Blocking calls in Akka Actors

Question

As a newbie, I am trying to understand how actors work. And, from the documentation, I think I understand that actors are objects which gets executed in sync mode and also t

Answer 1

You are right to be thinking about the Thread Pool if you are considering doing blocking calls in Akka. The more blocking you do, the larger the Thread Pool you will need. A completely Non-Blocking system only really needs a pool of threads equal to the number of CPU cores of your machine. The reference configuration uses a pool of 3 times the number of CPU cores on the machine to allow for some blocking:

    # The core pool size factor is used to determine thread pool core size
    # using the following formula: ceil(available processors * factor).
    # Resulting size is then bounded by the core-pool-size-min and
    # core-pool-size-max values.
    core-pool-size-factor = 3.0

source

But you might want to increase akka.default-dispatcher.fork-join-executor.core-pool-size-factor to a higher number if you do more blocking, or make a dispatcher other than the default specifically for blocking calls with a higher fork-join-executor.core-pool-size-factor

WRT what is the best way to do blocking calls in Akka. I would recommend scaling out by making multiple instances of the actors that do blocking calls and putting a router infront of them to make them look like a single actor to the rest of your application.