php-src/sapi/fastcgi

FastCGI module
--------------

This module requires the FastCGI development kit, available from
http://www.fastcgi.com/

Before building PHP, please enter the dev kit, and run:

./configure
make
make export

This will compile the library code required for the FastCGI module. All
that is then required is to configure PHP with the '--with-fastcgi' option.
After making the code, you will end up with a binary file called 'php'.
Installation of this file will depend on the web server being used, please
see their documentation for details.



Running the FastCGI PHP module
------------------------------

There are two ways to run the resulting 'php' binary after the fastcgi
version has been built:

1) Configure your web server to run the PHP binary itself.

This is the simplest method, obviously you will have to configure your
web server appropriately. Some web servers may also not support this method,
or may not be as efficient.

2) Run PHP separately from the web server.

In this setup, PHP is started as a separate process entirely from the web
server. It will listen on a socket for new FastCGI requests, and deliver
PHP pages as appropriate. This is the recommended way of running PHP-FastCGI.
To run this way, you must start the PHP binary running by giving it a port
number to listen to on the command line, e.g.:

./php 8002

(you can also specify a bind address, e.g. ./php localhost:8002. However, this
 relies on the FastCGI devkit and does not seem to work properly)

You must also configure your web server to connect to the appropriate port
in order to talk to the PHP FastCGI process.

The advantage of running PHP in this way is that it entirely separates the
web server and PHP process, so that one cannot disrupt the other. It also
allows PHP to be on an entirely separate machine from the web server if need
be, you could even have several web servers utilising the same running PHP
process if required!


Security
--------

Be sure to run the php binary as an appropriate userid. Also, firewall out
the port that PHP is listening on. In addition, you can set the environment
variable FCGI_WEB_SERVER_ADDRS to control who can connect to the FastCGI.
Set it to a comma separated list of IP addresses, e.g.:

export FCGI_WEB_SERVER_ADDRS=199.170.183.28,199.170.183.71


Tuning
------

There are a few tuning parameters that can be tweaked to control the
performance of FastCGI PHP. The following are environment variables that can
be set before running the PHP binary:

PHP_FCGI_CHILDREN  (default value: 8)

This controls how many child processes the PHP process spawns. When the
fastcgi starts, it creates a number of child processes which handle one
page request at a time. So by default, you will be able to handle 8
concurrent PHP page requests. Further requests will be queued.
Increasing this number will allow for better concurrency, especially if you
have pages that take a significant time to create, or supply a lot of data
(e.g. downloading huge files via PHP). On the other hand, having more
processes running will use more RAM, and letting too many PHP pages be
generated concurrently will mean that each request will be slow.

PHP_FCGI_MAX_REQUESTS (default value: 500)

This controls how many requests each child process will handle before
exitting. When one process exits, another will be created. This tuning is
necessary because several PHP functions are known to have memory leaks. If the
PHP processes were left around forever, they would be become very inefficient.