[ic] mod_interchange and Apache MaxClients

John1 list_subscriber at yahoo.co.uk
Mon Nov 14 18:52:14 EST 2005

I am running Apache with mod_interchange 1.32, with the following httpd.conf 

StartServers  5
MinSpareServers  5
MaxSpareServers  10
MaxClients  150
MaxRequestsPerChild 10000

I am finding that even with these settings Apache is hitting its MaxClients 
limit now and again as evidenced by the following entry in the Apache error 

"server reached MaxClients setting, consider raising the MaxClients setting"

The problem is that once Apache bumps up against this limit, the site hangs, 

i.e.  The Apache processes running stay at 150 indefinitely and so the site 
becomes permanently inaccessible.

I had thought that once MaxClients was reached TCP requests would be queued 
and so eventually the lockout situation would end once the backlog of 
requests was cleared.

Having come across an old post to the mailing list:

...I am wondering whether the reason that the lockout never clears may be to 
do with how mod_interchange queues requests for Apache?  Does anyone know 
whether this could be the case, or if not, can anyone else suggest why I am 
getting *permanent* lockout once the MaxClient limit is bumped up against. 
i.e. currently I am forced to restart Apache once the MaxClient limit is 

I have a second related question:

The reason that the MaxClient is being bumped from time to time is often 
(though not always) due to http floods from scripts looking for files on my 
server that don't exist (i.e. looking for files with known security holes). 
Does anyone have any suggestions on how best to stop these sort of floods 
bringing down my server?

Any suggestions on how to solve this issue (and the lockout problem) would 
be greatly appreciated as I am currently having to restart Apache several 
times a day.  Thanks. 

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