是否等待Scala Future块线程？ [英] Does a wait on Scala Future block thread?

问题描述

当我等待获取Scala Future的结果时，它的行为是否更像接收或反应，即它会阻塞线程，还是在结果可用后安排继续？

When I wait for result of Scala Future, does it behave more like receive, or like react, i.e. does it block a thread, or schedules a continuation after result if available?

推荐答案

是的，在stdlib中，它阻塞了线程，并同步等待结果。如果要对期货应用延续传递样式，则必须使用Akka或Scalaz，它们允许直接在框中添加对期货完成的挂钩。

Yes, in stdlib it blocks the thread, and synchronously waits for results. If you want to apply continuation-passing style to futures, you'd have to use Akka or Scalaz that allow adding hooks on futures completion straight from the box.

阿卡语：

val f1 = Future { Thread.sleep(1000); "Hello" + "World" }

val f2 = f1 map { _.length }

f2 foreach println //Done asynchronously and non-blocking

与 Scalaz ：

scala> val f1 = promise {Thread.sleep(1000); "Hello" + "World"}
f1: scalaz.concurrent.Promise[java.lang.String] = scalaz.concurrent.Promise$$anon$1@1f7480

scala> val f2 = f1 map{str => str.length}
f2: scalaz.concurrent.Promise[Int] = scalaz.concurrent.Promise$$anon$1@1d40442

scala> f2.map(println)
10
res5: scalaz.concurrent.Promise[Unit] = scalaz.concurrent.Promise$$anon$1@116ad20

这篇关于是否等待Scala Future块线程？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！