[Sunhelp] at job problems

[steve price]

at , while running in its own shell, still competes
with other processes for system resources.

therefore its time accuracy is never exact.  several
minutes or longer depending on the number of jobs,
available memory etc are the norm.

the man page (solaris) for at states:

Regardless of queue used, cron has a limit of 100 
jobs in execution at any time.

There can be delays in cron at job execution. In some
cases, these delays can compound to the point that
cron job processing appears to be hung. All jobs will
be executed eventually.  When the delays are
excessive, the only workaround is to kill and restart
cron.

My linux man page goes further and says:

At and batch as presently implemented are not suitable
when users are competing for resources.  If this is
the case at your site, you might want to consider
another batch system, such as nqs.

//regards

--- Mark Sailer <msailer at instinet.com> wrote:
> Looking for some assistance in explaining how "at"
> runs.
> This is running on a E6502, 20 cpus, 20g RAM,
> SOLARIS 7
> 
> Our developers have a script that calls some
> exectuables based on
> certain parameters.  The call in the script is "at
> now".
> By time the script ends, the time for the at jobs is
> already in the
> past.
> It can take a few minutes or more before the at jobs
> run.
> I have already modified /etc/cron.d/queuedefs to
> read
> a.30j10n
> b.2j2n90w 
> restarted cron and have rebooted the server.
> 
> After I run the users script (some long list of
> stuff |at now)
> and this is what I get:
> 
> lassie:/u/rts 3> date
> Mon Jul 31 18:51:44 EDT 2000
> lassie:/u/rts 4> at -l
> 965083827.a     Mon Jul 31 18:50:27 2000
> 965083828.a     Mon Jul 31 18:50:28 2000
> 965083829.a     Mon Jul 31 18:50:29 2000
> 965083830.a     Mon Jul 31 18:50:30 2000
> 965083831.a     Mon Jul 31 18:50:31 2000
> 965083832.a     Mon Jul 31 18:50:32 2000
> lassie:/u/rts 5>        
> 
> As you can see, only 6 jobs (much less than the 30
> jobs queued).    
> 
> I have tried running at jobs by hand (at now) and
> have seen where it can
> take over 30 seconds, even minutes for the job to be
> processed from the
> queue and it is the only queued job.  The job is a
> simple "ls".
> 
> What's going on with cron and at jobs?
> I'm getting beat up over this and I can't explain
> what is happening?
> 
> Thanks
> Mark
> _______________________________________________
> SunHELP maillist  -  SunHELP at sunhelp.org
> http://www.sunhelp.org/mailman/listinfo/sunhelp


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