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