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