I have had this config running on ubuntu 11.10 for more than one year. I had to move the service to a larger server, so I made a complete copy of the os disk with clonezilla and restored it to the new server. I upgraded the OS on the new server to 12.04. All other things are identical on both systems.
My problem is this: Apache runs fine and is far from the maxclients limit. Suddenly, php5-cgi spawns more and more processes , they are all in state "working" , and apache can not server requests anymore. All apache requests turn into "W" state, and sit there, while new requests are coming, and eventually all requests build up to the maxclients setting. 1 minute later all fcgi processes suddenly turn their state to "ready" and all is back to normal.
During the time this happens, Apache does not server the website. It looks like fcgi simply hangs and stops responding. "top" shows nothing at all, everything looks fine, no processes in D state or anything. Apache error log says that fcgid can't apply process slot, when this happens. But I dont understand why suddenly this started. My only thought would be that something is broken during the upgrade from 11.10 to 12.04. But why is it doing it so randomly, regardless of usage, load, or anything else?
Will very much appreciate any help!
Having said all that, I want to ask if anyone is aware why did the config break?