code: def _start_lock_renewer(self):
          
          if self._lock_renewal_thread is not None:
              raise AlreadyStarted("Lock refresh thread already started")
  
          logger.debug(
              "Starting thread to refresh lock every %s seconds",
              self._lock_renewal_interval
          )
          self._lock_renewal_stop = threading.Event()
          self._lock_renewal_thread = threading.Thread(
              group=None,
              target=self._lock_renewer,
              kwargs={'lockref': weakref.ref(self),
                      'interval': self._lock_renewal_interval,
                      'stop': self._lock_renewal_stop}
          )
          self._lock_renewal_thread.setDaemon(True)
          self._lock_renewal_thread.start()
docs: Starts the lock refresher thread.