I have installed virtualmin on my server. The httpd server is the default httpd-2.2.3.vm.
I want to recompile the apache, what should I do?
step by step please, thanks.
It looks like these two posts are related:
https://www.virtualmin.com/node/17156
It really could take hours to write step by step instructions on how to properly compile Apache on your server, and probably longer to perform those instructions 
Further, anytime an Apache security update came out, you’d have to recompile Apache. Manually compiling anything for your server can be a real maintenance problem, and I highly recommend against it.
My recommendation is to find a different solution to your problem – it sounded like you’re seeing some FCGID errors. There’s multiple things that can cause those errors, but a quick and simple fix would be to change your site to use CGI rather than FCGID.
You can do that by going into Server Configuration -> Website Options, and change the PHP Execution mode to CGI.
-Eric
It sounds like something strange is going on
What output do you receive if you go into System Configuration -> Re-Check Config?
That should check various setting to make sure everything looks okay.
-Eric