Another thing I didn't do in this patch yet: I feel we should replace BackendPidGetProc() with a function like "PGPROC *PidGetPGProc(pid_t)", that would work for backends and aux processes alike. It's a common pattern to call BackendPidGetProc() followed by AuxiliaryPidGetProc() currently. Even for the callers that specifically want to only check backend processes, I think it would be more natural to call PidGetPGProc(), and then check the process type.
+1 for the idea, do you also intend to remove AuxiliaryPidGetProc() as part of this change, given that all the occurrences of it are coupled with BackendPidGetProc() ?
