Gatewayworker 代码获取网关服务地址，为何没主动关闭tcp连接。

protected static function getAllGatewayAddressesFromRegister()
    {
        static $addresses_cache, $last_update;
        $time_now = time();
        $expiration_time = 1;
        $register_addresses = (array)static::$registerAddress;
        if(empty($addresses_cache) || $time_now - $last_update > $expiration_time) {
            foreach ($register_addresses as $register_address) {
                $client = stream_socket_client('tcp://' . $register_address, $errno, $errmsg, static::$connectTimeout);
                if ($client) {
                    break;
                }
            }
            if (!$client) {
                throw new Exception('Can not connect to tcp://' . $register_address . ' ' . $errmsg);
            }

            fwrite($client, '{"event":"worker_connect","secret_key":"' . static::$secretKey . '"}' . "\n");
            stream_set_timeout($client, 5);
            $ret = fgets($client, 655350);
            if (!$ret || !$data = json_decode(trim($ret), true)) {
                throw new Exception('getAllGatewayAddressesFromRegister fail. tcp://' .
                    $register_address . ' return ' . var_export($ret, true));
            }
            $last_update = $time_now;
            $addresses_cache = $data['addresses'];

这段代码用 businessworker 身份去连接到register 服务器获取网关地址。
这段代码在获取到网关连接数，为啥没看见主动关闭tcp连接？