Puma uses a thread pool to handle requests. The only other Ruby web servers I know of that do this are Rainbows!, and Zbatery, and they're a bit obscure, unfort

Puma uses a thread pool to handle requests. The only other Ruby web servers I know of that do this are Rainbows!, and Zbatery, and they're a bit obscure, unfortunately. Unlike Thin, EventMachine is not used. I have it running on my Heroku instance for a day or so with no issues, though I don't get any traffic yet. :)