Drupal bootstrap early page cache
The previous article in this series focused on phase 1 of the Drupal bootstrap process (DRUPAL_BOOTSTRAP_CONFIGURATION). This article will now focus on the second phase - DRUPAL_BOOTSTRAP_EARLY_PAGE_CACHE. The early page cache phase is one that might not accomplish much for some Drupal sites, but for some others can play an important role in improving a site's overall performance by minimizing latency when delivering content to a user's browser. This is accomplished by caching already rendered pages for anonymous users (i.e. haven't logged in). This phase is run early in the bootstrap process as it doesn't rely on any later bootstrap phases (used to gather content and render pages) and its purpose is to keep latency to a minimum - in other words the sooner it executes, the faster a user receives the requested content. There are two forms of caching with Drupal: non-database and database. The early page cache relies on non-database mechanisms, such as file syst...