scala - Future 是否有新线程？

Question

像下面这样实现的 future 是否有新线程？显然不是(见下面的输出)。为什么？如果我希望我的代码在新线程上运行，我应该怎么做？

package MyTest

import com.twitter.util._

import scala.language.postfixOps

object Test {

  def test1 = Future {
    println("BeforeTest", Thread.currentThread())
    Thread.sleep(5000)
    println("AfterTest", Thread.currentThread())
  }

  def test2 = test1 onSuccess { case _ => println("Future on success") }

  def main(args: Array[String]): Unit = {

    println("main", Thread.currentThread())
    test2
    println("main123", Thread.currentThread())
  }
}

输出:

(main,Thread[run-main-0,5,run-main-group-0])

(BeforeTest,Thread[run-main-0,5,run-main-group-0])

(AfterTest,Thread[run-main-0,5,run-main-group-0])

成功的 future

(main123,Thread[run-main-0,5,run-main-group-0])

Answer 1

您使用的是 Twitter future ，而不是 Scala future 。默认情况下，Twitter future 不是多线程的。你必须使用 FuturePool (使用您选择的线程池将其传递给 ExecutorService)

未经测试的示例(我希望足够简单:)):

val executor = Executors.newFixedThreadPool(4)
val pool = FuturePool(executor)

def test1 = pool { 
  println("BeforeTest", Thread.currentThread())
  Thread.sleep(5000)
  println("AfterTest", Thread.currentThread())
}

def test2 = test1 onSuccess { case _ => println("Future on success") }

def main(args: Array[String]): Unit = {

  println("main", Thread.currentThread())
  test2
  println("main123", Thread.currentThread())

  executor.shutdown()
}