Debugging with RR ¶

​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.

Using RR with the SDK ¶

The Flatpak SDK already provides RR. You don't need to install it on your host machine. To record a trace, use this command:

$ WEBKIT_MINI_BROWSER_PREFIX=rr Tools/Scripts/run-minibrowser --gtk ...

You don't necessarily need a debug build, but it's better to have one.

To replay a trace or simply run rr:

$ Tools/Scripts/webkit-flatpak -c rr <rr arguments here>
...
$ Tools/Scripts/webkit-flatpak -c rr ps                                                                                                                                                            14:32:37
PID     PPID    EXIT    CMD
35      --      0       /app/webkit/WebKitBuild/Debug/bin/MiniBrowser http://192.168.1.44/test.html
43      35      -5      /app/webkit/WebKitBuild/Debug/bin/WebKitWebProcess 7 24
44      35      0       /app/webkit/WebKitBuild/Debug/bin/WebKitNetworkProcess 8 24