Stop-the-world full collection. 701 collect(cause, OldGen); 702 } 703 #else 704 // Stop-the-world full collection. 705 collect(cause, OldGen); 706 #endif 707 } 708 } 709 710 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 711 // The caller doesn't have the Heap_lock 712 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 713 MutexLocker ml(Heap_lock); 714 collect_locked(cause, max_generation); 715 } 716 717 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 718 // The caller has the Heap_lock 719 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 720 collect_locked(cause, OldGen); 721 } 722 723 // this is the private collection interface 724 // The Heap_lock is expected to be held on entry. 725 726 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 727 // Read the GC count while holding the Heap_lock 728 unsigned int gc_count_before = total_collections(); 729 unsigned int full_gc_count_before = total_full_collections(); 730 { 731 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 732 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 733 cause, max_generation); 734 VMThread::execute(&op); 735 } 736 } 737 738 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 739 do_full_collection(clear_all_soft_refs, OldGen); 740 } 741 742 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 743 GenerationType last_generation) { 744 GenerationType local_last_generation; 745 if (!incremental_collection_will_fail(false /* don't consult_young */) && 746 gc_cause() == GCCause::_gc_locker) { 747 local_last_generation = YoungGen; 748 } else { 749 local_last_generation = last_generation; 750 } 751 752 do_collection(true, // full 753 clear_all_soft_refs, // clear_all_soft_refs 754 0, // size 755 false, // is_tlab 756 local_last_generation); // last_generation 757 // Hack XXX FIX ME !!! 758 // A scavenge may not have been attempted, or may have 759 // been attempted and failed, because the old gen was too full 760 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 761 incremental_collection_will_fail(false /* don't consult_young */)) { 762 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 763 // This time allow the old gen to be collected as well 764 do_collection(true, // full 765 clear_all_soft_refs, // clear_all_soft_refs 766 0, // size 767 false, // is_tlab 768 OldGen); // last_generation 769 } 770 } 771 772 bool GenCollectedHeap::is_in_young(oop p) { 773 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 774 assert(result == _young_gen->is_in_reserved(p), 775 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 776 return result; 777 } 778 779 // Returns "TRUE" iff "p" points into the committed areas of the heap. 780 bool GenCollectedHeap::is_in(const void* p) const { 781 return _young_gen->is_in(p) || _old_gen->is_in(p); 782 } 783 784 #ifdef ASSERT 785 // Don't implement this by using is_in_young(). This method is used 786 // in some cases to check that is_in_young() is correct. 787 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 788 assert(is_in_reserved(p) || p == NULL, 789 "Does not work if address is non-null and outside of the heap"); 790 return p < _young_gen->reserved().end() && p != NULL; 791 } 792 #endif 793 794 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 795 NoHeaderExtendedOopClosure no_header_cl(cl); 796 oop_iterate(&no_header_cl); 797 } 798 799 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 800 _young_gen->oop_iterate(cl); 801 _old_gen->oop_iterate(cl); 802 } 803 804 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 805 _young_gen->object_iterate(cl); 806 _old_gen->object_iterate(cl); 807 } 808 809 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 810 _young_gen->safe_object_iterate(cl); 811 _old_gen->safe_object_iterate(cl); 812 } 813 814 Space* GenCollectedHeap::space_containing(const void* addr) const { 815 Space* res = _young_gen->space_containing(addr); 816 if (res != NULL) { 817 return res; 818 } 819 res = _old_gen->space_containing(addr); 820 assert(res != NULL, "Could not find containing space"); 821 return res; 822 } 823 824 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 825 assert(is_in_reserved(addr), "block_start of address outside of heap"); 826 if (_young_gen->is_in_reserved(addr)) { 827 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 828 return _young_gen->block_start(addr); 829 } 830 831 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 832 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 833 return _old_gen->block_start(addr); 834 } 835 836 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 837 assert(is_in_reserved(addr), "block_size of address outside of heap"); 838 if (_young_gen->is_in_reserved(addr)) { 839 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 840 return _young_gen->block_size(addr); 841 } 842 843 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 844 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 845 return _old_gen->block_size(addr); 846 } 847 848 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 849 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 850 assert(block_start(addr) == addr, "addr must be a block start"); 851 if (_young_gen->is_in_reserved(addr)) { 852 return _young_gen->block_is_obj(addr); 853 } 854 855 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 856 return _old_gen->block_is_obj(addr); 857 } 858 859 bool GenCollectedHeap::supports_tlab_allocation() const { 860 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 861 return _young_gen->supports_tlab_allocation(); 862 } 863 864 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 865 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 866 if (_young_gen->supports_tlab_allocation()) { 867 return _young_gen->tlab_capacity(); 868 } 869 return 0; 870 } 871 872 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 873 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 874 if (_young_gen->supports_tlab_allocation()) { 875 return _young_gen->tlab_used(); 876 } 877 return 0; 878 } 879 880 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 881 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 882 if (_young_gen->supports_tlab_allocation()) { 883 return _young_gen->unsafe_max_tlab_alloc(); 884 } 885 return 0; 886 } 887 888 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 889 bool gc_overhead_limit_was_exceeded; 890 return gen_policy()->mem_allocate_work(size /* size */, 891 true /* is_tlab */, 892 &gc_overhead_limit_was_exceeded); 893 } 894 895 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 896 // from the list headed by "*prev_ptr". 897 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 898 bool first = true; 899 size_t min_size = 0; // "first" makes this conceptually infinite. 900 ScratchBlock **smallest_ptr, *smallest; 901 ScratchBlock *cur = *prev_ptr; 902 while (cur) { 903 assert(*prev_ptr == cur, "just checking"); 904 if (first || cur->num_words < min_size) { 905 smallest_ptr = prev_ptr; 906 smallest = cur; 907 min_size = smallest->num_words; 908 first = false; 909 } 910 prev_ptr = &cur->next; 911 cur = cur->next; 912 } 913 smallest = *smallest_ptr; 914 *smallest_ptr = smallest->next; 915 return smallest; 916 } 917 918 // Sort the scratch block list headed by res into decreasing size order, 919 // and set "res" to the result. 920 static void sort_scratch_list(ScratchBlock*& list) { 921 ScratchBlock* sorted = NULL; 922 ScratchBlock* unsorted = list; 923 while (unsorted) { 924 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 925 smallest->next = sorted; 926 sorted = smallest; 927 } 928 list = sorted; 929 } 930 931 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 932 size_t max_alloc_words) { 933 ScratchBlock* res = NULL; 934 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 935 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 936 sort_scratch_list(res); 937 return res; 938 } 939 940 void GenCollectedHeap::release_scratch() { 941 _young_gen->reset_scratch(); 942 _old_gen->reset_scratch(); 943 } 944 945 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 946 void do_generation(Generation* gen) { 947 gen->prepare_for_verify(); 948 } 949 }; 950 951 void GenCollectedHeap::prepare_for_verify() { 952 ensure_parsability(false); // no need to retire TLABs 953 GenPrepareForVerifyClosure blk; 954 generation_iterate(&blk, false); 955 } 956 957 void GenCollectedHeap::generation_iterate(GenClosure* cl, 958 bool old_to_young) { 959 if (old_to_young) { 960 cl->do_generation(_old_gen); 961 cl->do_generation(_young_gen); 962 } else { 963 cl->do_generation(_young_gen); 964 cl->do_generation(_old_gen); 965 } 966 } 967 968 bool GenCollectedHeap::is_maximal_no_gc() const { 969 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 970 } 971 972 void GenCollectedHeap::save_marks() { 973 _young_gen->save_marks(); 974 _old_gen->save_marks(); 975 } 976 977 GenCollectedHeap* GenCollectedHeap::heap() { 978 CollectedHeap* heap = Universe::heap(); 979 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 980 assert(heap->kind() == CollectedHeap::SerialHeap || 981 heap->kind() == CollectedHeap::CMSHeap, "Not a GenCollectedHeap"); 982 return (GenCollectedHeap*) heap; 983 } 984 985 void GenCollectedHeap::prepare_for_compaction() { 986 // Start by compacting into same gen. 987 CompactPoint cp(_old_gen); 988 _old_gen->prepare_for_compaction(&cp); 989 _young_gen->prepare_for_compaction(&cp); 990 } 991 992 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 993 log_debug(gc, verify)("%s", _old_gen->name()); 994 _old_gen->verify(); 995 996 log_debug(gc, verify)("%s", _old_gen->name()); 997 _young_gen->verify(); 998 999 log_debug(gc, verify)("RemSet"); 1000 rem_set()->verify(); 1001 } 1002 1003 void GenCollectedHeap::print_on(outputStream* st) const { 1004 _young_gen->print_on(st); 1005 _old_gen->print_on(st); 1006 MetaspaceAux::print_on(st); 1007 } 1008 1009 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1010 } 1011 1012 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1013 } 1014 1015 void GenCollectedHeap::print_tracing_info() const { 1016 if (log_is_enabled(Debug, gc, heap, exit)) { 1017 LogStreamHandle(Debug, gc, heap, exit) lsh; 1018 _young_gen->print_summary_info_on(&lsh); 1019 _old_gen->print_summary_info_on(&lsh); 1020 } 1021 } 1022 1023 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1024 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1025 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1026 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1027 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1028 } 1029 1030 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1031 private: 1032 bool _full; 1033 public: 1034 void do_generation(Generation* gen) { 1035 gen->gc_prologue(_full); 1036 } 1037 GenGCPrologueClosure(bool full) : _full(full) {}; 1038 }; 1039 1040 void GenCollectedHeap::gc_prologue(bool full) { 1041 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1042 1043 // Fill TLAB's and such 1044 CollectedHeap::accumulate_statistics_all_tlabs(); 1045 ensure_parsability(true); // retire TLABs 1046 1047 // Walk generations 1048 GenGCPrologueClosure blk(full); 1049 generation_iterate(&blk, false); // not old-to-young. 1050 }; 1051 1052 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1053 private: 1054 bool _full; 1055 public: 1056 void do_generation(Generation* gen) { 1057 gen->gc_epilogue(_full); 1058 } 1059 GenGCEpilogueClosure(bool full) : _full(full) {}; 1060 }; 1061 1062 void GenCollectedHeap::gc_epilogue(bool full) { 1063 #if COMPILER2_OR_JVMCI 1064 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1065 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1066 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1067 #endif // COMPILER2_OR_JVMCI 1068 1069 resize_all_tlabs(); 1070 1071 GenGCEpilogueClosure blk(full); 1072 generation_iterate(&blk, false); // not old-to-young. 1073 1074 if (!CleanChunkPoolAsync) { 1075 Chunk::clean_chunk_pool(); 1076 } 1077 1078 MetaspaceCounters::update_performance_counters(); 1079 CompressedClassSpaceCounters::update_performance_counters(); 1080 }; 1081 1082 #ifndef PRODUCT 1083 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1084 private: 1085 public: 1086 void do_generation(Generation* gen) { 1087 gen->record_spaces_top(); 1088 } 1089 }; 1090 1091 void GenCollectedHeap::record_gen_tops_before_GC() { 1092 if (ZapUnusedHeapArea) { 1093 GenGCSaveTopsBeforeGCClosure blk; 1094 generation_iterate(&blk, false); // not old-to-young. 1095 } 1096 } 1097 #endif // not PRODUCT 1098 1099 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1100 public: 1101 void do_generation(Generation* gen) { 1102 gen->ensure_parsability(); 1103 } 1104 }; 1105 1106 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1107 CollectedHeap::ensure_parsability(retire_tlabs); 1108 GenEnsureParsabilityClosure ep_cl; 1109 generation_iterate(&ep_cl, false); 1110 } 1111 1112 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1113 oop obj, 1114 size_t obj_size) { 1115 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1116 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1117 HeapWord* result = NULL; 1118 1119 result = old_gen->expand_and_allocate(obj_size, false); 1120 1121 if (result != NULL) { 1122 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1123 } 1124 return oop(result); 1125 } 1126 1127 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1128 jlong _time; // in ms 1129 jlong _now; // in ms 1130 1131 public: 1132 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1133 1134 jlong time() { return _time; } 1135 1136 void do_generation(Generation* gen) { 1137 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1138 } 1139 }; 1140 1141 jlong GenCollectedHeap::millis_since_last_gc() { 1142 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1143 // provided the underlying platform provides such a time source 1144 // (and it is bug free). So we still have to guard against getting 1145 // back a time later than 'now'. 1146 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1147 GenTimeOfLastGCClosure tolgc_cl(now); 1148 // iterate over generations getting the oldest 1149 // time that a generation was collected 1150 generation_iterate(&tolgc_cl, false); 1151 1152 jlong retVal = now - tolgc_cl.time(); 1153 if (retVal < 0) { 1154 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 1155 ". returning zero instead.", retVal); 1156 return 0; 1157 } 1158 return retVal; 1159 }