多线程编程：一个指令重排序引发的chaos

先贴出正确的代码：

 1 package com.xiaobai.thread.main;
 2 
 3 import lombok.extern.slf4j.Slf4j;
 4 
 5 @Slf4j
 6 public class ThreadMain {
 7 
 8     private volatile static int ticket;
 9 
10     private static class RunningTask implements Runnable{
11 
12         public RunningTask(boolean proOrSell) {
13             this.proOrSell = proOrSell;
14         }
15 
16         private boolean proOrSell = true;//如果为静态，会被实例共享
17 
18         public void run() {
19             while (true) {//只同步需要同步的代码，while(true)不能放在同步里面！！否则除非线程自己wait(),永远不会轮到其他线程！！
20                 synchronized (RunningTask.class) {
21                     proOrSell();
22                 }
23             }
24         }
25 
26         private void proOrSell() {
27             if(proOrSell) {
28                 ticket++;
29                 log.info("Tickets/Pro:" + ticket);
30                 RunningTask.class.notifyAll();
31                 if(ticket >= 1000) {
32                     try {
33                         System.out.println("--------------------------------------------------------------------------------------------------------------------------------------->Pro Wait!!!!!");
34                         RunningTask.class.wait();//持有锁的本线程等待
35                     } catch (InterruptedException e) {
36 
37                     }
38                 }
39             }else {
40                 System.out.println(Thread.currentThread().getName() + " take control!");
41                 if(ticket <= 100) {
42                     try {
43                         System.out.println(Thread.currentThread().getName() + " <=100!");
44                         System.out.println("XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX==>Sell Wait!!!!");
45                         RunningTask.class.wait();
46                     } catch (InterruptedException e) {
47 
48                     }
49                 }else {
50                     ticket--;
51                     log.info("Tickets------->Sell:" + ticket);
52                     System.out.println(Thread.currentThread().getName() + " decrease tickets!");
53                     if(ticket <= 500) {
54                         RunningTask.class.notifyAll();
55                     }
56                 }
57             }
58         }
59     }
60 
61     private static void proOrSell() {
62         Runnable task1 = new RunningTask(true);
63         Runnable task2 = new RunningTask(false);
64         Thread thread1 = new Thread(task1);
65         Thread thread2 = new Thread(task2);
66         Thread thread3 = new Thread(task2);
67         Thread thread4 = new Thread(task2);
68         thread1.start();
69         try {
70             Thread.sleep(3000);
71         } catch (InterruptedException e) {
72 
73         }
74         thread2.start();
75         thread3.start();
76         thread4.start();
77     }
78 
79     public static void main(String[] args) {
80         proOrSell();
81         while (ticket <= 0) {
82             System.out.println("------------------------------------------------------->Ticket System Broken!!!!!!");
83             System.exit(0);
84         }
85     }
86 
87 }

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