How can I implement a timeout with subprocess.Popen()?

[I. Myself]

I want my Python program to invoke a compiled C program, and capture the 
text output.
Here's a fragment from a program that works, using subprocess.Popen:

    p = Popen(execName, stdout=PIPE)
    while(1):
        line = p.stdout.readline() # get next line
        outfile.write(line)
        (Then I test for a certain unique phrase in line, and then break 
if it occurs)

The above works fine as long as the target program runs for a little 
while and then stops.  But what if  it does not stop?   It might run 
forever, with or without outputting any lines.  How can I make this 
robust?  The keyword might not occur.  The target might crash.  It might 
run forever, with or without text output.

Thanks,

Mitchell Timin

-- 
I'm proud of http://ANNEvolve.sourceforge.net.  If you want to write software,
or articles, or do testing or research for ANNEvolve, let me know.

Humans may know that my email address is: (but remove the 3 digit number)
zenguy at shaw666 dot ca