多线程案例1：奇偶交替输出

尝试写了一个奇偶交替输出的demo，记录一下问题：

原来的线程类是如下：

 1 package com.future.day0521;
 2 
 3 public class demo1 {
 4     public static int num = 1;
 5     public static Object js = new Object();
 6     public static Object os = new Object();
 7 
 8     static class odd implements Runnable{
 9 
10         public void run() {
11             while (true){
12                 synchronized (js){
13                     synchronized (os){
14                         System.out.println("odd:"+num);
15                         num++;
16                         os.notifyAll();
17                         try {
18                             js.wait();
19                         } catch (InterruptedException e) {
20                             e.printStackTrace();
21                         }
22                     }
23                 }
24                 Thread.yield();
25             }
26         }
27     }
28 
29     static class even implements Runnable{
30 
31         public void run() {
32             while (true){
33                 synchronized (os){
34                     synchronized (js){
35                         System.out.println("even:"+num);
36                         num++;
37                         js.notifyAll();
38                         try {
39                             os.wait();
40                         } catch (InterruptedException e) {
41                             e.printStackTrace();
42                         }
43                     }
44                 }
45                 Thread.yield();
46             }
47         }
48     }
49 
50     public static void main(String[] args) throws InterruptedException {
51         Thread t1 = new Thread(new odd());
52         Thread t2 = new Thread(new even());
53         t1.start();
54         Thread.sleep(10);
55         t2.start();
56     }
57 }
View Code

运行结果是，卡在了odd:1，使用visualvm软件，看到dump文件中是even线程blocking了，卡在了获取js的锁上，然后把odd类修改一下

static class odd implements Runnable{
        public void run() {
            while (true){
                synchronized (js){
                    synchronized (os){
                        System.out.println("odd:"+num);
                        num++;
                        os.notifyAll();
                    }
                    try {
                        js.wait();
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
                Thread.yield();
            }
        }
    }
View Code

将js.wait移动到外面，代码就可以正常执行了。深入原因没有考虑，后面有时间研究一下

posted @ 2019-05-22 09:55  一天到晚想名字  阅读(461)  评论(0)  编辑  收藏  举报