In computing, rr is a debugging tool for Linux designed to record and replay program execution.

During the replay phase, rr provides an enhanced gdb debugging experience that supports reverse execution.

[2] rr is now widely used outside Mozilla and capable of debugging software such as Google Chrome, QEMU, and LibreOffice.

During replay rr will act as a gdbserver providing a gdb experience capable of reverse-execution.

Because a bug can be replayed over and over again, rr enables new methods of debugging issues that are very difficult to solve with traditional debuggers.