1 /* 2 * Copyright (c) 2000, 2023, 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 "classfile/classLoaderDataGraph.hpp" 27 #include "classfile/stringTable.hpp" 28 #include "classfile/symbolTable.hpp" 29 #include "classfile/vmSymbols.hpp" 30 #include "code/codeCache.hpp" 31 #include "code/icBuffer.hpp" 32 #include "compiler/oopMap.hpp" 33 #include "gc/serial/cardTableRS.hpp" 34 #include "gc/serial/defNewGeneration.hpp" 35 #include "gc/serial/genMarkSweep.hpp" 36 #include "gc/serial/markSweep.hpp" 37 #include "gc/shared/adaptiveSizePolicy.hpp" 38 #include "gc/shared/cardTableBarrierSet.hpp" 39 #include "gc/shared/collectedHeap.inline.hpp" 40 #include "gc/shared/collectorCounters.hpp" 41 #include "gc/shared/continuationGCSupport.inline.hpp" 42 #include "gc/shared/gcId.hpp" 43 #include "gc/shared/gcInitLogger.hpp" 44 #include "gc/shared/gcLocker.hpp" 45 #include "gc/shared/gcPolicyCounters.hpp" 46 #include "gc/shared/gcTrace.hpp" 47 #include "gc/shared/gcTraceTime.inline.hpp" 48 #include "gc/shared/gcVMOperations.hpp" 49 #include "gc/shared/genArguments.hpp" 50 #include "gc/shared/genCollectedHeap.hpp" 51 #include "gc/shared/generationSpec.hpp" 52 #include "gc/shared/locationPrinter.inline.hpp" 53 #include "gc/shared/oopStorage.inline.hpp" 54 #include "gc/shared/oopStorageParState.inline.hpp" 55 #include "gc/shared/oopStorageSet.inline.hpp" 56 #include "gc/shared/scavengableNMethods.hpp" 57 #include "gc/shared/slidingForwarding.hpp" 58 #include "gc/shared/space.hpp" 59 #include "gc/shared/strongRootsScope.hpp" 60 #include "gc/shared/weakProcessor.hpp" 61 #include "gc/shared/workerThread.hpp" 62 #include "memory/iterator.hpp" 63 #include "memory/metaspaceCounters.hpp" 64 #include "memory/metaspaceUtils.hpp" 65 #include "memory/resourceArea.hpp" 66 #include "memory/universe.hpp" 67 #include "oops/oop.inline.hpp" 68 #include "runtime/handles.hpp" 69 #include "runtime/handles.inline.hpp" 70 #include "runtime/java.hpp" 71 #include "runtime/threads.hpp" 72 #include "runtime/vmThread.hpp" 73 #include "services/memoryService.hpp" 74 #include "utilities/autoRestore.hpp" 75 #include "utilities/debug.hpp" 76 #include "utilities/formatBuffer.hpp" 77 #include "utilities/macros.hpp" 78 #include "utilities/stack.inline.hpp" 79 #include "utilities/vmError.hpp" 80 #if INCLUDE_JVMCI 81 #include "jvmci/jvmci.hpp" 82 #endif 83 84 GenCollectedHeap::GenCollectedHeap(Generation::Name young, 85 Generation::Name old, 86 const char* policy_counters_name) : 87 CollectedHeap(), 88 _young_gen(nullptr), 89 _old_gen(nullptr), 90 _young_gen_spec(new GenerationSpec(young, 91 NewSize, 92 MaxNewSize, 93 GenAlignment)), 94 _old_gen_spec(new GenerationSpec(old, 95 OldSize, 96 MaxOldSize, 97 GenAlignment)), 98 _rem_set(nullptr), 99 _soft_ref_gen_policy(), 100 _size_policy(nullptr), 101 _gc_policy_counters(new GCPolicyCounters(policy_counters_name, 2, 2)), 102 _incremental_collection_failed(false), 103 _full_collections_completed(0), 104 _young_manager(nullptr), 105 _old_manager(nullptr) { 106 } 107 108 jint GenCollectedHeap::initialize() { 109 // Allocate space for the heap. 110 111 ReservedHeapSpace heap_rs = allocate(HeapAlignment); 112 113 if (!heap_rs.is_reserved()) { 114 vm_shutdown_during_initialization( 115 "Could not reserve enough space for object heap"); 116 return JNI_ENOMEM; 117 } 118 119 initialize_reserved_region(heap_rs); 120 121 ReservedSpace young_rs = heap_rs.first_part(_young_gen_spec->max_size()); 122 ReservedSpace old_rs = heap_rs.last_part(_young_gen_spec->max_size()); 123 124 _rem_set = create_rem_set(heap_rs.region()); 125 _rem_set->initialize(young_rs.base(), old_rs.base()); 126 127 CardTableBarrierSet *bs = new CardTableBarrierSet(_rem_set); 128 bs->initialize(); 129 BarrierSet::set_barrier_set(bs); 130 131 _young_gen = _young_gen_spec->init(young_rs, rem_set()); 132 _old_gen = _old_gen_spec->init(old_rs, rem_set()); 133 134 GCInitLogger::print(); 135 136 SlidingForwarding::initialize(_reserved, SpaceAlignment / HeapWordSize); 137 138 return JNI_OK; 139 } 140 141 CardTableRS* GenCollectedHeap::create_rem_set(const MemRegion& reserved_region) { 142 return new CardTableRS(reserved_region); 143 } 144 145 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size, 146 size_t init_promo_size, 147 size_t init_survivor_size) { 148 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0; 149 _size_policy = new AdaptiveSizePolicy(init_eden_size, 150 init_promo_size, 151 init_survivor_size, 152 max_gc_pause_sec, 153 GCTimeRatio); 154 } 155 156 ReservedHeapSpace GenCollectedHeap::allocate(size_t alignment) { 157 // Now figure out the total size. 158 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 159 assert(alignment % pageSize == 0, "Must be"); 160 161 // Check for overflow. 162 size_t total_reserved = _young_gen_spec->max_size() + _old_gen_spec->max_size(); 163 if (total_reserved < _young_gen_spec->max_size()) { 164 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 165 "the maximum representable size"); 166 } 167 assert(total_reserved % alignment == 0, 168 "Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 169 SIZE_FORMAT, total_reserved, alignment); 170 171 ReservedHeapSpace heap_rs = Universe::reserve_heap(total_reserved, alignment); 172 size_t used_page_size = heap_rs.page_size(); 173 174 os::trace_page_sizes("Heap", 175 MinHeapSize, 176 total_reserved, 177 used_page_size, 178 heap_rs.base(), 179 heap_rs.size()); 180 181 return heap_rs; 182 } 183 184 class GenIsScavengable : public BoolObjectClosure { 185 public: 186 bool do_object_b(oop obj) { 187 return GenCollectedHeap::heap()->is_in_young(obj); 188 } 189 }; 190 191 static GenIsScavengable _is_scavengable; 192 193 void GenCollectedHeap::post_initialize() { 194 CollectedHeap::post_initialize(); 195 196 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 197 198 def_new_gen->ref_processor_init(); 199 200 initialize_size_policy(def_new_gen->eden()->capacity(), 201 _old_gen->capacity(), 202 def_new_gen->from()->capacity()); 203 204 MarkSweep::initialize(); 205 206 ScavengableNMethods::initialize(&_is_scavengable); 207 } 208 209 PreGenGCValues GenCollectedHeap::get_pre_gc_values() const { 210 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen(); 211 212 return PreGenGCValues(def_new_gen->used(), 213 def_new_gen->capacity(), 214 def_new_gen->eden()->used(), 215 def_new_gen->eden()->capacity(), 216 def_new_gen->from()->used(), 217 def_new_gen->from()->capacity(), 218 old_gen()->used(), 219 old_gen()->capacity()); 220 } 221 222 GenerationSpec* GenCollectedHeap::young_gen_spec() const { 223 return _young_gen_spec; 224 } 225 226 GenerationSpec* GenCollectedHeap::old_gen_spec() const { 227 return _old_gen_spec; 228 } 229 230 size_t GenCollectedHeap::capacity() const { 231 return _young_gen->capacity() + _old_gen->capacity(); 232 } 233 234 size_t GenCollectedHeap::used() const { 235 return _young_gen->used() + _old_gen->used(); 236 } 237 238 void GenCollectedHeap::save_used_regions() { 239 _old_gen->save_used_region(); 240 _young_gen->save_used_region(); 241 } 242 243 size_t GenCollectedHeap::max_capacity() const { 244 return _young_gen->max_capacity() + _old_gen->max_capacity(); 245 } 246 247 // Update the _full_collections_completed counter 248 // at the end of a stop-world full GC. 249 unsigned int GenCollectedHeap::update_full_collections_completed() { 250 assert(_full_collections_completed <= _total_full_collections, 251 "Can't complete more collections than were started"); 252 _full_collections_completed = _total_full_collections; 253 return _full_collections_completed; 254 } 255 256 // Return true if any of the following is true: 257 // . the allocation won't fit into the current young gen heap 258 // . gc locker is occupied (jni critical section) 259 // . heap memory is tight -- the most recent previous collection 260 // was a full collection because a partial collection (would 261 // have) failed and is likely to fail again 262 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const { 263 size_t young_capacity = _young_gen->capacity_before_gc(); 264 return (word_size > heap_word_size(young_capacity)) 265 || GCLocker::is_active_and_needs_gc() 266 || incremental_collection_failed(); 267 } 268 269 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) { 270 HeapWord* result = nullptr; 271 if (_old_gen->should_allocate(size, is_tlab)) { 272 result = _old_gen->expand_and_allocate(size, is_tlab); 273 } 274 if (result == nullptr) { 275 if (_young_gen->should_allocate(size, is_tlab)) { 276 result = _young_gen->expand_and_allocate(size, is_tlab); 277 } 278 } 279 assert(result == nullptr || is_in_reserved(result), "result not in heap"); 280 return result; 281 } 282 283 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size, 284 bool is_tlab) { 285 286 HeapWord* result = nullptr; 287 288 // Loop until the allocation is satisfied, or unsatisfied after GC. 289 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) { 290 291 // First allocation attempt is lock-free. 292 Generation *young = _young_gen; 293 if (young->should_allocate(size, is_tlab)) { 294 result = young->par_allocate(size, is_tlab); 295 if (result != nullptr) { 296 assert(is_in_reserved(result), "result not in heap"); 297 return result; 298 } 299 } 300 uint gc_count_before; // Read inside the Heap_lock locked region. 301 { 302 MutexLocker ml(Heap_lock); 303 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation"); 304 // Note that only large objects get a shot at being 305 // allocated in later generations. 306 bool first_only = !should_try_older_generation_allocation(size); 307 308 result = attempt_allocation(size, is_tlab, first_only); 309 if (result != nullptr) { 310 assert(is_in_reserved(result), "result not in heap"); 311 return result; 312 } 313 314 if (GCLocker::is_active_and_needs_gc()) { 315 if (is_tlab) { 316 return nullptr; // Caller will retry allocating individual object. 317 } 318 if (!is_maximal_no_gc()) { 319 // Try and expand heap to satisfy request. 320 result = expand_heap_and_allocate(size, is_tlab); 321 // Result could be null if we are out of space. 322 if (result != nullptr) { 323 return result; 324 } 325 } 326 327 if (gclocker_stalled_count > GCLockerRetryAllocationCount) { 328 return nullptr; // We didn't get to do a GC and we didn't get any memory. 329 } 330 331 // If this thread is not in a jni critical section, we stall 332 // the requestor until the critical section has cleared and 333 // GC allowed. When the critical section clears, a GC is 334 // initiated by the last thread exiting the critical section; so 335 // we retry the allocation sequence from the beginning of the loop, 336 // rather than causing more, now probably unnecessary, GC attempts. 337 JavaThread* jthr = JavaThread::current(); 338 if (!jthr->in_critical()) { 339 MutexUnlocker mul(Heap_lock); 340 // Wait for JNI critical section to be exited 341 GCLocker::stall_until_clear(); 342 gclocker_stalled_count += 1; 343 continue; 344 } else { 345 if (CheckJNICalls) { 346 fatal("Possible deadlock due to allocating while" 347 " in jni critical section"); 348 } 349 return nullptr; 350 } 351 } 352 353 // Read the gc count while the heap lock is held. 354 gc_count_before = total_collections(); 355 } 356 357 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before); 358 VMThread::execute(&op); 359 if (op.prologue_succeeded()) { 360 result = op.result(); 361 if (op.gc_locked()) { 362 assert(result == nullptr, "must be null if gc_locked() is true"); 363 continue; // Retry and/or stall as necessary. 364 } 365 366 assert(result == nullptr || is_in_reserved(result), 367 "result not in heap"); 368 return result; 369 } 370 371 // Give a warning if we seem to be looping forever. 372 if ((QueuedAllocationWarningCount > 0) && 373 (try_count % QueuedAllocationWarningCount == 0)) { 374 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times," 375 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : ""); 376 } 377 } 378 } 379 380 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 381 bool is_tlab, 382 bool first_only) { 383 HeapWord* res = nullptr; 384 385 if (_young_gen->should_allocate(size, is_tlab)) { 386 res = _young_gen->allocate(size, is_tlab); 387 if (res != nullptr || first_only) { 388 return res; 389 } 390 } 391 392 if (_old_gen->should_allocate(size, is_tlab)) { 393 res = _old_gen->allocate(size, is_tlab); 394 } 395 396 return res; 397 } 398 399 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 400 bool* gc_overhead_limit_was_exceeded) { 401 return mem_allocate_work(size, 402 false /* is_tlab */); 403 } 404 405 bool GenCollectedHeap::must_clear_all_soft_refs() { 406 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || 407 _gc_cause == GCCause::_wb_full_gc; 408 } 409 410 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 411 bool is_tlab, bool run_verification, bool clear_soft_refs) { 412 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 413 GCTraceTime(Trace, gc, phases) t1(title); 414 TraceCollectorStats tcs(gen->counters()); 415 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause(), heap()->is_young_gen(gen) ? "end of minor GC" : "end of major GC"); 416 417 gen->stat_record()->invocations++; 418 gen->stat_record()->accumulated_time.start(); 419 420 // Must be done anew before each collection because 421 // a previous collection will do mangling and will 422 // change top of some spaces. 423 record_gen_tops_before_GC(); 424 425 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 426 427 if (run_verification && VerifyBeforeGC) { 428 Universe::verify("Before GC"); 429 } 430 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::clear()); 431 432 // Do collection work 433 { 434 save_marks(); // save marks for all gens 435 436 gen->collect(full, clear_soft_refs, size, is_tlab); 437 } 438 439 COMPILER2_OR_JVMCI_PRESENT(DerivedPointerTable::update_pointers()); 440 441 gen->stat_record()->accumulated_time.stop(); 442 443 update_gc_stats(gen, full); 444 445 if (run_verification && VerifyAfterGC) { 446 Universe::verify("After GC"); 447 } 448 } 449 450 void GenCollectedHeap::do_collection(bool full, 451 bool clear_all_soft_refs, 452 size_t size, 453 bool is_tlab, 454 GenerationType max_generation) { 455 ResourceMark rm; 456 DEBUG_ONLY(Thread* my_thread = Thread::current();) 457 458 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 459 assert(my_thread->is_VM_thread(), "only VM thread"); 460 assert(Heap_lock->is_locked(), 461 "the requesting thread should have the Heap_lock"); 462 guarantee(!is_gc_active(), "collection is not reentrant"); 463 464 if (GCLocker::check_active_before_gc()) { 465 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 466 } 467 468 const bool do_clear_all_soft_refs = clear_all_soft_refs || 469 soft_ref_policy()->should_clear_all_soft_refs(); 470 471 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy()); 472 473 AutoModifyRestore<bool> temporarily(_is_gc_active, true); 474 475 bool complete = full && (max_generation == OldGen); 476 bool old_collects_young = complete && !ScavengeBeforeFullGC; 477 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 478 479 const PreGenGCValues pre_gc_values = get_pre_gc_values(); 480 481 bool run_verification = total_collections() >= VerifyGCStartAt; 482 bool prepared_for_verification = false; 483 bool do_full_collection = false; 484 485 if (do_young_collection) { 486 GCIdMark gc_id_mark; 487 GCTraceCPUTime tcpu(((DefNewGeneration*)_young_gen)->gc_tracer()); 488 GCTraceTime(Info, gc) t("Pause Young", nullptr, gc_cause(), true); 489 490 print_heap_before_gc(); 491 492 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 493 prepare_for_verify(); 494 prepared_for_verification = true; 495 } 496 497 gc_prologue(complete); 498 increment_total_collections(complete); 499 500 collect_generation(_young_gen, 501 full, 502 size, 503 is_tlab, 504 run_verification && VerifyGCLevel <= 0, 505 do_clear_all_soft_refs); 506 507 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 508 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 509 // Allocation request was met by young GC. 510 size = 0; 511 } 512 513 // Ask if young collection is enough. If so, do the final steps for young collection, 514 // and fallthrough to the end. 515 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation); 516 if (!do_full_collection) { 517 // Adjust generation sizes. 518 _young_gen->compute_new_size(); 519 520 print_heap_change(pre_gc_values); 521 522 // Track memory usage and detect low memory after GC finishes 523 MemoryService::track_memory_usage(); 524 525 gc_epilogue(complete); 526 } 527 528 print_heap_after_gc(); 529 530 } else { 531 // No young collection, ask if we need to perform Full collection. 532 do_full_collection = should_do_full_collection(size, full, is_tlab, max_generation); 533 } 534 535 if (do_full_collection) { 536 GCIdMark gc_id_mark; 537 GCTraceCPUTime tcpu(GenMarkSweep::gc_tracer()); 538 GCTraceTime(Info, gc) t("Pause Full", nullptr, gc_cause(), true); 539 540 print_heap_before_gc(); 541 542 if (!prepared_for_verification && run_verification && 543 VerifyGCLevel <= 1 && VerifyBeforeGC) { 544 prepare_for_verify(); 545 } 546 547 if (!do_young_collection) { 548 gc_prologue(complete); 549 increment_total_collections(complete); 550 } 551 552 // Accounting quirk: total full collections would be incremented when "complete" 553 // is set, by calling increment_total_collections above. However, we also need to 554 // account Full collections that had "complete" unset. 555 if (!complete) { 556 increment_total_full_collections(); 557 } 558 559 CodeCache::on_gc_marking_cycle_start(); 560 561 collect_generation(_old_gen, 562 full, 563 size, 564 is_tlab, 565 run_verification && VerifyGCLevel <= 1, 566 do_clear_all_soft_refs); 567 568 CodeCache::on_gc_marking_cycle_finish(); 569 CodeCache::arm_all_nmethods(); 570 571 // Adjust generation sizes. 572 _old_gen->compute_new_size(); 573 _young_gen->compute_new_size(); 574 575 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 576 ClassLoaderDataGraph::purge(/*at_safepoint*/true); 577 DEBUG_ONLY(MetaspaceUtils::verify();) 578 579 // Need to clear claim bits for the next mark. 580 ClassLoaderDataGraph::clear_claimed_marks(); 581 582 // Resize the metaspace capacity after full collections 583 MetaspaceGC::compute_new_size(); 584 update_full_collections_completed(); 585 586 print_heap_change(pre_gc_values); 587 588 // Track memory usage and detect low memory after GC finishes 589 MemoryService::track_memory_usage(); 590 591 // Need to tell the epilogue code we are done with Full GC, regardless what was 592 // the initial value for "complete" flag. 593 gc_epilogue(true); 594 595 print_heap_after_gc(); 596 } 597 } 598 599 bool GenCollectedHeap::should_do_full_collection(size_t size, bool full, bool is_tlab, 600 GenCollectedHeap::GenerationType max_gen) const { 601 return max_gen == OldGen && _old_gen->should_collect(full, size, is_tlab); 602 } 603 604 void GenCollectedHeap::register_nmethod(nmethod* nm) { 605 ScavengableNMethods::register_nmethod(nm); 606 } 607 608 void GenCollectedHeap::unregister_nmethod(nmethod* nm) { 609 ScavengableNMethods::unregister_nmethod(nm); 610 } 611 612 void GenCollectedHeap::verify_nmethod(nmethod* nm) { 613 ScavengableNMethods::verify_nmethod(nm); 614 } 615 616 void GenCollectedHeap::prune_scavengable_nmethods() { 617 ScavengableNMethods::prune_nmethods(); 618 } 619 620 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 621 GCCauseSetter x(this, GCCause::_allocation_failure); 622 HeapWord* result = nullptr; 623 624 assert(size != 0, "Precondition violated"); 625 if (GCLocker::is_active_and_needs_gc()) { 626 // GC locker is active; instead of a collection we will attempt 627 // to expand the heap, if there's room for expansion. 628 if (!is_maximal_no_gc()) { 629 result = expand_heap_and_allocate(size, is_tlab); 630 } 631 return result; // Could be null if we are out of space. 632 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) { 633 // Do an incremental collection. 634 do_collection(false, // full 635 false, // clear_all_soft_refs 636 size, // size 637 is_tlab, // is_tlab 638 GenCollectedHeap::OldGen); // max_generation 639 } else { 640 log_trace(gc)(" :: Trying full because partial may fail :: "); 641 // Try a full collection; see delta for bug id 6266275 642 // for the original code and why this has been simplified 643 // with from-space allocation criteria modified and 644 // such allocation moved out of the safepoint path. 645 do_collection(true, // full 646 false, // clear_all_soft_refs 647 size, // size 648 is_tlab, // is_tlab 649 GenCollectedHeap::OldGen); // max_generation 650 } 651 652 result = attempt_allocation(size, is_tlab, false /*first_only*/); 653 654 if (result != nullptr) { 655 assert(is_in_reserved(result), "result not in heap"); 656 return result; 657 } 658 659 // OK, collection failed, try expansion. 660 result = expand_heap_and_allocate(size, is_tlab); 661 if (result != nullptr) { 662 return result; 663 } 664 665 // If we reach this point, we're really out of memory. Try every trick 666 // we can to reclaim memory. Force collection of soft references. Force 667 // a complete compaction of the heap. Any additional methods for finding 668 // free memory should be here, especially if they are expensive. If this 669 // attempt fails, an OOM exception will be thrown. 670 { 671 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted 672 673 do_collection(true, // full 674 true, // clear_all_soft_refs 675 size, // size 676 is_tlab, // is_tlab 677 GenCollectedHeap::OldGen); // max_generation 678 } 679 680 result = attempt_allocation(size, is_tlab, false /* first_only */); 681 if (result != nullptr) { 682 assert(is_in_reserved(result), "result not in heap"); 683 return result; 684 } 685 686 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 687 "Flag should have been handled and cleared prior to this point"); 688 689 // What else? We might try synchronous finalization later. If the total 690 // space available is large enough for the allocation, then a more 691 // complete compaction phase than we've tried so far might be 692 // appropriate. 693 return nullptr; 694 } 695 696 #ifdef ASSERT 697 class AssertNonScavengableClosure: public OopClosure { 698 public: 699 virtual void do_oop(oop* p) { 700 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 701 "Referent should not be scavengable."); } 702 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 703 }; 704 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 705 #endif 706 707 void GenCollectedHeap::process_roots(ScanningOption so, 708 OopClosure* strong_roots, 709 CLDClosure* strong_cld_closure, 710 CLDClosure* weak_cld_closure, 711 CodeBlobToOopClosure* code_roots) { 712 // General roots. 713 assert(code_roots != nullptr, "code root closure should always be set"); 714 715 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 716 717 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 718 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? nullptr : code_roots; 719 720 Threads::oops_do(strong_roots, roots_from_code_p); 721 722 OopStorageSet::strong_oops_do(strong_roots); 723 724 if (so & SO_ScavengeCodeCache) { 725 assert(code_roots != nullptr, "must supply closure for code cache"); 726 727 // We only visit parts of the CodeCache when scavenging. 728 ScavengableNMethods::nmethods_do(code_roots); 729 } 730 if (so & SO_AllCodeCache) { 731 assert(code_roots != nullptr, "must supply closure for code cache"); 732 733 // CMSCollector uses this to do intermediate-strength collections. 734 // We scan the entire code cache, since CodeCache::do_unloading is not called. 735 CodeCache::blobs_do(code_roots); 736 } 737 // Verify that the code cache contents are not subject to 738 // movement by a scavenging collection. 739 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 740 DEBUG_ONLY(ScavengableNMethods::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 741 } 742 743 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 744 WeakProcessor::oops_do(root_closure); 745 } 746 747 bool GenCollectedHeap::no_allocs_since_save_marks() { 748 return _young_gen->no_allocs_since_save_marks() && 749 _old_gen->no_allocs_since_save_marks(); 750 } 751 752 // public collection interfaces 753 void GenCollectedHeap::collect(GCCause::Cause cause) { 754 // The caller doesn't have the Heap_lock 755 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 756 757 unsigned int gc_count_before; 758 unsigned int full_gc_count_before; 759 760 { 761 MutexLocker ml(Heap_lock); 762 // Read the GC count while holding the Heap_lock 763 gc_count_before = total_collections(); 764 full_gc_count_before = total_full_collections(); 765 } 766 767 if (GCLocker::should_discard(cause, gc_count_before)) { 768 return; 769 } 770 771 bool should_run_young_gc = (cause == GCCause::_wb_young_gc) 772 || (cause == GCCause::_gc_locker) 773 DEBUG_ONLY(|| (cause == GCCause::_scavenge_alot)); 774 775 const GenerationType max_generation = should_run_young_gc 776 ? YoungGen 777 : OldGen; 778 779 while (true) { 780 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 781 cause, max_generation); 782 VMThread::execute(&op); 783 784 if (!GCCause::is_explicit_full_gc(cause)) { 785 return; 786 } 787 788 { 789 MutexLocker ml(Heap_lock); 790 // Read the GC count while holding the Heap_lock 791 if (full_gc_count_before != total_full_collections()) { 792 return; 793 } 794 } 795 796 if (GCLocker::is_active_and_needs_gc()) { 797 // If GCLocker is active, wait until clear before retrying. 798 GCLocker::stall_until_clear(); 799 } 800 } 801 } 802 803 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 804 do_full_collection(clear_all_soft_refs, OldGen); 805 } 806 807 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 808 GenerationType last_generation) { 809 do_collection(true, // full 810 clear_all_soft_refs, // clear_all_soft_refs 811 0, // size 812 false, // is_tlab 813 last_generation); // last_generation 814 // Hack XXX FIX ME !!! 815 // A scavenge may not have been attempted, or may have 816 // been attempted and failed, because the old gen was too full 817 if (gc_cause() == GCCause::_gc_locker && incremental_collection_failed()) { 818 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 819 // This time allow the old gen to be collected as well 820 do_collection(true, // full 821 clear_all_soft_refs, // clear_all_soft_refs 822 0, // size 823 false, // is_tlab 824 OldGen); // last_generation 825 } 826 } 827 828 bool GenCollectedHeap::is_in_young(const void* p) const { 829 bool result = p < _old_gen->reserved().start(); 830 assert(result == _young_gen->is_in_reserved(p), 831 "incorrect test - result=%d, p=" PTR_FORMAT, result, p2i(p)); 832 return result; 833 } 834 835 bool GenCollectedHeap::requires_barriers(stackChunkOop obj) const { 836 return !is_in_young(obj); 837 } 838 839 // Returns "TRUE" iff "p" points into the committed areas of the heap. 840 bool GenCollectedHeap::is_in(const void* p) const { 841 return _young_gen->is_in(p) || _old_gen->is_in(p); 842 } 843 844 #ifdef ASSERT 845 // Don't implement this by using is_in_young(). This method is used 846 // in some cases to check that is_in_young() is correct. 847 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 848 assert(is_in_reserved(p) || p == nullptr, 849 "Does not work if address is non-null and outside of the heap"); 850 return p < _young_gen->reserved().end() && p != nullptr; 851 } 852 #endif 853 854 void GenCollectedHeap::oop_iterate(OopIterateClosure* cl) { 855 _young_gen->oop_iterate(cl); 856 _old_gen->oop_iterate(cl); 857 } 858 859 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 860 _young_gen->object_iterate(cl); 861 _old_gen->object_iterate(cl); 862 } 863 864 Space* GenCollectedHeap::space_containing(const void* addr) const { 865 Space* res = _young_gen->space_containing(addr); 866 if (res != nullptr) { 867 return res; 868 } 869 res = _old_gen->space_containing(addr); 870 assert(res != nullptr, "Could not find containing space"); 871 return res; 872 } 873 874 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 875 assert(is_in_reserved(addr), "block_start of address outside of heap"); 876 if (_young_gen->is_in_reserved(addr)) { 877 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 878 return _young_gen->block_start(addr); 879 } 880 881 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 882 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 883 return _old_gen->block_start(addr); 884 } 885 886 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 887 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 888 assert(block_start(addr) == addr, "addr must be a block start"); 889 if (_young_gen->is_in_reserved(addr)) { 890 return _young_gen->block_is_obj(addr); 891 } 892 893 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 894 return _old_gen->block_is_obj(addr); 895 } 896 897 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 898 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 899 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!"); 900 return _young_gen->tlab_capacity(); 901 } 902 903 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 904 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 905 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!"); 906 return _young_gen->tlab_used(); 907 } 908 909 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 910 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 911 assert(_young_gen->supports_tlab_allocation(), "Young gen doesn't support TLAB allocation?!"); 912 return _young_gen->unsafe_max_tlab_alloc(); 913 } 914 915 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t min_size, 916 size_t requested_size, 917 size_t* actual_size) { 918 HeapWord* result = mem_allocate_work(requested_size /* size */, 919 true /* is_tlab */); 920 if (result != nullptr) { 921 *actual_size = requested_size; 922 } 923 924 return result; 925 } 926 927 // Requires "*prev_ptr" to be non-null. Deletes and a block of minimal size 928 // from the list headed by "*prev_ptr". 929 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 930 bool first = true; 931 size_t min_size = 0; // "first" makes this conceptually infinite. 932 ScratchBlock **smallest_ptr, *smallest; 933 ScratchBlock *cur = *prev_ptr; 934 while (cur) { 935 assert(*prev_ptr == cur, "just checking"); 936 if (first || cur->num_words < min_size) { 937 smallest_ptr = prev_ptr; 938 smallest = cur; 939 min_size = smallest->num_words; 940 first = false; 941 } 942 prev_ptr = &cur->next; 943 cur = cur->next; 944 } 945 smallest = *smallest_ptr; 946 *smallest_ptr = smallest->next; 947 return smallest; 948 } 949 950 // Sort the scratch block list headed by res into decreasing size order, 951 // and set "res" to the result. 952 static void sort_scratch_list(ScratchBlock*& list) { 953 ScratchBlock* sorted = nullptr; 954 ScratchBlock* unsorted = list; 955 while (unsorted) { 956 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 957 smallest->next = sorted; 958 sorted = smallest; 959 } 960 list = sorted; 961 } 962 963 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 964 size_t max_alloc_words) { 965 ScratchBlock* res = nullptr; 966 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 967 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 968 sort_scratch_list(res); 969 return res; 970 } 971 972 void GenCollectedHeap::release_scratch() { 973 _young_gen->reset_scratch(); 974 _old_gen->reset_scratch(); 975 } 976 977 void GenCollectedHeap::prepare_for_verify() { 978 ensure_parsability(false); // no need to retire TLABs 979 } 980 981 void GenCollectedHeap::generation_iterate(GenClosure* cl, 982 bool old_to_young) { 983 if (old_to_young) { 984 cl->do_generation(_old_gen); 985 cl->do_generation(_young_gen); 986 } else { 987 cl->do_generation(_young_gen); 988 cl->do_generation(_old_gen); 989 } 990 } 991 992 bool GenCollectedHeap::is_maximal_no_gc() const { 993 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 994 } 995 996 void GenCollectedHeap::save_marks() { 997 _young_gen->save_marks(); 998 _old_gen->save_marks(); 999 } 1000 1001 GenCollectedHeap* GenCollectedHeap::heap() { 1002 // SerialHeap is the only subtype of GenCollectedHeap. 1003 return named_heap<GenCollectedHeap>(CollectedHeap::Serial); 1004 } 1005 1006 #if INCLUDE_SERIALGC 1007 void GenCollectedHeap::prepare_for_compaction() { 1008 // Start by compacting into same gen. 1009 CompactPoint cp(_old_gen); 1010 _old_gen->prepare_for_compaction(&cp); 1011 _young_gen->prepare_for_compaction(&cp); 1012 } 1013 #endif // INCLUDE_SERIALGC 1014 1015 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1016 log_debug(gc, verify)("%s", _old_gen->name()); 1017 _old_gen->verify(); 1018 1019 log_debug(gc, verify)("%s", _young_gen->name()); 1020 _young_gen->verify(); 1021 1022 log_debug(gc, verify)("RemSet"); 1023 rem_set()->verify(); 1024 } 1025 1026 void GenCollectedHeap::print_on(outputStream* st) const { 1027 if (_young_gen != nullptr) { 1028 _young_gen->print_on(st); 1029 } 1030 if (_old_gen != nullptr) { 1031 _old_gen->print_on(st); 1032 } 1033 MetaspaceUtils::print_on(st); 1034 } 1035 1036 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1037 } 1038 1039 bool GenCollectedHeap::print_location(outputStream* st, void* addr) const { 1040 return BlockLocationPrinter<GenCollectedHeap>::print_location(st, addr); 1041 } 1042 1043 void GenCollectedHeap::print_tracing_info() const { 1044 if (log_is_enabled(Debug, gc, heap, exit)) { 1045 LogStreamHandle(Debug, gc, heap, exit) lsh; 1046 _young_gen->print_summary_info_on(&lsh); 1047 _old_gen->print_summary_info_on(&lsh); 1048 } 1049 } 1050 1051 void GenCollectedHeap::print_heap_change(const PreGenGCValues& pre_gc_values) const { 1052 const DefNewGeneration* const def_new_gen = (DefNewGeneration*) young_gen(); 1053 1054 log_info(gc, heap)(HEAP_CHANGE_FORMAT" " 1055 HEAP_CHANGE_FORMAT" " 1056 HEAP_CHANGE_FORMAT, 1057 HEAP_CHANGE_FORMAT_ARGS(def_new_gen->short_name(), 1058 pre_gc_values.young_gen_used(), 1059 pre_gc_values.young_gen_capacity(), 1060 def_new_gen->used(), 1061 def_new_gen->capacity()), 1062 HEAP_CHANGE_FORMAT_ARGS("Eden", 1063 pre_gc_values.eden_used(), 1064 pre_gc_values.eden_capacity(), 1065 def_new_gen->eden()->used(), 1066 def_new_gen->eden()->capacity()), 1067 HEAP_CHANGE_FORMAT_ARGS("From", 1068 pre_gc_values.from_used(), 1069 pre_gc_values.from_capacity(), 1070 def_new_gen->from()->used(), 1071 def_new_gen->from()->capacity())); 1072 log_info(gc, heap)(HEAP_CHANGE_FORMAT, 1073 HEAP_CHANGE_FORMAT_ARGS(old_gen()->short_name(), 1074 pre_gc_values.old_gen_used(), 1075 pre_gc_values.old_gen_capacity(), 1076 old_gen()->used(), 1077 old_gen()->capacity())); 1078 MetaspaceUtils::print_metaspace_change(pre_gc_values.metaspace_sizes()); 1079 } 1080 1081 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1082 private: 1083 bool _full; 1084 public: 1085 void do_generation(Generation* gen) { 1086 gen->gc_prologue(_full); 1087 } 1088 GenGCPrologueClosure(bool full) : _full(full) {}; 1089 }; 1090 1091 void GenCollectedHeap::gc_prologue(bool full) { 1092 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1093 1094 // Fill TLAB's and such 1095 ensure_parsability(true); // retire TLABs 1096 1097 // Walk generations 1098 GenGCPrologueClosure blk(full); 1099 generation_iterate(&blk, false); // not old-to-young. 1100 }; 1101 1102 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1103 private: 1104 bool _full; 1105 public: 1106 void do_generation(Generation* gen) { 1107 gen->gc_epilogue(_full); 1108 } 1109 GenGCEpilogueClosure(bool full) : _full(full) {}; 1110 }; 1111 1112 void GenCollectedHeap::gc_epilogue(bool full) { 1113 #if COMPILER2_OR_JVMCI 1114 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1115 #endif // COMPILER2_OR_JVMCI 1116 1117 resize_all_tlabs(); 1118 1119 GenGCEpilogueClosure blk(full); 1120 generation_iterate(&blk, false); // not old-to-young. 1121 1122 MetaspaceCounters::update_performance_counters(); 1123 }; 1124 1125 #ifndef PRODUCT 1126 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1127 private: 1128 public: 1129 void do_generation(Generation* gen) { 1130 gen->record_spaces_top(); 1131 } 1132 }; 1133 1134 void GenCollectedHeap::record_gen_tops_before_GC() { 1135 if (ZapUnusedHeapArea) { 1136 GenGCSaveTopsBeforeGCClosure blk; 1137 generation_iterate(&blk, false); // not old-to-young. 1138 } 1139 } 1140 #endif // not PRODUCT 1141 1142 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1143 public: 1144 void do_generation(Generation* gen) { 1145 gen->ensure_parsability(); 1146 } 1147 }; 1148 1149 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1150 CollectedHeap::ensure_parsability(retire_tlabs); 1151 GenEnsureParsabilityClosure ep_cl; 1152 generation_iterate(&ep_cl, false); 1153 } --- EOF ---