private function _getRequestPool(): Pool
    {
        return new Pool($this->_getClient(), $this->_getRequestPromise(), [
            'concurrency' => max(1, $this->configOfConcurrency),
            'fulfilled' => function () {
                call_user_func_array([$this, '_responseSuccessHandle'], func_get_args());
            },
            'rejected' => function () {
                call_user_func_array([$this, '_responseFailHandle'], func_get_args());
            }
        ]);
    }