subprocess.Popen hangs at times?

[Christian Heimes]

Kenneth McDonald wrote:
> When making calls of the form Popen(cmd, shell=True, 
> stdout=subprocess.PIPE), we've been getting occasional, predictable 
> hangs. Will Popen accumulate a certain amount of stdout and then block 
> until its read? We don't want to use threads, so just want to read the 
> entire stdout after the subprocess has finished.

The subprocess module has already an API method for your use case. The 
communicate() method of a subprocess.Popen instance takes an optional 
stdin string and returns the stdout and stderr output as strings. The 
method uses the best low level functions possible (select() on Unix, 
threads on Windows).

Christian