Twitter moves from Rails to Java

A colorful feather up Rails’ cap is on the ground now. Twitter has decided to go away from RoR in favor of Java, this time for their entire search stack. Earlier in 2008-09, they decided to move their message queue back-end from ruby to Scala (a Java Platform) and now it is the time for their front-end to move to Java as well.
They have built a scalable platform called Blender that uses Java NIO based server (Netty) to be efficient in the face of heavy incoming traffic, replaced MySQL with a Java based Lucene search engine, created an engine that parallelizes execution of multiple backend services with dependency management and more. With this setup there is a 3X drop in search latencies and can scale to 10X more requests per machine.

Wow, that is quite an achievement. Could this mean that Java is a better platform than Rails for high scalability needs? Even if that is the case, for simpler scenarios, the beauty of RoR out-weighs Java’s performance.

They say that this change will enable them to rapidly iterate on search features in the coming months. That along with the news that Twitter has hired 25 more employees kinda tells that Java’s code base is practically more maintainable than equivalent Ruby code – at least when the code base is huge and the team size is large. Or that could mean that this time they really put a lot of thought into designing a maintainable system than when they started out. But for smaller team size and code base, RoR is still an unbeaten champion.