Proper way of re-using and closing a subprocess object

Question

I have the following code in a loop:

while true:
    # Define shell_command
    p1 = Popen(shell_command, shell=shell_type, stdout=PIPE, stderr=PIPE, preexec         


        

Answer 1

1. Depends on what you expect the process to do; you should always call p1.wait() in order to avoid zombies. Other steps depend on the behaviour of the subprocess; if it produces any output, you should consume the output (e.g. p1.read() ...but this would eat lots of memory) and only then call the p1.wait(); or you may wait for some timeout and call p1.terminate() to kill the process if you think it doesn't work as expected, and possible call p1.wait() to clean the zombie.

Alternatively, p1.communicate(...) would do the handling if io and waiting for you (not the killing).

1. Subprocess objects aren't supposed to be reused.