Race conditions are a natural hazard whenever working with shared resources. If you have multiple processes such as using a database, or a microservice architecture, there are likely some race conditions that are hiding in your code. As usage scales up, they will become more and more common. They are difficult to detect, challenging to reproduce and test, and sometimes downright hard to prove that it is fixed. In this talk, we will dive into what a race condition is, how it can show up in Rails applications, and some strategies on how to test them to give confidence that they are fixed.