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From Ian Holsman <>
Subject Re: Currently known issues with 2.0.23
Date Wed, 08 Aug 2001 15:44:27 GMT
On 08 Aug 2001 08:29:13 -0700, Ryan Bloom wrote:
> > > > 2) Unix: The threaded MPM might take longer than expected to restart or
> > > >    shutdown on very-low-traffic (near idle) servers.  This is due to
> > > > the
> > >
> > > I dislike this.  It's the "near idle" that bothers me.  We rely on the
> > > OS to never starve a thread to get any restart or shutdown.  The
> > > server could easily be getting hit moderately, and not shutdown
> > > correctly.  I don't want to see us down-play the problem, and have
> > > people think that the server is working when it isn't.  There is a
> > > real chance that an admin can do a graceful restart, and still be
> > > serving requests off the old config for a very long time.
> >
> > How about "servers getting very few requests" instead of
> > "very-low-traffic (near idle) servers"?
> >
> > I threw the "near idle" bit in there to emphasize that (a) it effects
> > people running test servers that have nobody connecting to them at all,
> > and (b) that our definition here of "very low traffic" is not 100 conn/sec
> > as opposed to 1000 conn/sec, but more on the order of just a handful of
> > conn/sec, since 100 conn/sec might be seen as very low traffic by some
> > administrators.  ;-)
> a)  is just not true.  This doesn't affect only test servers, it affects anybody who
> isn't seeing a log of hits at a time.  And we haven't got a clue what the threshold
> is.  Again, we rely on the OS to make sure that every single thread gets
> the it's share of the connections.
> The real issue is that this MPM doesn't do what the admin expects.  Admins
> expect, that if you issue a graceful restart, then any requests that are in the
> middle of being served will be the last requests served with the current
> config.  The code doesn't do that.  Today's code continues to serve off of the
> current config until EVERY thread has had a chance to serve one request.  It
> doesn't matter if that takes 1 second or 1000 seconds.  We advertise graceful
> restart as doing one thing, and it does something else.
> > As for the shutdown issue... is it really an issue?  Generally speaking,
> > when I do an apachectl graceful, I can see the issue of which you speak,
> > but when I do an apachectl shutdown, it just goes.  Maybe I'm missing it.
> > <shrug>
> As far as the threaded child process is concerned, a graceful restart should
> be the exact same thing as a graceful shutdown.  If they aren't, then there is
> a bigger problem with this code than we know about.

how about a line like:
"gracefull restarts are currently not working properly on the threaded
MPM. The work-around at the moment is to do a full restart instead of a
graceful one."

That way admins have a workaround if they want to use threaded, and have
been warned as well.


> Ryan
> _____________________________________________________________________________
> Ryan Bloom               
> Covalent Technologies
> -----------------------------------------------------------------------------
Ian Holsman
Performance Measurement & Analysis
CNET Networks   -   (415) 364-8608

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