docs: def start(self):
          """
          Start the configfile change monitoring thread.
  
          """
          fname = self.conf['file']
          logging.info("Configfile watcher plugin: Starting to watch route spec "
                       "file '%s' for changes..." % fname)
  
          # Initial content of file needs to be processed at least once, before
          # we start watching for any changes to it. Therefore, we will write it
          # out on the queue right away.
          route_spec = {}
          try:
              route_spec = read_route_spec_config(fname)
              if route_spec:
                  self.last_route_spec_update = datetime.datetime.now()
                  self.q_route_spec.put(route_spec)
          except ValueError as e:
              logging.warning("Cannot parse route spec: %s" % str(e))
  
          # Now prepare to watch for any changes in that file.  Find the parent
          # directory of the config file, since this is where we will attach a
          # watcher to.
          abspath    = os.path.abspath(fname)
          parent_dir = os.path.dirname(abspath)
  
          # Create the file watcher and run in endless loop
          handler = RouteSpecChangeEventHandler(
                                      route_spec_fname   = fname,
                                      route_spec_abspath = abspath,
                                      q_route_spec       = self.q_route_spec,
                                      plugin             = self)
          self.observer_thread = watchdog.observers.Observer()
          self.observer_thread.name = "ConfMon"
          self.observer_thread.schedule(handler, parent_dir)
          self.observer_thread.start()