Ever tried reproducing intermittent failures by rerunning a test 100 times, or stared at core dumps where a variable was obviously wrong but you couldn’t figure out why? Mozilla’s rr records test execution with minimal overhead, and provides you with compact and deterministic execution traces that you can replay forwards and backwards in time.

In this talk, we’ll focus on how to use rr to simplify your debugging life in practice, briefly describe how it works under the hood and compare it to other reversible debuggers, and watch a few snippets of good rr talks.