As is sometimes the case, people start with the wrong abstraction (thread pool) and then optimize it.

Java/Scala streams look like they would solve most of the problems in the post on their own.

e.g. Java streams

http://radar.oreilly.com/2015/02/java-8-streams-api-and-para...

    private void runParallel() {
      trades
      .stream()
      .parallel().forEach(t->doSomething(t) );
    }

Java/Scala has a hierarchy of concurrency abstractions, from high level to low level:

Streams, Parallel collections, Futures, Actors, Fork/Join, ExecutionContext/ExecutorService, Threadpools, Threads, synchronized, Barriers, Atomic values and many more.