Re: kill: cannot kill some processes
William T Wilson wrote:
>
> On Thu, 22 Feb 2001, brian moore wrote:
>
> > > does the process list "Z" under STAT ? if it is the process has gone
> > > zombied and i don't think there is much you can do. sometimes zombie'd
> > > processes die on their own eventually many times they will not die until
> > > you reboot ..
> >
> > Not quite true... zombies don't ever die: they're already dead.
>
> While the description of zombie processes is accurate, I think another
> likely situation is that the process is in "uninterruptible sleep," i.e.
> the 'D' state. This happens when a process is blocked in a system call -
> it will be 'D' until the kernel function returns. Kernel bugs, hardware
> problems, and dead NFS mounts can cause these kernel functions to take
> a long time or forever.
>
> In such a case, you really are stuck; unless the resource the process is
> waiting for frees up, it's going to hang around until a reboot.
>
> One thing about zombie process: Don't worry about trying to "make" them go
> away. They don't consume any CPU time, or any other resources other than
> the slot in the process table and the less than 1K of memory required to
> hold their state information. They are not worth worrying about.
Not entirely true. Init can inherit enough zombie processes that it
hits its process limit (1024, if I remember correctly). Can you
'shutdown'? Nope. Not unless you can free up a slot. And if
something's going haywire and spawning zombies quickly, this can be a
problem.
Not a common occurance, though...
-Ron-
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