Help me, there is a zombie process!

Here Show archive.org snapshot is a good explanation for zombie processes.

Quote:

CopyIf you have zombie processes it means those zombies have not been waited for by their parent (look at PPID displayed by ps -l). 
You have three choices: Fix the parent process (make it wait); kill the parent; or live with it.
Remember that living with it is not so hard because zombies take up little more than one extra line in the output of ps.

On a server I want to get informed if there are zombie processes and track them with a Icinga check. That's the reason why I want to get rid of them.

Example to get rid of the zombies (in this example there are some python zombie processes):

1. Get PPID of zombie process:

   Copy $ ps -ef | grep "python"
    [...]
    nova     13930  1543  0 Jun19 ?        00:00:00 [python] <defunct>
    nova     13931  1543  0 Jun19 ?        00:00:00 [python] <defunct>
    nova     13932  1543  0 Jun19 ?        00:00:00 [python] <defunct>
    nova     13933  1543  0 Jun19 ?        00:00:00 [python] <defunct>
    nova     13934  1543  0 Jun19 ?        00:00:00 [python] <defunct>
    nova     13935  1543  0 Jun19 ?        00:00:00 [python] <defunct>
    # PPID of all the zombie processes is 1543
   

2. Find the Parent process:

   Copy $ ps -ef | grep 1543
    [...]
    nova      1543     1  0  2012 ?        00:19:37 python /usr/bin/nova-novncproxy --flagfile=/etc/nova/nova.conf --web /usr/share/novnc/
   

Now you have the two choices, fix it or kill it. In this case it's no critical service and I can just restart it.