Shouldn't we add a test where we create a EssentialAction/EssentialFilter:

  def index = EssentialAction { rh =>
    Accumulator.done(Ok(Thread.currentThread().getName))
  }

while before it was netty-event-loop-NUMBER and now it will be application-akka.actor.default-dispatcher-NUMBER?

And another question might also remain, if we change the ExecutionContext to Trampoline inside the Action (DefaultActionBuilder instead of relying on a user passed one?) / Filter Code, since I guess else it will switch Threads more than necessary? Guess the best way would be merging it and check if there is a "serious" performance hit in prune!?

@schmitch Yeah, we can see what prune says. I think we try to avoid thread switching already using trampoline in most places, which is how we ran into this problem in the first place.

I'll add a test as well to make sure the right thread is being used.

LGTM