[aelzeiny]

Nobody will suggest Java, but honestly Java. Java has pretty great flexibility when it comes down to concurrency. It sets the standard which all the other languages have to compete with.

Apart from that, I like languages and frameworks that scale out of their box and into the world of distributed systems. Elixir is very cool, because the concept of distribution with message passing is built into the core of the language. Alternatively, Scala's Akka Framework operates on a similar concept of passing messages to Actors. My bias here is that I don't like to deal with very large super-computers, and would rather have multiple smaller machines that are allowed to blackout occasionally. This is especially relevant for websockets because the stateful connection to a client can be made on any single machine in a cluster, but the state itself is (often) global.

[dimgl]

I'm going to sound very elitist, but there is 0 chance I'm going to use Java. Aside from my own bad experiences with Java in a professional setting, .NET Core is now a thing, and I'm actually very experienced with C#, so I'd rather just use C# at that point rather than become proficient with Java and the JVM.