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     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
 388     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 389     // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 390     // so we can assume here that the next GC id is what we want.
 391     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
 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         // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 425         // so we can assume here that the next GC id is what we want.
 426         GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
 427         TraceCollectorStats tcs(_gens[i]->counters());
 428         TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
 429 
 430         size_t prev_used = _gens[i]->used();
 431         _gens[i]->stat_record()->invocations++;
 432         _gens[i]->stat_record()->accumulated_time.start();
 433 
 434         // Must be done anew before each collection because
 435         // a previous collection will do mangling and will
 436         // change top of some spaces.
 437         record_gen_tops_before_GC();
 438 
 439         if (PrintGC && Verbose) {
 440           gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
 441                      i,
 442                      _gens[i]->stat_record()->invocations,
 443                      size*HeapWordSize);
 444         }
 445 
 446         if (VerifyBeforeGC && i >= VerifyGCLevel &&
 447             total_collections() >= VerifyGCStartAt) {
 448           HandleMark hm;  // Discard invalid handles created during verification
 449           if (!prepared_for_verification) {
 450             prepare_for_verify();
 451             prepared_for_verification = true;
 452           }
 453           Universe::verify(" VerifyBeforeGC:");
 454         }
 455         COMPILER2_PRESENT(DerivedPointerTable::clear());
 456 
 457         if (!must_restore_marks_for_biased_locking &&
 458             _gens[i]->performs_in_place_marking()) {
 459           // We perform this mark word preservation work lazily
 460           // because it's only at this point that we know whether we
 461           // absolutely have to do it; we want to avoid doing it for
 462           // scavenge-only collections where it's unnecessary
 463           must_restore_marks_for_biased_locking = true;
 464           BiasedLocking::preserve_marks();
 465         }
 466 
 467         // Do collection work
 468         {
 469           // Note on ref discovery: For what appear to be historical reasons,
 470           // GCH enables and disabled (by enqueing) refs discovery.
 471           // In the future this should be moved into the generation's
 472           // collect method so that ref discovery and enqueueing concerns
 473           // are local to a generation. The collect method could return
 474           // an appropriate indication in the case that notification on
 475           // the ref lock was needed. This will make the treatment of
 476           // weak refs more uniform (and indeed remove such concerns
 477           // from GCH). XXX
 478 
 479           HandleMark hm;  // Discard invalid handles created during gc
 480           save_marks();   // save marks for all gens
 481           // We want to discover references, but not process them yet.
 482           // This mode is disabled in process_discovered_references if the
 483           // generation does some collection work, or in
 484           // enqueue_discovered_references if the generation returns
 485           // without doing any work.
 486           ReferenceProcessor* rp = _gens[i]->ref_processor();
 487           // If the discovery of ("weak") refs in this generation is
 488           // atomic wrt other collectors in this configuration, we
 489           // are guaranteed to have empty discovered ref lists.
 490           if (rp->discovery_is_atomic()) {
 491             rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
 492             rp->setup_policy(do_clear_all_soft_refs);
 493           } else {
 494             // collect() below will enable discovery as appropriate
 495           }
 496           _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
 497           if (!rp->enqueuing_is_done()) {
 498             rp->enqueue_discovered_references();
 499           } else {
 500             rp->set_enqueuing_is_done(false);
 501           }
 502           rp->verify_no_references_recorded();
 503         }
 504         max_level_collected = i;
 505 
 506         // Determine if allocation request was met.
 507         if (size > 0) {
 508           if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
 509             if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
 510               size = 0;
 511             }
 512           }
 513         }
 514 
 515         COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 516 
 517         _gens[i]->stat_record()->accumulated_time.stop();
 518 
 519         update_gc_stats(i, full);
 520 
 521         if (VerifyAfterGC && i >= VerifyGCLevel &&
 522             total_collections() >= VerifyGCStartAt) {
 523           HandleMark hm;  // Discard invalid handles created during verification
 524           Universe::verify(" VerifyAfterGC:");
 525         }
 526 
 527         if (PrintGCDetails) {
 528           gclog_or_tty->print(":");
 529           _gens[i]->print_heap_change(prev_used);
 530         }
 531       }
 532     }
 533 
 534     // Update "complete" boolean wrt what actually transpired --
 535     // for instance, a promotion failure could have led to
 536     // a whole heap collection.
 537     complete = complete || (max_level_collected == n_gens() - 1);
 538 
 539     if (complete) { // We did a "major" collection
 540       // FIXME: See comment at pre_full_gc_dump call
 541       post_full_gc_dump(NULL);   // do any post full gc dumps
 542     }
 543 
 544     if (PrintGCDetails) {
 545       print_heap_change(gch_prev_used);
 546 
 547       // Print metaspace info for full GC with PrintGCDetails flag.
 548       if (complete) {
 549         MetaspaceAux::print_metaspace_change(metadata_prev_used);
 550       }
 551     }
 552 
 553     for (int j = max_level_collected; j >= 0; j -= 1) {
 554       // Adjust generation sizes.
 555       _gens[j]->compute_new_size();
 556     }
 557 
 558     if (complete) {
 559       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 560       ClassLoaderDataGraph::purge();
 561       MetaspaceAux::verify_metrics();
 562       // Resize the metaspace capacity after full collections
 563       MetaspaceGC::compute_new_size();
 564       update_full_collections_completed();
 565     }
 566 
 567     // Track memory usage and detect low memory after GC finishes
 568     MemoryService::track_memory_usage();
 569 
 570     gc_epilogue(complete);
 571 
 572     if (must_restore_marks_for_biased_locking) {
 573       BiasedLocking::restore_marks();
 574     }
 575   }
 576 
 577   AdaptiveSizePolicy* sp = gen_policy()->size_policy();
 578   AdaptiveSizePolicyOutput(sp, total_collections());
 579 
 580   print_heap_after_gc();
 581 
 582 #ifdef TRACESPINNING
 583   ParallelTaskTerminator::print_termination_counts();
 584 #endif
 585 }
 586 
 587 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 588   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 589 }
 590 
 591 void GenCollectedHeap::set_par_threads(uint t) {
 592   SharedHeap::set_par_threads(t);
 593   _gen_process_roots_tasks->set_n_threads(t);
 594 }
 595 
 596 void GenCollectedHeap::
 597 gen_process_roots(int level,
 598                   bool younger_gens_as_roots,
 599                   bool activate_scope,
 600                   SharedHeap::ScanningOption so,
 601                   OopsInGenClosure* not_older_gens,
 602                   OopsInGenClosure* weak_roots,
 603                   OopsInGenClosure* older_gens,
 604                   CLDClosure* cld_closure,
 605                   CLDClosure* weak_cld_closure,
 606                   CodeBlobClosure* code_closure) {
 607 
 608   // General roots.
 609   SharedHeap::process_roots(activate_scope, so,
 610                             not_older_gens, weak_roots,
 611                             cld_closure, weak_cld_closure,
 612                             code_closure);
 613 
 614   if (younger_gens_as_roots) {
 615     if (!_gen_process_roots_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 616       for (int i = 0; i < level; i++) {
 617         not_older_gens->set_generation(_gens[i]);
 618         _gens[i]->oop_iterate(not_older_gens);
 619       }
 620       not_older_gens->reset_generation();
 621     }
 622   }
 623   // When collection is parallel, all threads get to cooperate to do
 624   // older-gen scanning.
 625   for (int i = level+1; i < _n_gens; i++) {
 626     older_gens->set_generation(_gens[i]);
 627     rem_set()->younger_refs_iterate(_gens[i], older_gens);
 628     older_gens->reset_generation();
 629   }
 630 
 631   _gen_process_roots_tasks->all_tasks_completed();
 632 }
 633 
 634 void GenCollectedHeap::
 635 gen_process_roots(int level,
 636                   bool younger_gens_as_roots,
 637                   bool activate_scope,
 638                   SharedHeap::ScanningOption so,
 639                   bool only_strong_roots,
 640                   OopsInGenClosure* not_older_gens,
 641                   OopsInGenClosure* older_gens,
 642                   CLDClosure* cld_closure) {
 643 
 644   const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
 645 
 646   bool is_moving_collection = false;
 647   if (level == 0 || is_adjust_phase) {
 648     // young collections are always moving
 649     is_moving_collection = true;
 650   }
 651 
 652   MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
 653   CodeBlobClosure* code_closure = &mark_code_closure;
 654 
 655   gen_process_roots(level,
 656                     younger_gens_as_roots,
 657                     activate_scope, so,
 658                     not_older_gens, only_strong_roots ? NULL : not_older_gens,
 659                     older_gens,
 660                     cld_closure, only_strong_roots ? NULL : cld_closure,
 661                     code_closure);
 662 
 663 }
 664 
 665 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
 666   SharedHeap::process_weak_roots(root_closure);
 667   // "Local" "weak" refs
 668   for (int i = 0; i < _n_gens; i++) {
 669     _gens[i]->ref_processor()->weak_oops_do(root_closure);
 670   }
 671 }
 672 
 673 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 674 void GenCollectedHeap::                                                 \
 675 oop_since_save_marks_iterate(int level,                                 \
 676                              OopClosureType* cur,                       \
 677                              OopClosureType* older) {                   \
 678   _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur);           \
 679   for (int i = level+1; i < n_gens(); i++) {                            \
 680     _gens[i]->oop_since_save_marks_iterate##nv_suffix(older);           \
 681   }                                                                     \
 682 }
 683 
 684 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 685 
 686 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 687 
 688 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
 689   for (int i = level; i < _n_gens; i++) {
 690     if (!_gens[i]->no_allocs_since_save_marks()) return false;
 691   }
 692   return true;
 693 }
 694 
 695 bool GenCollectedHeap::supports_inline_contig_alloc() const {
 696   return _gens[0]->supports_inline_contig_alloc();
 697 }
 698 
 699 HeapWord** GenCollectedHeap::top_addr() const {
 700   return _gens[0]->top_addr();
 701 }
 702 
 703 HeapWord** GenCollectedHeap::end_addr() const {
 704   return _gens[0]->end_addr();
 705 }
 706 
 707 // public collection interfaces
 708 
 709 void GenCollectedHeap::collect(GCCause::Cause cause) {
 710   if (should_do_concurrent_full_gc(cause)) {
 711 #if INCLUDE_ALL_GCS
 712     // mostly concurrent full collection
 713     collect_mostly_concurrent(cause);
 714 #else  // INCLUDE_ALL_GCS
 715     ShouldNotReachHere();
 716 #endif // INCLUDE_ALL_GCS
 717   } else if (cause == GCCause::_wb_young_gc) {
 718     // minor collection for WhiteBox API
 719     collect(cause, 0);
 720   } else {
 721 #ifdef ASSERT
 722   if (cause == GCCause::_scavenge_alot) {
 723     // minor collection only
 724     collect(cause, 0);
 725   } else {
 726     // Stop-the-world full collection
 727     collect(cause, n_gens() - 1);
 728   }
 729 #else
 730     // Stop-the-world full collection
 731     collect(cause, n_gens() - 1);
 732 #endif
 733   }
 734 }
 735 
 736 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
 737   // The caller doesn't have the Heap_lock
 738   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 739   MutexLocker ml(Heap_lock);
 740   collect_locked(cause, max_level);
 741 }
 742 
 743 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
 744   // The caller has the Heap_lock
 745   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
 746   collect_locked(cause, n_gens() - 1);
 747 }
 748 
 749 // this is the private collection interface
 750 // The Heap_lock is expected to be held on entry.
 751 
 752 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
 753   // Read the GC count while holding the Heap_lock
 754   unsigned int gc_count_before      = total_collections();
 755   unsigned int full_gc_count_before = total_full_collections();
 756   {
 757     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
 758     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
 759                          cause, max_level);
 760     VMThread::execute(&op);
 761   }
 762 }
 763 
 764 #if INCLUDE_ALL_GCS
 765 bool GenCollectedHeap::create_cms_collector() {
 766 
 767   assert(((_gens[1]->kind() == Generation::ConcurrentMarkSweep) ||
 768          (_gens[1]->kind() == Generation::ASConcurrentMarkSweep)),
 769          "Unexpected generation kinds");
 770   // Skip two header words in the block content verification
 771   NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
 772   CMSCollector* collector = new CMSCollector(
 773     (ConcurrentMarkSweepGeneration*)_gens[1],
 774     _rem_set->as_CardTableRS(),
 775     (ConcurrentMarkSweepPolicy*) collector_policy());
 776 
 777   if (collector == NULL || !collector->completed_initialization()) {
 778     if (collector) {
 779       delete collector;  // Be nice in embedded situation
 780     }
 781     vm_shutdown_during_initialization("Could not create CMS collector");
 782     return false;
 783   }
 784   return true;  // success
 785 }
 786 
 787 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
 788   assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
 789 
 790   MutexLocker ml(Heap_lock);
 791   // Read the GC counts while holding the Heap_lock
 792   unsigned int full_gc_count_before = total_full_collections();
 793   unsigned int gc_count_before      = total_collections();
 794   {
 795     MutexUnlocker mu(Heap_lock);
 796     VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
 797     VMThread::execute(&op);
 798   }
 799 }
 800 #endif // INCLUDE_ALL_GCS
 801 
 802 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
 803    do_full_collection(clear_all_soft_refs, _n_gens - 1);
 804 }
 805 
 806 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 807                                           int max_level) {
 808   int local_max_level;
 809   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 810       gc_cause() == GCCause::_gc_locker) {
 811     local_max_level = 0;
 812   } else {
 813     local_max_level = max_level;
 814   }
 815 
 816   do_collection(true                 /* full */,
 817                 clear_all_soft_refs  /* clear_all_soft_refs */,
 818                 0                    /* size */,
 819                 false                /* is_tlab */,
 820                 local_max_level      /* max_level */);
 821   // Hack XXX FIX ME !!!
 822   // A scavenge may not have been attempted, or may have
 823   // been attempted and failed, because the old gen was too full
 824   if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
 825       incremental_collection_will_fail(false /* don't consult_young */)) {
 826     if (PrintGCDetails) {
 827       gclog_or_tty->print_cr("GC locker: Trying a full collection "
 828                              "because scavenge failed");
 829     }
 830     // This time allow the old gen to be collected as well
 831     do_collection(true                 /* full */,
 832                   clear_all_soft_refs  /* clear_all_soft_refs */,
 833                   0                    /* size */,
 834                   false                /* is_tlab */,
 835                   n_gens() - 1         /* max_level */);
 836   }
 837 }
 838 
 839 bool GenCollectedHeap::is_in_young(oop p) {
 840   bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
 841   assert(result == _gens[0]->is_in_reserved(p),
 842          err_msg("incorrect test - result=%d, p=" PTR_FORMAT, result, p2i((void*)p)));
 843   return result;
 844 }
 845 
 846 // Returns "TRUE" iff "p" points into the committed areas of the heap.
 847 bool GenCollectedHeap::is_in(const void* p) const {
 848   #ifndef ASSERT
 849   guarantee(VerifyBeforeGC      ||
 850             VerifyDuringGC      ||
 851             VerifyBeforeExit    ||
 852             VerifyDuringStartup ||
 853             PrintAssembly       ||
 854             tty->count() != 0   ||   // already printing
 855             VerifyAfterGC       ||
 856     VMError::fatal_error_in_progress(), "too expensive");
 857 
 858   #endif
 859   // This might be sped up with a cache of the last generation that
 860   // answered yes.
 861   for (int i = 0; i < _n_gens; i++) {
 862     if (_gens[i]->is_in(p)) return true;
 863   }
 864   // Otherwise...
 865   return false;
 866 }
 867 
 868 #ifdef ASSERT
 869 // Don't implement this by using is_in_young().  This method is used
 870 // in some cases to check that is_in_young() is correct.
 871 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
 872   assert(is_in_reserved(p) || p == NULL,
 873     "Does not work if address is non-null and outside of the heap");
 874   return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
 875 }
 876 #endif
 877 
 878 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
 879   for (int i = 0; i < _n_gens; i++) {
 880     _gens[i]->oop_iterate(cl);
 881   }
 882 }
 883 
 884 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
 885   for (int i = 0; i < _n_gens; i++) {
 886     _gens[i]->object_iterate(cl);
 887   }
 888 }
 889 
 890 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
 891   for (int i = 0; i < _n_gens; i++) {
 892     _gens[i]->safe_object_iterate(cl);
 893   }
 894 }
 895 
 896 Space* GenCollectedHeap::space_containing(const void* addr) const {
 897   for (int i = 0; i < _n_gens; i++) {
 898     Space* res = _gens[i]->space_containing(addr);
 899     if (res != NULL) return res;
 900   }
 901   // Otherwise...
 902   assert(false, "Could not find containing space");
 903   return NULL;
 904 }
 905 
 906 
 907 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
 908   assert(is_in_reserved(addr), "block_start of address outside of heap");
 909   for (int i = 0; i < _n_gens; i++) {
 910     if (_gens[i]->is_in_reserved(addr)) {
 911       assert(_gens[i]->is_in(addr),
 912              "addr should be in allocated part of generation");
 913       return _gens[i]->block_start(addr);
 914     }
 915   }
 916   assert(false, "Some generation should contain the address");
 917   return NULL;
 918 }
 919 
 920 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
 921   assert(is_in_reserved(addr), "block_size of address outside of heap");
 922   for (int i = 0; i < _n_gens; i++) {
 923     if (_gens[i]->is_in_reserved(addr)) {
 924       assert(_gens[i]->is_in(addr),
 925              "addr should be in allocated part of generation");
 926       return _gens[i]->block_size(addr);
 927     }
 928   }
 929   assert(false, "Some generation should contain the address");
 930   return 0;
 931 }
 932 
 933 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
 934   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
 935   assert(block_start(addr) == addr, "addr must be a block start");
 936   for (int i = 0; i < _n_gens; i++) {
 937     if (_gens[i]->is_in_reserved(addr)) {
 938       return _gens[i]->block_is_obj(addr);
 939     }
 940   }
 941   assert(false, "Some generation should contain the address");
 942   return false;
 943 }
 944 
 945 bool GenCollectedHeap::supports_tlab_allocation() const {
 946   for (int i = 0; i < _n_gens; i += 1) {
 947     if (_gens[i]->supports_tlab_allocation()) {
 948       return true;
 949     }
 950   }
 951   return false;
 952 }
 953 
 954 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
 955   size_t result = 0;
 956   for (int i = 0; i < _n_gens; i += 1) {
 957     if (_gens[i]->supports_tlab_allocation()) {
 958       result += _gens[i]->tlab_capacity();
 959     }
 960   }
 961   return result;
 962 }
 963 
 964 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
 965   size_t result = 0;
 966   for (int i = 0; i < _n_gens; i += 1) {
 967     if (_gens[i]->supports_tlab_allocation()) {
 968       result += _gens[i]->tlab_used();
 969     }
 970   }
 971   return result;
 972 }
 973 
 974 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
 975   size_t result = 0;
 976   for (int i = 0; i < _n_gens; i += 1) {
 977     if (_gens[i]->supports_tlab_allocation()) {
 978       result += _gens[i]->unsafe_max_tlab_alloc();
 979     }
 980   }
 981   return result;
 982 }
 983 
 984 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
 985   bool gc_overhead_limit_was_exceeded;
 986   return collector_policy()->mem_allocate_work(size /* size */,
 987                                                true /* is_tlab */,
 988                                                &gc_overhead_limit_was_exceeded);
 989 }
 990 
 991 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
 992 // from the list headed by "*prev_ptr".
 993 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
 994   bool first = true;
 995   size_t min_size = 0;   // "first" makes this conceptually infinite.
 996   ScratchBlock **smallest_ptr, *smallest;
 997   ScratchBlock  *cur = *prev_ptr;
 998   while (cur) {
 999     assert(*prev_ptr == cur, "just checking");
1000     if (first || cur->num_words < min_size) {
1001       smallest_ptr = prev_ptr;
1002       smallest     = cur;
1003       min_size     = smallest->num_words;
1004       first        = false;
1005     }
1006     prev_ptr = &cur->next;
1007     cur     =  cur->next;
1008   }
1009   smallest      = *smallest_ptr;
1010   *smallest_ptr = smallest->next;
1011   return smallest;
1012 }
1013 
1014 // Sort the scratch block list headed by res into decreasing size order,
1015 // and set "res" to the result.
1016 static void sort_scratch_list(ScratchBlock*& list) {
1017   ScratchBlock* sorted = NULL;
1018   ScratchBlock* unsorted = list;
1019   while (unsorted) {
1020     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1021     smallest->next  = sorted;
1022     sorted          = smallest;
1023   }
1024   list = sorted;
1025 }
1026 
1027 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1028                                                size_t max_alloc_words) {
1029   ScratchBlock* res = NULL;
1030   for (int i = 0; i < _n_gens; i++) {
1031     _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1032   }
1033   sort_scratch_list(res);
1034   return res;
1035 }
1036 
1037 void GenCollectedHeap::release_scratch() {
1038   for (int i = 0; i < _n_gens; i++) {
1039     _gens[i]->reset_scratch();
1040   }
1041 }
1042 
1043 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1044   void do_generation(Generation* gen) {
1045     gen->prepare_for_verify();
1046   }
1047 };
1048 
1049 void GenCollectedHeap::prepare_for_verify() {
1050   ensure_parsability(false);        // no need to retire TLABs
1051   GenPrepareForVerifyClosure blk;
1052   generation_iterate(&blk, false);
1053 }
1054 
1055 
1056 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1057                                           bool old_to_young) {
1058   if (old_to_young) {
1059     for (int i = _n_gens-1; i >= 0; i--) {
1060       cl->do_generation(_gens[i]);
1061     }
1062   } else {
1063     for (int i = 0; i < _n_gens; i++) {
1064       cl->do_generation(_gens[i]);
1065     }
1066   }
1067 }
1068 
1069 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1070   for (int i = 0; i < _n_gens; i++) {
1071     _gens[i]->space_iterate(cl, true);
1072   }
1073 }
1074 
1075 bool GenCollectedHeap::is_maximal_no_gc() const {
1076   for (int i = 0; i < _n_gens; i++) {
1077     if (!_gens[i]->is_maximal_no_gc()) {
1078       return false;
1079     }
1080   }
1081   return true;
1082 }
1083 
1084 void GenCollectedHeap::save_marks() {
1085   for (int i = 0; i < _n_gens; i++) {
1086     _gens[i]->save_marks();
1087   }
1088 }
1089 
1090 GenCollectedHeap* GenCollectedHeap::heap() {
1091   assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1092   assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1093   return _gch;
1094 }
1095 
1096 
1097 void GenCollectedHeap::prepare_for_compaction() {
1098   guarantee(_n_gens = 2, "Wrong number of generations");
1099   Generation* old_gen = _gens[1];
1100   // Start by compacting into same gen.
1101   CompactPoint cp(old_gen);
1102   old_gen->prepare_for_compaction(&cp);
1103   Generation* young_gen = _gens[0];
1104   young_gen->prepare_for_compaction(&cp);
1105 }
1106 
1107 GCStats* GenCollectedHeap::gc_stats(int level) const {
1108   return _gens[level]->gc_stats();
1109 }
1110 
1111 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1112   for (int i = _n_gens-1; i >= 0; i--) {
1113     Generation* g = _gens[i];
1114     if (!silent) {
1115       gclog_or_tty->print("%s", g->name());
1116       gclog_or_tty->print(" ");
1117     }
1118     g->verify();
1119   }
1120   if (!silent) {
1121     gclog_or_tty->print("remset ");
1122   }
1123   rem_set()->verify();
1124 }
1125 
1126 void GenCollectedHeap::print_on(outputStream* st) const {
1127   for (int i = 0; i < _n_gens; i++) {
1128     _gens[i]->print_on(st);
1129   }
1130   MetaspaceAux::print_on(st);
1131 }
1132 
1133 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1134   if (workers() != NULL) {
1135     workers()->threads_do(tc);
1136   }
1137 #if INCLUDE_ALL_GCS
1138   if (UseConcMarkSweepGC) {
1139     ConcurrentMarkSweepThread::threads_do(tc);
1140   }
1141 #endif // INCLUDE_ALL_GCS
1142 }
1143 
1144 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1145 #if INCLUDE_ALL_GCS
1146   if (UseParNewGC) {
1147     workers()->print_worker_threads_on(st);
1148   }
1149   if (UseConcMarkSweepGC) {
1150     ConcurrentMarkSweepThread::print_all_on(st);
1151   }
1152 #endif // INCLUDE_ALL_GCS
1153 }
1154 
1155 void GenCollectedHeap::print_on_error(outputStream* st) const {
1156   this->CollectedHeap::print_on_error(st);
1157 
1158 #if INCLUDE_ALL_GCS
1159   if (UseConcMarkSweepGC) {
1160     st->cr();
1161     CMSCollector::print_on_error(st);
1162   }
1163 #endif // INCLUDE_ALL_GCS
1164 }
1165 
1166 void GenCollectedHeap::print_tracing_info() const {
1167   if (TraceGen0Time) {
1168     get_gen(0)->print_summary_info();
1169   }
1170   if (TraceGen1Time) {
1171     get_gen(1)->print_summary_info();
1172   }
1173 }
1174 
1175 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1176   if (PrintGCDetails && Verbose) {
1177     gclog_or_tty->print(" "  SIZE_FORMAT
1178                         "->" SIZE_FORMAT
1179                         "("  SIZE_FORMAT ")",
1180                         prev_used, used(), capacity());
1181   } else {
1182     gclog_or_tty->print(" "  SIZE_FORMAT "K"
1183                         "->" SIZE_FORMAT "K"
1184                         "("  SIZE_FORMAT "K)",
1185                         prev_used / K, used() / K, capacity() / K);
1186   }
1187 }
1188 
1189 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1190  private:
1191   bool _full;
1192  public:
1193   void do_generation(Generation* gen) {
1194     gen->gc_prologue(_full);
1195   }
1196   GenGCPrologueClosure(bool full) : _full(full) {};
1197 };
1198 
1199 void GenCollectedHeap::gc_prologue(bool full) {
1200   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1201 
1202   always_do_update_barrier = false;
1203   // Fill TLAB's and such
1204   CollectedHeap::accumulate_statistics_all_tlabs();
1205   ensure_parsability(true);   // retire TLABs
1206 
1207   // Walk generations
1208   GenGCPrologueClosure blk(full);
1209   generation_iterate(&blk, false);  // not old-to-young.
1210 };
1211 
1212 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1213  private:
1214   bool _full;
1215  public:
1216   void do_generation(Generation* gen) {
1217     gen->gc_epilogue(_full);
1218   }
1219   GenGCEpilogueClosure(bool full) : _full(full) {};
1220 };
1221 
1222 void GenCollectedHeap::gc_epilogue(bool full) {
1223 #ifdef COMPILER2
1224   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1225   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1226   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1227 #endif /* COMPILER2 */
1228 
1229   resize_all_tlabs();
1230 
1231   GenGCEpilogueClosure blk(full);
1232   generation_iterate(&blk, false);  // not old-to-young.
1233 
1234   if (!CleanChunkPoolAsync) {
1235     Chunk::clean_chunk_pool();
1236   }
1237 
1238   MetaspaceCounters::update_performance_counters();
1239   CompressedClassSpaceCounters::update_performance_counters();
1240 
1241   always_do_update_barrier = UseConcMarkSweepGC;
1242 };
1243 
1244 #ifndef PRODUCT
1245 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1246  private:
1247  public:
1248   void do_generation(Generation* gen) {
1249     gen->record_spaces_top();
1250   }
1251 };
1252 
1253 void GenCollectedHeap::record_gen_tops_before_GC() {
1254   if (ZapUnusedHeapArea) {
1255     GenGCSaveTopsBeforeGCClosure blk;
1256     generation_iterate(&blk, false);  // not old-to-young.
1257   }
1258 }
1259 #endif  // not PRODUCT
1260 
1261 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1262  public:
1263   void do_generation(Generation* gen) {
1264     gen->ensure_parsability();
1265   }
1266 };
1267 
1268 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1269   CollectedHeap::ensure_parsability(retire_tlabs);
1270   GenEnsureParsabilityClosure ep_cl;
1271   generation_iterate(&ep_cl, false);
1272 }
1273 
1274 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1275                                               oop obj,
1276                                               size_t obj_size) {
1277   guarantee(old_gen->level() == 1, "We only get here with an old generation");
1278   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1279   HeapWord* result = NULL;
1280 
1281   result = old_gen->expand_and_allocate(obj_size, false);
1282 
1283   if (result != NULL) {
1284     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1285   }
1286   return oop(result);
1287 }
1288 
1289 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1290   jlong _time;   // in ms
1291   jlong _now;    // in ms
1292 
1293  public:
1294   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1295 
1296   jlong time() { return _time; }
1297 
1298   void do_generation(Generation* gen) {
1299     _time = MIN2(_time, gen->time_of_last_gc(_now));
1300   }
1301 };
1302 
1303 jlong GenCollectedHeap::millis_since_last_gc() {
1304   // We need a monotonically non-deccreasing time in ms but
1305   // os::javaTimeMillis() does not guarantee monotonicity.
1306   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1307   GenTimeOfLastGCClosure tolgc_cl(now);
1308   // iterate over generations getting the oldest
1309   // time that a generation was collected
1310   generation_iterate(&tolgc_cl, false);
1311 
1312   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1313   // provided the underlying platform provides such a time source
1314   // (and it is bug free). So we still have to guard against getting
1315   // back a time later than 'now'.
1316   jlong retVal = now - tolgc_cl.time();
1317   if (retVal < 0) {
1318     NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1319     return 0;
1320   }
1321   return retVal;
1322 }