Practical use of futures? Ie, how to kill them?

Question

Futures are very convenient, but in practice, you may need some guarantees on their execution. For example, consider:

import scala.actors.Futures._

def slow         


        

Answer 1

I think the reason Future can't simply be "killed" is exactly the same as why java.lang.Thread.stop() is deprecated.

While Future is running, a Thread is required. In order to stop a Future without calling stop() on the executing Thread, application specific logic is needed: checking for an application specific flag or the interrupted status of the executing Thread periodically is one way to do it.

Answer 2

Futures are intended to be used in settings where you do need to wait for the computation to complete, no matter what. That's why they are described as being used for slow running functions. You want that function's result, but you have other stuff you can be doing meanwhile. In fact, you might have many futures, all independent of each other that you may want to run in parallel, while you wait until all complete.

The timer just provides a wait to get partial results.