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 FlexibleWorkGang("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, 0, 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, 1, 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 // Save the "used_region" for generations level and lower.
 206 void GenCollectedHeap::save_used_regions(int level) {
 207   assert(level == 0 || level == 1, "Illegal level parameter");
 208   if (level == 1) {
 209     _old_gen->save_used_region();
 210   }
 211   _young_gen->save_used_region();
 212 }
 213 
 214 size_t GenCollectedHeap::max_capacity() const {
 215   return _young_gen->max_capacity() + _old_gen->max_capacity();
 216 }
 217 
 218 // Update the _full_collections_completed counter
 219 // at the end of a stop-world full GC.
 220 unsigned int GenCollectedHeap::update_full_collections_completed() {
 221   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 222   assert(_full_collections_completed <= _total_full_collections,
 223          "Can't complete more collections than were started");
 224   _full_collections_completed = _total_full_collections;
 225   ml.notify_all();
 226   return _full_collections_completed;
 227 }
 228 
 229 // Update the _full_collections_completed counter, as appropriate,
 230 // at the end of a concurrent GC cycle. Note the conditional update
 231 // below to allow this method to be called by a concurrent collector
 232 // without synchronizing in any manner with the VM thread (which
 233 // may already have initiated a STW full collection "concurrently").
 234 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
 235   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 236   assert((_full_collections_completed <= _total_full_collections) &&
 237          (count <= _total_full_collections),
 238          "Can't complete more collections than were started");
 239   if (count > _full_collections_completed) {
 240     _full_collections_completed = count;
 241     ml.notify_all();
 242   }
 243   return _full_collections_completed;
 244 }
 245 
 246 
 247 #ifndef PRODUCT
 248 // Override of memory state checking method in CollectedHeap:
 249 // Some collectors (CMS for example) can't have badHeapWordVal written
 250 // in the first two words of an object. (For instance , in the case of
 251 // CMS these words hold state used to synchronize between certain
 252 // (concurrent) GC steps and direct allocating mutators.)
 253 // The skip_header_HeapWords() method below, allows us to skip
 254 // over the requisite number of HeapWord's. Note that (for
 255 // generational collectors) this means that those many words are
 256 // skipped in each object, irrespective of the generation in which
 257 // that object lives. The resultant loss of precision seems to be
 258 // harmless and the pain of avoiding that imprecision appears somewhat
 259 // higher than we are prepared to pay for such rudimentary debugging
 260 // support.
 261 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
 262                                                          size_t size) {
 263   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 264     // We are asked to check a size in HeapWords,
 265     // but the memory is mangled in juint words.
 266     juint* start = (juint*) (addr + skip_header_HeapWords());
 267     juint* end   = (juint*) (addr + size);
 268     for (juint* slot = start; slot < end; slot += 1) {
 269       assert(*slot == badHeapWordVal,
 270              "Found non badHeapWordValue in pre-allocation check");
 271     }
 272   }
 273 }
 274 #endif
 275 
 276 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
 277                                                bool is_tlab,
 278                                                bool first_only) {
 279   HeapWord* res = NULL;
 280 
 281   if (_young_gen->should_allocate(size, is_tlab)) {
 282     res = _young_gen->allocate(size, is_tlab);
 283     if (res != NULL || first_only) {
 284       return res;
 285     }
 286   }
 287 
 288   if (_old_gen->should_allocate(size, is_tlab)) {
 289     res = _old_gen->allocate(size, is_tlab);
 290   }
 291 
 292   return res;
 293 }
 294 
 295 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
 296                                          bool* gc_overhead_limit_was_exceeded) {
 297   return collector_policy()->mem_allocate_work(size,
 298                                                false /* is_tlab */,
 299                                                gc_overhead_limit_was_exceeded);
 300 }
 301 
 302 bool GenCollectedHeap::must_clear_all_soft_refs() {
 303   return _gc_cause == GCCause::_last_ditch_collection;
 304 }
 305 
 306 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
 307   if (!UseConcMarkSweepGC) {
 308     return false;
 309   }
 310 
 311   switch (cause) {
 312     case GCCause::_gc_locker:           return GCLockerInvokesConcurrent;
 313     case GCCause::_java_lang_system_gc:
 314     case GCCause::_dcmd_gc_run:         return ExplicitGCInvokesConcurrent;
 315     default:                            return false;
 316   }
 317 }
 318 
 319 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
 320                                           bool is_tlab, bool run_verification, bool clear_soft_refs,
 321                                           bool restore_marks_for_biased_locking) {
 322   // Timer for individual generations. Last argument is false: no CR
 323   // FIXME: We should try to start the timing earlier to cover more of the GC pause
 324   // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 325   // so we can assume here that the next GC id is what we want.
 326   GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
 327   TraceCollectorStats tcs(gen->counters());
 328   TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
 329 
 330   size_t prev_used = gen->used();
 331   gen->stat_record()->invocations++;
 332   gen->stat_record()->accumulated_time.start();
 333 
 334   // Must be done anew before each collection because
 335   // a previous collection will do mangling and will
 336   // change top of some spaces.
 337   record_gen_tops_before_GC();
 338 
 339   if (PrintGC && Verbose) {
 340     gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
 341                         gen->level(),
 342                         gen->stat_record()->invocations,
 343                         size * HeapWordSize);
 344   }
 345 
 346   if (run_verification && VerifyBeforeGC) {
 347     HandleMark hm;  // Discard invalid handles created during verification
 348     Universe::verify(" VerifyBeforeGC:");
 349   }
 350   COMPILER2_PRESENT(DerivedPointerTable::clear());
 351 
 352   if (restore_marks_for_biased_locking) {
 353     // We perform this mark word preservation work lazily
 354     // because it's only at this point that we know whether we
 355     // absolutely have to do it; we want to avoid doing it for
 356     // scavenge-only collections where it's unnecessary
 357     BiasedLocking::preserve_marks();
 358   }
 359 
 360   // Do collection work
 361   {
 362     // Note on ref discovery: For what appear to be historical reasons,
 363     // GCH enables and disabled (by enqueing) refs discovery.
 364     // In the future this should be moved into the generation's
 365     // collect method so that ref discovery and enqueueing concerns
 366     // are local to a generation. The collect method could return
 367     // an appropriate indication in the case that notification on
 368     // the ref lock was needed. This will make the treatment of
 369     // weak refs more uniform (and indeed remove such concerns
 370     // from GCH). XXX
 371 
 372     HandleMark hm;  // Discard invalid handles created during gc
 373     save_marks();   // save marks for all gens
 374     // We want to discover references, but not process them yet.
 375     // This mode is disabled in process_discovered_references if the
 376     // generation does some collection work, or in
 377     // enqueue_discovered_references if the generation returns
 378     // without doing any work.
 379     ReferenceProcessor* rp = gen->ref_processor();
 380     // If the discovery of ("weak") refs in this generation is
 381     // atomic wrt other collectors in this configuration, we
 382     // are guaranteed to have empty discovered ref lists.
 383     if (rp->discovery_is_atomic()) {
 384       rp->enable_discovery();
 385       rp->setup_policy(clear_soft_refs);
 386     } else {
 387       // collect() below will enable discovery as appropriate
 388     }
 389     gen->collect(full, clear_soft_refs, size, is_tlab);
 390     if (!rp->enqueuing_is_done()) {
 391       rp->enqueue_discovered_references();
 392     } else {
 393       rp->set_enqueuing_is_done(false);
 394     }
 395     rp->verify_no_references_recorded();
 396   }
 397 
 398   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 399 
 400   gen->stat_record()->accumulated_time.stop();
 401 
 402   update_gc_stats(gen->level(), full);
 403 
 404   if (run_verification && VerifyAfterGC) {
 405     HandleMark hm;  // Discard invalid handles created during verification
 406     Universe::verify(" VerifyAfterGC:");
 407   }
 408 
 409   if (PrintGCDetails) {
 410     gclog_or_tty->print(":");
 411     gen->print_heap_change(prev_used);
 412   }
 413 }
 414 
 415 void GenCollectedHeap::do_collection(bool   full,
 416                                      bool   clear_all_soft_refs,
 417                                      size_t size,
 418                                      bool   is_tlab,
 419                                      int    max_level) {
 420   ResourceMark rm;
 421   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 422 
 423   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 424   assert(my_thread->is_VM_thread() ||
 425          my_thread->is_ConcurrentGC_thread(),
 426          "incorrect thread type capability");
 427   assert(Heap_lock->is_locked(),
 428          "the requesting thread should have the Heap_lock");
 429   guarantee(!is_gc_active(), "collection is not reentrant");
 430 
 431   if (GC_locker::check_active_before_gc()) {
 432     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 433   }
 434 
 435   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 436                           collector_policy()->should_clear_all_soft_refs();
 437 
 438   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 439 
 440   const size_t metadata_prev_used = MetaspaceAux::used_bytes();
 441 
 442   print_heap_before_gc();
 443 
 444   {
 445     FlagSetting fl(_is_gc_active, true);
 446 
 447     bool complete = full && (max_level == 1 /* old */);
 448     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 449     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 450     // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 451     // so we can assume here that the next GC id is what we want.
 452     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
 453 
 454     gc_prologue(complete);
 455     increment_total_collections(complete);
 456 
 457     size_t gch_prev_used = used();
 458     bool run_verification = total_collections() >= VerifyGCStartAt;
 459 
 460     bool prepared_for_verification = false;
 461     int max_level_collected = 0;
 462     bool old_collects_young = (max_level == 1) &&
 463                               full &&
 464                               _old_gen->full_collects_younger_generations();
 465     if (!old_collects_young &&
 466         _young_gen->should_collect(full, size, is_tlab)) {
 467       if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
 468         prepare_for_verify();
 469         prepared_for_verification = true;
 470       }
 471 
 472       assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
 473       collect_generation(_young_gen,
 474                          full,
 475                          size,
 476                          is_tlab,
 477                          run_verification && VerifyGCLevel <= 0,
 478                          do_clear_all_soft_refs,
 479                          false);
 480 
 481       if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
 482           size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
 483         // Allocation request was met by young GC.
 484         size = 0;
 485       }
 486     }
 487 
 488     bool must_restore_marks_for_biased_locking = false;
 489 
 490     if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
 491       if (!complete) {
 492         // The full_collections increment was missed above.
 493         increment_total_full_collections();
 494       }
 495 
 496       pre_full_gc_dump(NULL);    // do any pre full gc dumps
 497 
 498       if (!prepared_for_verification && run_verification &&
 499           VerifyGCLevel <= 1 && VerifyBeforeGC) {
 500         prepare_for_verify();
 501       }
 502 
 503       assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
 504       collect_generation(_old_gen,
 505                          full,
 506                          size,
 507                          is_tlab,
 508                          run_verification && VerifyGCLevel <= 1,
 509                          do_clear_all_soft_refs,
 510                          true);
 511 
 512       must_restore_marks_for_biased_locking = true;
 513       max_level_collected = 1;
 514     }
 515 
 516     // Update "complete" boolean wrt what actually transpired --
 517     // for instance, a promotion failure could have led to
 518     // a whole heap collection.
 519     complete = complete || (max_level_collected == 1 /* old */);
 520 
 521     if (complete) { // We did a "major" collection
 522       // FIXME: See comment at pre_full_gc_dump call
 523       post_full_gc_dump(NULL);   // do any post full gc dumps
 524     }
 525 
 526     if (PrintGCDetails) {
 527       print_heap_change(gch_prev_used);
 528 
 529       // Print metaspace info for full GC with PrintGCDetails flag.
 530       if (complete) {
 531         MetaspaceAux::print_metaspace_change(metadata_prev_used);
 532       }
 533     }
 534 
 535     // Adjust generation sizes.
 536     if (max_level_collected == 1 /* old */) {
 537       _old_gen->compute_new_size();
 538     }
 539     _young_gen->compute_new_size();
 540 
 541     if (complete) {
 542       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 543       ClassLoaderDataGraph::purge();
 544       MetaspaceAux::verify_metrics();
 545       // Resize the metaspace capacity after full collections
 546       MetaspaceGC::compute_new_size();
 547       update_full_collections_completed();
 548     }
 549 
 550     // Track memory usage and detect low memory after GC finishes
 551     MemoryService::track_memory_usage();
 552 
 553     gc_epilogue(complete);
 554 
 555     if (must_restore_marks_for_biased_locking) {
 556       BiasedLocking::restore_marks();
 557     }
 558   }
 559 
 560   print_heap_after_gc();
 561 
 562 #ifdef TRACESPINNING
 563   ParallelTaskTerminator::print_termination_counts();
 564 #endif
 565 }
 566 
 567 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 568   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 569 }
 570 
 571 #ifdef ASSERT
 572 class AssertNonScavengableClosure: public OopClosure {
 573 public:
 574   virtual void do_oop(oop* p) {
 575     assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
 576       "Referent should not be scavengable.");  }
 577   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 578 };
 579 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 580 #endif
 581 
 582 void GenCollectedHeap::process_roots(StrongRootsScope* scope,
 583                                      ScanningOption so,
 584                                      OopClosure* strong_roots,
 585                                      OopClosure* weak_roots,
 586                                      CLDClosure* strong_cld_closure,
 587                                      CLDClosure* weak_cld_closure,
 588                                      CodeBlobClosure* code_roots) {
 589   // General roots.
 590   assert(Threads::thread_claim_parity() != 0, "must have called prologue code");
 591   assert(code_roots != NULL, "code root closure should always be set");
 592   // _n_termination for _process_strong_tasks should be set up stream
 593   // in a method not running in a GC worker.  Otherwise the GC worker
 594   // could be trying to change the termination condition while the task
 595   // is executing in another GC worker.
 596 
 597   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ClassLoaderDataGraph_oops_do)) {
 598     ClassLoaderDataGraph::roots_cld_do(strong_cld_closure, weak_cld_closure);
 599   }
 600 
 601   // Some CLDs contained in the thread frames should be considered strong.
 602   // Don't process them if they will be processed during the ClassLoaderDataGraph phase.
 603   CLDClosure* roots_from_clds_p = (strong_cld_closure != weak_cld_closure) ? strong_cld_closure : NULL;
 604   // Only process code roots from thread stacks if we aren't visiting the entire CodeCache anyway
 605   CodeBlobClosure* roots_from_code_p = (so & SO_AllCodeCache) ? NULL : code_roots;
 606 
 607   bool is_par = scope->n_threads() > 1;
 608   Threads::possibly_parallel_oops_do(is_par, strong_roots, roots_from_clds_p, roots_from_code_p);
 609 
 610   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Universe_oops_do)) {
 611     Universe::oops_do(strong_roots);
 612   }
 613   // Global (strong) JNI handles
 614   if (!_process_strong_tasks->is_task_claimed(GCH_PS_JNIHandles_oops_do)) {
 615     JNIHandles::oops_do(strong_roots);
 616   }
 617 
 618   if (!_process_strong_tasks->is_task_claimed(GCH_PS_ObjectSynchronizer_oops_do)) {
 619     ObjectSynchronizer::oops_do(strong_roots);
 620   }
 621   if (!_process_strong_tasks->is_task_claimed(GCH_PS_FlatProfiler_oops_do)) {
 622     FlatProfiler::oops_do(strong_roots);
 623   }
 624   if (!_process_strong_tasks->is_task_claimed(GCH_PS_Management_oops_do)) {
 625     Management::oops_do(strong_roots);
 626   }
 627   if (!_process_strong_tasks->is_task_claimed(GCH_PS_jvmti_oops_do)) {
 628     JvmtiExport::oops_do(strong_roots);
 629   }
 630 
 631   if (!_process_strong_tasks->is_task_claimed(GCH_PS_SystemDictionary_oops_do)) {
 632     SystemDictionary::roots_oops_do(strong_roots, weak_roots);
 633   }
 634 
 635   // All threads execute the following. A specific chunk of buckets
 636   // from the StringTable are the individual tasks.
 637   if (weak_roots != NULL) {
 638     if (is_par) {
 639       StringTable::possibly_parallel_oops_do(weak_roots);
 640     } else {
 641       StringTable::oops_do(weak_roots);
 642     }
 643   }
 644 
 645   if (!_process_strong_tasks->is_task_claimed(GCH_PS_CodeCache_oops_do)) {
 646     if (so & SO_ScavengeCodeCache) {
 647       assert(code_roots != NULL, "must supply closure for code cache");
 648 
 649       // We only visit parts of the CodeCache when scavenging.
 650       CodeCache::scavenge_root_nmethods_do(code_roots);
 651     }
 652     if (so & SO_AllCodeCache) {
 653       assert(code_roots != NULL, "must supply closure for code cache");
 654 
 655       // CMSCollector uses this to do intermediate-strength collections.
 656       // We scan the entire code cache, since CodeCache::do_unloading is not called.
 657       CodeCache::blobs_do(code_roots);
 658     }
 659     // Verify that the code cache contents are not subject to
 660     // movement by a scavenging collection.
 661     DEBUG_ONLY(CodeBlobToOopClosure assert_code_is_non_scavengable(&assert_is_non_scavengable_closure, !CodeBlobToOopClosure::FixRelocations));
 662     DEBUG_ONLY(CodeCache::asserted_non_scavengable_nmethods_do(&assert_code_is_non_scavengable));
 663   }
 664 
 665 }
 666 
 667 void GenCollectedHeap::gen_process_roots(StrongRootsScope* scope,
 668                                          int level,
 669                                          bool younger_gens_as_roots,
 670                                          ScanningOption so,
 671                                          bool only_strong_roots,
 672                                          OopsInGenClosure* not_older_gens,
 673                                          OopsInGenClosure* older_gens,
 674                                          CLDClosure* cld_closure) {
 675   const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
 676 
 677   bool is_moving_collection = false;
 678   if (level == 0 || is_adjust_phase) {
 679     // young collections are always moving
 680     is_moving_collection = true;
 681   }
 682 
 683   MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
 684   OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
 685   CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
 686 
 687   process_roots(scope, so,
 688                 not_older_gens, weak_roots,
 689                 cld_closure, weak_cld_closure,
 690                 &mark_code_closure);
 691 
 692   if (younger_gens_as_roots) {
 693     if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 694       if (level == 1) {
 695         not_older_gens->set_generation(_young_gen);
 696         _young_gen->oop_iterate(not_older_gens);
 697       }
 698       not_older_gens->reset_generation();
 699     }
 700   }
 701   // When collection is parallel, all threads get to cooperate to do
 702   // older-gen scanning.
 703   if (level == 0) {
 704     older_gens->set_generation(_old_gen);
 705     rem_set()->younger_refs_iterate(_old_gen, older_gens, scope->n_threads());
 706     older_gens->reset_generation();
 707   }
 708 
 709   _process_strong_tasks->all_tasks_completed(scope->n_threads());
 710 }
 711 
 712 
 713 class AlwaysTrueClosure: public BoolObjectClosure {
 714 public:
 715   bool do_object_b(oop p) { return true; }
 716 };
 717 static AlwaysTrueClosure always_true;
 718 
 719 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
 720   JNIHandles::weak_oops_do(&always_true, root_closure);
 721   _young_gen->ref_processor()->weak_oops_do(root_closure);
 722   _old_gen->ref_processor()->weak_oops_do(root_closure);
 723 }
 724 
 725 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 726 void GenCollectedHeap::                                                 \
 727 oop_since_save_marks_iterate(int level,                                 \
 728                              OopClosureType* cur,                       \
 729                              OopClosureType* older) {                   \
 730   if (level == 0) {                                                     \
 731     _young_gen->oop_since_save_marks_iterate##nv_suffix(cur);           \
 732     _old_gen->oop_since_save_marks_iterate##nv_suffix(older);           \
 733   } else {                                                              \
 734     _old_gen->oop_since_save_marks_iterate##nv_suffix(cur);             \
 735   }                                                                     \
 736 }
 737 
 738 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 739 
 740 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 741 
 742 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
 743   if (level == 0 && !_young_gen->no_allocs_since_save_marks()) {
 744     return false;
 745   }
 746   return _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, 0 /* young */);
 774   } else {
 775 #ifdef ASSERT
 776   if (cause == GCCause::_scavenge_alot) {
 777     // minor collection only
 778     collect(cause, 0 /* young */);
 779   } else {
 780     // Stop-the-world full collection
 781     collect(cause, 1 /* old */);
 782   }
 783 #else
 784     // Stop-the-world full collection
 785     collect(cause, 1 /* old */);
 786 #endif
 787   }
 788 }
 789 
 790 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
 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_level);
 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, 1 /* old */);
 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, int max_level) {
 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_level);
 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, 1 /* old */);
 857 }
 858 
 859 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 860                                           int max_level) {
 861   int local_max_level;
 862   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 863       gc_cause() == GCCause::_gc_locker) {
 864     local_max_level = 0;
 865   } else {
 866     local_max_level = max_level;
 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_max_level      /* max_level */);
 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_max_level == 0 && 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                   1  /* old */         /* max_level */);
 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(int level) const {
1112   if (level == 0) {
1113     return _young_gen->gc_stats();
1114   } else {
1115     return _old_gen->gc_stats();
1116   }
1117 }
1118 
1119 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1120   if (!silent) {
1121     gclog_or_tty->print("%s", _old_gen->name());
1122     gclog_or_tty->print(" ");
1123   }
1124   _old_gen->verify();
1125 
1126   if (!silent) {
1127     gclog_or_tty->print("%s", _young_gen->name());
1128     gclog_or_tty->print(" ");
1129   }
1130   _young_gen->verify();
1131 
1132   if (!silent) {
1133     gclog_or_tty->print("remset ");
1134   }
1135   rem_set()->verify();
1136 }
1137 
1138 void GenCollectedHeap::print_on(outputStream* st) const {
1139   _young_gen->print_on(st);
1140   _old_gen->print_on(st);
1141   MetaspaceAux::print_on(st);
1142 }
1143 
1144 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1145   if (workers() != NULL) {
1146     workers()->threads_do(tc);
1147   }
1148 #if INCLUDE_ALL_GCS
1149   if (UseConcMarkSweepGC) {
1150     ConcurrentMarkSweepThread::threads_do(tc);
1151   }
1152 #endif // INCLUDE_ALL_GCS
1153 }
1154 
1155 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1156 #if INCLUDE_ALL_GCS
1157   if (UseConcMarkSweepGC) {
1158     workers()->print_worker_threads_on(st);
1159     ConcurrentMarkSweepThread::print_all_on(st);
1160   }
1161 #endif // INCLUDE_ALL_GCS
1162 }
1163 
1164 void GenCollectedHeap::print_on_error(outputStream* st) const {
1165   this->CollectedHeap::print_on_error(st);
1166 
1167 #if INCLUDE_ALL_GCS
1168   if (UseConcMarkSweepGC) {
1169     st->cr();
1170     CMSCollector::print_on_error(st);
1171   }
1172 #endif // INCLUDE_ALL_GCS
1173 }
1174 
1175 void GenCollectedHeap::print_tracing_info() const {
1176   if (TraceYoungGenTime) {
1177     _young_gen->print_summary_info();
1178   }
1179   if (TraceOldGenTime) {
1180     _old_gen->print_summary_info();
1181   }
1182 }
1183 
1184 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1185   if (PrintGCDetails && Verbose) {
1186     gclog_or_tty->print(" "  SIZE_FORMAT
1187                         "->" SIZE_FORMAT
1188                         "("  SIZE_FORMAT ")",
1189                         prev_used, used(), capacity());
1190   } else {
1191     gclog_or_tty->print(" "  SIZE_FORMAT "K"
1192                         "->" SIZE_FORMAT "K"
1193                         "("  SIZE_FORMAT "K)",
1194                         prev_used / K, used() / K, capacity() / K);
1195   }
1196 }
1197 
1198 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1199  private:
1200   bool _full;
1201  public:
1202   void do_generation(Generation* gen) {
1203     gen->gc_prologue(_full);
1204   }
1205   GenGCPrologueClosure(bool full) : _full(full) {};
1206 };
1207 
1208 void GenCollectedHeap::gc_prologue(bool full) {
1209   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1210 
1211   always_do_update_barrier = false;
1212   // Fill TLAB's and such
1213   CollectedHeap::accumulate_statistics_all_tlabs();
1214   ensure_parsability(true);   // retire TLABs
1215 
1216   // Walk generations
1217   GenGCPrologueClosure blk(full);
1218   generation_iterate(&blk, false);  // not old-to-young.
1219 };
1220 
1221 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1222  private:
1223   bool _full;
1224  public:
1225   void do_generation(Generation* gen) {
1226     gen->gc_epilogue(_full);
1227   }
1228   GenGCEpilogueClosure(bool full) : _full(full) {};
1229 };
1230 
1231 void GenCollectedHeap::gc_epilogue(bool full) {
1232 #ifdef COMPILER2
1233   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1234   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1235   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1236 #endif /* COMPILER2 */
1237 
1238   resize_all_tlabs();
1239 
1240   GenGCEpilogueClosure blk(full);
1241   generation_iterate(&blk, false);  // not old-to-young.
1242 
1243   if (!CleanChunkPoolAsync) {
1244     Chunk::clean_chunk_pool();
1245   }
1246 
1247   MetaspaceCounters::update_performance_counters();
1248   CompressedClassSpaceCounters::update_performance_counters();
1249 
1250   always_do_update_barrier = UseConcMarkSweepGC;
1251 };
1252 
1253 #ifndef PRODUCT
1254 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1255  private:
1256  public:
1257   void do_generation(Generation* gen) {
1258     gen->record_spaces_top();
1259   }
1260 };
1261 
1262 void GenCollectedHeap::record_gen_tops_before_GC() {
1263   if (ZapUnusedHeapArea) {
1264     GenGCSaveTopsBeforeGCClosure blk;
1265     generation_iterate(&blk, false);  // not old-to-young.
1266   }
1267 }
1268 #endif  // not PRODUCT
1269 
1270 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1271  public:
1272   void do_generation(Generation* gen) {
1273     gen->ensure_parsability();
1274   }
1275 };
1276 
1277 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1278   CollectedHeap::ensure_parsability(retire_tlabs);
1279   GenEnsureParsabilityClosure ep_cl;
1280   generation_iterate(&ep_cl, false);
1281 }
1282 
1283 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1284                                               oop obj,
1285                                               size_t obj_size) {
1286   guarantee(old_gen->level() == 1, "We only get here with an old generation");
1287   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1288   HeapWord* result = NULL;
1289 
1290   result = old_gen->expand_and_allocate(obj_size, false);
1291 
1292   if (result != NULL) {
1293     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1294   }
1295   return oop(result);
1296 }
1297 
1298 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1299   jlong _time;   // in ms
1300   jlong _now;    // in ms
1301 
1302  public:
1303   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1304 
1305   jlong time() { return _time; }
1306 
1307   void do_generation(Generation* gen) {
1308     _time = MIN2(_time, gen->time_of_last_gc(_now));
1309   }
1310 };
1311 
1312 jlong GenCollectedHeap::millis_since_last_gc() {
1313   // We need a monotonically non-decreasing time in ms but
1314   // os::javaTimeMillis() does not guarantee monotonicity.
1315   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1316   GenTimeOfLastGCClosure tolgc_cl(now);
1317   // iterate over generations getting the oldest
1318   // time that a generation was collected
1319   generation_iterate(&tolgc_cl, false);
1320 
1321   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1322   // provided the underlying platform provides such a time source
1323   // (and it is bug free). So we still have to guard against getting
1324   // back a time later than 'now'.
1325   jlong retVal = now - tolgc_cl.time();
1326   if (retVal < 0) {
1327     NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1328     return 0;
1329   }
1330   return retVal;
1331 }