topic Re: Best way to locate and kill a zombie in Operating System - HP-UX

Best way to locate and kill a zombie

John Jimenez — Thu, 20 Feb 2003 17:21:12 GMT

While running top, there is one zombie running. What is the best way to locate this "PID", so I can kill it?

Re: Best way to locate and kill a zombie

Ralph Grothe — Thu, 20 Feb 2003 17:25:19 GMT

I'm afraid, I think you won't be able to kill, because the Zombie is waiting for its parent process to fetch its exit code through a wait() or waitpid() syscall by the parent.

However, you can get the PID from the process table if you grep for the string "defunct"

e.g.

ps -ef|grep defu

Re: Best way to locate and kill a zombie

Sridhar Bhaskarla — Thu, 20 Feb 2003 17:25:39 GMT

Do a "ps -ef|grep defunct".

-Sri

Re: Best way to locate and kill a zombie

Patrick Wallek — Thu, 20 Feb 2003 17:32:39 GMT

top shows the PIDs of processes. The 3rd column of the top output is the PID. However, it the process truly is a zombie, then you probably won't be able to kill it. Why? BECAUSE IT'S ALREADY DEAD!!!! To quote from an HP Performance expert.

Re: Best way to locate and kill a zombie

Helen French — Thu, 20 Feb 2003 17:42:46 GMT

You can find out the PID from top itself or from grep' ing with 'defunct. But you cannot kill those processes since it's already dead. The best way to get rid of those processes is to reboot the system!

Re: Best way to locate and kill a zombie

John Jimenez — Thu, 20 Feb 2003 17:42:57 GMT

Thanks, I greped "defun" and it found it.
# ps -ef | grep defu
root 3047 2718 3 Feb 15 ? 0:00
root 9189 969 0 09:39:11 ttyvb 0:00 grep defu

It has actually been a long time since I have seen a zombie. As I remember I thought that I can just kill this "PID"? if not how would I get rid of it?

Re: Best way to locate and kill a zombie

John Jimenez — Thu, 20 Feb 2003 17:45:52 GMT

Okay, I will not worry about it, I will just let the reboot take care of it. thanks a lot....

Re: Best way to locate and kill a zombie

melvyn burnard — Thu, 20 Feb 2003 17:46:42 GMT

Sorry to dissappoint you, but he only way to get rid of a zombie process is to rebot.
You cannot kill what is already dead.
In the words of John Cleese, from hte pqrrot sketch in Monty Python:
It is an ex-parrot, it has ceased to be, it is no more.
It's DEAD

Re: Best way to locate and kill a zombie

Helen French — Thu, 20 Feb 2003 17:46:54 GMT

Read this for more information about defunct processes TKB #S1100000464:

http://support2.itrc.hp.com/service/cki/docDisplay.do?docLocale=en_US&docId=200000063236571

Re: Best way to locate and kill a zombie

Pete Randall — Thu, 20 Feb 2003 17:50:45 GMT

John,

What is the parent process? Do a "ps -ef |grep 2718". I would have expected a zombie to be owned by init (PID 1).

Pete

Re: Best way to locate and kill a zombie

Sridhar Bhaskarla — Thu, 20 Feb 2003 17:53:19 GMT

Hi John,

It is still not a real zombie as it's parent it not yet "1", init - the God mother of all processes.

Now try "ps -ef|grep 2718" and see what process is listed?.

A zombie that is attached to init, cannot be killed. They are ghosts waiting to send their status information to their parents that do not exist. So, a good programmer can write a code that will get the status from the waiting child. Once the status is reported, the child will literally die.

If the zombies are not talking too much of CPU (sometimes users report that the defunct process is consuming too much CPU, by misunderstanding how Glance reports), then I will wait for my next maintenance window.

-Sri

Re: Best way to locate and kill a zombie

John Jimenez — Thu, 20 Feb 2003 17:58:07 GMT

# ps -ef |grep 2718
root 2718 1 0 Feb 15 ? 0:00 /opt/perf/bin/perflbd
root 3047 2718 3 Feb 15 ? 0:00
root 2733 2718 0 Feb 15 ? 0:57 /opt/perf/bin/rep_server -t SCOo
root 10180 969 2 09:54:37 ttyvb 0:00 grep 2718

Yes it looks like the parent is "1". it does taking any proccessing, but if I have time I will try and find a script, just in case one pops up in the future that does take up processing time. thanks again....

Re: Best way to locate and kill a zombie

Pete Randall — Thu, 20 Feb 2003 18:08:10 GMT

John,

The point is that if the parent is not init (PID 1), the "zombie" can be killed by killing off the parent (in your case 2718). I'm not sure what perfldb is and therefore, I'm not sure this is something you want to do, but it's something to remember for next time.

Pete

Re: Best way to locate and kill a zombie

Sridhar Bhaskarla — Thu, 20 Feb 2003 18:13:43 GMT

If you can afford to stop Measureware on your system, do a mwa stop and see what happens by running ps -ef. That should stop perflbd process. You can do a mwa start later to start that process.

This may probably make it a real zombie. If you are lucky, then it may kill it too.

-Sri

Re: Best way to locate and kill a zombie

Marco Santerre — Thu, 20 Feb 2003 18:18:19 GMT

perflbd is part of your MeasureWare software. So to try and kill you rdefunct process I would suggest to try and stop MeasureWare and restart it. That way the paretn process will stop and hopefully terminate its child too.

/sbin/init.d/mwa stop
/sbin/init.d/mwa start

Re: Best way to locate and kill a zombie

John Jimenez — Thu, 20 Feb 2003 18:26:34 GMT

Yes I figured where this came from a few minutes ago. I installed the diagnostic tools over the weekend and had some problems because I did not stop measureware while doing swinstall the first time.

Awesome stopping and starting measureware again did the trick, the zombie disapeared... :)