Default dispatcher size

After migrating my actors-based application from 2.5 to 2.6, I got bad performance on load. Reading the migration manual, I suspect the changes in dispatchers are causing it:

  1. default dispatcher size factor reduced to 1.0
  2. A new internal dispatcher was added
    It is mentioned that I can modify it via configuration. So just to make I’m doing it the right way.
    Are these the lines I need to add to my config file in order to restore the 2.5 behavior:
actor.internal-dispatcher =
actor.default-dispatcher.fork-join-executor.parallelism-factor = 3.0

You should not change the internal-dispatcher unless you know exactly what the application is running, otherwise it will starve Akka internal tasks and defeat the purpose of the internal dispatcher.

The change that matters for you is probably the parallelism-factor. You can try changing that.