HowScalaFutureWorks.scala

gistfile1.scala

import scala.concurrent._
import ExecutionContext.Implicits.global
import scala.concurrent.duration._


val is = 1 to 10 toList
def db = s"${Thread.currentThread}"
def f(i: Int) = Future {
  println(db + s" -> \t I'm ${i} -> \t I start to sleep")
  Thread.sleep(1*1000)
  println(db + s" -> \t I'm ${i} -> \t I wake from sleep")
  i * 100
}.map {
  x =>
    println(db + s" => \t I'm ${x} => \t I start to sleep")
    Thread.sleep(1*1000)
    println(db + s" => \t I'm ${x} => \t I wake from sleep")
    i
}

val theFuture = Future.traverse(is)(f _)
Await.result(theFuture, 100.seconds)

An advanced version can be viewed at https://gist.github.com/hanfeisun/9f2a486f0c7f75d67ac3