Personally I think not a lot. Before JDK 8 maybe, but since then Java has steadily been improving in every direction.
There was a certain phase in my career where it seemed everybody I was working for or with had attempted to do parallel calculations in Scala with actors and found they were only using 2 of the 8 CPUS they had and that they still had race conditions. Your choice was to waste two days trying to make it work in Scala or to rewrite it with ExecutorService and have it done in 20 minutes.
