Luasocket does async IO. It uses poll or select on Unix (calling it 'select'); I'm not familiar with what it uses on Windows. It's not "web scale", but is very

Luasocket does async IO. It uses poll or select on Unix (calling it 'select'); I'm not familiar with what it uses on Windows. It's not "web scale", but is very easy to use, and works well enough for a couple hundred simultaneous connections. Lua's convenient C API means that wrapping libev, libuv, or libevent is really not hard, if you want to go that route. (I have a libev wrapper on github, FWIW.) The thing to keep in mind is that if you're writing high-throughput servers, you probably want to avoid parsing the network IO via Lua. While Lua strings are fine with arbitrary binary data (i.e., \0s are fine), it interns all strings; you'll have the overhead of converting every read into an atom/symbol, and it will spend a lot of time garbage collecting. (Lua makes this daring trade-off because it's usually a net win, and when it isn't, you still have the option of doing things in C instead.) Lua's great for handling all the control logic, though. Coroutines are particularly applicable there. In a nutshell: If you're good with C, and understand the issues involved with performant async IO, Lua can work very well.