Linux命令之ab压力测试

朱雀 2023-05-30 04:53 210阅读 0赞

ab是apache自带的压力测试工具。ab非常实用，它不仅可以对apache服务器进行网站访问压力测试，也可以对或其它类型的服务器进行压力测试

ab的原理：ab命令会创建多个并发访问线程，模拟多个访问者同时对某一URL地址进行访问。

ab命令对发出负载的计算机要求很低，不会占用很高CPU和内存，但也能给目标服务器产生巨大的负载，使用的时候要注意，如果一次太多的负载，可能导致主机资源耗尽，严重时可能死机。

1.安装  
注意：如果不想安装apache但是又想使用ab命令的话，我们可以直接安装apache的工具包httpd-tools。如下：

yum -y install httpd-tools

2.使用  
使用时注意一点，找到ab的位置在执行

[root@server bin]# which ab
    /usr/bin/ab
    [root@server bin]# ab -V
    This is ApacheBench, Version 2.3 <$Revision: 1430300 $>
    Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
    Licensed to The Apache Software Foundation, http://www.apache.org/

[root@localhost ~]# ab --help
    ab: wrong number of arguments
    Usage: ab [options] [http[s]://]hostname[:port]/path
    Options are:
        -n requests     Number of requests to perform
        -c concurrency  Number of multiple requests to make at a time
        -t timelimit    Seconds to max. to spend on benchmarking
                        This implies -n 50000
        -s timeout      Seconds to max. wait for each response
                        Default is 30 seconds
        -b windowsize   Size of TCP send/receive buffer, in bytes
        -B address      Address to bind to when making outgoing connections
        -p postfile     File containing data to POST. Remember also to set -T
        -u putfile      File containing data to PUT. Remember also to set -T
        -T content-type Content-type header to use for POST/PUT data, eg.
                        'application/x-www-form-urlencoded'
                        Default is 'text/plain'
        -v verbosity    How much troubleshooting info to print
        -w              Print out results in HTML tables
        -i              Use HEAD instead of GET
        -x attributes   String to insert as table attributes
        -y attributes   String to insert as tr attributes
        -z attributes   String to insert as td or th attributes
        -C attribute    Add cookie, eg. 'Apache=1234'. (repeatable)
        -H attribute    Add Arbitrary header line, eg. 'Accept-Encoding: gzip'
                        Inserted after all normal header lines. (repeatable)
        -A attribute    Add Basic WWW Authentication, the attributes
                        are a colon separated username and password.
        -P attribute    Add Basic Proxy Authentication, the attributes
                        are a colon separated username and password.
        -X proxy:port   Proxyserver and port number to use
        -V              Print version number and exit
        -k              Use HTTP KeepAlive feature
        -d              Do not show percentiles served table.
        -S              Do not show confidence estimators and warnings.
        -q              Do not show progress when doing more than 150 requests
        -g filename     Output collected data to gnuplot format file.
        -e filename     Output CSV file with percentages served
        -r              Don't exit on socket receive errors.
        -h              Display usage information (this message)
        -Z ciphersuite  Specify SSL/TLS cipher suite (See openssl ciphers)
        -f protocol     Specify SSL/TLS protocol
                        (SSL3, TLS1, TLS1.1, TLS1.2 or ALL)

ab命令最基本的参数是-n和-c：

\-n 执行的请求数量  
\-c 并发请求个数

压测过程如下：

[root@localhost bin]# ab -n10 -c3 https://www.baidu.com/
     This is ApacheBench, Version 2.3 <$Revision: 1430300 $>
     Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
     Licensed to The Apache Software Foundation, http://www.apache.org/
     Benchmarking www.baidu.com (be patient).....done
      Server Software:        BWS/1.1         #服务器软件
      Server Hostname:        www.baidu.com   #域名
    Server Port:            443             #请求端口号
    SSL/TLS Protocol:       TLSv1.2,ECDHE-RSA-AES128-GCM-SHA256,2048,128
    Document Path:          /                #文件路径
    Document Length:        227 bytes        #页面字节数
    Concurrency Level:      3                #请求的并发数
    Time taken for tests:   0.091 seconds    #总访问时间
    Complete requests:      10               #请求成功数量
    Failed requests:        0                #请求失败数量
    Write errors:           0                
    Total transferred:      8930 bytes       #请求总数据大小（包括header头信息）
    HTML transferred:       2270 bytes       #html页面实际总字节数
    Requests per second:    109.89 [#/sec] (mean)  #每秒多少请求，这个是非常重要的参数数值，服务器的吞吐量
    Time per request:       27.299 [ms] (mean)        #用户平均请求等待时间
    Time per request:       9.100 [ms] (mean, across all concurrent requests) #服务器平均处理时间，也就是服务器吞吐量的倒数
    Transfer rate:          95.84 [Kbytes/sec] received     #每秒获取的数据长度
    Connection Times (ms)
                  min  mean[+/-sd] median   max
    Connect:       14   16   1.2     16      17
    Processing:     5    6   0.4      6       6
    Waiting:        5    6   0.4      6       6
    Total:         19   22   1.5     22      24
    Percentage of the requests served within a certain time (ms)
      50%     22   #50%用户请求在22ms内返回
      66%     23
      75%     23
      80%     23
      90%     24
      95%     24
      98%     24
      99%     24   #%99用户请求在24ms内返回
     100%     24 (longest request)

ab性能指标  
在进行性能测试过程中有几个指标比较重要：

1、吞吐率（Requests per second）

服务器并发处理能力的量化描述，单位是reqs/s，指的是在某个并发用户数下单位时间内处理的请求数。某个并发用户数下单位时间内能处理的最大请求数，称之为最大吞吐率。

记住：吞吐率是基于并发用户数的。这句话代表了两个含义：

a、吞吐率和并发用户数相关

b、不同的并发用户数下，吞吐率一般是不同的

计算公式：总请求数/处理完成这些请求数所花费的时间，即

Request per second=Complete requests/Time taken for tests

必须要说明的是，这个数值表示当前机器的整体性能，值越大越好。

2、并发连接数（The number of concurrent connections）

并发连接数指的是某个时刻服务器所接受的请求数目，简单的讲，就是一个会话。

3、并发用户数（Concurrency Level）