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