News Group Posts

runaway processes using cpu time secstopio

From: Bela Lubkin <belal@sco.com>
Subject: Re: Defunct processes hogging CPU?
Date: Tue, 26 Feb 2002 03:45:14 GMT
References: <u7kru9af1iosb0@corp.supernews.com>
<3c7af943$0$79553$8eec23a@newsreader.tycho.net> 

John DuBois wrote:

> In article <u7kru9af1iosb0@corp.supernews.com>,
> Scott <news@sccsx-ltd.co.uk> wrote:
> >I've noticed on our OSR5.0.5 system, that defunct processes (or processes
> >that have been grabbed by init, where users have not logged off properly),
> >seem to be hogging the CPU.
> >These processes always have a very high C value on the PS listing, are
> >always at the top of top, and send the load average on w sky high.
> >Also, if there's two or three of these, sar reports idle time or 0%, it's
> >normally rarely below 85!
> >As soon as I've killed them off, everything returns to normal.
> >
> >Why should SCO bother with these redundant processes?
> 
> These are not defunct processes.  Defunct processes (zombies) are dead by
> definition, and cannot consume CPU time.  The usual cause of the problem you
> are seeing is an application that ignores failure indication when reading from
> the tty and so after the tty is closed goes into a read loop consuming as much
> CPU time as it can.  You can try setting SECSTOPIO to 1 (5.0.4 and later
> only!), so that the process will get an extra signal when it tries this.  If
> that doesn't work, you can try setting a CPU time limit to minimize the CPU
> thrashing that misbehaving processes cause (invoke the application through a
> ksh script that first does 'ulimit -t nnn').

There was actually a problem along these lines that was _caused_ by
SECSTOPIO being 1.  So whatever its current value is, you might changing
it to the other.  The variable exists in all releases of SCO Unix
starting with 3.2v2.0, I believe.

>Bela<
 

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