java多线程安全的计数器

1.示例代码

package com.multithread;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.atomic.AtomicInteger;

/**
 * @author: liminghui
 * @date: 2020/11/21 10:19
 * @version: 1.0
 * @description:
 */
public class Counter2 {
    static AtomicInteger atomicInteger = new AtomicInteger(0);
    static int count = 0;
    static final CountDownLatch COUNT_DOWN_LATCH = new CountDownLatch(10);

    public static void main(String[] args) throws InterruptedException {

        ExecutorService executorService = Executors.newFixedThreadPool(10);
        for (int i = 0; i < 10; i++) {
            Runnable runnable = new Runnable() {
                public void run() {
                    for (int j = 0; j < 10000; j++) {
                        count++;
                        // safeCount();
                        atomicInteger.incrementAndGet();
                    }
                    // 完成一个线程任务计数器减一
                    COUNT_DOWN_LATCH.countDown();
                }
            };
            executorService.execute(runnable);
        }
        // 等待所有线程执行完成
        COUNT_DOWN_LATCH.await();
        executorService.shutdown();

        System.out.println(count);
        System.out.println(atomicInteger.get());
    }

    /**
     * 使用CAS实现线程安全的计数器
     */
    private void safeCount() {
        for (; ; ) {
            int i = atomicInteger.get();
            boolean suc = atomicInteger.compareAndSet(i, ++i);
            if (suc) {
                break;
            }
        }
    }

    /**
     * 非线程安全的计数器
     */
    private void count() {
        count++;
    }
}

2.注意计数器的使用，COUNT_DOWN_LATCH.countDown();的位置，是在run方法最后

3.运行结果

32914
100000

本文地址：https://blog.csdn.net/liminghui4321/article/details/109892815