kill pid is not working? [duplicate]

Question

This is pretty weird now. I am trying to kill a process by using its pid but it is not working at all.

root@machineA:/home/david# ps aux | grep modelling
david  5075  0.0  0.0 1285420 29404 ?       Dl   21:05   0:01 /opt/modelling/bin/http
root   8730  0.0  0.0   8096   936 pts/4    S+   22:43   0:00 grep --color=auto modelling

Below is the way I am kiiling the process.

root@machineA:/home/david# kill -9 5075

And then if I do the ps again. I can see the same result back again.

root@machineA:/home/david# ps aux | grep modelling
david  5075  0.0  0.0 1285420 29404 ?       Dl   21:05   0:01 /opt/modelling/bin/http
root   9062  0.0  0.0   8100   936 pts/4    S+   22:44   0:00 grep --color=auto modelling   

Does anyone know what is happening? This was working fine earlier and it has started happening few hours back and I am not sure what's wrong?

Update:-

I did top and it is showing as D instead of Z which is uninterruptible sleep

5075 david  20   0 1255m  28m  13m D    0  0.0   0:01.09 http

Answer 1

To remove a D State Process, since it is uninterruptible, only a machine reboot can solve the problem in case its not automatically handled by the system.

Usually there is a very few chance that a process stays in D State for long. And if it does then there is something not properly being handled in the system. This can be a potential bug as well.

Below is an extract from OpenVZ about what is D State of a process.

D state occurs then the process is in uninterruptible sleep. This state is bad, because you can't do anything with the process in D state. Fortunately, process normally remains in such state not for so long. But if you have a heap of D state processes then some logic in system is disrupt. If that is happening, the very important thing is to determine where this unlucky sleep occurs. It is easy to do with ps command with l option. WCHAN column shows the name of the kernel function where the process is sleeping:

# ps axl | awk '$10 ~ /D/'
F   UID   PID  PPID PRI  NI    VSZ   RSS WCHAN  STAT TTY        TIME COMMAND
vass     13478  7.2  0.0   1732   624 pts/1    D+   17:36   0:00 find ./

[Refernce] - https://openvz.org/Processes_in_D_state