While it is possible that Starling had been running internally before its release, this does not excuse overlooking rabbitmq. A software package that had proven itself in real-world scaling and been designed by people with real experience in the problem domain (c.f. the financial services world) is going to be much better at "alpha" or "beta" quality than Starling is going to be even after the twitter devs hammer at it for a couple of years. The twitter devs were starting from scratch, writing something that other people out there actually had some experience with, and decided to not take an existing solution and fix/adapt it to their needs.
I take issue with the idea that the financial services world has real experience in Twitter's problem domain. My experience with the financial services world is significant technically, but casual in a career sense. That said:
I think hi-fi devs make lots of stupid decisions in the name of performance. In the few cases where their actual outcomes match up to their posturing, it's because their code is obsessively cobbled around one specific use case they've been working on since 1989.
Have you ever read an order management system, or looked at Tibco Rendezvous on the wire?
Most of the hi-fi companies adopting MQ are built around straight AMQ, and bare-metal performance was out the window long before they bolted their crappy WebSphere app onto it. What these companies are looking for is predictability, not performance, and their problem sets are much simpler and most stable than Twitter's.
RabbitMQ was less than a year old, and significantly more fully featured than what Twitter needed. Fixing bugs in that would be a whole lot harder than fixing bugs in 1500 lines of code they wrote in a language they knew.
