1. Screaming Fast Wordpress
Dan Collis-Puro
Berkman Center for Internet & Society
http://blogs.law.harvard.edu/djcp
djcp@cyber.law.harvard.edu

2. Me
●Dev/sysadmin for 12 years
●Pro linux admin 9 years
●Perl / mod_perl / postgres / mysql / ruby / rails /
php
●Mostly scrappy non-profits
●Geek-of-all-trades at Berkman (
http://cyber.law.harvard.edu)
●http://blogs.law.harvard.edu/
●Help manage many servers and
apps

3. Goals
●Use minimum resources to fulfill requests
●Survive the slashdot/digg effect
●Unobtrusive
●Easy to tune
●Optimize for different platforms / audiences
●If you hit the app server, you've failed
●If you MUST hit the app server, do
what's reasonable to minimize
resources

4. MLAPW
●MySQL
●Linux
●Apache
●PHP
●Wordpress

5. MySQL
●Optimize tables (with mysqlcheck and a cron job)
●Bump up query cache
●Tune key buffers
●mysqltuner.pl / tuning-primer.sh
●Might want more indexes, depending
●mytop
●Slow query log
●(meh) Clean out options table
●(meh) Clean out revisions / old spam
●(plugin) debug-queries

6. Linux
●RAM
●Never use swap
●Fast disk, database on its own spindles
●Fast network
●stat() kills you on network filesystems

7. Apache
●Use a reverse proxy
●Keepalive on frontend, no keepalive on backend
●Enable mod_deflate
●Set a sane MaxClients setting
●Use a lighter-weight frontend server – nginx!
●Use frontend proxy caching
●apachetop

8. PHP
●Enable opcode cache
●Make sure you allocate enough
shared RAM
●Consider not allowing stat()s

9. Good / bad apc
Good Bad

10. Wordpress
●Two major audiences: logged in and not.
●WP-SuperCache, W3 Total Cache
●Memcached is not a panacea.
●Nor is the WP object cache.
●Disable unused plugins
●CDN for media delivery

11. Our Problem
●750+ live blogs, some heavily trafficked and quite
large
●Not too many simulateously auth'd users
●MANY spiders. Freakin' spiders!
●Mini-DDOSs each week
●ENORMOUS corpus of URLs to cache
●RSS feeds don't use feedburner

12. Our Solution
●nginx as a caching front-end proxy
●No plugins
●4 lines of code to the wordpress core
●Very flexible caching rules
●Able to cache for both audiences (sorta)
●Able to cache EVERYTHING. Period.
●Handles gzipping and logging
●Able to kill bad 'bots

13. Results
●Almost NO problems since implementation
●Atom feed from 6/sec to 2500/sec (network test)
●Atom feed from 3.95/sec to ~7000/sec (local test)
(apache 3500 / sec)
●DOUBLED network throughput (?)
●Halved memory requirements
●Able to rip out all wordpress-level
customizations and plugins.
Except one.

15. Random Tools
●ab + bash
●firebug
●yslow
●Siege
●htop
●apachetop
●mysqltop
●EXPLAIN select

16. Photo credits:
Characters:
http://www.flickr.com/photos/goopymart
Background:
http://www.flickr.com/photos/roll_initiative
I ♣ you! Get in touch:
http://blogs.law.harvard.edu/djcp
djcp on the twitterz
djcp@cyber.law.harvard.edu
dan@collispuro.com
http://delicious.com/djcp - more specifically:
http://delicious.com/djcp/screamingfastwp