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 something is 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   GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
 202   guarantee(policy->is_generation_policy(), "Illegal policy type");
 203   DefNewGeneration* def_new_gen = (DefNewGeneration*) get_gen(0);
 204   assert(def_new_gen->kind() == Generation::DefNew ||
 205          def_new_gen->kind() == Generation::ParNew,
 206          "Wrong generation kind");
 207 
 208   Generation* old_gen = get_gen(1);
 209   assert(old_gen->kind() == Generation::ConcurrentMarkSweep ||
 210          old_gen->kind() == Generation::MarkSweepCompact,
 211     "Wrong generation kind");
 212 
 213   policy->initialize_size_policy(def_new_gen->eden()->capacity(),
 214                                  old_gen->capacity(),
 215                                  def_new_gen->from()->capacity());
 216   policy->initialize_gc_policy_counters();
 217 }
 218 
 219 void GenCollectedHeap::ref_processing_init() {
 220   SharedHeap::ref_processing_init();
 221   for (int i = 0; i < _n_gens; i++) {
 222     _gens[i]->ref_processor_init();
 223   }
 224 }
 225 
 226 size_t GenCollectedHeap::capacity() const {
 227   size_t res = 0;
 228   for (int i = 0; i < _n_gens; i++) {
 229     res += _gens[i]->capacity();
 230   }
 231   return res;
 232 }
 233 
 234 size_t GenCollectedHeap::used() const {
 235   size_t res = 0;
 236   for (int i = 0; i < _n_gens; i++) {
 237     res += _gens[i]->used();
 238   }
 239   return res;
 240 }
 241 
 242 // Save the "used_region" for generations level and lower.
 243 void GenCollectedHeap::save_used_regions(int level) {
 244   assert(level < _n_gens, "Illegal level parameter");
 245   for (int i = level; i >= 0; i--) {
 246     _gens[i]->save_used_region();
 247   }

 248 }
 249 
 250 size_t GenCollectedHeap::max_capacity() const {
 251   size_t res = 0;
 252   for (int i = 0; i < _n_gens; i++) {
 253     res += _gens[i]->max_capacity();
 254   }
 255   return res;
 256 }
 257 
 258 // Update the _full_collections_completed counter
 259 // at the end of a stop-world full GC.
 260 unsigned int GenCollectedHeap::update_full_collections_completed() {
 261   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 262   assert(_full_collections_completed <= _total_full_collections,
 263          "Can't complete more collections than were started");
 264   _full_collections_completed = _total_full_collections;
 265   ml.notify_all();
 266   return _full_collections_completed;
 267 }
 268 
 269 // Update the _full_collections_completed counter, as appropriate,
 270 // at the end of a concurrent GC cycle. Note the conditional update
 271 // below to allow this method to be called by a concurrent collector
 272 // without synchronizing in any manner with the VM thread (which
 273 // may already have initiated a STW full collection "concurrently").
 274 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
 275   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 276   assert((_full_collections_completed <= _total_full_collections) &&
 277          (count <= _total_full_collections),
 278          "Can't complete more collections than were started");
 279   if (count > _full_collections_completed) {
 280     _full_collections_completed = count;
 281     ml.notify_all();
 282   }
 283   return _full_collections_completed;
 284 }
 285 
 286 
 287 #ifndef PRODUCT
 288 // Override of memory state checking method in CollectedHeap:
 289 // Some collectors (CMS for example) can't have badHeapWordVal written
 290 // in the first two words of an object. (For instance , in the case of
 291 // CMS these words hold state used to synchronize between certain
 292 // (concurrent) GC steps and direct allocating mutators.)
 293 // The skip_header_HeapWords() method below, allows us to skip
 294 // over the requisite number of HeapWord's. Note that (for
 295 // generational collectors) this means that those many words are
 296 // skipped in each object, irrespective of the generation in which
 297 // that object lives. The resultant loss of precision seems to be
 298 // harmless and the pain of avoiding that imprecision appears somewhat
 299 // higher than we are prepared to pay for such rudimentary debugging
 300 // support.
 301 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
 302                                                          size_t size) {
 303   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 304     // We are asked to check a size in HeapWords,
 305     // but the memory is mangled in juint words.
 306     juint* start = (juint*) (addr + skip_header_HeapWords());
 307     juint* end   = (juint*) (addr + size);
 308     for (juint* slot = start; slot < end; slot += 1) {
 309       assert(*slot == badHeapWordVal,
 310              "Found non badHeapWordValue in pre-allocation check");
 311     }
 312   }
 313 }
 314 #endif
 315 
 316 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
 317                                                bool is_tlab,
 318                                                bool first_only) {
 319   HeapWord* res;
 320   for (int i = 0; i < _n_gens; i++) {
 321     if (_gens[i]->should_allocate(size, is_tlab)) {
 322       res = _gens[i]->allocate(size, is_tlab);
 323       if (res != NULL) return res;
 324       else if (first_only) break;
 325     }
 326   }
 327   // Otherwise...
 328   return NULL;




 329 }
 330 
 331 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
 332                                          bool* gc_overhead_limit_was_exceeded) {
 333   return collector_policy()->mem_allocate_work(size,
 334                                                false /* is_tlab */,
 335                                                gc_overhead_limit_was_exceeded);
 336 }
 337 
 338 bool GenCollectedHeap::must_clear_all_soft_refs() {
 339   return _gc_cause == GCCause::_last_ditch_collection;
 340 }
 341 
 342 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
 343   return UseConcMarkSweepGC &&
 344          ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
 345           (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
 346 }
 347 
 348 void GenCollectedHeap::do_collection(bool  full,
 349                                      bool   clear_all_soft_refs,
 350                                      size_t size,
 351                                      bool   is_tlab,
 352                                      int    max_level) {
 353   bool prepared_for_verification = false;
 354   ResourceMark rm;
 355   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 356 
 357   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 358   assert(my_thread->is_VM_thread() ||
 359          my_thread->is_ConcurrentGC_thread(),
 360          "incorrect thread type capability");
 361   assert(Heap_lock->is_locked(),
 362          "the requesting thread should have the Heap_lock");
 363   guarantee(!is_gc_active(), "collection is not reentrant");
 364   assert(max_level < n_gens(), "sanity check");
 365 
 366   if (GC_locker::check_active_before_gc()) {
 367     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 368   }
 369 
 370   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 371                           collector_policy()->should_clear_all_soft_refs();
 372 
 373   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 374 
 375   const size_t metadata_prev_used = MetaspaceAux::used_bytes();
 376 
 377   print_heap_before_gc();
 378 
 379   {
 380     FlagSetting fl(_is_gc_active, true);
 381 
 382     bool complete = full && (max_level == (n_gens()-1));
 383     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 384     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
 385     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 386     // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 387     // so we can assume here that the next GC id is what we want.
 388     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
 389 
 390     gc_prologue(complete);
 391     increment_total_collections(complete);
 392 
 393     size_t gch_prev_used = used();
 394 
 395     int starting_level = 0;
 396     if (full) {
 397       // Search for the oldest generation which will collect all younger
 398       // generations, and start collection loop there.
 399       for (int i = max_level; i >= 0; i--) {
 400         if (_gens[i]->full_collects_younger_generations()) {
 401           starting_level = i;
 402           break;
 403         }
 404       }
 405     }
 406 
 407     bool must_restore_marks_for_biased_locking = false;
 408 
 409     int max_level_collected = starting_level;
 410     for (int i = starting_level; i <= max_level; i++) {
 411       if (_gens[i]->should_collect(full, size, is_tlab)) {
 412         if (i == n_gens() - 1) {  // a major collection is to happen
 413           if (!complete) {
 414             // The full_collections increment was missed above.
 415             increment_total_full_collections();
 416           }
 417           pre_full_gc_dump(NULL);    // do any pre full gc dumps
 418         }
 419         // Timer for individual generations. Last argument is false: no CR
 420         // FIXME: We should try to start the timing earlier to cover more of the GC pause
 421         // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 422         // so we can assume here that the next GC id is what we want.
 423         GCTraceTime t1(_gens[i]->short_name(), PrintGCDetails, false, NULL, GCId::peek());
 424         TraceCollectorStats tcs(_gens[i]->counters());
 425         TraceMemoryManagerStats tmms(_gens[i]->kind(),gc_cause());
 426 
 427         size_t prev_used = _gens[i]->used();
 428         _gens[i]->stat_record()->invocations++;
 429         _gens[i]->stat_record()->accumulated_time.start();
 430 
 431         // Must be done anew before each collection because
 432         // a previous collection will do mangling and will
 433         // change top of some spaces.
 434         record_gen_tops_before_GC();
 435 
 436         if (PrintGC && Verbose) {
 437           gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
 438                      i,
 439                      _gens[i]->stat_record()->invocations,
 440                      size*HeapWordSize);
 441         }
 442 
 443         if (VerifyBeforeGC && i >= VerifyGCLevel &&
 444             total_collections() >= VerifyGCStartAt) {
 445           HandleMark hm;  // Discard invalid handles created during verification
 446           if (!prepared_for_verification) {
 447             prepare_for_verify();
 448             prepared_for_verification = true;
 449           }
 450           Universe::verify(" VerifyBeforeGC:");
 451         }
 452         COMPILER2_PRESENT(DerivedPointerTable::clear());
 453 
 454         if (!must_restore_marks_for_biased_locking &&
 455             _gens[i]->performs_in_place_marking()) {
 456           // We perform this mark word preservation work lazily
 457           // because it's only at this point that we know whether we
 458           // absolutely have to do it; we want to avoid doing it for
 459           // scavenge-only collections where it's unnecessary
 460           must_restore_marks_for_biased_locking = true;
 461           BiasedLocking::preserve_marks();
 462         }
 463 
 464         // Do collection work
 465         {
 466           // Note on ref discovery: For what appear to be historical reasons,
 467           // GCH enables and disabled (by enqueing) refs discovery.
 468           // In the future this should be moved into the generation's
 469           // collect method so that ref discovery and enqueueing concerns
 470           // are local to a generation. The collect method could return
 471           // an appropriate indication in the case that notification on
 472           // the ref lock was needed. This will make the treatment of
 473           // weak refs more uniform (and indeed remove such concerns
 474           // from GCH). XXX
 475 
 476           HandleMark hm;  // Discard invalid handles created during gc
 477           save_marks();   // save marks for all gens
 478           // We want to discover references, but not process them yet.
 479           // This mode is disabled in process_discovered_references if the
 480           // generation does some collection work, or in
 481           // enqueue_discovered_references if the generation returns
 482           // without doing any work.
 483           ReferenceProcessor* rp = _gens[i]->ref_processor();
 484           // If the discovery of ("weak") refs in this generation is
 485           // atomic wrt other collectors in this configuration, we
 486           // are guaranteed to have empty discovered ref lists.
 487           if (rp->discovery_is_atomic()) {
 488             rp->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
 489             rp->setup_policy(do_clear_all_soft_refs);
 490           } else {
 491             // collect() below will enable discovery as appropriate
 492           }
 493           _gens[i]->collect(full, do_clear_all_soft_refs, size, is_tlab);
 494           if (!rp->enqueuing_is_done()) {
 495             rp->enqueue_discovered_references();
 496           } else {
 497             rp->set_enqueuing_is_done(false);
 498           }
 499           rp->verify_no_references_recorded();
 500         }
 501         max_level_collected = i;
 502 
 503         // Determine if allocation request was met.
 504         if (size > 0) {
 505           if (!is_tlab || _gens[i]->supports_tlab_allocation()) {
 506             if (size*HeapWordSize <= _gens[i]->unsafe_max_alloc_nogc()) {
 507               size = 0;
 508             }
 509           }
 510         }
 511 
 512         COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 513 
 514         _gens[i]->stat_record()->accumulated_time.stop();
 515 
 516         update_gc_stats(i, full);
 517 
 518         if (VerifyAfterGC && i >= VerifyGCLevel &&
 519             total_collections() >= VerifyGCStartAt) {
 520           HandleMark hm;  // Discard invalid handles created during verification
 521           Universe::verify(" VerifyAfterGC:");
 522         }
 523 
 524         if (PrintGCDetails) {
 525           gclog_or_tty->print(":");
 526           _gens[i]->print_heap_change(prev_used);
 527         }





















 528       }



























































 529     }
 530 
 531     // Update "complete" boolean wrt what actually transpired --
 532     // for instance, a promotion failure could have led to
 533     // a whole heap collection.
 534     complete = complete || (max_level_collected == n_gens() - 1);
 535 
 536     if (complete) { // We did a "major" collection
 537       // FIXME: See comment at pre_full_gc_dump call
 538       post_full_gc_dump(NULL);   // do any post full gc dumps
 539     }
 540 
 541     if (PrintGCDetails) {
 542       print_heap_change(gch_prev_used);
 543 
 544       // Print metaspace info for full GC with PrintGCDetails flag.
 545       if (complete) {
 546         MetaspaceAux::print_metaspace_change(metadata_prev_used);
 547       }
 548     }
 549 
 550     for (int j = max_level_collected; j >= 0; j -= 1) {
 551       // Adjust generation sizes.
 552       _gens[j]->compute_new_size();

 553     }

 554 
 555     if (complete) {
 556       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 557       ClassLoaderDataGraph::purge();
 558       MetaspaceAux::verify_metrics();
 559       // Resize the metaspace capacity after full collections
 560       MetaspaceGC::compute_new_size();
 561       update_full_collections_completed();
 562     }
 563 
 564     // Track memory usage and detect low memory after GC finishes
 565     MemoryService::track_memory_usage();
 566 
 567     gc_epilogue(complete);
 568 
 569     if (must_restore_marks_for_biased_locking) {
 570       BiasedLocking::restore_marks();
 571     }
 572   }
 573 
 574   print_heap_after_gc();
 575 
 576 #ifdef TRACESPINNING
 577   ParallelTaskTerminator::print_termination_counts();
 578 #endif
 579 }
 580 
 581 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 582   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 583 }
 584 
 585 void GenCollectedHeap::set_par_threads(uint t) {
 586   SharedHeap::set_par_threads(t);
 587   _gen_process_roots_tasks->set_n_threads(t);
 588 }
 589 
 590 void GenCollectedHeap::
 591 gen_process_roots(int level,
 592                   bool younger_gens_as_roots,
 593                   bool activate_scope,
 594                   SharedHeap::ScanningOption so,
 595                   OopsInGenClosure* not_older_gens,
 596                   OopsInGenClosure* weak_roots,
 597                   OopsInGenClosure* older_gens,
 598                   CLDClosure* cld_closure,
 599                   CLDClosure* weak_cld_closure,
 600                   CodeBlobClosure* code_closure) {
 601 
 602   // General roots.
 603   SharedHeap::process_roots(activate_scope, so,
 604                             not_older_gens, weak_roots,
 605                             cld_closure, weak_cld_closure,
 606                             code_closure);
 607 
 608   if (younger_gens_as_roots) {
 609     if (!_gen_process_roots_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 610       for (int i = 0; i < level; i++) {
 611         not_older_gens->set_generation(_gens[i]);
 612         _gens[i]->oop_iterate(not_older_gens);
 613       }
 614       not_older_gens->reset_generation();
 615     }
 616   }
 617   // When collection is parallel, all threads get to cooperate to do
 618   // older-gen scanning.
 619   for (int i = level+1; i < _n_gens; i++) {
 620     older_gens->set_generation(_gens[i]);
 621     rem_set()->younger_refs_iterate(_gens[i], older_gens);
 622     older_gens->reset_generation();
 623   }
 624 
 625   _gen_process_roots_tasks->all_tasks_completed();
 626 }
 627 
 628 void GenCollectedHeap::
 629 gen_process_roots(int level,
 630                   bool younger_gens_as_roots,
 631                   bool activate_scope,
 632                   SharedHeap::ScanningOption so,
 633                   bool only_strong_roots,
 634                   OopsInGenClosure* not_older_gens,
 635                   OopsInGenClosure* older_gens,
 636                   CLDClosure* cld_closure) {
 637 
 638   const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
 639 
 640   bool is_moving_collection = false;
 641   if (level == 0 || is_adjust_phase) {
 642     // young collections are always moving
 643     is_moving_collection = true;
 644   }
 645 
 646   MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
 647   CodeBlobClosure* code_closure = &mark_code_closure;
 648 
 649   gen_process_roots(level,
 650                     younger_gens_as_roots,
 651                     activate_scope, so,
 652                     not_older_gens, only_strong_roots ? NULL : not_older_gens,
 653                     older_gens,
 654                     cld_closure, only_strong_roots ? NULL : cld_closure,
 655                     code_closure);
 656 
 657 }
 658 
 659 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
 660   SharedHeap::process_weak_roots(root_closure);
 661   // "Local" "weak" refs
 662   for (int i = 0; i < _n_gens; i++) {
 663     _gens[i]->ref_processor()->weak_oops_do(root_closure);
 664   }
 665 }
 666 
 667 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 668 void GenCollectedHeap::                                                 \
 669 oop_since_save_marks_iterate(int level,                                 \
 670                              OopClosureType* cur,                       \
 671                              OopClosureType* older) {                   \
 672   _gens[level]->oop_since_save_marks_iterate##nv_suffix(cur);           \
 673   for (int i = level+1; i < n_gens(); i++) {                            \
 674     _gens[i]->oop_since_save_marks_iterate##nv_suffix(older);           \


 675   }                                                                     \
 676 }
 677 
 678 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 679 
 680 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 681 
 682 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
 683   for (int i = level; i < _n_gens; i++) {
 684     if (!_gens[i]->no_allocs_since_save_marks()) return false;
 685   }

 686   return true;
 687 }
 688 
 689 bool GenCollectedHeap::supports_inline_contig_alloc() const {
 690   return _gens[0]->supports_inline_contig_alloc();
 691 }
 692 
 693 HeapWord** GenCollectedHeap::top_addr() const {
 694   return _gens[0]->top_addr();
 695 }
 696 
 697 HeapWord** GenCollectedHeap::end_addr() const {
 698   return _gens[0]->end_addr();
 699 }
 700 
 701 // public collection interfaces
 702 
 703 void GenCollectedHeap::collect(GCCause::Cause cause) {
 704   if (should_do_concurrent_full_gc(cause)) {
 705 #if INCLUDE_ALL_GCS
 706     // mostly concurrent full collection
 707     collect_mostly_concurrent(cause);
 708 #else  // INCLUDE_ALL_GCS
 709     ShouldNotReachHere();
 710 #endif // INCLUDE_ALL_GCS
 711   } else {
 712 #ifdef ASSERT
 713     if (cause == GCCause::_scavenge_alot) {
 714       // minor collection only
 715       collect(cause, 0);
 716     } else {
 717       // Stop-the-world full collection
 718       collect(cause, n_gens() - 1);
 719     }
 720 #else
 721     // Stop-the-world full collection
 722     collect(cause, n_gens() - 1);
 723 #endif
 724   }
 725 }
 726 
 727 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
 728   // The caller doesn't have the Heap_lock
 729   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 730   MutexLocker ml(Heap_lock);
 731   collect_locked(cause, max_level);
 732 }
 733 
 734 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
 735   // The caller has the Heap_lock
 736   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
 737   collect_locked(cause, n_gens() - 1);
 738 }
 739 
 740 // this is the private collection interface
 741 // The Heap_lock is expected to be held on entry.
 742 
 743 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
 744   // Read the GC count while holding the Heap_lock
 745   unsigned int gc_count_before      = total_collections();
 746   unsigned int full_gc_count_before = total_full_collections();
 747   {
 748     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
 749     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
 750                          cause, max_level);
 751     VMThread::execute(&op);
 752   }
 753 }
 754 
 755 #if INCLUDE_ALL_GCS
 756 bool GenCollectedHeap::create_cms_collector() {
 757 
 758   assert(_gens[1]->kind() == Generation::ConcurrentMarkSweep,
 759          "Unexpected generation kinds");
 760   // Skip two header words in the block content verification
 761   NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
 762   CMSCollector* collector = new CMSCollector(
 763     (ConcurrentMarkSweepGeneration*)_gens[1],
 764     _rem_set->as_CardTableRS(),
 765     (ConcurrentMarkSweepPolicy*) collector_policy());
 766 
 767   if (collector == NULL || !collector->completed_initialization()) {
 768     if (collector) {
 769       delete collector;  // Be nice in embedded situation
 770     }
 771     vm_shutdown_during_initialization("Could not create CMS collector");
 772     return false;
 773   }
 774   return true;  // success
 775 }
 776 
 777 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
 778   assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
 779 
 780   MutexLocker ml(Heap_lock);
 781   // Read the GC counts while holding the Heap_lock
 782   unsigned int full_gc_count_before = total_full_collections();
 783   unsigned int gc_count_before      = total_collections();
 784   {
 785     MutexUnlocker mu(Heap_lock);
 786     VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
 787     VMThread::execute(&op);
 788   }
 789 }
 790 #endif // INCLUDE_ALL_GCS
 791 
 792 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
 793    do_full_collection(clear_all_soft_refs, _n_gens - 1);
 794 }
 795 
 796 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 797                                           int max_level) {
 798   int local_max_level;
 799   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 800       gc_cause() == GCCause::_gc_locker) {
 801     local_max_level = 0;
 802   } else {
 803     local_max_level = max_level;
 804   }
 805 
 806   do_collection(true                 /* full */,
 807                 clear_all_soft_refs  /* clear_all_soft_refs */,
 808                 0                    /* size */,
 809                 false                /* is_tlab */,
 810                 local_max_level      /* max_level */);
 811   // Hack XXX FIX ME !!!
 812   // A scavenge may not have been attempted, or may have
 813   // been attempted and failed, because the old gen was too full
 814   if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
 815       incremental_collection_will_fail(false /* don't consult_young */)) {
 816     if (PrintGCDetails) {
 817       gclog_or_tty->print_cr("GC locker: Trying a full collection "
 818                              "because scavenge failed");
 819     }
 820     // This time allow the old gen to be collected as well
 821     do_collection(true                 /* full */,
 822                   clear_all_soft_refs  /* clear_all_soft_refs */,
 823                   0                    /* size */,
 824                   false                /* is_tlab */,
 825                   n_gens() - 1         /* max_level */);
 826   }
 827 }
 828 
 829 bool GenCollectedHeap::is_in_young(oop p) {
 830   bool result = ((HeapWord*)p) < _gens[_n_gens - 1]->reserved().start();
 831   assert(result == _gens[0]->is_in_reserved(p),
 832          err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
 833   return result;
 834 }
 835 
 836 // Returns "TRUE" iff "p" points into the committed areas of the heap.
 837 bool GenCollectedHeap::is_in(const void* p) const {
 838   #ifndef ASSERT
 839   guarantee(VerifyBeforeGC      ||
 840             VerifyDuringGC      ||
 841             VerifyBeforeExit    ||
 842             VerifyDuringStartup ||
 843             PrintAssembly       ||
 844             tty->count() != 0   ||   // already printing
 845             VerifyAfterGC       ||
 846     VMError::fatal_error_in_progress(), "too expensive");
 847 
 848   #endif
 849   // This might be sped up with a cache of the last generation that
 850   // answered yes.
 851   for (int i = 0; i < _n_gens; i++) {
 852     if (_gens[i]->is_in(p)) return true;
 853   }
 854   // Otherwise...
 855   return false;
 856 }
 857 
 858 #ifdef ASSERT
 859 // Don't implement this by using is_in_young().  This method is used
 860 // in some cases to check that is_in_young() is correct.
 861 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
 862   assert(is_in_reserved(p) || p == NULL,
 863     "Does not work if address is non-null and outside of the heap");
 864   return p < _gens[_n_gens - 2]->reserved().end() && p != NULL;
 865 }
 866 #endif
 867 
 868 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
 869   for (int i = 0; i < _n_gens; i++) {
 870     _gens[i]->oop_iterate(cl);
 871   }
 872 }
 873 
 874 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
 875   for (int i = 0; i < _n_gens; i++) {
 876     _gens[i]->object_iterate(cl);
 877   }
 878 }
 879 
 880 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
 881   for (int i = 0; i < _n_gens; i++) {
 882     _gens[i]->safe_object_iterate(cl);
 883   }
 884 }
 885 
 886 Space* GenCollectedHeap::space_containing(const void* addr) const {
 887   for (int i = 0; i < _n_gens; i++) {
 888     Space* res = _gens[i]->space_containing(addr);
 889     if (res != NULL) return res;
 890   }
 891   // Otherwise...
 892   assert(false, "Could not find containing space");
 893   return NULL;
 894 }
 895 
 896 
 897 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
 898   assert(is_in_reserved(addr), "block_start of address outside of heap");
 899   for (int i = 0; i < _n_gens; i++) {
 900     if (_gens[i]->is_in_reserved(addr)) {
 901       assert(_gens[i]->is_in(addr),
 902              "addr should be in allocated part of generation");
 903       return _gens[i]->block_start(addr);
 904     }
 905   }
 906   assert(false, "Some generation should contain the address");
 907   return NULL;


 908 }
 909 
 910 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
 911   assert(is_in_reserved(addr), "block_size of address outside of heap");
 912   for (int i = 0; i < _n_gens; i++) {
 913     if (_gens[i]->is_in_reserved(addr)) {
 914       assert(_gens[i]->is_in(addr),
 915              "addr should be in allocated part of generation");
 916       return _gens[i]->block_size(addr);
 917     }
 918   }
 919   assert(false, "Some generation should contain the address");
 920   return 0;

 921 }
 922 
 923 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
 924   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
 925   assert(block_start(addr) == addr, "addr must be a block start");
 926   for (int i = 0; i < _n_gens; i++) {
 927     if (_gens[i]->is_in_reserved(addr)) {
 928       return _gens[i]->block_is_obj(addr);
 929     }
 930   }
 931   assert(false, "Some generation should contain the address");
 932   return false;

 933 }
 934 
 935 bool GenCollectedHeap::supports_tlab_allocation() const {
 936   for (int i = 0; i < _n_gens; i += 1) {
 937     if (_gens[i]->supports_tlab_allocation()) {
 938       return true;
 939     }
 940   }
 941   return false;
 942 }
 943 
 944 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
 945   size_t result = 0;
 946   for (int i = 0; i < _n_gens; i += 1) {
 947     if (_gens[i]->supports_tlab_allocation()) {
 948       result += _gens[i]->tlab_capacity();
 949     }
 950   }
 951   return result;
 952 }
 953 
 954 size_t GenCollectedHeap::tlab_used(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_used();
 959     }
 960   }
 961   return result;
 962 }
 963 
 964 size_t GenCollectedHeap::unsafe_max_tlab_alloc(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]->unsafe_max_tlab_alloc();
 969     }
 970   }
 971   return result;
 972 }
 973 
 974 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
 975   bool gc_overhead_limit_was_exceeded;
 976   return collector_policy()->mem_allocate_work(size /* size */,
 977                                                true /* is_tlab */,
 978                                                &gc_overhead_limit_was_exceeded);
 979 }
 980 
 981 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
 982 // from the list headed by "*prev_ptr".
 983 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
 984   bool first = true;
 985   size_t min_size = 0;   // "first" makes this conceptually infinite.
 986   ScratchBlock **smallest_ptr, *smallest;
 987   ScratchBlock  *cur = *prev_ptr;
 988   while (cur) {
 989     assert(*prev_ptr == cur, "just checking");
 990     if (first || cur->num_words < min_size) {
 991       smallest_ptr = prev_ptr;
 992       smallest     = cur;
 993       min_size     = smallest->num_words;
 994       first        = false;
 995     }
 996     prev_ptr = &cur->next;
 997     cur     =  cur->next;
 998   }
 999   smallest      = *smallest_ptr;
1000   *smallest_ptr = smallest->next;
1001   return smallest;
1002 }
1003 
1004 // Sort the scratch block list headed by res into decreasing size order,
1005 // and set "res" to the result.
1006 static void sort_scratch_list(ScratchBlock*& list) {
1007   ScratchBlock* sorted = NULL;
1008   ScratchBlock* unsorted = list;
1009   while (unsorted) {
1010     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1011     smallest->next  = sorted;
1012     sorted          = smallest;
1013   }
1014   list = sorted;
1015 }
1016 
1017 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1018                                                size_t max_alloc_words) {
1019   ScratchBlock* res = NULL;
1020   for (int i = 0; i < _n_gens; i++) {
1021     _gens[i]->contribute_scratch(res, requestor, max_alloc_words);
1022   }
1023   sort_scratch_list(res);
1024   return res;
1025 }
1026 
1027 void GenCollectedHeap::release_scratch() {
1028   for (int i = 0; i < _n_gens; i++) {
1029     _gens[i]->reset_scratch();
1030   }
1031 }
1032 
1033 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1034   void do_generation(Generation* gen) {
1035     gen->prepare_for_verify();
1036   }
1037 };
1038 
1039 void GenCollectedHeap::prepare_for_verify() {
1040   ensure_parsability(false);        // no need to retire TLABs
1041   GenPrepareForVerifyClosure blk;
1042   generation_iterate(&blk, false);
1043 }
1044 
1045 
1046 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1047                                           bool old_to_young) {
1048   if (old_to_young) {
1049     for (int i = _n_gens-1; i >= 0; i--) {
1050       cl->do_generation(_gens[i]);
1051     }
1052   } else {
1053     for (int i = 0; i < _n_gens; i++) {
1054       cl->do_generation(_gens[i]);
1055     }
1056   }
1057 }
1058 
1059 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1060   for (int i = 0; i < _n_gens; i++) {
1061     _gens[i]->space_iterate(cl, true);
1062   }
1063 }
1064 
1065 bool GenCollectedHeap::is_maximal_no_gc() const {
1066   for (int i = 0; i < _n_gens; i++) {
1067     if (!_gens[i]->is_maximal_no_gc()) {
1068       return false;
1069     }
1070   }
1071   return true;
1072 }
1073 
1074 void GenCollectedHeap::save_marks() {
1075   for (int i = 0; i < _n_gens; i++) {
1076     _gens[i]->save_marks();
1077   }
1078 }
1079 
1080 GenCollectedHeap* GenCollectedHeap::heap() {
1081   assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1082   assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1083   return _gch;
1084 }
1085 
1086 
1087 void GenCollectedHeap::prepare_for_compaction() {
1088   guarantee(_n_gens = 2, "Wrong number of generations");
1089   Generation* old_gen = _gens[1];
1090   // Start by compacting into same gen.
1091   CompactPoint cp(old_gen);
1092   old_gen->prepare_for_compaction(&cp);
1093   Generation* young_gen = _gens[0];
1094   young_gen->prepare_for_compaction(&cp);
1095 }
1096 
1097 GCStats* GenCollectedHeap::gc_stats(int level) const {
1098   return _gens[level]->gc_stats();




1099 }
1100 
1101 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1102   for (int i = _n_gens-1; i >= 0; i--) {
1103     Generation* g = _gens[i];
1104     if (!silent) {
1105       gclog_or_tty->print("%s", g->name());
1106       gclog_or_tty->print(" ");
1107     }
1108     g->verify();




1109   }


1110   if (!silent) {
1111     gclog_or_tty->print("remset ");
1112   }
1113   rem_set()->verify();
1114 }
1115 
1116 void GenCollectedHeap::print_on(outputStream* st) const {
1117   for (int i = 0; i < _n_gens; i++) {
1118     _gens[i]->print_on(st);
1119   }
1120   MetaspaceAux::print_on(st);
1121 }
1122 
1123 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1124   if (workers() != NULL) {
1125     workers()->threads_do(tc);
1126   }
1127 #if INCLUDE_ALL_GCS
1128   if (UseConcMarkSweepGC) {
1129     ConcurrentMarkSweepThread::threads_do(tc);
1130   }
1131 #endif // INCLUDE_ALL_GCS
1132 }
1133 
1134 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1135 #if INCLUDE_ALL_GCS
1136   if (UseParNewGC) {
1137     workers()->print_worker_threads_on(st);
1138   }
1139   if (UseConcMarkSweepGC) {
1140     ConcurrentMarkSweepThread::print_all_on(st);
1141   }
1142 #endif // INCLUDE_ALL_GCS
1143 }
1144 
1145 void GenCollectedHeap::print_on_error(outputStream* st) const {
1146   this->CollectedHeap::print_on_error(st);
1147 
1148 #if INCLUDE_ALL_GCS
1149   if (UseConcMarkSweepGC) {
1150     st->cr();
1151     CMSCollector::print_on_error(st);
1152   }
1153 #endif // INCLUDE_ALL_GCS
1154 }
1155 
1156 void GenCollectedHeap::print_tracing_info() const {
1157   if (TraceYoungGenTime) {
1158     get_gen(0)->print_summary_info();
1159   }
1160   if (TraceOldGenTime) {
1161     get_gen(1)->print_summary_info();
1162   }
1163 }
1164 
1165 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1166   if (PrintGCDetails && Verbose) {
1167     gclog_or_tty->print(" "  SIZE_FORMAT
1168                         "->" SIZE_FORMAT
1169                         "("  SIZE_FORMAT ")",
1170                         prev_used, used(), capacity());
1171   } else {
1172     gclog_or_tty->print(" "  SIZE_FORMAT "K"
1173                         "->" SIZE_FORMAT "K"
1174                         "("  SIZE_FORMAT "K)",
1175                         prev_used / K, used() / K, capacity() / K);
1176   }
1177 }
1178 
1179 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1180  private:
1181   bool _full;
1182  public:
1183   void do_generation(Generation* gen) {
1184     gen->gc_prologue(_full);
1185   }
1186   GenGCPrologueClosure(bool full) : _full(full) {};
1187 };
1188 
1189 void GenCollectedHeap::gc_prologue(bool full) {
1190   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1191 
1192   always_do_update_barrier = false;
1193   // Fill TLAB's and such
1194   CollectedHeap::accumulate_statistics_all_tlabs();
1195   ensure_parsability(true);   // retire TLABs
1196 
1197   // Walk generations
1198   GenGCPrologueClosure blk(full);
1199   generation_iterate(&blk, false);  // not old-to-young.
1200 };
1201 
1202 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1203  private:
1204   bool _full;
1205  public:
1206   void do_generation(Generation* gen) {
1207     gen->gc_epilogue(_full);
1208   }
1209   GenGCEpilogueClosure(bool full) : _full(full) {};
1210 };
1211 
1212 void GenCollectedHeap::gc_epilogue(bool full) {
1213 #ifdef COMPILER2
1214   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1215   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1216   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1217 #endif /* COMPILER2 */
1218 
1219   resize_all_tlabs();
1220 
1221   GenGCEpilogueClosure blk(full);
1222   generation_iterate(&blk, false);  // not old-to-young.
1223 
1224   if (!CleanChunkPoolAsync) {
1225     Chunk::clean_chunk_pool();
1226   }
1227 
1228   MetaspaceCounters::update_performance_counters();
1229   CompressedClassSpaceCounters::update_performance_counters();
1230 
1231   always_do_update_barrier = UseConcMarkSweepGC;
1232 };
1233 
1234 #ifndef PRODUCT
1235 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1236  private:
1237  public:
1238   void do_generation(Generation* gen) {
1239     gen->record_spaces_top();
1240   }
1241 };
1242 
1243 void GenCollectedHeap::record_gen_tops_before_GC() {
1244   if (ZapUnusedHeapArea) {
1245     GenGCSaveTopsBeforeGCClosure blk;
1246     generation_iterate(&blk, false);  // not old-to-young.
1247   }
1248 }
1249 #endif  // not PRODUCT
1250 
1251 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1252  public:
1253   void do_generation(Generation* gen) {
1254     gen->ensure_parsability();
1255   }
1256 };
1257 
1258 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1259   CollectedHeap::ensure_parsability(retire_tlabs);
1260   GenEnsureParsabilityClosure ep_cl;
1261   generation_iterate(&ep_cl, false);
1262 }
1263 
1264 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1265                                               oop obj,
1266                                               size_t obj_size) {
1267   guarantee(old_gen->level() == 1, "We only get here with an old generation");
1268   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1269   HeapWord* result = NULL;
1270 
1271   result = old_gen->expand_and_allocate(obj_size, false);
1272 
1273   if (result != NULL) {
1274     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1275   }
1276   return oop(result);
1277 }
1278 
1279 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1280   jlong _time;   // in ms
1281   jlong _now;    // in ms
1282 
1283  public:
1284   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1285 
1286   jlong time() { return _time; }
1287 
1288   void do_generation(Generation* gen) {
1289     _time = MIN2(_time, gen->time_of_last_gc(_now));
1290   }
1291 };
1292 
1293 jlong GenCollectedHeap::millis_since_last_gc() {
1294   // We need a monotonically non-decreasing time in ms but
1295   // os::javaTimeMillis() does not guarantee monotonicity.
1296   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1297   GenTimeOfLastGCClosure tolgc_cl(now);
1298   // iterate over generations getting the oldest
1299   // time that a generation was collected
1300   generation_iterate(&tolgc_cl, false);
1301 
1302   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1303   // provided the underlying platform provides such a time source
1304   // (and it is bug free). So we still have to guard against getting
1305   // back a time later than 'now'.
1306   jlong retVal = now - tolgc_cl.time();
1307   if (retVal < 0) {
1308     NOT_PRODUCT(warning("time warp: "INT64_FORMAT, (int64_t) retVal);)
1309     return 0;
1310   }
1311   return retVal;
1312 }
--- EOF ---