Apache Throttling Itself?

[Charles Jones]

fouldragon at aol.com wrote:
> I've just set up a new (virtual-bla-bla-bla) server for a site I'm 
> working on.
>
> The test server was FC6, with Plesk 8.3 and a recent PHP and MySQL 
> hacked on.
>
> The new one is CentOS5, with CPanel 11, and a comparably recent PHP and 
> MySQL included with the install.
>
> The site generally fell into place once I fixed some incorrect 
> absolute/hard coded stuff, except for one thing:
>
> One of the scripts on the site is expected to get POUNDED (it provides 
> an interface to a database, which is potentially digested by sites 
> hosted on the same server and different servers)
>
> On the test setup, it worked fine.
>
> On the new set up, if you hit the script too frequently -- 5 or 6 times 
> per second or so, the server responds "403 forbidden".  If you lay off 
> for a couple seconds, it works fine again.
>
> Since the script can be hit several times in the "back end" of 
> generating a page, that's unacceptable.
>
>
> The signature of the server is Apache/2.2.8 (Unix) mod_ssl/2.2.8 
> OpenSSL/0.9.8e-fips-rhel5 DAV/2 mod_auth_passthrough/2.1 
> mod_bwlimited/1.4 FrontPage/5.0.2.2635 PHP/5.2.6 Server at (snip) Port 
> 80
>
>
>
> I suspect it's some Apache setting knocking the users off, since Apache 
> claims responsibility for the 403, but can anyone give me a good place 
> to start looking?  I don't want to just dump the httpd.conf from the 
> other server (which is a LITTLE different configuration-wise) on here 
> and hope.
Is the script in question a php script?  Check the error log 
(/var/log/httpd/error_log). I suspect you are hitting the limit of 
database connections, which would make the script error out.  That, or 
hitting a php memory or execution limit, all of which can be fixed by 
tweaking the php.ini or my.cnf.