I have fastCGI with PHP
However, server runs fine for several hours and then suddenly I have php error log full of:
mod_fcgid: can't apply process slot for /var/www/php-bin/website/php
At the same time, there is no spike in activity on the web, CPUs are not spiking, all seems normal based on the server usage.
If I restart apache, all is running ok again for several hours and then situation repeats.
I have tried to set higher values to fcgid settings:
FcgidMaxProcesses 18000
FcgidMaxProcessesPerClass 3800
but the problem stil persist.
What is interesting, I also have the second server with totally different setup and SW versions (FastCGI as PHP module), but the same problem sometimes (not so frequently) occurs there as well.
So I am wondering, can this problem be caused by some PHP script? On both servers, there are some PHP libraries that are the same.
In generall, how to track down what is causing this? On debug server, this problem is non-existing and on production, I cannot blindly change settings and reset server over and over again.