Visit Our UNIX and Linux User Community

How to clear defunct processes??

Thread Tools Search this Thread
Operating Systems HP-UX How to clear defunct processes??
# 1  
Old 01-09-2013
How to clear defunct processes??

How to find out and clear the 'defunct' processes at OS and DB level ..??
# 2  
Old 01-09-2013
It's not the system that's letting them accumulate, it's whatever program creating them that is. They still belong to a living process, one which hasn't called wait() for them. That's a bug.

If you restart that daemon, causing it to quit and reload, those zombie processes will default their ownership back to INIT, which will handle them properly.
# 3  
Old 01-09-2013
Originally Posted by SurajR
How to find out and clear the 'defunct' processes at OS and DB level ..??
You get a defunct process (or zombie) when that process exits and its parent does not gather its exit status (see the man page for the wait() system call). If, and only if, the parent exits before its children's exit status is collected, a system process (usually named init) will gather the exit status of abandoned children.

This is the way it works on any UNIX or Linux system, not just HP/UX.

Last edited by Don Cragun; 01-09-2013 at 03:22 PM.. Reason: clarification
# 4  
Old 01-09-2013
PS: you cannot use
kill -9

on a defunct (zombie) process, because the process is already dead.

The name zombie comes from those cheap 1960's movies like 'Day of the Dead' - except in those movies you could apparently 'kill' those zombies.... you cannot kill something that is already dead in UNIX, it ain't the movies.
These 3 Users Gave Thanks to jim mcnamara For This Post:
# 5  
Old 01-09-2013
I have a question: You mentioned that the zombie process is already dead. But this process entry remains in the process table. I read somewhere that the problem would grow serious under heavier loads and OS may run out of Process ID numbers! Is this situation possible or does init invokes wait system call all the time and reap any zombies?
# 6  
Old 01-09-2013
Zombies remain in the process table for a reason: There's still information there about how the program quit, which their parent is supposed to get via the wait() or other related calls. Once it does, they're deleted from the table.

init can't wait for processes that don't belong to it. If it did, that could cause problems with processes that were handling their children -- if init handles the dead process first for whatever reason, the proper parent will be stuck waiting for it.

So, only the owner of a process is allowed to wait() for it.

So a process that accumulates an endless amount of zombies is a serious problem. There may be limits in place preventing one user from running too many simultaneous processes, but often these limits haven't been specified for daemons. It's possible for the process table to be filled up, yes.

The proper way to deal with zombies is to fix the bug in the program that's allowing zombies to accumulate. The short-term solution is to kill their parent -- all the zombies will default back to init, which will clean them up.

Last edited by Corona688; 01-09-2013 at 06:37 PM..
This User Gave Thanks to Corona688 For This Post:
# 7  
Old 01-10-2013
In HP-UX zombie processes which are waiting for a hardware resource will not die without a reboot.

Can you post an example process tree?
How many zombie processes do you have on a bad day? Do they ever disappear without a reboot?
What database engine are you using, and do you have a simple explanation for the zombie processes (like users disconnecting untidily)?
This User Gave Thanks to methyl For This Post:

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. HP-UX

Defunct Processes; Maximum Process

I'd like to remove this defunct processes without rebooting. Or, I could remove this defuncts when the maximum allowable process is nearly reached, then send an email to the user/team. How can I determine the maximum allowable process that a server can handle? Any thoughts? Jin@PRODUCTION: >... (3 Replies)
Discussion started by: Jin_
3 Replies

2. UNIX for Advanced & Expert Users

defunct processes?

HiI had a tool fail recently, on analysis I found it was cleaning up orphaned directories that had been created by specific processes that had died for some reason, thus failing to clean up after themselves.The directories were of the form / The tool would look to see if any instances of... (2 Replies)
Discussion started by: steadyonabix
2 Replies

3. HP-UX

Defunct processes are getting generated

Dear Sir / Madam, We have two socket programs which are running in background. These two socket programs are creating defunct processes in HP-UX which were not happening in Compaq True64 UNIX. What is the root cause of these defunct processes and how can we correct it? Your suggestion will be... (3 Replies)
Discussion started by: kcsahoo
3 Replies

4. Shell Programming and Scripting

Abnormal behaviour of Defunct processes.

Hi All, Sorry to bother you all if my query is silly. Can you please clarify my doubts on defunct processes. Actually coming to the scenario, i have a server which is under cluster environment. Server B is having problems with the defunct process. There was a cron scheduled on Server B which... (0 Replies)
Discussion started by: reddybs
0 Replies

5. Programming

defunct vs running

hello everybody! Is there any way to identify if a process is defunct or if it is still running? (in C). for example: by using a signal such as SIGCHLD? thanx in advance (1 Reply)
Discussion started by: nicos
1 Replies

6. AIX

Defunct Processes

Hi, Can any one help me to get rid of defunct process on UNIX IBM AIX box. These processes started when the system was rebooted almost after 1 1/2 years. Once one defunct process is created then all the user ids get infected and in turn creates numerous defunct processes. We have tried... (6 Replies)
Discussion started by: trokia88
6 Replies

7. UNIX for Dummies Questions & Answers

whats the difference between zombie orpha and defunct processes

can some one please explain zombie orphan defunct and how they r related (3 Replies)
Discussion started by: pbsrinivas
3 Replies

8. UNIX for Dummies Questions & Answers

Question about defunct processes

Hey guys/gals. I am new to the site and fairly new to Unix/Linux. I have a master netbackup server (solaris) that I get pinged on occasionally regarding defunct processes. (Usually over 50 or so of them.) I know what a defunct process is, but what is it a product of? Just plain sloppy code? (From... (1 Reply)
Discussion started by: EMCSANMAN
1 Replies

9. Solaris

how do I kill defunct processes?

mqm 17700 16815 0 0:00 <defunct> kill -9 does not work, even as root (10 Replies)
Discussion started by: csaunders
10 Replies

10. UNIX for Dummies Questions & Answers

<DEFUNCT> Processes

When I ps -ef I see about 3 or 4 <DEFUNCT> things - what are these, and what causes them? Are they a concern? How can I fix them? Thanks, Michael (4 Replies)
Discussion started by: cuppjr
4 Replies

Featured Tech Videos