[ic] mod_interchange and Apache MaxClients

Ron Phipps rphipps at reliant-solutions.com
Wed Nov 16 13:09:52 EST 2005

> From: interchange-users-bounces at icdevgroup.org
> bounces at icdevgroup.org] On Behalf Of Kevin Walsh
> Sent: Wednesday, November 16, 2005 9:12 AM
> John1 [list_subscriber at yahoo.co.uk] wrote:
> > I believe that my site only actually ceases to respond once
> is
> > reached.  Even though MaxClients is no doubt not the underlying
cause of
> the
> > problem (but a symptom) what I would like to do is automatically
> > apache and interchange when MaxClients is reached as this would keep
> website
> > downtime to a minimum.
> >
> You'll probably find that it's the other way around.  A pause in
> will cause further requests to be queued until the MaxClients limit is
> reached.  If you wait for the MaxClients warning before restarting
> Interchange then you will probably loose a lot of user sessions in the
> interim.

I have determined in my case that it is not a MaxClients issue and that
just masks the problem.  My site still went down when MaxClients was at
1024.  I did not get the MaxClients reached error at that time, so I
believe that MaxClients is only reached after the site is down for a
certain amount of time, most likely the amount of time it takes to queue
up that many clients.

> I think it would be better to find the cause of the service
> and correct the underlying issue.  That's a task that can only really
> performed on a system that exhibits the problem, of course, and it'd
> difficult to estimate the time it might take investigate and correct
> issue.

I will continue to look into this issue and will only be running my
restart script when I'm away from the computer, to keep the site live.
However when I'm at the computer I will be waiting for the site to go
down so I can try to figure out what is causing the problem.

Kevin asked me to try the following:

You could set up a cgi-bin executable on a "testing" subdomain, along
with a "/cgi-bin/foo" alias on the end of your Catalog line.  if/when
Interchange stops responding, try sending requests through the CGI. If
the requests fail there as well then the finger points at Interchange,
otherwise it would look more like a mod_interchange (or Apache module
API) issue.

I will be trying the above steps the next time the site goes down to see
if we are seeing a problem with Interchange or a problem with
Apache/mod_interchange communicating with Interchange.  John and Jeff
it'd be great if you could do the same on your systems so we have more
then one result.

Also post your mod_interchange section for Apache so we can see if we
are all communicating with IC via unix sockets or tcp.  My config is as

<Location />
        SetHandler interchange-handler
        DropRequestList /default.ida /x.ida /cmd.exe /root.exe
        OrdinaryFileList /w3c/ /webstats/ /rss/ /classes/ /banner/
/images/ /guides/ /nav/ /ebay/ /guides/


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