Home

Awesome

Example configuration of php-fpm

Introduction

This is an example configuration php-fpm which is the preferred way of serving PHP with FastCGI. The old php-cgi is deprecated. You can even use a patch for PHP versions prior to 5.3.3, when fpm become an official PHP project.

Generalities

The way that php-fpm operates is through a master process that launches children processes (workers) that serve the requests. These workers can be run under a particular user. Making it appropriate for environments where there are several users each one running their own set of PHP apps.

php-fpm is pretty much a work in progress, although on one hand is IMHO the best thing to come out of PHP land in a lot of time, still lacks a lot of nice features like graceful restarts. Currently adding a new pool or reloading the config requires a full restart. Which causes some downtime. Work is in progress to provide graceful restarts/reloads like Nginx has.

It has the capacity to adjust the number of workers dynamically to the load, varying from a minimum to a specified maximum.

Load adequation

There's no algorithm for determining the number of children. It depends on your application.

A thread in the highload-php-en gives some tips on how to determine the number of children.

  1. If your load is CPU bound then the rule is that the number of children should be equal to number of CPUs plus 20 %.

    Example: Machine with 8 CPUs. Number of children = 10.

  2. If your load is I/O bound then apply the following rule:

    number_of_children = 1.2 * total_memory / average_space_per_process

    Example: PHP processes occupying 256 MB of average space in a machine with 2GB of RAM that can be used for running this PHP application.

    number_of_children = 1.2 * 2048 / 256

    giving: 10 children.

    Determine the medium space occupied by a PHP process and apply the above formula. The 1.2 factor is just a security factor, to use a much abused engineering term.

Features

  1. It uses a UNIX socket for connections from the web server to the FastCGI daemon.

  2. The php.ini is modified from the stock one that comes with the Debian package. The modifications were made by using a tiny script that I wrote for cleaning up a PHP config and that's available here on github.

  3. There's a single pool on this config that is run under the www-data user.

  4. Support for the status and ping functionalities of php-fpm. See here how to enable it for Nginx.

  5. Possbilitie of using three pools simultaneously to provide load balancing on the FCGI upstream.

Installation

  1. Clone the git repo: git://github.com/perusio/php-fpm-example-config.

  2. Alter the php-fpm.conf and the pool.d/www.conf file to your liking. Add any pool that you might want.

  3. Copy the files to the destination directory:

    cp php5-fpm.conf /etc/php5/fpm

    cp -a pool.d /etc/php5/fpm

  4. (Re)start php5-fpm with service php5-fpm restart or service php5-fpm start if starting php-fpm anew.

Caveats

Remember to always do service php5-fpm restart after adding a new pool or modifying the configuration of an existing one.