freebsd stable - Dec 2004 - Unkillable zombie sshd-s?

I found out today that I have two zombie sshd processes on a busy server 
(dozen or so users over ssh, many other services), and I can't kill them.

sshd    38653  0.0  0.0     0    0  ??  Z    Mon08AM   0:00.03 <defunct>
sshd    75851  0.0  0.0     0    0  ??  Z     7:33PM   0:00.08 <defunct>

kill -9 doesn't complain, but doesn't do the job either.

Is there a way to find out what has happened and why does the situation 
occur? (I can't reboot the server for testing)

> I found out today that I have two zombie sshd processes on a busy server 
> (dozen or so users over ssh, many other services), and I can't kill
them.
> 
> sshd    38653  0.0  0.0     0    0  ??  Z    Mon08AM   0:00.03
<defunct>
> sshd    75851  0.0  0.0     0    0  ??  Z     7:33PM   0:00.08
<defunct>
> 
> kill -9 doesn't complain, but doesn't do the job either.
> 
> Is there a way to find out what has happened and why does the situation 
> occur? (I can't reboot the server for testing)
	You can't kill them because they are already dead.  They
	are just holding state so that the parent process can know
	how they died.  Once the parent process wait()'s on them
	(or the parent dies) they will disappear.

	This is a FAQ that is over 20 years old.

	Mark
--
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews@isc.org

Ronald Klop wrote:
> On Thu, 02 Dec 2004 15:06:21 +0100, Ivan Voras <ivoras@fer.hr> wrote:
> 
>> Can I find out what their parent processes are? (something like  
>> tree-shaped ps?)
> 
> 
> /usr/ports/sysutils/pstree
> 
> and ps can display the ppid (parent pid).
Thanks, parents were stuck and had to be killed.