In this talk I'll discuss the architectural underpinnings of Tumblr's distributed systems infrastructure. I'll focus primarily on Motherboy, an eventually consistent inbox style storage system, to highlight some of the most useful lessons learned. Additionally, I'll discuss some of our findings in evaluating various concurrency models as well as how our choice of Scala as our back-end language of choice, played into those decisions. This talk will be targeted towards distributed systems developers but will also have some appeal to operations engineers who are responsible for managing these JVM based systems. Some key concepts covered will include concurrency constructs available on the JVM, testing and tuning the stack, Scala in a distributed systems context, real world benchmarking and distributed tracing.