PHP-FPM Process Calculator

PHP-FPM (FastCGI Process Manager) is an alternative PHP FastCGI implementation with some additional features useful for sites of any size, especially busier sites.

Proper process calculation ensures optimal use of server resources, improves performance, and prevents issues like memory exhaustion.

These settings can be applied in your php-fpm.conf file or the pool configuration file, typically located in /etc/php/8.x/fpm/pool.d/www.conf (path may vary based on your setup).

Consider using the dynamic pm mode, which allows PHP-FPM to adjust the number of child processes based on the current load.

While these calculations provide an excellent starting point, it's important to test and adjust based on your specific environment and application needs.

pm.max_children sets the maximum number of child processes that can be created to serve requests. It's crucial for controlling server resource usage.

These settings work together to manage the number of idle processes. pm.start_servers sets the number of child processes created on startup, while pm.min_spare_servers and pm.max_spare_servers define the minimum and maximum number of idle child processes.

The RAM buffer is a safety margin to prevent your server from using all available RAM. It helps ensure system stability and provides room for other OS/processes.

It's recommended to review your PHP-FPM settings regularly, especially after significant changes in traffic patterns or server resources. Monthly or quarterly reviews are common practices.

While this calculator is specifically designed for PHP-FPM, the general principles of resource allocation can be applied to other server configurations. However, the specific settings and terminologies may differ.

PHP-FPM offers better performance and more granular control over process management compared to traditional PHP CGI. It allows for better resource utilization and can handle high-traffic situations more efficiently.

Dynamic mode adjusts the number of PHP-FPM processes based on demand, which is good for variable traffic. Static mode maintains a fixed number of processes at all times, providing better performance for high-traffic sites at the cost of higher resource usage.

The realpath cache stores the real file paths of files that PHP opens, avoiding the need for repeated file system lookups. Properly sizing this cache significantly improves performance, especially for applications with many included files like WordPress or frameworks.

OPcache improves PHP performance by storing precompiled script bytecode in memory, eliminating the need for PHP to load and parse scripts on each request. This can result in a 30-70% performance improvement depending on your application.

The pm.max_requests setting defines the number of requests each child process should execute before respawning. This helps mitigate memory leaks in PHP applications by periodically refreshing processes, preventing them from growing too large over time.

Yes, it's good practice to set the memory_limit to match your estimated process size. This ensures PHP processes don't use more memory than you've planned for in your calculations, preventing potential server instability.