I have Debian 6,Apache 2.2.16. On this run two page first.net - many visit user, second.net - much less page visit. When restart apache2,that run both page ok, but after few minutes/hours cant load page second.net. In /log/apache2/second.net/error is: mod_fcgid: can't apply process slot for /var/www/webuser/php5-wrap In log /log/apache2/first.net is it certainly but less(given the number of user). When is error? What is wrong?
Check how many processes Apache has running. It may be that some scripts are not shutting down after the connection has dropped, or the connections are not being dropped from the client(s), resulting in an exhaustion of resources. I think you can set a connection time-out so that connections are automatically dropped after some period of inactivity. You should also be able to increase the number of allowed connections in the Apache configuration files. I'm just getting started in a new job where this is information I need to learn, but I am not there yet, so this is as far as I can take you.