The problem here is when you have more than 2, and especially as it combinatorially expands as you get more and more locks. Now I need Lock A, Lock C, and Lock

The problem here is when you have more than 2, and especially as it combinatorially expands as you get more and more locks. Now I need Lock A, Lock C, and Lock F, but then this other critical section needs Lock A, Lock D, and Lock F, and if you are encapsulating then you start needing a whole lot of different functions for all the different combinations, and have to make sure that all are consistent. I've got multi threaded C++ in production right now, and it is because the code is small and avoids multiple locks that I have any faith in it. As a code base expands, in kloc and in time, this gets harder and harder to reason about.