Tuesday, February 26, 2008

Drupal + CentOS + optimization

I've been working through various optimization issues today and thought i'd share them with my future self and anyone else who reads this.

mod_deflate

I'd heard that getting apache to gzip your non-compressed data was a good idea and thought I was probably already doing that with my default apache2 setup on CentOS 4.4. What I learned was that:
  1. For apache2, the relevant module is mod_deflate (it used to be mod_gzip)
  2. My CentOS included the apache module by default, but didn't enable it. I did that according to the excellent documentation on the apache web site.
  3. I found a test site, which says that the html is now about 25% of what it was, saving me bandwidth and increasing the apparent response of my sites.

wim leers

I found a great article about drupal optimization here: improving drupal's page loading performance. He refers to a firefox plug-in developed by Yahoo that looks like a great tool, as well as a list of key issues to analyse for any site, and how those can be addressed in various ways by Drupal. My key understanding here is that php code + mysql optimization is only a small part of the user experience of a fast site.

APC + mysql query cache

Yes, I use APC as my php cache and love it. And i've tuned mysql somewhat to have a reasonable query cache. For handling sudden bursts of traffic (e.g. gpo.ca during the election), this combination is awesome - it means most traffic, even for complex pages, is handled by a bare minimum of cached php and cache mysql calls. Great for the server scaling traffic anyway.

css + javascript

Wim's article above refers to this issue, but it's worth thinking about on it's own. I'd like to use the javascript compressor for all my custom and contrib module javascript and stick it at the end of the page html. And using Drupal's built in css combine/compress mechanism seems more important now - i'd been ignoring it.

apache2

The default apache2 setup for CentOS isn't optimized for Drupal - it comes with a lot of extra modules. I haven't done a rigourous paring yet, but would like to report on what I can remove when i do eventually manage that. Also - i'd like to consider having separate apache instances for https and civicrm so that it's more streamlined. I'm also using fastcgi for sympa, which would be nice to split out.