High Performance WordPress

Barry Abrahamson

Matt Mullenweg

July 22, 2007

WordCamp 2007 – San Francisco, CA

The Problem

• Serve as many users as possible with a reasonable amount of resources

Un-tuned LAMP Stack

• Linux, Apache 2, PHP 4 or 5, MySQL 4.1 or 5.0

• 8 requests/sec

• 691,200 pageviews/day

• Enough for > 99% WP installations

Alternative PHP Cache (APC)

• http://pecl.php.net/package/APC

• 12 requests/second

• 1,036,800 pageviews/day

• 50% performance increase

WP-Cache• http://mnm.uib.es/gallir/wp-cache-2/

• 300 requests/sec

• 25,920,000 pageviews/day

• 25x increase!!!!!

• Possible gotcha– http://markjaquith.wordpress.com/2006/02/13/adventures-with-w

p-cache2-apc/

Apache Alternatives

• High concurrency

• Majority (90%) of requests on a page are static

• Litespeed, lighttpd, apache + fcgi, proxy

PHP 5 – Just for fun

• Same as PHP 4 without APC

• Same as PHP 4 with APC 3.0.14

• Using APC from CVS, PHP5 is 15% faster than PHP4

When one isn’t enough

• Move the database to a second server (or 50)

• HyperDB

• Load balancing

HyperDB

Load Balancing

• Hardware or software?

• Pound– http://www.apsis.ch/pound/

• Thousands of requests/sec

• Layer 7

Caching

• Memcache– http://www.danga.com/memcached/

• Varnish– http://varnish.linpro.no

• WP-Cache alternatives

WordPress.com

• Over 1.2 million blogs

• 10+ million pageviews/day (dynamic)

• 40+ million hits/day (static + dynamic)

• 7,000+ database queries/second

• 80,000+ memcache calls/second

• http://wordpress.com/stats/

Questions