While mpm prefork is not the fastest mpm available for Apache2 web servers and also does not support HTTP/2 and ALPN, it is thread-safe and not closest to slower when the number of traffic is lower and CDN is extensively used. PHP FPM is faster but demands a somewhat expert person to optimize. That is the reason why some people still prefer mod_php and mpm prefork.
The above paragraphs explain why we are discussing optimizing php.ini for WordPress when mod_php and mpm prefork are used. Like all the Apache2 modules, mod_php directives provide functionality specific for php parsing, and some others can be set in php.ini settings. There is a WordPress plugin named “Health Check & Troubleshooting” (it is by WordPress core developers) which can help you.
This a safe yet effective configuration for mpm prefork:
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1 2 3 4 5 | StartServers 5 MinSpareServers 5 MaxSpareServers 10 MaxRequestWorkers 150 MaxConnectionsPerChild 0 |
- StartServers is the number of child processes created upon starting Apache.
- MaxRequestWorkers is the maximum number of connections that can be open at one time. After reaching this limit, the next incoming connections will be queued.
- MinSpareServers and MaxSpareServers refer to the number of child processes that should be idle at any one time.
- MaxConnectionsPerChild determines the total number of connections each child process can serve before it is restarted. This safeguards against memory leaks when using mod_php.
You can set MaxConnectionsPerChild to a high value (e.g. 1,000) rather than leaving it to 0 (= unlimited). You have to set the allowed PHP limit for your WordPress installation from the wp-config.php file:
1 | define('WP_MEMORY_LIMIT', '512M'); |
512MB is more than enough for each PHP process. Most of the managed WordPress hosting keeps it around 256MB. On php.ini files, you need to the settings to these example values:
1 2 3 4 5 6 7 | upload_max_filesize = 32M post_max_size = 48M memory_limit = 1024M max_execution_time = 600 max_input_vars = 1000 max_input_time = 400 # max_input_time=-1 |
Which php.ini file to modify? Run locate command to find the locations:
1 | locate php.ini |
Usually, the loaded configuration file is in the CLI directory, but you should also modify the php.ini file which is under Apache’s directory. The CGI one is not related to the present settings.
