void ConcurrentMark::checkpointRootsFinalWork() {

  {- -------------------------------------------
  (1) (変数宣言など)
      ---------------------------------------- -}

      ResourceMark rm;
      HandleMark   hm;
      G1CollectedHeap* g1h = G1CollectedHeap::heap();

  {- -------------------------------------------
  (1) GC 処理の前に, CollectedHeap::ensure_parsability() を呼んで
      各 TLAB に残っている未使用領域を埋め, 
      オブジェクトでひとつながりの状態(= GC で辿れる状態)にしておく.
      ---------------------------------------- -}

      g1h->ensure_parsability(false);

  {- -------------------------------------------
  (1) CMRemarkTask::work() で Final marking pause 処理を行う.
      (なお, G1CollectedHeap::use_parallel_gc_threads() が true の場合は, 
       WorkGang::run_task() 経由で呼び出す.
       これにより, 処理がマルチスレッドで実行される)

      (ついでに, 処理の実行前には ConcurrentMark::set_phase() も呼んで... #TODO)
      ---------------------------------------- -}

      if (G1CollectedHeap::use_parallel_gc_threads()) {
        G1CollectedHeap::StrongRootsScope srs(g1h);
        // this is remark, so we'll use up all available threads
        int active_workers = ParallelGCThreads;
        set_phase(active_workers, false /* concurrent */);

        CMRemarkTask remarkTask(this);
        // We will start all available threads, even if we decide that the
        // active_workers will be fewer. The extra ones will just bail out
        // immediately.
        int n_workers = g1h->workers()->total_workers();
        g1h->set_par_threads(n_workers);
        g1h->workers()->run_task(&remarkTask);
        g1h->set_par_threads(0);
      } else {
        G1CollectedHeap::StrongRootsScope srs(g1h);
        // this is remark, so we'll use up all available threads
        int active_workers = 1;
        set_phase(active_workers, false /* concurrent */);

        CMRemarkTask remarkTask(this);
        // We will start all available threads, even if we decide that the
        // active_workers will be fewer. The extra ones will just bail out
        // immediately.
        remarkTask.work(0);
      }

  {- -------------------------------------------
  (1) (assert)
      ---------------------------------------- -}

      SATBMarkQueueSet& satb_mq_set = JavaThread::satb_mark_queue_set();
      guarantee(satb_mq_set.completed_buffers_num() == 0, "invariant");

  {- -------------------------------------------
  (1) (トレース出力)
      ---------------------------------------- -}

      print_stats();

  {- -------------------------------------------
  (1) (assert)
      ---------------------------------------- -}

    #if VERIFY_OBJS_PROCESSED
      if (_scan_obj_cl.objs_processed != ThreadLocalObjQueue::objs_enqueued) {
        gclog_or_tty->print_cr("Processed = %d, enqueued = %d.",
                               _scan_obj_cl.objs_processed,
                               ThreadLocalObjQueue::objs_enqueued);
        guarantee(_scan_obj_cl.objs_processed ==
                  ThreadLocalObjQueue::objs_enqueued,
                  "Different number of objs processed and enqueued.");
      }
    #endif
    }