Light (general) Inter-Process Mutex/Wait/Notify Synchronization?

[Gunter Henriksen]

> If you don't want to use a 3rd party module you could
> use the multiprocessing module

That is definitely good for when I have a tree of
processes which are all Python applications.  I use
it for that.  But I am looking for something where
the Python application can interact conveniently
with an arbitrary external application.  Using a
socket/pipe and shared memory is convenient, but
not feasible when system call overhead matters.