1 /*
   2  * Copyright (c) 2000, 2013, 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/gcTraceTime.hpp"
  32 #include "gc_implementation/shared/vmGCOperations.hpp"
  33 #include "gc_interface/collectedHeap.inline.hpp"
  34 #include "memory/filemap.hpp"
  35 #include "memory/gcLocker.inline.hpp"
  36 #include "memory/genCollectedHeap.hpp"
  37 #include "memory/genOopClosures.inline.hpp"
  38 #include "memory/generation.inline.hpp"
  39 #include "memory/generationSpec.hpp"
  40 #include "memory/resourceArea.hpp"
  41 #include "memory/sharedHeap.hpp"
  42 #include "memory/space.hpp"
  43 #include "oops/oop.inline.hpp"
  44 #include "oops/oop.inline2.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/memoryService.hpp"
  52 #include "utilities/vmError.hpp"
  53 #include "utilities/workgroup.hpp"
  54 #include "utilities/macros.hpp"
  55 #if INCLUDE_ALL_GCS
  56 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  57 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
  58 #endif // INCLUDE_ALL_GCS
  59 
  60 GenCollectedHeap* GenCollectedHeap::_gch;
  61 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
  62 
  63 // The set of potentially parallel tasks in strong root scanning.
  64 enum GCH_process_strong_roots_tasks {
  65   // We probably want to parallelize both of these internally, but for now...
  66   GCH_PS_younger_gens,
  67   // Leave this one last.
  68   GCH_PS_NumElements
  69 };
  70 
  71 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
  72   SharedHeap(policy),
  73   _gen_policy(policy),
  74   _gen_process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
  75   _full_collections_completed(0)
  76 {
  77   if (_gen_process_strong_tasks == NULL ||
  78       !_gen_process_strong_tasks->valid()) {
  79     vm_exit_during_initialization("Failed necessary allocation.");
  80   }
  81   assert(policy != NULL, "Sanity check");
  82 }
  83 
  84 jint GenCollectedHeap::initialize() {
  85   CollectedHeap::pre_initialize();
  86 
  87   int i;
  88   _n_gens = gen_policy()->number_of_generations();
  89 
  90   // While there are no constraints in the GC code that HeapWordSize
  91   // be any particular value, there are multiple other areas in the
  92   // system which believe this to be true (e.g. oop->object_size in some
  93   // cases incorrectly returns the size in wordSize units rather than
  94   // HeapWordSize).
  95   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
  96 
  97   // The heap must be at least as aligned as generations.
  98   size_t alignment = Generation::GenGrain;
  99 
 100   _gen_specs = gen_policy()->generations();
 101 
 102   // Make sure the sizes are all aligned.
 103   for (i = 0; i < _n_gens; i++) {
 104     _gen_specs[i]->align(alignment);
 105   }
 106 
 107   // Allocate space for the heap.
 108 
 109   char* heap_address;
 110   size_t total_reserved = 0;
 111   int n_covered_regions = 0;
 112   ReservedSpace heap_rs(0);
 113 
 114   heap_address = allocate(alignment, &total_reserved,
 115                           &n_covered_regions, &heap_rs);
 116 
 117   if (!heap_rs.is_reserved()) {
 118     vm_shutdown_during_initialization(
 119       "Could not reserve enough space for object heap");
 120     return JNI_ENOMEM;
 121   }
 122 
 123   _reserved = MemRegion((HeapWord*)heap_rs.base(),
 124                         (HeapWord*)(heap_rs.base() + heap_rs.size()));
 125 
 126   // It is important to do this in a way such that concurrent readers can't
 127   // temporarily think somethings in the heap.  (Seen this happen in asserts.)
 128   _reserved.set_word_size(0);
 129   _reserved.set_start((HeapWord*)heap_rs.base());
 130   size_t actual_heap_size = heap_rs.size();
 131   _reserved.set_end((HeapWord*)(heap_rs.base() + actual_heap_size));
 132 
 133   _rem_set = collector_policy()->create_rem_set(_reserved, n_covered_regions);
 134   set_barrier_set(rem_set()->bs());
 135 
 136   _gch = this;
 137 
 138   for (i = 0; i < _n_gens; i++) {
 139     ReservedSpace this_rs = heap_rs.first_part(_gen_specs[i]->max_size(), false, false);
 140     _gens[i] = _gen_specs[i]->init(this_rs, i, rem_set());
 141     heap_rs = heap_rs.last_part(_gen_specs[i]->max_size());
 142   }
 143   clear_incremental_collection_failed();
 144 
 145 #if INCLUDE_ALL_GCS
 146   // If we are running CMS, create the collector responsible
 147   // for collecting the CMS generations.
 148   if (collector_policy()->is_concurrent_mark_sweep_policy()) {
 149     bool success = create_cms_collector();
 150     if (!success) return JNI_ENOMEM;
 151   }
 152 #endif // INCLUDE_ALL_GCS
 153 
 154   return JNI_OK;
 155 }
 156 
 157 
 158 char* GenCollectedHeap::allocate(size_t alignment,
 159                                  size_t* _total_reserved,
 160                                  int* _n_covered_regions,
 161                                  ReservedSpace* heap_rs){
 162   const char overflow_msg[] = "The size of the object heap + VM data exceeds "
 163     "the maximum representable size";
 164 
 165   // Now figure out the total size.
 166   size_t total_reserved = 0;
 167   int n_covered_regions = 0;
 168   const size_t pageSize = UseLargePages ?
 169       os::large_page_size() : os::vm_page_size();
 170 
 171   for (int i = 0; i < _n_gens; i++) {
 172     total_reserved += _gen_specs[i]->max_size();
 173     if (total_reserved < _gen_specs[i]->max_size()) {
 174       vm_exit_during_initialization(overflow_msg);
 175     }
 176     n_covered_regions += _gen_specs[i]->n_covered_regions();
 177   }
 178   assert(total_reserved % pageSize == 0,
 179          err_msg("Gen size; total_reserved=" SIZE_FORMAT ", pageSize="
 180                  SIZE_FORMAT, total_reserved, pageSize));
 181 
 182   // Needed until the cardtable is fixed to have the right number
 183   // of covered regions.
 184   n_covered_regions += 2;
 185 
 186   if (UseLargePages) {
 187     assert(total_reserved != 0, "total_reserved cannot be 0");
 188     total_reserved = round_to(total_reserved, os::large_page_size());
 189     if (total_reserved < os::large_page_size()) {
 190       vm_exit_during_initialization(overflow_msg);
 191     }
 192   }
 193 
 194       *_total_reserved = total_reserved;
 195       *_n_covered_regions = n_covered_regions;
 196   *heap_rs = Universe::reserve_heap(total_reserved, alignment);
 197   return heap_rs->base();
 198 }
 199 
 200 
 201 void GenCollectedHeap::post_initialize() {
 202   SharedHeap::post_initialize();
 203   TwoGenerationCollectorPolicy *policy =
 204     (TwoGenerationCollectorPolicy *)collector_policy();
 205   guarantee(policy->is_two_generation_policy(), "Illegal policy type");
 206   DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
 207   assert(def_new_gen->kind() == Generation::DefNew ||
 208          def_new_gen->kind() == Generation::ParNew ||
 209          def_new_gen->kind() == Generation::ASParNew,
 210          "Wrong generation kind");
 211 
 212   Generation* old_gen = get_gen(1);
 213   assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
 214          old_gen->kind() == Generation::ASConcurrentMarkSweep ||
 215          old_gen->kind() == Generation::MarkSweepCompact,
 216     "Wrong generation kind");
 217 
 218   policy->initialize_size_policy(def_new_gen->eden()->capacity(),
 219                                  old_gen->capacity(),
 220                                  def_new_gen->from()->capacity());
 221   policy->initialize_gc_policy_counters();
 222 }
 223 
 224 void GenCollectedHeap::ref_processing_init() {
 225   SharedHeap::ref_processing_init();
 226   for (int i = 0; i < _n_gens; i++) {
 227     _gens[i]->ref_processor_init();
 228   }
 229 }
 230 
 231 size_t GenCollectedHeap::capacity() const {
 232   size_t res = 0;
 233   for (int i = 0; i < _n_gens; i++) {
 234     res += _gens[i]->capacity();
 235   }
 236   return res;
 237 }
 238 
 239 size_t GenCollectedHeap::used() const {
 240   size_t res = 0;
 241   for (int i = 0; i < _n_gens; i++) {
 242     res += _gens[i]->used();
 243   }
 244   return res;
 245 }
 246 
 247 // Save the "used_region" for generations level and lower.
 248 void GenCollectedHeap::save_used_regions(int level) {
 249   assert(level < _n_gens, "Illegal level parameter");
 250   for (int i = level; i >= 0; i--) {
 251     _gens[i]->save_used_region();
 252   }
 253 }
 254 
 255 size_t GenCollectedHeap::max_capacity() const {
 256   size_t res = 0;
 257   for (int i = 0; i < _n_gens; i++) {
 258     res += _gens[i]->max_capacity();
 259   }
 260   return res;
 261 }
 262 
 263 // Update the _full_collections_completed counter
 264 // at the end of a stop-world full GC.
 265 unsigned int GenCollectedHeap::update_full_collections_completed() {
 266   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 267   assert(_full_collections_completed <= _total_full_collections,
 268          "Can't complete more collections than were started");
 269   _full_collections_completed = _total_full_collections;
 270   ml.notify_all();
 271   return _full_collections_completed;
 272 }
 273 
 274 // Update the _full_collections_completed counter, as appropriate,
 275 // at the end of a concurrent GC cycle. Note the conditional update
 276 // below to allow this method to be called by a concurrent collector
 277 // without synchronizing in any manner with the VM thread (which
 278 // may already have initiated a STW full collection "concurrently").
 279 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
 280   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 281   assert((_full_collections_completed <= _total_full_collections) &&
 282          (count <= _total_full_collections),
 283          "Can't complete more collections than were started");
 284   if (count > _full_collections_completed) {
 285     _full_collections_completed = count;
 286     ml.notify_all();
 287   }
 288   return _full_collections_completed;
 289 }
 290 
 291 
 292 #ifndef PRODUCT
 293 // Override of memory state checking method in CollectedHeap:
 294 // Some collectors (CMS for example) can't have badHeapWordVal written
 295 // in the first two words of an object. (For instance , in the case of
 296 // CMS these words hold state used to synchronize between certain
 297 // (concurrent) GC steps and direct allocating mutators.)
 298 // The skip_header_HeapWords() method below, allows us to skip
 299 // over the requisite number of HeapWord's. Note that (for
 300 // generational collectors) this means that those many words are
 301 // skipped in each object, irrespective of the generation in which
 302 // that object lives. The resultant loss of precision seems to be
 303 // harmless and the pain of avoiding that imprecision appears somewhat
 304 // higher than we are prepared to pay for such rudimentary debugging
 305 // support.
 306 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
 307                                                          size_t size) {
 308   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 309     // We are asked to check a size in HeapWords,
 310     // but the memory is mangled in juint words.
 311     juint* start = (juint*) (addr + skip_header_HeapWords());
 312     juint* end   = (juint*) (addr + size);
 313     for (juint* slot = start; slot < end; slot += 1) {
 314       assert(*slot == badHeapWordVal,
 315              "Found non badHeapWordValue in pre-allocation check");
 316     }
 317   }
 318 }
 319 #endif
 320 
 321 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
 322                                                bool is_tlab,
 323                                                bool first_only) {
 324   HeapWord* res;
 325   for (int i = 0; i < _n_gens; i++) {
 326     if (_gens[i]->should_allocate(size, is_tlab)) {
 327       res = _gens[i]->allocate(size, is_tlab);
 328       if (res != NULL) return res;
 329       else if (first_only) break;
 330     }
 331   }
 332   // Otherwise...
 333   return NULL;
 334 }
 335 
 336 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
 337                                          bool* gc_overhead_limit_was_exceeded) {
 338   return collector_policy()->mem_allocate_work(size,
 339                                                false /* is_tlab */,
 340                                                gc_overhead_limit_was_exceeded);
 341 }
 342 
 343 bool GenCollectedHeap::must_clear_all_soft_refs() {
 344   return _gc_cause == GCCause::_last_ditch_collection;
 345 }
 346 
 347 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
 348   return UseConcMarkSweepGC &&
 349          ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
 350           (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
 351 }
 352 
 353 void GenCollectedHeap::do_collection(bool  full,
 354                                      bool   clear_all_soft_refs,
 355                                      size_t size,
 356                                      bool   is_tlab,
 357                                      int    max_level) {
 358   bool prepared_for_verification = false;
 359   ResourceMark rm;
 360   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 361 
 362   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 363   assert(my_thread->is_VM_thread() ||
 364          my_thread->is_ConcurrentGC_thread(),
 365          "incorrect thread type capability");
 366   assert(Heap_lock->is_locked(),
 367          "the requesting thread should have the Heap_lock");
 368   guarantee(!is_gc_active(), "collection is not reentrant");
 369   assert(max_level < n_gens(), "sanity check");
 370 
 371   if (GC_locker::check_active_before_gc()) {
 372     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 373   }
 374 
 375   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 376                           collector_policy()->should_clear_all_soft_refs();
 377 
 378   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 379 
 380   const size_t metadata_prev_used = MetaspaceAux::allocated_used_bytes();
 381 
 382   print_heap_before_gc();
 383 
 384   {
 385     FlagSetting fl(_is_gc_active, true);
 386 
 387     bool complete = full && (max_level == (n_gens()-1));
 388     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 389     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
 390     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 391     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL);
 392 
 393     gc_prologue(complete);
 394     increment_total_collections(complete);
 395 
 396     size_t gch_prev_used = used();
 397 
 398     int starting_level = 0;
 399     if (full) {
 400       // Search for the oldest generation which will collect all younger
 401       // generations, and start collection loop there.
 402       for (int i = max_level; i >= 0; i--) {
 403         if (_gens[i]->full_collects_younger_generations()) {
 404           starting_level = i;
 405           break;
 406         }
 407       }
 408     }
 409 
 410     bool must_restore_marks_for_biased_locking = false;
 411 
 412     int max_level_collected = starting_level;
 413     for (int i = starting_level; i <= max_level; i++) {
 414       if (_gens[i]->should_collect(full, size, is_tlab)) {
 415         if (i == n_gens() - 1) {  // a major collection is to happen
 416           if (!complete) {
 417             // The full_collections increment was missed above.
 418             increment_total_full_collections();
 419           }
 420           pre_full_gc_dump(NULL);    // do any pre full gc dumps
 421         }
 422         // Timer for individual generations. Last argument is false: no CR
 423         // FIXME: We should try to start the timing earlier to cover more of the GC pause
 424         GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL);
 425         TraceCollectorStats tcs(_gens[i]->counters());
 426         TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
 427 
 428         size_t prev_used = _gens[i]->used();
 429         _gens[i]->stat_record()->invocations++;
 430         _gens[i]->stat_record()->accumulated_time.start();
 431 
 432         // Must be done anew before each collection because
 433         // a previous collection will do mangling and will
 434         // change top of some spaces.
 435         record_gen_tops_before_GC();
 436 
 437         if (PrintGC && Verbose) {
 438           gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
 439                      i,
 440                      _gens[i]->stat_record()->invocations,
 441                      size*HeapWordSize);
 442         }
 443 
 444         if (VerifyBeforeGC && i >= VerifyGCLevel &&
 445             total_collections() >= VerifyGCStartAt) {
 446           HandleMark hm;  // Discard invalid handles created during verification
 447           if (!prepared_for_verification) {
 448             prepare_for_verify();
 449             prepared_for_verification = true;
 450           }
 451           Universe::verify(" VerifyBeforeGC:");
 452         }
 453         COMPILER2_PRESENT(DerivedPointerTable::clear());
 454 
 455         if (!must_restore_marks_for_biased_locking &&
 456             _gens[i]->performs_in_place_marking()) {
 457           // We perform this mark word preservation work lazily
 458           // because it's only at this point that we know whether we
 459           // absolutely have to do it; we want to avoid doing it for
 460           // scavenge-only collections where it's unnecessary
 461           must_restore_marks_for_biased_locking = true;
 462           BiasedLocking::preserve_marks();
 463         }
 464 
 465         // Do collection work
 466         {
 467           // Note on ref discovery: For what appear to be historical reasons,
 468           // GCH enables and disabled (by enqueing) refs discovery.
 469           // In the future this should be moved into the generation's
 470           // collect method so that ref discovery and enqueueing concerns
 471           // are local to a generation. The collect method could return
 472           // an appropriate indication in the case that notification on
 473           // the ref lock was needed. This will make the treatment of
 474           // weak refs more uniform (and indeed remove such concerns
 475           // from GCH). XXX
 476 
 477           HandleMark hm;  // Discard invalid handles created during gc
 478           save_marks();   // save marks for all gens
 479           // We want to discover references, but not process them yet.
 480           // This mode is disabled in process_discovered_references if the
 481           // generation does some collection work, or in
 482           // enqueue_discovered_references if the generation returns
 483           // without doing any work.
 484           ReferenceProcessor* rp = _gens[i]->ref_processor();
 485           // If the discovery of ("weak") refs in this generation is
 486           // atomic wrt other collectors in this configuration, we
 487           // are guaranteed to have empty discovered ref lists.
 488           if (rp->discovery_is_atomic()) {
 489             rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
 490             rp->setup_policy(do_clear_all_soft_refs);
 491           } else {
 492             // collect() below will enable discovery as appropriate
 493           }
 494           _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
 495           if (!rp->enqueuing_is_done()) {
 496             rp->enqueue_discovered_references();
 497           } else {
 498             rp->set_enqueuing_is_done(false);
 499           }
 500           rp->verify_no_references_recorded();
 501         }
 502         max_level_collected = i;
 503 
 504         // Determine if allocation request was met.
 505         if (size > 0) {
 506           if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
 507             if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
 508               size = 0;
 509             }
 510           }
 511         }
 512 
 513         COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 514 
 515         _gens[i]->stat_record()->accumulated_time.stop();
 516 
 517         update_gc_stats(i, full);
 518 
 519         if (VerifyAfterGC && i >= VerifyGCLevel &&
 520             total_collections() >= VerifyGCStartAt) {
 521           HandleMark hm;  // Discard invalid handles created during verification
 522           Universe::verify(" VerifyAfterGC:");
 523         }
 524 
 525         if (PrintGCDetails) {
 526           gclog_or_tty->print(":");
 527           _gens[i]->print_heap_change(prev_used);
 528         }
 529       }
 530     }
 531 
 532     // Update "complete" boolean wrt what actually transpired --
 533     // for instance, a promotion failure could have led to
 534     // a whole heap collection.
 535     complete = complete || (max_level_collected == n_gens() - 1);
 536 
 537     if (complete) { // We did a "major" collection
 538       // FIXME: See comment at pre_full_gc_dump call
 539       post_full_gc_dump(NULL);   // do any post full gc dumps
 540     }
 541 
 542     if (PrintGCDetails) {
 543       print_heap_change(gch_prev_used);
 544 
 545       // Print metaspace info for full GC with PrintGCDetails flag.
 546       if (complete) {
 547         MetaspaceAux::print_metaspace_change(metadata_prev_used);
 548       }
 549     }
 550 
 551     for (int j = max_level_collected; j >= 0; j -= 1) {
 552       // Adjust generation sizes.
 553       _gens[j]->compute_new_size();
 554     }
 555 
 556     if (complete) {
 557       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 558       ClassLoaderDataGraph::purge();
 559       MetaspaceAux::verify_metrics();
 560       // Resize the metaspace capacity after full collections
 561       MetaspaceGC::compute_new_size();
 562       update_full_collections_completed();
 563     }
 564 
 565     // Track memory usage and detect low memory after GC finishes
 566     MemoryService::track_memory_usage();
 567 
 568     gc_epilogue(complete);
 569 
 570     if (must_restore_marks_for_biased_locking) {
 571       BiasedLocking::restore_marks();
 572     }
 573   }
 574 
 575   AdaptiveSizePolicy* sp = gen_policy()->size_policy();
 576   AdaptiveSizePolicyOutput(sp, total_collections());
 577 
 578   print_heap_after_gc();
 579 
 580 #ifdef TRACESPINNING
 581   ParallelTaskTerminator::print_termination_counts();
 582 #endif
 583 }
 584 
 585 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 586   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 587 }
 588 
 589 void GenCollectedHeap::set_par_threads(uint t) {
 590   SharedHeap::set_par_threads(t);
 591   _gen_process_strong_tasks->set_n_threads(t);
 592 }
 593 
 594 void GenCollectedHeap::
 595 gen_process_strong_roots(int level,
 596                          bool younger_gens_as_roots,
 597                          bool activate_scope,
 598                          bool is_scavenging,
 599                          SharedHeap::ScanningOption so,
 600                          OopsInGenClosure* not_older_gens,
 601                          bool do_code_roots,
 602                          OopsInGenClosure* older_gens,
 603                          KlassClosure* klass_closure) {
 604   // General strong roots.
 605 
 606   if (!do_code_roots) {
 607     SharedHeap::process_strong_roots(activate_scope, is_scavenging, so,
 608                                      not_older_gens, NULL, klass_closure);
 609   } else {
 610     bool do_code_marking = (activate_scope || nmethod::oops_do_marking_is_active());
 611     CodeBlobToOopClosure code_roots(not_older_gens, /*do_marking=*/ do_code_marking);
 612     SharedHeap::process_strong_roots(activate_scope, is_scavenging, so,
 613                                      not_older_gens, &code_roots, klass_closure);
 614   }
 615 
 616   if (younger_gens_as_roots) {
 617     if (!_gen_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 618       for (int i = 0; i < level; i++) {
 619         not_older_gens->set_generation(_gens[i]);
 620         _gens[i]->oop_iterate(not_older_gens);
 621       }
 622       not_older_gens->reset_generation();
 623     }
 624   }
 625   // When collection is parallel, all threads get to cooperate to do
 626   // older-gen scanning.
 627   for (int i = level+1; i < _n_gens; i++) {
 628     older_gens->set_generation(_gens[i]);
 629     rem_set()->younger_refs_iterate(_gens[i], older_gens);
 630     older_gens->reset_generation();
 631   }
 632 
 633   _gen_process_strong_tasks->all_tasks_completed();
 634 }
 635 
 636 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure,
 637                                               CodeBlobClosure* code_roots) {
 638   SharedHeap::process_weak_roots(root_closure, code_roots);
 639   // "Local" "weak" refs
 640   for (int i = 0; i < _n_gens; i++) {
 641     _gens[i]->ref_processor()->weak_oops_do(root_closure);
 642   }
 643 }
 644 
 645 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 646 void GenCollectedHeap::                                                 \
 647 oop_since_save_marks_iterate(int level,                                 \
 648                              OopClosureType* cur,                       \
 649                              OopClosureType* older) {                   \
 650   _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur);           \
 651   for (int i = level+1; i < n_gens(); i++) {                            \
 652     _gens[i]->oop_since_save_marks_iterate##nv_suffix(older);           \
 653   }                                                                     \
 654 }
 655 
 656 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 657 
 658 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 659 
 660 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
 661   for (int i = level; i < _n_gens; i++) {
 662     if (!_gens[i]->no_allocs_since_save_marks()) return false;
 663   }
 664   return true;
 665 }
 666 
 667 bool GenCollectedHeap::supports_inline_contig_alloc() const {
 668   return _gens[0]->supports_inline_contig_alloc();
 669 }
 670 
 671 HeapWord** GenCollectedHeap::top_addr() const {
 672   return _gens[0]->top_addr();
 673 }
 674 
 675 HeapWord** GenCollectedHeap::end_addr() const {
 676   return _gens[0]->end_addr();
 677 }
 678 
 679 size_t GenCollectedHeap::unsafe_max_alloc() {
 680   return _gens[0]->unsafe_max_alloc_nogc();
 681 }
 682 
 683 // public collection interfaces
 684 
 685 void GenCollectedHeap::collect(GCCause::Cause cause) {
 686   if (should_do_concurrent_full_gc(cause)) {
 687 #if INCLUDE_ALL_GCS
 688     // mostly concurrent full collection
 689     collect_mostly_concurrent(cause);
 690 #else  // INCLUDE_ALL_GCS
 691     ShouldNotReachHere();
 692 #endif // INCLUDE_ALL_GCS
 693   } else {
 694 #ifdef ASSERT
 695     if (cause == GCCause::_scavenge_alot) {
 696       // minor collection only
 697       collect(cause, 0);
 698     } else {
 699       // Stop-the-world full collection
 700       collect(cause, n_gens() - 1);
 701     }
 702 #else
 703     // Stop-the-world full collection
 704     collect(cause, n_gens() - 1);
 705 #endif
 706   }
 707 }
 708 
 709 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
 710   // The caller doesn't have the Heap_lock
 711   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 712   MutexLocker ml(Heap_lock);
 713   collect_locked(cause, max_level);
 714 }
 715 
 716 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
 717   // The caller has the Heap_lock
 718   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
 719   collect_locked(cause, n_gens() - 1);
 720 }
 721 
 722 // this is the private collection interface
 723 // The Heap_lock is expected to be held on entry.
 724 
 725 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
 726   // Read the GC count while holding the Heap_lock
 727   unsigned int gc_count_before      = total_collections();
 728   unsigned int full_gc_count_before = total_full_collections();
 729   {
 730     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
 731     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
 732                          cause, max_level);
 733     VMThread::execute(&op);
 734   }
 735 }
 736 
 737 #if INCLUDE_ALL_GCS
 738 bool GenCollectedHeap::create_cms_collector() {
 739 
 740   assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
 741          (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)),
 742          "Unexpected generation kinds");
 743   // Skip two header words in the block content verification
 744   NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
 745   CMSCollector* collector = new CMSCollector(
 746     (ConcurrentMarkSweepGeneration*)_gens[1],
 747     _rem_set->as_CardTableRS(),
 748     (ConcurrentMarkSweepPolicy*) collector_policy());
 749 
 750   if (collector == NULL || !collector->completed_initialization()) {
 751     if (collector) {
 752       delete collector;  // Be nice in embedded situation
 753     }
 754     vm_shutdown_during_initialization("Could not create CMS collector");
 755     return false;
 756   }
 757   return true;  // success
 758 }
 759 
 760 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
 761   assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
 762 
 763   MutexLocker ml(Heap_lock);
 764   // Read the GC counts while holding the Heap_lock
 765   unsigned int full_gc_count_before = total_full_collections();
 766   unsigned int gc_count_before      = total_collections();
 767   {
 768     MutexUnlocker mu(Heap_lock);
 769     VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
 770     VMThread::execute(&op);
 771   }
 772 }
 773 #endif // INCLUDE_ALL_GCS
 774 
 775 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
 776    do_full_collection(clear_all_soft_refs, _n_gens - 1);
 777 }
 778 
 779 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 780                                           int max_level) {
 781   int local_max_level;
 782   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 783       gc_cause() == GCCause::_gc_locker) {
 784     local_max_level = 0;
 785   } else {
 786     local_max_level = max_level;
 787   }
 788 
 789   do_collection(true                 /* full */,
 790                 clear_all_soft_refs  /* clear_all_soft_refs */,
 791                 0                    /* size */,
 792                 false                /* is_tlab */,
 793                 local_max_level      /* max_level */);
 794   // Hack XXX FIX ME !!!
 795   // A scavenge may not have been attempted, or may have
 796   // been attempted and failed, because the old gen was too full
 797   if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
 798       incremental_collection_will_fail(false /* don't consult_young */)) {
 799     if (PrintGCDetails) {
 800       gclog_or_tty->print_cr("GC locker: Trying a full collection "
 801                              "because scavenge failed");
 802     }
 803     // This time allow the old gen to be collected as well
 804     do_collection(true                 /* full */,
 805                   clear_all_soft_refs  /* clear_all_soft_refs */,
 806                   0                    /* size */,
 807                   false                /* is_tlab */,
 808                   n_gens() - 1         /* max_level */);
 809   }
 810 }
 811 
 812 bool GenCollectedHeap::is_in_young(oop p) {
 813   bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
 814   assert(result == _gens[0]->is_in_reserved(p),
 815          err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, (void*)p));
 816   return result;
 817 }
 818 
 819 // Returns "TRUE" iff "p" points into the committed areas of the heap.
 820 bool GenCollectedHeap::is_in(const void* p) const {
 821   #ifndef ASSERT
 822   guarantee(VerifyBeforeGC      ||
 823             VerifyDuringGC      ||
 824             VerifyBeforeExit    ||
 825             VerifyDuringStartup ||
 826             PrintAssembly       ||
 827             tty->count() != 0   ||   // already printing
 828             VerifyAfterGC       ||
 829     VMError::fatal_error_in_progress(), "too expensive");
 830 
 831   #endif
 832   // This might be sped up with a cache of the last generation that
 833   // answered yes.
 834   for (int i = 0; i < _n_gens; i++) {
 835     if (_gens[i]->is_in(p)) return true;
 836   }
 837   // Otherwise...
 838   return false;
 839 }
 840 
 841 #ifdef ASSERT
 842 // Don't implement this by using is_in_young().  This method is used
 843 // in some cases to check that is_in_young() is correct.
 844 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
 845   assert(is_in_reserved(p) || p == NULL,
 846     "Does not work if address is non-null and outside of the heap");
 847   return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
 848 }
 849 #endif
 850 
 851 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
 852   for (int i = 0; i < _n_gens; i++) {
 853     _gens[i]->oop_iterate(cl);
 854   }
 855 }
 856 
 857 void GenCollectedHeap::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {
 858   for (int i = 0; i < _n_gens; i++) {
 859     _gens[i]->oop_iterate(mr, cl);
 860   }
 861 }
 862 
 863 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
 864   for (int i = 0; i < _n_gens; i++) {
 865     _gens[i]->object_iterate(cl);
 866   }
 867 }
 868 
 869 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
 870   for (int i = 0; i < _n_gens; i++) {
 871     _gens[i]->safe_object_iterate(cl);
 872   }
 873 }
 874 
 875 Space* GenCollectedHeap::space_containing(const void* addr) const {
 876   for (int i = 0; i < _n_gens; i++) {
 877     Space* res = _gens[i]->space_containing(addr);
 878     if (res != NULL) return res;
 879   }
 880   // Otherwise...
 881   assert(false, "Could not find containing space");
 882   return NULL;
 883 }
 884 
 885 
 886 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
 887   assert(is_in_reserved(addr), "block_start of address outside of heap");
 888   for (int i = 0; i < _n_gens; i++) {
 889     if (_gens[i]->is_in_reserved(addr)) {
 890       assert(_gens[i]->is_in(addr),
 891              "addr should be in allocated part of generation");
 892       return _gens[i]->block_start(addr);
 893     }
 894   }
 895   assert(false, "Some generation should contain the address");
 896   return NULL;
 897 }
 898 
 899 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
 900   assert(is_in_reserved(addr), "block_size of address outside of heap");
 901   for (int i = 0; i < _n_gens; i++) {
 902     if (_gens[i]->is_in_reserved(addr)) {
 903       assert(_gens[i]->is_in(addr),
 904              "addr should be in allocated part of generation");
 905       return _gens[i]->block_size(addr);
 906     }
 907   }
 908   assert(false, "Some generation should contain the address");
 909   return 0;
 910 }
 911 
 912 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
 913   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
 914   assert(block_start(addr) == addr, "addr must be a block start");
 915   for (int i = 0; i < _n_gens; i++) {
 916     if (_gens[i]->is_in_reserved(addr)) {
 917       return _gens[i]->block_is_obj(addr);
 918     }
 919   }
 920   assert(false, "Some generation should contain the address");
 921   return false;
 922 }
 923 
 924 bool GenCollectedHeap::supports_tlab_allocation() const {
 925   for (int i = 0; i < _n_gens; i += 1) {
 926     if (_gens[i]->supports_tlab_allocation()) {
 927       return true;
 928     }
 929   }
 930   return false;
 931 }
 932 
 933 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
 934   size_t result = 0;
 935   for (int i = 0; i < _n_gens; i += 1) {
 936     if (_gens[i]->supports_tlab_allocation()) {
 937       result += _gens[i]->tlab_capacity();
 938     }
 939   }
 940   return result;
 941 }
 942 
 943 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
 944   size_t result = 0;
 945   for (int i = 0; i < _n_gens; i += 1) {
 946     if (_gens[i]->supports_tlab_allocation()) {
 947       result += _gens[i]->unsafe_max_tlab_alloc();
 948     }
 949   }
 950   return result;
 951 }
 952 
 953 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
 954   bool gc_overhead_limit_was_exceeded;
 955   return collector_policy()->mem_allocate_work(size /* size */,
 956                                                true /* is_tlab */,
 957                                                &gc_overhead_limit_was_exceeded);
 958 }
 959 
 960 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
 961 // from the list headed by "*prev_ptr".
 962 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
 963   bool first = true;
 964   size_t min_size = 0;   // "first" makes this conceptually infinite.
 965   ScratchBlock **smallest_ptr, *smallest;
 966   ScratchBlock  *cur = *prev_ptr;
 967   while (cur) {
 968     assert(*prev_ptr == cur, "just checking");
 969     if (first || cur->num_words < min_size) {
 970       smallest_ptr = prev_ptr;
 971       smallest     = cur;
 972       min_size     = smallest->num_words;
 973       first        = false;
 974     }
 975     prev_ptr = &cur->next;
 976     cur     =  cur->next;
 977   }
 978   smallest      = *smallest_ptr;
 979   *smallest_ptr = smallest->next;
 980   return smallest;
 981 }
 982 
 983 // Sort the scratch block list headed by res into decreasing size order,
 984 // and set "res" to the result.
 985 static void sort_scratch_list(ScratchBlock*& list) {
 986   ScratchBlock* sorted = NULL;
 987   ScratchBlock* unsorted = list;
 988   while (unsorted) {
 989     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
 990     smallest->next  = sorted;
 991     sorted          = smallest;
 992   }
 993   list = sorted;
 994 }
 995 
 996 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
 997                                                size_t max_alloc_words) {
 998   ScratchBlock* res = NULL;
 999   for (int i = 0; i < _n_gens; i++) {
1000     _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1001   }
1002   sort_scratch_list(res);
1003   return res;
1004 }
1005 
1006 void GenCollectedHeap::release_scratch() {
1007   for (int i = 0; i < _n_gens; i++) {
1008     _gens[i]->reset_scratch();
1009   }
1010 }
1011 
1012 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1013   void do_generation(Generation* gen) {
1014     gen->prepare_for_verify();
1015   }
1016 };
1017 
1018 void GenCollectedHeap::prepare_for_verify() {
1019   ensure_parsability(false);        // no need to retire TLABs
1020   GenPrepareForVerifyClosure blk;
1021   generation_iterate(&blk, false);
1022 }
1023 
1024 
1025 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1026                                           bool old_to_young) {
1027   if (old_to_young) {
1028     for (int i = _n_gens-1; i >= 0; i--) {
1029       cl->do_generation(_gens[i]);
1030     }
1031   } else {
1032     for (int i = 0; i < _n_gens; i++) {
1033       cl->do_generation(_gens[i]);
1034     }
1035   }
1036 }
1037 
1038 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1039   for (int i = 0; i < _n_gens; i++) {
1040     _gens[i]->space_iterate(cl, true);
1041   }
1042 }
1043 
1044 bool GenCollectedHeap::is_maximal_no_gc() const {
1045   for (int i = 0; i < _n_gens; i++) {
1046     if (!_gens[i]->is_maximal_no_gc()) {
1047       return false;
1048     }
1049   }
1050   return true;
1051 }
1052 
1053 void GenCollectedHeap::save_marks() {
1054   for (int i = 0; i < _n_gens; i++) {
1055     _gens[i]->save_marks();
1056   }
1057 }
1058 
1059 void GenCollectedHeap::compute_new_generation_sizes(int collectedGen) {
1060   for (int i = 0; i <= collectedGen; i++) {
1061     _gens[i]->compute_new_size();
1062   }
1063 }
1064 
1065 GenCollectedHeap* GenCollectedHeap::heap() {
1066   assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1067   assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1068   return _gch;
1069 }
1070 
1071 
1072 void GenCollectedHeap::prepare_for_compaction() {
1073   guarantee(_n_gens = 2, "Wrong number of generations");
1074   Generation* old_gen = _gens[1];
1075   // Start by compacting into same gen.
1076   CompactPoint cp(old_gen, NULL, NULL);
1077   old_gen->prepare_for_compaction(&cp);
1078   Generation* young_gen = _gens[0];
1079   young_gen->prepare_for_compaction(&cp);
1080 }
1081 
1082 GCStats* GenCollectedHeap::gc_stats(int level) const {
1083   return _gens[level]->gc_stats();
1084 }
1085 
1086 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1087   for (int i = _n_gens-1; i >= 0; i--) {
1088     Generation* g = _gens[i];
1089     if (!silent) {
1090       gclog_or_tty->print(g->name());
1091       gclog_or_tty->print(" ");
1092     }
1093     g->verify();
1094   }
1095   if (!silent) {
1096     gclog_or_tty->print("remset ");
1097   }
1098   rem_set()->verify();
1099 }
1100 
1101 void GenCollectedHeap::print_on(outputStream* st) const {
1102   for (int i = 0; i < _n_gens; i++) {
1103     _gens[i]->print_on(st);
1104   }
1105   MetaspaceAux::print_on(st);
1106 }
1107 
1108 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1109   if (workers() != NULL) {
1110     workers()->threads_do(tc);
1111   }
1112 #if INCLUDE_ALL_GCS
1113   if (UseConcMarkSweepGC) {
1114     ConcurrentMarkSweepThread::threads_do(tc);
1115   }
1116 #endif // INCLUDE_ALL_GCS
1117 }
1118 
1119 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1120 #if INCLUDE_ALL_GCS
1121   if (UseParNewGC) {
1122     workers()->print_worker_threads_on(st);
1123   }
1124   if (UseConcMarkSweepGC) {
1125     ConcurrentMarkSweepThread::print_all_on(st);
1126   }
1127 #endif // INCLUDE_ALL_GCS
1128 }
1129 
1130 void GenCollectedHeap::print_on_error(outputStream* st) const {
1131   this->CollectedHeap::print_on_error(st);
1132 
1133 #if INCLUDE_ALL_GCS
1134   if (UseConcMarkSweepGC) {
1135     st->cr();
1136     CMSCollector::print_on_error(st);
1137   }
1138 #endif // INCLUDE_ALL_GCS
1139 }
1140 
1141 void GenCollectedHeap::print_tracing_info() const {
1142   if (TraceGen0Time) {
1143     get_gen(0)->print_summary_info();
1144   }
1145   if (TraceGen1Time) {
1146     get_gen(1)->print_summary_info();
1147   }
1148 }
1149 
1150 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1151   if (PrintGCDetails && Verbose) {
1152     gclog_or_tty->print(" "  SIZE_FORMAT
1153                         "->" SIZE_FORMAT
1154                         "("  SIZE_FORMAT ")",
1155                         prev_used, used(), capacity());
1156   } else {
1157     gclog_or_tty->print(" "  SIZE_FORMAT "K"
1158                         "->" SIZE_FORMAT "K"
1159                         "("  SIZE_FORMAT "K)",
1160                         prev_used / K, used() / K, capacity() / K);
1161   }
1162 }
1163 
1164 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1165  private:
1166   bool _full;
1167  public:
1168   void do_generation(Generation* gen) {
1169     gen->gc_prologue(_full);
1170   }
1171   GenGCPrologueClosure(bool full) : _full(full) {};
1172 };
1173 
1174 void GenCollectedHeap::gc_prologue(bool full) {
1175   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1176 
1177   always_do_update_barrier = false;
1178   // Fill TLAB's and such
1179   CollectedHeap::accumulate_statistics_all_tlabs();
1180   ensure_parsability(true);   // retire TLABs
1181 
1182   // Walk generations
1183   GenGCPrologueClosure blk(full);
1184   generation_iterate(&blk, false);  // not old-to-young.
1185 };
1186 
1187 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1188  private:
1189   bool _full;
1190  public:
1191   void do_generation(Generation* gen) {
1192     gen->gc_epilogue(_full);
1193   }
1194   GenGCEpilogueClosure(bool full) : _full(full) {};
1195 };
1196 
1197 void GenCollectedHeap::gc_epilogue(bool full) {
1198 #ifdef COMPILER2
1199   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1200   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1201   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1202 #endif /* COMPILER2 */
1203 
1204   resize_all_tlabs();
1205 
1206   GenGCEpilogueClosure blk(full);
1207   generation_iterate(&blk, false);  // not old-to-young.
1208 
1209   if (!CleanChunkPoolAsync) {
1210     Chunk::clean_chunk_pool();
1211   }
1212 
1213   MetaspaceCounters::update_performance_counters();
1214   CompressedClassSpaceCounters::update_performance_counters();
1215 
1216   always_do_update_barrier = UseConcMarkSweepGC;
1217 };
1218 
1219 #ifndef PRODUCT
1220 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1221  private:
1222  public:
1223   void do_generation(Generation* gen) {
1224     gen->record_spaces_top();
1225   }
1226 };
1227 
1228 void GenCollectedHeap::record_gen_tops_before_GC() {
1229   if (ZapUnusedHeapArea) {
1230     GenGCSaveTopsBeforeGCClosure blk;
1231     generation_iterate(&blk, false);  // not old-to-young.
1232   }
1233 }
1234 #endif  // not PRODUCT
1235 
1236 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1237  public:
1238   void do_generation(Generation* gen) {
1239     gen->ensure_parsability();
1240   }
1241 };
1242 
1243 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1244   CollectedHeap::ensure_parsability(retire_tlabs);
1245   GenEnsureParsabilityClosure ep_cl;
1246   generation_iterate(&ep_cl, false);
1247 }
1248 
1249 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1250                                               oop obj,
1251                                               size_t obj_size) {
1252   guarantee(old_gen->level() == 1, "We only get here with an old generation");
1253   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1254   HeapWord* result = NULL;
1255 
1256   result = old_gen->expand_and_allocate(obj_size, false);
1257 
1258   if (result != NULL) {
1259     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1260   }
1261   return oop(result);
1262 }
1263 
1264 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1265   jlong _time;   // in ms
1266   jlong _now;    // in ms
1267 
1268  public:
1269   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1270 
1271   jlong time() { return _time; }
1272 
1273   void do_generation(Generation* gen) {
1274     _time = MIN2(_time, gen->time_of_last_gc(_now));
1275   }
1276 };
1277 
1278 jlong GenCollectedHeap::millis_since_last_gc() {
1279   // We need a monotonically non-deccreasing time in ms but
1280   // os::javaTimeMillis() does not guarantee monotonicity.
1281   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1282   GenTimeOfLastGCClosure tolgc_cl(now);
1283   // iterate over generations getting the oldest
1284   // time that a generation was collected
1285   generation_iterate(&tolgc_cl, false);
1286 
1287   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1288   // provided the underlying platform provides such a time source
1289   // (and it is bug free). So we still have to guard against getting
1290   // back a time later than 'now'.
1291   jlong retVal = now - tolgc_cl.time();
1292   if (retVal < 0) {
1293     NOT_PRODUCT(warning("time warp: "INT64_FORMAT, retVal);)
1294     return 0;
1295   }
1296   return retVal;
1297 }