Python open a named pipe == hanging?

[Alex Martelli]

Donn Cave <donn at u.washington.edu> wrote:
   ...
> > You forgot to add os.mkfifo(f) here -- so you're writing and reading a
> > perfectly ordinary file... of course *that* gives no problems!-)
> 
> Of course you're right about that, and with that fixed we
> see that you're right, the open blocks.  In order to avoid
> that, you have to open "r+", which after all is what the
> original post proposed to do.

...and produces "undefined behavior" according to the manpage.

> involved.  On NetBSD, when the child process closes the write
> descriptor, that operation doesn't entirely succeed and the file
> descriptor is left in a `no more information' state.  On Linux,
> one doesn't see that, but the result is the same.  In any case, a
> stream that can't have an end is not going to be very satisfactory.
> [I don't know why I get tangled up in these named pipe problems,
> when I know better myself than to use them!]

I have no problems using named pipes _according to their documentation_
(so, in particular, no O_RDWR opening, and acceptance of their
thread-blocking behavior on O_RDONLY and O_WRONLY opening; I have no
experience with opening named pipes in non-blocking mode).


Alex