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/cardTableRS.hpp" 35 #include "gc/shared/collectedHeap.inline.hpp" 36 #include "gc/shared/collectorCounters.hpp" 37 #include "gc/shared/gcId.hpp" 38 #include "gc/shared/gcLocker.inline.hpp" 39 #include "gc/shared/gcTrace.hpp" 40 #include "gc/shared/gcTraceTime.inline.hpp" 41 #include "gc/shared/genCollectedHeap.hpp" 42 #include "gc/shared/genOopClosures.inline.hpp" 43 #include "gc/shared/generationSpec.hpp" 44 #include "gc/shared/space.hpp" 45 #include "gc/shared/strongRootsScope.hpp" 46 #include "gc/shared/vmGCOperations.hpp" 47 #include "gc/shared/weakProcessor.hpp" 48 #include "gc/shared/workgroup.hpp" 49 #include "memory/filemap.hpp" 50 #include "memory/resourceArea.hpp" 51 #include "oops/oop.inline.hpp" 52 #include "runtime/biasedLocking.hpp" 53 #include "runtime/handles.hpp" 54 #include "runtime/handles.inline.hpp" 55 #include "runtime/java.hpp" 56 #include "runtime/vmThread.hpp" 57 #include "services/management.hpp" 58 #include "services/memoryService.hpp" 59 #include "utilities/debug.hpp" 60 #include "utilities/formatBuffer.hpp" 61 #include "utilities/macros.hpp" 62 #include "utilities/stack.inline.hpp" 63 #include "utilities/vmError.hpp" 64 65 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy, 66 Generation::Name young, 67 Generation::Name old) : 68 CollectedHeap(), 69 _rem_set(NULL), 70 _young_gen_spec(new GenerationSpec(young, 71 policy->initial_young_size(), 72 policy->max_young_size(), 73 policy->gen_alignment())), 74 _old_gen_spec(new GenerationSpec(old, 75 policy->initial_old_size(), 76 policy->max_old_size(), 77 policy->gen_alignment())), 78 _gen_policy(policy), 79 _soft_ref_gen_policy(), 80 _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)), 81 _full_collections_completed(0) { 82 } 83 84 jint GenCollectedHeap::initialize() { 85 // While there are no constraints in the GC code that HeapWordSize 86 // be any particular value, there are multiple other areas in the 87 // system which believe this to be true (e.g. oop->object_size in some 88 // cases incorrectly returns the size in wordSize units rather than 89 // HeapWordSize). 90 guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize"); 91 92 // Allocate space for the heap. 93 94 char* heap_address; 95 ReservedSpace heap_rs; 96 97 size_t heap_alignment = collector_policy()->heap_alignment(); 98 99 heap_address = allocate(heap_alignment, &heap_rs); 100 101 if (!heap_rs.is_reserved()) { 102 vm_shutdown_during_initialization( 103 "Could not reserve enough space for object heap"); 104 return JNI_ENOMEM; 105 } 106 107 initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size())); 108 109 _rem_set = new CardTableRS(reserved_region()); 110 set_barrier_set(rem_set()->bs()); 111 112 ReservedSpace young_rs = heap_rs.first_part(young_gen_spec()->max_size(), false, false); 113 _young_gen = young_gen_spec()->init(young_rs, rem_set()); 114 heap_rs = heap_rs.last_part(young_gen_spec()->max_size()); 115 116 ReservedSpace old_rs = heap_rs.first_part(old_gen_spec()->max_size(), false, false); 117 _old_gen = old_gen_spec()->init(old_rs, rem_set()); 118 clear_incremental_collection_failed(); 119 120 return JNI_OK; 121 } 122 123 void GenCollectedHeap::initialize_generations(Generation::Name young, 124 Generation::Name old) { 125 } 126 127 void GenCollectedHeap::initialize_size_policy(size_t init_eden_size, 128 size_t init_promo_size, 129 size_t init_survivor_size) { 130 const double max_gc_pause_sec = ((double) MaxGCPauseMillis) / 1000.0; 131 _size_policy = new AdaptiveSizePolicy(init_eden_size, 132 init_promo_size, 133 init_survivor_size, 134 max_gc_pause_sec, 135 GCTimeRatio); 136 } 137 138 char* GenCollectedHeap::allocate(size_t alignment, 139 ReservedSpace* heap_rs){ 140 // Now figure out the total size. 141 const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size(); 142 assert(alignment % pageSize == 0, "Must be"); 143 144 GenerationSpec* young_spec = young_gen_spec(); 145 GenerationSpec* old_spec = old_gen_spec(); 146 147 // Check for overflow. 148 size_t total_reserved = young_spec->max_size() + old_spec->max_size(); 149 if (total_reserved < young_spec->max_size()) { 150 vm_exit_during_initialization("The size of the object heap + VM data exceeds " 151 "the maximum representable size"); 152 } 153 assert(total_reserved % alignment == 0, 154 "Gen size; total_reserved=" SIZE_FORMAT ", alignment=" 155 SIZE_FORMAT, total_reserved, alignment); 156 157 *heap_rs = Universe::reserve_heap(total_reserved, alignment); 158 159 os::trace_page_sizes("Heap", 160 collector_policy()->min_heap_byte_size(), 161 total_reserved, 162 alignment, 163 heap_rs->base(), 164 heap_rs->size()); 165 166 return heap_rs->base(); 167 } 168 169 void GenCollectedHeap::post_initialize() { 170 CollectedHeap::post_initialize(); 171 ref_processing_init(); 172 check_gen_kinds(); 173 DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen; 174 175 initialize_size_policy(def_new_gen->eden()->capacity(), 176 _old_gen->capacity(), 177 def_new_gen->from()->capacity()); 178 179 _gen_policy->initialize_gc_policy_counters(); 180 } 181 182 void GenCollectedHeap::ref_processing_init() { 183 _young_gen->ref_processor_init(); 184 _old_gen->ref_processor_init(); 185 } 186 187 GenerationSpec* GenCollectedHeap::young_gen_spec() const { 188 assert(_young_gen_spec != NULL, "_young_gen_spec should have been initialized"); 189 return _young_gen_spec; 190 } 191 192 GenerationSpec* GenCollectedHeap::old_gen_spec() const { 193 assert(_old_gen_spec != NULL, "_old_gen_spec should have been initialized"); 194 return _old_gen_spec; 195 } 196 197 size_t GenCollectedHeap::capacity() const { 198 return _young_gen->capacity() + _old_gen->capacity(); 199 } 200 201 size_t GenCollectedHeap::used() const { 202 return _young_gen->used() + _old_gen->used(); 203 } 204 205 void GenCollectedHeap::save_used_regions() { 206 _old_gen->save_used_region(); 207 _young_gen->save_used_region(); 208 } 209 210 size_t GenCollectedHeap::max_capacity() const { 211 return _young_gen->max_capacity() + _old_gen->max_capacity(); 212 } 213 214 // Update the _full_collections_completed counter 215 // at the end of a stop-world full GC. 216 unsigned int GenCollectedHeap::update_full_collections_completed() { 217 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 218 assert(_full_collections_completed <= _total_full_collections, 219 "Can't complete more collections than were started"); 220 _full_collections_completed = _total_full_collections; 221 ml.notify_all(); 222 return _full_collections_completed; 223 } 224 225 // Update the _full_collections_completed counter, as appropriate, 226 // at the end of a concurrent GC cycle. Note the conditional update 227 // below to allow this method to be called by a concurrent collector 228 // without synchronizing in any manner with the VM thread (which 229 // may already have initiated a STW full collection "concurrently"). 230 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) { 231 MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag); 232 assert((_full_collections_completed <= _total_full_collections) && 233 (count <= _total_full_collections), 234 "Can't complete more collections than were started"); 235 if (count > _full_collections_completed) { 236 _full_collections_completed = count; 237 ml.notify_all(); 238 } 239 return _full_collections_completed; 240 } 241 242 // Return true if any of the following is true: 243 // . the allocation won't fit into the current young gen heap 244 // . gc locker is occupied (jni critical section) 245 // . heap memory is tight -- the most recent previous collection 246 // was a full collection because a partial collection (would 247 // have) failed and is likely to fail again 248 bool GenCollectedHeap::should_try_older_generation_allocation(size_t word_size) const { 249 size_t young_capacity = young_gen()->capacity_before_gc(); 250 return (word_size > heap_word_size(young_capacity)) 251 || GCLocker::is_active_and_needs_gc() 252 || incremental_collection_failed(); 253 } 254 255 HeapWord* GenCollectedHeap::expand_heap_and_allocate(size_t size, bool is_tlab) { 256 HeapWord* result = NULL; 257 if (old_gen()->should_allocate(size, is_tlab)) { 258 result = old_gen()->expand_and_allocate(size, is_tlab); 259 } 260 if (result == NULL) { 261 if (young_gen()->should_allocate(size, is_tlab)) { 262 result = young_gen()->expand_and_allocate(size, is_tlab); 263 } 264 } 265 assert(result == NULL || is_in_reserved(result), "result not in heap"); 266 return result; 267 } 268 269 HeapWord* GenCollectedHeap::mem_allocate_work(size_t size, 270 bool is_tlab, 271 bool* gc_overhead_limit_was_exceeded) { 272 debug_only(check_for_valid_allocation_state()); 273 assert(no_gc_in_progress(), "Allocation during gc not allowed"); 274 275 // In general gc_overhead_limit_was_exceeded should be false so 276 // set it so here and reset it to true only if the gc time 277 // limit is being exceeded as checked below. 278 *gc_overhead_limit_was_exceeded = false; 279 280 HeapWord* result = NULL; 281 282 // Loop until the allocation is satisfied, or unsatisfied after GC. 283 for (uint try_count = 1, gclocker_stalled_count = 0; /* return or throw */; try_count += 1) { 284 HandleMark hm; // Discard any handles allocated in each iteration. 285 286 // First allocation attempt is lock-free. 287 Generation *young = young_gen(); 288 assert(young->supports_inline_contig_alloc(), 289 "Otherwise, must do alloc within heap lock"); 290 if (young->should_allocate(size, is_tlab)) { 291 result = young->par_allocate(size, is_tlab); 292 if (result != NULL) { 293 assert(is_in_reserved(result), "result not in heap"); 294 return result; 295 } 296 } 297 uint gc_count_before; // Read inside the Heap_lock locked region. 298 { 299 MutexLocker ml(Heap_lock); 300 log_trace(gc, alloc)("GenCollectedHeap::mem_allocate_work: attempting locked slow path allocation"); 301 // Note that only large objects get a shot at being 302 // allocated in later generations. 303 bool first_only = !should_try_older_generation_allocation(size); 304 305 result = attempt_allocation(size, is_tlab, first_only); 306 if (result != NULL) { 307 assert(is_in_reserved(result), "result not in heap"); 308 return result; 309 } 310 311 if (GCLocker::is_active_and_needs_gc()) { 312 if (is_tlab) { 313 return NULL; // Caller will retry allocating individual object. 314 } 315 if (!is_maximal_no_gc()) { 316 // Try and expand heap to satisfy request. 317 result = expand_heap_and_allocate(size, is_tlab); 318 // Result could be null if we are out of space. 319 if (result != NULL) { 320 return result; 321 } 322 } 323 324 if (gclocker_stalled_count > GCLockerRetryAllocationCount) { 325 return NULL; // We didn't get to do a GC and we didn't get any memory. 326 } 327 328 // If this thread is not in a jni critical section, we stall 329 // the requestor until the critical section has cleared and 330 // GC allowed. When the critical section clears, a GC is 331 // initiated by the last thread exiting the critical section; so 332 // we retry the allocation sequence from the beginning of the loop, 333 // rather than causing more, now probably unnecessary, GC attempts. 334 JavaThread* jthr = JavaThread::current(); 335 if (!jthr->in_critical()) { 336 MutexUnlocker mul(Heap_lock); 337 // Wait for JNI critical section to be exited 338 GCLocker::stall_until_clear(); 339 gclocker_stalled_count += 1; 340 continue; 341 } else { 342 if (CheckJNICalls) { 343 fatal("Possible deadlock due to allocating while" 344 " in jni critical section"); 345 } 346 return NULL; 347 } 348 } 349 350 // Read the gc count while the heap lock is held. 351 gc_count_before = total_collections(); 352 } 353 354 VM_GenCollectForAllocation op(size, is_tlab, gc_count_before); 355 VMThread::execute(&op); 356 if (op.prologue_succeeded()) { 357 result = op.result(); 358 if (op.gc_locked()) { 359 assert(result == NULL, "must be NULL if gc_locked() is true"); 360 continue; // Retry and/or stall as necessary. 361 } 362 363 // Allocation has failed and a collection 364 // has been done. If the gc time limit was exceeded the 365 // this time, return NULL so that an out-of-memory 366 // will be thrown. Clear gc_overhead_limit_exceeded 367 // so that the overhead exceeded does not persist. 368 369 const bool limit_exceeded = size_policy()->gc_overhead_limit_exceeded(); 370 const bool softrefs_clear = soft_ref_policy()->all_soft_refs_clear(); 371 372 if (limit_exceeded && softrefs_clear) { 373 *gc_overhead_limit_was_exceeded = true; 374 size_policy()->set_gc_overhead_limit_exceeded(false); 375 if (op.result() != NULL) { 376 CollectedHeap::fill_with_object(op.result(), size); 377 } 378 return NULL; 379 } 380 assert(result == NULL || is_in_reserved(result), 381 "result not in heap"); 382 return result; 383 } 384 385 // Give a warning if we seem to be looping forever. 386 if ((QueuedAllocationWarningCount > 0) && 387 (try_count % QueuedAllocationWarningCount == 0)) { 388 log_warning(gc, ergo)("GenCollectedHeap::mem_allocate_work retries %d times," 389 " size=" SIZE_FORMAT " %s", try_count, size, is_tlab ? "(TLAB)" : ""); 390 } 391 } 392 } 393 394 #ifndef PRODUCT 395 // Override of memory state checking method in CollectedHeap: 396 // Some collectors (CMS for example) can't have badHeapWordVal written 397 // in the first two words of an object. (For instance , in the case of 398 // CMS these words hold state used to synchronize between certain 399 // (concurrent) GC steps and direct allocating mutators.) 400 // The skip_header_HeapWords() method below, allows us to skip 401 // over the requisite number of HeapWord's. Note that (for 402 // generational collectors) this means that those many words are 403 // skipped in each object, irrespective of the generation in which 404 // that object lives. The resultant loss of precision seems to be 405 // harmless and the pain of avoiding that imprecision appears somewhat 406 // higher than we are prepared to pay for such rudimentary debugging 407 // support. 408 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr, 409 size_t size) { 410 if (CheckMemoryInitialization && ZapUnusedHeapArea) { 411 // We are asked to check a size in HeapWords, 412 // but the memory is mangled in juint words. 413 juint* start = (juint*) (addr + skip_header_HeapWords()); 414 juint* end = (juint*) (addr + size); 415 for (juint* slot = start; slot < end; slot += 1) { 416 assert(*slot == badHeapWordVal, 417 "Found non badHeapWordValue in pre-allocation check"); 418 } 419 } 420 } 421 #endif 422 423 HeapWord* GenCollectedHeap::attempt_allocation(size_t size, 424 bool is_tlab, 425 bool first_only) { 426 HeapWord* res = NULL; 427 428 if (_young_gen->should_allocate(size, is_tlab)) { 429 res = _young_gen->allocate(size, is_tlab); 430 if (res != NULL || first_only) { 431 return res; 432 } 433 } 434 435 if (_old_gen->should_allocate(size, is_tlab)) { 436 res = _old_gen->allocate(size, is_tlab); 437 } 438 439 return res; 440 } 441 442 HeapWord* GenCollectedHeap::mem_allocate(size_t size, 443 bool* gc_overhead_limit_was_exceeded) { 444 return mem_allocate_work(size, 445 false /* is_tlab */, 446 gc_overhead_limit_was_exceeded); 447 } 448 449 bool GenCollectedHeap::must_clear_all_soft_refs() { 450 return _gc_cause == GCCause::_metadata_GC_clear_soft_refs || 451 _gc_cause == GCCause::_wb_full_gc; 452 } 453 454 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size, 455 bool is_tlab, bool run_verification, bool clear_soft_refs, 456 bool restore_marks_for_biased_locking) { 457 FormatBuffer<> title("Collect gen: %s", gen->short_name()); 458 GCTraceTime(Trace, gc, phases) t1(title); 459 TraceCollectorStats tcs(gen->counters()); 460 TraceMemoryManagerStats tmms(gen->gc_manager(), gc_cause()); 461 462 gen->stat_record()->invocations++; 463 gen->stat_record()->accumulated_time.start(); 464 465 // Must be done anew before each collection because 466 // a previous collection will do mangling and will 467 // change top of some spaces. 468 record_gen_tops_before_GC(); 469 470 log_trace(gc)("%s invoke=%d size=" SIZE_FORMAT, heap()->is_young_gen(gen) ? "Young" : "Old", gen->stat_record()->invocations, size * HeapWordSize); 471 472 if (run_verification && VerifyBeforeGC) { 473 HandleMark hm; // Discard invalid handles created during verification 474 Universe::verify("Before GC"); 475 } 476 COMPILER2_PRESENT(DerivedPointerTable::clear()); 477 478 if (restore_marks_for_biased_locking) { 479 // We perform this mark word preservation work lazily 480 // because it's only at this point that we know whether we 481 // absolutely have to do it; we want to avoid doing it for 482 // scavenge-only collections where it's unnecessary 483 BiasedLocking::preserve_marks(); 484 } 485 486 // Do collection work 487 { 488 // Note on ref discovery: For what appear to be historical reasons, 489 // GCH enables and disabled (by enqueing) refs discovery. 490 // In the future this should be moved into the generation's 491 // collect method so that ref discovery and enqueueing concerns 492 // are local to a generation. The collect method could return 493 // an appropriate indication in the case that notification on 494 // the ref lock was needed. This will make the treatment of 495 // weak refs more uniform (and indeed remove such concerns 496 // from GCH). XXX 497 498 HandleMark hm; // Discard invalid handles created during gc 499 save_marks(); // save marks for all gens 500 // We want to discover references, but not process them yet. 501 // This mode is disabled in process_discovered_references if the 502 // generation does some collection work, or in 503 // enqueue_discovered_references if the generation returns 504 // without doing any work. 505 ReferenceProcessor* rp = gen->ref_processor(); 506 // If the discovery of ("weak") refs in this generation is 507 // atomic wrt other collectors in this configuration, we 508 // are guaranteed to have empty discovered ref lists. 509 if (rp->discovery_is_atomic()) { 510 rp->enable_discovery(); 511 rp->setup_policy(clear_soft_refs); 512 } else { 513 // collect() below will enable discovery as appropriate 514 } 515 gen->collect(full, clear_soft_refs, size, is_tlab); 516 if (!rp->enqueuing_is_done()) { 517 ReferenceProcessorPhaseTimes pt(NULL, rp->num_q()); 518 rp->enqueue_discovered_references(NULL, &pt); 519 pt.print_enqueue_phase(); 520 } else { 521 rp->set_enqueuing_is_done(false); 522 } 523 rp->verify_no_references_recorded(); 524 } 525 526 COMPILER2_PRESENT(DerivedPointerTable::update_pointers()); 527 528 gen->stat_record()->accumulated_time.stop(); 529 530 update_gc_stats(gen, full); 531 532 if (run_verification && VerifyAfterGC) { 533 HandleMark hm; // Discard invalid handles created during verification 534 Universe::verify("After GC"); 535 } 536 } 537 538 void GenCollectedHeap::do_collection(bool full, 539 bool clear_all_soft_refs, 540 size_t size, 541 bool is_tlab, 542 GenerationType max_generation) { 543 ResourceMark rm; 544 DEBUG_ONLY(Thread* my_thread = Thread::current();) 545 546 assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint"); 547 assert(my_thread->is_VM_thread() || 548 my_thread->is_ConcurrentGC_thread(), 549 "incorrect thread type capability"); 550 assert(Heap_lock->is_locked(), 551 "the requesting thread should have the Heap_lock"); 552 guarantee(!is_gc_active(), "collection is not reentrant"); 553 554 if (GCLocker::check_active_before_gc()) { 555 return; // GC is disabled (e.g. JNI GetXXXCritical operation) 556 } 557 558 GCIdMark gc_id_mark; 559 560 const bool do_clear_all_soft_refs = clear_all_soft_refs || 561 soft_ref_policy()->should_clear_all_soft_refs(); 562 563 ClearedAllSoftRefs casr(do_clear_all_soft_refs, soft_ref_policy()); 564 565 const size_t metadata_prev_used = MetaspaceAux::used_bytes(); 566 567 print_heap_before_gc(); 568 569 { 570 FlagSetting fl(_is_gc_active, true); 571 572 bool complete = full && (max_generation == OldGen); 573 bool old_collects_young = complete && !ScavengeBeforeFullGC; 574 bool do_young_collection = !old_collects_young && _young_gen->should_collect(full, size, is_tlab); 575 576 FormatBuffer<> gc_string("%s", "Pause "); 577 if (do_young_collection) { 578 gc_string.append("Young"); 579 } else { 580 gc_string.append("Full"); 581 } 582 583 GCTraceCPUTime tcpu; 584 GCTraceTime(Info, gc) t(gc_string, NULL, gc_cause(), true); 585 586 gc_prologue(complete); 587 increment_total_collections(complete); 588 589 size_t young_prev_used = _young_gen->used(); 590 size_t old_prev_used = _old_gen->used(); 591 592 bool run_verification = total_collections() >= VerifyGCStartAt; 593 594 bool prepared_for_verification = false; 595 bool collected_old = false; 596 597 if (do_young_collection) { 598 if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) { 599 prepare_for_verify(); 600 prepared_for_verification = true; 601 } 602 603 collect_generation(_young_gen, 604 full, 605 size, 606 is_tlab, 607 run_verification && VerifyGCLevel <= 0, 608 do_clear_all_soft_refs, 609 false); 610 611 if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) && 612 size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) { 613 // Allocation request was met by young GC. 614 size = 0; 615 } 616 } 617 618 bool must_restore_marks_for_biased_locking = false; 619 620 if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) { 621 if (!complete) { 622 // The full_collections increment was missed above. 623 increment_total_full_collections(); 624 } 625 626 if (!prepared_for_verification && run_verification && 627 VerifyGCLevel <= 1 && VerifyBeforeGC) { 628 prepare_for_verify(); 629 } 630 631 if (do_young_collection) { 632 // We did a young GC. Need a new GC id for the old GC. 633 GCIdMark gc_id_mark; 634 GCTraceTime(Info, gc) t("Pause Full", NULL, gc_cause(), true); 635 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 636 } else { 637 // No young GC done. Use the same GC id as was set up earlier in this method. 638 collect_generation(_old_gen, full, size, is_tlab, run_verification && VerifyGCLevel <= 1, do_clear_all_soft_refs, true); 639 } 640 641 must_restore_marks_for_biased_locking = true; 642 collected_old = true; 643 } 644 645 // Update "complete" boolean wrt what actually transpired -- 646 // for instance, a promotion failure could have led to 647 // a whole heap collection. 648 complete = complete || collected_old; 649 650 print_heap_change(young_prev_used, old_prev_used); 651 MetaspaceAux::print_metaspace_change(metadata_prev_used); 652 653 // Adjust generation sizes. 654 if (collected_old) { 655 _old_gen->compute_new_size(); 656 } 657 _young_gen->compute_new_size(); 658 659 if (complete) { 660 // Delete metaspaces for unloaded class loaders and clean up loader_data graph 661 ClassLoaderDataGraph::purge(); 662 MetaspaceAux::verify_metrics(); 663 // Resize the metaspace capacity after full collections 664 MetaspaceGC::compute_new_size(); 665 update_full_collections_completed(); 666 } 667 668 // Track memory usage and detect low memory after GC finishes 669 MemoryService::track_memory_usage(); 670 671 gc_epilogue(complete); 672 673 if (must_restore_marks_for_biased_locking) { 674 BiasedLocking::restore_marks(); 675 } 676 } 677 678 print_heap_after_gc(); 679 680 #ifdef TRACESPINNING 681 ParallelTaskTerminator::print_termination_counts(); 682 #endif 683 } 684 685 void GenCollectedHeap::register_nmethod(nmethod* nm) { 686 CodeCache::register_scavenge_root_nmethod(nm); 687 } 688 689 void GenCollectedHeap::verify_nmethod(nmethod* nm) { 690 CodeCache::verify_scavenge_root_nmethod(nm); 691 } 692 693 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) { 694 GCCauseSetter x(this, GCCause::_allocation_failure); 695 HeapWord* result = NULL; 696 697 assert(size != 0, "Precondition violated"); 698 if (GCLocker::is_active_and_needs_gc()) { 699 // GC locker is active; instead of a collection we will attempt 700 // to expand the heap, if there's room for expansion. 701 if (!is_maximal_no_gc()) { 702 result = expand_heap_and_allocate(size, is_tlab); 703 } 704 return result; // Could be null if we are out of space. 705 } else if (!incremental_collection_will_fail(false /* don't consult_young */)) { 706 // Do an incremental collection. 707 do_collection(false, // full 708 false, // clear_all_soft_refs 709 size, // size 710 is_tlab, // is_tlab 711 GenCollectedHeap::OldGen); // max_generation 712 } else { 713 log_trace(gc)(" :: Trying full because partial may fail :: "); 714 // Try a full collection; see delta for bug id 6266275 715 // for the original code and why this has been simplified 716 // with from-space allocation criteria modified and 717 // such allocation moved out of the safepoint path. 718 do_collection(true, // full 719 false, // clear_all_soft_refs 720 size, // size 721 is_tlab, // is_tlab 722 GenCollectedHeap::OldGen); // max_generation 723 } 724 725 result = attempt_allocation(size, is_tlab, false /*first_only*/); 726 727 if (result != NULL) { 728 assert(is_in_reserved(result), "result not in heap"); 729 return result; 730 } 731 732 // OK, collection failed, try expansion. 733 result = expand_heap_and_allocate(size, is_tlab); 734 if (result != NULL) { 735 return result; 736 } 737 738 // If we reach this point, we're really out of memory. Try every trick 739 // we can to reclaim memory. Force collection of soft references. Force 740 // a complete compaction of the heap. Any additional methods for finding 741 // free memory should be here, especially if they are expensive. If this 742 // attempt fails, an OOM exception will be thrown. 743 { 744 UIntFlagSetting flag_change(MarkSweepAlwaysCompactCount, 1); // Make sure the heap is fully compacted 745 746 do_collection(true, // full 747 true, // clear_all_soft_refs 748 size, // size 749 is_tlab, // is_tlab 750 GenCollectedHeap::OldGen); // max_generation 751 } 752 753 result = attempt_allocation(size, is_tlab, false /* first_only */); 754 if (result != NULL) { 755 assert(is_in_reserved(result), "result not in heap"); 756 return result; 757 } 758 759 assert(!soft_ref_policy()->should_clear_all_soft_refs(), 760 "Flag should have been handled and cleared prior to this point"); 761 762 // What else? We might try synchronous finalization later. If the total 763 // space available is large enough for the allocation, then a more 764 // complete compaction phase than we've tried so far might be 765 // appropriate. 766 return NULL; 767 } 768 769 #ifdef ASSERT 770 class AssertNonScavengableClosure: public OopClosure { 771 public: 772 virtual void do_oop(oop* p) { 773 assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p), 774 "Referent should not be scavengable."); } 775 virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); } 776 }; 777 static AssertNonScavengableClosure assert_is_non_scavengable_closure; 778 #endif 779 780 void GenCollectedHeap::process_roots(StrongRootsScope* scope, 781 ScanningOption so, 782 OopClosure* strong_roots, 783 OopClosure* weak_roots, 784 CLDClosure* strong_cld_closure, 785 CLDClosure* weak_cld_closure, 786 CodeBlobToOopClosure* code_roots) { 787 // General roots. 788 assert(Threads::thread_claim_parity() != 0, "must have called prologue code"); 789 assert(code_roots != NULL, "code root closure should always be set"); 790 // _n_termination for _process_strong_tasks should be set up stream 791 // in a method not running in a GC worker. Otherwise the GC worker 792 // could be trying to change the termination condition while the task 793 // is executing in another GC worker. 794 795 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) { 796 ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure); 797 } 798 799 // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway 800 CodeBlobToOopClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots; 801 802 bool is_par = scope->n_threads() > 1; 803 Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_code_p); 804 805 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) { 806 Universe::oops_do(strong_roots); 807 } 808 // Global (strong) JNI handles 809 if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) { 810 JNIHandles::oops_do(strong_roots); 811 } 812 813 if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) { 814 ObjectSynchronizer::oops_do(strong_roots); 815 } 816 if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) { 817 Management::oops_do(strong_roots); 818 } 819 if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) { 820 JvmtiExport::oops_do(strong_roots); 821 } 822 if (UseAOT && !_process_strong_tasks->is_task_claimed(GCH_PS_aot_oops_do)) { 823 AOTLoader::oops_do(strong_roots); 824 } 825 826 if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) { 827 SystemDictionary::roots_oops_do(strong_roots, weak_roots); 828 } 829 830 if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) { 831 if (so & SO_ScavengeCodeCache) { 832 assert(code_roots != NULL, "must supply closure for code cache"); 833 834 // We only visit parts of the CodeCache when scavenging. 835 CodeCache::scavenge_root_nmethods_do(code_roots); 836 } 837 if (so & SO_AllCodeCache) { 838 assert(code_roots != NULL, "must supply closure for code cache"); 839 840 // CMSCollector uses this to do intermediate-strength collections. 841 // We scan the entire code cache, since CodeCache::do_unloading is not called. 842 CodeCache::blobs_do(code_roots); 843 } 844 // Verify that the code cache contents are not subject to 845 // movement by a scavenging collection. 846 DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations)); 847 DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable)); 848 } 849 } 850 851 void GenCollectedHeap::process_string_table_roots(StrongRootsScope* scope, 852 OopClosure* root_closure) { 853 assert(root_closure != NULL, "Must be set"); 854 // All threads execute the following. A specific chunk of buckets 855 // from the StringTable are the individual tasks. 856 if (scope->n_threads() > 1) { 857 StringTable::possibly_parallel_oops_do(root_closure); 858 } else { 859 StringTable::oops_do(root_closure); 860 } 861 } 862 863 void GenCollectedHeap::young_process_roots(StrongRootsScope* scope, 864 OopsInGenClosure* root_closure, 865 OopsInGenClosure* old_gen_closure, 866 CLDClosure* cld_closure) { 867 MarkingCodeBlobClosure mark_code_closure(root_closure, CodeBlobToOopClosure::FixRelocations); 868 869 process_roots(scope, SO_ScavengeCodeCache, root_closure, root_closure, 870 cld_closure, cld_closure, &mark_code_closure); 871 process_string_table_roots(scope, root_closure); 872 873 if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) { 874 root_closure->reset_generation(); 875 } 876 877 // When collection is parallel, all threads get to cooperate to do 878 // old generation scanning. 879 old_gen_closure->set_generation(_old_gen); 880 rem_set()->younger_refs_iterate(_old_gen, old_gen_closure, scope->n_threads()); 881 old_gen_closure->reset_generation(); 882 883 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 884 } 885 886 void GenCollectedHeap::full_process_roots(StrongRootsScope* scope, 887 bool is_adjust_phase, 888 ScanningOption so, 889 bool only_strong_roots, 890 OopsInGenClosure* root_closure, 891 CLDClosure* cld_closure) { 892 MarkingCodeBlobClosure mark_code_closure(root_closure, is_adjust_phase); 893 OopsInGenClosure* weak_roots = only_strong_roots ? NULL : root_closure; 894 CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure; 895 896 process_roots(scope, so, root_closure, weak_roots, cld_closure, weak_cld_closure, &mark_code_closure); 897 if (is_adjust_phase) { 898 // We never treat the string table as roots during marking 899 // for the full gc, so we only need to process it during 900 // the adjust phase. 901 process_string_table_roots(scope, root_closure); 902 } 903 904 _process_strong_tasks->all_tasks_completed(scope->n_threads()); 905 } 906 907 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) { 908 WeakProcessor::oops_do(root_closure); 909 _young_gen->ref_processor()->weak_oops_do(root_closure); 910 _old_gen->ref_processor()->weak_oops_do(root_closure); 911 } 912 913 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix) \ 914 void GenCollectedHeap:: \ 915 oop_since_save_marks_iterate(GenerationType gen, \ 916 OopClosureType* cur, \ 917 OopClosureType* older) { \ 918 if (gen == YoungGen) { \ 919 _young_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 920 _old_gen->oop_since_save_marks_iterate##nv_suffix(older); \ 921 } else { \ 922 _old_gen->oop_since_save_marks_iterate##nv_suffix(cur); \ 923 } \ 924 } 925 926 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN) 927 928 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN 929 930 bool GenCollectedHeap::no_allocs_since_save_marks() { 931 return _young_gen->no_allocs_since_save_marks() && 932 _old_gen->no_allocs_since_save_marks(); 933 } 934 935 bool GenCollectedHeap::supports_inline_contig_alloc() const { 936 return _young_gen->supports_inline_contig_alloc(); 937 } 938 939 HeapWord* volatile* GenCollectedHeap::top_addr() const { 940 return _young_gen->top_addr(); 941 } 942 943 HeapWord** GenCollectedHeap::end_addr() const { 944 return _young_gen->end_addr(); 945 } 946 947 // public collection interfaces 948 949 void GenCollectedHeap::collect(GCCause::Cause cause) { 950 if (cause == GCCause::_wb_young_gc) { 951 // Young collection for the WhiteBox API. 952 collect(cause, YoungGen); 953 } else { 954 #ifdef ASSERT 955 if (cause == GCCause::_scavenge_alot) { 956 // Young collection only. 957 collect(cause, YoungGen); 958 } else { 959 // Stop-the-world full collection. 960 collect(cause, OldGen); 961 } 962 #else 963 // Stop-the-world full collection. 964 collect(cause, OldGen); 965 #endif 966 } 967 } 968 969 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) { 970 // The caller doesn't have the Heap_lock 971 assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock"); 972 MutexLocker ml(Heap_lock); 973 collect_locked(cause, max_generation); 974 } 975 976 void GenCollectedHeap::collect_locked(GCCause::Cause cause) { 977 // The caller has the Heap_lock 978 assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock"); 979 collect_locked(cause, OldGen); 980 } 981 982 // this is the private collection interface 983 // The Heap_lock is expected to be held on entry. 984 985 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) { 986 // Read the GC count while holding the Heap_lock 987 unsigned int gc_count_before = total_collections(); 988 unsigned int full_gc_count_before = total_full_collections(); 989 { 990 MutexUnlocker mu(Heap_lock); // give up heap lock, execute gets it back 991 VM_GenCollectFull op(gc_count_before, full_gc_count_before, 992 cause, max_generation); 993 VMThread::execute(&op); 994 } 995 } 996 997 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) { 998 do_full_collection(clear_all_soft_refs, OldGen); 999 } 1000 1001 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs, 1002 GenerationType last_generation) { 1003 GenerationType local_last_generation; 1004 if (!incremental_collection_will_fail(false /* don't consult_young */) && 1005 gc_cause() == GCCause::_gc_locker) { 1006 local_last_generation = YoungGen; 1007 } else { 1008 local_last_generation = last_generation; 1009 } 1010 1011 do_collection(true, // full 1012 clear_all_soft_refs, // clear_all_soft_refs 1013 0, // size 1014 false, // is_tlab 1015 local_last_generation); // last_generation 1016 // Hack XXX FIX ME !!! 1017 // A scavenge may not have been attempted, or may have 1018 // been attempted and failed, because the old gen was too full 1019 if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker && 1020 incremental_collection_will_fail(false /* don't consult_young */)) { 1021 log_debug(gc, jni)("GC locker: Trying a full collection because scavenge failed"); 1022 // This time allow the old gen to be collected as well 1023 do_collection(true, // full 1024 clear_all_soft_refs, // clear_all_soft_refs 1025 0, // size 1026 false, // is_tlab 1027 OldGen); // last_generation 1028 } 1029 } 1030 1031 bool GenCollectedHeap::is_in_young(oop p) { 1032 bool result = ((HeapWord*)p) < _old_gen->reserved().start(); 1033 assert(result == _young_gen->is_in_reserved(p), 1034 "incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)); 1035 return result; 1036 } 1037 1038 // Returns "TRUE" iff "p" points into the committed areas of the heap. 1039 bool GenCollectedHeap::is_in(const void* p) const { 1040 return _young_gen->is_in(p) || _old_gen->is_in(p); 1041 } 1042 1043 #ifdef ASSERT 1044 // Don't implement this by using is_in_young(). This method is used 1045 // in some cases to check that is_in_young() is correct. 1046 bool GenCollectedHeap::is_in_partial_collection(const void* p) { 1047 assert(is_in_reserved(p) || p == NULL, 1048 "Does not work if address is non-null and outside of the heap"); 1049 return p < _young_gen->reserved().end() && p != NULL; 1050 } 1051 #endif 1052 1053 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) { 1054 NoHeaderExtendedOopClosure no_header_cl(cl); 1055 oop_iterate(&no_header_cl); 1056 } 1057 1058 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) { 1059 _young_gen->oop_iterate(cl); 1060 _old_gen->oop_iterate(cl); 1061 } 1062 1063 void GenCollectedHeap::object_iterate(ObjectClosure* cl) { 1064 _young_gen->object_iterate(cl); 1065 _old_gen->object_iterate(cl); 1066 } 1067 1068 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) { 1069 _young_gen->safe_object_iterate(cl); 1070 _old_gen->safe_object_iterate(cl); 1071 } 1072 1073 Space* GenCollectedHeap::space_containing(const void* addr) const { 1074 Space* res = _young_gen->space_containing(addr); 1075 if (res != NULL) { 1076 return res; 1077 } 1078 res = _old_gen->space_containing(addr); 1079 assert(res != NULL, "Could not find containing space"); 1080 return res; 1081 } 1082 1083 HeapWord* GenCollectedHeap::block_start(const void* addr) const { 1084 assert(is_in_reserved(addr), "block_start of address outside of heap"); 1085 if (_young_gen->is_in_reserved(addr)) { 1086 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 1087 return _young_gen->block_start(addr); 1088 } 1089 1090 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1091 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 1092 return _old_gen->block_start(addr); 1093 } 1094 1095 size_t GenCollectedHeap::block_size(const HeapWord* addr) const { 1096 assert(is_in_reserved(addr), "block_size of address outside of heap"); 1097 if (_young_gen->is_in_reserved(addr)) { 1098 assert(_young_gen->is_in(addr), "addr should be in allocated part of generation"); 1099 return _young_gen->block_size(addr); 1100 } 1101 1102 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1103 assert(_old_gen->is_in(addr), "addr should be in allocated part of generation"); 1104 return _old_gen->block_size(addr); 1105 } 1106 1107 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const { 1108 assert(is_in_reserved(addr), "block_is_obj of address outside of heap"); 1109 assert(block_start(addr) == addr, "addr must be a block start"); 1110 if (_young_gen->is_in_reserved(addr)) { 1111 return _young_gen->block_is_obj(addr); 1112 } 1113 1114 assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address"); 1115 return _old_gen->block_is_obj(addr); 1116 } 1117 1118 bool GenCollectedHeap::supports_tlab_allocation() const { 1119 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1120 return _young_gen->supports_tlab_allocation(); 1121 } 1122 1123 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const { 1124 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1125 if (_young_gen->supports_tlab_allocation()) { 1126 return _young_gen->tlab_capacity(); 1127 } 1128 return 0; 1129 } 1130 1131 size_t GenCollectedHeap::tlab_used(Thread* thr) const { 1132 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1133 if (_young_gen->supports_tlab_allocation()) { 1134 return _young_gen->tlab_used(); 1135 } 1136 return 0; 1137 } 1138 1139 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const { 1140 assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!"); 1141 if (_young_gen->supports_tlab_allocation()) { 1142 return _young_gen->unsafe_max_tlab_alloc(); 1143 } 1144 return 0; 1145 } 1146 1147 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) { 1148 bool gc_overhead_limit_was_exceeded; 1149 return mem_allocate_work(size /* size */, 1150 true /* is_tlab */, 1151 &gc_overhead_limit_was_exceeded); 1152 } 1153 1154 // Requires "*prev_ptr" to be non-NULL. Deletes and a block of minimal size 1155 // from the list headed by "*prev_ptr". 1156 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) { 1157 bool first = true; 1158 size_t min_size = 0; // "first" makes this conceptually infinite. 1159 ScratchBlock **smallest_ptr, *smallest; 1160 ScratchBlock *cur = *prev_ptr; 1161 while (cur) { 1162 assert(*prev_ptr == cur, "just checking"); 1163 if (first || cur->num_words < min_size) { 1164 smallest_ptr = prev_ptr; 1165 smallest = cur; 1166 min_size = smallest->num_words; 1167 first = false; 1168 } 1169 prev_ptr = &cur->next; 1170 cur = cur->next; 1171 } 1172 smallest = *smallest_ptr; 1173 *smallest_ptr = smallest->next; 1174 return smallest; 1175 } 1176 1177 // Sort the scratch block list headed by res into decreasing size order, 1178 // and set "res" to the result. 1179 static void sort_scratch_list(ScratchBlock*& list) { 1180 ScratchBlock* sorted = NULL; 1181 ScratchBlock* unsorted = list; 1182 while (unsorted) { 1183 ScratchBlock *smallest = removeSmallestScratch(&unsorted); 1184 smallest->next = sorted; 1185 sorted = smallest; 1186 } 1187 list = sorted; 1188 } 1189 1190 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor, 1191 size_t max_alloc_words) { 1192 ScratchBlock* res = NULL; 1193 _young_gen->contribute_scratch(res, requestor, max_alloc_words); 1194 _old_gen->contribute_scratch(res, requestor, max_alloc_words); 1195 sort_scratch_list(res); 1196 return res; 1197 } 1198 1199 void GenCollectedHeap::release_scratch() { 1200 _young_gen->reset_scratch(); 1201 _old_gen->reset_scratch(); 1202 } 1203 1204 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure { 1205 void do_generation(Generation* gen) { 1206 gen->prepare_for_verify(); 1207 } 1208 }; 1209 1210 void GenCollectedHeap::prepare_for_verify() { 1211 ensure_parsability(false); // no need to retire TLABs 1212 GenPrepareForVerifyClosure blk; 1213 generation_iterate(&blk, false); 1214 } 1215 1216 void GenCollectedHeap::generation_iterate(GenClosure* cl, 1217 bool old_to_young) { 1218 if (old_to_young) { 1219 cl->do_generation(_old_gen); 1220 cl->do_generation(_young_gen); 1221 } else { 1222 cl->do_generation(_young_gen); 1223 cl->do_generation(_old_gen); 1224 } 1225 } 1226 1227 bool GenCollectedHeap::is_maximal_no_gc() const { 1228 return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc(); 1229 } 1230 1231 void GenCollectedHeap::save_marks() { 1232 _young_gen->save_marks(); 1233 _old_gen->save_marks(); 1234 } 1235 1236 GenCollectedHeap* GenCollectedHeap::heap() { 1237 CollectedHeap* heap = Universe::heap(); 1238 assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()"); 1239 assert(heap->kind() == CollectedHeap::SerialHeap || 1240 heap->kind() == CollectedHeap::CMSHeap, "Not a GenCollectedHeap"); 1241 return (GenCollectedHeap*) heap; 1242 } 1243 1244 void GenCollectedHeap::prepare_for_compaction() { 1245 // Start by compacting into same gen. 1246 CompactPoint cp(_old_gen); 1247 _old_gen->prepare_for_compaction(&cp); 1248 _young_gen->prepare_for_compaction(&cp); 1249 } 1250 1251 void GenCollectedHeap::verify(VerifyOption option /* ignored */) { 1252 log_debug(gc, verify)("%s", _old_gen->name()); 1253 _old_gen->verify(); 1254 1255 log_debug(gc, verify)("%s", _old_gen->name()); 1256 _young_gen->verify(); 1257 1258 log_debug(gc, verify)("RemSet"); 1259 rem_set()->verify(); 1260 } 1261 1262 void GenCollectedHeap::print_on(outputStream* st) const { 1263 _young_gen->print_on(st); 1264 _old_gen->print_on(st); 1265 MetaspaceAux::print_on(st); 1266 } 1267 1268 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const { 1269 } 1270 1271 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const { 1272 } 1273 1274 void GenCollectedHeap::print_tracing_info() const { 1275 if (log_is_enabled(Debug, gc, heap, exit)) { 1276 LogStreamHandle(Debug, gc, heap, exit) lsh; 1277 _young_gen->print_summary_info_on(&lsh); 1278 _old_gen->print_summary_info_on(&lsh); 1279 } 1280 } 1281 1282 void GenCollectedHeap::print_heap_change(size_t young_prev_used, size_t old_prev_used) const { 1283 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1284 _young_gen->short_name(), young_prev_used / K, _young_gen->used() /K, _young_gen->capacity() /K); 1285 log_info(gc, heap)("%s: " SIZE_FORMAT "K->" SIZE_FORMAT "K(" SIZE_FORMAT "K)", 1286 _old_gen->short_name(), old_prev_used / K, _old_gen->used() /K, _old_gen->capacity() /K); 1287 } 1288 1289 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure { 1290 private: 1291 bool _full; 1292 public: 1293 void do_generation(Generation* gen) { 1294 gen->gc_prologue(_full); 1295 } 1296 GenGCPrologueClosure(bool full) : _full(full) {}; 1297 }; 1298 1299 void GenCollectedHeap::gc_prologue(bool full) { 1300 assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer"); 1301 1302 // Fill TLAB's and such 1303 CollectedHeap::accumulate_statistics_all_tlabs(); 1304 ensure_parsability(true); // retire TLABs 1305 1306 // Walk generations 1307 GenGCPrologueClosure blk(full); 1308 generation_iterate(&blk, false); // not old-to-young. 1309 }; 1310 1311 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure { 1312 private: 1313 bool _full; 1314 public: 1315 void do_generation(Generation* gen) { 1316 gen->gc_epilogue(_full); 1317 } 1318 GenGCEpilogueClosure(bool full) : _full(full) {}; 1319 }; 1320 1321 void GenCollectedHeap::gc_epilogue(bool full) { 1322 #if COMPILER2_OR_JVMCI 1323 assert(DerivedPointerTable::is_empty(), "derived pointer present"); 1324 size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr())); 1325 guarantee(is_client_compilation_mode_vm() || actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps"); 1326 #endif // COMPILER2_OR_JVMCI 1327 1328 resize_all_tlabs(); 1329 1330 GenGCEpilogueClosure blk(full); 1331 generation_iterate(&blk, false); // not old-to-young. 1332 1333 if (!CleanChunkPoolAsync) { 1334 Chunk::clean_chunk_pool(); 1335 } 1336 1337 MetaspaceCounters::update_performance_counters(); 1338 CompressedClassSpaceCounters::update_performance_counters(); 1339 }; 1340 1341 #ifndef PRODUCT 1342 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure { 1343 private: 1344 public: 1345 void do_generation(Generation* gen) { 1346 gen->record_spaces_top(); 1347 } 1348 }; 1349 1350 void GenCollectedHeap::record_gen_tops_before_GC() { 1351 if (ZapUnusedHeapArea) { 1352 GenGCSaveTopsBeforeGCClosure blk; 1353 generation_iterate(&blk, false); // not old-to-young. 1354 } 1355 } 1356 #endif // not PRODUCT 1357 1358 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure { 1359 public: 1360 void do_generation(Generation* gen) { 1361 gen->ensure_parsability(); 1362 } 1363 }; 1364 1365 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) { 1366 CollectedHeap::ensure_parsability(retire_tlabs); 1367 GenEnsureParsabilityClosure ep_cl; 1368 generation_iterate(&ep_cl, false); 1369 } 1370 1371 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen, 1372 oop obj, 1373 size_t obj_size) { 1374 guarantee(old_gen == _old_gen, "We only get here with an old generation"); 1375 assert(obj_size == (size_t)obj->size(), "bad obj_size passed in"); 1376 HeapWord* result = NULL; 1377 1378 result = old_gen->expand_and_allocate(obj_size, false); 1379 1380 if (result != NULL) { 1381 Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size); 1382 } 1383 return oop(result); 1384 } 1385 1386 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure { 1387 jlong _time; // in ms 1388 jlong _now; // in ms 1389 1390 public: 1391 GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { } 1392 1393 jlong time() { return _time; } 1394 1395 void do_generation(Generation* gen) { 1396 _time = MIN2(_time, gen->time_of_last_gc(_now)); 1397 } 1398 }; 1399 1400 jlong GenCollectedHeap::millis_since_last_gc() { 1401 // javaTimeNanos() is guaranteed to be monotonically non-decreasing 1402 // provided the underlying platform provides such a time source 1403 // (and it is bug free). So we still have to guard against getting 1404 // back a time later than 'now'. 1405 jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; 1406 GenTimeOfLastGCClosure tolgc_cl(now); 1407 // iterate over generations getting the oldest 1408 // time that a generation was collected 1409 generation_iterate(&tolgc_cl, false); 1410 1411 jlong retVal = now - tolgc_cl.time(); 1412 if (retVal < 0) { 1413 log_warning(gc)("millis_since_last_gc() would return : " JLONG_FORMAT 1414 ". returning zero instead.", retVal); 1415 return 0; 1416 } 1417 return retVal; 1418 }