Screaming Fast Wordpress

Dan Collis-PuroBerkman Center for Internet & Societyhttp://blogs.law.harvard.edu/djcpdjcp@cyber.law.harvard.edu

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

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

MLAPW

●MySQL●Linux●Apache●PHP●Wordpress

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

Linux

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

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

PHP

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

Good / bad apc

Good Bad

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

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

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

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.

Random Tools

●ab + bash●firebug●yslow●Siege●htop●apachetop●mysqltop●EXPLAIN select

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/djcpdjcp on the twitterzdjcp@cyber.law.harvard.edudan@collispuro.comhttp://delicious.com/djcp - more specifically:http://delicious.com/djcp/screamingfastwp