并发模拟的四种方式

Postman：Http请求模拟工具

Apache Bench（AB）：Apache附带的工具，测试网站性能

如输入命令：ab -n 1000 -c 50 http://localhost:8081/test

JMeter：Apache组织开发的压力测试工具

安装方法看下文【参考】部分

• 创建线程组：
  
  
• 添加Http测试
  
  
• 添加测试结果查看监视器
  
  

代码：Semaphore、CountDownLatch等

package com.dai.concurrency;

import com.dai.concurrency.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;

/**
 * author daioo
 * create 2019-04-13 21:26
 */

@Slf4j
public class ConcurrencyTest {

    public static int clientTotal = 5000;

    public static int threadTotal = 50;

    public static int count = 0;

    public static void main(String[] args) throws Exception{
        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();
        System.out.println(count);
    }

    private static void add() {
        count++;
    }
}

输出结果是4989，不是5000，是线程不安全的

参考

JMeter在Mac下的安装