Demo Volatile不保证原子性

import com.ma.juc.annoations.NotThreadSafe;
import lombok.extern.slf4j.Slf4j;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Semaphore;

@Slf4j
@NotThreadSafe
public class CountExample4 {
    //请求总数
    public static int clientTotal = 5000;
    //同时并发执行的线程数
   public static int threadTotal = 200;
   //volatile
   //不保证内存的子性,也不能保证线程安全
   //使用的场景 ： volatile boolean xxxx;
   public static volatile int count = 0;

    public static void main(String[] args) throws InterruptedException {
        ExecutorService executorService = Executors.newCachedThreadPool();
        final Semaphore semaphore = new Semaphore(threadTotal);
        final CountDownLatch countDownLatch = new CountDownLatch(clientTotal);
        for(int i = 0;i < clientTotal ; i++)
            executorService.execute(() -> {
                try {
                    semaphore.acquire();
                    add();
                    semaphore.release();
                } catch (Exception e) {
                   log.error("exception",e);
                }
                countDownLatch.countDown();
            });
        countDownLatch.await();
        executorService.shutdown();
        log.info("count:{}",count);
    }
    public static void add(){

        count++;
        // 实际执行的过程
        //1、从主存读count
        //2、+1
        //3、把count写回主存
    }
}