PHP-FPM Optimization

Out-of-box php fpm is configured for very low server specs such as a 2 core machine. It needs to be configured to match the hardware you are on. You need to factor on the most expensive processes you run. 

 Typically a low-end production server has 4 cores with 8 GB RAM so you can use the following configuration: 

 Edit the file /etc/apache2/mods-enabled/mpm-event.conf and add the following: 

 # event MPM

# StartServers: initial number of server processes to start

# MinSpareThreads: minimum number of worker threads which are kept spare

# MaxSpareThreads: maximum number of worker threads which are kept spare

# ThreadsPerChild: constant number of worker threads in each server process

# MaxRequestWorkers: maximum number of worker threads

# MaxConnectionsPerChild: maximum number of requests a server process serves

# <IfModule mpm_event_module>

# 	StartServers			 2

# 	MinSpareThreads		 25

# 	MaxSpareThreads		 75

# 	ThreadLimit			 64

# 	ThreadsPerChild		 25

# 	MaxRequestWorkers	 150

# 	MaxConnectionsPerChild 0

# </IfModule>

# ServerLimit (Total RAM - Memory used for Linux, DB, etc.) / process size

# StartServers (Number of Cores)

# MaxRequestWorkers (Total RAM - Memory used for Linux, DB, etc.) / process size

<IfModule mpm_event_module>

 # for c5 classes with only 8GB ram

 # ServerLimit 500

 StartServers 4

 MinSpareThreads 25

 MaxSpareThreads 75

 ThreadLimit 64

 ThreadsPerChild 25

 MaxRequestWorkers 2800

 # for c5 classes with only 8GB ram

 # MaxRequestWorkers 1400

 MaxConnectionsPerChild 1000

</IfModule> 

 Edit the file /etc/php/7.4/fpm/pool.d/www.conf and make sure the following setting are there: 

 ; settings explanation - don't need to copy this 

;pm.max_children (total RAM - (DB etc) / process size)

;pm.start_servers (cpu cores * 4)

;pm.min_spare_servers (cpu cores * 2)

;pm.max_spare_servers (cpu cores * 4)

; default is dynamic but that can churn up the memory because it leave processes lingering

; pm = dynamic

pm = ondemand

; default is pm.max_children = 5

pm.max_children = 256

; everything below is only relevant if using pm = dynamic

; for c class servers with only 8GB ram

; pm.max_children = 128

; default is pm.start_servers = 2

pm.start_servers = 16

; default is pm.min_spare_servers = 1

pm.min_spare_servers = 8

; default is pm.max_spare_servers = 3

pm.max_spare_servers = 16

; setting to 0 or leaving commented out will use the PHP_FCGI_MAX_REQUESTS value whatever that is.

pm.max_requests = 1000 

 Now we have allowed php to run a lot more threads we may run into a “too many open files” error. 

 To fix edit /etc/php/7.4/fpm/php-fpm.conf and change the rlimit_files to 4096. If you are still getting the “too many open files” error you can double this. 

 rlimit_files = 10000 

 You can also try editing /etc/security/limits.conf and adding the following: 

 * hard nofile 10000

* soft nofile 10000

www-data soft nofile 10000

www-data hard nofile 10000 

 Restart everything: 

 sudo service apache2 restart && sudo service php7.4-fpm restart 

 See also  https://medium.com/@sbuckpesch/apache2-and-php-fpm-performance-optimization-step-by-step-guide-1bfecf161534