def METHOD_NAME(self):
    """
    Start database worker threads
    """
    # give a nice name to the process
    w.setproctitle('oq-dbserver')
    dworkers = []
    for _ in range(self.num_workers):
        sock = z.Socket(self.backend, z.zmq.REP, 'connect')
        threading.Thread(target=self.dworker, args=(sock,)).METHOD_NAME()
        dworkers.append(sock)
    logging.warning('DB server started with %s on %s, pid %d',
                    sys.executable, self.frontend, self.pid)
    # start frontend->backend proxy for the database workers
    try:
        z.zmq.proxy(z.bind(self.frontend, z.zmq.ROUTER),
                    z.bind(self.backend, z.zmq.DEALER))
    except (KeyboardInterrupt, z.zmq.ContextTerminated):
        for sock in dworkers:
            sock.running = False
            if hasattr(sock, 'zsocket'):  # actually used
                sock.zsocket.close()
        logging.warning('DB server stopped')
    finally:
        self.stop()