Record and replay debugging is the process of recording the execution of a software program so that it may be played back within a debugger to help diagnose and resolve defects.^[1] The concept is analogous to the use of a flight data recorder to diagnose the cause of an airplane flight malfunction.^[2]

Recording and replaying

Record and replay debuggers record application state at every step of the program's process and thread execution, including memory interactions, deterministic and non-deterministic inputs, system resource status, and store it to disk in a log.^[3] The recording allows the program to be replayed again and again, and debugged exactly as it happened.

Usage

Recordings can be made in one location and replayed in another,^[4] which makes it useful for remote debugging.

Record and replay debugging is particularly useful for debugging intermittent and non-deterministic defects, which can be difficult to reproduce.

Record and replay debugging technology is often fundamental to reverse debugging and time travel debugging.

Record and replay debuggers

• GDB (GNU)^[5]
• LiveRecorder (Undo)^[6]
• rr (Mozilla)
• TotalView's ReplayEngine (RogueWave)^[7]
• PyTrace for Python^[8]