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