The site www.foxtons.co.uk Has front end apache servers serving images and static content which then proxy to a backend DB / CGI / Mod_perl machine.
Expect double your highest estimate of traffic (it was all running off one box previously, so I assumed not too much even though it was over loaded) and then double it and add some more. - We are getting loads more traffic than I though, there were no usable stats on the old server.
Set your Apache MaxClients to the highest you can, taking in to account the memory on the machine, it was embarising to realise that the site was slow, not because of the machine load or memory but because it was being hit harder than I thought and just couldn't open enough processes.
See lesson 2 and apply to back end mod_perl server.
The mod_perl guide on line http://perl.apache.org/ should be used in conjunctoin with the book "Writting Apache Modules with Perl and C". There were several thing in the online guide that I couldn't find in the book.
There is NO lesson 5
The main script was written for Apache::Registry, the load on the machine is between 2 and 5 so I definatly need to make it a propper mod_perl handle so it can share global variables such as a TT object. I hadn't realised until recently that this can not be done with Apache::Registry, though thinking about it it make sence.
I did find it interesting that when asking about, it turns out that most people, like my self, haven't ventured into mod_perl handles and tend to use Apache::Registry instead. I got my first mod_perl handle working today, was a lot easier than I thought it would be, still looking into some apache config options, there are just soo many.
PerlInitHandler, the mod_perl book says it can be put anywhere, but then it's quick reference card says it has to be in a Directory block in the conf. Only just remembered this lession.
Well, as usual enough rambeling...