2dehands.be is the market leader for classified ads in Belgium. You don't get to become big without proper performance of your site. In this talk I will focus on the solutions we came up with in terms of frontend performance, which tools are available and how to interpret the results. The second part I will also give insight on backend tools like Varnish, Memcached, Redis. Especially which performance related problems you might encounter when amount of users and pageviews increase.

1. Tuning a Big Classifieds Site
Enno van Amerongen
Technical Lead @ 2dehands.be

2. Introduction
- Who am I
- 2dehands
- TTY
- Startups: Zwapp.com, EU1.tv, Paypool.com

3. Tuning a Big Classifieds Site
- 3 Year Journey
- Consistently Growing
- Dev & Ops

4. Performance KPIs
- Availability
- Average page load times
- Pages per visit per browser
- Bounce Rate
- User complaints / User experience

5. Business KPIs
- Availability
- Unique/returning visitors
- Revenue
- User complaints / User experience
- And much, much more

6. What did the KPIs say?
- Availability problems @ peak time
- User Complaints!

7. Investigate
- Server / Cluster statistics using Munin
- Manually check servers
- Google Analytics
- Use tools

8. Tools
- webpagetest.org
- Google Pagespeed / Critical Path Explorer
- YSlow
- Browser tools / plugins

9. Prioritized Problem Overview
- Capacity issues
- Barely functioning Image Cluster
- Unoptimized Frontend

10. Solutions
- Scale up and out
- more servers
- more bandwidth
- more cores
- more disks
- more memory

11. Introduce HTTP Cache using Varnish
- Replace frontend load-balancer (pound)
- Cache every asset forever
- But test it first!

12. Varnish Gotcha's
- Use tmpfs for the shared memory file
- Do not deploy on the wrong server
- Use -smalloc (in memory cache)
- Files never change (LRU works)
- Normalize compression

13. Varnish Full Deployment Result
- 80% Cache hitrate
- 1000s of requests per second
- Doesn't break a sweat
- No more user complaints
- Faster pageload times

15. Unoptimized Frontend
- No combination of static assets
- No minification
- No compression of javascript
- No asynchronous loading of external scripts

16. Minimize requests and filesize
- Split head/tail
- Combine and minimize css and javascript
- Yahoo UI Compressor (or any other)
- Use compression

17. Asynchronous script loading/execution
- Facebook Connect
- Google Analytics
- Google Adsense
- Others (and still some to do)

19. The Repeat View

20. Result
- Average pageload ~2.5 sec
- No more complaints
- Lots more returning visitors
- More revenue
- Decreased bounce rate

21. Are we done yet?
- Introduce async scriptloader (LABjs or HEADjs)
- CSS Sprites
- Reduce TTFB on Apache backends
- and ...

22. Still Time?

23. Memcached vs Redis
- Memcached is running great for years
- Currently testing Redis
- But what about the client?

24. Any questions?
Or contact me: enno@2dehands.be / enno@tty.nl

25. Thanks for your attention!