简单死锁演示

最新推荐文章于 2022-04-07 17:25:58 发布

原创最新推荐文章于 2022-04-07 17:25:58 发布 · 155 阅读

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本文详细探讨了Java中线程同步导致的死锁现象，通过`TestDeadLock`和`test5`示例，展示了如何通过synchronized关键字和并发执行引发的资源争夺问题。关键部分涉及了对象锁的使用和线程间的依赖关系，旨在帮助读者理解并发编程中的问题及解决策略。

package com.yuan1.day1;

/**
 * @author QLBF
 * @version 1.0
 * @date 2021/6/16 21:15
 */
class A{}
class B{}
public class test5 {
    static A a=new A();
    static B b=new B();

    public static void main(String[] args) throws InterruptedException {
        new Thread(()->{
            synchronized (a){
                try {
                    Thread.sleep(2000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                synchronized (b){
                    System.out.println("我获得了a和b");
                }
            }
        }).start();

        Thread.sleep(1000);
        new Thread(()->{
            synchronized (b){
                synchronized (a){
                    System.out.println("我获得了b和a");
                }
            }
        }).start();
    }
}

下面这个更加简单一点：

package com.yuan.deadlock.v1;

import lombok.extern.slf4j.Slf4j;


@Slf4j(topic = "c.TestDeadLock")
public class TestDeadLock {
    public static void main(String[] args) {
        test1();
    }

    private static void test1() {
        Object A = new Object();
        Object B = new Object();
        Thread t1 = new Thread(() -> {
            synchronized (A) {
                log.debug("A lock A");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                synchronized (B) {
                    log.debug("A lock B");
                    log.debug("操作...");
                }
            }
        }, "t1");

        Thread t2 = new Thread(() -> {
            synchronized (B) {
                log.debug("B lock B");
                try {
                    Thread.sleep(500);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                synchronized (A) {
                    log.debug("B lock A");
                    log.debug("操作...");
                }
            }
        }, "t2");
        t1.start();
        t2.start();
    }
}