Reduce PHP-FPM memory usage on VestaCP

VestaCP comes prepacked with PHP-FPM (if you select the option when installing) which manages PHP processes. By default it spawns processes that stay alive constantly eating memory. We can further optimise the PHP-FPM settings by tweaking the configuration that’s made when adding a new domain name in an attempt to reduce PHP-FPM memory usage.

VestaCP default PHP-FPM settings

The file /usr/local/vesta/data/templates/web/php-fpm/default.tpl looks by default like this:

[%backend%]
listen = 127.0.0.1:%backend_port%
listen.allowed_clients = 127.0.0.1

user = %user%
group = %user%

pm = dynamic
pm.max_children = 50
pm.start_servers = 3
pm.min_spare_servers = 2
pm.max_spare_servers = 10

env[HOSTNAME] = $HOSTNAME
env[PATH] = /usr/local/bin:/usr/bin:/bin
env[TMP] = /tmp
env[TMPDIR] = /tmp
env[TEMP] = /tmp

And the socket file /usr/local/vesta/data/templates/web/php-fpm/socket.tpl looks like this:

[%backend%]
listen = /var/run/php5-%backend%.sock
listen.allowed_clients = 127.0.0.1

user = %user%
group = %user%

listen.owner = %user%
listen.group = nginx

pm = dynamic
pm.max_children = 50
pm.start_servers = 3
pm.min_spare_servers = 2
pm.max_spare_servers = 10

env[HOSTNAME] = $HOSTNAME
env[PATH] = /usr/local/bin:/usr/bin:/bin
env[TMP] = /tmp
env[TMPDIR] = /tmp
env[TEMP] = /tmp

Reduce PHP-FPM memory usage

Change the file /usr/local/vesta/data/templates/web/php-fpm/default.tpl to this:

[%backend%]
listen = 127.0.0.1:%backend_port%
listen.allowed_clients = 127.0.0.1

user = %user%
group = %user%

pm = ondemand
pm.max_children = 50
pm.start_servers = 3
pm.min_spare_servers = 2
pm.max_spare_servers = 10
pm.process_idle_timeout = 10s
pm.max_requests = 500

env[HOSTNAME] = $HOSTNAME
env[PATH] = /usr/local/bin:/usr/bin:/bin
env[TMP] = /tmp
env[TMPDIR] = /tmp
env[TEMP] = /tmp

Now change the file /usr/local/vesta/data/templates/web/php-fpm/socket.tpl to this:

[%backend%]
listen = /var/run/php5-%backend%.sock
listen.allowed_clients = 127.0.0.1

user = %user%
group = %user%

listen.owner = %user%
listen.group = nginx

pm = ondemand
pm.max_children = 50
pm.start_servers = 3
pm.min_spare_servers = 2
pm.max_spare_servers = 10
pm.process_idle_timeout = 10s
pm.max_requests = 500

env[HOSTNAME] = $HOSTNAME
env[PATH] = /usr/local/bin:/usr/bin:/bin
env[TMP] = /tmp
env[TMPDIR] = /tmp
env[TEMP] = /tmp

Essentially, what this does is make PHP-FPM spawn PHP processes when needed, and let others die. By changing pm = dynamic to pm = ondemand we can use PHP-FPM’s feature to reduce PHP-FPM memory usage.

I have also added in pm.process_idle_timeout = 10s which will kill the PHP process after 10 seconds of inactivity, in an attempt to reduce PHP-FPM memory usage, and set pm.max_requests = 500. The pm.max_requests setting is advised as covered here (basically helping to stop memory leaks).

Rebuild all the PHP-FPM configuration files

After changing these files the settings will become active for any new website added. Unfortunately, at this time it’s not possible to use any of VestaCP’s “rebuild” functions to re-create the PHP-FPM configuration settings for each domain name. You have to edit each file individually by adding/changing the new settings:

pm = ondemand
pm.process_idle_timeout = 10s
pm.max_requests = 500

The location of every PHP-FPM configuration file is here: /etc/php-fpm.d

Restart PHP-FPM

For whatever reason sometimes I find that the linux command doesn’t restart the PHP-FPM processes, so I simply log into Vesta and click the Server link and hit restart on PHP-FPM and NGINX.

All done! Now you have reduced PHP-FPM’s memory usage!