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_implementation/shared/collectorCounters.hpp"
  32 #include "gc_implementation/shared/gcTrace.hpp"
  33 #include "gc_implementation/shared/gcTraceTime.hpp"
  34 #include "gc_implementation/shared/vmGCOperations.hpp"
  35 #include "gc_interface/collectedHeap.inline.hpp"
  36 #include "memory/filemap.hpp"
  37 #include "memory/gcLocker.inline.hpp"
  38 #include "memory/genCollectedHeap.hpp"
  39 #include "memory/genOopClosures.inline.hpp"
  40 #include "memory/generationSpec.hpp"
  41 #include "memory/resourceArea.hpp"
  42 #include "memory/sharedHeap.hpp"
  43 #include "memory/space.hpp"
  44 #include "oops/oop.inline.hpp"
  45 #include "runtime/biasedLocking.hpp"
  46 #include "runtime/fprofiler.hpp"
  47 #include "runtime/handles.hpp"
  48 #include "runtime/handles.inline.hpp"
  49 #include "runtime/java.hpp"
  50 #include "runtime/vmThread.hpp"
  51 #include "services/management.hpp"
  52 #include "services/memoryService.hpp"
  53 #include "utilities/vmError.hpp"
  54 #include "utilities/workgroup.hpp"
  55 #include "utilities/macros.hpp"
  56 #if INCLUDE_ALL_GCS
  57 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"
  58 #include "gc_implementation/concurrentMarkSweep/vmCMSOperations.hpp"
  59 #endif // INCLUDE_ALL_GCS
  60 
  61 GenCollectedHeap* GenCollectedHeap::_gch;
  62 NOT_PRODUCT(size_t GenCollectedHeap::_skip_header_HeapWords = 0;)
  63 
  64 // The set of potentially parallel tasks in root scanning.
  65 enum GCH_strong_roots_tasks {
  66   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   SharedHeap(),
  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 }
  89 
  90 jint GenCollectedHeap::initialize() {
  91   CollectedHeap::pre_initialize();
  92 
  93   _n_gens = gen_policy()->number_of_generations();
  94   assert(_n_gens == 2, "There is no support for more than two generations");
  95 
  96   // While there are no constraints in the GC code that HeapWordSize
  97   // be any particular value, there are multiple other areas in the
  98   // system which believe this to be true (e.g. oop->object_size in some
  99   // cases incorrectly returns the size in wordSize units rather than
 100   // HeapWordSize).
 101   guarantee(HeapWordSize == wordSize, "HeapWordSize must equal wordSize");
 102 
 103   // Allocate space for the heap.
 104 
 105   char* heap_address;
 106   ReservedSpace heap_rs;
 107 
 108   size_t heap_alignment = collector_policy()->heap_alignment();
 109 
 110   heap_address = allocate(heap_alignment, &heap_rs);
 111 
 112   if (!heap_rs.is_reserved()) {
 113     vm_shutdown_during_initialization(
 114       "Could not reserve enough space for object heap");
 115     return JNI_ENOMEM;
 116   }
 117 
 118   initialize_reserved_region((HeapWord*)heap_rs.base(), (HeapWord*)(heap_rs.base() + heap_rs.size()));
 119 
 120   _rem_set = collector_policy()->create_rem_set(reserved_region());
 121   _barrier_set = rem_set()->bs();
 122   oopDesc::set_bs(_barrier_set);
 123 
 124   _gch = this;
 125 
 126   ReservedSpace young_rs = heap_rs.first_part(gen_policy()->young_gen_spec()->max_size(), false, false);
 127   _young_gen = gen_policy()->young_gen_spec()->init(young_rs, 0, rem_set());
 128   heap_rs = heap_rs.last_part(gen_policy()->young_gen_spec()->max_size());
 129 
 130   ReservedSpace old_rs = heap_rs.first_part(gen_policy()->old_gen_spec()->max_size(), false, false);
 131   _old_gen = gen_policy()->old_gen_spec()->init(old_rs, 1, rem_set());
 132   clear_incremental_collection_failed();
 133 
 134 #if INCLUDE_ALL_GCS
 135   // If we are running CMS, create the collector responsible
 136   // for collecting the CMS generations.
 137   if (collector_policy()->is_concurrent_mark_sweep_policy()) {
 138     bool success = create_cms_collector();
 139     if (!success) return JNI_ENOMEM;
 140   }
 141 #endif // INCLUDE_ALL_GCS
 142 
 143   return JNI_OK;
 144 }
 145 
 146 char* GenCollectedHeap::allocate(size_t alignment,
 147                                  ReservedSpace* heap_rs){
 148   // Now figure out the total size.
 149   const size_t pageSize = UseLargePages ? os::large_page_size() : os::vm_page_size();
 150   assert(alignment % pageSize == 0, "Must be");
 151 
 152   GenerationSpec* young_spec = gen_policy()->young_gen_spec();
 153   GenerationSpec* old_spec = gen_policy()->old_gen_spec();
 154 
 155   // Check for overflow.
 156   size_t total_reserved = young_spec->max_size() + old_spec->max_size();
 157   if (total_reserved < young_spec->max_size()) {
 158     vm_exit_during_initialization("The size of the object heap + VM data exceeds "
 159                                   "the maximum representable size");
 160   }
 161   assert(total_reserved % alignment == 0,
 162          err_msg("Gen size; total_reserved=" SIZE_FORMAT ", alignment="
 163                  SIZE_FORMAT, total_reserved, alignment));
 164 
 165   *heap_rs = Universe::reserve_heap(total_reserved, alignment);
 166   return heap_rs->base();
 167 }
 168 
 169 void GenCollectedHeap::post_initialize() {
 170   CollectedHeap::post_initialize();
 171   ref_processing_init();
 172   GenCollectorPolicy *policy = (GenCollectorPolicy *)collector_policy();
 173   guarantee(policy->is_generation_policy(), "Illegal policy type");
 174   assert((_young_gen->kind() == Generation::DefNew) ||
 175          (_young_gen->kind() == Generation::ParNew),
 176     "Wrong youngest generation type");
 177   DefNewGeneration* def_new_gen = (DefNewGeneration*)_young_gen;
 178 
 179   assert(_old_gen->kind() == Generation::ConcurrentMarkSweep ||
 180          _old_gen->kind() == Generation::MarkSweepCompact,
 181     "Wrong generation kind");
 182 
 183   policy->initialize_size_policy(def_new_gen->eden()->capacity(),
 184                                  _old_gen->capacity(),
 185                                  def_new_gen->from()->capacity());
 186   policy->initialize_gc_policy_counters();
 187 }
 188 
 189 void GenCollectedHeap::ref_processing_init() {
 190   _young_gen->ref_processor_init();
 191   _old_gen->ref_processor_init();
 192 }
 193 
 194 size_t GenCollectedHeap::capacity() const {
 195   return _young_gen->capacity() + _old_gen->capacity();
 196 }
 197 
 198 size_t GenCollectedHeap::used() const {
 199   return _young_gen->used() + _old_gen->used();
 200 }
 201 
 202 // Save the "used_region" for generations level and lower.
 203 void GenCollectedHeap::save_used_regions(int level) {
 204   assert(level >= 0, "Illegal level parameter");
 205   assert(level < _n_gens, "Illegal level parameter");
 206   if (level == 1) {
 207     _old_gen->save_used_region();
 208   }
 209   _young_gen->save_used_region();
 210 }
 211 
 212 size_t GenCollectedHeap::max_capacity() const {
 213   return _young_gen->max_capacity() + _old_gen->max_capacity();
 214 }
 215 
 216 // Update the _full_collections_completed counter
 217 // at the end of a stop-world full GC.
 218 unsigned int GenCollectedHeap::update_full_collections_completed() {
 219   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 220   assert(_full_collections_completed <= _total_full_collections,
 221          "Can't complete more collections than were started");
 222   _full_collections_completed = _total_full_collections;
 223   ml.notify_all();
 224   return _full_collections_completed;
 225 }
 226 
 227 // Update the _full_collections_completed counter, as appropriate,
 228 // at the end of a concurrent GC cycle. Note the conditional update
 229 // below to allow this method to be called by a concurrent collector
 230 // without synchronizing in any manner with the VM thread (which
 231 // may already have initiated a STW full collection "concurrently").
 232 unsigned int GenCollectedHeap::update_full_collections_completed(unsigned int count) {
 233   MonitorLockerEx ml(FullGCCount_lock, Mutex::_no_safepoint_check_flag);
 234   assert((_full_collections_completed <= _total_full_collections) &&
 235          (count <= _total_full_collections),
 236          "Can't complete more collections than were started");
 237   if (count > _full_collections_completed) {
 238     _full_collections_completed = count;
 239     ml.notify_all();
 240   }
 241   return _full_collections_completed;
 242 }
 243 
 244 
 245 #ifndef PRODUCT
 246 // Override of memory state checking method in CollectedHeap:
 247 // Some collectors (CMS for example) can't have badHeapWordVal written
 248 // in the first two words of an object. (For instance , in the case of
 249 // CMS these words hold state used to synchronize between certain
 250 // (concurrent) GC steps and direct allocating mutators.)
 251 // The skip_header_HeapWords() method below, allows us to skip
 252 // over the requisite number of HeapWord's. Note that (for
 253 // generational collectors) this means that those many words are
 254 // skipped in each object, irrespective of the generation in which
 255 // that object lives. The resultant loss of precision seems to be
 256 // harmless and the pain of avoiding that imprecision appears somewhat
 257 // higher than we are prepared to pay for such rudimentary debugging
 258 // support.
 259 void GenCollectedHeap::check_for_non_bad_heap_word_value(HeapWord* addr,
 260                                                          size_t size) {
 261   if (CheckMemoryInitialization && ZapUnusedHeapArea) {
 262     // We are asked to check a size in HeapWords,
 263     // but the memory is mangled in juint words.
 264     juint* start = (juint*) (addr + skip_header_HeapWords());
 265     juint* end   = (juint*) (addr + size);
 266     for (juint* slot = start; slot < end; slot += 1) {
 267       assert(*slot == badHeapWordVal,
 268              "Found non badHeapWordValue in pre-allocation check");
 269     }
 270   }
 271 }
 272 #endif
 273 
 274 HeapWord* GenCollectedHeap::attempt_allocation(size_t size,
 275                                                bool is_tlab,
 276                                                bool first_only) {
 277   HeapWord* res = NULL;
 278 
 279   if (_young_gen->should_allocate(size, is_tlab)) {
 280     res = _young_gen->allocate(size, is_tlab);
 281     if (res != NULL || first_only) {
 282       return res;
 283     }
 284   }
 285 
 286   if (_old_gen->should_allocate(size, is_tlab)) {
 287     res = _old_gen->allocate(size, is_tlab);
 288   }
 289 
 290   return res;
 291 }
 292 
 293 HeapWord* GenCollectedHeap::mem_allocate(size_t size,
 294                                          bool* gc_overhead_limit_was_exceeded) {
 295   return collector_policy()->mem_allocate_work(size,
 296                                                false /* is_tlab */,
 297                                                gc_overhead_limit_was_exceeded);
 298 }
 299 
 300 bool GenCollectedHeap::must_clear_all_soft_refs() {
 301   return _gc_cause == GCCause::_last_ditch_collection;
 302 }
 303 
 304 bool GenCollectedHeap::should_do_concurrent_full_gc(GCCause::Cause cause) {
 305   return UseConcMarkSweepGC &&
 306          ((cause == GCCause::_gc_locker && GCLockerInvokesConcurrent) ||
 307           (cause == GCCause::_java_lang_system_gc && ExplicitGCInvokesConcurrent));
 308 }
 309 
 310 void GenCollectedHeap::collect_generation(Generation* gen, bool full, size_t size,
 311                                           bool is_tlab, bool run_verification, bool clear_soft_refs,
 312                                           bool restore_marks_for_biased_locking) {
 313   // Timer for individual generations. Last argument is false: no CR
 314   // FIXME: We should try to start the timing earlier to cover more of the GC pause
 315   // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 316   // so we can assume here that the next GC id is what we want.
 317   GCTraceTime t1(gen->short_name(), PrintGCDetails, false, NULL, GCId::peek());
 318   TraceCollectorStats tcs(gen->counters());
 319   TraceMemoryManagerStats tmms(gen->kind(),gc_cause());
 320 
 321   size_t prev_used = gen->used();
 322   gen->stat_record()->invocations++;
 323   gen->stat_record()->accumulated_time.start();
 324 
 325   // Must be done anew before each collection because
 326   // a previous collection will do mangling and will
 327   // change top of some spaces.
 328   record_gen_tops_before_GC();
 329 
 330   if (PrintGC && Verbose) {
 331     gclog_or_tty->print("level=%d invoke=%d size=" SIZE_FORMAT,
 332                         gen->level(),
 333                         gen->stat_record()->invocations,
 334                         size * HeapWordSize);
 335   }
 336 
 337   if (run_verification && VerifyBeforeGC) {
 338     HandleMark hm;  // Discard invalid handles created during verification
 339     Universe::verify(" VerifyBeforeGC:");
 340   }
 341   COMPILER2_PRESENT(DerivedPointerTable::clear());
 342 
 343   if (restore_marks_for_biased_locking) {
 344     // We perform this mark word preservation work lazily
 345     // because it's only at this point that we know whether we
 346     // absolutely have to do it; we want to avoid doing it for
 347     // scavenge-only collections where it's unnecessary
 348     BiasedLocking::preserve_marks();
 349   }
 350 
 351   // Do collection work
 352   {
 353     // Note on ref discovery: For what appear to be historical reasons,
 354     // GCH enables and disabled (by enqueing) refs discovery.
 355     // In the future this should be moved into the generation's
 356     // collect method so that ref discovery and enqueueing concerns
 357     // are local to a generation. The collect method could return
 358     // an appropriate indication in the case that notification on
 359     // the ref lock was needed. This will make the treatment of
 360     // weak refs more uniform (and indeed remove such concerns
 361     // from GCH). XXX
 362 
 363     HandleMark hm;  // Discard invalid handles created during gc
 364     save_marks();   // save marks for all gens
 365     // We want to discover references, but not process them yet.
 366     // This mode is disabled in process_discovered_references if the
 367     // generation does some collection work, or in
 368     // enqueue_discovered_references if the generation returns
 369     // without doing any work.
 370     ReferenceProcessor* rp = gen->ref_processor();
 371     // If the discovery of ("weak") refs in this generation is
 372     // atomic wrt other collectors in this configuration, we
 373     // are guaranteed to have empty discovered ref lists.
 374     if (rp->discovery_is_atomic()) {
 375       rp->enable_discovery();
 376       rp->setup_policy(clear_soft_refs);
 377     } else {
 378       // collect() below will enable discovery as appropriate
 379     }
 380     gen->collect(full, clear_soft_refs, size, is_tlab);
 381     if (!rp->enqueuing_is_done()) {
 382       rp->enqueue_discovered_references();
 383     } else {
 384       rp->set_enqueuing_is_done(false);
 385     }
 386     rp->verify_no_references_recorded();
 387   }
 388 
 389   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 390 
 391   gen->stat_record()->accumulated_time.stop();
 392 
 393   update_gc_stats(gen->level(), full);
 394 
 395   if (run_verification && VerifyAfterGC) {
 396     HandleMark hm;  // Discard invalid handles created during verification
 397     Universe::verify(" VerifyAfterGC:");
 398   }
 399 
 400   if (PrintGCDetails) {
 401     gclog_or_tty->print(":");
 402     gen->print_heap_change(prev_used);
 403   }
 404 }
 405 
 406 void GenCollectedHeap::do_collection(bool   full,
 407                                      bool   clear_all_soft_refs,
 408                                      size_t size,
 409                                      bool   is_tlab,
 410                                      int    max_level) {
 411   ResourceMark rm;
 412   DEBUG_ONLY(Thread* my_thread = Thread::current();)
 413 
 414   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
 415   assert(my_thread->is_VM_thread() ||
 416          my_thread->is_ConcurrentGC_thread(),
 417          "incorrect thread type capability");
 418   assert(Heap_lock->is_locked(),
 419          "the requesting thread should have the Heap_lock");
 420   guarantee(!is_gc_active(), "collection is not reentrant");
 421   assert(max_level < n_gens(), "sanity check");
 422 
 423   if (GC_locker::check_active_before_gc()) {
 424     return; // GC is disabled (e.g. JNI GetXXXCritical operation)
 425   }
 426 
 427   const bool do_clear_all_soft_refs = clear_all_soft_refs ||
 428                           collector_policy()->should_clear_all_soft_refs();
 429 
 430   ClearedAllSoftRefs casr(do_clear_all_soft_refs, collector_policy());
 431 
 432   const size_t metadata_prev_used = MetaspaceAux::used_bytes();
 433 
 434   print_heap_before_gc();
 435 
 436   {
 437     FlagSetting fl(_is_gc_active, true);
 438 
 439     bool complete = full && (max_level == (n_gens()-1));
 440     const char* gc_cause_prefix = complete ? "Full GC" : "GC";
 441     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
 442     // The PrintGCDetails logging starts before we have incremented the GC id. We will do that later
 443     // so we can assume here that the next GC id is what we want.
 444     GCTraceTime t(GCCauseString(gc_cause_prefix, gc_cause()), PrintGCDetails, false, NULL, GCId::peek());
 445 
 446     gc_prologue(complete);
 447     increment_total_collections(complete);
 448 
 449     size_t gch_prev_used = used();
 450     bool run_verification = total_collections() >= VerifyGCStartAt;
 451 
 452     bool prepared_for_verification = false;
 453     int max_level_collected = 0;
 454     bool old_collects_young = (max_level == 1) &&
 455                               full &&
 456                               _old_gen->full_collects_younger_generations();
 457     if (!old_collects_young &&
 458         _young_gen->should_collect(full, size, is_tlab)) {
 459       if (run_verification && VerifyGCLevel <= 0 && VerifyBeforeGC) {
 460         prepare_for_verify();
 461         prepared_for_verification = true;
 462       }
 463 
 464       assert(!_young_gen->performs_in_place_marking(), "No young generation do in place marking");
 465       collect_generation(_young_gen,
 466                          full,
 467                          size,
 468                          is_tlab,
 469                          run_verification && VerifyGCLevel <= 0,
 470                          do_clear_all_soft_refs,
 471                          false);
 472 
 473       if (size > 0 && (!is_tlab || _young_gen->supports_tlab_allocation()) &&
 474           size * HeapWordSize <= _young_gen->unsafe_max_alloc_nogc()) {
 475         // Allocation request was met by young GC.
 476         size = 0;
 477       }
 478     }
 479 
 480     bool must_restore_marks_for_biased_locking = false;
 481 
 482     if (max_level == 1 && _old_gen->should_collect(full, size, is_tlab)) {
 483       if (!complete) {
 484         // The full_collections increment was missed above.
 485         increment_total_full_collections();
 486       }
 487 
 488       pre_full_gc_dump(NULL);    // do any pre full gc dumps
 489 
 490       if (!prepared_for_verification && run_verification &&
 491           VerifyGCLevel <= 1 && VerifyBeforeGC) {
 492         prepare_for_verify();
 493       }
 494 
 495       assert(_old_gen->performs_in_place_marking(), "All old generations do in place marking");
 496       collect_generation(_old_gen,
 497                          full,
 498                          size,
 499                          is_tlab,
 500                          run_verification && VerifyGCLevel <= 1,
 501                          do_clear_all_soft_refs,
 502                          true);
 503 
 504       must_restore_marks_for_biased_locking = true;
 505       max_level_collected = 1;
 506     }
 507 
 508     // Update "complete" boolean wrt what actually transpired --
 509     // for instance, a promotion failure could have led to
 510     // a whole heap collection.
 511     complete = complete || (max_level_collected == n_gens() - 1);
 512 
 513     if (complete) { // We did a "major" collection
 514       // FIXME: See comment at pre_full_gc_dump call
 515       post_full_gc_dump(NULL);   // do any post full gc dumps
 516     }
 517 
 518     if (PrintGCDetails) {
 519       print_heap_change(gch_prev_used);
 520 
 521       // Print metaspace info for full GC with PrintGCDetails flag.
 522       if (complete) {
 523         MetaspaceAux::print_metaspace_change(metadata_prev_used);
 524       }
 525     }
 526 
 527     // Adjust generation sizes.
 528     if (max_level_collected == 1) {
 529       _old_gen->compute_new_size();
 530     }
 531     _young_gen->compute_new_size();
 532 
 533     if (complete) {
 534       // Delete metaspaces for unloaded class loaders and clean up loader_data graph
 535       ClassLoaderDataGraph::purge();
 536       MetaspaceAux::verify_metrics();
 537       // Resize the metaspace capacity after full collections
 538       MetaspaceGC::compute_new_size();
 539       update_full_collections_completed();
 540     }
 541 
 542     // Track memory usage and detect low memory after GC finishes
 543     MemoryService::track_memory_usage();
 544 
 545     gc_epilogue(complete);
 546 
 547     if (must_restore_marks_for_biased_locking) {
 548       BiasedLocking::restore_marks();
 549     }
 550   }
 551 
 552   print_heap_after_gc();
 553 
 554 #ifdef TRACESPINNING
 555   ParallelTaskTerminator::print_termination_counts();
 556 #endif
 557 }
 558 
 559 HeapWord* GenCollectedHeap::satisfy_failed_allocation(size_t size, bool is_tlab) {
 560   return collector_policy()->satisfy_failed_allocation(size, is_tlab);
 561 }
 562 
 563 void GenCollectedHeap::set_par_threads(uint t) {
 564   SharedHeap::set_par_threads(t);
 565   set_n_termination(t);
 566 }
 567 
 568 void GenCollectedHeap::set_n_termination(uint t) {
 569   _process_strong_tasks->set_n_threads(t);
 570 }
 571 
 572 #ifdef ASSERT
 573 class AssertNonScavengableClosure: public OopClosure {
 574 public:
 575   virtual void do_oop(oop* p) {
 576     assert(!GenCollectedHeap::heap()->is_in_partial_collection(*p),
 577       "Referent should not be scavengable.");  }
 578   virtual void do_oop(narrowOop* p) { ShouldNotReachHere(); }
 579 };
 580 static AssertNonScavengableClosure assert_is_non_scavengable_closure;
 581 #endif
 582 
 583 void GenCollectedHeap::process_roots(bool activate_scope,
 584                                      ScanningOption so,
 585                                      OopClosure* strong_roots,
 586                                      OopClosure* weak_roots,
 587                                      CLDClosure* strong_cld_closure,
 588                                      CLDClosure* weak_cld_closure,
 589                                      CodeBlobClosure* code_roots) {
 590   StrongRootsScope srs(this, activate_scope);
 591 
 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 =n_par_threads() > 0;
 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 (CollectedHeap::use_parallel_gc_threads()) {
 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 
 670 void GenCollectedHeap::gen_process_roots(int level,
 671                                          bool younger_gens_as_roots,
 672                                          bool activate_scope,
 673                                          ScanningOption so,
 674                                          bool only_strong_roots,
 675                                          OopsInGenClosure* not_older_gens,
 676                                          OopsInGenClosure* older_gens,
 677                                          CLDClosure* cld_closure) {
 678   const bool is_adjust_phase = !only_strong_roots && !younger_gens_as_roots;
 679 
 680   bool is_moving_collection = false;
 681   if (level == 0 || is_adjust_phase) {
 682     // young collections are always moving
 683     is_moving_collection = true;
 684   }
 685 
 686   MarkingCodeBlobClosure mark_code_closure(not_older_gens, is_moving_collection);
 687   OopsInGenClosure* weak_roots = only_strong_roots ? NULL : not_older_gens;
 688   CLDClosure* weak_cld_closure = only_strong_roots ? NULL : cld_closure;
 689 
 690   process_roots(activate_scope, so,
 691                 not_older_gens, weak_roots,
 692                 cld_closure, weak_cld_closure,
 693                 &mark_code_closure);
 694 
 695   if (younger_gens_as_roots) {
 696     if (!_process_strong_tasks->is_task_claimed(GCH_PS_younger_gens)) {
 697       if (level == 1) {
 698         not_older_gens->set_generation(_young_gen);
 699         _young_gen->oop_iterate(not_older_gens);
 700       }
 701       not_older_gens->reset_generation();
 702     }
 703   }
 704   // When collection is parallel, all threads get to cooperate to do
 705   // older-gen scanning.
 706   if (level == 0) {
 707     older_gens->set_generation(_old_gen);
 708     rem_set()->younger_refs_iterate(_old_gen, older_gens);
 709     older_gens->reset_generation();
 710   }
 711 
 712   _process_strong_tasks->all_tasks_completed();
 713 }
 714 
 715 
 716 class AlwaysTrueClosure: public BoolObjectClosure {
 717 public:
 718   bool do_object_b(oop p) { return true; }
 719 };
 720 static AlwaysTrueClosure always_true;
 721 
 722 void GenCollectedHeap::gen_process_weak_roots(OopClosure* root_closure) {
 723   JNIHandles::weak_oops_do(&always_true, root_closure);
 724   _young_gen->ref_processor()->weak_oops_do(root_closure);
 725   _old_gen->ref_processor()->weak_oops_do(root_closure);
 726 }
 727 
 728 #define GCH_SINCE_SAVE_MARKS_ITERATE_DEFN(OopClosureType, nv_suffix)    \
 729 void GenCollectedHeap::                                                 \
 730 oop_since_save_marks_iterate(int level,                                 \
 731                              OopClosureType* cur,                       \
 732                              OopClosureType* older) {                   \
 733   if (level == 0) {                                                     \
 734     _young_gen->oop_since_save_marks_iterate##nv_suffix(cur);           \
 735     _old_gen->oop_since_save_marks_iterate##nv_suffix(older);           \
 736   } else {                                                              \
 737     _old_gen->oop_since_save_marks_iterate##nv_suffix(cur);             \
 738   }                                                                     \
 739 }
 740 
 741 ALL_SINCE_SAVE_MARKS_CLOSURES(GCH_SINCE_SAVE_MARKS_ITERATE_DEFN)
 742 
 743 #undef GCH_SINCE_SAVE_MARKS_ITERATE_DEFN
 744 
 745 bool GenCollectedHeap::no_allocs_since_save_marks(int level) {
 746   if (level == 0 && !_young_gen->no_allocs_since_save_marks()) {
 747     return false;
 748   }
 749   return _old_gen->no_allocs_since_save_marks();
 750 }
 751 
 752 bool GenCollectedHeap::supports_inline_contig_alloc() const {
 753   return _young_gen->supports_inline_contig_alloc();
 754 }
 755 
 756 HeapWord** GenCollectedHeap::top_addr() const {
 757   return _young_gen->top_addr();
 758 }
 759 
 760 HeapWord** GenCollectedHeap::end_addr() const {
 761   return _young_gen->end_addr();
 762 }
 763 
 764 // public collection interfaces
 765 
 766 void GenCollectedHeap::collect(GCCause::Cause cause) {
 767   if (should_do_concurrent_full_gc(cause)) {
 768 #if INCLUDE_ALL_GCS
 769     // mostly concurrent full collection
 770     collect_mostly_concurrent(cause);
 771 #else  // INCLUDE_ALL_GCS
 772     ShouldNotReachHere();
 773 #endif // INCLUDE_ALL_GCS
 774   } else if (cause == GCCause::_wb_young_gc) {
 775     // minor collection for WhiteBox API
 776     collect(cause, 0);
 777   } else {
 778 #ifdef ASSERT
 779   if (cause == GCCause::_scavenge_alot) {
 780     // minor collection only
 781     collect(cause, 0);
 782   } else {
 783     // Stop-the-world full collection
 784     collect(cause, n_gens() - 1);
 785   }
 786 #else
 787     // Stop-the-world full collection
 788     collect(cause, n_gens() - 1);
 789 #endif
 790   }
 791 }
 792 
 793 void GenCollectedHeap::collect(GCCause::Cause cause, int max_level) {
 794   // The caller doesn't have the Heap_lock
 795   assert(!Heap_lock->owned_by_self(), "this thread should not own the Heap_lock");
 796   MutexLocker ml(Heap_lock);
 797   collect_locked(cause, max_level);
 798 }
 799 
 800 void GenCollectedHeap::collect_locked(GCCause::Cause cause) {
 801   // The caller has the Heap_lock
 802   assert(Heap_lock->owned_by_self(), "this thread should own the Heap_lock");
 803   collect_locked(cause, n_gens() - 1);
 804 }
 805 
 806 // this is the private collection interface
 807 // The Heap_lock is expected to be held on entry.
 808 
 809 void GenCollectedHeap::collect_locked(GCCause::Cause cause, int max_level) {
 810   // Read the GC count while holding the Heap_lock
 811   unsigned int gc_count_before      = total_collections();
 812   unsigned int full_gc_count_before = total_full_collections();
 813   {
 814     MutexUnlocker mu(Heap_lock);  // give up heap lock, execute gets it back
 815     VM_GenCollectFull op(gc_count_before, full_gc_count_before,
 816                          cause, max_level);
 817     VMThread::execute(&op);
 818   }
 819 }
 820 
 821 #if INCLUDE_ALL_GCS
 822 bool GenCollectedHeap::create_cms_collector() {
 823 
 824   assert(_old_gen->kind() == Generation::ConcurrentMarkSweep,
 825          "Unexpected generation kinds");
 826   // Skip two header words in the block content verification
 827   NOT_PRODUCT(_skip_header_HeapWords = CMSCollector::skip_header_HeapWords();)
 828   CMSCollector* collector = new CMSCollector(
 829     (ConcurrentMarkSweepGeneration*)_old_gen,
 830     _rem_set->as_CardTableRS(),
 831     (ConcurrentMarkSweepPolicy*) collector_policy());
 832 
 833   if (collector == NULL || !collector->completed_initialization()) {
 834     if (collector) {
 835       delete collector;  // Be nice in embedded situation
 836     }
 837     vm_shutdown_during_initialization("Could not create CMS collector");
 838     return false;
 839   }
 840   return true;  // success
 841 }
 842 
 843 void GenCollectedHeap::collect_mostly_concurrent(GCCause::Cause cause) {
 844   assert(!Heap_lock->owned_by_self(), "Should not own Heap_lock");
 845 
 846   MutexLocker ml(Heap_lock);
 847   // Read the GC counts while holding the Heap_lock
 848   unsigned int full_gc_count_before = total_full_collections();
 849   unsigned int gc_count_before      = total_collections();
 850   {
 851     MutexUnlocker mu(Heap_lock);
 852     VM_GenCollectFullConcurrent op(gc_count_before, full_gc_count_before, cause);
 853     VMThread::execute(&op);
 854   }
 855 }
 856 #endif // INCLUDE_ALL_GCS
 857 
 858 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs) {
 859    do_full_collection(clear_all_soft_refs, _n_gens - 1);
 860 }
 861 
 862 void GenCollectedHeap::do_full_collection(bool clear_all_soft_refs,
 863                                           int max_level) {
 864   int local_max_level;
 865   if (!incremental_collection_will_fail(false /* don't consult_young */) &&
 866       gc_cause() == GCCause::_gc_locker) {
 867     local_max_level = 0;
 868   } else {
 869     local_max_level = max_level;
 870   }
 871 
 872   do_collection(true                 /* full */,
 873                 clear_all_soft_refs  /* clear_all_soft_refs */,
 874                 0                    /* size */,
 875                 false                /* is_tlab */,
 876                 local_max_level      /* max_level */);
 877   // Hack XXX FIX ME !!!
 878   // A scavenge may not have been attempted, or may have
 879   // been attempted and failed, because the old gen was too full
 880   if (local_max_level == 0 && gc_cause() == GCCause::_gc_locker &&
 881       incremental_collection_will_fail(false /* don't consult_young */)) {
 882     if (PrintGCDetails) {
 883       gclog_or_tty->print_cr("GC locker: Trying a full collection "
 884                              "because scavenge failed");
 885     }
 886     // This time allow the old gen to be collected as well
 887     do_collection(true                 /* full */,
 888                   clear_all_soft_refs  /* clear_all_soft_refs */,
 889                   0                    /* size */,
 890                   false                /* is_tlab */,
 891                   n_gens() - 1         /* max_level */);
 892   }
 893 }
 894 
 895 bool GenCollectedHeap::is_in_young(oop p) {
 896   bool result = ((HeapWord*)p) < _old_gen->reserved().start();
 897   assert(result == _young_gen->is_in_reserved(p),
 898          err_msg("incorrect test - result=%d, p=" INTPTR_FORMAT, result, p2i((void*)p)));
 899   return result;
 900 }
 901 
 902 // Returns "TRUE" iff "p" points into the committed areas of the heap.
 903 bool GenCollectedHeap::is_in(const void* p) const {
 904   #ifndef ASSERT
 905   guarantee(VerifyBeforeGC      ||
 906             VerifyDuringGC      ||
 907             VerifyBeforeExit    ||
 908             VerifyDuringStartup ||
 909             PrintAssembly       ||
 910             tty->count() != 0   ||   // already printing
 911             VerifyAfterGC       ||
 912     VMError::fatal_error_in_progress(), "too expensive");
 913 
 914   #endif
 915   return _young_gen->is_in(p) || _old_gen->is_in(p);
 916 }
 917 
 918 #ifdef ASSERT
 919 // Don't implement this by using is_in_young().  This method is used
 920 // in some cases to check that is_in_young() is correct.
 921 bool GenCollectedHeap::is_in_partial_collection(const void* p) {
 922   assert(is_in_reserved(p) || p == NULL,
 923     "Does not work if address is non-null and outside of the heap");
 924   return p < _young_gen->reserved().end() && p != NULL;
 925 }
 926 #endif
 927 
 928 void GenCollectedHeap::oop_iterate(ExtendedOopClosure* cl) {
 929   _young_gen->oop_iterate(cl);
 930   _old_gen->oop_iterate(cl);
 931 }
 932 
 933 void GenCollectedHeap::object_iterate(ObjectClosure* cl) {
 934   _young_gen->object_iterate(cl);
 935   _old_gen->object_iterate(cl);
 936 }
 937 
 938 void GenCollectedHeap::safe_object_iterate(ObjectClosure* cl) {
 939   _young_gen->safe_object_iterate(cl);
 940   _old_gen->safe_object_iterate(cl);
 941 }
 942 
 943 Space* GenCollectedHeap::space_containing(const void* addr) const {
 944   Space* res = _young_gen->space_containing(addr);
 945   if (res != NULL) {
 946     return res;
 947   }
 948   res = _old_gen->space_containing(addr);
 949   assert(res != NULL, "Could not find containing space");
 950   return res;
 951 }
 952 
 953 HeapWord* GenCollectedHeap::block_start(const void* addr) const {
 954   assert(is_in_reserved(addr), "block_start of address outside of heap");
 955   if (_young_gen->is_in_reserved(addr)) {
 956     assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
 957     return _young_gen->block_start(addr);
 958   }
 959 
 960   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
 961   assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
 962   return _old_gen->block_start(addr);
 963 }
 964 
 965 size_t GenCollectedHeap::block_size(const HeapWord* addr) const {
 966   assert(is_in_reserved(addr), "block_size of address outside of heap");
 967   if (_young_gen->is_in_reserved(addr)) {
 968     assert(_young_gen->is_in(addr), "addr should be in allocated part of generation");
 969     return _young_gen->block_size(addr);
 970   }
 971 
 972   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
 973   assert(_old_gen->is_in(addr), "addr should be in allocated part of generation");
 974   return _old_gen->block_size(addr);
 975 }
 976 
 977 bool GenCollectedHeap::block_is_obj(const HeapWord* addr) const {
 978   assert(is_in_reserved(addr), "block_is_obj of address outside of heap");
 979   assert(block_start(addr) == addr, "addr must be a block start");
 980   if (_young_gen->is_in_reserved(addr)) {
 981     return _young_gen->block_is_obj(addr);
 982   }
 983 
 984   assert(_old_gen->is_in_reserved(addr), "Some generation should contain the address");
 985   return _old_gen->block_is_obj(addr);
 986 }
 987 
 988 bool GenCollectedHeap::supports_tlab_allocation() const {
 989   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
 990   return _young_gen->supports_tlab_allocation();
 991 }
 992 
 993 size_t GenCollectedHeap::tlab_capacity(Thread* thr) const {
 994   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
 995   if (_young_gen->supports_tlab_allocation()) {
 996     return _young_gen->tlab_capacity();
 997   }
 998   return 0;
 999 }
1000 
1001 size_t GenCollectedHeap::tlab_used(Thread* thr) const {
1002   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1003   if (_young_gen->supports_tlab_allocation()) {
1004     return _young_gen->tlab_used();
1005   }
1006   return 0;
1007 }
1008 
1009 size_t GenCollectedHeap::unsafe_max_tlab_alloc(Thread* thr) const {
1010   assert(!_old_gen->supports_tlab_allocation(), "Old gen supports TLAB allocation?!");
1011   if (_young_gen->supports_tlab_allocation()) {
1012     return _young_gen->unsafe_max_tlab_alloc();
1013   }
1014   return 0;
1015 }
1016 
1017 HeapWord* GenCollectedHeap::allocate_new_tlab(size_t size) {
1018   bool gc_overhead_limit_was_exceeded;
1019   return collector_policy()->mem_allocate_work(size /* size */,
1020                                                true /* is_tlab */,
1021                                                &gc_overhead_limit_was_exceeded);
1022 }
1023 
1024 // Requires "*prev_ptr" to be non-NULL.  Deletes and a block of minimal size
1025 // from the list headed by "*prev_ptr".
1026 static ScratchBlock *removeSmallestScratch(ScratchBlock **prev_ptr) {
1027   bool first = true;
1028   size_t min_size = 0;   // "first" makes this conceptually infinite.
1029   ScratchBlock **smallest_ptr, *smallest;
1030   ScratchBlock  *cur = *prev_ptr;
1031   while (cur) {
1032     assert(*prev_ptr == cur, "just checking");
1033     if (first || cur->num_words < min_size) {
1034       smallest_ptr = prev_ptr;
1035       smallest     = cur;
1036       min_size     = smallest->num_words;
1037       first        = false;
1038     }
1039     prev_ptr = &cur->next;
1040     cur     =  cur->next;
1041   }
1042   smallest      = *smallest_ptr;
1043   *smallest_ptr = smallest->next;
1044   return smallest;
1045 }
1046 
1047 // Sort the scratch block list headed by res into decreasing size order,
1048 // and set "res" to the result.
1049 static void sort_scratch_list(ScratchBlock*& list) {
1050   ScratchBlock* sorted = NULL;
1051   ScratchBlock* unsorted = list;
1052   while (unsorted) {
1053     ScratchBlock *smallest = removeSmallestScratch(&unsorted);
1054     smallest->next  = sorted;
1055     sorted          = smallest;
1056   }
1057   list = sorted;
1058 }
1059 
1060 ScratchBlock* GenCollectedHeap::gather_scratch(Generation* requestor,
1061                                                size_t max_alloc_words) {
1062   ScratchBlock* res = NULL;
1063   _young_gen->contribute_scratch(res, requestor, max_alloc_words);
1064   _old_gen->contribute_scratch(res, requestor, max_alloc_words);
1065   sort_scratch_list(res);
1066   return res;
1067 }
1068 
1069 void GenCollectedHeap::release_scratch() {
1070   _young_gen->reset_scratch();
1071   _old_gen->reset_scratch();
1072 }
1073 
1074 class GenPrepareForVerifyClosure: public GenCollectedHeap::GenClosure {
1075   void do_generation(Generation* gen) {
1076     gen->prepare_for_verify();
1077   }
1078 };
1079 
1080 void GenCollectedHeap::prepare_for_verify() {
1081   ensure_parsability(false);        // no need to retire TLABs
1082   GenPrepareForVerifyClosure blk;
1083   generation_iterate(&blk, false);
1084 }
1085 
1086 void GenCollectedHeap::generation_iterate(GenClosure* cl,
1087                                           bool old_to_young) {
1088   if (old_to_young) {
1089     cl->do_generation(_old_gen);
1090     cl->do_generation(_young_gen);
1091   } else {
1092     cl->do_generation(_young_gen);
1093     cl->do_generation(_old_gen);
1094   }
1095 }
1096 
1097 void GenCollectedHeap::space_iterate(SpaceClosure* cl) {
1098   _young_gen->space_iterate(cl, true);
1099   _old_gen->space_iterate(cl, true);
1100 }
1101 
1102 bool GenCollectedHeap::is_maximal_no_gc() const {
1103   return _young_gen->is_maximal_no_gc() && _old_gen->is_maximal_no_gc();
1104 }
1105 
1106 void GenCollectedHeap::save_marks() {
1107   _young_gen->save_marks();
1108   _old_gen->save_marks();
1109 }
1110 
1111 GenCollectedHeap* GenCollectedHeap::heap() {
1112   assert(_gch != NULL, "Uninitialized access to GenCollectedHeap::heap()");
1113   assert(_gch->kind() == CollectedHeap::GenCollectedHeap, "not a generational heap");
1114   return _gch;
1115 }
1116 
1117 
1118 void GenCollectedHeap::prepare_for_compaction() {
1119   guarantee(_n_gens = 2, "Wrong number of generations");
1120   // Start by compacting into same gen.
1121   CompactPoint cp(_old_gen);
1122   _old_gen->prepare_for_compaction(&cp);
1123   _young_gen->prepare_for_compaction(&cp);
1124 }
1125 
1126 GCStats* GenCollectedHeap::gc_stats(int level) const {
1127   if (level == 0) {
1128     return _young_gen->gc_stats();
1129   } else {
1130     return _old_gen->gc_stats();
1131   }
1132 }
1133 
1134 void GenCollectedHeap::verify(bool silent, VerifyOption option /* ignored */) {
1135   if (!silent) {
1136     gclog_or_tty->print("%s", _old_gen->name());
1137     gclog_or_tty->print(" ");
1138   }
1139   _old_gen->verify();
1140 
1141   if (!silent) {
1142     gclog_or_tty->print("%s", _young_gen->name());
1143     gclog_or_tty->print(" ");
1144   }
1145   _young_gen->verify();
1146 
1147   if (!silent) {
1148     gclog_or_tty->print("remset ");
1149   }
1150   rem_set()->verify();
1151 }
1152 
1153 void GenCollectedHeap::print_on(outputStream* st) const {
1154   _young_gen->print_on(st);
1155   _old_gen->print_on(st);
1156   MetaspaceAux::print_on(st);
1157 }
1158 
1159 void GenCollectedHeap::gc_threads_do(ThreadClosure* tc) const {
1160   if (workers() != NULL) {
1161     workers()->threads_do(tc);
1162   }
1163 #if INCLUDE_ALL_GCS
1164   if (UseConcMarkSweepGC) {
1165     ConcurrentMarkSweepThread::threads_do(tc);
1166   }
1167 #endif // INCLUDE_ALL_GCS
1168 }
1169 
1170 void GenCollectedHeap::print_gc_threads_on(outputStream* st) const {
1171 #if INCLUDE_ALL_GCS
1172   if (UseConcMarkSweepGC) {
1173     workers()->print_worker_threads_on(st);
1174     ConcurrentMarkSweepThread::print_all_on(st);
1175   }
1176 #endif // INCLUDE_ALL_GCS
1177 }
1178 
1179 void GenCollectedHeap::print_on_error(outputStream* st) const {
1180   this->CollectedHeap::print_on_error(st);
1181 
1182 #if INCLUDE_ALL_GCS
1183   if (UseConcMarkSweepGC) {
1184     st->cr();
1185     CMSCollector::print_on_error(st);
1186   }
1187 #endif // INCLUDE_ALL_GCS
1188 }
1189 
1190 void GenCollectedHeap::print_tracing_info() const {
1191   if (TraceYoungGenTime) {
1192     _young_gen->print_summary_info();
1193   }
1194   if (TraceOldGenTime) {
1195     _old_gen->print_summary_info();
1196   }
1197 }
1198 
1199 void GenCollectedHeap::print_heap_change(size_t prev_used) const {
1200   if (PrintGCDetails && Verbose) {
1201     gclog_or_tty->print(" "  SIZE_FORMAT
1202                         "->" SIZE_FORMAT
1203                         "("  SIZE_FORMAT ")",
1204                         prev_used, used(), capacity());
1205   } else {
1206     gclog_or_tty->print(" "  SIZE_FORMAT "K"
1207                         "->" SIZE_FORMAT "K"
1208                         "("  SIZE_FORMAT "K)",
1209                         prev_used / K, used() / K, capacity() / K);
1210   }
1211 }
1212 
1213 class GenGCPrologueClosure: public GenCollectedHeap::GenClosure {
1214  private:
1215   bool _full;
1216  public:
1217   void do_generation(Generation* gen) {
1218     gen->gc_prologue(_full);
1219   }
1220   GenGCPrologueClosure(bool full) : _full(full) {};
1221 };
1222 
1223 void GenCollectedHeap::gc_prologue(bool full) {
1224   assert(InlineCacheBuffer::is_empty(), "should have cleaned up ICBuffer");
1225 
1226   always_do_update_barrier = false;
1227   // Fill TLAB's and such
1228   CollectedHeap::accumulate_statistics_all_tlabs();
1229   ensure_parsability(true);   // retire TLABs
1230 
1231   // Walk generations
1232   GenGCPrologueClosure blk(full);
1233   generation_iterate(&blk, false);  // not old-to-young.
1234 };
1235 
1236 class GenGCEpilogueClosure: public GenCollectedHeap::GenClosure {
1237  private:
1238   bool _full;
1239  public:
1240   void do_generation(Generation* gen) {
1241     gen->gc_epilogue(_full);
1242   }
1243   GenGCEpilogueClosure(bool full) : _full(full) {};
1244 };
1245 
1246 void GenCollectedHeap::gc_epilogue(bool full) {
1247 #ifdef COMPILER2
1248   assert(DerivedPointerTable::is_empty(), "derived pointer present");
1249   size_t actual_gap = pointer_delta((HeapWord*) (max_uintx-3), *(end_addr()));
1250   guarantee(actual_gap > (size_t)FastAllocateSizeLimit, "inline allocation wraps");
1251 #endif /* COMPILER2 */
1252 
1253   resize_all_tlabs();
1254 
1255   GenGCEpilogueClosure blk(full);
1256   generation_iterate(&blk, false);  // not old-to-young.
1257 
1258   if (!CleanChunkPoolAsync) {
1259     Chunk::clean_chunk_pool();
1260   }
1261 
1262   MetaspaceCounters::update_performance_counters();
1263   CompressedClassSpaceCounters::update_performance_counters();
1264 
1265   always_do_update_barrier = UseConcMarkSweepGC;
1266 };
1267 
1268 #ifndef PRODUCT
1269 class GenGCSaveTopsBeforeGCClosure: public GenCollectedHeap::GenClosure {
1270  private:
1271  public:
1272   void do_generation(Generation* gen) {
1273     gen->record_spaces_top();
1274   }
1275 };
1276 
1277 void GenCollectedHeap::record_gen_tops_before_GC() {
1278   if (ZapUnusedHeapArea) {
1279     GenGCSaveTopsBeforeGCClosure blk;
1280     generation_iterate(&blk, false);  // not old-to-young.
1281   }
1282 }
1283 #endif  // not PRODUCT
1284 
1285 class GenEnsureParsabilityClosure: public GenCollectedHeap::GenClosure {
1286  public:
1287   void do_generation(Generation* gen) {
1288     gen->ensure_parsability();
1289   }
1290 };
1291 
1292 void GenCollectedHeap::ensure_parsability(bool retire_tlabs) {
1293   CollectedHeap::ensure_parsability(retire_tlabs);
1294   GenEnsureParsabilityClosure ep_cl;
1295   generation_iterate(&ep_cl, false);
1296 }
1297 
1298 oop GenCollectedHeap::handle_failed_promotion(Generation* old_gen,
1299                                               oop obj,
1300                                               size_t obj_size) {
1301   guarantee(old_gen->level() == 1, "We only get here with an old generation");
1302   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
1303   HeapWord* result = NULL;
1304 
1305   result = old_gen->expand_and_allocate(obj_size, false);
1306 
1307   if (result != NULL) {
1308     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
1309   }
1310   return oop(result);
1311 }
1312 
1313 class GenTimeOfLastGCClosure: public GenCollectedHeap::GenClosure {
1314   jlong _time;   // in ms
1315   jlong _now;    // in ms
1316 
1317  public:
1318   GenTimeOfLastGCClosure(jlong now) : _time(now), _now(now) { }
1319 
1320   jlong time() { return _time; }
1321 
1322   void do_generation(Generation* gen) {
1323     _time = MIN2(_time, gen->time_of_last_gc(_now));
1324   }
1325 };
1326 
1327 jlong GenCollectedHeap::millis_since_last_gc() {
1328   // We need a monotonically non-decreasing time in ms but
1329   // os::javaTimeMillis() does not guarantee monotonicity.
1330   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
1331   GenTimeOfLastGCClosure tolgc_cl(now);
1332   // iterate over generations getting the oldest
1333   // time that a generation was collected
1334   generation_iterate(&tolgc_cl, false);
1335 
1336   // javaTimeNanos() is guaranteed to be monotonically non-decreasing
1337   // provided the underlying platform provides such a time source
1338   // (and it is bug free). So we still have to guard against getting
1339   // back a time later than 'now'.
1340   jlong retVal = now - tolgc_cl.time();
1341   if (retVal < 0) {
1342     NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, retVal);)
1343     return 0;
1344   }
1345   return retVal;
1346 }