多线程死锁问题

死锁调试

示例代码

package com.windy.me;

public class DeadLockThread {

    public static void main(String[] args) throws InterruptedException {
        Object obj1 = new Object();
        Object obj2 = new Object();
        Object obj3 = new Object();

        Thread t1 = new Thread(new SyncThread(obj1, obj2), "t1");
        Thread t2 = new Thread(new SyncThread(obj2, obj3), "t2");
        Thread t3 = new Thread(new SyncThread(obj3, obj1), "t3");

        t1.start();
        Thread.sleep(5000);
        t2.start();
        Thread.sleep(5000);
        t3.start();

    }
}
class SyncThread implements Runnable{
    private Object obj1;
    private Object obj2;

    public SyncThread(Object o1, Object o2){
        this.obj1=o1;
        this.obj2=o2;
    }
    @Override
    public void run() {
        String name = Thread.currentThread().getName();
        System.out.println(name + " acquiring lock on "+obj1);
        synchronized (obj1) {
         System.out.println(name + " acquired lock on "+obj1);
         work();
         System.out.println(name + " acquiring lock on "+obj2);
         synchronized (obj2) {
            System.out.println(name + " acquired lock on "+obj2);
            work();
        }
         System.out.println(name + " released lock on "+obj2);
        }
        System.out.println(name + " released lock on "+obj1);
        System.out.println(name + " finished execution.");
    }
    private void work() {
        try {
            Thread.sleep(30000);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}

**注意：运行上面死锁程即可。

操作细节

1. 第一步

   打开黑窗

2. 后续步骤如下图