PHP-FPM for WordPress gobbling up memory
PHP-FPM is the culprit.
I started looking for an update and found that my version (5.3.3) was the last independent version of PHP-FPM. Subsequently it was merged into the main PHP project.
PHP is already on 5.5.0 so I decided to upgrade to that. However, ISPConfig3 is not compatible with 5.5.0 so I ended up upgrading to 5.4.16 instead.
I also set pm = ondemand (though pm = dynamic could have worked equally well).
Now, my memory usage is 450MB, down from some 3.5GB!
Umm may bad config, PHP-fpm never kill child ( so never restar, never clean RAM ), APC caching, php-fpm use 128 MB of RAM each process is they dont restart can use a lot of RAM.
Maybe you can post some logs and configuration.
You use w3tc on wordpress or some plugin than caching and save info on APC ?