1 /* 2 * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #include "precompiled.hpp" 26 #include "aot/aotLoader.hpp" 27 #include "classfile/symbolTable.hpp" 28 #include "classfile/stringTable.hpp" 29 #include "classfile/systemDictionary.hpp" 30 #include "classfile/vmSymbols.hpp" 31 #include "code/codeCache.hpp" 32 #include "code/icBuffer.hpp" 33 #include "gc/shared/adaptiveSizePolicy.hpp" 34 #include "gc/shared/cardTableBarrierSet.hpp" 35 #include "gc/shared/cardTableRS.hpp" 36 #include "gc/shared/collectedHeap.inline.hpp" 37 #include "gc/shared/collectorCounters.hpp" 38 #include "gc/shared/gcId.hpp" 39 #include "gc/shared/gcLocker.hpp" 40 #include "gc/shared/gcPolicyCounters.hpp" 41 #include "gc/shared/gcTrace.hpp" 42 #include "gc/shared/gcTraceTime.inline.hpp" 43 #include "gc/shared/genCollectedHeap.hpp" 44 #include "gc/shared/genOopClosures.inline.hpp" 45 #include "gc/shared/generationSpec.hpp" 46 #include "gc/shared/space.hpp" 47 #include "gc/shared/strongRootsScope.hpp" 48 #include "gc/shared/vmGCOperations.hpp" 49 #include "gc/shared/weakProcessor.hpp" 50 #include "gc/shared/workgroup.hpp" 51 #include "memory/filemap.hpp" 52 #include "memory/metaspaceCounters.hpp" 53 #include "memory/resourceArea.hpp" 54 #include "oops/oop.inline.hpp" 55 #include "runtime/biasedLocking.hpp" 56 #include "runtime/handles.hpp" 57 #include "runtime/handles.inline.hpp" 58 #include "runtime/java.hpp" 59 #include "runtime/vmThread.hpp" 60 #include "services/management.hpp" 61 #include "services/memoryService.hpp" 62 #include "utilities/debug.hpp" 63 #include "utilities/formatBuffer.hpp" 64 #include "utilities/macros.hpp" 65 #include "utilities/stack.inline.hpp" 66 #include "utilities/vmError.hpp" 67 68 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy, 69 Generation::Name young, 70 Generation::Name old, 71 const char* policy_counters_name) : 72 CollectedHeap(), 73 _rem_set(NULL), 74 _young_gen_spec(new GenerationSpec(young, 75 policy->initial_young_size(), 76 policy->max_young_size(), 77 policy->gen_alignment())), 78 _old_gen_spec(new GenerationSpec(old, 79 policy->initial_old_size(), 80 policy->max_old_size(), 81 policy->gen_alignment())), 82 _gen_policy(policy), 83 _soft_ref_gen_policy(), 84 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)), 85 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)), 86 _full_collections_completed(0) { 87 } 88 89 jint GenCollectedHeap::initialize() { 90 // While there are no constraints in the GC code that HeapWordSize 91 // be any particular value, there are multiple other areas in the 92 // system which believe this to be true (e.g. oop->object_size in some 93 // cases incorrectly returns the size in wordSize units rather than 94 // HeapWordSize). 95 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 96 97 // Allocate space for the heap. 98 99 char* heap_address; 100 ReservedSpace heap_rs; 101 102 size_t heap_alignment = collector_policy()->heap_alignment(); 103 104 heap_address = allocate(heap_alignment, &heap_rs); 105 106 if (!heap_rs.is_reserved()) { 107 vm_shutdown_during_initialization( 108 "Could not reserve enough space for object heap"); 109 return JNI_ENOMEM; 110 } 111 112 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 113 114 _rem_set = create_rem_set(reserved_region()); 115 _rem_set->initialize(); 116 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set); 117 bs->initialize(); 118 BarrierSet::set_barrier_set(bs); 119 120 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size(), false, false); 121 _young_gen = _young_gen_spec->init(young_rs, rem_set()); 122 heap_rs = heap_rs.last_part(_young_gen_spec->max_size()); 123 124 ReservedSpace old_rs = heap_rs.first_part(_old_gen_spec->max_size(), false, false); 125 _old_gen = _old_gen_spec->init(old_rs, rem_set()); 126 clear_incremental_collection_failed(); 127 128 return JNI_OK; 129 } 130 131 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) { 132 return new CardTableRS(reserved_region, false /* scan_concurrently */); 133 } 134 135 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size, 136 size_t init_promo_size, 137 size_t init_survivor_size) { 138 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0; 139 _size_policy = new AdaptiveSizePolicy(init_eden_size, 140 init_promo_size, 141 init_survivor_size, 142 max_gc_pause_sec, 143 GCTimeRatio); 144 } 145 146 char* GenCollectedHeap::allocate(size_t alignment, 147 ReservedSpace* heap_rs){ 148 // Now figure out the total size. 149 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 150 assert(alignment % pageSize == 0, "Must be"); 151 152 // Check for overflow. 153 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size(); 154 if (total_reserved < _young_gen_spec->max_size()) { 155 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 156 "the maximum representable size"); 157 } 158 assert(total_reserved % alignment == 0, 159 "Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 160 SIZE_FORMAT, total_reserved, alignment); 161 162 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 163 164 os::trace_page_sizes("Heap", 165 collector_policy()->min_heap_byte_size(), 166 total_reserved, 167 alignment, 168 heap_rs->base(), 169 heap_rs->size()); 170 171 return heap_rs->base(); 172 } 173 174 void GenCollectedHeap::post_initialize() { 175 CollectedHeap::post_initialize(); 176 ref_processing_init(); 177 check_gen_kinds(); 178 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 179 180 initialize_size_policy(def_new_gen->eden()->capacity(), 181 _old_gen->capacity(), 182 def_new_gen->from()->capacity()); 183 } 184 185 void GenCollectedHeap::ref_processing_init() { 186 _young_gen->ref_processor_init(); 187 _old_gen->ref_processor_init(); 188 } 189 190 GenerationSpec* GenCollectedHeap::young_gen_spec() const { 191 return _young_gen_spec; 192 } 193 194 GenerationSpec* GenCollectedHeap::old_gen_spec() const { 195 return _old_gen_spec; 196 } 197 198 size_t GenCollectedHeap::capacity() const { 199 return _young_gen->capacity() + _old_gen->capacity(); 200 } 201 202 size_t GenCollectedHeap::used() const { 203 return _young_gen->used() + _old_gen->used(); 204 } 205 206 void GenCollectedHeap::save_used_regions() { 207 _old_gen->save_used_region(); 208 _young_gen->save_used_region(); 209 } 210 211 size_t GenCollectedHeap::max_capacity() const { 212 return _young_gen->max_capacity() + _old_gen->max_capacity(); 213 } 214 215 // Update the _full_collections_completed counter 216 // at the end of a stop-world full GC. 217 unsigned int GenCollectedHeap::update_full_collections_completed() { 218 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 219 assert(_full_collections_completed <= _total_full_collections, 220 "Can't complete more collections than were started"); 221 _full_collections_completed = _total_full_collections; 222 ml.notify_all(); 223 return _full_collections_completed; 224 } 225 226 // Update the _full_collections_completed counter, as appropriate, 227 // at the end of a concurrent GC cycle. Note the conditional update 228 // below to allow this method to be called by a concurrent collector 229 // without synchronizing in any manner with the VM thread (which 230 // may already have initiated a STW full collection "concurrently"). 231 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 232 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 233 assert((_full_collections_completed <= _total_full_collections) && 234 (count <= _total_full_collections), 235 "Can't complete more collections than were started"); 236 if (count > _full_collections_completed) { 237 _full_collections_completed = count; 238 ml.notify_all(); 239 } 240 return _full_collections_completed; 241 } 242 243 // Return true if any of the following is true: 244 // . the allocation won't fit into the current young gen heap 245 // . gc locker is occupied (jni critical section) 246 // . heap memory is tight -- the most recent previous collection 247 // was a full collection because a partial collection (would 248 // have) failed and is likely to fail again 249 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const { 250 size_t young_capacity = young_gen()->capacity_before_gc(); 251 return (word_size > heap_word_size(young_capacity)) 252 || GCLocker::is_active_and_needs_gc() 253 || incremental_collection_failed(); 254 } 255 256 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) { 257 HeapWord* result = NULL; 258 if (old_gen()->should_allocate(size, is_tlab)) { 259 result = old_gen()->expand_and_allocate(size, is_tlab); 260 } 261 if (result == NULL) { 262 if (young_gen()->should_allocate(size, is_tlab)) { 263 result = young_gen()->expand_and_allocate(size, is_tlab); 264 } 265 } 266 assert(result == NULL || is_in_reserved(result), "result not in heap"); 267 return result; 268 } 269 270 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size, 271 bool is_tlab, 272 bool* gc_overhead_limit_was_exceeded) { 273 debug_only(check_for_valid_allocation_state()); 274 assert(no_gc_in_progress(), "Allocation during gc not allowed"); 275 276 // In general gc_overhead_limit_was_exceeded should be false so 277 // set it so here and reset it to true only if the gc time 278 // limit is being exceeded as checked below. 279 *gc_overhead_limit_was_exceeded = false; 280 281 HeapWord* result = NULL; 282 283 // Loop until the allocation is satisfied, or unsatisfied after GC. 284 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) { 285 HandleMark hm; // Discard any handles allocated in each iteration. 286 287 // First allocation attempt is lock-free. 288 Generation *young = young_gen(); 289 assert(young->supports_inline_contig_alloc(), 290 "Otherwise, must do alloc within heap lock"); 291 if (young->should_allocate(size, is_tlab)) { 292 result = young->par_allocate(size, is_tlab); 293 if (result != NULL) { 294 assert(is_in_reserved(result), "result not in heap"); 295 return result; 296 } 297 } 298 uint gc_count_before; // Read inside the Heap_lock locked region. 299 { 300 MutexLocker ml(Heap_lock); 301 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation"); 302 // Note that only large objects get a shot at being 303 // allocated in later generations. 304 bool first_only = !should_try_older_generation_allocation(size); 305 306 result = attempt_allocation(size, is_tlab, first_only); 307 if (result != NULL) { 308 assert(is_in_reserved(result), "result not in heap"); 309 return result; 310 } 311 312 if (GCLocker::is_active_and_needs_gc()) { 313 if (is_tlab) { 314 return NULL; // Caller will retry allocating individual object. 315 } 316 if (!is_maximal_no_gc()) { 317 // Try and expand heap to satisfy request. 318 result = expand_heap_and_allocate(size, is_tlab); 319 // Result could be null if we are out of space. 320 if (result != NULL) { 321 return result; 322 } 323 } 324 325 if (gclocker_stalled_count > GCLockerRetryAllocationCount) { 326 return NULL; // We didn't get to do a GC and we didn't get any memory. 327 } 328 329 // If this thread is not in a jni critical section, we stall 330 // the requestor until the critical section has cleared and 331 // GC allowed. When the critical section clears, a GC is 332 // initiated by the last thread exiting the critical section; so 333 // we retry the allocation sequence from the beginning of the loop, 334 // rather than causing more, now probably unnecessary, GC attempts. 335 JavaThread* jthr = JavaThread::current(); 336 if (!jthr->in_critical()) { 337 MutexUnlocker mul(Heap_lock); 338 // Wait for JNI critical section to be exited 339 GCLocker::stall_until_clear(); 340 gclocker_stalled_count += 1; 341 continue; 342 } else { 343 if (CheckJNICalls) { 344 fatal("Possible deadlock due to allocating while" 345 " in jni critical section"); 346 } 347 return NULL; 348 } 349 } 350 351 // Read the gc count while the heap lock is held. 352 gc_count_before = total_collections(); 353 } 354 355 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before); 356 VMThread::execute(&op); 357 if (op.prologue_succeeded()) { 358 result = op.result(); 359 if (op.gc_locked()) { 360 assert(result == NULL, "must be NULL if gc_locked() is true"); 361 continue; // Retry and/or stall as necessary. 362 } 363 364 // Allocation has failed and a collection 365 // has been done. If the gc time limit was exceeded the 366 // this time, return NULL so that an out-of-memory 367 // will be thrown. Clear gc_overhead_limit_exceeded 368 // so that the overhead exceeded does not persist. 369 370 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded(); 371 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear(); 372 373 if (limit_exceeded && softrefs_clear) { 374 *gc_overhead_limit_was_exceeded = true; 375 size_policy()->set_gc_overhead_limit_exceeded(false); 376 if (op.result() != NULL) { 377 CollectedHeap::fill_with_object(op.result(), size); 378 } 379 return NULL; 380 } 381 assert(result == NULL || is_in_reserved(result), 382 "result not in heap"); 383 return result; 384 } 385 386 // Give a warning if we seem to be looping forever. 387 if ((QueuedAllocationWarningCount > 0) && 388 (try_count % QueuedAllocationWarningCount == 0)) { 389 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times," 390 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : ""); 391 } 392 } 393 } 394 395 #ifndef PRODUCT 396 // Override of memory state checking method in CollectedHeap: 397 // Some collectors (CMS for example) can't have badHeapWordVal written 398 // in the first two words of an object. (For instance , in the case of 399 // CMS these words hold state used to synchronize between certain 400 // (concurrent) GC steps and direct allocating mutators.) 401 // The skip_header_HeapWords() method below, allows us to skip 402 // over the requisite number of HeapWord's. Note that (for 403 // generational collectors) this means that those many words are 404 // skipped in each object, irrespective of the generation in which 405 // that object lives. The resultant loss of precision seems to be 406 // harmless and the pain of avoiding that imprecision appears somewhat 407 // higher than we are prepared to pay for such rudimentary debugging 408 // support. 409 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 410 size_t size) { 411 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 412 // We are asked to check a size in HeapWords, 413 // but the memory is mangled in juint words. 414 juint* start = (juint*) (addr + skip_header_HeapWords()); 415 juint* end = (juint*) (addr + size); 416 for (juint* slot = start; slot < end; slot += 1) { 417 assert(*slot == badHeapWordVal, 418 "Found non badHeapWordValue in pre-allocation check"); 419 } 420 } 421 } 422 #endif 423 424 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 425 bool is_tlab, 426 bool first_only) { 427 HeapWord* res = NULL; 428 429 if (_young_gen->should_allocate(size, is_tlab)) { 430 res = _young_gen->allocate(size, is_tlab); 431 if (res != NULL || first_only) { 432 return res; 433 } 434 } 435 436 if (_old_gen->should_allocate(size, is_tlab)) { 437 res = _old_gen->allocate(size, is_tlab); 438 } 439 440 return res; 441 } 442 443 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 444 bool* gc_overhead_limit_was_exceeded) { 445 return mem_allocate_work(size, 446 false /* is_tlab */, 447 gc_overhead_limit_was_exceeded); 448 } 449 450 bool GenCollectedHeap::must_clear_all_soft_refs() { 451 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || 452 _gc_cause == GCCause::_wb_full_gc; 453 } 454 455 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 456 bool is_tlab, bool run_verification, bool clear_soft_refs, 457 bool restore_marks_for_biased_locking) { 458 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 459 GCTraceTime(Trace, gc, phases) t1(title); 460 TraceCollectorStats tcs(gen->counters()); 461 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause()); 462 463 gen->stat_record()->invocations++; 464 gen->stat_record()->accumulated_time.start(); 465 466 // Must be done anew before each collection because 467 // a previous collection will do mangling and will 468 // change top of some spaces. 469 record_gen_tops_before_GC(); 470 471 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 472 473 if (run_verification && VerifyBeforeGC) { 474 HandleMark hm; // Discard invalid handles created during verification 475 Universe::verify("Before GC"); 476 } 477 COMPILER2_PRESENT(DerivedPointerTable::clear()); 478 479 if (restore_marks_for_biased_locking) { 480 // We perform this mark word preservation work lazily 481 // because it's only at this point that we know whether we 482 // absolutely have to do it; we want to avoid doing it for 483 // scavenge-only collections where it's unnecessary 484 BiasedLocking::preserve_marks(); 485 } 486 487 // Do collection work 488 { 489 // Note on ref discovery: For what appear to be historical reasons, 490 // GCH enables and disabled (by enqueing) refs discovery. 491 // In the future this should be moved into the generation's 492 // collect method so that ref discovery and enqueueing concerns 493 // are local to a generation. The collect method could return 494 // an appropriate indication in the case that notification on 495 // the ref lock was needed. This will make the treatment of 496 // weak refs more uniform (and indeed remove such concerns 497 // from GCH). XXX 498 499 HandleMark hm; // Discard invalid handles created during gc 500 save_marks(); // save marks for all gens 501 // We want to discover references, but not process them yet. 502 // This mode is disabled in process_discovered_references if the 503 // generation does some collection work, or in 504 // enqueue_discovered_references if the generation returns 505 // without doing any work. 506 ReferenceProcessor* rp = gen->ref_processor(); 507 // If the discovery of ("weak") refs in this generation is 508 // atomic wrt other collectors in this configuration, we 509 // are guaranteed to have empty discovered ref lists. 510 if (rp->discovery_is_atomic()) { 511 rp->enable_discovery(); 512 rp->setup_policy(clear_soft_refs); 513 } else { 514 // collect() below will enable discovery as appropriate 515 } 516 gen->collect(full, clear_soft_refs, size, is_tlab); 517 if (!rp->enqueuing_is_done()) { 518 ReferenceProcessorPhaseTimes pt(NULL, rp->num_queues()); 519 rp->enqueue_discovered_references(NULL, &pt); 520 pt.print_enqueue_phase(); 521 } else { 522 rp->set_enqueuing_is_done(false); 523 } 524 rp->verify_no_references_recorded(); 525 } 526 527 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 528 529 gen->stat_record()->accumulated_time.stop(); 530 531 update_gc_stats(gen, full); 532 533 if (run_verification && VerifyAfterGC) { 534 HandleMark hm; // Discard invalid handles created during verification 535 Universe::verify("After GC"); 536 } 537 } 538 539 void GenCollectedHeap::do_collection(bool full, 540 bool clear_all_soft_refs, 541 size_t size, 542 bool is_tlab, 543 GenerationType max_generation) { 544 ResourceMark rm; 545 DEBUG_ONLY(Thread* my_thread = Thread::current();) 546 547 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 548 assert(my_thread->is_VM_thread() || 549 my_thread->is_ConcurrentGC_thread(), 550 "incorrect thread type capability"); 551 assert(Heap_lock->is_locked(), 552 "the requesting thread should have the Heap_lock"); 553 guarantee(!is_gc_active(), "collection is not reentrant"); 554 555 if (GCLocker::check_active_before_gc()) { 556 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 557 } 558 559 GCIdMark gc_id_mark; 560 561 const bool do_clear_all_soft_refs = clear_all_soft_refs || 562 soft_ref_policy()->should_clear_all_soft_refs(); 563 564 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy()); 565 566 const size_t metadata_prev_used = MetaspaceUtils::used_bytes(); 567 568 print_heap_before_gc(); 569 570 { 571 FlagSetting fl(_is_gc_active, true); 572 573 bool complete = full && (max_generation == OldGen); 574 bool old_collects_young = complete && !ScavengeBeforeFullGC; 575 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 576 577 FormatBuffer<> gc_string("%s", "Pause "); 578 if (do_young_collection) { 579 gc_string.append("Young"); 580 } else { 581 gc_string.append("Full"); 582 } 583 584 GCTraceCPUTime tcpu; 585 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true); 586 587 gc_prologue(complete); 588 increment_total_collections(complete); 589 590 size_t young_prev_used = _young_gen->used(); 591 size_t old_prev_used = _old_gen->used(); 592 593 bool run_verification = total_collections() >= VerifyGCStartAt; 594 595 bool prepared_for_verification = false; 596 bool collected_old = false; 597 598 if (do_young_collection) { 599 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 600 prepare_for_verify(); 601 prepared_for_verification = true; 602 } 603 604 collect_generation(_young_gen, 605 full, 606 size, 607 is_tlab, 608 run_verification && VerifyGCLevel <= 0, 609 do_clear_all_soft_refs, 610 false); 611 612 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 613 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 614 // Allocation request was met by young GC. 615 size = 0; 616 } 617 } 618 619 bool must_restore_marks_for_biased_locking = false; 620 621 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 622 if (!complete) { 623 // The full_collections increment was missed above. 624 increment_total_full_collections(); 625 } 626 627 if (!prepared_for_verification && run_verification && 628 VerifyGCLevel <= 1 && VerifyBeforeGC) { 629 prepare_for_verify(); 630 } 631 632 if (do_young_collection) { 633 // We did a young GC. Need a new GC id for the old GC. 634 GCIdMark gc_id_mark; 635 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 636 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 637 } else { 638 // No young GC done. Use the same GC id as was set up earlier in this method. 639 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 640 } 641 642 must_restore_marks_for_biased_locking = true; 643 collected_old = true; 644 } 645 646 // Update "complete" boolean wrt what actually transpired -- 647 // for instance, a promotion failure could have led to 648 // a whole heap collection. 649 complete = complete || collected_old; 650 651 print_heap_change(young_prev_used, old_prev_used); 652 MetaspaceUtils::print_metaspace_change(metadata_prev_used); 653 654 // Adjust generation sizes. 655 if (collected_old) { 656 _old_gen->compute_new_size(); 657 } 658 _young_gen->compute_new_size(); 659 660 if (complete) { 661 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 662 ClassLoaderDataGraph::purge(); 663 MetaspaceUtils::verify_metrics(); 664 // Resize the metaspace capacity after full collections 665 MetaspaceGC::compute_new_size(); 666 update_full_collections_completed(); 667 } 668 669 // Track memory usage and detect low memory after GC finishes 670 MemoryService::track_memory_usage(); 671 672 gc_epilogue(complete); 673 674 if (must_restore_marks_for_biased_locking) { 675 BiasedLocking::restore_marks(); 676 } 677 } 678 679 print_heap_after_gc(); 680 681 #ifdef TRACESPINNING 682 ParallelTaskTerminator::print_termination_counts(); 683 #endif 684 } 685 686 void GenCollectedHeap::register_nmethod(nmethod* nm) { 687 CodeCache::register_scavenge_root_nmethod(nm); 688 } 689 690 void GenCollectedHeap::verify_nmethod(nmethod* nm) { 691 CodeCache::verify_scavenge_root_nmethod(nm); 692 } 693 694 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 695 GCCauseSetter x(this, GCCause::_allocation_failure); 696 HeapWord* result = NULL; 697 698 assert(size != 0, "Precondition violated"); 699 if (GCLocker::is_active_and_needs_gc()) { 700 // GC locker is active; instead of a collection we will attempt 701 // to expand the heap, if there's room for expansion. 702 if (!is_maximal_no_gc()) { 703 result = expand_heap_and_allocate(size, is_tlab); 704 } 705 return result; // Could be null if we are out of space. 706 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) { 707 // Do an incremental collection. 708 do_collection(false, // full 709 false, // clear_all_soft_refs 710 size, // size 711 is_tlab, // is_tlab 712 GenCollectedHeap::OldGen); // max_generation 713 } else { 714 log_trace(gc)(" :: Trying full because partial may fail :: "); 715 // Try a full collection; see delta for bug id 6266275 716 // for the original code and why this has been simplified 717 // with from-space allocation criteria modified and 718 // such allocation moved out of the safepoint path. 719 do_collection(true, // full 720 false, // clear_all_soft_refs 721 size, // size 722 is_tlab, // is_tlab 723 GenCollectedHeap::OldGen); // max_generation 724 } 725 726 result = attempt_allocation(size, is_tlab, false /*first_only*/); 727 728 if (result != NULL) { 729 assert(is_in_reserved(result), "result not in heap"); 730 return result; 731 } 732 733 // OK, collection failed, try expansion. 734 result = expand_heap_and_allocate(size, is_tlab); 735 if (result != NULL) { 736 return result; 737 } 738 739 // If we reach this point, we're really out of memory. Try every trick 740 // we can to reclaim memory. Force collection of soft references. Force 741 // a complete compaction of the heap. Any additional methods for finding 742 // free memory should be here, especially if they are expensive. If this 743 // attempt fails, an OOM exception will be thrown. 744 { 745 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted 746 747 do_collection(true, // full 748 true, // clear_all_soft_refs 749 size, // size 750 is_tlab, // is_tlab 751 GenCollectedHeap::OldGen); // max_generation 752 } 753 754 result = attempt_allocation(size, is_tlab, false /* first_only */); 755 if (result != NULL) { 756 assert(is_in_reserved(result), "result not in heap"); 757 return result; 758 } 759 760 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 761 "Flag should have been handled and cleared prior to this point"); 762 763 // What else? We might try synchronous finalization later. If the total 764 // space available is large enough for the allocation, then a more 765 // complete compaction phase than we've tried so far might be 766 // appropriate. 767 return NULL; 768 } 769 770 #ifdef ASSERT 771 class AssertNonScavengableClosure: public OopClosure { 772 public: 773 virtual void do_oop(oop* p) { 774 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 775 "Referent should not be scavengable."); } 776 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 777 }; 778 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 779 #endif 780 781 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 782 ScanningOption so, 783 OopClosure* strong_roots, 784 OopClosure* weak_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->is_task_claimed(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->is_task_claimed(GCH_PS_Universe_oops_do)) { 807 Universe::oops_do(strong_roots); 808 } 809 // Global (strong) JNI handles 810 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 811 JNIHandles::oops_do(strong_roots); 812 } 813 814 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 815 ObjectSynchronizer::oops_do(strong_roots); 816 } 817 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 818 Management::oops_do(strong_roots); 819 } 820 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 821 JvmtiExport::oops_do(strong_roots); 822 } 823 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) { 824 AOTLoader::oops_do(strong_roots); 825 } 826 827 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 828 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 829 } 830 831 if (!_process_strong_tasks->is_task_claimed(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 assert(root_closure != NULL, "Must be set"); 855 // All threads execute the following. A specific chunk of buckets 856 // from the StringTable are the individual tasks. 857 if (scope->n_threads() > 1) { 858 StringTable::possibly_parallel_oops_do(root_closure); 859 } else { 860 StringTable::oops_do(root_closure); 861 } 862 } 863 864 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope, 865 OopsInGenClosure* root_closure, 866 OopsInGenClosure* old_gen_closure, 867 CLDClosure* cld_closure) { 868 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations); 869 870 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure, 871 cld_closure, cld_closure, &mark_code_closure); 872 process_string_table_roots(scope, root_closure); 873 874 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 875 root_closure->reset_generation(); 876 } 877 878 // When collection is parallel, all threads get to cooperate to do 879 // old generation scanning. 880 old_gen_closure->set_generation(_old_gen); 881 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); 882 old_gen_closure->reset_generation(); 883 884 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 885 } 886 887 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope, 888 bool is_adjust_phase, 889 ScanningOption so, 890 bool only_strong_roots, 891 OopsInGenClosure* root_closure, 892 CLDClosure* cld_closure) { 893 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase); 894 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure; 895 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 896 897 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure); 898 if (is_adjust_phase) { 899 // We never treat the string table as roots during marking 900 // for the full gc, so we only need to process it during 901 // the adjust phase. 902 process_string_table_roots(scope, root_closure); 903 } 904 905 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 906 } 907 908 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 909 WeakProcessor::oops_do(root_closure); 910 _young_gen->ref_processor()->weak_oops_do(root_closure); 911 _old_gen->ref_processor()->weak_oops_do(root_closure); 912 } 913 914 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 915 void GenCollectedHeap:: \ 916 oop_since_save_marks_iterate(GenerationType gen, \ 917 OopClosureType* cur, \ 918 OopClosureType* older) { \ 919 if (gen == YoungGen) { \ 920 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 921 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 922 } else { \ 923 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 924 } \ 925 } 926 927 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 928 929 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 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_no_header(OopClosure* cl) { 1055 NoHeaderExtendedOopClosure no_header_cl(cl); 1056 oop_iterate(&no_header_cl); 1057 } 1058 1059 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 1060 _young_gen->oop_iterate(cl); 1061 _old_gen->oop_iterate(cl); 1062 } 1063 1064 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 1065 _young_gen->object_iterate(cl); 1066 _old_gen->object_iterate(cl); 1067 } 1068 1069 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 1070 _young_gen->safe_object_iterate(cl); 1071 _old_gen->safe_object_iterate(cl); 1072 } 1073 1074 Space* GenCollectedHeap::space_containing(const void* addr) const { 1075 Space* res = _young_gen->space_containing(addr); 1076 if (res != NULL) { 1077 return res; 1078 } 1079 res = _old_gen->space_containing(addr); 1080 assert(res != NULL, "Could not find containing space"); 1081 return res; 1082 } 1083 1084 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 1085 assert(is_in_reserved(addr), "block_start of address outside of heap"); 1086 if (_young_gen->is_in_reserved(addr)) { 1087 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 1088 return _young_gen->block_start(addr); 1089 } 1090 1091 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1092 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 1093 return _old_gen->block_start(addr); 1094 } 1095 1096 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 1097 assert(is_in_reserved(addr), "block_size of address outside of heap"); 1098 if (_young_gen->is_in_reserved(addr)) { 1099 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 1100 return _young_gen->block_size(addr); 1101 } 1102 1103 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1104 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 1105 return _old_gen->block_size(addr); 1106 } 1107 1108 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 1109 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 1110 assert(block_start(addr) == addr, "addr must be a block start"); 1111 if (_young_gen->is_in_reserved(addr)) { 1112 return _young_gen->block_is_obj(addr); 1113 } 1114 1115 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1116 return _old_gen->block_is_obj(addr); 1117 } 1118 1119 bool GenCollectedHeap::supports_tlab_allocation() const { 1120 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1121 return _young_gen->supports_tlab_allocation(); 1122 } 1123 1124 size_t GenCollectedHeap::tlab_capacity(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->tlab_capacity(); 1128 } 1129 return 0; 1130 } 1131 1132 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 1133 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1134 if (_young_gen->supports_tlab_allocation()) { 1135 return _young_gen->tlab_used(); 1136 } 1137 return 0; 1138 } 1139 1140 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 1141 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1142 if (_young_gen->supports_tlab_allocation()) { 1143 return _young_gen->unsafe_max_tlab_alloc(); 1144 } 1145 return 0; 1146 } 1147 1148 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 1149 bool gc_overhead_limit_was_exceeded; 1150 return mem_allocate_work(size /* size */, 1151 true /* is_tlab */, 1152 &gc_overhead_limit_was_exceeded); 1153 } 1154 1155 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1156 // from the list headed by "*prev_ptr". 1157 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1158 bool first = true; 1159 size_t min_size = 0; // "first" makes this conceptually infinite. 1160 ScratchBlock **smallest_ptr, *smallest; 1161 ScratchBlock *cur = *prev_ptr; 1162 while (cur) { 1163 assert(*prev_ptr == cur, "just checking"); 1164 if (first || cur->num_words < min_size) { 1165 smallest_ptr = prev_ptr; 1166 smallest = cur; 1167 min_size = smallest->num_words; 1168 first = false; 1169 } 1170 prev_ptr = &cur->next; 1171 cur = cur->next; 1172 } 1173 smallest = *smallest_ptr; 1174 *smallest_ptr = smallest->next; 1175 return smallest; 1176 } 1177 1178 // Sort the scratch block list headed by res into decreasing size order, 1179 // and set "res" to the result. 1180 static void sort_scratch_list(ScratchBlock*& list) { 1181 ScratchBlock* sorted = NULL; 1182 ScratchBlock* unsorted = list; 1183 while (unsorted) { 1184 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1185 smallest->next = sorted; 1186 sorted = smallest; 1187 } 1188 list = sorted; 1189 } 1190 1191 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1192 size_t max_alloc_words) { 1193 ScratchBlock* res = NULL; 1194 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1195 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1196 sort_scratch_list(res); 1197 return res; 1198 } 1199 1200 void GenCollectedHeap::release_scratch() { 1201 _young_gen->reset_scratch(); 1202 _old_gen->reset_scratch(); 1203 } 1204 1205 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1206 void do_generation(Generation* gen) { 1207 gen->prepare_for_verify(); 1208 } 1209 }; 1210 1211 void GenCollectedHeap::prepare_for_verify() { 1212 ensure_parsability(false); // no need to retire TLABs 1213 GenPrepareForVerifyClosure blk; 1214 generation_iterate(&blk, false); 1215 } 1216 1217 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1218 bool old_to_young) { 1219 if (old_to_young) { 1220 cl->do_generation(_old_gen); 1221 cl->do_generation(_young_gen); 1222 } else { 1223 cl->do_generation(_young_gen); 1224 cl->do_generation(_old_gen); 1225 } 1226 } 1227 1228 bool GenCollectedHeap::is_maximal_no_gc() const { 1229 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1230 } 1231 1232 void GenCollectedHeap::save_marks() { 1233 _young_gen->save_marks(); 1234 _old_gen->save_marks(); 1235 } 1236 1237 GenCollectedHeap* GenCollectedHeap::heap() { 1238 CollectedHeap* heap = Universe::heap(); 1239 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1240 assert(heap->kind() == CollectedHeap::Serial || 1241 heap->kind() == CollectedHeap::CMS, "Invalid name"); 1242 return (GenCollectedHeap*) heap; 1243 } 1244 1245 void GenCollectedHeap::prepare_for_compaction() { 1246 // Start by compacting into same gen. 1247 CompactPoint cp(_old_gen); 1248 _old_gen->prepare_for_compaction(&cp); 1249 _young_gen->prepare_for_compaction(&cp); 1250 } 1251 1252 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1253 log_debug(gc, verify)("%s", _old_gen->name()); 1254 _old_gen->verify(); 1255 1256 log_debug(gc, verify)("%s", _old_gen->name()); 1257 _young_gen->verify(); 1258 1259 log_debug(gc, verify)("RemSet"); 1260 rem_set()->verify(); 1261 } 1262 1263 void GenCollectedHeap::print_on(outputStream* st) const { 1264 _young_gen->print_on(st); 1265 _old_gen->print_on(st); 1266 MetaspaceUtils::print_on(st); 1267 } 1268 1269 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1270 } 1271 1272 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1273 } 1274 1275 void GenCollectedHeap::print_tracing_info() const { 1276 if (log_is_enabled(Debug, gc, heap, exit)) { 1277 LogStreamHandle(Debug, gc, heap, exit) lsh; 1278 _young_gen->print_summary_info_on(&lsh); 1279 _old_gen->print_summary_info_on(&lsh); 1280 } 1281 } 1282 1283 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1284 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1285 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1286 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1287 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1288 } 1289 1290 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1291 private: 1292 bool _full; 1293 public: 1294 void do_generation(Generation* gen) { 1295 gen->gc_prologue(_full); 1296 } 1297 GenGCPrologueClosure(bool full) : _full(full) {}; 1298 }; 1299 1300 void GenCollectedHeap::gc_prologue(bool full) { 1301 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1302 1303 // Fill TLAB's and such 1304 CollectedHeap::accumulate_statistics_all_tlabs(); 1305 ensure_parsability(true); // retire TLABs 1306 1307 // Walk generations 1308 GenGCPrologueClosure blk(full); 1309 generation_iterate(&blk, false); // not old-to-young. 1310 }; 1311 1312 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1313 private: 1314 bool _full; 1315 public: 1316 void do_generation(Generation* gen) { 1317 gen->gc_epilogue(_full); 1318 } 1319 GenGCEpilogueClosure(bool full) : _full(full) {}; 1320 }; 1321 1322 void GenCollectedHeap::gc_epilogue(bool full) { 1323 #if COMPILER2_OR_JVMCI 1324 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1325 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1326 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1327 #endif // COMPILER2_OR_JVMCI 1328 1329 resize_all_tlabs(); 1330 1331 GenGCEpilogueClosure blk(full); 1332 generation_iterate(&blk, false); // not old-to-young. 1333 1334 if (!CleanChunkPoolAsync) { 1335 Chunk::clean_chunk_pool(); 1336 } 1337 1338 MetaspaceCounters::update_performance_counters(); 1339 CompressedClassSpaceCounters::update_performance_counters(); 1340 }; 1341 1342 #ifndef PRODUCT 1343 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1344 private: 1345 public: 1346 void do_generation(Generation* gen) { 1347 gen->record_spaces_top(); 1348 } 1349 }; 1350 1351 void GenCollectedHeap::record_gen_tops_before_GC() { 1352 if (ZapUnusedHeapArea) { 1353 GenGCSaveTopsBeforeGCClosure blk; 1354 generation_iterate(&blk, false); // not old-to-young. 1355 } 1356 } 1357 #endif // not PRODUCT 1358 1359 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1360 public: 1361 void do_generation(Generation* gen) { 1362 gen->ensure_parsability(); 1363 } 1364 }; 1365 1366 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1367 CollectedHeap::ensure_parsability(retire_tlabs); 1368 GenEnsureParsabilityClosure ep_cl; 1369 generation_iterate(&ep_cl, false); 1370 } 1371 1372 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1373 oop obj, 1374 size_t obj_size) { 1375 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1376 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1377 HeapWord* result = NULL; 1378 1379 result = old_gen->expand_and_allocate(obj_size, false); 1380 1381 if (result != NULL) { 1382 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1383 } 1384 return oop(result); 1385 } 1386 1387 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1388 jlong _time; // in ms 1389 jlong _now; // in ms 1390 1391 public: 1392 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1393 1394 jlong time() { return _time; } 1395 1396 void do_generation(Generation* gen) { 1397 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1398 } 1399 }; 1400 1401 jlong GenCollectedHeap::millis_since_last_gc() { 1402 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1403 // provided the underlying platform provides such a time source 1404 // (and it is bug free). So we still have to guard against getting 1405 // back a time later than 'now'. 1406 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1407 GenTimeOfLastGCClosure tolgc_cl(now); 1408 // iterate over generations getting the oldest 1409 // time that a generation was collected 1410 generation_iterate(&tolgc_cl, false); 1411 1412 jlong retVal = now - tolgc_cl.time(); 1413 if (retVal < 0) { 1414 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 1415 ". returning zero instead.", retVal); 1416 return 0; 1417 } 1418 return retVal; 1419 }