1 /*
   2  * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/symbolTable.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "classfile/vmSymbols.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "code/icBuffer.hpp"
  31 #include "gc/shared/collectedHeap.inline.hpp"
  32 #include "gc/shared/collectorCounters.hpp"
  33 #include "gc/shared/gcLocker.inline.hpp"
  34 #include "gc/shared/gcTrace.hpp"
  35 #include "gc/shared/gcTraceTime.hpp"
  36 #include "gc/shared/genCollectedHeap.hpp"
  37 #include "gc/shared/genOopClosures.inline.hpp"
  38 #include "gc/shared/generationSpec.hpp"
  39 #include "gc/shared/space.hpp"
  40 #include "gc/shared/strongRootsScope.hpp"
  41 #include "gc/shared/vmGCOperations.hpp"
  42 #include "gc/shared/workgroup.hpp"
  43 #include "memory/filemap.hpp"
  44 #include "memory/resourceArea.hpp"
  45 #include "oops/oop.inline.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/management.hpp"
  53 #include "services/memoryService.hpp"
  54 #include "utilities/macros.hpp"
  55 #include "utilities/stack.inline.hpp"
  56 #include "utilities/vmError.hpp"
  57 #if INCLUDE_ALL_GCS
  58 #include "gc/cms/concurrentMarkSweepThread.hpp"
  59 #include "gc/cms/vmCMSOperations.hpp"
  60 #endif // INCLUDE_ALL_GCS
  61 
  62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
  63 
  64 // The set of potentially parallel tasks in root scanning.
  65 enum GCH_strong_roots_tasks {
  66   GCH_PS_Universe_oops_do,
  67   GCH_PS_JNIHandles_oops_do,
  68   GCH_PS_ObjectSynchronizer_oops_do,
  69   GCH_PS_FlatProfiler_oops_do,
  70   GCH_PS_Management_oops_do,
  71   GCH_PS_SystemDictionary_oops_do,
  72   GCH_PS_ClassLoaderDataGraph_oops_do,
  73   GCH_PS_jvmti_oops_do,
  74   GCH_PS_CodeCache_oops_do,
  75   GCH_PS_younger_gens,
  76   // Leave this one last.
  77   GCH_PS_NumElements
  78 };
  79 
  80 GenCollectedHeap::GenCollectedHeap(GenCollectorPolicy *policy) :
  81   CollectedHeap(),
  82   _rem_set(NULL),
  83   _gen_policy(policy),
  84   _process_strong_tasks(new SubTasksDone(GCH_PS_NumElements)),
  85   _full_collections_completed(0)
  86 {
  87   assert(policy != NULL, "Sanity check");
  88   if (UseConcMarkSweepGC) {
  89     _workers = new WorkGang("GC Thread", ParallelGCThreads,
  90                             /* are_GC_task_threads */true,
  91                             /* are_ConcurrentGC_threads */false);
  92     _workers->initialize_workers();
  93   } else {
  94     // Serial GC does not use workers.
  95     _workers = NULL;
  96   }
  97 }
  98 
  99 jint GenCollectedHeap::initialize() {
 100   CollectedHeap::pre_initialize();
 101 
 102   // While there are no constraints in the GC code that HeapWordSize
 103   // be any particular value, there are multiple other areas in the
 104   // system which believe this to be true (e.g. oop->object_size in some
 105   // cases incorrectly returns the size in wordSize units rather than
 106   // HeapWordSize).
 107   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
 108 
 109   // Allocate space for the heap.
 110 
 111   char* heap_address;
 112   ReservedSpace heap_rs;
 113 
 114   size_t heap_alignment = collector_policy()->heap_alignment();
 115 
 116   heap_address = allocate(heap_alignment, &heap_rs);
 117 
 118   if (!heap_rs.is_reserved()) {
 119     vm_shutdown_during_initialization(
 120       "Could not reserve enough space for object heap");
 121     return JNI_ENOMEM;
 122   }
 123 
 124   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
 125 
 126   _rem_set = collector_policy()->create_rem_set(reserved_region());
 127   set_barrier_set(rem_set()->bs());
 128 
 129   ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
 130   _young_gen = gen_policy()->young_gen_spec()->init(young_rs, rem_set());
 131   heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
 132 
 133   ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
 134   _old_gen = gen_policy()->old_gen_spec()->init(old_rs, rem_set());
 135   clear_incremental_collection_failed();
 136 
 137 #if INCLUDE_ALL_GCS
 138   // If we are running CMS, create the collector responsible
 139   // for collecting the CMS generations.
 140   if (collector_policy()->is_concurrent_mark_sweep_policy()) {
 141     bool success = create_cms_collector();
 142     if (!success) return JNI_ENOMEM;
 143   }
 144 #endif // INCLUDE_ALL_GCS
 145 
 146   return JNI_OK;
 147 }
 148 
 149 char* GenCollectedHeap::allocate(size_t alignment,
 150                                  ReservedSpace* heap_rs){
 151   // Now figure out the total size.
 152   const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
 153   assert(alignment % pageSize == 0, "Must be");
 154 
 155   GenerationSpec* young_spec = gen_policy()->young_gen_spec();
 156   GenerationSpec* old_spec = gen_policy()->old_gen_spec();
 157 
 158   // Check for overflow.
 159   size_t total_reserved = young_spec->max_size() + old_spec->max_size();
 160   if (total_reserved < young_spec->max_size()) {
 161     vm_exit_during_initialization("The size of the object heap + VM data exceeds "
 162                                   "the maximum representable size");
 163   }
 164   assert(total_reserved % alignment == 0,
 165          err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
 166                  SIZE_FORMAT, total_reserved, alignment));
 167 
 168   *heap_rs = Universe::reserve_heap(total_reserved, alignment);
 169   return heap_rs->base();
 170 }
 171 
 172 void GenCollectedHeap::post_initialize() {
 173   CollectedHeap::post_initialize();
 174   ref_processing_init();
 175   GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
 176   guarantee(policy->is_generation_policy(), "Illegal policy type");
 177   assert((_young_gen->kind() == Generation::DefNew) ||
 178          (_young_gen->kind() == Generation::ParNew),
 179     "Wrong youngest generation type");
 180   DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
 181 
 182   assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
 183          _old_gen->kind() == Generation::MarkSweepCompact,
 184     "Wrong generation kind");
 185 
 186   policy->initialize_size_policy(def_new_gen->eden()->capacity(),
 187                                  _old_gen->capacity(),
 188                                  def_new_gen->from()->capacity());
 189   policy->initialize_gc_policy_counters();
 190 }
 191 
 192 void GenCollectedHeap::ref_processing_init() {
 193   _young_gen->ref_processor_init();
 194   _old_gen->ref_processor_init();
 195 }
 196 
 197 size_t GenCollectedHeap::capacity() const {
 198   return _young_gen->capacity() + _old_gen->capacity();
 199 }
 200 
 201 size_t GenCollectedHeap::used() const {
 202   return _young_gen->used() + _old_gen->used();
 203 }
 204 
 205 void GenCollectedHeap::save_used_regions() {
 206   _old_gen->save_used_region();
 207   _young_gen->save_used_region();
 208 }
 209 
 210 size_t GenCollectedHeap::max_capacity() const {
 211   return _young_gen->max_capacity() + _old_gen->max_capacity();
 212 }
 213 
 214 // Update the _full_collections_completed counter
 215 // at the end of a stop-world full GC.
 216 unsigned int GenCollectedHeap::update_full_collections_completed() {
 217   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 218   assert(_full_collections_completed <= _total_full_collections,
 219          "Can't complete more collections than were started");
 220   _full_collections_completed = _total_full_collections;
 221   ml.notify_all();
 222   return _full_collections_completed;
 223 }
 224 
 225 // Update the _full_collections_completed counter, as appropriate,
 226 // at the end of a concurrent GC cycle. Note the conditional update
 227 // below to allow this method to be called by a concurrent collector
 228 // without synchronizing in any manner with the VM thread (which
 229 // may already have initiated a STW full collection "concurrently").
 230 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
 231   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 232   assert((_full_collections_completed <= _total_full_collections) &&
 233          (count <= _total_full_collections),
 234          "Can't complete more collections than were started");
 235   if (count > _full_collections_completed) {
 236     _full_collections_completed = count;
 237     ml.notify_all();
 238   }
 239   return _full_collections_completed;
 240 }
 241 
 242 
 243 #ifndef PRODUCT
 244 // Override of memory state checking method in CollectedHeap:
 245 // Some collectors (CMS for example) can't have badHeapWordVal written
 246 // in the first two words of an object. (For instance , in the case of
 247 // CMS these words hold state used to synchronize between certain
 248 // (concurrent) GC steps and direct allocating mutators.)
 249 // The skip_header_HeapWords() method below, allows us to skip
 250 // over the requisite number of HeapWord's. Note that (for
 251 // generational collectors) this means that those many words are
 252 // skipped in each object, irrespective of the generation in which
 253 // that object lives. The resultant loss of precision seems to be
 254 // harmless and the pain of avoiding that imprecision appears somewhat
 255 // higher than we are prepared to pay for such rudimentary debugging
 256 // support.
 257 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
 258                                                          size_t size) {
 259   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 260     // We are asked to check a size in HeapWords,
 261     // but the memory is mangled in juint words.
 262     juint* start = (juint*) (addr + skip_header_HeapWords());
 263     juint* end   = (juint*) (addr + size);
 264     for (juint* slot = start; slot < end; slot += 1) {
 265       assert(*slot == badHeapWordVal,
 266              "Found non badHeapWordValue in pre-allocation check");
 267     }
 268   }
 269 }
 270 #endif
 271 
 272 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
 273                                                bool is_tlab,
 274                                                bool first_only) {
 275   HeapWord* res = NULL;
 276 
 277   if (_young_gen->should_allocate(size, is_tlab)) {
 278     res = _young_gen->allocate(size, is_tlab);
 279     if (res != NULL || first_only) {
 280       return res;
 281     }
 282   }
 283 
 284   if (_old_gen->should_allocate(size, is_tlab)) {
 285     res = _old_gen->allocate(size, is_tlab);
 286   }
 287 
 288   return res;
 289 }
 290 
 291 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
 292                                          bool* gc_overhead_limit_was_exceeded) {
 293   return collector_policy()->mem_allocate_work(size,
 294                                                false /* is_tlab */,
 295                                                gc_overhead_limit_was_exceeded);
 296 }
 297 
 298 bool GenCollectedHeap::must_clear_all_soft_refs() {
 299   return _gc_cause == GCCause::_last_ditch_collection;
 300 }
 301 
 302 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
 303   if (!UseConcMarkSweepGC) {
 304     return false;
 305   }
 306 
 307   switch (cause) {
 308     case GCCause::_gc_locker:           return GCLockerInvokesConcurrent;
 309     case GCCause::_java_lang_system_gc:
 310     case GCCause::_dcmd_gc_run:         return ExplicitGCInvokesConcurrent;
 311     default:                            return false;
 312   }
 313 }
 314 
 315 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
 316                                           bool is_tlab, bool run_verification, bool clear_soft_refs,
 317                                           bool restore_marks_for_biased_locking) {
 318   // Timer for individual generations. Last argument is false: no CR
 319   // FIXME: We should try to start the timing earlier to cover more of the GC pause
 320   // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 321   // so we can assume here that the next GC id is what we want.
 322   GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
 323   TraceCollectorStats tcs(gen->counters());
 324   TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
 325 
 326   size_t prev_used = gen->used();
 327   gen->stat_record()->invocations++;
 328   gen->stat_record()->accumulated_time.start();
 329 
 330   // Must be done anew before each collection because
 331   // a previous collection will do mangling and will
 332   // change top of some spaces.
 333   record_gen_tops_before_GC();
 334 
 335   if (PrintGC && Verbose) {
 336     // I didn't want to change the logging when removing the level concept,
 337     // but I guess this logging could say young/old or something instead of 0/1.
 338     uint level;
 339     if (heap()->is_young_gen(gen)) {
 340       level = 0;
 341     } else {
 342       level = 1;
 343     }
 344     gclog_or_tty->print("level=%u invoke=%d size=" SIZE_FORMAT,
 345                         level,
 346                         gen->stat_record()->invocations,
 347                         size * HeapWordSize);
 348   }
 349 
 350   if (run_verification && VerifyBeforeGC) {
 351     HandleMark hm;  // Discard invalid handles created during verification
 352     Universe::verify(" VerifyBeforeGC:");
 353   }
 354   COMPILER2_PRESENT(DerivedPointerTable::clear());
 355 
 356   if (restore_marks_for_biased_locking) {
 357     // We perform this mark word preservation work lazily
 358     // because it's only at this point that we know whether we
 359     // absolutely have to do it; we want to avoid doing it for
 360     // scavenge-only collections where it's unnecessary
 361     BiasedLocking::preserve_marks();
 362   }
 363 
 364   // Do collection work
 365   {
 366     // Note on ref discovery: For what appear to be historical reasons,
 367     // GCH enables and disabled (by enqueing) refs discovery.
 368     // In the future this should be moved into the generation's
 369     // collect method so that ref discovery and enqueueing concerns
 370     // are local to a generation. The collect method could return
 371     // an appropriate indication in the case that notification on
 372     // the ref lock was needed. This will make the treatment of
 373     // weak refs more uniform (and indeed remove such concerns
 374     // from GCH). XXX
 375 
 376     HandleMark hm;  // Discard invalid handles created during gc
 377     save_marks();   // save marks for all gens
 378     // We want to discover references, but not process them yet.
 379     // This mode is disabled in process_discovered_references if the
 380     // generation does some collection work, or in
 381     // enqueue_discovered_references if the generation returns
 382     // without doing any work.
 383     ReferenceProcessor* rp = gen->ref_processor();
 384     // If the discovery of ("weak") refs in this generation is
 385     // atomic wrt other collectors in this configuration, we
 386     // are guaranteed to have empty discovered ref lists.
 387     if (rp->discovery_is_atomic()) {
 388       rp->enable_discovery();
 389       rp->setup_policy(clear_soft_refs);
 390     } else {
 391       // collect() below will enable discovery as appropriate
 392     }
 393     gen->collect(full, clear_soft_refs, size, is_tlab);
 394     if (!rp->enqueuing_is_done()) {
 395       rp->enqueue_discovered_references();
 396     } else {
 397       rp->set_enqueuing_is_done(false);
 398     }
 399     rp->verify_no_references_recorded();
 400   }
 401 
 402   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 403 
 404   gen->stat_record()->accumulated_time.stop();
 405 
 406   update_gc_stats(gen, full);
 407 
 408   if (run_verification && VerifyAfterGC) {
 409     HandleMark hm;  // Discard invalid handles created during verification
 410     Universe::verify(" VerifyAfterGC:");
 411   }
 412 
 413   if (PrintGCDetails) {
 414     gclog_or_tty->print(":");
 415     gen->print_heap_change(prev_used);
 416   }
 417 }
 418 
 419 void GenCollectedHeap::do_collection(bool           full,
 420                                      bool           clear_all_soft_refs,
 421                                      size_t         size,
 422                                      bool           is_tlab,
 423                                      GenerationType max_generation) {
 424   ResourceMark rm;
 425   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 426 
 427   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 428   assert(my_thread->is_VM_thread() ||
 429          my_thread->is_ConcurrentGC_thread(),
 430          "incorrect thread type capability");
 431   assert(Heap_lock->is_locked(),
 432          "the requesting thread should have the Heap_lock");
 433   guarantee(!is_gc_active(), "collection is not reentrant");
 434 
 435   if (GC_locker::check_active_before_gc()) {
 436     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 437   }
 438 
 439   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 440                           collector_policy()->should_clear_all_soft_refs();
 441 
 442   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 443 
 444   const size_t metadata_prev_used = MetaspaceAux::used_bytes();
 445 
 446   print_heap_before_gc();
 447 
 448   {
 449     FlagSetting fl(_is_gc_active, true);
 450 
 451     bool complete = full && (max_generation == OldGen);
 452     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 453     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 454     // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 455     // so we can assume here that the next GC id is what we want.
 456     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
 457 
 458     gc_prologue(complete);
 459     increment_total_collections(complete);
 460 
 461     size_t gch_prev_used = used();
 462     bool run_verification = total_collections() >= VerifyGCStartAt;
 463 
 464     bool prepared_for_verification = false;
 465     bool collected_old = false;
 466     bool old_collects_young = complete &&
 467                               _old_gen->full_collects_younger_generations();
 468     if (!old_collects_young &&
 469         _young_gen->should_collect(full, size, is_tlab)) {
 470       if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
 471         prepare_for_verify();
 472         prepared_for_verification = true;
 473       }
 474 
 475       assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
 476       collect_generation(_young_gen,
 477                          full,
 478                          size,
 479                          is_tlab,
 480                          run_verification && VerifyGCLevel <= 0,
 481                          do_clear_all_soft_refs,
 482                          false);
 483 
 484       if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
 485           size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
 486         // Allocation request was met by young GC.
 487         size = 0;
 488       }
 489     }
 490 
 491     bool must_restore_marks_for_biased_locking = false;
 492 
 493     if (max_generation == OldGen && _old_gen->should_collect(full, size, is_tlab)) {
 494       if (!complete) {
 495         // The full_collections increment was missed above.
 496         increment_total_full_collections();
 497       }
 498 
 499       pre_full_gc_dump(NULL);    // do any pre full gc dumps
 500 
 501       if (!prepared_for_verification && run_verification &&
 502           VerifyGCLevel <= 1 && VerifyBeforeGC) {
 503         prepare_for_verify();
 504       }
 505 
 506       assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
 507       collect_generation(_old_gen,
 508                          full,
 509                          size,
 510                          is_tlab,
 511                          run_verification && VerifyGCLevel <= 1,
 512                          do_clear_all_soft_refs,
 513                          true);
 514 
 515       must_restore_marks_for_biased_locking = true;
 516       collected_old = true;
 517     }
 518 
 519     // Update "complete" boolean wrt what actually transpired --
 520     // for instance, a promotion failure could have led to
 521     // a whole heap collection.
 522     complete = complete || collected_old;
 523 
 524     if (complete) { // We did a "major" collection
 525       // FIXME: See comment at pre_full_gc_dump call
 526       post_full_gc_dump(NULL);   // do any post full gc dumps
 527     }
 528 
 529     if (PrintGCDetails) {
 530       print_heap_change(gch_prev_used);
 531 
 532       // Print metaspace info for full GC with PrintGCDetails flag.
 533       if (complete) {
 534         MetaspaceAux::print_metaspace_change(metadata_prev_used);
 535       }
 536     }
 537 
 538     // Adjust generation sizes.
 539     if (collected_old) {
 540       _old_gen->compute_new_size();
 541     }
 542     _young_gen->compute_new_size();
 543 
 544     if (complete) {
 545       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 546       ClassLoaderDataGraph::purge();
 547       MetaspaceAux::verify_metrics();
 548       // Resize the metaspace capacity after full collections
 549       MetaspaceGC::compute_new_size();
 550       update_full_collections_completed();
 551     }
 552 
 553     // Track memory usage and detect low memory after GC finishes
 554     MemoryService::track_memory_usage();
 555 
 556     gc_epilogue(complete);
 557 
 558     if (must_restore_marks_for_biased_locking) {
 559       BiasedLocking::restore_marks();
 560     }
 561   }
 562 
 563   print_heap_after_gc();
 564 
 565 #ifdef TRACESPINNING
 566   ParallelTaskTerminator::print_termination_counts();
 567 #endif
 568 }
 569 
 570 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 571   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 572 }
 573 
 574 #ifdef ASSERT
 575 class AssertNonScavengableClosure: public OopClosure {
 576 public:
 577   virtual void do_oop(oop* p) {
 578     assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
 579       "Referent should not be scavengable.");  }
 580   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 581 };
 582 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 583 #endif
 584 
 585 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
 586                                      ScanningOption so,
 587                                      OopClosure* strong_roots,
 588                                      OopClosure* weak_roots,
 589                                      CLDClosure* strong_cld_closure,
 590                                      CLDClosure* weak_cld_closure,
 591                                      CodeBlobClosure* code_roots) {
 592   // General roots.
 593   assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
 594   assert(code_roots != NULL, "code root closure should always be set");
 595   // _n_termination for _process_strong_tasks should be set up stream
 596   // in a method not running in a GC worker.  Otherwise the GC worker
 597   // could be trying to change the termination condition while the task
 598   // is executing in another GC worker.
 599 
 600   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
 601     ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
 602   }
 603 
 604   // Some CLDs contained in the thread frames should be considered strong.
 605   // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
 606   CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
 607   // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
 608   CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
 609 
 610   bool is_par = scope->n_threads() > 1;
 611   Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
 612 
 613   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
 614     Universe::oops_do(strong_roots);
 615   }
 616   // Global (strong) JNI handles
 617   if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
 618     JNIHandles::oops_do(strong_roots);
 619   }
 620 
 621   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
 622     ObjectSynchronizer::oops_do(strong_roots);
 623   }
 624   if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
 625     FlatProfiler::oops_do(strong_roots);
 626   }
 627   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
 628     Management::oops_do(strong_roots);
 629   }
 630   if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
 631     JvmtiExport::oops_do(strong_roots);
 632   }
 633 
 634   if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
 635     SystemDictionary::roots_oops_do(strong_roots, weak_roots);
 636   }
 637 
 638   // All threads execute the following. A specific chunk of buckets
 639   // from the StringTable are the individual tasks.
 640   if (weak_roots != NULL) {
 641     if (is_par) {
 642       StringTable::possibly_parallel_oops_do(weak_roots);
 643     } else {
 644       StringTable::oops_do(weak_roots);
 645     }
 646   }
 647 
 648   if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
 649     if (so & SO_ScavengeCodeCache) {
 650       assert(code_roots != NULL, "must supply closure for code cache");
 651 
 652       // We only visit parts of the CodeCache when scavenging.
 653       CodeCache::scavenge_root_nmethods_do(code_roots);
 654     }
 655     if (so & SO_AllCodeCache) {
 656       assert(code_roots != NULL, "must supply closure for code cache");
 657 
 658       // CMSCollector uses this to do intermediate-strength collections.
 659       // We scan the entire code cache, since CodeCache::do_unloading is not called.
 660       CodeCache::blobs_do(code_roots);
 661     }
 662     // Verify that the code cache contents are not subject to
 663     // movement by a scavenging collection.
 664     DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
 665     DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
 666   }
 667 }
 668 
 669 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope,
 670                                          GenerationType type,
 671                                          bool younger_gens_as_roots,
 672                                          ScanningOption so,
 673                                          bool only_strong_roots,
 674                                          OopsInGenClosure* not_older_gens,
 675                                          OopsInGenClosure* older_gens,
 676                                          CLDClosure* cld_closure) {
 677   const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
 678 
 679   bool is_moving_collection = false;
 680   if (type == YoungGen || is_adjust_phase) {
 681     // young collections are always moving
 682     is_moving_collection = true;
 683   }
 684 
 685   MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
 686   OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
 687   CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
 688 
 689   process_roots(scope, so,
 690                 not_older_gens, weak_roots,
 691                 cld_closure, weak_cld_closure,
 692                 &mark_code_closure);
 693 
 694   if (younger_gens_as_roots) {
 695     if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 696       if (type == OldGen) {
 697         not_older_gens->set_generation(_young_gen);
 698         _young_gen->oop_iterate(not_older_gens);
 699       }
 700       not_older_gens->reset_generation();
 701     }
 702   }
 703   // When collection is parallel, all threads get to cooperate to do
 704   // old generation scanning.
 705   if (type == YoungGen) {
 706     older_gens->set_generation(_old_gen);
 707     rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
 708     older_gens->reset_generation();
 709   }
 710 
 711   _process_strong_tasks->all_tasks_completed(scope->n_threads());
 712 }
 713 
 714 
 715 class AlwaysTrueClosure: public BoolObjectClosure {
 716 public:
 717   bool do_object_b(oop p) { return true; }
 718 };
 719 static AlwaysTrueClosure always_true;
 720 
 721 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
 722   JNIHandles::weak_oops_do(&always_true, root_closure);
 723   _young_gen->ref_processor()->weak_oops_do(root_closure);
 724   _old_gen->ref_processor()->weak_oops_do(root_closure);
 725 }
 726 
 727 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 728 void GenCollectedHeap::                                                 \
 729 oop_since_save_marks_iterate(GenerationType gen,                        \
 730                              OopClosureType* cur,                       \
 731                              OopClosureType* older) {                   \
 732   if (gen == YoungGen) {                              \
 733     _young_gen->oop_since_save_marks_iterate##nv_suffix(cur);           \
 734     _old_gen->oop_since_save_marks_iterate##nv_suffix(older);           \
 735   } else {                                                              \
 736     _old_gen->oop_since_save_marks_iterate##nv_suffix(cur);             \
 737   }                                                                     \
 738 }
 739 
 740 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 741 
 742 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 743 
 744 bool GenCollectedHeap::no_allocs_since_save_marks() {
 745   return _young_gen->no_allocs_since_save_marks() &&
 746          _old_gen->no_allocs_since_save_marks();
 747 }
 748 
 749 bool GenCollectedHeap::supports_inline_contig_alloc() const {
 750   return _young_gen->supports_inline_contig_alloc();
 751 }
 752 
 753 HeapWord** GenCollectedHeap::top_addr() const {
 754   return _young_gen->top_addr();
 755 }
 756 
 757 HeapWord** GenCollectedHeap::end_addr() const {
 758   return _young_gen->end_addr();
 759 }
 760 
 761 // public collection interfaces
 762 
 763 void GenCollectedHeap::collect(GCCause::Cause cause) {
 764   if (should_do_concurrent_full_gc(cause)) {
 765 #if INCLUDE_ALL_GCS
 766     // mostly concurrent full collection
 767     collect_mostly_concurrent(cause);
 768 #else  // INCLUDE_ALL_GCS
 769     ShouldNotReachHere();
 770 #endif // INCLUDE_ALL_GCS
 771   } else if (cause == GCCause::_wb_young_gc) {
 772     // minor collection for WhiteBox API
 773     collect(cause, YoungGen);
 774   } else {
 775 #ifdef ASSERT
 776   if (cause == GCCause::_scavenge_alot) {
 777     // minor collection only
 778     collect(cause, YoungGen);
 779   } else {
 780     // Stop-the-world full collection
 781     collect(cause, OldGen);
 782   }
 783 #else
 784     // Stop-the-world full collection
 785     collect(cause, OldGen);
 786 #endif
 787   }
 788 }
 789 
 790 void GenCollectedHeap::collect(GCCause::Cause cause, GenerationType max_generation) {
 791   // The caller doesn't have the Heap_lock
 792   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 793   MutexLocker ml(Heap_lock);
 794   collect_locked(cause, max_generation);
 795 }
 796 
 797 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
 798   // The caller has the Heap_lock
 799   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
 800   collect_locked(cause, OldGen);
 801 }
 802 
 803 // this is the private collection interface
 804 // The Heap_lock is expected to be held on entry.
 805 
 806 void GenCollectedHeap::collect_locked(GCCause::Cause cause, GenerationType max_generation) {
 807   // Read the GC count while holding the Heap_lock
 808   unsigned int gc_count_before      = total_collections();
 809   unsigned int full_gc_count_before = total_full_collections();
 810   {
 811     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
 812     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
 813                          cause, max_generation);
 814     VMThread::execute(&op);
 815   }
 816 }
 817 
 818 #if INCLUDE_ALL_GCS
 819 bool GenCollectedHeap::create_cms_collector() {
 820 
 821   assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
 822          "Unexpected generation kinds");
 823   // Skip two header words in the block content verification
 824   NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
 825   CMSCollector* collector = new CMSCollector(
 826     (ConcurrentMarkSweepGeneration*)_old_gen,
 827     _rem_set->as_CardTableRS(),
 828     (ConcurrentMarkSweepPolicy*) collector_policy());
 829 
 830   if (collector == NULL || !collector->completed_initialization()) {
 831     if (collector) {
 832       delete collector;  // Be nice in embedded situation
 833     }
 834     vm_shutdown_during_initialization("Could not create CMS collector");
 835     return false;
 836   }
 837   return true;  // success
 838 }
 839 
 840 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
 841   assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
 842 
 843   MutexLocker ml(Heap_lock);
 844   // Read the GC counts while holding the Heap_lock
 845   unsigned int full_gc_count_before = total_full_collections();
 846   unsigned int gc_count_before      = total_collections();
 847   {
 848     MutexUnlocker mu(Heap_lock);
 849     VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
 850     VMThread::execute(&op);
 851   }
 852 }
 853 #endif // INCLUDE_ALL_GCS
 854 
 855 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
 856    do_full_collection(clear_all_soft_refs, OldGen);
 857 }
 858 
 859 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 860                                           GenerationType last_generation) {
 861   GenerationType local_last_generation;
 862   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 863       gc_cause() == GCCause::_gc_locker) {
 864     local_last_generation = YoungGen;
 865   } else {
 866     local_last_generation = last_generation;
 867   }
 868 
 869   do_collection(true,                   // full
 870                 clear_all_soft_refs,    // clear_all_soft_refs
 871                 0,                      // size
 872                 false,                  // is_tlab
 873                 local_last_generation); // last_generation
 874   // Hack XXX FIX ME !!!
 875   // A scavenge may not have been attempted, or may have
 876   // been attempted and failed, because the old gen was too full
 877   if (local_last_generation == YoungGen && gc_cause() == GCCause::_gc_locker &&
 878       incremental_collection_will_fail(false /* don't consult_young */)) {
 879     if (PrintGCDetails) {
 880       gclog_or_tty->print_cr("GC locker: Trying a full collection "
 881                              "because scavenge failed");
 882     }
 883     // This time allow the old gen to be collected as well
 884     do_collection(true,                // full
 885                   clear_all_soft_refs, // clear_all_soft_refs
 886                   0,                   // size
 887                   false,               // is_tlab
 888                   OldGen);             // last_generation
 889   }
 890 }
 891 
 892 bool GenCollectedHeap::is_in_young(oop p) {
 893   bool result = ((HeapWord*)p) < _old_gen->reserved().start();
 894   assert(result == _young_gen->is_in_reserved(p),
 895          err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
 896   return result;
 897 }
 898 
 899 // Returns "TRUE" iff "p" points into the committed areas of the heap.
 900 bool GenCollectedHeap::is_in(const void* p) const {
 901   return _young_gen->is_in(p) || _old_gen->is_in(p);
 902 }
 903 
 904 #ifdef ASSERT
 905 // Don't implement this by using is_in_young().  This method is used
 906 // in some cases to check that is_in_young() is correct.
 907 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
 908   assert(is_in_reserved(p) || p == NULL,
 909     "Does not work if address is non-null and outside of the heap");
 910   return p < _young_gen->reserved().end() && p != NULL;
 911 }
 912 #endif
 913 
 914 void GenCollectedHeap::oop_iterate_no_header(OopClosure* cl) {
 915   NoHeaderExtendedOopClosure no_header_cl(cl);
 916   oop_iterate(&no_header_cl);
 917 }
 918 
 919 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
 920   _young_gen->oop_iterate(cl);
 921   _old_gen->oop_iterate(cl);
 922 }
 923 
 924 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
 925   _young_gen->object_iterate(cl);
 926   _old_gen->object_iterate(cl);
 927 }
 928 
 929 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
 930   _young_gen->safe_object_iterate(cl);
 931   _old_gen->safe_object_iterate(cl);
 932 }
 933 
 934 Space* GenCollectedHeap::space_containing(const void* addr) const {
 935   Space* res = _young_gen->space_containing(addr);
 936   if (res != NULL) {
 937     return res;
 938   }
 939   res = _old_gen->space_containing(addr);
 940   assert(res != NULL, "Could not find containing space");
 941   return res;
 942 }
 943 
 944 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
 945   assert(is_in_reserved(addr), "block_start of address outside of heap");
 946   if (_young_gen->is_in_reserved(addr)) {
 947     assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
 948     return _young_gen->block_start(addr);
 949   }
 950 
 951   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
 952   assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
 953   return _old_gen->block_start(addr);
 954 }
 955 
 956 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
 957   assert(is_in_reserved(addr), "block_size of address outside of heap");
 958   if (_young_gen->is_in_reserved(addr)) {
 959     assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
 960     return _young_gen->block_size(addr);
 961   }
 962 
 963   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
 964   assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
 965   return _old_gen->block_size(addr);
 966 }
 967 
 968 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
 969   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
 970   assert(block_start(addr) == addr, "addr must be a block start");
 971   if (_young_gen->is_in_reserved(addr)) {
 972     return _young_gen->block_is_obj(addr);
 973   }
 974 
 975   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
 976   return _old_gen->block_is_obj(addr);
 977 }
 978 
 979 bool GenCollectedHeap::supports_tlab_allocation() const {
 980   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
 981   return _young_gen->supports_tlab_allocation();
 982 }
 983 
 984 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
 985   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
 986   if (_young_gen->supports_tlab_allocation()) {
 987     return _young_gen->tlab_capacity();
 988   }
 989   return 0;
 990 }
 991 
 992 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
 993   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
 994   if (_young_gen->supports_tlab_allocation()) {
 995     return _young_gen->tlab_used();
 996   }
 997   return 0;
 998 }
 999 
1000 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1001   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1002   if (_young_gen->supports_tlab_allocation()) {
1003     return _young_gen->unsafe_max_tlab_alloc();
1004   }
1005   return 0;
1006 }
1007 
1008 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1009   bool gc_overhead_limit_was_exceeded;
1010   return collector_policy()->mem_allocate_work(size /* size */,
1011                                                true /* is_tlab */,
1012                                                &gc_overhead_limit_was_exceeded);
1013 }
1014 
1015 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
1016 // from the list headed by "*prev_ptr".
1017 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1018   bool first = true;
1019   size_t min_size = 0;   // "first" makes this conceptually infinite.
1020   ScratchBlock **smallest_ptr, *smallest;
1021   ScratchBlock  *cur = *prev_ptr;
1022   while (cur) {
1023     assert(*prev_ptr == cur, "just checking");
1024     if (first || cur->num_words < min_size) {
1025       smallest_ptr = prev_ptr;
1026       smallest     = cur;
1027       min_size     = smallest->num_words;
1028       first        = false;
1029     }
1030     prev_ptr = &cur->next;
1031     cur     =  cur->next;
1032   }
1033   smallest      = *smallest_ptr;
1034   *smallest_ptr = smallest->next;
1035   return smallest;
1036 }
1037 
1038 // Sort the scratch block list headed by res into decreasing size order,
1039 // and set "res" to the result.
1040 static void sort_scratch_list(ScratchBlock*& list) {
1041   ScratchBlock* sorted = NULL;
1042   ScratchBlock* unsorted = list;
1043   while (unsorted) {
1044     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1045     smallest->next  = sorted;
1046     sorted          = smallest;
1047   }
1048   list = sorted;
1049 }
1050 
1051 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1052                                                size_t max_alloc_words) {
1053   ScratchBlock* res = NULL;
1054   _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1055   _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1056   sort_scratch_list(res);
1057   return res;
1058 }
1059 
1060 void GenCollectedHeap::release_scratch() {
1061   _young_gen->reset_scratch();
1062   _old_gen->reset_scratch();
1063 }
1064 
1065 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1066   void do_generation(Generation* gen) {
1067     gen->prepare_for_verify();
1068   }
1069 };
1070 
1071 void GenCollectedHeap::prepare_for_verify() {
1072   ensure_parsability(false);        // no need to retire TLABs
1073   GenPrepareForVerifyClosure blk;
1074   generation_iterate(&blk, false);
1075 }
1076 
1077 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1078                                           bool old_to_young) {
1079   if (old_to_young) {
1080     cl->do_generation(_old_gen);
1081     cl->do_generation(_young_gen);
1082   } else {
1083     cl->do_generation(_young_gen);
1084     cl->do_generation(_old_gen);
1085   }
1086 }
1087 
1088 bool GenCollectedHeap::is_maximal_no_gc() const {
1089   return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1090 }
1091 
1092 void GenCollectedHeap::save_marks() {
1093   _young_gen->save_marks();
1094   _old_gen->save_marks();
1095 }
1096 
1097 GenCollectedHeap* GenCollectedHeap::heap() {
1098   CollectedHeap* heap = Universe::heap();
1099   assert(heap != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1100   assert(heap->kind() == CollectedHeap::GenCollectedHeap, "Not a GenCollectedHeap");
1101   return (GenCollectedHeap*)heap;
1102 }
1103 
1104 void GenCollectedHeap::prepare_for_compaction() {
1105   // Start by compacting into same gen.
1106   CompactPoint cp(_old_gen);
1107   _old_gen->prepare_for_compaction(&cp);
1108   _young_gen->prepare_for_compaction(&cp);
1109 }
1110 
1111 GCStats* GenCollectedHeap::gc_stats(Generation* gen) const {
1112   return gen->gc_stats();
1113 }
1114 
1115 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1116   if (!silent) {
1117     gclog_or_tty->print("%s", _old_gen->name());
1118     gclog_or_tty->print(" ");
1119   }
1120   _old_gen->verify();
1121 
1122   if (!silent) {
1123     gclog_or_tty->print("%s", _young_gen->name());
1124     gclog_or_tty->print(" ");
1125   }
1126   _young_gen->verify();
1127 
1128   if (!silent) {
1129     gclog_or_tty->print("remset ");
1130   }
1131   rem_set()->verify();
1132 }
1133 
1134 void GenCollectedHeap::print_on(outputStream* st) const {
1135   _young_gen->print_on(st);
1136   _old_gen->print_on(st);
1137   MetaspaceAux::print_on(st);
1138 }
1139 
1140 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1141   if (workers() != NULL) {
1142     workers()->threads_do(tc);
1143   }
1144 #if INCLUDE_ALL_GCS
1145   if (UseConcMarkSweepGC) {
1146     ConcurrentMarkSweepThread::threads_do(tc);
1147   }
1148 #endif // INCLUDE_ALL_GCS
1149 }
1150 
1151 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1152 #if INCLUDE_ALL_GCS
1153   if (UseConcMarkSweepGC) {
1154     workers()->print_worker_threads_on(st);
1155     ConcurrentMarkSweepThread::print_all_on(st);
1156   }
1157 #endif // INCLUDE_ALL_GCS
1158 }
1159 
1160 void GenCollectedHeap::print_on_error(outputStream* st) const {
1161   this->CollectedHeap::print_on_error(st);
1162 
1163 #if INCLUDE_ALL_GCS
1164   if (UseConcMarkSweepGC) {
1165     st->cr();
1166     CMSCollector::print_on_error(st);
1167   }
1168 #endif // INCLUDE_ALL_GCS
1169 }
1170 
1171 void GenCollectedHeap::print_tracing_info() const {
1172   if (TraceYoungGenTime) {
1173     _young_gen->print_summary_info();
1174   }
1175   if (TraceOldGenTime) {
1176     _old_gen->print_summary_info();
1177   }
1178 }
1179 
1180 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1181   if (PrintGCDetails && Verbose) {
1182     gclog_or_tty->print(" "  SIZE_FORMAT
1183                         "->" SIZE_FORMAT
1184                         "("  SIZE_FORMAT ")",
1185                         prev_used, used(), capacity());
1186   } else {
1187     gclog_or_tty->print(" "  SIZE_FORMAT "K"
1188                         "->" SIZE_FORMAT "K"
1189                         "("  SIZE_FORMAT "K)",
1190                         prev_used / K, used() / K, capacity() / K);
1191   }
1192 }
1193 
1194 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1195  private:
1196   bool _full;
1197  public:
1198   void do_generation(Generation* gen) {
1199     gen->gc_prologue(_full);
1200   }
1201   GenGCPrologueClosure(bool full) : _full(full) {};
1202 };
1203 
1204 void GenCollectedHeap::gc_prologue(bool full) {
1205   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1206 
1207   always_do_update_barrier = false;
1208   // Fill TLAB's and such
1209   CollectedHeap::accumulate_statistics_all_tlabs();
1210   ensure_parsability(true);   // retire TLABs
1211 
1212   // Walk generations
1213   GenGCPrologueClosure blk(full);
1214   generation_iterate(&blk, false);  // not old-to-young.
1215 };
1216 
1217 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1218  private:
1219   bool _full;
1220  public:
1221   void do_generation(Generation* gen) {
1222     gen->gc_epilogue(_full);
1223   }
1224   GenGCEpilogueClosure(bool full) : _full(full) {};
1225 };
1226 
1227 void GenCollectedHeap::gc_epilogue(bool full) {
1228 #ifdef COMPILER2
1229   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1230   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1231   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1232 #endif /* COMPILER2 */
1233 
1234   resize_all_tlabs();
1235 
1236   GenGCEpilogueClosure blk(full);
1237   generation_iterate(&blk, false);  // not old-to-young.
1238 
1239   if (!CleanChunkPoolAsync) {
1240     Chunk::clean_chunk_pool();
1241   }
1242 
1243   MetaspaceCounters::update_performance_counters();
1244   CompressedClassSpaceCounters::update_performance_counters();
1245 
1246   always_do_update_barrier = UseConcMarkSweepGC;
1247 };
1248 
1249 #ifndef PRODUCT
1250 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1251  private:
1252  public:
1253   void do_generation(Generation* gen) {
1254     gen->record_spaces_top();
1255   }
1256 };
1257 
1258 void GenCollectedHeap::record_gen_tops_before_GC() {
1259   if (ZapUnusedHeapArea) {
1260     GenGCSaveTopsBeforeGCClosure blk;
1261     generation_iterate(&blk, false);  // not old-to-young.
1262   }
1263 }
1264 #endif  // not PRODUCT
1265 
1266 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1267  public:
1268   void do_generation(Generation* gen) {
1269     gen->ensure_parsability();
1270   }
1271 };
1272 
1273 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1274   CollectedHeap::ensure_parsability(retire_tlabs);
1275   GenEnsureParsabilityClosure ep_cl;
1276   generation_iterate(&ep_cl, false);
1277 }
1278 
1279 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1280                                               oop obj,
1281                                               size_t obj_size) {
1282   guarantee(old_gen == _old_gen, "We only get here with an old generation");
1283   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1284   HeapWord* result = NULL;
1285 
1286   result = old_gen->expand_and_allocate(obj_size, false);
1287 
1288   if (result != NULL) {
1289     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1290   }
1291   return oop(result);
1292 }
1293 
1294 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1295   jlong _time;   // in ms
1296   jlong _now;    // in ms
1297 
1298  public:
1299   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1300 
1301   jlong time() { return _time; }
1302 
1303   void do_generation(Generation* gen) {
1304     _time = MIN2(_time, gen->time_of_last_gc(_now));
1305   }
1306 };
1307 
1308 jlong GenCollectedHeap::millis_since_last_gc() {
1309   // We need a monotonically non-decreasing time in ms but
1310   // os::javaTimeMillis() does not guarantee monotonicity.
1311   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1312   GenTimeOfLastGCClosure tolgc_cl(now);
1313   // iterate over generations getting the oldest
1314   // time that a generation was collected
1315   generation_iterate(&tolgc_cl, false);
1316 
1317   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1318   // provided the underlying platform provides such a time source
1319   // (and it is bug free). So we still have to guard against getting
1320   // back a time later than 'now'.
1321   jlong retVal = now - tolgc_cl.time();
1322   if (retVal < 0) {
1323     NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1324     return 0;
1325   }
1326   return retVal;
1327 }