I've gotten our stack converted to Rails 4 (yea!)
and I'm looking to take advantage of the thread-safe code.
Puma works in getting up, stopping it appears to be a different problem :(
Is Puma the only multi-threaded rails?
Thin -> EventMachine
Unicorn -> Forking
Puma -> multi-threaded
Mongrel -> don't care
Webbrick -> don't care