Java线程ABA问题

import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicReference;
import java.util.concurrent.atomic.AtomicStampedReference;

public class ABADemo {
    static AtomicReference<Integer> atomicReference = new AtomicReference<>(100);
    static AtomicStampedReference<Integer> atomicStampedReference=
            new AtomicStampedReference<>(100,1);

    public static void main(String[] args) {

        System.out.println("==============ABA问题的产生================");
        new Thread(() -> {
            atomicReference.compareAndSet(100, 101);
            atomicReference.compareAndSet(101, 100);
        }, "t1").start();

        new Thread(() -> {
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            System.out.println(atomicReference.compareAndSet(100,2018)+"\t"
            +atomicReference.get());
        }, "t2").start();

        System.out.println("==============ABA问题的解决================");

        new Thread(()->{
            int stamp=atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName()
            +"\t第一次的版本号:"+stamp);

            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            atomicStampedReference.compareAndSet(100,101,
                    atomicStampedReference.getStamp(),atomicStampedReference.getStamp()+1);
            System.out.println(Thread.currentThread().getName() + "\t第二次版本号" + atomicStampedReference.getStamp());

            atomicStampedReference.compareAndSet(101,100,
                    atomicStampedReference.getStamp(),atomicStampedReference.getStamp()+1);
            System.out.println(Thread.currentThread().getName() + "\t第三次版本号" + atomicStampedReference.getStamp());
        },"t3").start();

        new Thread(()->{
            int stamp=atomicStampedReference.getStamp();
            System.out.println(Thread.currentThread().getName()
                    +"\t第一次的版本号:"+stamp);

            try {
                TimeUnit.SECONDS.sleep(3);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

            boolean result=atomicStampedReference.compareAndSet(100,2018,
                    stamp,stamp+1
            );
            System.out.println(Thread.currentThread().getName() + "\t修改成功否?" + result +
                    "\t当前最新实际版本号:" + atomicStampedReference.getStamp());

            System.out.println(Thread.currentThread().getName() + "\t当前实际最新值:" +
                    atomicStampedReference.getReference());
        },"t4").start();
    }
}

  

posted @ 2020-03-04 22:31  石shi  阅读(400)  评论(0编辑  收藏  举报