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.

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.

I've seen a formula being passed around that supposedly is the right thing.

The formula is:

number_of_children = (total_memory - 512 MB) / 128 MB

it's implied that each child consumes up to 128 MB.

Using this formula we get numbers significantly below the defaults that come with the distribution packages like the one provided by Debian and that is included here for completeness and providing a term of comparison. It's named php5-fpm.conf.dpkg-dist.

This is the configuration I use for local development you should adjust it to your setup and conditions if usage.

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.

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.

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