Obviously a JVM stack developer is going to know Java. But in this world of polyglot programming, knowing a bit of JavaScript, Ruby and Scala as well is a must. In fact, it might even make you a ...

How did Twitter handle election tweets? Less Ruby, more Java As Twitter continues to tweak Ruby performance, it moves more to JVM on servers.

Today, Twitter's software is built from a mix of Scala and ordinary Java code. A few Twitter services still run on Ruby, too, but according to Rawashdeh these are used increasingly less often.