[nzlug] can not kill a process

[Michal Ludvig]

Rex Johnston wrote:
> anru chen wrote:
> 
>> i have a process that can not be killed even by use kill -9 pid.
> 
> They are call zombies.  Stuck waiting for the kernel in a system call.

Processes waiting in a system call are in state D - it's a normal state,
e.g. for processes doing heavy I/O on the disk. Having too many
processes in D state usually means your system is overloaded, disks are
too slow or even there could be a problem with the disks (IO errors, etc).

Zombies are in state Z - that means that they exited but their parent
haven't yet checked their exit status. They don't take much system
resources and are mostly harmless, but ideally you should have no
zombies in the system indeed ;-) It's often an application bug.

OTOH Anru described the process as being in state R. Strange he can't
kill it with -9. Anru: when you kill -9 <PID> and relist processes is
the PID of sendmail still the same? Or does it differ?

Michal