Why defunct process are created?Ans : When ever a process ends all the memory used by that process are cleared and assigned to new process but due to programming errors/bugs some processes are still left in process table. These are created when there is no proper communication between parent process and child process.
Some FAQ?
1. How to find a defunct process?
And : Grep defunct value in ps -ef output#ps -ef grep defunct
2. How can i kill a defunct process?And : Just use kill command#kill defunct-pid
3. Still not able to kill?
Ans : Then use kill -9 to force kill that process
#kill -9 defunct-pid
4. Still have an issue in killing it?
Ans : Then try to kill its parent id and then defunct.
#kill parent-id-of-defunct-pid
Then
#kill -9 parent-id-of-defunct-pid
5. Still having defunct?
Ans : If you still find defunct process eating up RAM then last and final solution is to reboot your machine.
6.What is orphan process?
Ans : An orphan process is said to be a process which runs though parent process is terminated, these process do not know what to do and when to terminate.
7. What is difference between orphan and defunct processes?Ans : A defunct process is a dead process where there is no execution happening where as orphan process is a live process which is still in execution state but don’t have parent process
I am having a system which daily creates defunct process, I cannot sit and kill these process on daily basis.
How to get rid of this problem?Ans : Just write a shell script to grep defunct process and kill them by putting this script in corntab.
Kill all process:
- #ps ax -o user,pid |grep 'postfix' |awk '{print $2}' |xargs -l
- #ps ax -o user,pid |grep 'postfix' |awk '{print $2}' |xargs -r kill -9
- #killall -9 PROCESS
REFERENCES
http://www.linuxnix.com/2010/05/how-to-kill-defunct-or-zombie-process.html
