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Date: Sat, 26 Jul 2008 13:16:13 -0400
From: Jason Tishler <jason AT tishler DOT net>
Subject: Re: cygwin python: subprocess.Popen().stdout + threads == hang
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Charles,

On Thu, Jul 24, 2008 at 12:11:46PM -0400, Charles Wilson wrote:
> Ran into a weird issue using python on cygwin. When trying to use the
> stdout handle from a subprocess spawned using the subprocess.Popen
> class, it hangs when accessed via a thread. This behavior does /not/
> occur on other platforms -- nor when using os.popen from threads on
> cygwin. Nor when using subprocess.Popen from cygwin without threads.
> 
> [snip]
> 
> I've attached a test case to demonstrate the issue. I was hoping (a)
> somebody has seen this before, and has a simple solution for me, or
> (b) the python maintainer (Jason?) could take a look, and maybe raise
> a bug report upstream.

As my README indicates, Cygwin Python has some pthreads-related issues.
Given that you don't observe this behavior on other platforms, it seems
like this is a Cygwin specific problem.  So, I don't think raising an
upstream bug report will help.

I would like to help with this problem, but my expectation is it will
take many hours or days to debug.  I've been in the Cygwin and Python
pthreads-related code before and it is not a fun place to be. :,)
Sorry, but the reality is I don't have the time to help with a problem
of this difficulty.

Jason

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