Mon 07 December 2009 by Jim Purbrick

On Friday I jumped on the train to London to attend the first scalecampuk, an unconference about scalability, at the Guardian offices.

The sessions were all very interesting and mostly very relevant. I learned new things about XSS and CSRF and Django’s defences against them from Simon Willison, new things about messaging, pubsub, queues and data stores (process 1 message at a time, use message hospitals, send URLs to unavailable data that can be polled for with JavaScript and that just check memcache entries) lots about Varnish ) and it’s use at Wikia from Artur Bergman (Wikia runs off 18 apaches and 8 varnishes with 60GB of RAM and SSDs to serve 25 million pages and 950Mbps at peak, Varnish is generally better than squid ), but you need a modern kernel).

Lots of the talks were about moving storage, caching and queuing out of the application and just writing a small piece of business logic to tie them together. Against this background Alex Evans’ talk about the back end for Media Molecule’s Little Big Planet stood out like a sore thumb. Having not enjoyed using a Java web stack, Alex has just rewritten the whole of the back end as proprietary technology as a single binary in order to know the code from end to end. While it may be true that having custom physics or rendering middleware might distinguish Little Big Planet from other games, I can’t believe that custom technology to serve HTTP requests is going to be a competitive advantage. I hope Alex’s good ideas become Redis contributions rather than a maintenance nightmare and barrier to agility.

The lightning talks were also very good. Simon’s “ScaleFail” talk about the Guardian MP expenses app was hilarious (lesson: do load testing) and Gareth’s talk about Dumbo (a Python Hadoop client) was very useful.

At times it felt like the talks were suited to an ops audience, but “Dev’s should know about this!” was a regular refrain. Don’t worry: I listened and learned a lot. Thanks to everyone who made it a great day.


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