topic Re: process zombie in Operating System - Linux

process zombie

Manuel_5 — Wed, 10 Sep 2003 21:21:57 GMT

Hi to all,
As I kill processes zombie?

Manuel,

Re: process zombie

Steven E. Protter — Thu, 11 Sep 2003 00:06:35 GMT

kill -9 PID

PID is process id

If that does not work, then reboot the box.

SEP

Re: process zombie

twang — Thu, 11 Sep 2003 01:38:05 GMT

Hi Manuel,

It seems that you need to reboot your system to remove those processes zombie, but if you cannot reboot it now, it should not cause you too much trouble until downtime can be arranged.

best regards
twang

Re: process zombie

Mark Grant — Thu, 11 Sep 2003 06:46:26 GMT

A zombie process is a process that has finished execution but whose parent has not issued a "wait()"

The zombie process will go away as soon as the parent process does the "wait()". If they are staying around for a while, then you have an application that is not behaving properly and you should try and investigate which one it is.

It is worth pointing out that unless you get lots and lots of these, they aren't taking up resources.

Re: process zombie

Yu Wang_1 — Thu, 11 Sep 2003 12:00:50 GMT

No. You don't have to reboot your box for getting rid of the zombies. Here are steps:

-get pid of the zombie (defunc);
-then ps -elf|grep pid. This will show parent and/or child(ren) process of the zombie.

-if the zombie's parent process is 1 (init), there must be at least one child process belongs to this zombie. From above ps command, you will see the pid of the child process.
Use kill -9 childpid. Then the zombie would go away.

-if the zombie's parent process is not 1, then you need use ps to grep the parent process. If there are no more other child processes running under the parent process, use kill -9 parentpid. then the zombie would go away. But if the parent has other child running, you might want to be careful in that killing parent may terminate those child processes as well.

I came out this method and use it in my system frequently and it works just perfect.

Hope this helps.

Re: process zombie

Stuart Browne — Fri, 12 Sep 2003 03:03:22 GMT

Whilst what Yu mentioned are good steps for clean-up, it won't necessarily fix things.

If it is a true zombie process who's parent has died (as Mark talked about), then you won't be able to kill it, and as Steven and Twang said, a reboot will be required.

If a process has gone truely gone zombie, there is nothing you can do.

Re: process zombie

Glen Trevino — Fri, 12 Sep 2003 03:14:36 GMT

Re: process zombie

Andrew Bruce — Mon, 22 Sep 2003 04:13:27 GMT

So, to sum up ;-)

A you cannot kill a zombie as it is already dead. That is why it is called a zombie!

The zombie hangs around *purely* as an entry in your process table. This is so that it can report its exit code, CPU time, and a few other stats back to the parent process that initiated it.

If the parent process has died off without wait()ing for the exit status, etc., then the zombie may well be orphaned and cannot be removed by any means other than a reboot.

However, as I said earlier, it is only taking up one slot in your process table - it doesn't consume memory, or CPU (pre se), so the only side effect of a zombie process lingering is that, if you find processes spawning a large number of zombies, you will eventually run out of process space and your computer will fall over.

Zombies are generally the result of poorly written software.

Hope this helps (HTH).

B.

ps A quick search on google would have answered this and more, more quickly! ;-)