周练习 7

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发布于: 2020 年 11 月 08 日
性能压测的时候，随着并发压力的增加，系统响应时间和吞吐量如何变化，为什么？
一个良好的系统随着并发压力的增加,系统响应时间会先缓慢增加,但随着系统压力接近或超过极限,系统的响应时间的增加量将迅速增多,响应时间-并发压力的曲线将呈现类似指数的形状;
吞吐量则先随着并发压力的增加而快速增加,然后到达拐点吞吐量增长放缓,接着达到顶点,之后随着并发压力的增加反而下降;
系统资源是有限的,最开始并发压力低的时候系统可能还有不少空闲资源,随着并发压力的上升这些资源将逐渐利用,但达到峰值后就无法同时处理这么多请求了,不做处理的话一般会阻塞后续的请求
用你熟悉的编程语言写一个 Web 性能压测工具，输入参数：URL，请求总次数，并发数。输出参数：平均响应时间，95% 响应时间。用这个测试工具以 10 并发、100 次请求压测 www.baidu.com。
Task类:
package com.example.week7;
import com.example.redis.JedisFactory;
import redis.clients.jedis.Jedis;
import java.net.URL;
import java.net.URLConnection;
public class TestUrlTask implements Runnable{
    private static final String RESULT_COLLECTION_KEY = "testUrlResult";
    private String url;
    private int accessNumber;
    @Override
    public void run() {
        try {
            Jedis jedis = JedisFactory.prepareJedis();
            for (int i = 0; i < accessNumber; i++) {
                URL targetUrl = new URL(url);
                URLConnection urlConnection = targetUrl.openConnection();
                long startTime = System.currentTimeMillis();
                urlConnection.connect();
                long endTime = System.currentTimeMillis();
                long cost = endTime - startTime;
                String currentKey = this.getCurrentMember(i);
                jedis.zadd(RESULT_COLLECTION_KEY, cost, currentKey);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            Thread.currentThread().interrupt();
        }
    }
    private String getCurrentMember(int i) {
        Thread currentThread = Thread.currentThread();
        String currentThreadName = currentThread.getName();
        long currentThreadId = currentThread.getId();
        String currentKey = String.format("%s_%s_%d", currentThreadName, currentThreadId + "", i);
        return currentKey;
    }
    public TestUrlTask(String url, int accessNumber) {
        this.url = url;
        this.accessNumber = accessNumber;
    }
}
测试类:
package com.example.week7;
import com.example.redis.JedisFactory;
import redis.clients.jedis.Jedis;
import java.util.Set;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
public class TestUrl {
    public static void main(String[] args) throws Exception {
        String url = args[0];
        int concurrentNumber = Integer.parseInt(args[1]);
        int eachAccessNumber = Integer.parseInt(args[2]);
        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(concurrentNumber, concurrentNumber, 3, TimeUnit.SECONDS, new LinkedBlockingQueue());
        for (int i = 0; i < concurrentNumber; i++) {
            TestUrlTask testUrlTask = new TestUrlTask(url, eachAccessNumber);
            threadPoolExecutor.execute(testUrlTask);
        }
        while (true) {
            if(threadPoolExecutor.getActiveCount() == 0) {
                break;
            }
        }
        threadPoolExecutor.getQueue().clear();
        threadPoolExecutor.shutdown();
        showResult();
        System.out.println("all done");
    }
    private static void showResult() {
        Jedis jedis = JedisFactory.prepareJedis();
        Set<String> zrange = jedis.zrange(TestUrlTask.RESULT_COLLECTION_KEY, 0, -1);
        Long count = jedis.zcard(TestUrlTask.RESULT_COLLECTION_KEY);
        Double costTime = 0D;
        Long counter = 0L;
        Long targetTitlePosition = count / 100 * 95;
        String targetTitleMember = "";
        for (String member : zrange) {
            Double zscore = jedis.zscore(TestUrlTask.RESULT_COLLECTION_KEY, member);
            costTime += zscore;
            counter++;
            if (counter.equals(targetTitlePosition)) {
                targetTitleMember = member;
            }
        }
        Double averageCostTime = costTime / count;
        Double titleCostTime = jedis.zscore(TestUrlTask.RESULT_COLLECTION_KEY, targetTitleMember);
        System.out.println("平均响应时间:"+ averageCostTime +" ;95% 响应时间: " + titleCostTime);
    }
}
控制台输出取样:
平均响应时间:21.405 ;95% 响应时间: 23.0
all done
﻿
发布于: 2020 年 11 月 08 日阅读数: 59
何毅曦

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周练习 7

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