1 /*
   2  * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/symbolTable.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "classfile/vmSymbols.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc_implementation/shared/collectorCounters.hpp"
  32 #include "gc_implementation/shared/gcTrace.hpp"
  33 #include "gc_implementation/shared/gcTraceTime.hpp"
  34 #include "gc_implementation/shared/vmGCOperations.hpp"
  35 #include "gc_interface/collectedHeap.inline.hpp"
  36 #include "memory/filemap.hpp"
  37 #include "memory/gcLocker.inline.hpp"
  38 #include "memory/genCollectedHeap.hpp"
  39 #include "memory/genOopClosures.inline.hpp"
  40 #include "memory/generationSpec.hpp"
  41 #include "memory/resourceArea.hpp"
  42 #include "memory/sharedHeap.hpp"
  43 #include "memory/space.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "runtime/biasedLocking.hpp"
  46 #include "runtime/fprofiler.hpp"
  47 #include "runtime/handles.hpp"
  48 #include "runtime/handles.inline.hpp"
  49 #include "runtime/java.hpp"
  50 #include "runtime/vmThread.hpp"
  51 #include "services/management.hpp"
  52 #include "services/memoryService.hpp"
  53 #include "utilities/vmError.hpp"
  54 #include "utilities/workgroup.hpp"
  55 #include "utilities/macros.hpp"
  56 #if INCLUDE_ALL_GCS
  57 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  58 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
  59 #endif // INCLUDE_ALL_GCS
  60 
  61 GenCollectedHeap* GenCollectedHeap::_gch;
  62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
  63 
  64 // The set of potentially parallel tasks in root scanning.
  65 enum GCH_strong_roots_tasks {
  66   GCH_PS_Universe_oops_do,
  67   GCH_PS_JNIHandles_oops_do,
  68   GCH_PS_ObjectSynchronizer_oops_do,
  69   GCH_PS_FlatProfiler_oops_do,
  70   GCH_PS_Management_oops_do,
  71   GCH_PS_SystemDictionary_oops_do,
  72   GCH_PS_ClassLoaderDataGraph_oops_do,
  73   GCH_PS_jvmti_oops_do,
  74   GCH_PS_CodeCache_oops_do,
  75   GCH_PS_younger_gens,
  76   // Leave this one last.
  77   GCH_PS_NumElements
  78 };
  79 
  80 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
  81   SharedHeap(),
  82   _rem_set(NULL),
  83   _gen_policy(policy),
  84   _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
  85   _full_collections_completed(0)
  86 {
  87   assert(policy != NULL, "Sanity check");
  88   if (UseConcMarkSweepGC) {
  89     _workers = new FlexibleWorkGang("GC Thread", ParallelGCThreads,
  90                             /* are_GC_task_threads */true,
  91                             /* are_ConcurrentGC_threads */false);
  92     _workers->initialize_workers();
  93   } else {
  94     // Serial GC does not use workers
  95     _workers = NULL;
  96   }
  97 }
  98 
  99 jint GenCollectedHeap::initialize() {
 100   CollectedHeap::pre_initialize();
 101 
 102   _n_gens = gen_policy()->number_of_generations();
 103   assert(_n_gens == 2, "There is no support for more than two generations");
 104 
 105   // While there are no constraints in the GC code that HeapWordSize
 106   // be any particular value, there are multiple other areas in the
 107   // system which believe this to be true (e.g. oop->object_size in some
 108   // cases incorrectly returns the size in wordSize units rather than
 109   // HeapWordSize).
 110   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
 111 
 112   // Allocate space for the heap.
 113 
 114   char* heap_address;
 115   ReservedSpace heap_rs;
 116 
 117   size_t heap_alignment = collector_policy()->heap_alignment();
 118 
 119   heap_address = allocate(heap_alignment, &heap_rs);
 120 
 121   if (!heap_rs.is_reserved()) {
 122     vm_shutdown_during_initialization(
 123       "Could not reserve enough space for object heap");
 124     return JNI_ENOMEM;
 125   }
 126 
 127   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
 128 
 129   _rem_set = collector_policy()->create_rem_set(reserved_region());
 130   set_barrier_set(rem_set()->bs());
 131 
 132   _gch = this;
 133 
 134   ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
 135   _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set());
 136   heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
 137 
 138   ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
 139   _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set());
 140   clear_incremental_collection_failed();
 141 
 142 #if INCLUDE_ALL_GCS
 143   // If we are running CMS, create the collector responsible
 144   // for collecting the CMS generations.
 145   if (collector_policy()->is_concurrent_mark_sweep_policy()) {
 146     bool success = create_cms_collector();
 147     if (!success) return JNI_ENOMEM;
 148   }
 149 #endif // INCLUDE_ALL_GCS
 150 
 151   return JNI_OK;
 152 }
 153 
 154 char* GenCollectedHeap::allocate(size_t alignment,
 155                                  ReservedSpace* heap_rs){
 156   // Now figure out the total size.
 157   const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
 158   assert(alignment % pageSize == 0, "Must be");
 159 
 160   GenerationSpec* young_spec = gen_policy()->young_gen_spec();
 161   GenerationSpec* old_spec = gen_policy()->old_gen_spec();
 162 
 163   // Check for overflow.
 164   size_t total_reserved = young_spec->max_size() + old_spec->max_size();
 165   if (total_reserved < young_spec->max_size()) {
 166     vm_exit_during_initialization("The size of the object heap + VM data exceeds "
 167                                   "the maximum representable size");
 168   }
 169   assert(total_reserved % alignment == 0,
 170          err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
 171                  SIZE_FORMAT, total_reserved, alignment));
 172 
 173   *heap_rs = Universe::reserve_heap(total_reserved, alignment);
 174   return heap_rs->base();
 175 }
 176 
 177 void GenCollectedHeap::post_initialize() {
 178   CollectedHeap::post_initialize();
 179   ref_processing_init();
 180   GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
 181   guarantee(policy->is_generation_policy(), "Illegal policy type");
 182   assert((_young_gen->kind() == Generation::DefNew) ||
 183          (_young_gen->kind() == Generation::ParNew),
 184     "Wrong youngest generation type");
 185   DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
 186 
 187   assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
 188          _old_gen->kind() == Generation::MarkSweepCompact,
 189     "Wrong generation kind");
 190 
 191   policy->initialize_size_policy(def_new_gen->eden()->capacity(),
 192                                  _old_gen->capacity(),
 193                                  def_new_gen->from()->capacity());
 194   policy->initialize_gc_policy_counters();
 195 }
 196 
 197 void GenCollectedHeap::ref_processing_init() {
 198   _young_gen->ref_processor_init();
 199   _old_gen->ref_processor_init();
 200 }
 201 
 202 size_t GenCollectedHeap::capacity() const {
 203   return _young_gen->capacity() + _old_gen->capacity();
 204 }
 205 
 206 size_t GenCollectedHeap::used() const {
 207   return _young_gen->used() + _old_gen->used();
 208 }
 209 
 210 // Save the "used_region" for generations level and lower.
 211 void GenCollectedHeap::save_used_regions(int level) {
 212   assert(level >= 0, "Illegal level parameter");
 213   assert(level < _n_gens, "Illegal level parameter");
 214   if (level == 1) {
 215     _old_gen->save_used_region();
 216   }
 217   _young_gen->save_used_region();
 218 }
 219 
 220 size_t GenCollectedHeap::max_capacity() const {
 221   return _young_gen->max_capacity() + _old_gen->max_capacity();
 222 }
 223 
 224 // Update the _full_collections_completed counter
 225 // at the end of a stop-world full GC.
 226 unsigned int GenCollectedHeap::update_full_collections_completed() {
 227   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 228   assert(_full_collections_completed <= _total_full_collections,
 229          "Can't complete more collections than were started");
 230   _full_collections_completed = _total_full_collections;
 231   ml.notify_all();
 232   return _full_collections_completed;
 233 }
 234 
 235 // Update the _full_collections_completed counter, as appropriate,
 236 // at the end of a concurrent GC cycle. Note the conditional update
 237 // below to allow this method to be called by a concurrent collector
 238 // without synchronizing in any manner with the VM thread (which
 239 // may already have initiated a STW full collection "concurrently").
 240 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
 241   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 242   assert((_full_collections_completed <= _total_full_collections) &&
 243          (count <= _total_full_collections),
 244          "Can't complete more collections than were started");
 245   if (count > _full_collections_completed) {
 246     _full_collections_completed = count;
 247     ml.notify_all();
 248   }
 249   return _full_collections_completed;
 250 }
 251 
 252 
 253 #ifndef PRODUCT
 254 // Override of memory state checking method in CollectedHeap:
 255 // Some collectors (CMS for example) can't have badHeapWordVal written
 256 // in the first two words of an object. (For instance , in the case of
 257 // CMS these words hold state used to synchronize between certain
 258 // (concurrent) GC steps and direct allocating mutators.)
 259 // The skip_header_HeapWords() method below, allows us to skip
 260 // over the requisite number of HeapWord's. Note that (for
 261 // generational collectors) this means that those many words are
 262 // skipped in each object, irrespective of the generation in which
 263 // that object lives. The resultant loss of precision seems to be
 264 // harmless and the pain of avoiding that imprecision appears somewhat
 265 // higher than we are prepared to pay for such rudimentary debugging
 266 // support.
 267 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
 268                                                          size_t size) {
 269   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 270     // We are asked to check a size in HeapWords,
 271     // but the memory is mangled in juint words.
 272     juint* start = (juint*) (addr + skip_header_HeapWords());
 273     juint* end   = (juint*) (addr + size);
 274     for (juint* slot = start; slot < end; slot += 1) {
 275       assert(*slot == badHeapWordVal,
 276              "Found non badHeapWordValue in pre-allocation check");
 277     }
 278   }
 279 }
 280 #endif
 281 
 282 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
 283                                                bool is_tlab,
 284                                                bool first_only) {
 285   HeapWord* res = NULL;
 286 
 287   if (_young_gen->should_allocate(size, is_tlab)) {
 288     res = _young_gen->allocate(size, is_tlab);
 289     if (res != NULL || first_only) {
 290       return res;
 291     }
 292   }
 293 
 294   if (_old_gen->should_allocate(size, is_tlab)) {
 295     res = _old_gen->allocate(size, is_tlab);
 296   }
 297 
 298   return res;
 299 }
 300 
 301 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
 302                                          bool* gc_overhead_limit_was_exceeded) {
 303   return collector_policy()->mem_allocate_work(size,
 304                                                false /* is_tlab */,
 305                                                gc_overhead_limit_was_exceeded);
 306 }
 307 
 308 bool GenCollectedHeap::must_clear_all_soft_refs() {
 309   return _gc_cause == GCCause::_last_ditch_collection;
 310 }
 311 
 312 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
 313   return UseConcMarkSweepGC &&
 314          ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
 315           (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
 316 }
 317 
 318 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
 319                                           bool is_tlab, bool run_verification, bool clear_soft_refs,
 320                                           bool restore_marks_for_biased_locking) {
 321   // Timer for individual generations. Last argument is false: no CR
 322   // FIXME: We should try to start the timing earlier to cover more of the GC pause
 323   // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 324   // so we can assume here that the next GC id is what we want.
 325   GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
 326   TraceCollectorStats tcs(gen->counters());
 327   TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
 328 
 329   size_t prev_used = gen->used();
 330   gen->stat_record()->invocations++;
 331   gen->stat_record()->accumulated_time.start();
 332 
 333   // Must be done anew before each collection because
 334   // a previous collection will do mangling and will
 335   // change top of some spaces.
 336   record_gen_tops_before_GC();
 337 
 338   if (PrintGC && Verbose) {
 339     gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
 340                         gen->level(),
 341                         gen->stat_record()->invocations,
 342                         size * HeapWordSize);
 343   }
 344 
 345   if (run_verification && VerifyBeforeGC) {
 346     HandleMark hm;  // Discard invalid handles created during verification
 347     Universe::verify(" VerifyBeforeGC:");
 348   }
 349   COMPILER2_PRESENT(DerivedPointerTable::clear());
 350 
 351   if (restore_marks_for_biased_locking) {
 352     // We perform this mark word preservation work lazily
 353     // because it's only at this point that we know whether we
 354     // absolutely have to do it; we want to avoid doing it for
 355     // scavenge-only collections where it's unnecessary
 356     BiasedLocking::preserve_marks();
 357   }
 358 
 359   // Do collection work
 360   {
 361     // Note on ref discovery: For what appear to be historical reasons,
 362     // GCH enables and disabled (by enqueing) refs discovery.
 363     // In the future this should be moved into the generation's
 364     // collect method so that ref discovery and enqueueing concerns
 365     // are local to a generation. The collect method could return
 366     // an appropriate indication in the case that notification on
 367     // the ref lock was needed. This will make the treatment of
 368     // weak refs more uniform (and indeed remove such concerns
 369     // from GCH). XXX
 370 
 371     HandleMark hm;  // Discard invalid handles created during gc
 372     save_marks();   // save marks for all gens
 373     // We want to discover references, but not process them yet.
 374     // This mode is disabled in process_discovered_references if the
 375     // generation does some collection work, or in
 376     // enqueue_discovered_references if the generation returns
 377     // without doing any work.
 378     ReferenceProcessor* rp = gen->ref_processor();
 379     // If the discovery of ("weak") refs in this generation is
 380     // atomic wrt other collectors in this configuration, we
 381     // are guaranteed to have empty discovered ref lists.
 382     if (rp->discovery_is_atomic()) {
 383       rp->enable_discovery();
 384       rp->setup_policy(clear_soft_refs);
 385     } else {
 386       // collect() below will enable discovery as appropriate
 387     }
 388     gen->collect(full, clear_soft_refs, size, is_tlab);
 389     if (!rp->enqueuing_is_done()) {
 390       rp->enqueue_discovered_references();
 391     } else {
 392       rp->set_enqueuing_is_done(false);
 393     }
 394     rp->verify_no_references_recorded();
 395   }
 396 
 397   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 398 
 399   gen->stat_record()->accumulated_time.stop();
 400 
 401   update_gc_stats(gen->level(), full);
 402 
 403   if (run_verification && VerifyAfterGC) {
 404     HandleMark hm;  // Discard invalid handles created during verification
 405     Universe::verify(" VerifyAfterGC:");
 406   }
 407 
 408   if (PrintGCDetails) {
 409     gclog_or_tty->print(":");
 410     gen->print_heap_change(prev_used);
 411   }
 412 }
 413 
 414 void GenCollectedHeap::do_collection(bool   full,
 415                                      bool   clear_all_soft_refs,
 416                                      size_t size,
 417                                      bool   is_tlab,
 418                                      int    max_level) {
 419   ResourceMark rm;
 420   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 421 
 422   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 423   assert(my_thread->is_VM_thread() ||
 424          my_thread->is_ConcurrentGC_thread(),
 425          "incorrect thread type capability");
 426   assert(Heap_lock->is_locked(),
 427          "the requesting thread should have the Heap_lock");
 428   guarantee(!is_gc_active(), "collection is not reentrant");
 429   assert(max_level < n_gens(), "sanity check");
 430 
 431   if (GC_locker::check_active_before_gc()) {
 432     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 433   }
 434 
 435   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 436                           collector_policy()->should_clear_all_soft_refs();
 437 
 438   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 439 
 440   const size_t metadata_prev_used = MetaspaceAux::used_bytes();
 441 
 442   print_heap_before_gc();
 443 
 444   {
 445     FlagSetting fl(_is_gc_active, true);
 446 
 447     bool complete = full && (max_level == (n_gens()-1));
 448     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 449     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 450     // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 451     // so we can assume here that the next GC id is what we want.
 452     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
 453 
 454     gc_prologue(complete);
 455     increment_total_collections(complete);
 456 
 457     size_t gch_prev_used = used();
 458     bool run_verification = total_collections() >= VerifyGCStartAt;
 459 
 460     bool prepared_for_verification = false;
 461     int max_level_collected = 0;
 462     bool old_collects_young = (max_level == 1) &&
 463                               full &&
 464                               _old_gen->full_collects_younger_generations();
 465     if (!old_collects_young &&
 466         _young_gen->should_collect(full, size, is_tlab)) {
 467       if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
 468         prepare_for_verify();
 469         prepared_for_verification = true;
 470       }
 471 
 472       assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
 473       collect_generation(_young_gen,
 474                          full,
 475                          size,
 476                          is_tlab,
 477                          run_verification && VerifyGCLevel <= 0,
 478                          do_clear_all_soft_refs,
 479                          false);
 480 
 481       if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
 482           size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
 483         // Allocation request was met by young GC.
 484         size = 0;
 485       }
 486     }
 487 
 488     bool must_restore_marks_for_biased_locking = false;
 489 
 490     if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
 491       if (!complete) {
 492         // The full_collections increment was missed above.
 493         increment_total_full_collections();
 494       }
 495 
 496       pre_full_gc_dump(NULL);    // do any pre full gc dumps
 497 
 498       if (!prepared_for_verification && run_verification &&
 499           VerifyGCLevel <= 1 && VerifyBeforeGC) {
 500         prepare_for_verify();
 501       }
 502 
 503       assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
 504       collect_generation(_old_gen,
 505                          full,
 506                          size,
 507                          is_tlab,
 508                          run_verification && VerifyGCLevel <= 1,
 509                          do_clear_all_soft_refs,
 510                          true);
 511 
 512       must_restore_marks_for_biased_locking = true;
 513       max_level_collected = 1;
 514     }
 515 
 516     // Update "complete" boolean wrt what actually transpired --
 517     // for instance, a promotion failure could have led to
 518     // a whole heap collection.
 519     complete = complete || (max_level_collected == n_gens() - 1);
 520 
 521     if (complete) { // We did a "major" collection
 522       // FIXME: See comment at pre_full_gc_dump call
 523       post_full_gc_dump(NULL);   // do any post full gc dumps
 524     }
 525 
 526     if (PrintGCDetails) {
 527       print_heap_change(gch_prev_used);
 528 
 529       // Print metaspace info for full GC with PrintGCDetails flag.
 530       if (complete) {
 531         MetaspaceAux::print_metaspace_change(metadata_prev_used);
 532       }
 533     }
 534 
 535     // Adjust generation sizes.
 536     if (max_level_collected == 1) {
 537       _old_gen->compute_new_size();
 538     }
 539     _young_gen->compute_new_size();
 540 
 541     if (complete) {
 542       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 543       ClassLoaderDataGraph::purge();
 544       MetaspaceAux::verify_metrics();
 545       // Resize the metaspace capacity after full collections
 546       MetaspaceGC::compute_new_size();
 547       update_full_collections_completed();
 548     }
 549 
 550     // Track memory usage and detect low memory after GC finishes
 551     MemoryService::track_memory_usage();
 552 
 553     gc_epilogue(complete);
 554 
 555     if (must_restore_marks_for_biased_locking) {
 556       BiasedLocking::restore_marks();
 557     }
 558   }
 559 
 560   print_heap_after_gc();
 561 
 562 #ifdef TRACESPINNING
 563   ParallelTaskTerminator::print_termination_counts();
 564 #endif
 565 }
 566 
 567 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 568   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 569 }
 570 
 571 void GenCollectedHeap::set_par_threads(uint t) {
 572   assert(t == 0 || !UseSerialGC, "Cannot have parallel threads");
 573   CollectedHeap::set_par_threads(t);
 574   set_n_termination(t);
 575 }
 576 
 577 void GenCollectedHeap::set_n_termination(uint t) {
 578   _process_strong_tasks->set_n_threads(t);
 579 }
 580 
 581 #ifdef ASSERT
 582 class AssertNonScavengableClosure: public OopClosure {
 583 public:
 584   virtual void do_oop(oop* p) {
 585     assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
 586       "Referent should not be scavengable.");  }
 587   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 588 };
 589 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 590 #endif
 591 
 592 void GenCollectedHeap::process_roots(bool activate_scope,
 593                                      ScanningOption so,
 594                                      OopClosure* strong_roots,
 595                                      OopClosure* weak_roots,
 596                                      CLDClosure* strong_cld_closure,
 597                                      CLDClosure* weak_cld_closure,
 598                                      CodeBlobClosure* code_roots) {
 599   StrongRootsScope srs(this, activate_scope);
 600 
 601   // General roots.
 602   assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
 603   assert(code_roots != NULL, "code root closure should always be set");
 604   // _n_termination for _process_strong_tasks should be set up stream
 605   // in a method not running in a GC worker.  Otherwise the GC worker
 606   // could be trying to change the termination condition while the task
 607   // is executing in another GC worker.
 608 
 609   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
 610     ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
 611   }
 612 
 613   // Some CLDs contained in the thread frames should be considered strong.
 614   // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
 615   CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
 616   // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
 617   CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
 618 
 619   bool is_par = n_par_threads() > 0;
 620   Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
 621 
 622   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
 623     Universe::oops_do(strong_roots);
 624   }
 625   // Global (strong) JNI handles
 626   if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
 627     JNIHandles::oops_do(strong_roots);
 628   }
 629 
 630   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
 631     ObjectSynchronizer::oops_do(strong_roots);
 632   }
 633   if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
 634     FlatProfiler::oops_do(strong_roots);
 635   }
 636   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
 637     Management::oops_do(strong_roots);
 638   }
 639   if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
 640     JvmtiExport::oops_do(strong_roots);
 641   }
 642 
 643   if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
 644     SystemDictionary::roots_oops_do(strong_roots, weak_roots);
 645   }
 646 
 647   // All threads execute the following. A specific chunk of buckets
 648   // from the StringTable are the individual tasks.
 649   if (weak_roots != NULL) {
 650     if (CollectedHeap::use_parallel_gc_threads()) {
 651       StringTable::possibly_parallel_oops_do(weak_roots);
 652     } else {
 653       StringTable::oops_do(weak_roots);
 654     }
 655   }
 656 
 657   if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
 658     if (so & SO_ScavengeCodeCache) {
 659       assert(code_roots != NULL, "must supply closure for code cache");
 660 
 661       // We only visit parts of the CodeCache when scavenging.
 662       CodeCache::scavenge_root_nmethods_do(code_roots);
 663     }
 664     if (so & SO_AllCodeCache) {
 665       assert(code_roots != NULL, "must supply closure for code cache");
 666 
 667       // CMSCollector uses this to do intermediate-strength collections.
 668       // We scan the entire code cache, since CodeCache::do_unloading is not called.
 669       CodeCache::blobs_do(code_roots);
 670     }
 671     // Verify that the code cache contents are not subject to
 672     // movement by a scavenging collection.
 673     DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
 674     DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
 675   }
 676 
 677 }
 678 
 679 void GenCollectedHeap::gen_process_roots(int level,
 680                                          bool younger_gens_as_roots,
 681                                          bool activate_scope,
 682                                          ScanningOption so,
 683                                          bool only_strong_roots,
 684                                          OopsInGenClosure* not_older_gens,
 685                                          OopsInGenClosure* older_gens,
 686                                          CLDClosure* cld_closure) {
 687   const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
 688 
 689   bool is_moving_collection = false;
 690   if (level == 0 || is_adjust_phase) {
 691     // young collections are always moving
 692     is_moving_collection = true;
 693   }
 694 
 695   MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
 696   OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
 697   CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
 698 
 699   process_roots(activate_scope, so,
 700                 not_older_gens, weak_roots,
 701                 cld_closure, weak_cld_closure,
 702                 &mark_code_closure);
 703 
 704   if (younger_gens_as_roots) {
 705     if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 706       if (level == 1) {
 707         not_older_gens->set_generation(_young_gen);
 708         _young_gen->oop_iterate(not_older_gens);
 709       }
 710       not_older_gens->reset_generation();
 711     }
 712   }
 713   // When collection is parallel, all threads get to cooperate to do
 714   // older-gen scanning.
 715   if (level == 0) {
 716     older_gens->set_generation(_old_gen);
 717     rem_set()->younger_refs_iterate(_old_gen, older_gens);
 718     older_gens->reset_generation();
 719   }
 720 
 721   _process_strong_tasks->all_tasks_completed();
 722 }
 723 
 724 
 725 class AlwaysTrueClosure: public BoolObjectClosure {
 726 public:
 727   bool do_object_b(oop p) { return true; }
 728 };
 729 static AlwaysTrueClosure always_true;
 730 
 731 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
 732   JNIHandles::weak_oops_do(&always_true, root_closure);
 733   _young_gen->ref_processor()->weak_oops_do(root_closure);
 734   _old_gen->ref_processor()->weak_oops_do(root_closure);
 735 }
 736 
 737 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 738 void GenCollectedHeap::                                                 \
 739 oop_since_save_marks_iterate(int level,                                 \
 740                              OopClosureType* cur,                       \
 741                              OopClosureType* older) {                   \
 742   if (level == 0) {                                                     \
 743     _young_gen->oop_since_save_marks_iterate##nv_suffix(cur);           \
 744     _old_gen->oop_since_save_marks_iterate##nv_suffix(older);           \
 745   } else {                                                              \
 746     _old_gen->oop_since_save_marks_iterate##nv_suffix(cur);             \
 747   }                                                                     \
 748 }
 749 
 750 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 751 
 752 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 753 
 754 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
 755   if (level == 0 && !_young_gen->no_allocs_since_save_marks()) {
 756     return false;
 757   }
 758   return _old_gen->no_allocs_since_save_marks();
 759 }
 760 
 761 bool GenCollectedHeap::supports_inline_contig_alloc() const {
 762   return _young_gen->supports_inline_contig_alloc();
 763 }
 764 
 765 HeapWord** GenCollectedHeap::top_addr() const {
 766   return _young_gen->top_addr();
 767 }
 768 
 769 HeapWord** GenCollectedHeap::end_addr() const {
 770   return _young_gen->end_addr();
 771 }
 772 
 773 // public collection interfaces
 774 
 775 void GenCollectedHeap::collect(GCCause::Cause cause) {
 776   if (should_do_concurrent_full_gc(cause)) {
 777 #if INCLUDE_ALL_GCS
 778     // mostly concurrent full collection
 779     collect_mostly_concurrent(cause);
 780 #else  // INCLUDE_ALL_GCS
 781     ShouldNotReachHere();
 782 #endif // INCLUDE_ALL_GCS
 783   } else if (cause == GCCause::_wb_young_gc) {
 784     // minor collection for WhiteBox API
 785     collect(cause, 0);
 786   } else {
 787 #ifdef ASSERT
 788   if (cause == GCCause::_scavenge_alot) {
 789     // minor collection only
 790     collect(cause, 0);
 791   } else {
 792     // Stop-the-world full collection
 793     collect(cause, n_gens() - 1);
 794   }
 795 #else
 796     // Stop-the-world full collection
 797     collect(cause, n_gens() - 1);
 798 #endif
 799   }
 800 }
 801 
 802 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
 803   // The caller doesn't have the Heap_lock
 804   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 805   MutexLocker ml(Heap_lock);
 806   collect_locked(cause, max_level);
 807 }
 808 
 809 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
 810   // The caller has the Heap_lock
 811   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
 812   collect_locked(cause, n_gens() - 1);
 813 }
 814 
 815 // this is the private collection interface
 816 // The Heap_lock is expected to be held on entry.
 817 
 818 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
 819   // Read the GC count while holding the Heap_lock
 820   unsigned int gc_count_before      = total_collections();
 821   unsigned int full_gc_count_before = total_full_collections();
 822   {
 823     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
 824     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
 825                          cause, max_level);
 826     VMThread::execute(&op);
 827   }
 828 }
 829 
 830 #if INCLUDE_ALL_GCS
 831 bool GenCollectedHeap::create_cms_collector() {
 832 
 833   assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
 834          "Unexpected generation kinds");
 835   // Skip two header words in the block content verification
 836   NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
 837   CMSCollector* collector = new CMSCollector(
 838     (ConcurrentMarkSweepGeneration*)_old_gen,
 839     _rem_set->as_CardTableRS(),
 840     (ConcurrentMarkSweepPolicy*) collector_policy());
 841 
 842   if (collector == NULL || !collector->completed_initialization()) {
 843     if (collector) {
 844       delete collector;  // Be nice in embedded situation
 845     }
 846     vm_shutdown_during_initialization("Could not create CMS collector");
 847     return false;
 848   }
 849   return true;  // success
 850 }
 851 
 852 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
 853   assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
 854 
 855   MutexLocker ml(Heap_lock);
 856   // Read the GC counts while holding the Heap_lock
 857   unsigned int full_gc_count_before = total_full_collections();
 858   unsigned int gc_count_before      = total_collections();
 859   {
 860     MutexUnlocker mu(Heap_lock);
 861     VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
 862     VMThread::execute(&op);
 863   }
 864 }
 865 #endif // INCLUDE_ALL_GCS
 866 
 867 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
 868    do_full_collection(clear_all_soft_refs, _n_gens - 1);
 869 }
 870 
 871 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 872                                           int max_level) {
 873   int local_max_level;
 874   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 875       gc_cause() == GCCause::_gc_locker) {
 876     local_max_level = 0;
 877   } else {
 878     local_max_level = max_level;
 879   }
 880 
 881   do_collection(true                 /* full */,
 882                 clear_all_soft_refs  /* clear_all_soft_refs */,
 883                 0                    /* size */,
 884                 false                /* is_tlab */,
 885                 local_max_level      /* max_level */);
 886   // Hack XXX FIX ME !!!
 887   // A scavenge may not have been attempted, or may have
 888   // been attempted and failed, because the old gen was too full
 889   if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
 890       incremental_collection_will_fail(false /* don't consult_young */)) {
 891     if (PrintGCDetails) {
 892       gclog_or_tty->print_cr("GC locker: Trying a full collection "
 893                              "because scavenge failed");
 894     }
 895     // This time allow the old gen to be collected as well
 896     do_collection(true                 /* full */,
 897                   clear_all_soft_refs  /* clear_all_soft_refs */,
 898                   0                    /* size */,
 899                   false                /* is_tlab */,
 900                   n_gens() - 1         /* max_level */);
 901   }
 902 }
 903 
 904 bool GenCollectedHeap::is_in_young(oop p) {
 905   bool result = ((HeapWord*)p) < _old_gen->reserved().start();
 906   assert(result == _young_gen->is_in_reserved(p),
 907          err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
 908   return result;
 909 }
 910 
 911 // Returns "TRUE" iff "p" points into the committed areas of the heap.
 912 bool GenCollectedHeap::is_in(const void* p) const {
 913   #ifndef ASSERT
 914   guarantee(VerifyBeforeGC      ||
 915             VerifyDuringGC      ||
 916             VerifyBeforeExit    ||
 917             VerifyDuringStartup ||
 918             PrintAssembly       ||
 919             tty->count() != 0   ||   // already printing
 920             VerifyAfterGC       ||
 921     VMError::fatal_error_in_progress(), "too expensive");
 922 
 923   #endif
 924   return _young_gen->is_in(p) || _old_gen->is_in(p);
 925 }
 926 
 927 #ifdef ASSERT
 928 // Don't implement this by using is_in_young().  This method is used
 929 // in some cases to check that is_in_young() is correct.
 930 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
 931   assert(is_in_reserved(p) || p == NULL,
 932     "Does not work if address is non-null and outside of the heap");
 933   return p < _young_gen->reserved().end() && p != NULL;
 934 }
 935 #endif
 936 
 937 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
 938   NoHeaderExtendedOopClosure no_header_cl(cl);
 939   oop_iterate(&no_header_cl);
 940 }
 941 
 942 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
 943   _young_gen->oop_iterate(cl);
 944   _old_gen->oop_iterate(cl);
 945 }
 946 
 947 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
 948   _young_gen->object_iterate(cl);
 949   _old_gen->object_iterate(cl);
 950 }
 951 
 952 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
 953   _young_gen->safe_object_iterate(cl);
 954   _old_gen->safe_object_iterate(cl);
 955 }
 956 
 957 Space* GenCollectedHeap::space_containing(const void* addr) const {
 958   Space* res = _young_gen->space_containing(addr);
 959   if (res != NULL) {
 960     return res;
 961   }
 962   res = _old_gen->space_containing(addr);
 963   assert(res != NULL, "Could not find containing space");
 964   return res;
 965 }
 966 
 967 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
 968   assert(is_in_reserved(addr), "block_start of address outside of heap");
 969   if (_young_gen->is_in_reserved(addr)) {
 970     assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
 971     return _young_gen->block_start(addr);
 972   }
 973 
 974   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
 975   assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
 976   return _old_gen->block_start(addr);
 977 }
 978 
 979 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
 980   assert(is_in_reserved(addr), "block_size of address outside of heap");
 981   if (_young_gen->is_in_reserved(addr)) {
 982     assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
 983     return _young_gen->block_size(addr);
 984   }
 985 
 986   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
 987   assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
 988   return _old_gen->block_size(addr);
 989 }
 990 
 991 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
 992   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
 993   assert(block_start(addr) == addr, "addr must be a block start");
 994   if (_young_gen->is_in_reserved(addr)) {
 995     return _young_gen->block_is_obj(addr);
 996   }
 997 
 998   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
 999   return _old_gen->block_is_obj(addr);
1000 }
1001 
1002 bool GenCollectedHeap::supports_tlab_allocation() const {
1003   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1004   return _young_gen->supports_tlab_allocation();
1005 }
1006 
1007 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
1008   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1009   if (_young_gen->supports_tlab_allocation()) {
1010     return _young_gen->tlab_capacity();
1011   }
1012   return 0;
1013 }
1014 
1015 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1016   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1017   if (_young_gen->supports_tlab_allocation()) {
1018     return _young_gen->tlab_used();
1019   }
1020   return 0;
1021 }
1022 
1023 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1024   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1025   if (_young_gen->supports_tlab_allocation()) {
1026     return _young_gen->unsafe_max_tlab_alloc();
1027   }
1028   return 0;
1029 }
1030 
1031 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1032   bool gc_overhead_limit_was_exceeded;
1033   return collector_policy()->mem_allocate_work(size /* size */,
1034                                                true /* is_tlab */,
1035                                                &gc_overhead_limit_was_exceeded);
1036 }
1037 
1038 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
1039 // from the list headed by "*prev_ptr".
1040 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1041   bool first = true;
1042   size_t min_size = 0;   // "first" makes this conceptually infinite.
1043   ScratchBlock **smallest_ptr, *smallest;
1044   ScratchBlock  *cur = *prev_ptr;
1045   while (cur) {
1046     assert(*prev_ptr == cur, "just checking");
1047     if (first || cur->num_words < min_size) {
1048       smallest_ptr = prev_ptr;
1049       smallest     = cur;
1050       min_size     = smallest->num_words;
1051       first        = false;
1052     }
1053     prev_ptr = &cur->next;
1054     cur     =  cur->next;
1055   }
1056   smallest      = *smallest_ptr;
1057   *smallest_ptr = smallest->next;
1058   return smallest;
1059 }
1060 
1061 // Sort the scratch block list headed by res into decreasing size order,
1062 // and set "res" to the result.
1063 static void sort_scratch_list(ScratchBlock*& list) {
1064   ScratchBlock* sorted = NULL;
1065   ScratchBlock* unsorted = list;
1066   while (unsorted) {
1067     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1068     smallest->next  = sorted;
1069     sorted          = smallest;
1070   }
1071   list = sorted;
1072 }
1073 
1074 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1075                                                size_t max_alloc_words) {
1076   ScratchBlock* res = NULL;
1077   _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1078   _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1079   sort_scratch_list(res);
1080   return res;
1081 }
1082 
1083 void GenCollectedHeap::release_scratch() {
1084   _young_gen->reset_scratch();
1085   _old_gen->reset_scratch();
1086 }
1087 
1088 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1089   void do_generation(Generation* gen) {
1090     gen->prepare_for_verify();
1091   }
1092 };
1093 
1094 void GenCollectedHeap::prepare_for_verify() {
1095   ensure_parsability(false);        // no need to retire TLABs
1096   GenPrepareForVerifyClosure blk;
1097   generation_iterate(&blk, false);
1098 }
1099 
1100 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1101                                           bool old_to_young) {
1102   if (old_to_young) {
1103     cl->do_generation(_old_gen);
1104     cl->do_generation(_young_gen);
1105   } else {
1106     cl->do_generation(_young_gen);
1107     cl->do_generation(_old_gen);
1108   }
1109 }
1110 
1111 bool GenCollectedHeap::is_maximal_no_gc() const {
1112   return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1113 }
1114 
1115 void GenCollectedHeap::save_marks() {
1116   _young_gen->save_marks();
1117   _old_gen->save_marks();
1118 }
1119 
1120 GenCollectedHeap* GenCollectedHeap::heap() {
1121   assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1122   assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1123   return _gch;
1124 }
1125 
1126 
1127 void GenCollectedHeap::prepare_for_compaction() {
1128   guarantee(_n_gens = 2, "Wrong number of generations");
1129   // Start by compacting into same gen.
1130   CompactPoint cp(_old_gen);
1131   _old_gen->prepare_for_compaction(&cp);
1132   _young_gen->prepare_for_compaction(&cp);
1133 }
1134 
1135 GCStats* GenCollectedHeap::gc_stats(int level) const {
1136   if (level == 0) {
1137     return _young_gen->gc_stats();
1138   } else {
1139     return _old_gen->gc_stats();
1140   }
1141 }
1142 
1143 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1144   if (!silent) {
1145     gclog_or_tty->print("%s", _old_gen->name());
1146     gclog_or_tty->print(" ");
1147   }
1148   _old_gen->verify();
1149 
1150   if (!silent) {
1151     gclog_or_tty->print("%s", _young_gen->name());
1152     gclog_or_tty->print(" ");
1153   }
1154   _young_gen->verify();
1155 
1156   if (!silent) {
1157     gclog_or_tty->print("remset ");
1158   }
1159   rem_set()->verify();
1160 }
1161 
1162 void GenCollectedHeap::print_on(outputStream* st) const {
1163   _young_gen->print_on(st);
1164   _old_gen->print_on(st);
1165   MetaspaceAux::print_on(st);
1166 }
1167 
1168 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1169   if (workers() != NULL) {
1170     workers()->threads_do(tc);
1171   }
1172 #if INCLUDE_ALL_GCS
1173   if (UseConcMarkSweepGC) {
1174     ConcurrentMarkSweepThread::threads_do(tc);
1175   }
1176 #endif // INCLUDE_ALL_GCS
1177 }
1178 
1179 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1180 #if INCLUDE_ALL_GCS
1181   if (UseConcMarkSweepGC) {
1182     workers()->print_worker_threads_on(st);
1183     ConcurrentMarkSweepThread::print_all_on(st);
1184   }
1185 #endif // INCLUDE_ALL_GCS
1186 }
1187 
1188 void GenCollectedHeap::print_on_error(outputStream* st) const {
1189   this->CollectedHeap::print_on_error(st);
1190 
1191 #if INCLUDE_ALL_GCS
1192   if (UseConcMarkSweepGC) {
1193     st->cr();
1194     CMSCollector::print_on_error(st);
1195   }
1196 #endif // INCLUDE_ALL_GCS
1197 }
1198 
1199 void GenCollectedHeap::print_tracing_info() const {
1200   if (TraceYoungGenTime) {
1201     _young_gen->print_summary_info();
1202   }
1203   if (TraceOldGenTime) {
1204     _old_gen->print_summary_info();
1205   }
1206 }
1207 
1208 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1209   if (PrintGCDetails && Verbose) {
1210     gclog_or_tty->print(" "  SIZE_FORMAT
1211                         "->" SIZE_FORMAT
1212                         "("  SIZE_FORMAT ")",
1213                         prev_used, used(), capacity());
1214   } else {
1215     gclog_or_tty->print(" "  SIZE_FORMAT "K"
1216                         "->" SIZE_FORMAT "K"
1217                         "("  SIZE_FORMAT "K)",
1218                         prev_used / K, used() / K, capacity() / K);
1219   }
1220 }
1221 
1222 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1223  private:
1224   bool _full;
1225  public:
1226   void do_generation(Generation* gen) {
1227     gen->gc_prologue(_full);
1228   }
1229   GenGCPrologueClosure(bool full) : _full(full) {};
1230 };
1231 
1232 void GenCollectedHeap::gc_prologue(bool full) {
1233   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1234 
1235   always_do_update_barrier = false;
1236   // Fill TLAB's and such
1237   CollectedHeap::accumulate_statistics_all_tlabs();
1238   ensure_parsability(true);   // retire TLABs
1239 
1240   // Walk generations
1241   GenGCPrologueClosure blk(full);
1242   generation_iterate(&blk, false);  // not old-to-young.
1243 };
1244 
1245 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1246  private:
1247   bool _full;
1248  public:
1249   void do_generation(Generation* gen) {
1250     gen->gc_epilogue(_full);
1251   }
1252   GenGCEpilogueClosure(bool full) : _full(full) {};
1253 };
1254 
1255 void GenCollectedHeap::gc_epilogue(bool full) {
1256 #ifdef COMPILER2
1257   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1258   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1259   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1260 #endif /* COMPILER2 */
1261 
1262   resize_all_tlabs();
1263 
1264   GenGCEpilogueClosure blk(full);
1265   generation_iterate(&blk, false);  // not old-to-young.
1266 
1267   if (!CleanChunkPoolAsync) {
1268     Chunk::clean_chunk_pool();
1269   }
1270 
1271   MetaspaceCounters::update_performance_counters();
1272   CompressedClassSpaceCounters::update_performance_counters();
1273 
1274   always_do_update_barrier = UseConcMarkSweepGC;
1275 };
1276 
1277 #ifndef PRODUCT
1278 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1279  private:
1280  public:
1281   void do_generation(Generation* gen) {
1282     gen->record_spaces_top();
1283   }
1284 };
1285 
1286 void GenCollectedHeap::record_gen_tops_before_GC() {
1287   if (ZapUnusedHeapArea) {
1288     GenGCSaveTopsBeforeGCClosure blk;
1289     generation_iterate(&blk, false);  // not old-to-young.
1290   }
1291 }
1292 #endif  // not PRODUCT
1293 
1294 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1295  public:
1296   void do_generation(Generation* gen) {
1297     gen->ensure_parsability();
1298   }
1299 };
1300 
1301 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1302   CollectedHeap::ensure_parsability(retire_tlabs);
1303   GenEnsureParsabilityClosure ep_cl;
1304   generation_iterate(&ep_cl, false);
1305 }
1306 
1307 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1308                                               oop obj,
1309                                               size_t obj_size) {
1310   guarantee(old_gen->level() == 1, "We only get here with an old generation");
1311   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1312   HeapWord* result = NULL;
1313 
1314   result = old_gen->expand_and_allocate(obj_size, false);
1315 
1316   if (result != NULL) {
1317     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1318   }
1319   return oop(result);
1320 }
1321 
1322 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1323   jlong _time;   // in ms
1324   jlong _now;    // in ms
1325 
1326  public:
1327   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1328 
1329   jlong time() { return _time; }
1330 
1331   void do_generation(Generation* gen) {
1332     _time = MIN2(_time, gen->time_of_last_gc(_now));
1333   }
1334 };
1335 
1336 jlong GenCollectedHeap::millis_since_last_gc() {
1337   // We need a monotonically non-decreasing time in ms but
1338   // os::javaTimeMillis() does not guarantee monotonicity.
1339   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1340   GenTimeOfLastGCClosure tolgc_cl(now);
1341   // iterate over generations getting the oldest
1342   // time that a generation was collected
1343   generation_iterate(&tolgc_cl, false);
1344 
1345   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1346   // provided the underlying platform provides such a time source
1347   // (and it is bug free). So we still have to guard against getting
1348   // back a time later than 'now'.
1349   jlong retVal = now - tolgc_cl.time();
1350   if (retVal < 0) {
1351     NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1352     return 0;
1353   }
1354   return retVal;
1355 }