[codehog]

Even those are probably not 100% outside of its scope. I forget the details of chaos mode, but that kind of induced thread-switching can cause just the kind of interleaving you seem to be talking about.

What rr cannot capture is a very small subclass of race conditions involving things like cache line misses - I think that's what you're alluding to by "correct use of the memory model is paramount" but it's a subclass even of those. Yes, those are hugely difficult to diagnose and it would be fantastic if tools like rr or UndoDB could capture them. But there's a vast swathe of also very difficult race conditions that this recording tech can and does help with today.