1 /* 2 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "aot/aotLoader.hpp" 27 #include "classfile/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/gcVMOperations.hpp" 46 #include "gc/shared/genCollectedHeap.hpp" 47 #include "gc/shared/genOopClosures.inline.hpp" 48 #include "gc/shared/generationSpec.hpp" 49 #include "gc/shared/oopStorageParState.inline.hpp" 50 #include "gc/shared/space.hpp" 51 #include "gc/shared/strongRootsScope.hpp" 52 #include "gc/shared/weakProcessor.hpp" 53 #include "gc/shared/workgroup.hpp" 54 #include "memory/filemap.hpp" 55 #include "memory/metaspaceCounters.hpp" 56 #include "memory/resourceArea.hpp" 57 #include "oops/oop.inline.hpp" 58 #include "runtime/biasedLocking.hpp" 59 #include "runtime/flags/flagSetting.hpp" 60 #include "runtime/handles.hpp" 61 #include "runtime/handles.inline.hpp" 62 #include "runtime/java.hpp" 63 #include "runtime/vmThread.hpp" 64 #include "services/management.hpp" 65 #include "services/memoryService.hpp" 66 #include "utilities/debug.hpp" 67 #include "utilities/formatBuffer.hpp" 68 #include "utilities/macros.hpp" 69 #include "utilities/stack.inline.hpp" 70 #include "utilities/vmError.hpp" 71 72 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy, 73 Generation::Name young, 74 Generation::Name old, 75 const char* policy_counters_name) : 76 CollectedHeap(), 77 _young_gen_spec(new GenerationSpec(young, 78 policy->initial_young_size(), 79 policy->max_young_size(), 80 policy->gen_alignment())), 81 _old_gen_spec(new GenerationSpec(old, 82 policy->initial_old_size(), 83 policy->max_old_size(), 84 policy->gen_alignment())), 85 _rem_set(NULL), 86 _gen_policy(policy), 87 _soft_ref_gen_policy(), 88 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)), 89 _full_collections_completed(0), 90 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)) { 91 } 92 93 jint GenCollectedHeap::initialize() { 94 // While there are no constraints in the GC code that HeapWordSize 95 // be any particular value, there are multiple other areas in the 96 // system which believe this to be true (e.g. oop->object_size in some 97 // cases incorrectly returns the size in wordSize units rather than 98 // HeapWordSize). 99 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 100 101 // Allocate space for the heap. 102 103 char* heap_address; 104 ReservedSpace heap_rs; 105 106 size_t heap_alignment = collector_policy()->heap_alignment(); 107 108 heap_address = allocate(heap_alignment, &heap_rs); 109 110 if (!heap_rs.is_reserved()) { 111 vm_shutdown_during_initialization( 112 "Could not reserve enough space for object heap"); 113 return JNI_ENOMEM; 114 } 115 116 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 117 118 _rem_set = create_rem_set(reserved_region()); 119 _rem_set->initialize(); 120 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set); 121 bs->initialize(); 122 BarrierSet::set_barrier_set(bs); 123 124 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false); 125 _young_gen = _young_gen_spec->init(young_rs, rem_set()); 126 heap_rs = heap_rs.last_part(_young_gen_spec->max_size()); 127 128 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false); 129 _old_gen = _old_gen_spec->init(old_rs, rem_set()); 130 clear_incremental_collection_failed(); 131 132 return JNI_OK; 133 } 134 135 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) { 136 return new CardTableRS(reserved_region, false /* scan_concurrently */); 137 } 138 139 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size, 140 size_t init_promo_size, 141 size_t init_survivor_size) { 142 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0; 143 _size_policy = new AdaptiveSizePolicy(init_eden_size, 144 init_promo_size, 145 init_survivor_size, 146 max_gc_pause_sec, 147 GCTimeRatio); 148 } 149 150 char* GenCollectedHeap::allocate(size_t alignment, 151 ReservedSpace* heap_rs){ 152 // Now figure out the total size. 153 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 154 assert(alignment % pageSize == 0, "Must be"); 155 156 // Check for overflow. 157 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size(); 158 if (total_reserved < _young_gen_spec->max_size()) { 159 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 160 "the maximum representable size"); 161 } 162 assert(total_reserved % alignment == 0, 163 "Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 164 SIZE_FORMAT, total_reserved, alignment); 165 166 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 167 168 os::trace_page_sizes("Heap", 169 collector_policy()->min_heap_byte_size(), 170 total_reserved, 171 alignment, 172 heap_rs->base(), 173 heap_rs->size()); 174 175 return heap_rs->base(); 176 } 177 178 void GenCollectedHeap::post_initialize() { 179 CollectedHeap::post_initialize(); 180 ref_processing_init(); 181 182 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 183 184 initialize_size_policy(def_new_gen->eden()->capacity(), 185 _old_gen->capacity(), 186 def_new_gen->from()->capacity()); 187 188 MarkSweep::initialize(); 189 } 190 191 void GenCollectedHeap::ref_processing_init() { 192 _young_gen->ref_processor_init(); 193 _old_gen->ref_processor_init(); 194 } 195 196 GenerationSpec* GenCollectedHeap::young_gen_spec() const { 197 return _young_gen_spec; 198 } 199 200 GenerationSpec* GenCollectedHeap::old_gen_spec() const { 201 return _old_gen_spec; 202 } 203 204 size_t GenCollectedHeap::capacity() const { 205 return _young_gen->capacity() + _old_gen->capacity(); 206 } 207 208 size_t GenCollectedHeap::used() const { 209 return _young_gen->used() + _old_gen->used(); 210 } 211 212 void GenCollectedHeap::save_used_regions() { 213 _old_gen->save_used_region(); 214 _young_gen->save_used_region(); 215 } 216 217 size_t GenCollectedHeap::max_capacity() const { 218 return _young_gen->max_capacity() + _old_gen->max_capacity(); 219 } 220 221 // Update the _full_collections_completed counter 222 // at the end of a stop-world full GC. 223 unsigned int GenCollectedHeap::update_full_collections_completed() { 224 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 225 assert(_full_collections_completed <= _total_full_collections, 226 "Can't complete more collections than were started"); 227 _full_collections_completed = _total_full_collections; 228 ml.notify_all(); 229 return _full_collections_completed; 230 } 231 232 // Update the _full_collections_completed counter, as appropriate, 233 // at the end of a concurrent GC cycle. Note the conditional update 234 // below to allow this method to be called by a concurrent collector 235 // without synchronizing in any manner with the VM thread (which 236 // may already have initiated a STW full collection "concurrently"). 237 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 238 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 239 assert((_full_collections_completed <= _total_full_collections) && 240 (count <= _total_full_collections), 241 "Can't complete more collections than were started"); 242 if (count > _full_collections_completed) { 243 _full_collections_completed = count; 244 ml.notify_all(); 245 } 246 return _full_collections_completed; 247 } 248 249 // Return true if any of the following is true: 250 // . the allocation won't fit into the current young gen heap 251 // . gc locker is occupied (jni critical section) 252 // . heap memory is tight -- the most recent previous collection 253 // was a full collection because a partial collection (would 254 // have) failed and is likely to fail again 255 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const { 256 size_t young_capacity = _young_gen->capacity_before_gc(); 257 return (word_size > heap_word_size(young_capacity)) 258 || GCLocker::is_active_and_needs_gc() 259 || incremental_collection_failed(); 260 } 261 262 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) { 263 HeapWord* result = NULL; 264 if (_old_gen->should_allocate(size, is_tlab)) { 265 result = _old_gen->expand_and_allocate(size, is_tlab); 266 } 267 if (result == NULL) { 268 if (_young_gen->should_allocate(size, is_tlab)) { 269 result = _young_gen->expand_and_allocate(size, is_tlab); 270 } 271 } 272 assert(result == NULL || is_in_reserved(result), "result not in heap"); 273 return result; 274 } 275 276 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size, 277 bool is_tlab, 278 bool* gc_overhead_limit_was_exceeded) { 279 // In general gc_overhead_limit_was_exceeded should be false so 280 // set it so here and reset it to true only if the gc time 281 // limit is being exceeded as checked below. 282 *gc_overhead_limit_was_exceeded = false; 283 284 HeapWord* result = NULL; 285 286 // Loop until the allocation is satisfied, or unsatisfied after GC. 287 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) { 288 HandleMark hm; // Discard any handles allocated in each iteration. 289 290 // First allocation attempt is lock-free. 291 Generation *young = _young_gen; 292 assert(young->supports_inline_contig_alloc(), 293 "Otherwise, must do alloc within heap lock"); 294 if (young->should_allocate(size, is_tlab)) { 295 result = young->par_allocate(size, is_tlab); 296 if (result != NULL) { 297 assert(is_in_reserved(result), "result not in heap"); 298 return result; 299 } 300 } 301 uint gc_count_before; // Read inside the Heap_lock locked region. 302 { 303 MutexLocker ml(Heap_lock); 304 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation"); 305 // Note that only large objects get a shot at being 306 // allocated in later generations. 307 bool first_only = !should_try_older_generation_allocation(size); 308 309 result = attempt_allocation(size, is_tlab, first_only); 310 if (result != NULL) { 311 assert(is_in_reserved(result), "result not in heap"); 312 return result; 313 } 314 315 if (GCLocker::is_active_and_needs_gc()) { 316 if (is_tlab) { 317 return NULL; // Caller will retry allocating individual object. 318 } 319 if (!is_maximal_no_gc()) { 320 // Try and expand heap to satisfy request. 321 result = expand_heap_and_allocate(size, is_tlab); 322 // Result could be null if we are out of space. 323 if (result != NULL) { 324 return result; 325 } 326 } 327 328 if (gclocker_stalled_count > GCLockerRetryAllocationCount) { 329 return NULL; // We didn't get to do a GC and we didn't get any memory. 330 } 331 332 // If this thread is not in a jni critical section, we stall 333 // the requestor until the critical section has cleared and 334 // GC allowed. When the critical section clears, a GC is 335 // initiated by the last thread exiting the critical section; so 336 // we retry the allocation sequence from the beginning of the loop, 337 // rather than causing more, now probably unnecessary, GC attempts. 338 JavaThread* jthr = JavaThread::current(); 339 if (!jthr->in_critical()) { 340 MutexUnlocker mul(Heap_lock); 341 // Wait for JNI critical section to be exited 342 GCLocker::stall_until_clear(); 343 gclocker_stalled_count += 1; 344 continue; 345 } else { 346 if (CheckJNICalls) { 347 fatal("Possible deadlock due to allocating while" 348 " in jni critical section"); 349 } 350 return NULL; 351 } 352 } 353 354 // Read the gc count while the heap lock is held. 355 gc_count_before = total_collections(); 356 } 357 358 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before); 359 VMThread::execute(&op); 360 if (op.prologue_succeeded()) { 361 result = op.result(); 362 if (op.gc_locked()) { 363 assert(result == NULL, "must be NULL if gc_locked() is true"); 364 continue; // Retry and/or stall as necessary. 365 } 366 367 // Allocation has failed and a collection 368 // has been done. If the gc time limit was exceeded the 369 // this time, return NULL so that an out-of-memory 370 // will be thrown. Clear gc_overhead_limit_exceeded 371 // so that the overhead exceeded does not persist. 372 373 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded(); 374 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear(); 375 376 if (limit_exceeded && softrefs_clear) { 377 *gc_overhead_limit_was_exceeded = true; 378 size_policy()->set_gc_overhead_limit_exceeded(false); 379 if (op.result() != NULL) { 380 CollectedHeap::fill_with_object(op.result(), size); 381 } 382 return NULL; 383 } 384 assert(result == NULL || is_in_reserved(result), 385 "result not in heap"); 386 return result; 387 } 388 389 // Give a warning if we seem to be looping forever. 390 if ((QueuedAllocationWarningCount > 0) && 391 (try_count % QueuedAllocationWarningCount == 0)) { 392 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times," 393 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : ""); 394 } 395 } 396 } 397 398 #ifndef PRODUCT 399 // Override of memory state checking method in CollectedHeap: 400 // Some collectors (CMS for example) can't have badHeapWordVal written 401 // in the first two words of an object. (For instance , in the case of 402 // CMS these words hold state used to synchronize between certain 403 // (concurrent) GC steps and direct allocating mutators.) 404 // The skip_header_HeapWords() method below, allows us to skip 405 // over the requisite number of HeapWord's. Note that (for 406 // generational collectors) this means that those many words are 407 // skipped in each object, irrespective of the generation in which 408 // that object lives. The resultant loss of precision seems to be 409 // harmless and the pain of avoiding that imprecision appears somewhat 410 // higher than we are prepared to pay for such rudimentary debugging 411 // support. 412 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 413 size_t size) { 414 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 415 // We are asked to check a size in HeapWords, 416 // but the memory is mangled in juint words. 417 juint* start = (juint*) (addr + skip_header_HeapWords()); 418 juint* end = (juint*) (addr + size); 419 for (juint* slot = start; slot < end; slot += 1) { 420 assert(*slot == badHeapWordVal, 421 "Found non badHeapWordValue in pre-allocation check"); 422 } 423 } 424 } 425 #endif 426 427 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 428 bool is_tlab, 429 bool first_only) { 430 HeapWord* res = NULL; 431 432 if (_young_gen->should_allocate(size, is_tlab)) { 433 res = _young_gen->allocate(size, is_tlab); 434 if (res != NULL || first_only) { 435 return res; 436 } 437 } 438 439 if (_old_gen->should_allocate(size, is_tlab)) { 440 res = _old_gen->allocate(size, is_tlab); 441 } 442 443 return res; 444 } 445 446 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 447 bool* gc_overhead_limit_was_exceeded) { 448 return mem_allocate_work(size, 449 false /* is_tlab */, 450 gc_overhead_limit_was_exceeded); 451 } 452 453 bool GenCollectedHeap::must_clear_all_soft_refs() { 454 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || 455 _gc_cause == GCCause::_wb_full_gc; 456 } 457 458 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 459 bool is_tlab, bool run_verification, bool clear_soft_refs, 460 bool restore_marks_for_biased_locking) { 461 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 462 GCTraceTime(Trace, gc, phases) t1(title); 463 TraceCollectorStats tcs(gen->counters()); 464 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause()); 465 466 gen->stat_record()->invocations++; 467 gen->stat_record()->accumulated_time.start(); 468 469 // Must be done anew before each collection because 470 // a previous collection will do mangling and will 471 // change top of some spaces. 472 record_gen_tops_before_GC(); 473 474 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 475 476 if (run_verification && VerifyBeforeGC) { 477 HandleMark hm; // Discard invalid handles created during verification 478 Universe::verify("Before GC"); 479 } 480 COMPILER2_PRESENT(DerivedPointerTable::clear()); 481 482 if (restore_marks_for_biased_locking) { 483 // We perform this mark word preservation work lazily 484 // because it's only at this point that we know whether we 485 // absolutely have to do it; we want to avoid doing it for 486 // scavenge-only collections where it's unnecessary 487 BiasedLocking::preserve_marks(); 488 } 489 490 // Do collection work 491 { 492 // Note on ref discovery: For what appear to be historical reasons, 493 // GCH enables and disabled (by enqueing) refs discovery. 494 // In the future this should be moved into the generation's 495 // collect method so that ref discovery and enqueueing concerns 496 // are local to a generation. The collect method could return 497 // an appropriate indication in the case that notification on 498 // the ref lock was needed. This will make the treatment of 499 // weak refs more uniform (and indeed remove such concerns 500 // from GCH). XXX 501 502 HandleMark hm; // Discard invalid handles created during gc 503 save_marks(); // save marks for all gens 504 // We want to discover references, but not process them yet. 505 // This mode is disabled in process_discovered_references if the 506 // generation does some collection work, or in 507 // enqueue_discovered_references if the generation returns 508 // without doing any work. 509 ReferenceProcessor* rp = gen->ref_processor(); 510 // If the discovery of ("weak") refs in this generation is 511 // atomic wrt other collectors in this configuration, we 512 // are guaranteed to have empty discovered ref lists. 513 if (rp->discovery_is_atomic()) { 514 rp->enable_discovery(); 515 rp->setup_policy(clear_soft_refs); 516 } else { 517 // collect() below will enable discovery as appropriate 518 } 519 gen->collect(full, clear_soft_refs, size, is_tlab); 520 if (!rp->enqueuing_is_done()) { 521 rp->disable_discovery(); 522 } else { 523 rp->set_enqueuing_is_done(false); 524 } 525 rp->verify_no_references_recorded(); 526 } 527 528 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 529 530 gen->stat_record()->accumulated_time.stop(); 531 532 update_gc_stats(gen, full); 533 534 if (run_verification && VerifyAfterGC) { 535 HandleMark hm; // Discard invalid handles created during verification 536 Universe::verify("After GC"); 537 } 538 } 539 540 void GenCollectedHeap::do_collection(bool full, 541 bool clear_all_soft_refs, 542 size_t size, 543 bool is_tlab, 544 GenerationType max_generation) { 545 ResourceMark rm; 546 DEBUG_ONLY(Thread* my_thread = Thread::current();) 547 548 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 549 assert(my_thread->is_VM_thread() || 550 my_thread->is_ConcurrentGC_thread(), 551 "incorrect thread type capability"); 552 assert(Heap_lock->is_locked(), 553 "the requesting thread should have the Heap_lock"); 554 guarantee(!is_gc_active(), "collection is not reentrant"); 555 556 if (GCLocker::check_active_before_gc()) { 557 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 558 } 559 560 GCIdMark gc_id_mark; 561 562 const bool do_clear_all_soft_refs = clear_all_soft_refs || 563 soft_ref_policy()->should_clear_all_soft_refs(); 564 565 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy()); 566 567 const size_t metadata_prev_used = MetaspaceUtils::used_bytes(); 568 569 print_heap_before_gc(); 570 571 { 572 FlagSetting fl(_is_gc_active, true); 573 574 bool complete = full && (max_generation == OldGen); 575 bool old_collects_young = complete && !ScavengeBeforeFullGC; 576 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 577 578 FormatBuffer<> gc_string("%s", "Pause "); 579 if (do_young_collection) { 580 gc_string.append("Young"); 581 } else { 582 gc_string.append("Full"); 583 } 584 585 GCTraceCPUTime tcpu; 586 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true); 587 588 gc_prologue(complete); 589 increment_total_collections(complete); 590 591 size_t young_prev_used = _young_gen->used(); 592 size_t old_prev_used = _old_gen->used(); 593 594 bool run_verification = total_collections() >= VerifyGCStartAt; 595 596 bool prepared_for_verification = false; 597 bool collected_old = false; 598 599 if (do_young_collection) { 600 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 601 prepare_for_verify(); 602 prepared_for_verification = true; 603 } 604 605 collect_generation(_young_gen, 606 full, 607 size, 608 is_tlab, 609 run_verification && VerifyGCLevel <= 0, 610 do_clear_all_soft_refs, 611 false); 612 613 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 614 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 615 // Allocation request was met by young GC. 616 size = 0; 617 } 618 } 619 620 bool must_restore_marks_for_biased_locking = false; 621 622 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 623 if (!complete) { 624 // The full_collections increment was missed above. 625 increment_total_full_collections(); 626 } 627 628 if (!prepared_for_verification && run_verification && 629 VerifyGCLevel <= 1 && VerifyBeforeGC) { 630 prepare_for_verify(); 631 } 632 633 if (do_young_collection) { 634 // We did a young GC. Need a new GC id for the old GC. 635 GCIdMark gc_id_mark; 636 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 637 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 638 } else { 639 // No young GC done. Use the same GC id as was set up earlier in this method. 640 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 641 } 642 643 must_restore_marks_for_biased_locking = true; 644 collected_old = true; 645 } 646 647 // Update "complete" boolean wrt what actually transpired -- 648 // for instance, a promotion failure could have led to 649 // a whole heap collection. 650 complete = complete || collected_old; 651 652 // Adjust generation sizes. 653 if (collected_old) { 654 _old_gen->compute_new_size(); 655 } 656 _young_gen->compute_new_size(); 657 658 if (complete) { 659 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 660 ClassLoaderDataGraph::purge(); 661 MetaspaceUtils::verify_metrics(); 662 // Resize the metaspace capacity after full collections 663 MetaspaceGC::compute_new_size(); 664 update_full_collections_completed(); 665 } 666 667 print_heap_change(young_prev_used, old_prev_used); 668 MetaspaceUtils::print_metaspace_change(metadata_prev_used); 669 670 // Track memory usage and detect low memory after GC finishes 671 MemoryService::track_memory_usage(); 672 673 gc_epilogue(complete); 674 675 if (must_restore_marks_for_biased_locking) { 676 BiasedLocking::restore_marks(); 677 } 678 } 679 680 print_heap_after_gc(); 681 682 #ifdef TRACESPINNING 683 ParallelTaskTerminator::print_termination_counts(); 684 #endif 685 } 686 687 void GenCollectedHeap::register_nmethod(nmethod* nm) { 688 CodeCache::register_scavenge_root_nmethod(nm); 689 } 690 691 void GenCollectedHeap::verify_nmethod(nmethod* nm) { 692 CodeCache::verify_scavenge_root_nmethod(nm); 693 } 694 695 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 696 GCCauseSetter x(this, GCCause::_allocation_failure); 697 HeapWord* result = NULL; 698 699 assert(size != 0, "Precondition violated"); 700 if (GCLocker::is_active_and_needs_gc()) { 701 // GC locker is active; instead of a collection we will attempt 702 // to expand the heap, if there's room for expansion. 703 if (!is_maximal_no_gc()) { 704 result = expand_heap_and_allocate(size, is_tlab); 705 } 706 return result; // Could be null if we are out of space. 707 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) { 708 // Do an incremental collection. 709 do_collection(false, // full 710 false, // clear_all_soft_refs 711 size, // size 712 is_tlab, // is_tlab 713 GenCollectedHeap::OldGen); // max_generation 714 } else { 715 log_trace(gc)(" :: Trying full because partial may fail :: "); 716 // Try a full collection; see delta for bug id 6266275 717 // for the original code and why this has been simplified 718 // with from-space allocation criteria modified and 719 // such allocation moved out of the safepoint path. 720 do_collection(true, // full 721 false, // clear_all_soft_refs 722 size, // size 723 is_tlab, // is_tlab 724 GenCollectedHeap::OldGen); // max_generation 725 } 726 727 result = attempt_allocation(size, is_tlab, false /*first_only*/); 728 729 if (result != NULL) { 730 assert(is_in_reserved(result), "result not in heap"); 731 return result; 732 } 733 734 // OK, collection failed, try expansion. 735 result = expand_heap_and_allocate(size, is_tlab); 736 if (result != NULL) { 737 return result; 738 } 739 740 // If we reach this point, we're really out of memory. Try every trick 741 // we can to reclaim memory. Force collection of soft references. Force 742 // a complete compaction of the heap. Any additional methods for finding 743 // free memory should be here, especially if they are expensive. If this 744 // attempt fails, an OOM exception will be thrown. 745 { 746 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted 747 748 do_collection(true, // full 749 true, // clear_all_soft_refs 750 size, // size 751 is_tlab, // is_tlab 752 GenCollectedHeap::OldGen); // max_generation 753 } 754 755 result = attempt_allocation(size, is_tlab, false /* first_only */); 756 if (result != NULL) { 757 assert(is_in_reserved(result), "result not in heap"); 758 return result; 759 } 760 761 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 762 "Flag should have been handled and cleared prior to this point"); 763 764 // What else? We might try synchronous finalization later. If the total 765 // space available is large enough for the allocation, then a more 766 // complete compaction phase than we've tried so far might be 767 // appropriate. 768 return NULL; 769 } 770 771 #ifdef ASSERT 772 class AssertNonScavengableClosure: public OopClosure { 773 public: 774 virtual void do_oop(oop* p) { 775 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 776 "Referent should not be scavengable."); } 777 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 778 }; 779 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 780 #endif 781 782 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 783 ScanningOption so, 784 OopClosure* strong_roots, 785 CLDClosure* strong_cld_closure, 786 CLDClosure* weak_cld_closure, 787 CodeBlobToOopClosure* code_roots) { 788 // General roots. 789 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 790 assert(code_roots != NULL, "code root closure should always be set"); 791 // _n_termination for _process_strong_tasks should be set up stream 792 // in a method not running in a GC worker. Otherwise the GC worker 793 // could be trying to change the termination condition while the task 794 // is executing in another GC worker. 795 796 if (_process_strong_tasks->try_claim_task(GCH_PS_ClassLoaderDataGraph_oops_do)) { 797 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 798 } 799 800 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 801 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 802 803 bool is_par = scope->n_threads() > 1; 804 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p); 805 806 if (_process_strong_tasks->try_claim_task(GCH_PS_Universe_oops_do)) { 807 Universe::oops_do(strong_roots); 808 } 809 // Global (strong) JNI handles 810 if (_process_strong_tasks->try_claim_task(GCH_PS_JNIHandles_oops_do)) { 811 JNIHandles::oops_do(strong_roots); 812 } 813 814 if (_process_strong_tasks->try_claim_task(GCH_PS_ObjectSynchronizer_oops_do)) { 815 ObjectSynchronizer::oops_do(strong_roots); 816 } 817 if (_process_strong_tasks->try_claim_task(GCH_PS_Management_oops_do)) { 818 Management::oops_do(strong_roots); 819 } 820 if (_process_strong_tasks->try_claim_task(GCH_PS_jvmti_oops_do)) { 821 JvmtiExport::oops_do(strong_roots); 822 } 823 if (UseAOT && _process_strong_tasks->try_claim_task(GCH_PS_aot_oops_do)) { 824 AOTLoader::oops_do(strong_roots); 825 } 826 827 if (_process_strong_tasks->try_claim_task(GCH_PS_SystemDictionary_oops_do)) { 828 SystemDictionary::oops_do(strong_roots); 829 } 830 831 if (_process_strong_tasks->try_claim_task(GCH_PS_CodeCache_oops_do)) { 832 if (so & SO_ScavengeCodeCache) { 833 assert(code_roots != NULL, "must supply closure for code cache"); 834 835 // We only visit parts of the CodeCache when scavenging. 836 CodeCache::scavenge_root_nmethods_do(code_roots); 837 } 838 if (so & SO_AllCodeCache) { 839 assert(code_roots != NULL, "must supply closure for code cache"); 840 841 // CMSCollector uses this to do intermediate-strength collections. 842 // We scan the entire code cache, since CodeCache::do_unloading is not called. 843 CodeCache::blobs_do(code_roots); 844 } 845 // Verify that the code cache contents are not subject to 846 // movement by a scavenging collection. 847 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 848 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 849 } 850 } 851 852 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope, 853 OopClosure* root_closure, 854 OopStorage::ParState<false, false>* par_state_string) { 855 assert(root_closure != NULL, "Must be set"); 856 // All threads execute the following. A specific chunk of buckets 857 // from the StringTable are the individual tasks. 858 859 // Either we should be single threaded or have a ParState 860 assert((scope->n_threads() <= 1) || par_state_string != NULL, "Parallel but no ParState"); 861 862 if (scope->n_threads() > 1) { 863 StringTable::possibly_parallel_oops_do(par_state_string, root_closure); 864 } else { 865 StringTable::oops_do(root_closure); 866 } 867 } 868 869 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope, 870 OopsInGenClosure* root_closure, 871 OopsInGenClosure* old_gen_closure, 872 CLDClosure* cld_closure, 873 OopStorage::ParState<false, false>* par_state_string) { 874 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations); 875 876 process_roots(scope, SO_ScavengeCodeCache, root_closure, 877 cld_closure, cld_closure, &mark_code_closure); 878 process_string_table_roots(scope, root_closure, par_state_string); 879 880 if (_process_strong_tasks->try_claim_task(GCH_PS_younger_gens)) { 881 root_closure->reset_generation(); 882 } 883 884 // When collection is parallel, all threads get to cooperate to do 885 // old generation scanning. 886 old_gen_closure->set_generation(_old_gen); 887 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); 888 old_gen_closure->reset_generation(); 889 890 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 891 } 892 893 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope, 894 bool is_adjust_phase, 895 ScanningOption so, 896 bool only_strong_roots, 897 OopsInGenClosure* root_closure, 898 CLDClosure* cld_closure, 899 OopStorage::ParState<false, false>* par_state_string) { 900 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase); 901 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 902 903 process_roots(scope, so, root_closure, cld_closure, weak_cld_closure, &mark_code_closure); 904 if (is_adjust_phase) { 905 // We never treat the string table as roots during marking 906 // for the full gc, so we only need to process it during 907 // the adjust phase. 908 process_string_table_roots(scope, root_closure, par_state_string); 909 } 910 911 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 912 } 913 914 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 915 WeakProcessor::oops_do(root_closure); 916 _young_gen->ref_processor()->weak_oops_do(root_closure); 917 _old_gen->ref_processor()->weak_oops_do(root_closure); 918 } 919 920 bool GenCollectedHeap::no_allocs_since_save_marks() { 921 return _young_gen->no_allocs_since_save_marks() && 922 _old_gen->no_allocs_since_save_marks(); 923 } 924 925 bool GenCollectedHeap::supports_inline_contig_alloc() const { 926 return _young_gen->supports_inline_contig_alloc(); 927 } 928 929 HeapWord* volatile* GenCollectedHeap::top_addr() const { 930 return _young_gen->top_addr(); 931 } 932 933 HeapWord** GenCollectedHeap::end_addr() const { 934 return _young_gen->end_addr(); 935 } 936 937 // public collection interfaces 938 939 void GenCollectedHeap::collect(GCCause::Cause cause) { 940 if (cause == GCCause::_wb_young_gc) { 941 // Young collection for the WhiteBox API. 942 collect(cause, YoungGen); 943 } else { 944 #ifdef ASSERT 945 if (cause == GCCause::_scavenge_alot) { 946 // Young collection only. 947 collect(cause, YoungGen); 948 } else { 949 // Stop-the-world full collection. 950 collect(cause, OldGen); 951 } 952 #else 953 // Stop-the-world full collection. 954 collect(cause, OldGen); 955 #endif 956 } 957 } 958 959 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 960 // The caller doesn't have the Heap_lock 961 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 962 MutexLocker ml(Heap_lock); 963 collect_locked(cause, max_generation); 964 } 965 966 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 967 // The caller has the Heap_lock 968 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 969 collect_locked(cause, OldGen); 970 } 971 972 // this is the private collection interface 973 // The Heap_lock is expected to be held on entry. 974 975 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 976 // Read the GC count while holding the Heap_lock 977 unsigned int gc_count_before = total_collections(); 978 unsigned int full_gc_count_before = total_full_collections(); 979 { 980 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 981 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 982 cause, max_generation); 983 VMThread::execute(&op); 984 } 985 } 986 987 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 988 do_full_collection(clear_all_soft_refs, OldGen); 989 } 990 991 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 992 GenerationType last_generation) { 993 GenerationType local_last_generation; 994 if (!incremental_collection_will_fail(false /* don't consult_young */) && 995 gc_cause() == GCCause::_gc_locker) { 996 local_last_generation = YoungGen; 997 } else { 998 local_last_generation = last_generation; 999 } 1000 1001 do_collection(true, // full 1002 clear_all_soft_refs, // clear_all_soft_refs 1003 0, // size 1004 false, // is_tlab 1005 local_last_generation); // last_generation 1006 // Hack XXX FIX ME !!! 1007 // A scavenge may not have been attempted, or may have 1008 // been attempted and failed, because the old gen was too full 1009 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 1010 incremental_collection_will_fail(false /* don't consult_young */)) { 1011 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 1012 // This time allow the old gen to be collected as well 1013 do_collection(true, // full 1014 clear_all_soft_refs, // clear_all_soft_refs 1015 0, // size 1016 false, // is_tlab 1017 OldGen); // last_generation 1018 } 1019 } 1020 1021 bool GenCollectedHeap::is_in_young(oop p) { 1022 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 1023 assert(result == _young_gen->is_in_reserved(p), 1024 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 1025 return result; 1026 } 1027 1028 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1029 bool GenCollectedHeap::is_in(const void* p) const { 1030 return _young_gen->is_in(p) || _old_gen->is_in(p); 1031 } 1032 1033 #ifdef ASSERT 1034 // Don't implement this by using is_in_young(). This method is used 1035 // in some cases to check that is_in_young() is correct. 1036 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 1037 assert(is_in_reserved(p) || p == NULL, 1038 "Does not work if address is non-null and outside of the heap"); 1039 return p < _young_gen->reserved().end() && p != NULL; 1040 } 1041 #endif 1042 1043 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) { 1044 _young_gen->oop_iterate(cl); 1045 _old_gen->oop_iterate(cl); 1046 } 1047 1048 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 1049 _young_gen->object_iterate(cl); 1050 _old_gen->object_iterate(cl); 1051 } 1052 1053 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 1054 _young_gen->safe_object_iterate(cl); 1055 _old_gen->safe_object_iterate(cl); 1056 } 1057 1058 Space* GenCollectedHeap::space_containing(const void* addr) const { 1059 Space* res = _young_gen->space_containing(addr); 1060 if (res != NULL) { 1061 return res; 1062 } 1063 res = _old_gen->space_containing(addr); 1064 assert(res != NULL, "Could not find containing space"); 1065 return res; 1066 } 1067 1068 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 1069 assert(is_in_reserved(addr), "block_start of address outside of heap"); 1070 if (_young_gen->is_in_reserved(addr)) { 1071 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 1072 return _young_gen->block_start(addr); 1073 } 1074 1075 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1076 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 1077 return _old_gen->block_start(addr); 1078 } 1079 1080 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 1081 assert(is_in_reserved(addr), "block_size of address outside of heap"); 1082 if (_young_gen->is_in_reserved(addr)) { 1083 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 1084 return _young_gen->block_size(addr); 1085 } 1086 1087 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1088 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 1089 return _old_gen->block_size(addr); 1090 } 1091 1092 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 1093 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 1094 assert(block_start(addr) == addr, "addr must be a block start"); 1095 if (_young_gen->is_in_reserved(addr)) { 1096 return _young_gen->block_is_obj(addr); 1097 } 1098 1099 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1100 return _old_gen->block_is_obj(addr); 1101 } 1102 1103 bool GenCollectedHeap::supports_tlab_allocation() const { 1104 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1105 return _young_gen->supports_tlab_allocation(); 1106 } 1107 1108 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 1109 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1110 if (_young_gen->supports_tlab_allocation()) { 1111 return _young_gen->tlab_capacity(); 1112 } 1113 return 0; 1114 } 1115 1116 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 1117 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1118 if (_young_gen->supports_tlab_allocation()) { 1119 return _young_gen->tlab_used(); 1120 } 1121 return 0; 1122 } 1123 1124 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 1125 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1126 if (_young_gen->supports_tlab_allocation()) { 1127 return _young_gen->unsafe_max_tlab_alloc(); 1128 } 1129 return 0; 1130 } 1131 1132 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size, 1133 size_t requested_size, 1134 size_t* actual_size) { 1135 bool gc_overhead_limit_was_exceeded; 1136 HeapWord* result = mem_allocate_work(requested_size /* size */, 1137 true /* is_tlab */, 1138 &gc_overhead_limit_was_exceeded); 1139 if (result != NULL) { 1140 *actual_size = requested_size; 1141 } 1142 1143 return result; 1144 } 1145 1146 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1147 // from the list headed by "*prev_ptr". 1148 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1149 bool first = true; 1150 size_t min_size = 0; // "first" makes this conceptually infinite. 1151 ScratchBlock **smallest_ptr, *smallest; 1152 ScratchBlock *cur = *prev_ptr; 1153 while (cur) { 1154 assert(*prev_ptr == cur, "just checking"); 1155 if (first || cur->num_words < min_size) { 1156 smallest_ptr = prev_ptr; 1157 smallest = cur; 1158 min_size = smallest->num_words; 1159 first = false; 1160 } 1161 prev_ptr = &cur->next; 1162 cur = cur->next; 1163 } 1164 smallest = *smallest_ptr; 1165 *smallest_ptr = smallest->next; 1166 return smallest; 1167 } 1168 1169 // Sort the scratch block list headed by res into decreasing size order, 1170 // and set "res" to the result. 1171 static void sort_scratch_list(ScratchBlock*& list) { 1172 ScratchBlock* sorted = NULL; 1173 ScratchBlock* unsorted = list; 1174 while (unsorted) { 1175 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1176 smallest->next = sorted; 1177 sorted = smallest; 1178 } 1179 list = sorted; 1180 } 1181 1182 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1183 size_t max_alloc_words) { 1184 ScratchBlock* res = NULL; 1185 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1186 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1187 sort_scratch_list(res); 1188 return res; 1189 } 1190 1191 void GenCollectedHeap::release_scratch() { 1192 _young_gen->reset_scratch(); 1193 _old_gen->reset_scratch(); 1194 } 1195 1196 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1197 void do_generation(Generation* gen) { 1198 gen->prepare_for_verify(); 1199 } 1200 }; 1201 1202 void GenCollectedHeap::prepare_for_verify() { 1203 ensure_parsability(false); // no need to retire TLABs 1204 GenPrepareForVerifyClosure blk; 1205 generation_iterate(&blk, false); 1206 } 1207 1208 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1209 bool old_to_young) { 1210 if (old_to_young) { 1211 cl->do_generation(_old_gen); 1212 cl->do_generation(_young_gen); 1213 } else { 1214 cl->do_generation(_young_gen); 1215 cl->do_generation(_old_gen); 1216 } 1217 } 1218 1219 bool GenCollectedHeap::is_maximal_no_gc() const { 1220 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1221 } 1222 1223 void GenCollectedHeap::save_marks() { 1224 _young_gen->save_marks(); 1225 _old_gen->save_marks(); 1226 } 1227 1228 GenCollectedHeap* GenCollectedHeap::heap() { 1229 CollectedHeap* heap = Universe::heap(); 1230 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1231 assert(heap->kind() == CollectedHeap::Serial || 1232 heap->kind() == CollectedHeap::CMS, "Invalid name"); 1233 return (GenCollectedHeap*) heap; 1234 } 1235 1236 #if INCLUDE_SERIALGC 1237 void GenCollectedHeap::prepare_for_compaction() { 1238 // Start by compacting into same gen. 1239 CompactPoint cp(_old_gen); 1240 _old_gen->prepare_for_compaction(&cp); 1241 _young_gen->prepare_for_compaction(&cp); 1242 } 1243 #endif // INCLUDE_SERIALGC 1244 1245 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1246 log_debug(gc, verify)("%s", _old_gen->name()); 1247 _old_gen->verify(); 1248 1249 log_debug(gc, verify)("%s", _old_gen->name()); 1250 _young_gen->verify(); 1251 1252 log_debug(gc, verify)("RemSet"); 1253 rem_set()->verify(); 1254 } 1255 1256 void GenCollectedHeap::print_on(outputStream* st) const { 1257 _young_gen->print_on(st); 1258 _old_gen->print_on(st); 1259 MetaspaceUtils::print_on(st); 1260 } 1261 1262 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1263 } 1264 1265 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1266 } 1267 1268 void GenCollectedHeap::print_tracing_info() const { 1269 if (log_is_enabled(Debug, gc, heap, exit)) { 1270 LogStreamHandle(Debug, gc, heap, exit) lsh; 1271 _young_gen->print_summary_info_on(&lsh); 1272 _old_gen->print_summary_info_on(&lsh); 1273 } 1274 } 1275 1276 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1277 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1278 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1279 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1280 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1281 } 1282 1283 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1284 private: 1285 bool _full; 1286 public: 1287 void do_generation(Generation* gen) { 1288 gen->gc_prologue(_full); 1289 } 1290 GenGCPrologueClosure(bool full) : _full(full) {}; 1291 }; 1292 1293 void GenCollectedHeap::gc_prologue(bool full) { 1294 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1295 1296 // Fill TLAB's and such 1297 ensure_parsability(true); // retire TLABs 1298 1299 // Walk generations 1300 GenGCPrologueClosure blk(full); 1301 generation_iterate(&blk, false); // not old-to-young. 1302 }; 1303 1304 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1305 private: 1306 bool _full; 1307 public: 1308 void do_generation(Generation* gen) { 1309 gen->gc_epilogue(_full); 1310 } 1311 GenGCEpilogueClosure(bool full) : _full(full) {}; 1312 }; 1313 1314 void GenCollectedHeap::gc_epilogue(bool full) { 1315 #if COMPILER2_OR_JVMCI 1316 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1317 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1318 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1319 #endif // COMPILER2_OR_JVMCI 1320 1321 resize_all_tlabs(); 1322 1323 GenGCEpilogueClosure blk(full); 1324 generation_iterate(&blk, false); // not old-to-young. 1325 1326 if (!CleanChunkPoolAsync) { 1327 Chunk::clean_chunk_pool(); 1328 } 1329 1330 MetaspaceCounters::update_performance_counters(); 1331 CompressedClassSpaceCounters::update_performance_counters(); 1332 }; 1333 1334 #ifndef PRODUCT 1335 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1336 private: 1337 public: 1338 void do_generation(Generation* gen) { 1339 gen->record_spaces_top(); 1340 } 1341 }; 1342 1343 void GenCollectedHeap::record_gen_tops_before_GC() { 1344 if (ZapUnusedHeapArea) { 1345 GenGCSaveTopsBeforeGCClosure blk; 1346 generation_iterate(&blk, false); // not old-to-young. 1347 } 1348 } 1349 #endif // not PRODUCT 1350 1351 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1352 public: 1353 void do_generation(Generation* gen) { 1354 gen->ensure_parsability(); 1355 } 1356 }; 1357 1358 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1359 CollectedHeap::ensure_parsability(retire_tlabs); 1360 GenEnsureParsabilityClosure ep_cl; 1361 generation_iterate(&ep_cl, false); 1362 } 1363 1364 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1365 oop obj, 1366 size_t obj_size) { 1367 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1368 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1369 HeapWord* result = NULL; 1370 1371 result = old_gen->expand_and_allocate(obj_size, false); 1372 1373 if (result != NULL) { 1374 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1375 } 1376 return oop(result); 1377 } 1378 1379 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1380 jlong _time; // in ms 1381 jlong _now; // in ms 1382 1383 public: 1384 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1385 1386 jlong time() { return _time; } 1387 1388 void do_generation(Generation* gen) { 1389 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1390 } 1391 }; 1392 1393 jlong GenCollectedHeap::millis_since_last_gc() { 1394 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1395 // provided the underlying platform provides such a time source 1396 // (and it is bug free). So we still have to guard against getting 1397 // back a time later than 'now'. 1398 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1399 GenTimeOfLastGCClosure tolgc_cl(now); 1400 // iterate over generations getting the oldest 1401 // time that a generation was collected 1402 generation_iterate(&tolgc_cl, false); 1403 1404 jlong retVal = now - tolgc_cl.time(); 1405 if (retVal < 0) { 1406 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 1407 ". returning zero instead.", retVal); 1408 return 0; 1409 } 1410 return retVal; 1411 }