Re: Hang issue when COPY to/from an unopened FIFO

* Tom Lane (tgl(at)sss(dot)pgh(dot)pa(dot)us) wrote:
> Kenan Yao <kyao(at)pivotal(dot)io> writes:
> > -- mkfifo /tmp/test.dat # bash
> > copy pg_class to '/tmp/test.dat';
> > -- try pg_cancel_backend or pg_terminate_backend from other sessions
>
> This does not seem like a supported case to me. I see few if any reasons
> to want to do that rather than doing copy-to-program or copy-to-client.
> We're certainly not going to want to add any overhead to the COPY code
> paths in order to allow it.

The complaint is that there's no way to safely kill a process which has
gotten stuck in a fopen() call. I sympathize with that point of view as
there are many ways in which a process could get stuck in a fopen() or
similar call and it would be nice to have a way to kill such processes
without bouncing the entire server (though I wonder if this is a way to
end up with a dead backend that sticks around after the postmaster has
quit too, which is also quite bad...).

Thanks!

Stephen