概念：

• 是指嘗試獲取鎖的線程不會(huì)立即阻塞，而是采用循環(huán)的方式嘗試獲取鎖崇渗。
  優(yōu)點(diǎn)：減少線程上下文切換的消耗字逗。
  缺點(diǎn)：循環(huán)會(huì)消耗CPU京郑。

代碼驗(yàn)證：

package com.yy.java;
/**
* @author yuanyong:
* @version 2021年2月26日 下午4:04:22
* 類說(shuō)明   驗(yàn)證自旋鎖
*/

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


public class TestSpinLock {
    
    AtomicReference<Thread> atomicReference = new AtomicReference<>();
    
    public void mylock() {
        Thread thread  = Thread.currentThread();
        System.out.println(thread.getName()+"-->mylock");
        
        while (!atomicReference.compareAndSet(null, thread)) {
            System.out.println(thread.getName()+"-->trying get lock！");
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
        }
    
    }
    
    public void myUnlock() {
        Thread thread = Thread.currentThread();
        atomicReference.compareAndSet(thread, null);
        System.out.println(thread.getName()+"-->myUnlock");
    }

    public static void main(String[] args) {
        TestSpinLock testSpinLock = new TestSpinLock();
        
        new Thread(() -> {
            testSpinLock.mylock();
            try {
                TimeUnit.SECONDS.sleep(5); //T1占用5s
            } catch (Exception e) {
                e.printStackTrace();
            }
            testSpinLock.myUnlock();
        },"T1").start();
        
        try {
            TimeUnit.SECONDS.sleep(1);
        } catch (Exception e) {
            e.printStackTrace();
        }
        
        new Thread(() -> {
            testSpinLock.mylock();
            try {
                TimeUnit.SECONDS.sleep(1);
            } catch (Exception e) {
                e.printStackTrace();
            }
            testSpinLock.myUnlock();
        },"T2").start();
    }
}
*****************************執(zhí)行結(jié)果：**********************************
T1-->mylock
T2-->mylock
T2-->trying get lock葫掉！
T2-->trying get lock些举！
T2-->trying get lock！
T2-->trying get lock挖息！
T1-->myUnlock
T2-->myUnlock

分析：根據(jù)結(jié)果效果可以發(fā)現(xiàn)金拒，在T1線程占用鎖的5s期間兽肤，T2線程每隔1s就嘗試獲取一次鎖套腹。