리눅스 IO

https://djkeh.github.io//djkeh.github.io/articles/Boost-application-performance-using-asynchronous-IO-kor/

https://homoefficio.github.io/2017/02/19/Blocking-NonBlocking-Synchronous-Asynchronous/index.html

Epoll

https://medium.com/@copyconstruct/the-method-to-epolls-madness-d9d2d6378642