[ic] mod_interchange and Apache MaxClients

John1 list_subscriber at yahoo.co.uk
Wed Nov 16 20:25:31 EST 2005

On Wednesday, November 16, 2005 6:09 PM, rphipps at reliant-solutions.com 

>> From: interchange-users-bounces at icdevgroup.org
>> [mailto:interchange-users- 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
>>> MaxClients 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 restart 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
>> service 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
>> interruption and correct the underlying issue.  That's a task that
>> can only really be performed on a system that exhibits the problem,
>> of course, and it'd be difficult to estimate the time it might take
>> investigate and correct the 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.
I will try to do this but may take me a while to remember/figure out how to 
do this - if you have time to post a snippet from you catalog config once 
you have done this it would be appreciated.

> 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 follows:
> <Location />
>        SetHandler interchange-handler
>        InterchangeServer
>        DropRequestList /default.ida /x.ida /cmd.exe /root.exe
>        OrdinaryFileList /w3c/ /webstats/ /rss/ /classes/ /banner/
> /images/ /guides/ /nav/ /ebay/ /guides/
> </Location>
I am running via Unix sockets:
<Location />
InterchangeServer /usr/local/interchange/socket

I have recently also enabled Inet mode from localhost by adding the 
following to my interchange.cfg:

Inet_Mode Yes
TcpMap -

The reason I did this was to allow me to telnet to Interchange when the site 
stopped responding to try to verify whether Interchange was still 
responding.  When the site last stopped I did "telnet 7786" and I 
did get a connection, but I wasn't sure what else to input in the telnet 
session confirm whether Interchange was responding.  Is this a useful test 
and if so, what should I key into the telnet session to confirm Interchange 
is alive and well?  Thanks

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