Subject: Re: CVS commit: syssrc/sys/kern
To: Jaromir Dolecek <jdolecek@netbsd.org>
From: Perry E. Metzger <perry@piermont.com>
List: tech-kern
Date: 12/06/2002 14:37:37
Jaromir Dolecek <jdolecek@netbsd.org> writes:
> Perry E. Metzger wrote:
> > 
> > Jaromir Dolecek <jdolecek@netbsd.org> writes:
> > > It appeared there is no serious objection against the sleep.
> > 
> > If you think that our comments to the effect that we don't want it
> > constitute "no objection", then what WOULD be an objection?
> 
> Bill & you commented _after_ commit, so obviously I could not
> take it into account _before_ the commit.
> 
> Can you please explain your objection, other than "don't want it"?

I don't want my processes, especially non-blocking ones, to
mysteriously get involuntary stutters in their execution when they hit
an error condition. Roland mentioned, for example, what will happen to
a web server in a crisis if your idea is left in -- a bad situation
(cgi overload) goes worse (even static content is no longer delivered
in a timely manner and the number of open connections
soars). Similarly, see what would happen to several classes of SMTP
server during overload conditions -- merely being unable to
successfully trigger further processing of a message would turn into
getting untenable arbitrary delays in processing entirely, thus making
the situation WORSE by slowing down the time until exit of the daemon.

> The sleep thing is smart & simple solution to tough problem. I don't
> see how it could cause any new problem. So I currently don't see why
> to not have it there.

It has to go. Blocking processes arbitrary uncontrolable amounts of
time during error conditions is VERY VERY BAD.

-- 
Perry E. Metzger		perry@piermont.com