My last post about Twitter unsurprisingly drew the responses of the super duper microblogging interconnected developers at Twitter.
I'm still confused as to why Starling ever came about in the first place, but their reasoning for the move to Scala is a lot clearer now. They want a statically typed language to manage a larger codebase, and a faster language so they can grow to handle more load. It would seem their entire system is both stateful and high throughput, for which they need a high performance disk logged message queue.
However, for the one stateless part of their system, the webapp, I guess they're going to stick with Ruby, and the good old Matz Ruby Interpreter. JRuby won't run their app for some reason.
That's at least what I digested from the Twitter employees. Thanks for your replies.