Many php-fpm: pool www processes running but Apache isn't

Question

I'm using CentOS 6.4 (x86) VPS with Nginx.

In Webmin Running processes table I found up to 8 "php-fpm: pool www" running processes that "Apache" is the owner, but Apache isn't running!

This consumes a lot of RAM memory. It is necessary for the nginx jobs or not? Sorry for this (stupid?) question but I'm newbie about Server management.

Thank you in advance.

Answer 1

The processing running will be needed and won't be being wasted.

One of the first things that should be defined in your PHP-FPM config file is what user and group PHP-FPM should be running under.

Presumably your config file says to run PHP-FPM under the user 'Apache'. You can change this to whatever you like, so long as you get the file permission right for PHP-FPM to access your php files.

However if PHP-FPM is taking up a lot of memory then you should tweak the values for the number of pools and how much memory each one can use. In particular you could reduce the settings:

pm.start_servers = 4
pm.min_spare_servers = 2

To not have as many PHP-FPM processes sitting around idle when there is no load.

Answer 2

PHP-FPM has it's own separate process manager and really isn't connected to anything other than itself. Other software will connect to it, IE: nginx / apache. You probably see the "Apache" user running the process because of the pool configuration you have. You can easily change the configuration and then restart the FPM Process.

If you do not wish to have stale processes running while they are not used, then I would recommend that you change the PM option in the pool configuration from Static/Dynamic to ondemand. This way, FPM will only spool up when it is needed.

Many people use the Static/Dynamic options when they need specific variations for the processes they are running, IE: a site that receives a lot of constant traffic.

Depending on your FPM installation you'll normally find the configurations in /etc/php. I keep my configurations in /usr/local/etc/php-fpm/ or /usr/local/etc/fpm.d/