[3]

5. 源代码：

// 核心调度程序
public class mythread {
  public mythread() {  }
  public static void main(String[] args) {
    M m = new M();
  }
}
// A 任务线程
class A extends Thread {
  public static boolean dead = false;
  M m;
  A(M m){
    m = m;
    start();
  }
  public void run(){
     try{
      for(int i=-3;i<= 5;i++){
        int j=1/i;   // 人为设置过程中陷阱
        dead = !dead;  // 活动状态
        System.out.println("i=" + i + ": status=" + dead);
        try{
          sleep(2000);
        }
        catch(InterruptedException ie){
          System.out.println("A is Interrupted!");
        }
      }
      m.Keepchecking = false;  //A 正常结束后关闭监控线程
      System.out.println("A is Ending M");
    }
    catch(Exception e){
      System.out.println("A become Exception!");
    }
  }
}
// 监控线程
class M extends Thread{
  public static boolean Keepchecking = true;  // 持续监控标志
  boolean laststatus;     //保存上次监控状态
  int maydeadtimes = 0;  //监控线程可能死亡的计数器
  int maydeadtimeout = 3;//定义判断线程死亡的边界条件
  int deadtimes = 0;     //监控线程死亡次数的计数器
  int deadtimeout = 3;   //定义判断线程不正常的边界条件
  A a;
  M(){start();}
  public void run(){
    schedule();
    while(Keepchecking){
      laststatus = a.dead;
      try{
        sleep(2000);
      }
      catch(InterruptedException e){
        System.out.println("M is Interrupted!");
      }
      System.out.println("M read A status = " + a.dead);
      if(laststatus == a.dead ){
        if(++maydeadtimes >= maydeadtimeout){
          if(++deadtimes >= deadtimeout){
            System.out.println("Alert! A is unstable, M will stop it");
            a = null;
            break;
          }
          else{
            System.out.println( "A is deaded!");
            schedule();
            System.out.println("M is restarting A!\n____________________________\n");
          }
        }
      }
      else{
        maydeadtimes = 0;
      }
    }
  }
  private void schedule(){
    A a = new A(this);
  }
}

    [3] 

【责编:Peng】

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