[lambda]

I haven't used rr, but I have used GDB's built in record and replay ability.

GDB's was quite useful, but painfully slow; I had to do a good amount of bisecting down to a small enough input to reproduce the issue without having to wait ages to execute before it was usable. Once I did that, though, it let me find the issue a lot sooner than I would have been able to otherwise.

rr promises to be substantially faster the GDB's record and replay; if so, I imagine it will be quite useful, though it is only once or twice a year that I actually have to debug a problem that these kinds of tools are relevant for.

[fijal]

undodb gdb (a commercial product) works a lot faster than gdb (which is so slow it's unusable). We used it with success to debug programs as big as pypy

[emmelaich]

rr uses/enhances gdb, so I guess you mean faster than gdb alone?

(It wasn't clear to me until I followed a few links - I hadn't heard of rr.)

[lambda]

Yes, I meant faster than gdb's native record and replay feature.

The nice thing about rr is that you can still use it with gdb, so you have the full power of gdb along with close to native speed record and reply. Once the x86-64 support is ready, it'll probably be a common tool for me.