java多线程死锁及死锁问题排查

Posted 2021-07-07 500年

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java多线程-死锁及死锁问题排查

1、死锁是什么

在这里插入图片描述

2、死锁测试

import java.util.concurrent.TimeUnit;

public class DeadLockDemo {

	public static void main(String[] args) {
		String lockA = "A";
		String lockB = "B";

		new Thread(new MyThread2(lockA, lockB)).start();
		new Thread(new MyThread2(lockB, lockA)).start();
	}

}

class MyThread2 implements Runnable {

	private String lockA;
	private String lockB;

	public MyThread2(String lockA, String lockB) {
		this.lockA = lockA;
		this.lockB = lockB;
	}

	@Override
	public void run() {
		synchronized (lockA) {
			System.out.println(Thread.currentThread().getName() + " 锁" + lockA + " -> 想拿锁" + lockB);

			try {
				TimeUnit.SECONDS.sleep(2);
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			synchronized (lockB) {
				System.out.println(Thread.currentThread().getName() + " 锁" + lockB + " -> 想拿锁" + lockA);
			}
		}
	}

}