It seems that keeping up the the apache mpm_prefork and mod_php will not be the solution anymore. Most sites suggested to use mpm_worker instead, because it uses less memory (and my problem was, that my Apache consumed all my memory). On the other hand there could be some problems with thread-safety, but I liked to give it a try. PHP will not me used as an Apache module any more. Instead we will run PHP as a FastCGI script.

A short step by step tutorial for switching from mpm_prefork to mpm_worker with using PHP.

• Open a terminal session as a root user.

  apt-get install apache2-mpm-worker libapache2-mod-fcgid php5-cgi

  apt will complain about a few things and will remove some of the previous installed packages. After installation make sure that mod_fcgid is enabled.

• Edit you /etc/apache2/apache2.conf or /etc/apache2/httpd.conf or any config file that will be parsed by apache and add this:
  1. AddHandler fcgid-script .php
  2. FCGIWrapper /usr/lib/cgi-bin/php5 .php
  3. Options ExecCGI FollowSymlinks Indexes
• Now enter you /etc/apache2/sites-available directory and edit all the the files there. Every file should contain at least one “VirtualHost” node. Within these “VirtualHost” nodes there should be one or two “Directory” nodes. If not already there add a new line starting with “Options” and add “Indexes” and “ExecCGI” as parameters on these lines. It should be look like this one:
  1. Options Indexes FollowSymLinks MultiViews ExecCGI
  2. AllowOverride AuthConfig
  3. Order allow,deny
  4. allow from all
• Restart apache:

  /etc/init.d/apache2 restart

Hopefully now everything should work as before. If you had enabled eAccelerator or any other byte code cache system or if you had mode some modifications on you php.ini you now have to copy them to your “new” php.ini located at /etc/php5/cgi/php.ini

A few things wont work as before, e.g. when use user authentication by PHP and not by htaccess. There are also a few issues I read about, but nothing which affect my sites.

As a result I would say spending this hours messing around with Apache and mod_fcgid was a good investment. My server now need only 90 MB Ram when idle, it was 250 MB Ram before. Even under load memory consumption stays lower as before. I hope this will be the last tweak for I longer time.

Using PHP as a FastCGI script gives you a lot of new options. So if you have a lot of time to spent or very worried about the security of you web server you could use the Apache module suexec which then could execute the script as a special user and not as the default web server user www-data. It could even use multiple user for each virtual host / directory.

Interesting links:

• http://brian.moonspot.net/2008/02/13/apache-worker-and-php/
• http://www.ibm.com/developerworks/linux/library/l-tune-lamp-2.html Tuning Apache and PHP
• http://www.ibm.com/developerworks/library/l-tune-lamp-3.html Tuning MySQL
• http://ivan.gudangbaca.com/installing_apache2_and_php5_using_mod_fcgid More detailed instruction how to install mpm_worker and PHP via mod_fcgid

PHP is not the fastest scripting language, that truly a fact. Except from optimizing the scripts there a few possibilities to speed everything up. One is to install a byte code optimizer and cache on your server. They cache the byte code created by the PHP parser and try to optimise it. So every time some one requests for a page on your server the script does not have to be parsed again. This brings a speedup of 120 – 250% depending on you script. There are several byte code caching program available, the one I like most is eAccelerator. Sadly eAccelerator is not available through the Ubuntu repositories so you have install them yourself. Here is a short description how to archive this!
Everything is done from the terminal as a root user.

• Prepare you system for compiling a PHP extension:

  apt-get install build-essential php5-dev

• Choosing a folder for build process. I used “/usr/local/src/”
• Getting the sources from the eAccelerator site:

  wget http://bart.eaccelerator.net/source/0.9.5.3/eaccelerator-0.9.5.3.zip

• Extract and delete the archive

  unzip eaccelerator-0.9.5.3.zip && rm eaccelerator-0.9.5.3.zip

• Enter the folder

  cd eaccelerator-0.9.5.3

• Prepare as a new PHP extension and compilation

  phpize
  ./configure --enable-eaccelerator=shared

• Compile and install

  make
  make install

  The install process prints out a folder where eAccelerator has been installed. Remember or copy it, you will need this later.

• Enabling eAcceletor: Editing your “php.ini” or create a new ini file in you conf.d directory of PHP. (You can find them here: “/etc/php5/”.) Insert the following:

  zend_extension                  = "/usr/lib/php5/20060613+lfs/eaccelerator.so"
  eaccelerator.shm_size           = "0"
  eaccelerator.cache_dir          = "/var/cache/eaccelerator"
  eaccelerator.enable             = "1"
  eaccelerator.optimizer          = "1"
  eaccelerator.check_mtime        = "1"
  eaccelerator.debug              = "0"
  eaccelerator.filter             = ""
  eaccelerator.shm_max            = "0"
  eaccelerator.shm_ttl            = "0"
  eaccelerator.shm_prune_period   = "0"
  eaccelerator.shm_only           = "0"
  eaccelerator.compress           = "1"
  eaccelerator.compress_level     = "7"
  eaccelerator.allowed_admin_path = "/var/www/eaccelerator"

  In the first line enter the path printed out during the install. In the last line you could enter a directory for the eAccelerator admin tool, if you want to use it.

• Create the cache directory:

  mkdir /var/cache/eaccelerator
  chown www-data.www-data /var/cache/eaccelerator

• Restart you Apache!

  /etc/init.d/apache2 restart

There are a lot of setting in the ini file. The whole list and the description of them could be found here:  Ini-settings.

To check if everything is working open up a page on the server that contains the “php_info();” command. There should be some thing like this:

eAccelerator

Enjoy the speed!