NiceThreads.scala

import com.twitter.util.{Duration, Future, FuturePool, Try}
import java.util.concurrent.{LinkedBlockingQueue, ThreadPoolExecutor, TimeUnit}

val poolSize = 4
val queue = new LinkedBlockingQueue[Runnable]()
val executor = new ThreadPoolExecutor(poolSize, poolSize, 0L, TimeUnit.MILLISECONDS, queue)
val futurePool = FuturePool(executor)

def doWork(n: Int): Int = {
  Thread.sleep(1000)
  n
}

def niceThread(n: Int): Future[Int] = (futurePool {
  doWork(n)
  futurePool {
    doWork(n)
  }
}).flatten

val data1F = niceThread(1)
val data2F = niceThread(2)
val data3F = niceThread(3)
val data4F = niceThread(4)

val resultF =
  for {
    data1 <- data1F
    data2 <- data2F
    data3 <- data3F
    data4 <- data4F
  } yield {
    data1 + data2 + data3 + data4
  }

resultF.get(Duration.fromSeconds(3))

Is the key to this working that the outer future pool call is returning a future, and so flatten returns the inner future?