使用Junit测试hashTable与ConcurrentHashMap性能

1.数据量比较打的时候CurrentHashMap的效率要更高

package com.ydlclass.JUnit;

import com.ydlclass.collection.CountDownLatchTest;
import org.junit.Test;

import java.util.Hashtable;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.CountDownLatch;

public class PerformanceTest {
    //HashTable与ConcurrentHashMap
    @Test
    public void testHashTable() throws InterruptedException {
        final Map<Integer,Integer> map = new Hashtable<>(50000);
        final CountDownLatch count = new CountDownLatch(50);
        System.out.println("----Hashtable开始工作----");
        long start = System.currentTimeMillis();
        for (int i = 0; i < 50; i++) {//多线程执行
            int k = i;
            new Thread(() -> {
                for (int j = 0; j < 1000000; j++) {//每个线程执行10000次的插入操作
                    map.put(k + j,j);//保证插入的键不同
                }
                count.countDown();
            }).start();
        }

        count.await();//等待50个线程分别插入10000条数据后的最大时间；
        long end = System.currentTimeMillis();
        System.out.println("----Hashtable执行结束----");
        System.out.println("所用时间为：" + (end - start));

    }

    @Test
    public void ConcurrentTest() throws InterruptedException {
        final ConcurrentHashMap<Integer,Integer> concurrentHashMap = new ConcurrentHashMap<>(50000);
        final CountDownLatch count = new CountDownLatch(50);
        System.out.println("----ConcurrentHashMap开始工作----");
        long start = System.currentTimeMillis();

        for (int i = 0; i < 50; i++) {
            int k = i;
            new Thread(() ->{
                for (int j = 0; j < 1000000; j++) {
                    concurrentHashMap.put(k + j,j);
                }
                count.countDown();
            }).start();
        }
        count.await();
        long end = System.currentTimeMillis();
        System.out.println("-----ConcurrentHashMap结束工作----");
        System.out.println("所用时间为:" + (end - start));
    }
}

----ConcurrentHashMap开始工作----

-----ConcurrentHashMap结束工作----

所用时间为:2902

----Hashtable开始工作----

----Hashtable执行结束----

所用时间为：4311