PHP-FPM

What is PHP-FPM?

PHP-FPM (FastCGI Process Manager) is an alternative PHP FastCGI implementation with features useful for high-load websites.

Installation

# Ubuntu/Debian
sudo apt install php-fpm

# Check version
php-fpm -v

# Check status
sudo systemctl status php8.2-fpm

Nginx + PHP-FPM

server {
    listen 80;
    server_name example.com;
    root /var/www/html;
    index index.php index.html;

    location / {
        try_files $uri $uri/ /index.php?$query_string;
    }

    location ~ \.php$ {
        fastcgi_pass unix:/var/run/php/php8.2-fpm.sock;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        include fastcgi_params;
    }
}

Pool Configuration

/etc/php/8.2/fpm/pool.d/www.conf:

[www]
user = www-data
group = www-data
listen = /var/run/php/php8.2-fpm.sock

; Process management
pm = dynamic
pm.max_children = 50
pm.start_servers = 5
pm.min_spare_servers = 5
pm.max_spare_servers = 35

; Logging
access.log = /var/log/php-fpm/access.log
slowlog = /var/log/php-fpm/slow.log
request_slowlog_timeout = 5s

Process Modes

Mode	Description	Best For
static	Fixed number of children	Predictable load
dynamic	Scales based on demand	Most cases
ondemand	Spawns on request	Low traffic

Management

sudo systemctl start php8.2-fpm
sudo systemctl stop php8.2-fpm
sudo systemctl restart php8.2-fpm
sudo systemctl reload php8.2-fpm  # Graceful reload

vs Python/Node

Aspect	PHP-FPM	Python	Node.js
Model	Process pool	Single process	Event loop
Memory	Per-request	Persistent	Persistent
Scaling	FPM handles	Supervisor/PM2	PM2 cluster
Best For	Web pages	APIs, scripts	Real-time