rr

rr is a lightweight recording and deterministic debugging tool for C and C++ programs on Linux, which enhances gdb. A failure is recorded once, then the recording can be debugged deterministically as many times as needed: the same execution is replayed every time.

rr also provides efficient reverse execution under gdb: breakpoints and data watchpoints can be set, then execution runs backwards to where they were hit. It has a low overhead compared with similar tools and works on real applications, which makes it useful to capture intermittent failures, for example in test suites, and analyse them afterwards.

rr was started at Mozilla and is free and open source under an MIT-style licence. Its development is sponsored by Pernosco.