Synchronize死锁

た入场券 2022-05-15 01:50 237阅读 0赞

### Synchronize死锁 ###

双方互相持有，对方的锁  
导致，程序无法继续执行

package com.bjsxt.base.sync006;
    
    /** * 死锁问题，在设计程序时就应该避免双方相互持有对方的锁的情况 * */
    public class DeadLock implements Runnable { 
    
        private String tag;
        private static Object lock1 = new Object();
        private static Object lock2 = new Object();
    
        public void setTag(String tag) {
            this.tag = tag;
        }
    
        @Override
        public void run() {
            if (tag.equals("a")) {
                synchronized (lock1) {
                    try {
                        System.out.println("当前线程 : " + Thread.currentThread().getName() + " 进入lock1执行");
                        Thread.sleep(2000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    synchronized (lock2) {
                        System.out.println("当前线程 : " + Thread.currentThread().getName() + " 进入lock2执行");
                    }
                }
            }
            if (tag.equals("b")) {
                synchronized (lock2) {
                    try {
                        System.out.println("当前线程 : " + Thread.currentThread().getName() + " 进入lock2执行");
                        Thread.sleep(2000);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                    synchronized (lock1) {
                        System.out.println("当前线程 : " + Thread.currentThread().getName() + " 进入lock1执行");
                    }
                }
            }
        }
    
        public static void main(String[] args) {
    
            DeadLock d1 = new DeadLock();
            d1.setTag("a");
            DeadLock d2 = new DeadLock();
            d2.setTag("b");
    
            Thread t1 = new Thread(d1, "t1");
            Thread t2 = new Thread(d2, "t2");
    
            t1.start();
            try {
                Thread.sleep(500);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            t2.start();
        }
    
    }

运行  
![这里写图片描述][70]

[70]: /images/20220515/e4fea0cc89ab4427a1af63ec5d8f9093.png