scala Future 死锁 - 修复了 4 线程池

Question

Q1：为什么会死锁？

implicit val ec = ExecutionContext.fromExecutor(Executors.newFixedThreadPool(4))

val futures = List( Future{1} )

val result: Future[List[Int]] = Future.sequence(futures)

Await.ready(result, Duration.Inf)

当池中有 5 个 future/threads（超过 4 个）时，我预计会有类似的行为。

Answer 1

也许这不是僵局。我认为主线程正在等待线程池退出。尝试调用执行程序服务的 .shutdown()。

import java.util.concurrent.Executors
import scala.concurrent.duration.Duration
import scala.concurrent.{ExecutionContext, Await, Future}

object DeadLockSample1 {
  def main(args: Array[String]) {
    val pool =  Executors.newFixedThreadPool(4)
    implicit val ec = ExecutionContext.fromExecutor(pool)
    Future{1}
    pool.shutdown() // without this, it won't exit.
  }
}

scala Future 死锁 - 修复了 4 线程池

scala Future deadlock - fixed 4-thread pool

scala

deadlock

future