Too many MailScanners Spawned

[Julian Field]

At 05:44 26/10/2002, you wrote:
>On Fri, 2002-10-25 at 23:15, Matthew Davis wrote:
> > Using MailScanner-4.02-3 RPM install, and default .conf sets
> >
> > Max Children = 5
> >
> > <rant>
> > Which might be good for some, but for my slow 300 mhz + 32 meg RAM mail
> server, having 5 MailScanners running means I could have 5 spamd's running.

Rubbish :-) MailScanner doesn't use spamd at all, never has done and never
will do.

>Which the load of 1 is plenty of load.  Anyway, a batch of mabye 20 or so
>emails came in and it took maybe 30 minutes to process them.

So reduce the "Max Children" setting. But as a large proportion of the time
MailScanner is actually sitting around waiting for DNS replies, you are
probably still better off with 2 or 3 children.

> > </rant>
> >
> > Enough of rambling, I tried to set Max Children = 1, but it still loads
> 2 copies of MailScanner.

1 of which is the small parent process, whose sole job is to fork off child
processes. While the children are running, it does absolutely nothing, it
just sits there quietly waiting. So it uses no CPU, and any memory it uses
in your system will very quickly get swapped out to disk in favour of the
children that are doing the work.

>The nicest thing that you could do for this box would be to give it more
>memory. If you could get the installed memory into the 96Mb+ range
>(assuming that you aren't running X routinely) you'd see an improvement
>if the performance of the system. Given that mail scanning involves a
>fair bit of disk I/O, you could then profitably run 2-4 children. The
>scanners will tend to interleave in their use of I/O and disk, resulting
>in faster overall message processing.

Considering the price of memory at the moment, I would second that and
strongly advise you chuck a bit more RAM at it. You may find your server is
doing a lot of swapping, but you should be able to work out exactly what is
causing the poor performance using all the usual system admin and analysis
tools at your disposal. I'm not going to try to teach you how to use them :-)
--
Julian Field                Teaching Systems Manager
jkf at ecs.soton.ac.uk         Dept. of Electronics & Computer Science
Tel. 023 8059 2817          University of Southampton
                             Southampton SO17 1BJ