參考

• 狂神說

介紹

自旋鎖的定義：當一個執行緒嘗試去獲取某一把鎖的時候，如果這個鎖此時已經被別人獲取(佔用)，那麼此執行緒就無法獲取到這把鎖，該執行緒將會等待，間隔一段時間後會再次嘗試獲取。這種採用迴圈加鎖 -> 等待的機制被稱為自旋鎖(spinlock)。看完你就明白的鎖系列之自旋鎖
java.util.concurrent.atomic.AtomicStampedReference：AtomicStampedReference維護一個物件引用以及一個整數“標記”，可以原子方式更新。

程式碼

package lock;

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

/**
 * @Author 夏秋初
 * @Date 2022/3/5 11:51
 */
public class SpinLock {
    public static AtomicStampedReference<Thread> atomicStampedReference = new AtomicStampedReference(null, 0);
    /**
     * 自旋鎖的簡單實現
     */
    public static void lock(){
        while (!atomicStampedReference.compareAndSet(null, Thread.currentThread(), 0, 1)){

        }
        System.out.println(Thread.currentThread().getName() + "加鎖成功");
    }
    public static void unLock(){
        System.out.println(Thread.currentThread().getName() + "解鎖成功");
        atomicStampedReference.compareAndSet( Thread.currentThread(), null, 1, 0);
    }

    public static void main(String[] args) {
        new Thread(()->{
            SpinLock.lock();
            try{
                try {
                    TimeUnit.SECONDS.sleep(2);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }finally {
                SpinLock.unLock();
            }
        },"A").start();
        new Thread(()->{
            SpinLock.lock();
            try{
                try {
                    TimeUnit.SECONDS.sleep(2);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }finally {
                SpinLock.unLock();
            }
        },"B").start();
    }
}