死锁AB-BA问题

Posted 2022-03-12 shaozhen

AB-BA经常是造成多线程死锁的最大元凶，具体表现为线程I先后去拿锁A与锁B，然而当去拿锁B时发现已经被另一个线程II拿走，然而线程II拿到锁B后又需要锁A，于是两个线程互相等待在成死锁

 1 public class Main
 2      public static void main(String[] args)
 3         System.out.println("演示开始");
 4            new Thread(()->
 5              A.a();
 6            ).start();
 7            new Thread(()->
 8              B.b();
 9            ).start();
10      
11 
12      static class A
13         public static synchronized void a()
14             try
15                 Thread.sleep(3000);    
16             catch(Exception e)
17                 e.printStackTrace();
18             
19             
20 
21             System.out.println("我拿到锁a了，锁b快到碗里来！");
22 
23             B.b();
24         
25      
26 
27      static class B
28         public static synchronized void b()
29             System.out.println("我拿到锁b了，锁a快到碗里来！");
30             try
31                 Thread.sleep(3000);    
32             catch(Exception e)
33                 e.printStackTrace();
34             
35             A.a();
36         
37      
38