def METHOD_NAME(self):
    # sampling clients
    client_indexes = self.aggregator.client_sampling(
        self.args.round_idx,
        self.args.client_num_in_total,
        self.args.client_num_per_round,
    )
    global_model_params = self.aggregator.get_global_model_params()
    for process_id in range(1, self.size):
        self.send_message_init_config(
            process_id, global_model_params, client_indexes[process_id - 1]
        )