'Called when a new worker is started.
:param socket sock: The listen socket for the worker just started.
:param server_idx: The socket\'s server_idx as yielded by
:py:meth:`new_worker_socks`.
:param int pid: The new worker process\' PID'

def register_worker_start(self, sock, server_idx, pid):

    port = self.port_pid_state.port_for_sock(sock)
    self.logger.notice('Started    child    %d    (PID    %d)    for    port    %d', server_idx, pid, port)
    self.port_pid_state.add_pid(port, server_idx, pid)
