在Scala中阻塞关键字

问题描述

未来（blocking（blockingCall（））和阻塞（Future（blockingCall（））之间有什么区别？这两个都定义在 scala.concurrent ._

What's the difference between Future(blocking(blockingCall())) and blocking(Future(blockingCall()))? Both of these are defined in scala.concurrent._

我看过和其他一些。

I've explained blocking more in depth in this answer.

REPL示例：

import java.util.concurrent.Executors
import scala.concurrent._
val ec = scala.concurrent.ExecutionContext.Implicits.global
val executorService = Executors.newFixedThreadPool(4)
val ec2 = ExecutionContext.fromExecutorService(executorService)

def blockingCall(i: Int): Unit = { Thread.sleep(1000); println("blocking call.. " + i) }

// Spawns enough new threads in `ec` to handle the 100 blocking calls
(0 to 100) foreach { i => Future(blocking(blockingCall(i)))(ec) }

// Does not spawn new threads, and `ec2` reaches thread starvation
// execution will be staggered as threads are freed
(0 to 100) foreach { i => Future(blocking(blockingCall(i)))(ec2) }

// `blocking` does nothing because the `Future` is executed in a different context,
// and `ec2` reaches thread starvation
(0 to 100) foreach { i => blocking(Future(blockingCall(i))(ec2)) }

// `blocking` still does nothing, but `ec` does not know to spawn new threads (even though it could)
// so we reach thread starvation again
(0 to 100) foreach { i => blocking(Future(blockingCall(i))(ec)) }

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