当Scala"Future"被垃圾收集时会发生什么？

Question

说我有一个Stream相当昂贵的计算.我可以通过编写类似的东西轻松创建一个"提前计算"的线程

import scala.actors.Futures._
val s = future { stream.size }

如果我然后抛弃对此的引用,该Future线程是否会被垃圾收集器杀掉？

Answer 1

不.该线程属于调度程序.在任何情况下,调度程序都会引用正文未完成的Future(这种情况发生在a.start()),因此在完成之前不会进行垃圾回收.

object Futures {

  /** Arranges for the asynchronous execution of `body`,
   *  returning a future representing the result.
   *
   *  @param  body the computation to be carried out asynchronously
   *  @return      the future representing the result of the
   *               computation
   */
  def future[T](body: => T): Future[T] = {
    val c = new Channel[T](Actor.self(DaemonScheduler))
    val a = new FutureActor[T](_.set(body), c)
    a.start()
    a
  }
}