Reassign or discard Popen().stdout from a server process

John O'Hagan research at johnohagan.com
Thu Feb 10 09:35:24 CET 2011


On Wed, 9 Feb 2011, Nobody wrote:
> On Fri, 04 Feb 2011 15:48:55 +0000, John O'Hagan wrote:
> > But I'm still a little curious as to why even unsuccessfully attempting
> > to reassign stdout seems to stop the pipe buffer from filling up.
> 
> It doesn't. If the server continues to run, then it's ignoring/handling
> both SIGPIPE and the EPIPE error. Either that, or another process has the
> read end of the pipe open (so no SIGPIPE/EPIPE), and the server is using
> non-blocking I/O or select() so that it doesn't block writing its
> diagnostic messages.

The server fails with stdout=PIPE if I don't keep reading it, but doesn't fail 
if I do stdout=anything (I've tried files, strings, integers, and None) soon 
after starting the process, without any other changes. How is that consistent 
with either of the above conditions? I'm sure you're right, I just don't 
understand.

Regards,

John



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