1. Memory-efficient and fast websites Malcolm Tredinnick

2. Setup ● Web application ● Single machine (or small number) ● No real budget ● Brains, time, enthusiasm

3. Big-time Operations What do they do?

4. Big-time Operations (2) ● Vertical design / horizontal scaling ● Session management ● Geographical scaling ● Staffing

5. Vertical Design

6. Horizontal Scaling

7. Approach ● What is going on? ● What does it mean? ● What can be changed? ● What are the trade-offs? – TANSTAAFL!

8. “Now” and “Later” ● Perspective ● Realism ● Balance

9. Useful Tools ● Server log analysis – logwatch – awstats ● Stat collection – rrdtool – Cricket (for example)

10. Useful Tools (2) ● Live analysis – vmstat – pcat (part of Coroner's Toolkit) – wget/curl – firebug / YSlow – ab (Apache bench) – /proc/ /maps

11. The Players ● Processor ● Memory ● Disk ● Network traffic ● Timeliness ● Reliability ● Consistency ● $$$

12. Weapon Selection ● Web servers ● Databases ● Caches ● Proxies

13. Caching ● On disk – Pre-generated – on-demand ● In memory ● HTTP layer

14. Caching Gotchas ● Coherency ● The thundering herd problem – Objects take non-zero time to create

15. Distributed Workloads ● Static / dynamic split – The DIY approach – Amazon web services (S3, EC2) ● Content delivery networks (CDN) – YUI – Google code

16. In Practice ● Scaling discontinuities ● Post hoc analysis ● Forwards-looking design

17. Prepare For The Worst ● Failure levels – Complete meltdown – Partial unavailability – Inconsistencies ● Slashdot effect ● Mitigating versus solving

18. Learning Is Continuous ● Learn from the big(-ish) guys – livejournal, wikipedia, twitter, slashdot ● HTTP Caching – Mark Nottingham's blog ● Be interested in data structures ● Read documentation ● Experiment

19. Programs ● Web servers and interfaces – Apache ● modpython ● modwsgi – mighttpd – CherryPy – WSGI (Python interface spec) ● Nginx – reverse proxy ● squid

20. Programs (2) ● Databases – PostgreSQL – MySQL – SQLite ● Memcached – in-memory, distribute caching

21. Resources ● Writing minimal Apache config – FIXME! ● The Coroner's toolkit, etc – http://porcupine.org/ http://porcupine.org/