Anatomy of a PHP Request

PHP was originally designed to work with Apache http as mod_php. The state of web technology has come a long way since then, but PHP still has the same fundamental architecture. Understanding how PHP works is very important when trying to deal with issues of scale and performance.

We can break down some of the topics as follows:

• PHP module startup and shutdown
• PHP request startup and shutdown (compare/contract with the way Ruby/Python/Node work)
• Opcode Cache
• C Extensions
• Session management
• HTTP request parsing
• HTTP response buffering
• Requests from PHP: SQL, NoSQL, memcache and other APIs
• threads in PHP
• mod_php vs php-fpm
• Long lived requests