intermittent ValueErrors from subprocess

[Chris Angelico]

On Mon, May 16, 2016 at 8:32 AM, Pavlos Parissis
<pavlos.parissis at gmail.com> wrote:
>> Searching the CPython sources for that exception shows one hit:
>> selectors.py, where it converts a file object to an integer file
>> descriptor. (You could have helped out by showing us the full
>> traceback.)
>
> I did, https://gist.github.com/unixsurfer/67db620d87f667423f6f6e3a04e0bff5

Ah. I didn't click that link in your original post - didn't know it
was the traceback. Better would have been to at least say so; best
would have been to include it inline.

>> Is it possible you were running out of file descriptors,
>> or in some other way unable to create the pipe?
>
> I don't think as I see right now only 8 FDs:
>
> sudo ls -1 /proc/22706/fd|wc
>       8       8      16
>

If you can recreate the problem consistently, it would be worth
messing around with slightly lower level APIs - using subprocess.Popen
rather than check_output, for instance - and see what you can do
without the pipes. Somewhere, something's failing, and it's not easy
to see what.

ChrisA