架构师训练营第七周作业

作业一

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？

对于响应时间

1. 当并发数上升的时，资源（线程数、数据库连接数、CPU、内存）使用未满时，响应时间保持稳定不变

2. 当并发数继续上升时，因系统并发导致资源等待、任务调度、CPU 等待等，任务处理时长增加，响应时间会缓慢上升

3. 当并发继续上升时，因资源不足，无法响应请求，响应时间会快速上升，达到系统崩溃点

对于吞吐量

1. 当并发数上升的时，吞吐量会达到线性增加

2. 当并发数继续上升时，吞吐量上升趋势慢慢变缓

3. 当并发继续上升时，吞吐量下降趋势慢慢增大

作业二

压测工具代码如下：

设置线程池，使用 cando 变量控制是否进行请求。

平均响应为 每次时长之和/次数

95%响应为排序后取第 95%位数

import java.math.BigInteger;

import java.util.Arrays;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import org.apache.http.client.methods.CloseableHttpResponse;

import org.apache.http.client.methods.HttpGet;

import org.apache.http.impl.client.CloseableHttpClient;

import org.apache.http.impl.client.HttpClients;

public class yace {

private static boolean cando = false;

private static volatile int threadCount = 0;

private static int totalCount = 0;

private static int [] duetime;

public static void main(String[] args) {

int total = 100;

yace yc = new yace();

yace.setTotalCount(total);

ExecutorService fixedThreadPool = Executors.newFixedThreadPool(100);

String url = "http://www.baidu.com";

for (int i = 0; i < total; i++) {

fixedThreadPool.execute(new Runnable() {

public void run() {

try {

yc.doGet(url);

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

}

});

}

yace.setCando(true);

}

public void doGet(String testUrl) throws Exception {

HttpGet httpGet = new HttpGet(testUrl);

CloseableHttpClient httpclient = HttpClients.createDefault();

CloseableHttpResponse response = null;

while (!cando) {

}

long start = System.currentTimeMillis();

// 执行请求

response = httpclient.execute(httpGet);

long end = System.currentTimeMillis();

httpclient.close();

threadCount++;

// 判断返回状态是否为 200

if (200 == response.getStatusLine().getStatusCode()) {

duetime[threadCount - 1] += (end - start);

} else {

duetime[threadCount - 1] += 999999;

System.out.println("request error"+response.getStatusLine().getStatusCode());

}

if(threadCount == totalCount) {

System.out.println(getAvgTime());

System.out.println(get95AvgTime());

}

}

public static long getAvgTime(){

long totalDuetime = 0;

for(int i = 0; i < totalCount; i++) {

totalDuetime += duetime[i];

}

return totalDuetime / totalCount;

}

public static long get95AvgTime(){

Arrays.sort(duetime);

return duetime[duetime.length/100*95];

}

public static boolean isCando() {

return cando;

}

public static void setCando(boolean cando) {

yace.cando = cando;

}

public static int getTotalCount() {

return totalCount;

}

public static void setTotalCount(int totalCount) {

yace.totalCount = totalCount;

duetime = new int[totalCount];

}

}