[plug] zombie GDM processes

[James Devenish]

In message <3F3C4A51.6020805 at postnewspapers.com.au>
on Fri, Aug 15, 2003 at 10:49:53AM +0800, Craig Ringer wrote:
> Has anybody on [plug] seen GDM processes go zombie before? I just had my 
>  GDM server stop responding to XDMCP connections and go zombie while 
> still holding the listen socket on the XDMCP port. Of course, you can't 
> kill a zombie process (WHY?!?) so it was reboot time... *sigh*.

Zombie processes don't really exist (it's just that the parent process
hasn't received the appropriate signals to indicate that its child has
died) -- was the parent process okay (let's hope it wasn't `init`!).
Linux *does* have an "unkillable" process state, which I suppose must be
a "necessary evil" in the kernel design. Unkillable processes require a
reboot, but I don't think zombie processes should have any impact on
your system unless there is "another problem".

> Also, if there's any way to force a zombified daemon to release a 
> socket, I'd love to hear about it.

This sounds like a bug...how can a zombie process be using any
resources...the process doesn't exist! Off the top of my head all I can
think is that either (a) the parent process is having some part to play
in this or (b) there is a kernel bug.