I'd just like to mention popol here [1]:

    Popol is designed as a minimal ergonomic wrapper
    around poll, built for use cases such as peer-to-peer
    networking, where you typically have no more than a
    few hundred concurrent connections. It’s meant to be
    familiar enough for those with experience using mio,
    but a little easier to use, and a lot smaller.

[1]: https://cloudhead.io/popol/