Scaling a Web Service
BarCamp HK 2007
Leon Ho, Stepcase Limited

Objective
• Sustaining the scale of the traffic
• Zero downtime
• High performance
• Squeezing every juice from the server

Why?
• Stepcase Lifehack (http://www.lifehack.org):
• 1 million visits per month
• 2 million pageviews per month
• Those does not include images,
javascript, stylesheets
• We’ve done 5400 new connections per
min

1. Hardware

Stage 1
Web Server DB
Shared Hosting

Stage 2
Web Server DB

Stage 3
Slave
DB
Master
Web Server
DB
Slave
DB

Stage 4
Master
DB
Web Server Master
DB
MySQL Cluster

Stage 5
App Server
Master
DB
Load
App Server
Balancer Master
DB
MySQL Cluster
App Server

Servers
• Stage 2
• Running 2 servers;
each with 4 cores
and 4GB RAM
• Exposing only one
server to public
network

Remember the point is
to stay in early stages.

2. Reduce Connections

Static Files
• Moves out to a separate server
• Consider Amazon S3
• Image - Decrease the number of images
you need to load
• CSS Spites
• Use Firebug to benchmark

Amazon S3
• We moved our static images to S3
• files.lifehack.org CNAME
s3.amazonaws.com
• use cronjob and s3sync to keep them in
sync
• next, move js, css, and post images out

Feed
• 60,000 subscriptions daily
• We use external provider - Feedburner

3. Reduce File Size

Javascript
• Compress the javascript
• JSMin, Dojo ShrinkSafe, Packer,YUI
Compressor
• http://compressorrater.thruhere.net

4. Optimize and Cache

Web & DB Server
• Web: Moved to Lighttpd
• DB: MySQL. Increase query cache, max
connection and wait timeout

Cache
• Cache, Cache, and Cache
• Page level (wp-cache)
• DB queries (memcache, or any object
caches)
• PHP opcode - xcache, e-accelerator

What else?
• Eliminate bottleneck
• Hard drive > Memory > CPU
• Reduce Abuse and Spam

Next
• Adding more comprehensive monitoring
• Munin
• More scaling - this time - on Rails

Questions?
Visit Us:
Contact Me:
http://www.stepcase.com
leon@stepcase.com
http://www.lifehack.org
P.S. We are hiring!