1 /*
   2  * Copyright (c) 2000, 2014, 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/icBuffer.hpp"
  30 #include "gc_implementation/shared/collectorCounters.hpp"
  31 #include "gc_implementation/shared/gcTrace.hpp"
  32 #include "gc_implementation/shared/gcTraceTime.hpp"
  33 #include "gc_implementation/shared/vmGCOperations.hpp"
  34 #include "gc_interface/collectedHeap.inline.hpp"
  35 #include "memory/filemap.hpp"
  36 #include "memory/gcLocker.inline.hpp"
  37 #include "memory/genCollectedHeap.hpp"
  38 #include "memory/genOopClosures.inline.hpp"
  39 #include "memory/generation.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 "oops/oop.inline2.hpp"
  46 #include "runtime/biasedLocking.hpp"
  47 #include "runtime/fprofiler.hpp"
  48 #include "runtime/handles.hpp"
  49 #include "runtime/handles.inline.hpp"
  50 #include "runtime/java.hpp"
  51 #include "runtime/vmThread.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   // We probably want to parallelize both of these internally, but for now...
  67   GCH_PS_younger_gens,
  68   // Leave this one last.
  69   GCH_PS_NumElements
  70 };
  71 
  72 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
  73   SharedHeap(policy),
  74   _gen_policy(policy),
  75   _gen_process_roots_tasks(new SubTasksDone(GCH_PS_NumElements)),
  76   _full_collections_completed(0)
  77 {
  78   if (_gen_process_roots_tasks == NULL ||
  79       !_gen_process_roots_tasks->valid()) {
  80     vm_exit_during_initialization("Failed necessary allocation.");
  81   }
  82   assert(policy != NULL, "Sanity check");
  83 }
  84 
  85 jint GenCollectedHeap::initialize() {
  86   CollectedHeap::pre_initialize();
  87 
  88   int i;
  89   _n_gens = gen_policy()->number_of_generations();
  90 
  91   // While there are no constraints in the GC code that HeapWordSize
  92   // be any particular value, there are multiple other areas in the
  93   // system which believe this to be true (e.g. oop->object_size in some
  94   // cases incorrectly returns the size in wordSize units rather than
  95   // HeapWordSize).
  96   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
  97 
  98   // The heap must be at least as aligned as generations.
  99   size_t gen_alignment = Generation::GenGrain;
 100 
 101   _gen_specs = gen_policy()->generations();
 102 
 103   // Make sure the sizes are all aligned.
 104   for (i = 0; i < _n_gens; i++) {
 105     _gen_specs[i]->align(gen_alignment);
 106   }
 107 
 108   // Allocate space for the heap.
 109 
 110   char* heap_address;
 111   size_t total_reserved = 0;
 112   int n_covered_regions = 0;
 113   ReservedSpace heap_rs;
 114 
 115   size_t heap_alignment = collector_policy()->heap_alignment();
 116 
 117   heap_address = allocate(heap_alignment, &total_reserved,
 118                           &n_covered_regions, &heap_rs);
 119 
 120   if (!heap_rs.is_reserved()) {
 121     vm_shutdown_during_initialization(
 122       "Could not reserve enough space for object heap");
 123     return JNI_ENOMEM;
 124   }
 125 
 126   _reserved = MemRegion((HeapWord*)heap_rs.base(),
 127                         (HeapWord*)(heap_rs.base() + heap_rs.size()));
 128 
 129   // It is important to do this in a way such that concurrent readers can't
 130   // temporarily think somethings in the heap.  (Seen this happen in asserts.)
 131   _reserved.set_word_size(0);
 132   _reserved.set_start((HeapWord*)heap_rs.base());
 133   size_t actual_heap_size = heap_rs.size();
 134   _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
 135 
 136   _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
 137   set_barrier_set(rem_set()->bs());
 138 
 139   _gch = this;
 140 
 141   for (i = 0; i < _n_gens; i++) {
 142     ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), false, false);
 143     _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
 144     heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
 145   }
 146   clear_incremental_collection_failed();
 147 
 148 #if INCLUDE_ALL_GCS
 149   // If we are running CMS, create the collector responsible
 150   // for collecting the CMS generations.
 151   if (collector_policy()->is_concurrent_mark_sweep_policy()) {
 152     bool success = create_cms_collector();
 153     if (!success) return JNI_ENOMEM;
 154   }
 155 #endif // INCLUDE_ALL_GCS
 156 
 157   return JNI_OK;
 158 }
 159 
 160 
 161 char* GenCollectedHeap::allocate(size_t alignment,
 162                                  size_t* _total_reserved,
 163                                  int* _n_covered_regions,
 164                                  ReservedSpace* heap_rs){
 165   const char overflow_msg[] = "The size of the object heap + VM data exceeds "
 166     "the maximum representable size";
 167 
 168   // Now figure out the total size.
 169   size_t total_reserved = 0;
 170   int n_covered_regions = 0;
 171   const size_t pageSize = UseLargePages ?
 172       os::large_page_size() : os::vm_page_size();
 173 
 174   assert(alignment % pageSize == 0, "Must be");
 175 
 176   for (int i = 0; i < _n_gens; i++) {
 177     total_reserved += _gen_specs[i]->max_size();
 178     if (total_reserved < _gen_specs[i]->max_size()) {
 179       vm_exit_during_initialization(overflow_msg);
 180     }
 181     n_covered_regions += _gen_specs[i]->n_covered_regions();
 182   }
 183   assert(total_reserved % alignment == 0,
 184          err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
 185                  SIZE_FORMAT, total_reserved, alignment));
 186 
 187   // Needed until the cardtable is fixed to have the right number
 188   // of covered regions.
 189   n_covered_regions += 2;
 190 
 191   *_total_reserved = total_reserved;
 192   *_n_covered_regions = n_covered_regions;
 193 
 194   *heap_rs = Universe::reserve_heap(total_reserved, alignment);
 195   return heap_rs->base();
 196 }
 197 
 198 
 199 void GenCollectedHeap::post_initialize() {
 200   SharedHeap::post_initialize();
 201   TwoGenerationCollectorPolicy *policy =
 202     (TwoGenerationCollectorPolicy *)collector_policy();
 203   guarantee(policy->is_two_generation_policy(), "Illegal policy type");
 204   DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
 205   assert(def_new_gen->kind() == Generation::DefNew ||
 206          def_new_gen->kind() == Generation::ParNew ||
 207          def_new_gen->kind() == Generation::ASParNew,
 208          "Wrong generation kind");
 209 
 210   Generation* old_gen = get_gen(1);
 211   assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
 212          old_gen->kind() == Generation::ASConcurrentMarkSweep ||
 213          old_gen->kind() == Generation::MarkSweepCompact,
 214     "Wrong generation kind");
 215 
 216   policy->initialize_size_policy(def_new_gen->eden()->capacity(),
 217                                  old_gen->capacity(),
 218                                  def_new_gen->from()->capacity());
 219   policy->initialize_gc_policy_counters();
 220 }
 221 
 222 void GenCollectedHeap::ref_processing_init() {
 223   SharedHeap::ref_processing_init();
 224   for (int i = 0; i < _n_gens; i++) {
 225     _gens[i]->ref_processor_init();
 226   }
 227 }
 228 
 229 size_t GenCollectedHeap::capacity() const {
 230   size_t res = 0;
 231   for (int i = 0; i < _n_gens; i++) {
 232     res += _gens[i]->capacity();
 233   }
 234   return res;
 235 }
 236 
 237 size_t GenCollectedHeap::used() const {
 238   size_t res = 0;
 239   for (int i = 0; i < _n_gens; i++) {
 240     res += _gens[i]->used();
 241   }
 242   return res;
 243 }
 244 
 245 // Save the "used_region" for generations level and lower.
 246 void GenCollectedHeap::save_used_regions(int level) {
 247   assert(level < _n_gens, "Illegal level parameter");
 248   for (int i = level; i >= 0; i--) {
 249     _gens[i]->save_used_region();
 250   }
 251 }
 252 
 253 size_t GenCollectedHeap::max_capacity() const {
 254   size_t res = 0;
 255   for (int i = 0; i < _n_gens; i++) {
 256     res += _gens[i]->max_capacity();
 257   }
 258   return res;
 259 }
 260 
 261 // Update the _full_collections_completed counter
 262 // at the end of a stop-world full GC.
 263 unsigned int GenCollectedHeap::update_full_collections_completed() {
 264   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 265   assert(_full_collections_completed <= _total_full_collections,
 266          "Can't complete more collections than were started");
 267   _full_collections_completed = _total_full_collections;
 268   ml.notify_all();
 269   return _full_collections_completed;
 270 }
 271 
 272 // Update the _full_collections_completed counter, as appropriate,
 273 // at the end of a concurrent GC cycle. Note the conditional update
 274 // below to allow this method to be called by a concurrent collector
 275 // without synchronizing in any manner with the VM thread (which
 276 // may already have initiated a STW full collection "concurrently").
 277 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
 278   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 279   assert((_full_collections_completed <= _total_full_collections) &&
 280          (count <= _total_full_collections),
 281          "Can't complete more collections than were started");
 282   if (count > _full_collections_completed) {
 283     _full_collections_completed = count;
 284     ml.notify_all();
 285   }
 286   return _full_collections_completed;
 287 }
 288 
 289 
 290 #ifndef PRODUCT
 291 // Override of memory state checking method in CollectedHeap:
 292 // Some collectors (CMS for example) can't have badHeapWordVal written
 293 // in the first two words of an object. (For instance , in the case of
 294 // CMS these words hold state used to synchronize between certain
 295 // (concurrent) GC steps and direct allocating mutators.)
 296 // The skip_header_HeapWords() method below, allows us to skip
 297 // over the requisite number of HeapWord's. Note that (for
 298 // generational collectors) this means that those many words are
 299 // skipped in each object, irrespective of the generation in which
 300 // that object lives. The resultant loss of precision seems to be
 301 // harmless and the pain of avoiding that imprecision appears somewhat
 302 // higher than we are prepared to pay for such rudimentary debugging
 303 // support.
 304 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
 305                                                          size_t size) {
 306   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 307     // We are asked to check a size in HeapWords,
 308     // but the memory is mangled in juint words.
 309     juint* start = (juint*) (addr + skip_header_HeapWords());
 310     juint* end   = (juint*) (addr + size);
 311     for (juint* slot = start; slot < end; slot += 1) {
 312       assert(*slot == badHeapWordVal,
 313              "Found non badHeapWordValue in pre-allocation check");
 314     }
 315   }
 316 }
 317 #endif
 318 
 319 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
 320                                                bool is_tlab,
 321                                                bool first_only) {
 322   HeapWord* res;
 323   for (int i = 0; i < _n_gens; i++) {
 324     if (_gens[i]->should_allocate(size, is_tlab)) {
 325       res = _gens[i]->allocate(size, is_tlab);
 326       if (res != NULL) return res;
 327       else if (first_only) break;
 328     }
 329   }
 330   // Otherwise...
 331   return NULL;
 332 }
 333 
 334 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
 335                                          bool* gc_overhead_limit_was_exceeded) {
 336   return collector_policy()->mem_allocate_work(size,
 337                                                false /* is_tlab */,
 338                                                gc_overhead_limit_was_exceeded);
 339 }
 340 
 341 bool GenCollectedHeap::must_clear_all_soft_refs() {
 342   return _gc_cause == GCCause::_last_ditch_collection;
 343 }
 344 
 345 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
 346   return UseConcMarkSweepGC &&
 347          ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
 348           (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
 349 }
 350 
 351 void GenCollectedHeap::do_collection(bool  full,
 352                                      bool   clear_all_soft_refs,
 353                                      size_t size,
 354                                      bool   is_tlab,
 355                                      int    max_level) {
 356   bool prepared_for_verification = false;
 357   ResourceMark rm;
 358   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 359 
 360   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 361   assert(my_thread->is_VM_thread() ||
 362          my_thread->is_ConcurrentGC_thread(),
 363          "incorrect thread type capability");
 364   assert(Heap_lock->is_locked(),
 365          "the requesting thread should have the Heap_lock");
 366   guarantee(!is_gc_active(), "collection is not reentrant");
 367   assert(max_level < n_gens(), "sanity check");
 368 
 369   if (GC_locker::check_active_before_gc()) {
 370     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 371   }
 372 
 373   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 374                           collector_policy()->should_clear_all_soft_refs();
 375 
 376   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 377 
 378   const size_t metadata_prev_used = MetaspaceAux::used_bytes();
 379 
 380   print_heap_before_gc();
 381 
 382   {
 383     FlagSetting fl(_is_gc_active, true);
 384 
 385     bool complete = full && (max_level == (n_gens()-1));
 386     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 387     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 388     // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 389     // so we can assume here that the next GC id is what we want.
 390     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
 391 
 392     gc_prologue(complete);
 393     increment_total_collections(complete);
 394 
 395     size_t gch_prev_used = used();
 396 
 397     int starting_level = 0;
 398     if (full) {
 399       // Search for the oldest generation which will collect all younger
 400       // generations, and start collection loop there.
 401       for (int i = max_level; i >= 0; i--) {
 402         if (_gens[i]->full_collects_younger_generations()) {
 403           starting_level = i;
 404           break;
 405         }
 406       }
 407     }
 408 
 409     bool must_restore_marks_for_biased_locking = false;
 410 
 411     int max_level_collected = starting_level;
 412     for (int i = starting_level; i <= max_level; i++) {
 413       if (_gens[i]->should_collect(full, size, is_tlab)) {
 414         if (i == n_gens() - 1) {  // a major collection is to happen
 415           if (!complete) {
 416             // The full_collections increment was missed above.
 417             increment_total_full_collections();
 418           }
 419           pre_full_gc_dump(NULL);    // do any pre full gc dumps
 420         }
 421         // Timer for individual generations. Last argument is false: no CR
 422         // FIXME: We should try to start the timing earlier to cover more of the GC pause
 423         // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 424         // so we can assume here that the next GC id is what we want.
 425         GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
 426         TraceCollectorStats tcs(_gens[i]->counters());
 427         TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
 428 
 429         size_t prev_used = _gens[i]->used();
 430         _gens[i]->stat_record()->invocations++;
 431         _gens[i]->stat_record()->accumulated_time.start();
 432 
 433         // Must be done anew before each collection because
 434         // a previous collection will do mangling and will
 435         // change top of some spaces.
 436         record_gen_tops_before_GC();
 437 
 438         if (PrintGC && Verbose) {
 439           gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
 440                      i,
 441                      _gens[i]->stat_record()->invocations,
 442                      size*HeapWordSize);
 443         }
 444 
 445         if (VerifyBeforeGC && i >= VerifyGCLevel &&
 446             total_collections() >= VerifyGCStartAt) {
 447           HandleMark hm;  // Discard invalid handles created during verification
 448           if (!prepared_for_verification) {
 449             prepare_for_verify();
 450             prepared_for_verification = true;
 451           }
 452           Universe::verify(" VerifyBeforeGC:");
 453         }
 454         COMPILER2_PRESENT(DerivedPointerTable::clear());
 455 
 456         if (!must_restore_marks_for_biased_locking &&
 457             _gens[i]->performs_in_place_marking()) {
 458           // We perform this mark word preservation work lazily
 459           // because it's only at this point that we know whether we
 460           // absolutely have to do it; we want to avoid doing it for
 461           // scavenge-only collections where it's unnecessary
 462           must_restore_marks_for_biased_locking = true;
 463           BiasedLocking::preserve_marks();
 464         }
 465 
 466         // Do collection work
 467         {
 468           // Note on ref discovery: For what appear to be historical reasons,
 469           // GCH enables and disabled (by enqueing) refs discovery.
 470           // In the future this should be moved into the generation's
 471           // collect method so that ref discovery and enqueueing concerns
 472           // are local to a generation. The collect method could return
 473           // an appropriate indication in the case that notification on
 474           // the ref lock was needed. This will make the treatment of
 475           // weak refs more uniform (and indeed remove such concerns
 476           // from GCH). XXX
 477 
 478           HandleMark hm;  // Discard invalid handles created during gc
 479           save_marks();   // save marks for all gens
 480           // We want to discover references, but not process them yet.
 481           // This mode is disabled in process_discovered_references if the
 482           // generation does some collection work, or in
 483           // enqueue_discovered_references if the generation returns
 484           // without doing any work.
 485           ReferenceProcessor* rp = _gens[i]->ref_processor();
 486           // If the discovery of ("weak") refs in this generation is
 487           // atomic wrt other collectors in this configuration, we
 488           // are guaranteed to have empty discovered ref lists.
 489           if (rp->discovery_is_atomic()) {
 490             rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
 491             rp->setup_policy(do_clear_all_soft_refs);
 492           } else {
 493             // collect() below will enable discovery as appropriate
 494           }
 495           _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
 496           if (!rp->enqueuing_is_done()) {
 497             rp->enqueue_discovered_references();
 498           } else {
 499             rp->set_enqueuing_is_done(false);
 500           }
 501           rp->verify_no_references_recorded();
 502         }
 503         max_level_collected = i;
 504 
 505         // Determine if allocation request was met.
 506         if (size > 0) {
 507           if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
 508             if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
 509               size = 0;
 510             }
 511           }
 512         }
 513 
 514         COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 515 
 516         _gens[i]->stat_record()->accumulated_time.stop();
 517 
 518         update_gc_stats(i, full);
 519 
 520         if (VerifyAfterGC && i >= VerifyGCLevel &&
 521             total_collections() >= VerifyGCStartAt) {
 522           HandleMark hm;  // Discard invalid handles created during verification
 523           Universe::verify(" VerifyAfterGC:");
 524         }
 525 
 526         if (PrintGCDetails) {
 527           gclog_or_tty->print(":");
 528           _gens[i]->print_heap_change(prev_used);
 529         }
 530       }
 531     }
 532 
 533     // Update "complete" boolean wrt what actually transpired --
 534     // for instance, a promotion failure could have led to
 535     // a whole heap collection.
 536     complete = complete || (max_level_collected == n_gens() - 1);
 537 
 538     if (complete) { // We did a "major" collection
 539       // FIXME: See comment at pre_full_gc_dump call
 540       post_full_gc_dump(NULL);   // do any post full gc dumps
 541     }
 542 
 543     if (PrintGCDetails) {
 544       print_heap_change(gch_prev_used);
 545 
 546       // Print metaspace info for full GC with PrintGCDetails flag.
 547       if (complete) {
 548         MetaspaceAux::print_metaspace_change(metadata_prev_used);
 549       }
 550     }
 551 
 552     for (int j = max_level_collected; j >= 0; j -= 1) {
 553       // Adjust generation sizes.
 554       _gens[j]->compute_new_size();
 555     }
 556 
 557     if (complete) {
 558       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 559       ClassLoaderDataGraph::purge();
 560       MetaspaceAux::verify_metrics();
 561       // Resize the metaspace capacity after full collections
 562       MetaspaceGC::compute_new_size();
 563       update_full_collections_completed();
 564     }
 565 
 566     // Track memory usage and detect low memory after GC finishes
 567     MemoryService::track_memory_usage();
 568 
 569     gc_epilogue(complete);
 570 
 571     if (must_restore_marks_for_biased_locking) {
 572       BiasedLocking::restore_marks();
 573     }
 574   }
 575 
 576   AdaptiveSizePolicy* sp = gen_policy()->size_policy();
 577   AdaptiveSizePolicyOutput(sp, total_collections());
 578 
 579   print_heap_after_gc();
 580 
 581 #ifdef TRACESPINNING
 582   ParallelTaskTerminator::print_termination_counts();
 583 #endif
 584 }
 585 
 586 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 587   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 588 }
 589 
 590 void GenCollectedHeap::set_par_threads(uint t) {
 591   SharedHeap::set_par_threads(t);
 592   _gen_process_roots_tasks->set_n_threads(t);
 593 }
 594 
 595 void GenCollectedHeap::
 596 gen_process_roots(int level,
 597                   bool younger_gens_as_roots,
 598                   bool activate_scope,
 599                   SharedHeap::ScanningOption so,
 600                   OopsInGenClosure* not_older_gens,
 601                   OopsInGenClosure* weak_roots,
 602                   OopsInGenClosure* older_gens,
 603                   CLDClosure* cld_closure,
 604                   CLDClosure* weak_cld_closure,
 605                   CodeBlobClosure* code_closure) {
 606 
 607   // General roots.
 608   SharedHeap::process_roots(activate_scope, so,
 609                             not_older_gens, weak_roots,
 610                             cld_closure, weak_cld_closure,
 611                             code_closure);
 612 
 613   if (younger_gens_as_roots) {
 614     if (!_gen_process_roots_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 615       for (int i = 0; i < level; i++) {
 616         not_older_gens->set_generation(_gens[i]);
 617         _gens[i]->oop_iterate(not_older_gens);
 618       }
 619       not_older_gens->reset_generation();
 620     }
 621   }
 622   // When collection is parallel, all threads get to cooperate to do
 623   // older-gen scanning.
 624   for (int i = level+1; i < _n_gens; i++) {
 625     older_gens->set_generation(_gens[i]);
 626     rem_set()->younger_refs_iterate(_gens[i], older_gens);
 627     older_gens->reset_generation();
 628   }
 629 
 630   _gen_process_roots_tasks->all_tasks_completed();
 631 }
 632 
 633 void GenCollectedHeap::
 634 gen_process_roots(int level,
 635                   bool younger_gens_as_roots,
 636                   bool activate_scope,
 637                   SharedHeap::ScanningOption so,
 638                   bool only_strong_roots,
 639                   OopsInGenClosure* not_older_gens,
 640                   OopsInGenClosure* older_gens,
 641                   CLDClosure* cld_closure) {
 642 
 643   const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
 644 
 645   bool is_moving_collection = false;
 646   if (level == 0 || is_adjust_phase) {
 647     // young collections are always moving
 648     is_moving_collection = true;
 649   }
 650 
 651   MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
 652   CodeBlobClosure* code_closure = &mark_code_closure;
 653 
 654   gen_process_roots(level,
 655                     younger_gens_as_roots,
 656                     activate_scope, so,
 657                     not_older_gens, only_strong_roots ? NULL : not_older_gens,
 658                     older_gens,
 659                     cld_closure, only_strong_roots ? NULL : cld_closure,
 660                     code_closure);
 661 
 662 }
 663 
 664 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
 665   SharedHeap::process_weak_roots(root_closure);
 666   // "Local" "weak" refs
 667   for (int i = 0; i < _n_gens; i++) {
 668     _gens[i]->ref_processor()->weak_oops_do(root_closure);
 669   }
 670 }
 671 
 672 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 673 void GenCollectedHeap::                                                 \
 674 oop_since_save_marks_iterate(int level,                                 \
 675                              OopClosureType* cur,                       \
 676                              OopClosureType* older) {                   \
 677   _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur);           \
 678   for (int i = level+1; i < n_gens(); i++) {                            \
 679     _gens[i]->oop_since_save_marks_iterate##nv_suffix(older);           \
 680   }                                                                     \
 681 }
 682 
 683 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 684 
 685 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 686 
 687 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
 688   for (int i = level; i < _n_gens; i++) {
 689     if (!_gens[i]->no_allocs_since_save_marks()) return false;
 690   }
 691   return true;
 692 }
 693 
 694 bool GenCollectedHeap::supports_inline_contig_alloc() const {
 695   return _gens[0]->supports_inline_contig_alloc();
 696 }
 697 
 698 HeapWord** GenCollectedHeap::top_addr() const {
 699   return _gens[0]->top_addr();
 700 }
 701 
 702 HeapWord** GenCollectedHeap::end_addr() const {
 703   return _gens[0]->end_addr();
 704 }
 705 
 706 // public collection interfaces
 707 
 708 void GenCollectedHeap::collect(GCCause::Cause cause) {
 709   if (should_do_concurrent_full_gc(cause)) {
 710 #if INCLUDE_ALL_GCS
 711     // mostly concurrent full collection
 712     collect_mostly_concurrent(cause);
 713 #else  // INCLUDE_ALL_GCS
 714     ShouldNotReachHere();
 715 #endif // INCLUDE_ALL_GCS
 716   } else if (cause == GCCause::_wb_young_gc) {
 717     // minor collection for WhiteBox API
 718     collect(cause, 0);
 719   } else {
 720 #ifdef ASSERT
 721   if (cause == GCCause::_scavenge_alot) {
 722     // minor collection only
 723     collect(cause, 0);
 724   } else {
 725     // Stop-the-world full collection
 726     collect(cause, n_gens() - 1);
 727   }
 728 #else
 729     // Stop-the-world full collection
 730     collect(cause, n_gens() - 1);
 731 #endif
 732   }
 733 }
 734 
 735 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
 736   // The caller doesn't have the Heap_lock
 737   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 738   MutexLocker ml(Heap_lock);
 739   collect_locked(cause, max_level);
 740 }
 741 
 742 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
 743   // The caller has the Heap_lock
 744   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
 745   collect_locked(cause, n_gens() - 1);
 746 }
 747 
 748 // this is the private collection interface
 749 // The Heap_lock is expected to be held on entry.
 750 
 751 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
 752   // Read the GC count while holding the Heap_lock
 753   unsigned int gc_count_before      = total_collections();
 754   unsigned int full_gc_count_before = total_full_collections();
 755   {
 756     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
 757     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
 758                          cause, max_level);
 759     VMThread::execute(&op);
 760   }
 761 }
 762 
 763 #if INCLUDE_ALL_GCS
 764 bool GenCollectedHeap::create_cms_collector() {
 765 
 766   assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
 767          (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)),
 768          "Unexpected generation kinds");
 769   // Skip two header words in the block content verification
 770   NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
 771   CMSCollector* collector = new CMSCollector(
 772     (ConcurrentMarkSweepGeneration*)_gens[1],
 773     _rem_set->as_CardTableRS(),
 774     (ConcurrentMarkSweepPolicy*) collector_policy());
 775 
 776   if (collector == NULL || !collector->completed_initialization()) {
 777     if (collector) {
 778       delete collector;  // Be nice in embedded situation
 779     }
 780     vm_shutdown_during_initialization("Could not create CMS collector");
 781     return false;
 782   }
 783   return true;  // success
 784 }
 785 
 786 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
 787   assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
 788 
 789   MutexLocker ml(Heap_lock);
 790   // Read the GC counts while holding the Heap_lock
 791   unsigned int full_gc_count_before = total_full_collections();
 792   unsigned int gc_count_before      = total_collections();
 793   {
 794     MutexUnlocker mu(Heap_lock);
 795     VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
 796     VMThread::execute(&op);
 797   }
 798 }
 799 #endif // INCLUDE_ALL_GCS
 800 
 801 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
 802    do_full_collection(clear_all_soft_refs, _n_gens - 1);
 803 }
 804 
 805 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 806                                           int max_level) {
 807   int local_max_level;
 808   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 809       gc_cause() == GCCause::_gc_locker) {
 810     local_max_level = 0;
 811   } else {
 812     local_max_level = max_level;
 813   }
 814 
 815   do_collection(true                 /* full */,
 816                 clear_all_soft_refs  /* clear_all_soft_refs */,
 817                 0                    /* size */,
 818                 false                /* is_tlab */,
 819                 local_max_level      /* max_level */);
 820   // Hack XXX FIX ME !!!
 821   // A scavenge may not have been attempted, or may have
 822   // been attempted and failed, because the old gen was too full
 823   if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
 824       incremental_collection_will_fail(false /* don't consult_young */)) {
 825     if (PrintGCDetails) {
 826       gclog_or_tty->print_cr("GC locker: Trying a full collection "
 827                              "because scavenge failed");
 828     }
 829     // This time allow the old gen to be collected as well
 830     do_collection(true                 /* full */,
 831                   clear_all_soft_refs  /* clear_all_soft_refs */,
 832                   0                    /* size */,
 833                   false                /* is_tlab */,
 834                   n_gens() - 1         /* max_level */);
 835   }
 836 }
 837 
 838 bool GenCollectedHeap::is_in_young(oop p) {
 839   bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
 840   assert(result == _gens[0]->is_in_reserved(p),
 841          err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, p2i((void*)p)));
 842   return result;
 843 }
 844 
 845 // Returns "TRUE" iff "p" points into the committed areas of the heap.
 846 bool GenCollectedHeap::is_in(const void* p) const {
 847   #ifndef ASSERT
 848   guarantee(VerifyBeforeGC      ||
 849             VerifyDuringGC      ||
 850             VerifyBeforeExit    ||
 851             VerifyDuringStartup ||
 852             PrintAssembly       ||
 853             tty->count() != 0   ||   // already printing
 854             VerifyAfterGC       ||
 855     VMError::fatal_error_in_progress(), "too expensive");
 856 
 857   #endif
 858   // This might be sped up with a cache of the last generation that
 859   // answered yes.
 860   for (int i = 0; i < _n_gens; i++) {
 861     if (_gens[i]->is_in(p)) return true;
 862   }
 863   // Otherwise...
 864   return false;
 865 }
 866 
 867 #ifdef ASSERT
 868 // Don't implement this by using is_in_young().  This method is used
 869 // in some cases to check that is_in_young() is correct.
 870 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
 871   assert(is_in_reserved(p) || p == NULL,
 872     "Does not work if address is non-null and outside of the heap");
 873   return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
 874 }
 875 #endif
 876 
 877 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
 878   for (int i = 0; i < _n_gens; i++) {
 879     _gens[i]->oop_iterate(cl);
 880   }
 881 }
 882 
 883 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
 884   for (int i = 0; i < _n_gens; i++) {
 885     _gens[i]->object_iterate(cl);
 886   }
 887 }
 888 
 889 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
 890   for (int i = 0; i < _n_gens; i++) {
 891     _gens[i]->safe_object_iterate(cl);
 892   }
 893 }
 894 
 895 Space* GenCollectedHeap::space_containing(const void* addr) const {
 896   for (int i = 0; i < _n_gens; i++) {
 897     Space* res = _gens[i]->space_containing(addr);
 898     if (res != NULL) return res;
 899   }
 900   // Otherwise...
 901   assert(false, "Could not find containing space");
 902   return NULL;
 903 }
 904 
 905 
 906 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
 907   assert(is_in_reserved(addr), "block_start of address outside of heap");
 908   for (int i = 0; i < _n_gens; i++) {
 909     if (_gens[i]->is_in_reserved(addr)) {
 910       assert(_gens[i]->is_in(addr),
 911              "addr should be in allocated part of generation");
 912       return _gens[i]->block_start(addr);
 913     }
 914   }
 915   assert(false, "Some generation should contain the address");
 916   return NULL;
 917 }
 918 
 919 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
 920   assert(is_in_reserved(addr), "block_size of address outside of heap");
 921   for (int i = 0; i < _n_gens; i++) {
 922     if (_gens[i]->is_in_reserved(addr)) {
 923       assert(_gens[i]->is_in(addr),
 924              "addr should be in allocated part of generation");
 925       return _gens[i]->block_size(addr);
 926     }
 927   }
 928   assert(false, "Some generation should contain the address");
 929   return 0;
 930 }
 931 
 932 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
 933   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
 934   assert(block_start(addr) == addr, "addr must be a block start");
 935   for (int i = 0; i < _n_gens; i++) {
 936     if (_gens[i]->is_in_reserved(addr)) {
 937       return _gens[i]->block_is_obj(addr);
 938     }
 939   }
 940   assert(false, "Some generation should contain the address");
 941   return false;
 942 }
 943 
 944 bool GenCollectedHeap::supports_tlab_allocation() const {
 945   for (int i = 0; i < _n_gens; i += 1) {
 946     if (_gens[i]->supports_tlab_allocation()) {
 947       return true;
 948     }
 949   }
 950   return false;
 951 }
 952 
 953 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
 954   size_t result = 0;
 955   for (int i = 0; i < _n_gens; i += 1) {
 956     if (_gens[i]->supports_tlab_allocation()) {
 957       result += _gens[i]->tlab_capacity();
 958     }
 959   }
 960   return result;
 961 }
 962 
 963 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
 964   size_t result = 0;
 965   for (int i = 0; i < _n_gens; i += 1) {
 966     if (_gens[i]->supports_tlab_allocation()) {
 967       result += _gens[i]->tlab_used();
 968     }
 969   }
 970   return result;
 971 }
 972 
 973 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
 974   size_t result = 0;
 975   for (int i = 0; i < _n_gens; i += 1) {
 976     if (_gens[i]->supports_tlab_allocation()) {
 977       result += _gens[i]->unsafe_max_tlab_alloc();
 978     }
 979   }
 980   return result;
 981 }
 982 
 983 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
 984   bool gc_overhead_limit_was_exceeded;
 985   return collector_policy()->mem_allocate_work(size /* size */,
 986                                                true /* is_tlab */,
 987                                                &gc_overhead_limit_was_exceeded);
 988 }
 989 
 990 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
 991 // from the list headed by "*prev_ptr".
 992 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
 993   bool first = true;
 994   size_t min_size = 0;   // "first" makes this conceptually infinite.
 995   ScratchBlock **smallest_ptr, *smallest;
 996   ScratchBlock  *cur = *prev_ptr;
 997   while (cur) {
 998     assert(*prev_ptr == cur, "just checking");
 999     if (first || cur->num_words < min_size) {
1000       smallest_ptr = prev_ptr;
1001       smallest     = cur;
1002       min_size     = smallest->num_words;
1003       first        = false;
1004     }
1005     prev_ptr = &cur->next;
1006     cur     =  cur->next;
1007   }
1008   smallest      = *smallest_ptr;
1009   *smallest_ptr = smallest->next;
1010   return smallest;
1011 }
1012 
1013 // Sort the scratch block list headed by res into decreasing size order,
1014 // and set "res" to the result.
1015 static void sort_scratch_list(ScratchBlock*& list) {
1016   ScratchBlock* sorted = NULL;
1017   ScratchBlock* unsorted = list;
1018   while (unsorted) {
1019     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1020     smallest->next  = sorted;
1021     sorted          = smallest;
1022   }
1023   list = sorted;
1024 }
1025 
1026 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1027                                                size_t max_alloc_words) {
1028   ScratchBlock* res = NULL;
1029   for (int i = 0; i < _n_gens; i++) {
1030     _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1031   }
1032   sort_scratch_list(res);
1033   return res;
1034 }
1035 
1036 void GenCollectedHeap::release_scratch() {
1037   for (int i = 0; i < _n_gens; i++) {
1038     _gens[i]->reset_scratch();
1039   }
1040 }
1041 
1042 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1043   void do_generation(Generation* gen) {
1044     gen->prepare_for_verify();
1045   }
1046 };
1047 
1048 void GenCollectedHeap::prepare_for_verify() {
1049   ensure_parsability(false);        // no need to retire TLABs
1050   GenPrepareForVerifyClosure blk;
1051   generation_iterate(&blk, false);
1052 }
1053 
1054 
1055 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1056                                           bool old_to_young) {
1057   if (old_to_young) {
1058     for (int i = _n_gens-1; i >= 0; i--) {
1059       cl->do_generation(_gens[i]);
1060     }
1061   } else {
1062     for (int i = 0; i < _n_gens; i++) {
1063       cl->do_generation(_gens[i]);
1064     }
1065   }
1066 }
1067 
1068 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1069   for (int i = 0; i < _n_gens; i++) {
1070     _gens[i]->space_iterate(cl, true);
1071   }
1072 }
1073 
1074 bool GenCollectedHeap::is_maximal_no_gc() const {
1075   for (int i = 0; i < _n_gens; i++) {
1076     if (!_gens[i]->is_maximal_no_gc()) {
1077       return false;
1078     }
1079   }
1080   return true;
1081 }
1082 
1083 void GenCollectedHeap::save_marks() {
1084   for (int i = 0; i < _n_gens; i++) {
1085     _gens[i]->save_marks();
1086   }
1087 }
1088 
1089 GenCollectedHeap* GenCollectedHeap::heap() {
1090   assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1091   assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1092   return _gch;
1093 }
1094 
1095 
1096 void GenCollectedHeap::prepare_for_compaction() {
1097   guarantee(_n_gens = 2, "Wrong number of generations");
1098   Generation* old_gen = _gens[1];
1099   // Start by compacting into same gen.
1100   CompactPoint cp(old_gen);
1101   old_gen->prepare_for_compaction(&cp);
1102   Generation* young_gen = _gens[0];
1103   young_gen->prepare_for_compaction(&cp);
1104 }
1105 
1106 GCStats* GenCollectedHeap::gc_stats(int level) const {
1107   return _gens[level]->gc_stats();
1108 }
1109 
1110 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1111   for (int i = _n_gens-1; i >= 0; i--) {
1112     Generation* g = _gens[i];
1113     if (!silent) {
1114       gclog_or_tty->print("%s", g->name());
1115       gclog_or_tty->print(" ");
1116     }
1117     g->verify();
1118   }
1119   if (!silent) {
1120     gclog_or_tty->print("remset ");
1121   }
1122   rem_set()->verify();
1123 }
1124 
1125 void GenCollectedHeap::print_on(outputStream* st) const {
1126   for (int i = 0; i < _n_gens; i++) {
1127     _gens[i]->print_on(st);
1128   }
1129   MetaspaceAux::print_on(st);
1130 }
1131 
1132 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1133   if (workers() != NULL) {
1134     workers()->threads_do(tc);
1135   }
1136 #if INCLUDE_ALL_GCS
1137   if (UseConcMarkSweepGC) {
1138     ConcurrentMarkSweepThread::threads_do(tc);
1139   }
1140 #endif // INCLUDE_ALL_GCS
1141 }
1142 
1143 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1144 #if INCLUDE_ALL_GCS
1145   if (UseParNewGC) {
1146     workers()->print_worker_threads_on(st);
1147   }
1148   if (UseConcMarkSweepGC) {
1149     ConcurrentMarkSweepThread::print_all_on(st);
1150   }
1151 #endif // INCLUDE_ALL_GCS
1152 }
1153 
1154 void GenCollectedHeap::print_on_error(outputStream* st) const {
1155   this->CollectedHeap::print_on_error(st);
1156 
1157 #if INCLUDE_ALL_GCS
1158   if (UseConcMarkSweepGC) {
1159     st->cr();
1160     CMSCollector::print_on_error(st);
1161   }
1162 #endif // INCLUDE_ALL_GCS
1163 }
1164 
1165 void GenCollectedHeap::print_tracing_info() const {
1166   if (TraceGen0Time) {
1167     get_gen(0)->print_summary_info();
1168   }
1169   if (TraceGen1Time) {
1170     get_gen(1)->print_summary_info();
1171   }
1172 }
1173 
1174 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1175   if (PrintGCDetails && Verbose) {
1176     gclog_or_tty->print(" "  SIZE_FORMAT
1177                         "->" SIZE_FORMAT
1178                         "("  SIZE_FORMAT ")",
1179                         prev_used, used(), capacity());
1180   } else {
1181     gclog_or_tty->print(" "  SIZE_FORMAT "K"
1182                         "->" SIZE_FORMAT "K"
1183                         "("  SIZE_FORMAT "K)",
1184                         prev_used / K, used() / K, capacity() / K);
1185   }
1186 }
1187 
1188 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1189  private:
1190   bool _full;
1191  public:
1192   void do_generation(Generation* gen) {
1193     gen->gc_prologue(_full);
1194   }
1195   GenGCPrologueClosure(bool full) : _full(full) {};
1196 };
1197 
1198 void GenCollectedHeap::gc_prologue(bool full) {
1199   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1200 
1201   always_do_update_barrier = false;
1202   // Fill TLAB's and such
1203   CollectedHeap::accumulate_statistics_all_tlabs();
1204   ensure_parsability(true);   // retire TLABs
1205 
1206   // Walk generations
1207   GenGCPrologueClosure blk(full);
1208   generation_iterate(&blk, false);  // not old-to-young.
1209 };
1210 
1211 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1212  private:
1213   bool _full;
1214  public:
1215   void do_generation(Generation* gen) {
1216     gen->gc_epilogue(_full);
1217   }
1218   GenGCEpilogueClosure(bool full) : _full(full) {};
1219 };
1220 
1221 void GenCollectedHeap::gc_epilogue(bool full) {
1222 #ifdef COMPILER2
1223   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1224   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1225   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1226 #endif /* COMPILER2 */
1227 
1228   resize_all_tlabs();
1229 
1230   GenGCEpilogueClosure blk(full);
1231   generation_iterate(&blk, false);  // not old-to-young.
1232 
1233   if (!CleanChunkPoolAsync) {
1234     Chunk::clean_chunk_pool();
1235   }
1236 
1237   MetaspaceCounters::update_performance_counters();
1238   CompressedClassSpaceCounters::update_performance_counters();
1239 
1240   always_do_update_barrier = UseConcMarkSweepGC;
1241 };
1242 
1243 #ifndef PRODUCT
1244 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1245  private:
1246  public:
1247   void do_generation(Generation* gen) {
1248     gen->record_spaces_top();
1249   }
1250 };
1251 
1252 void GenCollectedHeap::record_gen_tops_before_GC() {
1253   if (ZapUnusedHeapArea) {
1254     GenGCSaveTopsBeforeGCClosure blk;
1255     generation_iterate(&blk, false);  // not old-to-young.
1256   }
1257 }
1258 #endif  // not PRODUCT
1259 
1260 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1261  public:
1262   void do_generation(Generation* gen) {
1263     gen->ensure_parsability();
1264   }
1265 };
1266 
1267 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1268   CollectedHeap::ensure_parsability(retire_tlabs);
1269   GenEnsureParsabilityClosure ep_cl;
1270   generation_iterate(&ep_cl, false);
1271 }
1272 
1273 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1274                                               oop obj,
1275                                               size_t obj_size) {
1276   guarantee(old_gen->level() == 1, "We only get here with an old generation");
1277   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1278   HeapWord* result = NULL;
1279 
1280   result = old_gen->expand_and_allocate(obj_size, false);
1281 
1282   if (result != NULL) {
1283     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1284   }
1285   return oop(result);
1286 }
1287 
1288 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1289   jlong _time;   // in ms
1290   jlong _now;    // in ms
1291 
1292  public:
1293   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1294 
1295   jlong time() { return _time; }
1296 
1297   void do_generation(Generation* gen) {
1298     _time = MIN2(_time, gen->time_of_last_gc(_now));
1299   }
1300 };
1301 
1302 jlong GenCollectedHeap::millis_since_last_gc() {
1303   // We need a monotonically non-deccreasing time in ms but
1304   // os::javaTimeMillis() does not guarantee monotonicity.
1305   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1306   GenTimeOfLastGCClosure tolgc_cl(now);
1307   // iterate over generations getting the oldest
1308   // time that a generation was collected
1309   generation_iterate(&tolgc_cl, false);
1310 
1311   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1312   // provided the underlying platform provides such a time source
1313   // (and it is bug free). So we still have to guard against getting
1314   // back a time later than 'now'.
1315   jlong retVal = now - tolgc_cl.time();
1316   if (retVal < 0) {
1317     NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1318     return 0;
1319   }
1320   return retVal;
1321 }