Run a process to monitor the other processes.

    Args:
        redis_address (str): The address that the Redis server is listening on.
        stdout_file: A file handle opened for writing to redirect stdout to. If
            no redirection should happen, then this should be None.
        stderr_file: A file handle opened for writing to redirect stderr to. If
            no redirection should happen, then this should be None.
        autoscaling_config: path to autoscaling config file.
        redis_password (str): The password of the redis server.

    Returns:
        ProcessInfo for the process that was started.

def start_monitor(redis_address,
                  stdout_file=None,
                  stderr_file=None,
                  autoscaling_config=None,
                  redis_password=None):
    """Run a process to monitor the other processes.

    Args:
        redis_address (str): The address that the Redis server is listening on.
        stdout_file: A file handle opened for writing to redirect stdout to. If
            no redirection should happen, then this should be None.
        stderr_file: A file handle opened for writing to redirect stderr to. If
            no redirection should happen, then this should be None.
        autoscaling_config: path to autoscaling config file.
        redis_password (str): The password of the redis server.

    Returns:
        ProcessInfo for the process that was started.
    """
    monitor_path = os.path.join(
        os.path.dirname(os.path.abspath(__file__)), "monitor.py")
    command = [
        sys.executable, "-u", monitor_path,
        "--redis-address=" + str(redis_address)
    ]
    if autoscaling_config:
        command.append("--autoscaling-config=" + str(autoscaling_config))
    if redis_password:
        command.append("--redis-password=" + redis_password)
    process_info = start_ray_process(
        command,
        ray_constants.PROCESS_TYPE_MONITOR,
        stdout_file=stdout_file,
        stderr_file=stderr_file)
    return process_info