Popen4 -> null lines on Windows

[Patrick L. Nolan]

We have an application that works on Linux.  It has to be ported
to Windows XP, and there's one bug that's driving me crazy.
There's a number-crunching program written in C++.  It is invoked
by a Tkinter python script.  The script uses the threading
module to separate out the heavy processing.  The worker thread
uses popen4 to run the C++ program and capture its standard
output.  This output is sent to the master thread through a
queue and displayed by the gui.

As I said, it works on Linux.  On XP, every call to readline()
on the program's stdout returns only a zero-length string.
We are confident that the C++ program doesn't behave that
way.  We have tried both popen2.popen4 and win32pipe.popen4.

Does this sound familiar to anyone?

-- 
*   Patrick L. Nolan                                          *
*   W. W. Hansen Experimental Physics Laboratory (HEPL)       * 
*   Stanford University                                       *