The rewrite was from Ruby to Scala, though far more importantly, it was a re-architecting. And there are zero regrets. Without it, Twitter wouldn't exist anymore.
Sorry, you're exactly correct. It was Ruby -> Scala and Java.
To be precise, according to Tony Pritezis from Twitter, Scala is the main language, Java is next, Ruby was still in use in 2014 but migrating away, C/C++ and Python for some specific tasks. He did also talk about some of the problems of using Scala, and I seem to recall someone saying that Scala may be less favoured at Twitter in the future.
Sorry, you're exactly correct. It was Ruby -> Scala and Java.
To be precise, according to Tony Pritezis from Twitter, Scala is the main language, Java is next, Ruby was still in use in 2014 but migrating away, C/C++ and Python for some specific tasks. He did also talk about some of the problems of using Scala, and I seem to recall someone saying that Scala may be less favoured at Twitter in the future.