libevent и все все все

http://www.kegel.com/c10k.html

http://www.wangafu.net/~nickm/libevent-book/

https://habr.com/ru/post/217437/

https://habr.com/ru/post/152345/

https://unix4lyfe.org/darkhttpd/
https://askubuntu.com/questions/1102594/how-do-i-set-up-the-simplest-http-local-server

Super!!!

https://github.com/raybellis/evldns

libevent study

https://github.com/gszhuang/libevent_study/releases

http://www.transmissionbt.com

http://www.haproxy.org