The first lines of Parse code were written nearly four years ago. In 2011 Parse was a crazy little idea to solve the problem of building mobile apps. Those first few lines were written in Ruby on Rails. Ruby on Rails Ruby let us get the first versions of Parse out the door quickly. It let a small team of engineers iterate on it and add functionality very fast. There was a deep bench of library support, gems, deploy tooling, and best practices available, so we didn't have to reinvent very many wheels. We used Unicorn as our HTTP server, Capistrano to deploy code, RVM to manage the environment, and a zillion open source gems to handle things like YAML parsing, oauth, JSON parsing, MongoDB, and MySQL. We also used Chef which is Ruby-based to manage our infrastructure so everything played together nicely. For a while. The first signs of trouble bubbled up in the deploy process. As our code base grew, it took longer and longer to deploy, and the “graceful” unicorn restarts really weren't