1 /* 2 * Copyright (c) 2000, 2019, 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/classLoaderDataGraph.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/stringTable.hpp" 30 #include "classfile/systemDictionary.hpp" 31 #include "classfile/vmSymbols.hpp" 32 #include "code/codeCache.hpp" 33 #include "code/icBuffer.hpp" 34 #include "gc/serial/defNewGeneration.hpp" 35 #include "gc/shared/adaptiveSizePolicy.hpp" 36 #include "gc/shared/cardTableBarrierSet.hpp" 37 #include "gc/shared/cardTableRS.hpp" 38 #include "gc/shared/collectedHeap.inline.hpp" 39 #include "gc/shared/collectorCounters.hpp" 40 #include "gc/shared/gcId.hpp" 41 #include "gc/shared/gcLocker.hpp" 42 #include "gc/shared/gcPolicyCounters.hpp" 43 #include "gc/shared/gcTrace.hpp" 44 #include "gc/shared/gcTraceTime.inline.hpp" 45 #include "gc/shared/genArguments.hpp" 46 #include "gc/shared/gcVMOperations.hpp" 47 #include "gc/shared/genCollectedHeap.hpp" 48 #include "gc/shared/genOopClosures.inline.hpp" 49 #include "gc/shared/generationSpec.hpp" 50 #include "gc/shared/oopStorageParState.inline.hpp" 51 #include "gc/shared/scavengableNMethods.hpp" 52 #include "gc/shared/space.hpp" 53 #include "gc/shared/strongRootsScope.hpp" 54 #include "gc/shared/weakProcessor.hpp" 55 #include "gc/shared/workgroup.hpp" 56 #include "memory/filemap.hpp" 57 #include "memory/metaspaceCounters.hpp" 58 #include "memory/metaspace/metaspaceSizesSnapshot.hpp" 59 #include "memory/resourceArea.hpp" 60 #include "memory/universe.hpp" 61 #include "oops/oop.inline.hpp" 62 #include "runtime/biasedLocking.hpp" 63 #include "runtime/flags/flagSetting.hpp" 64 #include "runtime/handles.hpp" 65 #include "runtime/handles.inline.hpp" 66 #include "runtime/java.hpp" 67 #include "runtime/vmThread.hpp" 68 #include "services/management.hpp" 69 #include "services/memoryService.hpp" 70 #include "utilities/debug.hpp" 71 #include "utilities/formatBuffer.hpp" 72 #include "utilities/macros.hpp" 73 #include "utilities/stack.inline.hpp" 74 #include "utilities/vmError.hpp" 75 #if INCLUDE_JVMCI 76 #include "jvmci/jvmci.hpp" 77 #endif 78 79 GenCollectedHeap::GenCollectedHeap(Generation::Name young, 80 Generation::Name old, 81 const char* policy_counters_name) : 82 CollectedHeap(), 83 _young_gen_spec(new GenerationSpec(young, 84 NewSize, 85 MaxNewSize, 86 GenAlignment)), 87 _old_gen_spec(new GenerationSpec(old, 88 OldSize, 89 MaxOldSize, 90 GenAlignment)), 91 _rem_set(NULL), 92 _soft_ref_gen_policy(), 93 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)), 94 _full_collections_completed(0), 95 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)) { 96 } 97 98 jint GenCollectedHeap::initialize() { 99 // While there are no constraints in the GC code that HeapWordSize 100 // be any particular value, there are multiple other areas in the 101 // system which believe this to be true (e.g. oop->object_size in some 102 // cases incorrectly returns the size in wordSize units rather than 103 // HeapWordSize). 104 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 105 106 // Allocate space for the heap. 107 108 char* heap_address; 109 ReservedSpace heap_rs; 110 111 heap_address = allocate(HeapAlignment, &heap_rs); 112 113 if (!heap_rs.is_reserved()) { 114 vm_shutdown_during_initialization( 115 "Could not reserve enough space for object heap"); 116 return JNI_ENOMEM; 117 } 118 119 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 120 121 _rem_set = create_rem_set(reserved_region()); 122 _rem_set->initialize(); 123 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set); 124 bs->initialize(); 125 BarrierSet::set_barrier_set(bs); 126 127 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false); 128 _young_gen = _young_gen_spec->init(young_rs, rem_set()); 129 heap_rs = heap_rs.last_part(_young_gen_spec->max_size()); 130 131 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false); 132 _old_gen = _old_gen_spec->init(old_rs, rem_set()); 133 clear_incremental_collection_failed(); 134 135 return JNI_OK; 136 } 137 138 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) { 139 return new CardTableRS(reserved_region, false /* scan_concurrently */); 140 } 141 142 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size, 143 size_t init_promo_size, 144 size_t init_survivor_size) { 145 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0; 146 _size_policy = new AdaptiveSizePolicy(init_eden_size, 147 init_promo_size, 148 init_survivor_size, 149 max_gc_pause_sec, 150 GCTimeRatio); 151 } 152 153 char* GenCollectedHeap::allocate(size_t alignment, 154 ReservedSpace* heap_rs){ 155 // Now figure out the total size. 156 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 157 assert(alignment % pageSize == 0, "Must be"); 158 159 // Check for overflow. 160 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size(); 161 if (total_reserved < _young_gen_spec->max_size()) { 162 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 163 "the maximum representable size"); 164 } 165 assert(total_reserved % alignment == 0, 166 "Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 167 SIZE_FORMAT, total_reserved, alignment); 168 169 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 170 171 os::trace_page_sizes("Heap", 172 MinHeapSize, 173 total_reserved, 174 alignment, 175 heap_rs->base(), 176 heap_rs->size()); 177 178 return heap_rs->base(); 179 } 180 181 class GenIsScavengable : public BoolObjectClosure { 182 public: 183 bool do_object_b(oop obj) { 184 return GenCollectedHeap::heap()->is_in_young(obj); 185 } 186 }; 187 188 static GenIsScavengable _is_scavengable; 189 190 void GenCollectedHeap::post_initialize() { 191 CollectedHeap::post_initialize(); 192 ref_processing_init(); 193 194 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 195 196 initialize_size_policy(def_new_gen->eden()->capacity(), 197 _old_gen->capacity(), 198 def_new_gen->from()->capacity()); 199 200 MarkSweep::initialize(); 201 202 ScavengableNMethods::initialize(&_is_scavengable); 203 } 204 205 void GenCollectedHeap::ref_processing_init() { 206 _young_gen->ref_processor_init(); 207 _old_gen->ref_processor_init(); 208 } 209 210 GenerationSpec* GenCollectedHeap::young_gen_spec() const { 211 return _young_gen_spec; 212 } 213 214 GenerationSpec* GenCollectedHeap::old_gen_spec() const { 215 return _old_gen_spec; 216 } 217 218 size_t GenCollectedHeap::capacity() const { 219 return _young_gen->capacity() + _old_gen->capacity(); 220 } 221 222 size_t GenCollectedHeap::used() const { 223 return _young_gen->used() + _old_gen->used(); 224 } 225 226 void GenCollectedHeap::save_used_regions() { 227 _old_gen->save_used_region(); 228 _young_gen->save_used_region(); 229 } 230 231 size_t GenCollectedHeap::max_capacity() const { 232 return _young_gen->max_capacity() + _old_gen->max_capacity(); 233 } 234 235 // Update the _full_collections_completed counter 236 // at the end of a stop-world full GC. 237 unsigned int GenCollectedHeap::update_full_collections_completed() { 238 MonitorLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 239 assert(_full_collections_completed <= _total_full_collections, 240 "Can't complete more collections than were started"); 241 _full_collections_completed = _total_full_collections; 242 ml.notify_all(); 243 return _full_collections_completed; 244 } 245 246 // Update the _full_collections_completed counter, as appropriate, 247 // at the end of a concurrent GC cycle. Note the conditional update 248 // below to allow this method to be called by a concurrent collector 249 // without synchronizing in any manner with the VM thread (which 250 // may already have initiated a STW full collection "concurrently"). 251 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 252 MonitorLocker ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 253 assert((_full_collections_completed <= _total_full_collections) && 254 (count <= _total_full_collections), 255 "Can't complete more collections than were started"); 256 if (count > _full_collections_completed) { 257 _full_collections_completed = count; 258 ml.notify_all(); 259 } 260 return _full_collections_completed; 261 } 262 263 // Return true if any of the following is true: 264 // . the allocation won't fit into the current young gen heap 265 // . gc locker is occupied (jni critical section) 266 // . heap memory is tight -- the most recent previous collection 267 // was a full collection because a partial collection (would 268 // have) failed and is likely to fail again 269 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const { 270 size_t young_capacity = _young_gen->capacity_before_gc(); 271 return (word_size > heap_word_size(young_capacity)) 272 || GCLocker::is_active_and_needs_gc() 273 || incremental_collection_failed(); 274 } 275 276 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) { 277 HeapWord* result = NULL; 278 if (_old_gen->should_allocate(size, is_tlab)) { 279 result = _old_gen->expand_and_allocate(size, is_tlab); 280 } 281 if (result == NULL) { 282 if (_young_gen->should_allocate(size, is_tlab)) { 283 result = _young_gen->expand_and_allocate(size, is_tlab); 284 } 285 } 286 assert(result == NULL || is_in_reserved(result), "result not in heap"); 287 return result; 288 } 289 290 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size, 291 bool is_tlab, 292 bool* gc_overhead_limit_was_exceeded) { 293 // In general gc_overhead_limit_was_exceeded should be false so 294 // set it so here and reset it to true only if the gc time 295 // limit is being exceeded as checked below. 296 *gc_overhead_limit_was_exceeded = false; 297 298 HeapWord* result = NULL; 299 300 // Loop until the allocation is satisfied, or unsatisfied after GC. 301 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) { 302 HandleMark hm; // Discard any handles allocated in each iteration. 303 304 // First allocation attempt is lock-free. 305 Generation *young = _young_gen; 306 assert(young->supports_inline_contig_alloc(), 307 "Otherwise, must do alloc within heap lock"); 308 if (young->should_allocate(size, is_tlab)) { 309 result = young->par_allocate(size, is_tlab); 310 if (result != NULL) { 311 assert(is_in_reserved(result), "result not in heap"); 312 return result; 313 } 314 } 315 uint gc_count_before; // Read inside the Heap_lock locked region. 316 { 317 MutexLocker ml(Heap_lock); 318 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation"); 319 // Note that only large objects get a shot at being 320 // allocated in later generations. 321 bool first_only = !should_try_older_generation_allocation(size); 322 323 result = attempt_allocation(size, is_tlab, first_only); 324 if (result != NULL) { 325 assert(is_in_reserved(result), "result not in heap"); 326 return result; 327 } 328 329 if (GCLocker::is_active_and_needs_gc()) { 330 if (is_tlab) { 331 return NULL; // Caller will retry allocating individual object. 332 } 333 if (!is_maximal_no_gc()) { 334 // Try and expand heap to satisfy request. 335 result = expand_heap_and_allocate(size, is_tlab); 336 // Result could be null if we are out of space. 337 if (result != NULL) { 338 return result; 339 } 340 } 341 342 if (gclocker_stalled_count > GCLockerRetryAllocationCount) { 343 return NULL; // We didn't get to do a GC and we didn't get any memory. 344 } 345 346 // If this thread is not in a jni critical section, we stall 347 // the requestor until the critical section has cleared and 348 // GC allowed. When the critical section clears, a GC is 349 // initiated by the last thread exiting the critical section; so 350 // we retry the allocation sequence from the beginning of the loop, 351 // rather than causing more, now probably unnecessary, GC attempts. 352 JavaThread* jthr = JavaThread::current(); 353 if (!jthr->in_critical()) { 354 MutexUnlocker mul(Heap_lock); 355 // Wait for JNI critical section to be exited 356 GCLocker::stall_until_clear(); 357 gclocker_stalled_count += 1; 358 continue; 359 } else { 360 if (CheckJNICalls) { 361 fatal("Possible deadlock due to allocating while" 362 " in jni critical section"); 363 } 364 return NULL; 365 } 366 } 367 368 // Read the gc count while the heap lock is held. 369 gc_count_before = total_collections(); 370 } 371 372 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before); 373 VMThread::execute(&op); 374 if (op.prologue_succeeded()) { 375 result = op.result(); 376 if (op.gc_locked()) { 377 assert(result == NULL, "must be NULL if gc_locked() is true"); 378 continue; // Retry and/or stall as necessary. 379 } 380 381 // Allocation has failed and a collection 382 // has been done. If the gc time limit was exceeded the 383 // this time, return NULL so that an out-of-memory 384 // will be thrown. Clear gc_overhead_limit_exceeded 385 // so that the overhead exceeded does not persist. 386 387 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded(); 388 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear(); 389 390 if (limit_exceeded && softrefs_clear) { 391 *gc_overhead_limit_was_exceeded = true; 392 size_policy()->set_gc_overhead_limit_exceeded(false); 393 if (op.result() != NULL) { 394 CollectedHeap::fill_with_object(op.result(), size); 395 } 396 return NULL; 397 } 398 assert(result == NULL || is_in_reserved(result), 399 "result not in heap"); 400 return result; 401 } 402 403 // Give a warning if we seem to be looping forever. 404 if ((QueuedAllocationWarningCount > 0) && 405 (try_count % QueuedAllocationWarningCount == 0)) { 406 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times," 407 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : ""); 408 } 409 } 410 } 411 412 #ifndef PRODUCT 413 // Override of memory state checking method in CollectedHeap: 414 // Some collectors (CMS for example) can't have badHeapWordVal written 415 // in the first two words of an object. (For instance , in the case of 416 // CMS these words hold state used to synchronize between certain 417 // (concurrent) GC steps and direct allocating mutators.) 418 // The skip_header_HeapWords() method below, allows us to skip 419 // over the requisite number of HeapWord's. Note that (for 420 // generational collectors) this means that those many words are 421 // skipped in each object, irrespective of the generation in which 422 // that object lives. The resultant loss of precision seems to be 423 // harmless and the pain of avoiding that imprecision appears somewhat 424 // higher than we are prepared to pay for such rudimentary debugging 425 // support. 426 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 427 size_t size) { 428 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 429 // We are asked to check a size in HeapWords, 430 // but the memory is mangled in juint words. 431 juint* start = (juint*) (addr + skip_header_HeapWords()); 432 juint* end = (juint*) (addr + size); 433 for (juint* slot = start; slot < end; slot += 1) { 434 assert(*slot == badHeapWordVal, 435 "Found non badHeapWordValue in pre-allocation check"); 436 } 437 } 438 } 439 #endif 440 441 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 442 bool is_tlab, 443 bool first_only) { 444 HeapWord* res = NULL; 445 446 if (_young_gen->should_allocate(size, is_tlab)) { 447 res = _young_gen->allocate(size, is_tlab); 448 if (res != NULL || first_only) { 449 return res; 450 } 451 } 452 453 if (_old_gen->should_allocate(size, is_tlab)) { 454 res = _old_gen->allocate(size, is_tlab); 455 } 456 457 return res; 458 } 459 460 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 461 bool* gc_overhead_limit_was_exceeded) { 462 return mem_allocate_work(size, 463 false /* is_tlab */, 464 gc_overhead_limit_was_exceeded); 465 } 466 467 bool GenCollectedHeap::must_clear_all_soft_refs() { 468 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || 469 _gc_cause == GCCause::_wb_full_gc; 470 } 471 472 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 473 bool is_tlab, bool run_verification, bool clear_soft_refs, 474 bool restore_marks_for_biased_locking) { 475 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 476 GCTraceTime(Trace, gc, phases) t1(title); 477 TraceCollectorStats tcs(gen->counters()); 478 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause()); 479 480 gen->stat_record()->invocations++; 481 gen->stat_record()->accumulated_time.start(); 482 483 // Must be done anew before each collection because 484 // a previous collection will do mangling and will 485 // change top of some spaces. 486 record_gen_tops_before_GC(); 487 488 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 489 490 if (run_verification && VerifyBeforeGC) { 491 HandleMark hm; // Discard invalid handles created during verification 492 Universe::verify("Before GC"); 493 } 494 COMPILER2_PRESENT(DerivedPointerTable::clear()); 495 496 if (restore_marks_for_biased_locking) { 497 // We perform this mark word preservation work lazily 498 // because it's only at this point that we know whether we 499 // absolutely have to do it; we want to avoid doing it for 500 // scavenge-only collections where it's unnecessary 501 BiasedLocking::preserve_marks(); 502 } 503 504 // Do collection work 505 { 506 // Note on ref discovery: For what appear to be historical reasons, 507 // GCH enables and disabled (by enqueing) refs discovery. 508 // In the future this should be moved into the generation's 509 // collect method so that ref discovery and enqueueing concerns 510 // are local to a generation. The collect method could return 511 // an appropriate indication in the case that notification on 512 // the ref lock was needed. This will make the treatment of 513 // weak refs more uniform (and indeed remove such concerns 514 // from GCH). XXX 515 516 HandleMark hm; // Discard invalid handles created during gc 517 save_marks(); // save marks for all gens 518 // We want to discover references, but not process them yet. 519 // This mode is disabled in process_discovered_references if the 520 // generation does some collection work, or in 521 // enqueue_discovered_references if the generation returns 522 // without doing any work. 523 ReferenceProcessor* rp = gen->ref_processor(); 524 // If the discovery of ("weak") refs in this generation is 525 // atomic wrt other collectors in this configuration, we 526 // are guaranteed to have empty discovered ref lists. 527 if (rp->discovery_is_atomic()) { 528 rp->enable_discovery(); 529 rp->setup_policy(clear_soft_refs); 530 } else { 531 // collect() below will enable discovery as appropriate 532 } 533 gen->collect(full, clear_soft_refs, size, is_tlab); 534 if (!rp->enqueuing_is_done()) { 535 rp->disable_discovery(); 536 } else { 537 rp->set_enqueuing_is_done(false); 538 } 539 rp->verify_no_references_recorded(); 540 } 541 542 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 543 544 gen->stat_record()->accumulated_time.stop(); 545 546 update_gc_stats(gen, full); 547 548 if (run_verification && VerifyAfterGC) { 549 HandleMark hm; // Discard invalid handles created during verification 550 Universe::verify("After GC"); 551 } 552 } 553 554 void GenCollectedHeap::do_collection(bool full, 555 bool clear_all_soft_refs, 556 size_t size, 557 bool is_tlab, 558 GenerationType max_generation) { 559 ResourceMark rm; 560 DEBUG_ONLY(Thread* my_thread = Thread::current();) 561 562 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 563 assert(my_thread->is_VM_thread() || 564 my_thread->is_ConcurrentGC_thread(), 565 "incorrect thread type capability"); 566 assert(Heap_lock->is_locked(), 567 "the requesting thread should have the Heap_lock"); 568 guarantee(!is_gc_active(), "collection is not reentrant"); 569 570 if (GCLocker::check_active_before_gc()) { 571 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 572 } 573 574 const bool do_clear_all_soft_refs = clear_all_soft_refs || 575 soft_ref_policy()->should_clear_all_soft_refs(); 576 577 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy()); 578 579 FlagSetting fl(_is_gc_active, true); 580 581 bool complete = full && (max_generation == OldGen); 582 bool old_collects_young = complete && !ScavengeBeforeFullGC; 583 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 584 585 size_t young_prev_used = _young_gen->used(); 586 size_t old_prev_used = _old_gen->used(); 587 const metaspace::MetaspaceSizesSnapshot prev_meta_sizes; 588 589 bool run_verification = total_collections() >= VerifyGCStartAt; 590 bool prepared_for_verification = false; 591 bool do_full_collection = false; 592 593 if (do_young_collection) { 594 GCIdMark gc_id_mark; 595 GCTraceCPUTime tcpu; 596 GCTraceTime(Info, gc) t("Pause Young", NULL, gc_cause(), true); 597 598 print_heap_before_gc(); 599 600 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 601 prepare_for_verify(); 602 prepared_for_verification = true; 603 } 604 605 gc_prologue(complete); 606 increment_total_collections(complete); 607 608 collect_generation(_young_gen, 609 full, 610 size, 611 is_tlab, 612 run_verification && VerifyGCLevel <= 0, 613 do_clear_all_soft_refs, 614 false); 615 616 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 617 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 618 // Allocation request was met by young GC. 619 size = 0; 620 } 621 622 // Ask if young collection is enough. If so, do the final steps for young collection, 623 // and fallthrough to the end. 624 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation); 625 if (!do_full_collection) { 626 // Adjust generation sizes. 627 _young_gen->compute_new_size(); 628 629 print_heap_change(young_prev_used, old_prev_used); 630 MetaspaceUtils::print_metaspace_change(prev_meta_sizes); 631 632 // Track memory usage and detect low memory after GC finishes 633 MemoryService::track_memory_usage(); 634 635 gc_epilogue(complete); 636 } 637 638 print_heap_after_gc(); 639 640 } else { 641 // No young collection, ask if we need to perform Full collection. 642 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation); 643 } 644 645 if (do_full_collection) { 646 GCIdMark gc_id_mark; 647 GCTraceCPUTime tcpu; 648 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 649 650 print_heap_before_gc(); 651 652 if (!prepared_for_verification && run_verification && 653 VerifyGCLevel <= 1 && VerifyBeforeGC) { 654 prepare_for_verify(); 655 } 656 657 if (!do_young_collection) { 658 gc_prologue(complete); 659 increment_total_collections(complete); 660 } 661 662 // Accounting quirk: total full collections would be incremented when "complete" 663 // is set, by calling increment_total_collections above. However, we also need to 664 // account Full collections that had "complete" unset. 665 if (!complete) { 666 increment_total_full_collections(); 667 } 668 669 collect_generation(_old_gen, 670 full, 671 size, 672 is_tlab, 673 run_verification && VerifyGCLevel <= 1, 674 do_clear_all_soft_refs, 675 true); 676 677 // Adjust generation sizes. 678 _old_gen->compute_new_size(); 679 _young_gen->compute_new_size(); 680 681 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 682 ClassLoaderDataGraph::purge(); 683 DEBUG_ONLY(MetaspaceUtils::verify(false);) 684 // Resize the metaspace capacity after full collections 685 MetaspaceGC::compute_new_size(); 686 update_full_collections_completed(); 687 688 print_heap_change(young_prev_used, old_prev_used); 689 MetaspaceUtils::print_metaspace_change(prev_meta_sizes); 690 691 // Track memory usage and detect low memory after GC finishes 692 MemoryService::track_memory_usage(); 693 694 // Need to tell the epilogue code we are done with Full GC, regardless what was 695 // the initial value for "complete" flag. 696 gc_epilogue(true); 697 698 BiasedLocking::restore_marks(); 699 700 print_heap_after_gc(); 701 } 702 703 #ifdef TRACESPINNING 704 ParallelTaskTerminator::print_termination_counts(); 705 #endif 706 } 707 708 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab, 709 GenCollectedHeap::GenerationType max_gen) const { 710 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab); 711 } 712 713 void GenCollectedHeap::register_nmethod(nmethod* nm) { 714 ScavengableNMethods::register_nmethod(nm); 715 } 716 717 void GenCollectedHeap::unregister_nmethod(nmethod* nm) { 718 ScavengableNMethods::unregister_nmethod(nm); 719 } 720 721 void GenCollectedHeap::verify_nmethod(nmethod* nm) { 722 ScavengableNMethods::verify_nmethod(nm); 723 } 724 725 void GenCollectedHeap::flush_nmethod(nmethod* nm) { 726 // Do nothing. 727 } 728 729 void GenCollectedHeap::prune_scavengable_nmethods() { 730 ScavengableNMethods::prune_nmethods(); 731 } 732 733 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 734 GCCauseSetter x(this, GCCause::_allocation_failure); 735 HeapWord* result = NULL; 736 737 assert(size != 0, "Precondition violated"); 738 if (GCLocker::is_active_and_needs_gc()) { 739 // GC locker is active; instead of a collection we will attempt 740 // to expand the heap, if there's room for expansion. 741 if (!is_maximal_no_gc()) { 742 result = expand_heap_and_allocate(size, is_tlab); 743 } 744 return result; // Could be null if we are out of space. 745 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) { 746 // Do an incremental collection. 747 do_collection(false, // full 748 false, // clear_all_soft_refs 749 size, // size 750 is_tlab, // is_tlab 751 GenCollectedHeap::OldGen); // max_generation 752 } else { 753 log_trace(gc)(" :: Trying full because partial may fail :: "); 754 // Try a full collection; see delta for bug id 6266275 755 // for the original code and why this has been simplified 756 // with from-space allocation criteria modified and 757 // such allocation moved out of the safepoint path. 758 do_collection(true, // full 759 false, // clear_all_soft_refs 760 size, // size 761 is_tlab, // is_tlab 762 GenCollectedHeap::OldGen); // max_generation 763 } 764 765 result = attempt_allocation(size, is_tlab, false /*first_only*/); 766 767 if (result != NULL) { 768 assert(is_in_reserved(result), "result not in heap"); 769 return result; 770 } 771 772 // OK, collection failed, try expansion. 773 result = expand_heap_and_allocate(size, is_tlab); 774 if (result != NULL) { 775 return result; 776 } 777 778 // If we reach this point, we're really out of memory. Try every trick 779 // we can to reclaim memory. Force collection of soft references. Force 780 // a complete compaction of the heap. Any additional methods for finding 781 // free memory should be here, especially if they are expensive. If this 782 // attempt fails, an OOM exception will be thrown. 783 { 784 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted 785 786 do_collection(true, // full 787 true, // clear_all_soft_refs 788 size, // size 789 is_tlab, // is_tlab 790 GenCollectedHeap::OldGen); // max_generation 791 } 792 793 result = attempt_allocation(size, is_tlab, false /* first_only */); 794 if (result != NULL) { 795 assert(is_in_reserved(result), "result not in heap"); 796 return result; 797 } 798 799 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 800 "Flag should have been handled and cleared prior to this point"); 801 802 // What else? We might try synchronous finalization later. If the total 803 // space available is large enough for the allocation, then a more 804 // complete compaction phase than we've tried so far might be 805 // appropriate. 806 return NULL; 807 } 808 809 #ifdef ASSERT 810 class AssertNonScavengableClosure: public OopClosure { 811 public: 812 virtual void do_oop(oop* p) { 813 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 814 "Referent should not be scavengable."); } 815 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 816 }; 817 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 818 #endif 819 820 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 821 ScanningOption so, 822 OopClosure* strong_roots, 823 CLDClosure* strong_cld_closure, 824 CLDClosure* weak_cld_closure, 825 CodeBlobToOopClosure* code_roots) { 826 // General roots. 827 assert(code_roots != NULL, "code root closure should always be set"); 828 // _n_termination for _process_strong_tasks should be set up stream 829 // in a method not running in a GC worker. Otherwise the GC worker 830 // could be trying to change the termination condition while the task 831 // is executing in another GC worker. 832 833 if (_process_strong_tasks->try_claim_task(GCH_PS_ClassLoaderDataGraph_oops_do)) { 834 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 835 } 836 837 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 838 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 839 840 bool is_par = scope->n_threads() > 1; 841 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p); 842 843 if (_process_strong_tasks->try_claim_task(GCH_PS_Universe_oops_do)) { 844 Universe::oops_do(strong_roots); 845 } 846 // Global (strong) JNI handles 847 if (_process_strong_tasks->try_claim_task(GCH_PS_JNIHandles_oops_do)) { 848 JNIHandles::oops_do(strong_roots); 849 } 850 851 if (_process_strong_tasks->try_claim_task(GCH_PS_ObjectSynchronizer_oops_do)) { 852 ObjectSynchronizer::oops_do(strong_roots); 853 } 854 if (_process_strong_tasks->try_claim_task(GCH_PS_Management_oops_do)) { 855 Management::oops_do(strong_roots); 856 } 857 if (_process_strong_tasks->try_claim_task(GCH_PS_jvmti_oops_do)) { 858 JvmtiExport::oops_do(strong_roots); 859 } 860 #if INCLUDE_AOT 861 if (UseAOT && _process_strong_tasks->try_claim_task(GCH_PS_aot_oops_do)) { 862 AOTLoader::oops_do(strong_roots); 863 } 864 #endif 865 if (_process_strong_tasks->try_claim_task(GCH_PS_SystemDictionary_oops_do)) { 866 SystemDictionary::oops_do(strong_roots); 867 } 868 869 if (_process_strong_tasks->try_claim_task(GCH_PS_CodeCache_oops_do)) { 870 if (so & SO_ScavengeCodeCache) { 871 assert(code_roots != NULL, "must supply closure for code cache"); 872 873 // We only visit parts of the CodeCache when scavenging. 874 ScavengableNMethods::nmethods_do(code_roots); 875 } 876 if (so & SO_AllCodeCache) { 877 assert(code_roots != NULL, "must supply closure for code cache"); 878 879 // CMSCollector uses this to do intermediate-strength collections. 880 // We scan the entire code cache, since CodeCache::do_unloading is not called. 881 CodeCache::blobs_do(code_roots); 882 } 883 // Verify that the code cache contents are not subject to 884 // movement by a scavenging collection. 885 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 886 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 887 } 888 } 889 890 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope, 891 OopsInGenClosure* root_closure, 892 OopsInGenClosure* old_gen_closure, 893 CLDClosure* cld_closure) { 894 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations); 895 896 process_roots(scope, SO_ScavengeCodeCache, root_closure, 897 cld_closure, cld_closure, &mark_code_closure); 898 899 if (_process_strong_tasks->try_claim_task(GCH_PS_younger_gens)) { 900 root_closure->reset_generation(); 901 } 902 903 // When collection is parallel, all threads get to cooperate to do 904 // old generation scanning. 905 old_gen_closure->set_generation(_old_gen); 906 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); 907 old_gen_closure->reset_generation(); 908 909 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 910 } 911 912 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope, 913 bool is_adjust_phase, 914 ScanningOption so, 915 bool only_strong_roots, 916 OopsInGenClosure* root_closure, 917 CLDClosure* cld_closure) { 918 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase); 919 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 920 921 process_roots(scope, so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure); 922 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 923 } 924 925 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 926 WeakProcessor::oops_do(root_closure); 927 _young_gen->ref_processor()->weak_oops_do(root_closure); 928 _old_gen->ref_processor()->weak_oops_do(root_closure); 929 } 930 931 bool GenCollectedHeap::no_allocs_since_save_marks() { 932 return _young_gen->no_allocs_since_save_marks() && 933 _old_gen->no_allocs_since_save_marks(); 934 } 935 936 bool GenCollectedHeap::supports_inline_contig_alloc() const { 937 return _young_gen->supports_inline_contig_alloc(); 938 } 939 940 HeapWord* volatile* GenCollectedHeap::top_addr() const { 941 return _young_gen->top_addr(); 942 } 943 944 HeapWord** GenCollectedHeap::end_addr() const { 945 return _young_gen->end_addr(); 946 } 947 948 // public collection interfaces 949 950 void GenCollectedHeap::collect(GCCause::Cause cause) { 951 if (cause == GCCause::_wb_young_gc) { 952 // Young collection for the WhiteBox API. 953 collect(cause, YoungGen); 954 } else { 955 #ifdef ASSERT 956 if (cause == GCCause::_scavenge_alot) { 957 // Young collection only. 958 collect(cause, YoungGen); 959 } else { 960 // Stop-the-world full collection. 961 collect(cause, OldGen); 962 } 963 #else 964 // Stop-the-world full collection. 965 collect(cause, OldGen); 966 #endif 967 } 968 } 969 970 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 971 // The caller doesn't have the Heap_lock 972 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 973 MutexLocker ml(Heap_lock); 974 collect_locked(cause, max_generation); 975 } 976 977 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 978 // The caller has the Heap_lock 979 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 980 collect_locked(cause, OldGen); 981 } 982 983 // this is the private collection interface 984 // The Heap_lock is expected to be held on entry. 985 986 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 987 // Read the GC count while holding the Heap_lock 988 unsigned int gc_count_before = total_collections(); 989 unsigned int full_gc_count_before = total_full_collections(); 990 { 991 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 992 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 993 cause, max_generation); 994 VMThread::execute(&op); 995 } 996 } 997 998 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 999 do_full_collection(clear_all_soft_refs, OldGen); 1000 } 1001 1002 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 1003 GenerationType last_generation) { 1004 GenerationType local_last_generation; 1005 if (!incremental_collection_will_fail(false /* don't consult_young */) && 1006 gc_cause() == GCCause::_gc_locker) { 1007 local_last_generation = YoungGen; 1008 } else { 1009 local_last_generation = last_generation; 1010 } 1011 1012 do_collection(true, // full 1013 clear_all_soft_refs, // clear_all_soft_refs 1014 0, // size 1015 false, // is_tlab 1016 local_last_generation); // last_generation 1017 // Hack XXX FIX ME !!! 1018 // A scavenge may not have been attempted, or may have 1019 // been attempted and failed, because the old gen was too full 1020 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 1021 incremental_collection_will_fail(false /* don't consult_young */)) { 1022 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 1023 // This time allow the old gen to be collected as well 1024 do_collection(true, // full 1025 clear_all_soft_refs, // clear_all_soft_refs 1026 0, // size 1027 false, // is_tlab 1028 OldGen); // last_generation 1029 } 1030 } 1031 1032 bool GenCollectedHeap::is_in_young(oop p) { 1033 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 1034 assert(result == _young_gen->is_in_reserved(p), 1035 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 1036 return result; 1037 } 1038 1039 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1040 bool GenCollectedHeap::is_in(const void* p) const { 1041 return _young_gen->is_in(p) || _old_gen->is_in(p); 1042 } 1043 1044 #ifdef ASSERT 1045 // Don't implement this by using is_in_young(). This method is used 1046 // in some cases to check that is_in_young() is correct. 1047 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 1048 assert(is_in_reserved(p) || p == NULL, 1049 "Does not work if address is non-null and outside of the heap"); 1050 return p < _young_gen->reserved().end() && p != NULL; 1051 } 1052 #endif 1053 1054 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) { 1055 _young_gen->oop_iterate(cl); 1056 _old_gen->oop_iterate(cl); 1057 } 1058 1059 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 1060 _young_gen->object_iterate(cl); 1061 _old_gen->object_iterate(cl); 1062 } 1063 1064 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 1065 _young_gen->safe_object_iterate(cl); 1066 _old_gen->safe_object_iterate(cl); 1067 } 1068 1069 Space* GenCollectedHeap::space_containing(const void* addr) const { 1070 Space* res = _young_gen->space_containing(addr); 1071 if (res != NULL) { 1072 return res; 1073 } 1074 res = _old_gen->space_containing(addr); 1075 assert(res != NULL, "Could not find containing space"); 1076 return res; 1077 } 1078 1079 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 1080 assert(is_in_reserved(addr), "block_start of address outside of heap"); 1081 if (_young_gen->is_in_reserved(addr)) { 1082 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 1083 return _young_gen->block_start(addr); 1084 } 1085 1086 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1087 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 1088 return _old_gen->block_start(addr); 1089 } 1090 1091 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 1092 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 1093 assert(block_start(addr) == addr, "addr must be a block start"); 1094 if (_young_gen->is_in_reserved(addr)) { 1095 return _young_gen->block_is_obj(addr); 1096 } 1097 1098 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1099 return _old_gen->block_is_obj(addr); 1100 } 1101 1102 bool GenCollectedHeap::supports_tlab_allocation() const { 1103 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1104 return _young_gen->supports_tlab_allocation(); 1105 } 1106 1107 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 1108 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1109 if (_young_gen->supports_tlab_allocation()) { 1110 return _young_gen->tlab_capacity(); 1111 } 1112 return 0; 1113 } 1114 1115 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 1116 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1117 if (_young_gen->supports_tlab_allocation()) { 1118 return _young_gen->tlab_used(); 1119 } 1120 return 0; 1121 } 1122 1123 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 1124 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1125 if (_young_gen->supports_tlab_allocation()) { 1126 return _young_gen->unsafe_max_tlab_alloc(); 1127 } 1128 return 0; 1129 } 1130 1131 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size, 1132 size_t requested_size, 1133 size_t* actual_size) { 1134 bool gc_overhead_limit_was_exceeded; 1135 HeapWord* result = mem_allocate_work(requested_size /* size */, 1136 true /* is_tlab */, 1137 &gc_overhead_limit_was_exceeded); 1138 if (result != NULL) { 1139 *actual_size = requested_size; 1140 } 1141 1142 return result; 1143 } 1144 1145 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1146 // from the list headed by "*prev_ptr". 1147 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1148 bool first = true; 1149 size_t min_size = 0; // "first" makes this conceptually infinite. 1150 ScratchBlock **smallest_ptr, *smallest; 1151 ScratchBlock *cur = *prev_ptr; 1152 while (cur) { 1153 assert(*prev_ptr == cur, "just checking"); 1154 if (first || cur->num_words < min_size) { 1155 smallest_ptr = prev_ptr; 1156 smallest = cur; 1157 min_size = smallest->num_words; 1158 first = false; 1159 } 1160 prev_ptr = &cur->next; 1161 cur = cur->next; 1162 } 1163 smallest = *smallest_ptr; 1164 *smallest_ptr = smallest->next; 1165 return smallest; 1166 } 1167 1168 // Sort the scratch block list headed by res into decreasing size order, 1169 // and set "res" to the result. 1170 static void sort_scratch_list(ScratchBlock*& list) { 1171 ScratchBlock* sorted = NULL; 1172 ScratchBlock* unsorted = list; 1173 while (unsorted) { 1174 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1175 smallest->next = sorted; 1176 sorted = smallest; 1177 } 1178 list = sorted; 1179 } 1180 1181 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1182 size_t max_alloc_words) { 1183 ScratchBlock* res = NULL; 1184 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1185 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1186 sort_scratch_list(res); 1187 return res; 1188 } 1189 1190 void GenCollectedHeap::release_scratch() { 1191 _young_gen->reset_scratch(); 1192 _old_gen->reset_scratch(); 1193 } 1194 1195 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1196 void do_generation(Generation* gen) { 1197 gen->prepare_for_verify(); 1198 } 1199 }; 1200 1201 void GenCollectedHeap::prepare_for_verify() { 1202 ensure_parsability(false); // no need to retire TLABs 1203 GenPrepareForVerifyClosure blk; 1204 generation_iterate(&blk, false); 1205 } 1206 1207 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1208 bool old_to_young) { 1209 if (old_to_young) { 1210 cl->do_generation(_old_gen); 1211 cl->do_generation(_young_gen); 1212 } else { 1213 cl->do_generation(_young_gen); 1214 cl->do_generation(_old_gen); 1215 } 1216 } 1217 1218 bool GenCollectedHeap::is_maximal_no_gc() const { 1219 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1220 } 1221 1222 void GenCollectedHeap::save_marks() { 1223 _young_gen->save_marks(); 1224 _old_gen->save_marks(); 1225 } 1226 1227 GenCollectedHeap* GenCollectedHeap::heap() { 1228 CollectedHeap* heap = Universe::heap(); 1229 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1230 assert(heap->kind() == CollectedHeap::Serial || 1231 heap->kind() == CollectedHeap::CMS, "Invalid name"); 1232 return (GenCollectedHeap*) heap; 1233 } 1234 1235 #if INCLUDE_SERIALGC 1236 void GenCollectedHeap::prepare_for_compaction() { 1237 // Start by compacting into same gen. 1238 CompactPoint cp(_old_gen); 1239 _old_gen->prepare_for_compaction(&cp); 1240 _young_gen->prepare_for_compaction(&cp); 1241 } 1242 #endif // INCLUDE_SERIALGC 1243 1244 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1245 log_debug(gc, verify)("%s", _old_gen->name()); 1246 _old_gen->verify(); 1247 1248 log_debug(gc, verify)("%s", _old_gen->name()); 1249 _young_gen->verify(); 1250 1251 log_debug(gc, verify)("RemSet"); 1252 rem_set()->verify(); 1253 } 1254 1255 void GenCollectedHeap::print_on(outputStream* st) const { 1256 _young_gen->print_on(st); 1257 _old_gen->print_on(st); 1258 MetaspaceUtils::print_on(st); 1259 } 1260 1261 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1262 } 1263 1264 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1265 } 1266 1267 void GenCollectedHeap::print_tracing_info() const { 1268 if (log_is_enabled(Debug, gc, heap, exit)) { 1269 LogStreamHandle(Debug, gc, heap, exit) lsh; 1270 _young_gen->print_summary_info_on(&lsh); 1271 _old_gen->print_summary_info_on(&lsh); 1272 } 1273 } 1274 1275 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1276 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1277 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1278 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1279 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1280 } 1281 1282 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1283 private: 1284 bool _full; 1285 public: 1286 void do_generation(Generation* gen) { 1287 gen->gc_prologue(_full); 1288 } 1289 GenGCPrologueClosure(bool full) : _full(full) {}; 1290 }; 1291 1292 void GenCollectedHeap::gc_prologue(bool full) { 1293 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1294 1295 // Fill TLAB's and such 1296 ensure_parsability(true); // retire TLABs 1297 1298 // Walk generations 1299 GenGCPrologueClosure blk(full); 1300 generation_iterate(&blk, false); // not old-to-young. 1301 }; 1302 1303 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1304 private: 1305 bool _full; 1306 public: 1307 void do_generation(Generation* gen) { 1308 gen->gc_epilogue(_full); 1309 } 1310 GenGCEpilogueClosure(bool full) : _full(full) {}; 1311 }; 1312 1313 void GenCollectedHeap::gc_epilogue(bool full) { 1314 #if COMPILER2_OR_JVMCI 1315 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1316 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1317 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1318 #endif // COMPILER2_OR_JVMCI 1319 1320 resize_all_tlabs(); 1321 1322 GenGCEpilogueClosure blk(full); 1323 generation_iterate(&blk, false); // not old-to-young. 1324 1325 if (!CleanChunkPoolAsync) { 1326 Chunk::clean_chunk_pool(); 1327 } 1328 1329 MetaspaceCounters::update_performance_counters(); 1330 CompressedClassSpaceCounters::update_performance_counters(); 1331 }; 1332 1333 #ifndef PRODUCT 1334 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1335 private: 1336 public: 1337 void do_generation(Generation* gen) { 1338 gen->record_spaces_top(); 1339 } 1340 }; 1341 1342 void GenCollectedHeap::record_gen_tops_before_GC() { 1343 if (ZapUnusedHeapArea) { 1344 GenGCSaveTopsBeforeGCClosure blk; 1345 generation_iterate(&blk, false); // not old-to-young. 1346 } 1347 } 1348 #endif // not PRODUCT 1349 1350 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1351 public: 1352 void do_generation(Generation* gen) { 1353 gen->ensure_parsability(); 1354 } 1355 }; 1356 1357 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1358 CollectedHeap::ensure_parsability(retire_tlabs); 1359 GenEnsureParsabilityClosure ep_cl; 1360 generation_iterate(&ep_cl, false); 1361 } 1362 1363 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1364 oop obj, 1365 size_t obj_size) { 1366 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1367 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1368 HeapWord* result = NULL; 1369 1370 result = old_gen->expand_and_allocate(obj_size, false); 1371 1372 if (result != NULL) { 1373 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1374 } 1375 return oop(result); 1376 } 1377 1378 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1379 jlong _time; // in ms 1380 jlong _now; // in ms 1381 1382 public: 1383 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1384 1385 jlong time() { return _time; } 1386 1387 void do_generation(Generation* gen) { 1388 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1389 } 1390 }; 1391 1392 jlong GenCollectedHeap::millis_since_last_gc() { 1393 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1394 // provided the underlying platform provides such a time source 1395 // (and it is bug free). So we still have to guard against getting 1396 // back a time later than 'now'. 1397 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1398 GenTimeOfLastGCClosure tolgc_cl(now); 1399 // iterate over generations getting the oldest 1400 // time that a generation was collected 1401 generation_iterate(&tolgc_cl, false); 1402 1403 jlong retVal = now - tolgc_cl.time(); 1404 if (retVal < 0) { 1405 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 1406 ". returning zero instead.", retVal); 1407 return 0; 1408 } 1409 return retVal; 1410 }