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标题: 多线程运行代码问题 [打印本页]
作者: 咕咕猫    时间: 2013-9-21 17:12
标题: 多线程运行代码问题
本帖最后由 咕咕猫 于 2013-9-21 17:57 编辑

class Test implements Runnable
{
private int tick =100;
Object obj = new Object();
public void run()
{
  while (tick>0)
  {
   synchronized(obj)//同步代码块
   {
    if(tick>0)
    {
     try//休眠10毫秒
     {
      Thread.sleep(10);
     }
     catch (Exception e)
     {
     }
     System.out.println(Thread.currentThread().getName()+":"+tick);
     tick--;
    }
   }
  }
}
}
class Demo
{
public static void main(String[] args)
{
  Test t = new Test();
  Thread t1 = new Thread(t);//创建两个线程
  Thread t2 = new Thread(t);
  t1.start();
  t2.start();
}
}
为什么我运行的结果都是线程Thread-0在运行呢 试了N次都是 这个按理来说不应该吧 求指教
作者: 路边小色狼    时间: 2013-9-21 17:33
本帖最后由 路边小色狼 于 2013-9-21 17:36 编辑
  1. class Test implements Runnable
  2. {
  3. private int tick =100;
  4. Object obj = new Object();
  5. public void run()
  6. {
  7.   while (tick>0)
  8.   {

  10.     if(tick>0)
  11.     {
  12.      try//休眠10毫秒
  13.      {
  14.       Thread.sleep(10);
  15.      }
  16.      catch (Exception e)
  17.      {
  18.      }
  19.      System.out.println(Thread.currentThread().getName()+":"+tick);
  20.      tick--;
  21.     }

  23.   }
  24. }
  25. }
  26. class meiju
  27. {
  28. public static void main(String[] args)
  29. {
  30.   Test t = new Test();
  31.   Thread t1 = new Thread(t);//创建两个线程
  32.   Thread t2 = new Thread(t);
  33.   t1.start();
  34.   t2.start();
  35. }
  36. }
复制代码
你锁住了当然只能走一个线程。你把锁去掉不就好了
你是不是想问为什么都是线程 0在走啊，。线程1也会走的，你多试几次，我有试过
作者: （0.0）’    时间: 2013-9-21 17:34
我调试好像没有啥大问题啊，只是你运行多次就出来了
每次结果都不一样。
  1. class Test implements Runnable {
  2.         private int tick =100;
  3.         Object obj = new Object();
  4.         public void run(){
  5.                 while(tick>0){
  6.                         synchronized(obj){
  7.                                 if (tick>0) {
  8.                                         try {
  9.                                                 Thread.sleep(10);
  10.                                         }
  11.                                         catch (Exception e) {
  12.                                         }
  13.                                         System.out.println(Thread.currentThread().getName()+":"+tick);
  14.                                         tick--;
  15.                                 }
  16.                         }
  17.                
  18.                 }
  19.         }
  20. }
  21. class Demo {
  22.         public static void main(String[] args){
  23.                 Test t = new Test();

  25.                 Thread t1 = new Thread(t);
  26.                 Thread t2 = new Thread(t);
  27.                 t1.start();
  28.                 t2.start();
  29.         }
  30. }
复制代码
作者: 咕咕猫    时间: 2013-9-21 17:51
路边小色狼 发表于 2013-9-21 17:33
你锁住了当然只能走一个线程。你把锁去掉不就好了
你是不是想问为什么都是线程 0在走啊，。线程1也会走的， ...

这个锁的位置应该不会影响交替运行的吧 我试了好多次都是线程0在运行 没出现过线程1运行的情况
作者: 咕咕猫    时间: 2013-9-21 17:53
本帖最后由 咕咕猫 于 2013-9-21 17:54 编辑
（0.0）’ 发表于 2013-9-21 17:34
我调试好像没有啥大问题啊，只是你运行多次就出来了
每次结果都不一样。 ...

你运行的时候是两个线程都运行了吗 为什么我试了好多次都只是同一个线程0运行 1线程运行情况都没出现过  人品不会这么差吧

作者: 简单ai...    时间: 2013-9-21 17:54
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复制代码
没发现有什么问题呀，你多运行几次看看，我复制你的代码运行如下，（cpu分配资源是不规则的）
作者: 咕咕猫    时间: 2013-9-21 17:56
简单ai... 发表于 2013-9-21 17:54
没发现有什么问题呀，你多运行几次看看，我复制你的代码运行如下，（cpu分配资源是不规则的） ...

看来真是人品问题啊
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E:\abc>java Demo
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E:\abc>javac 18.java
E:\abc>javac 18.java
E:\abc>java Demo
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E:\abc>
作者: （0.0）’    时间: 2013-9-21 18:05
咕咕猫 发表于 2013-9-21 17:53
你运行的时候是两个线程都运行了吗 为什么我试了好多次都只是同一个线程0运行 1线程运行情况都没出现过   ...

哈哈，是这样的，你多运行N次，就想老毕说的一句话，你就当本年度最悲惨线程就是那个没出现的问题了。
作者: 简单ai...    时间: 2013-9-21 18:07
你可以换个版本eclipse测试，或者配置不同的jar包试试，我测试是通过的，完全复制你的代码，就改了下类名
作者: loading……99.9    时间: 2013-9-21 18:12
带没问题，因为你只运行了100次，对于高速运行的cpu，100次可能也就在一个时间片里就运行完了，你改成运行1000，10000次或者更多试试。
作者: 冯晓骏    时间: 2013-9-21 18:33
tick改成10000慢慢跑，最悲惨线程也有登场机会



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