code: void startTaskTrackers(ClusterStory clusterStory, long now) {
      /** port assigned to TTs, incremented by 1 for each TT */
      int port = 10000;
      long ms = now + 100;
  
      for (MachineNode node : clusterStory.getMachines()) {
        String hostname = node.getName();
        RackNode rackNode = node.getRackNode();
        StaticMapping.addNodeToRack(hostname, rackNode.getName());
        String taskTrackerName = "tracker_" + hostname + ":localhost/127.0.0.1:"
            + port;
        port++;
        SimulatorTaskTracker tt = new SimulatorTaskTracker(jt, taskTrackerName,
            hostname, node.getMapSlots(), node.getReduceSlots());
        queue.addAll(tt.init(ms++));
      }
    }
docs: Start simulated task trackers based on topology.
  @param clusterStory The cluster topology.
  @param now
  time stamp when the simulator is started, {@link SimulatorTaskTracker}s
  are started shortly after this time stamp