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killing defunct processes

Posted on 2002-04-15
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How can I kill a defunct process without rebooting and when I get the following message after trying to kill it : "no such process"?
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Question by:dgiessen
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by:griessh
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How do you try to kill the process.

Do a "ps -aef | grep <processname>" (or whatever your ps options are) and if you have the right you should be able to "kill -9 <PID>".

Are you the owner of the process of at least in the group that owns the process?

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Werner
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by:ahoffmann
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depends on your UNIX.
AFAIK not possible for SunOS, SOlaris, Irix, Linux, OSF
Not shure about AIX and HP-UX
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by:chris_calabrese
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It's not possible on any UX system, including AIX and HP-UX.

On the other hand, defaunct processes are already dead, so there's really nothing to kill.

They just exist in the process tables because their parent process has not reaped them yet.

So, to directly anser the question, killing the parent will do the trick.
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by:ahoffmann
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> .. killing the parent will do the trick.
hmm, for deamons the parent is 1. It's also 1 if the parent died before.
So killing *this* parent (init) is a more crude way to do a reboot ;-)
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by:griessh
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now I am confused ... I didn't get the feeling he is talking about a zombie process ...

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Werner
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by:chris_calabrese
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ahoffman - init will reap its children, so this should be a non-issue.

griessh - interesting comment.  I was picking up on the 'defunct' bit.  I _think_ the 'no such process' message sounds like a defunct process, but I'm not 100% on this.

dgiessen - are these 'defunct' processes according to 'ps'?
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by:dgiessen
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When I run ps -fu userx I get a listing showing a number of processes with various PID #'s, all associated with one PPID # and the CMD = <defunct> (for all).

If I run "kill 12345" (as root), I get "kill: 12345: no such process" ( a kill -9 12345 gives me the same result).

Seeing all the defunct processes out there is bad enough, but I also cannot log in under my ID because due to all the defunct processes, I'm getting an error at login saying "...max_proc_per_user (=64) exceeded..."

By the way, the OS is AIX.
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by:chris_calabrese
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Yup, those are genuine defunct processes alright.

You need to kill the parent.
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by:ahoffmann
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defunct processes cannot be killed anyhow, they are dead and alife ('til the parent removes them) --> zombie

> max_proc_per_user
can be changed with smitty
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by:griessh
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Do you have an idea where those processes come from? I'm just curious, since I haven't seen more than 10 zombies on my AIX box since I'm working on it ...

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Werner
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chris_calabrese earned 10 total points
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They're caused by the process exiting but the parent never reaping them with the wait() family of system-calls.  Most likely you've got a program someone at your site wrote in C that fork()s a bunch of children and doesn't catch the SIG_CHLD signal that says one of them exited (and then you can call wait() in the signal handler...)
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by:griessh
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chris

thanks for the reply. My question was actually for dgiessen ... I was curious if he is running some special software there.

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Werner
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by:chris_calabrese
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Oops, I was rifling through my mails and though the question was from dgiessen.

In that case, I second your question...
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by:dgiessen
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The only two "programs" associated with this particular user id are Cognos Impromptu report writer (which is run on a seperate Windows 2000 server) which accesses an Informix database on the AIX box and MS Access connecting from a Windows PC via ODBC to the same Informix database. Each application uses Informix ODBC drivers and seems to spawn the zombie processes.

When connecting through Access/ODBC, it spawns 1 process, regardless of how many times I reconnect to different databases within Informix. Through Cognos, I spawn 1 process for each different database I connect to.

At this point I'm also looking into how to get ODBC to cleanly close a table connection and not leave zombie processes and I'm trying to work with Cognos on the same issue.
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by:tfewster
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No comment has been added lately, so it's time to clean up this Topic Area.
I will leave a recommendation for this question in the Cleanup topic area as follows:

- Answered by chris_calabrese

Please leave any comments here within the next 7 days

PLEASE DO NOT ACCEPT THIS COMMENT AS AN ANSWER !

tfewster (I don't work here, I'm just an Expert :-)
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by:modulo
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Finalized as proposed

modulo

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