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