subprocess call is not waiting.

[MRAB]

On 2012-09-13 16:17, paulstaten at gmail.com wrote:
> I have a subprocess.call which tries to download a data from a remote server using HTAR. I put the call in a while loop, which tests to see if the download was successful, and if not, loops back around up to five times, just in case my internet connection has a hiccup.
>
> Subprocess.call is supposed to wait.
>
> But it doesn't work as intended. The loop quickly runs 5 times, starting a new htar command each time. After five times around, my program tells me my download failed, because the target file doesn't yet exist. But it turns out that the download is still happening---five times.
>
> When I run htar from the shell, I don't get a shell prompt again until after the download is complete. How come control is returned to python before the htar command is through?
>
> I've tried using Popen with wait and/or communicate, but no waiting ever happens. This is troublesome not only because I don't get to post process my data, but because when I run this script for multiple datasets (checking to see whether I have local copies), I quickly get a "Too many open files" error. (I began working on that by trying to use Popopen with fds_close, etc.)
>
> Should I just go back to os.system?
>
Which OS? Is there some documentation somewhere?