scalaのFutureの並列に実行されない書き方とされる書き方 - Qiita

import scala.concurrent.Future import scala.concurrent.ExecutionContext.Implicits.global val start = System.currentTimeMillis for{ _ <- Future(Thread.sleep(3000)) _ <- Future(Thread.sleep(3000)) } yield println("the process time is " + (System.currentTimeMillis - start) + " msec.") // the process time is 6141 msec. import scala.concurrent.Future import scala.concurrent.ExecutionContext.Implicits.g