java多线程 CAS原子引用AtomicReference

Posted 2021-07-07 500年

java多线程 CAS原子引用AtomicReference

CAS：comparAndSet 比较并交换 与乐观锁原来相同。
背景：ABA问题

实战

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

// 原子引用
public class CASDemo {

public static void main(String[] args) {

	// 注意、注意、注意：Integer处在具体的业务中，应为对象。切勿使用Integer。因为超过127就会一直false。详见：Integer
	// -128~127 == 问题
	AtomicStampedReference<Integer> atomicStampedReference = new AtomicStampedReference<>(1, 1);

	new Thread(() -> {
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

		boolean compareAndSet = atomicStampedReference.compareAndSet(1, 2, atomicStampedReference.getStamp(),
				atomicStampedReference.getStamp() + 1);
		System.out.println(Thread.currentThread().getName() + " " + compareAndSet);
		boolean compareAndSet2 = atomicStampedReference.compareAndSet(2, 1, atomicStampedReference.getStamp(),
				atomicStampedReference.getStamp() + 1);
		System.out.println(Thread.currentThread().getName() + " " + compareAndSet2);
	}).start();

	new Thread(() -> {
		try {
			TimeUnit.SECONDS.sleep(2);
		} catch (InterruptedException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		boolean compareAndSet = atomicStampedReference.compareAndSet(1, 2, atomicStampedReference.getStamp(),
				atomicStampedReference.getStamp() + 1);
		System.out.println(Thread.currentThread().getName() + " " + compareAndSet);
		boolean compareAndSet2 = atomicStampedReference.compareAndSet(2, 1, atomicStampedReference.getStamp(),
				atomicStampedReference.getStamp() + 1);
		System.out.println(Thread.currentThread().getName() + " " + compareAndSet2);
	}).start();

}

}

特别鸣谢：狂神说Java老师的无私奉献

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