Yeah but the parser has got nothing to do with I/O concurrency. Rack is not thread-safe, it's merely reentrant by design. If you're happy with Thin right now,

Yeah but the parser has got nothing to do with I/O concurrency. Rack is not thread-safe, it's merely reentrant by design. If you're happy with Thin right now, by all means, stick with Thin. No offense taken.