• 当使用receive时，程序为每个actor都单独创建一个线程，如没有接收到消息，该线程也会一直保持等待，不可以其他任务复用。
• 当使用react时，actor不会单独占用线程，只有当接收到消息程序才会为该actor分配线程，非常节省资源。

但毫无疑问，使用react时每接受到一条消息都需要重新分配线程和进行初始化工作，所以会有一定的延迟，这在实际应用中也需要进行权衡。
以下代码展示了上述的区别：WRActor和LRActor分别代表了两种接收消息的模式，WRActor接收每条消息都新建了一个线程，而LRActor接收所有消息都复用了相同的线程。

import scala.actors.Actor

object Sub6 extends App {

  1 to 30 foreach{ i =>
    new WRActor().start() ! "Hello"
  }
  1 to 30 foreach{ i =>
    new LRActor().start() ! "Hello"
  }
}

class WRActor extends Actor{
  override def act(): Unit = {
    while(true){
      receive{
        case "Hello" => println("WR: "+Thread.currentThread())
      }
    }
  }
}

class LRActor extends Actor{
  override def act(): Unit = {
    loop{
      react{
        case "Hello" => println("LR: "+Thread.currentThread())
      }
    }
  }
}

WR: Thread[ForkJoinPool-1-worker-11,5,main]
WR: Thread[ForkJoinPool-1-worker-7,5,main]
WR: Thread[ForkJoinPool-1-worker-5,5,main]
WR: Thread[ForkJoinPool-1-worker-9,5,main]
WR: Thread[ForkJoinPool-1-worker-13,5,main]
WR: Thread[ForkJoinPool-1-worker-3,5,main]
WR: Thread[ForkJoinPool-1-worker-15,5,main]
WR: Thread[ForkJoinPool-1-worker-1,5,main]
WR: Thread[ForkJoinPool-1-worker-23,5,main]
WR: Thread[ForkJoinPool-1-worker-27,5,main]
WR: Thread[ForkJoinPool-1-worker-31,5,main]
WR: Thread[ForkJoinPool-1-worker-17,5,main]
WR: Thread[ForkJoinPool-1-worker-21,5,main]
WR: Thread[ForkJoinPool-1-worker-19,5,main]
WR: Thread[ForkJoinPool-1-worker-25,5,main]
WR: Thread[ForkJoinPool-1-worker-29,5,main]
WR: Thread[ForkJoinPool-1-worker-47,5,main]
WR: Thread[ForkJoinPool-1-worker-45,5,main]
WR: Thread[ForkJoinPool-1-worker-59,5,main]
WR: Thread[ForkJoinPool-1-worker-39,5,main]
WR: Thread[ForkJoinPool-1-worker-53,5,main]
WR: Thread[ForkJoinPool-1-worker-37,5,main]
WR: Thread[ForkJoinPool-1-worker-51,5,main]
WR: Thread[ForkJoinPool-1-worker-35,5,main]
WR: Thread[ForkJoinPool-1-worker-49,5,main]
WR: Thread[ForkJoinPool-1-worker-63,5,main]
WR: Thread[ForkJoinPool-1-worker-43,5,main]
WR: Thread[ForkJoinPool-1-worker-57,5,main]
WR: Thread[ForkJoinPool-1-worker-41,5,main]
WR: Thread[ForkJoinPool-1-worker-55,5,main]


LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]
LR: Thread[ForkJoinPool-1-worker-33,5,main]