生成CSRF时报504 [ 新手入门 ]

我在表单中加入

// mcrypt_create_iv() does not use libmcrypt. Since PHP 5.3.7 it directly reads

    // CryptGenRandom on Windows. Elsewhere it directly reads /dev/urandom.
    if (function_exists('mcrypt_create_iv')) {
        $key = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
        if (StringHelper::byteLength($key) === $length) {
            return $key;
        }
    }

MCRYPT_DEV_URANDOM 这个参数也不会造成阻塞呀，为什么还报504呢