In Scala, is there a way to tell which execution context you are running in?

Question

In Scala, if I know that a piece of code is running in a Future, is there a way of finding out in which ExecutionContext the Future resides? Eg, so that I can write out this information to a log.

Don't worry, I don't want to do anything nefarious. I just want the information for debugging.

Answer 1

Viktor Klang had this to say in a comment:

Any sensible ExecutionContext ought to name its threads appropriately, then it shows up in logs using Thread.currentThread().getName().

I think that this is just what I need.

Thanks, Viktor!

Answer 2

Not clear what do you want, but if you want to get the implicit variable in Future context, you can do it like:

  def main(args: Array[String]): Unit = {
    helloWorld()
    fooBar()
  }
  def fooBar(): Unit = {
    import scala.concurrent.ExecutionContext.Implicits.global
    Future {
      println(implicitly[ExecutionContext].hashCode())
      "foo bar"
    }
  }
  def helloWorld(): Unit = {
    implicit val ec = ExecutionContext.fromExecutor(Executors.newFixedThreadPool(10))
    Future {
      println(implicitly[ExecutionContext].hashCode())
      "Hello World"
    }
  }

use implicitly with the implicit type to get the implicit variable.