Scala 2.9和演员平行收藏

他们解决不同的问题.演员善于解决 task parallel problems.虽然并行集合很好地解决了 data parallel problems.我不认为它们是相互排斥的 – 您可以在actor中使用并行集合并包含actors的并行集合.

编辑 – 快速测试：
即使是像演员通知循环一样简单的好处.

在下面的代码中,我们向一个actor注册表注册了一百万个actor,该注册表必须通知他们一个事件.

非平行通知循环(注册表foreach {})在我的机器(4核2.5 GHz笔记本)上平均需要2.8秒.
当使用并行收集循环(registry.par.foreach {})需要1.2秒并使用所有四个内核.

import actors.Actor

case class Register(actor: Actor)
case class Unregister(actor: Actor)
case class Message( contents: String )

object ActorRegistry extends Actor{
  var registry: Set[Actor] = Set.empty

  def act() {
    loop{
      react{
        case reg: Register => register( reg.actor )
        case unreg: Unregister => unregister( unreg.actor )
        case message: Message => fire( message )
      }
    }
  }

  def register(reg: Actor) { registry += reg }

  def unregister(unreg: Actor) { registry -= unreg }

  def fire(msg: Message){
    val starttime = System.currentTimeMillis()

    registry.par.foreach { client => client ! msg } //swap registry foreach for single th

    val endtime = System.currentTimeMillis()
    println("elapsed: " + (endtime - starttime) + " ms")
  }
}

class Client(id: Long) extends Actor{
  var lastmsg = ""
  def act() {
    loop{
      react{
        case msg: Message => got(msg.contents)
      }
    }
  }
  def got(msg: String) {
    lastmsg = msg
  }
}

object Main extends App {

  ActorRegistry.start
  for (i <- 1 to 1000000) {
    var client = new Client(i)
    client.start
    ActorRegistry ! Register( client )
  }

  ActorRegistry ! Message("One")

  Thread.sleep(6000)

  ActorRegistry ! Message("Two")

  Thread.sleep(6000)

  ActorRegistry ! Message("Three")

}