Scaling Scala at Twitter by Marius Eriksen (Twitter)


Scala, cufp2010

Rockdove is the backend service that powers the geospatial features on and the Twitter API ("Twitter Places"). It provides a datastore for places and a geospatial search engine to find them. To throw out some buzzwords, it is:

  • a distributed system
  • realtime (immediately indexes updates and changes)
  • horizontally scalable
  • fault tolerant

Rockdove is written entirely in Scala and was developed by 2 engineers with no prior Scala experience (nor with Java or the JVM). We think the geospatial search engine provides an interesting case study as it presents a mix of algorithm problems and "classic" scaling and optimization issues. We will report on our experience using Scala, focusing especially on:

  • "functional" systems design
  • concurrency and parallelism
  • using a "research language" in practice
  • when, where and why we turned the "functional dial"
  • avoiding mutable state