def METHOD_NAME(self, allow_missing=True) -> int:
    """Count the number of servers available in the tracker
    Parameters
    ----------
    allow_missing : bool
        Whether to allow no server to be found.
    Returns
    -------
    num_servers : int
        The number of servers
    """
    tracker = self.connect_tracker()
    tracker_summary = tracker.summary()
    result: int = 0
    for item in tracker_summary["server_info"]:
        _, item_key = item["key"].split(":")
        if item_key == self.tracker_key:
            result += 1
    if result == 0 and not allow_missing:
        raise ValueError(
            "Unable to find servers with the specific key using the following configuration:\n"
            f"    tracker host: {self.tracker_host}\n"
            f"    tracker port: {self.tracker_port}\n"
            f"    tracker key: {self.tracker_key}\n"
            f"    timeout (sec): {self.session_timeout_sec}\n"
            "Please check the tracker status via the following command:\n"
            "     python3 -m tvm.exec.query_rpc_tracker "
            f"--host {self.tracker_host} --port {self.tracker_port}\n"
            f'and look for key: "{self.tracker_key}"'
        )
    return result