which exception do you get when you os.write() to a pipe that has nothing reading it?

[Gribouillis]

i'm thinking i need to go back and do some stuff in C, again, just to get my brain thinking about the system.

I wonder if the problem is not related to PEP 475, the fact that a system call which fails with EINTR is automatically retried by the standard library wrappers such as os.write() without raising an exception.

If this is the problem, you could perhaps give your program a chance to handle it by setting a signal handler, perhaps to catch signal.SIGPIPE.

signal.SIGPIPE
Broken pipe: write to pipe with no readers.

Default action is to ignore the signal.

Availability: Unix.