深入理解Java死锁的实现与避免-优快云博客

本文链接：https://blog.youkuaiyun.com/weixin_45546060/article/details/108325208

本文详细探讨了Java中死锁的概念，通过实例分析展示了如何在多线程环境中造成死锁，并提出了解决和预防死锁的策略。通过对资源请求顺序的调整以及超时和回滚机制的应用，可以有效防止死锁问题的发生。

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// 模拟Java死锁实现 ---老师的写法
public class DeadLock {

	public static void main(String[] args) {
		DeadLock dl = new DeadLock();
		dl.myRun();
	}
	
	public void myRun() {
		MyLock ml = new MyLock();
		
		Thread t1 = new Thread(ml,"线程1");
		Thread t2 = new Thread(ml,"线程2");
		
		t1.start();
		t2.start();
	}
	
	public class MyLock implements Runnable{
		private boolean flag = true;
		private Object key1 = new Object();
		private Object key2 = new Object();
		
		
		public void run() {
			if(flag) {
				flag = false;
				synchronized (key1) {
					String name = Thread.currentThread().getName();
					System.out.println(name + "进入了----");
					
					try {
						Thread.sleep(1000);
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
					
					synchronized (key2) {
						String n = Thread.currentThread().getName();
						System.out.println(n + "进入了----");
					}
				}
			}
			else {
				
				flag = true;
				
				synchronized (key2) {
					String name = Thread.currentThread().getName();
					System.out.println(name + "进入了----");
					
					try {
						Thread.sleep(1000);
					} catch (InterruptedException e) {
						e.printStackTrace();
					}
					
					synchronized (key1) {
						String n = Thread.currentThread().getName();
						System.out.println(n + "进入了----");
					}
				}
			}
		}
	}
}
// 我的写法 ----------------

/**
 * 死锁的实现
 */
//1. 创建runnable接口实现类
public class DeadLock implements Runnable {
    private boolean flag = true;
    private Object key1 = new Object();
    private Object key2 = new Object();

    //2. 重写run()方法  编写线程体
    @Override
    public void run() {
        if (flag) {
            flag = false;
            synchronized (key1) {
                String name = Thread.currentThread().getName();
                System.out.println("线程" + name + "-- in");
                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                synchronized (key2) {
                    String n = Thread.currentThread().getName();
                    System.out.println("线程" + n + "-- in");
                }

            }
        } else {
            flag = true;

            synchronized (key2) {
                String name = Thread.currentThread().getName();
                System.out.println("线程" + name + "-- in");

                try {
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }

                synchronized (key1) {
                    String n = Thread.currentThread().getName();
                    System.out.println("线程" + n + "-- in");
                }
            }
        }
    }

    public static void main(String[] args) {
        DeadLock dl = new DeadLock();
        Thread t1 = new Thread(dl, "线程1");
        Thread t2 = new Thread(dl, "线程2");
        t1.start();
        t2.start();
    }
}