Re: Your opinion needed: Should GNU Parallel ignore, kill or wait for background children?

[Martin d'Anjou]

Do not leak processes. In the simple case, it is as bad as leaking 
memory, and worst, the leaked process may monopolize external resources 
like files, or a database, etc.

I expect GNU Parallel to wait until everything it has started also has 
completed, and I also expect GNU Parallel to return a non-zero exit code 
if one of the processes it launched returned a non-zero.

If you don't want to wait for GNU Parallel, then backgroud GNU Parallel 
itself, and hold on to that PID if you want, but do not let children 
leak to the OS by default.

GNU Make, which has a parallel feature, does not leak processes. GNU 
Parallel should not leak either.

Martin

On 16-05-23 06:46 PM, Ole Tange wrote:
> Should GNU Parallel ignore, kill or wait for background children?
>
> Example:
>
> $ parallel '(sleep 100) & echo' ::: 1
> 1
> $ ps -opid,pgrp,cmd
>      PID    PGRP CMD
>   915719  915719 /bin/bash
>   937618  937617 sleep 100
>   937620  937620 ps -opid,pgrp,cmd
>
> The sleep is put in the background. The echo finishes, and GNU
> Parallel exits, while the sleep is still running.
>
> Is this what you expect?
>
> Or do you expect GNU Parallel to wait for the background job? Should
> it do that for every job? Or just when GNU Parallel is about to exit?
>
> Or do you expect GNU Parallel to kill the background job? Should it do
> that for every job? Or just when GNU Parallel is about to exit?
>
>
> /Ole