rr is a lightweight tool for recording, replaying and debugging execution of applications (trees of processes and threads). Debugging extends gdb with very efficient reverse-execution, which in combination with standard gdb/x86 features like hardware data watchpoints, makes debugging much more fun. More information about the project, including instructions on how to install, run, and build rr, is at https://rr-project.org. The best technical overview is currently the paper Engineering Record And Replay For Deployability: Extended Technical Report.

Or go directly to the installation and building instructions.

Please contribute! Make sure to review the pull request checklist before submitting a pull request.

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rr development is sponsored by Pernosco and was originated by Mozilla.

• Linux kernel >= 4.7 (for support of __WALL in waitid())
  • rr 5.6.0 worked with kernel 3.11 (requiring PTRACE_SETSIGMASK)
• rr currently requires either:
  • An Intel CPU with Nehalem (2010) or later microarchitecture.
  • Certain AMD Zen or later processors (see https://github.com/rr-debugger/rr/wiki/Zen)
  • Certain AArch64 microarchitectures (e.g. ARM Neoverse N1 or the Apple Silicon M-series)
• Running in a VM guest is supported, as long as the VM supports virtualization of hardware performance counters.
  • Some configurations of VMware and KVM are known to work.
  • Some configurations of AWS and GCP VMs are known to work.
  • No configurations of Xen are known to work.