Python's subprocess.Popen object hangs gathering child output when child process does not exit

Question

When a process exits abnormally or not at all, I still want to be able to gather what output it may have generated up until that point.

The obvious solution to this

Answer 1

I had the exact same problem. I ended up fixing the issue (after scouring Google and finding many related problems) by simply setting the following parameters when calling subprocess.Popen (or .call):

stdout=None

and

stderr=None

There are many problems with these functions but in my specific case I believe stdout was being filled up by the process I was calling and then resulting in a blocking condition. By setting these to None (opposed to something like subprocess.PIPE) I believe this is avoided.

Hope this helps someone.