Get partial stdout and stderr from Popen that runs indefinitely

Question

I'm building a wrapper around a server cmd line script that should run indefinitely. What I need to do is to get the current stout without waiting for the subprocess to finish.

I mean, if I run the following, everything works fine:

ls = Popen(["ls"], stdout=PIPE)
output = ls.stdout.read()

But if I do the same with an indefinitelly running program:

server = Popen(["python","-m","SimpleHTTPServer"], stdout=PIPE)
output = server.stdout.read()

It will not come back...

Update: Even

 output = server.stdout.read(1)

hangs...

Do you know if there's a way to capture partial output from a Popen (or similar threading implementation) in an OS independent way?

Answer 1

i would guess that read() returns the entire contents? If you read a fixed size chunk in a loop you may get better results.

Answer 2

See the solutions here