gnomerc=Zombie

[Robert Brockway]

On Fri, 12 Nov 2004, Taavi Burns wrote:

> But it IS consuming resources: an entry in the process table.  I'm quite
> sure that I've heard of machines which required a reboot because the
> process table became full (the process table size on UNIX has
> historically been a boot- or compile-time parameter).  I don't know if
> modern Linux kernels have improved on this or not, but last time I
> checked 32-bit Linux still only used 16-bit PIDs, meaning that when you
> reach around 65534 zombies (since you need init, and I don't think PID 0

The PID is a signed 32-bit value so it wraps at 32768.

Up until sometime in 2.3 the process table was much smaller than this.
The #define NR_TASKS was set to 512 by default (128 in really old
kernels). Filling the process table with zombies could indeed ruin an
admins day.

Things are better now.  cat /proc/sys/kernel/threads-max to see the
maximum number of threads the system will allow.  This number can be
changed on the fly.  I guess there is still some upper limit.

Remember exec can come to the rescue too - it replaces one process with
another in the process table rather than creating a new process table
entry (as normally happens when you fork).  Quite a few admins have exec'd
a kill to fix a running system.

Rob

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Robert Brockway B.Sc.
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