原文链接：http://buyingfei.com/2018/05/24/abtool/
ab(Apache benchmark)是一款常用的压力测试工具。
安装
sudo yum install httpd-tools
命令参数
$ ab -h
Usage: ab [options] [http[s]://]hostname[:port]/path
Options are:
-n requests Number of requests to perform
-c concurrency [并发数 常用] Number of multiple requests to make
-t timelimit [持续请求时间 常用]Seconds to max. wait for responses
-b windowsize Size of TCP send/receive buffer, in bytes
-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 for POSTing, 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.
-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 (SSL2, SSL3, TLS1, or ALL)
本次测试以是否发生错误为准[nginx 报错以及ab 返回结果是否有错误]，测试环境为本地虚拟机centos 系统
测试接口(以get 方式) http://tickets.2345.com:12345/tickets/m/help/getRootCategory?product=1&type=0
** 1 先并发200 同时请求**
$ ab -t 10 -c 200 'http://tickets.2345.com:12345/tickets/m/help/getRootCategory?product=1&type=0'
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking tickets.2345.com (be patient)
Completed 5000 requests
Completed 10000 requests
Completed 15000 requests
Completed 20000 requests
Completed 25000 requests
Completed 30000 requests
Finished 34664 requests
Server Software: nginx [web服务器软件及版本]
Server Hostname: tickets.2345.com [表示请求的URL中的主机部分名称]
Server Port: 12345 [被测试的Web服务器的监听端口]
Document Path: /tickets/m/help/getRootCategory?product=1&type=0 [ 请求的页面路径]
Document Length: 298 bytes [页面大小]
Concurrency Level: 200 [并发数]
Time taken for tests: 10.000 seconds [测试总共花费的时间]
Complete requests: 34664 [完成的请求数]
Failed requests: 34136 [失败的请求数，这里的失败是指请求的连接服务器、发送数据、接收数据等环节发生异常，以及无响应后超时的情况。对于超时时间的设置可以用ab的-t参数。如果接受到的http响应数据的头信息中含有2xx以外的状态码，则会在测试结果显示另一个名为“Non-2xx responses”的统计项，用于统计这部分请求数，这些请求并不算是失败的请求。
只要出现Failed requests就会多一行数据来统计失败的原因，分别有Connect、Length、Exceptions。
Connect 无法送出要求、目标主机连接失败、要求的过程中被中断。
Length 响应的内容长度不一致 ( 以 Content-Length 头值为判断依据 )。
Exception 发生无法预期的错误。]
(Connect: 0, Receive: 0, Length: 34136, Exceptions: 0)
Write errors: 0 [ 写入错误]
Non-2xx responses: 34136
Total transferred: 11432992 bytes [总共传输字节数，包含http的头信息等。使用ab的-v参数即可查看详细的http头信息。]
HTML transferred: 5823920 bytes [html字节数，实际的页面传递字节数。也就是减去了Total transferred中http响应数据中头信息的长度。]
Requests per second: 3466.37 [#/sec] (mean) [每秒处理的请求数，服务器的吞吐量]
Time per request: 57.697 [ms] (mean) [用户平均请求等待时间]
Time per request: 0.288 [ms] (mean, across all concurrent requests) [服务器平均处理时间]
Transfer rate: 1116.49 [Kbytes/sec] received [平均传输速率（每秒收到的速率）。可以很好的说明服务器在处理能力达到限制时，其出口带宽的需求量。]
Connection Times (ms) [压力测试时的连接处理时间。]
min mean[+/-sd] median max
Connect: 0 0 1.2 0 17
Processing: 7 53 276.4 20 2617
Waiting: 7 53 276.4 20 2617
Total: 9 53 276.7 20 2617
Percentage of the requests served within a certain time (ms)
50% 20
66% 21
75% 22
80% 23
90% 24
95% 27
98% 34
99% 2443
100% 2617 (longest request)
结果分析： 当并发数为200 时，34664 个请求，34136 个错误，放弃这次结果
** 2 并发120 同时请求**
$ ab -t 10 -c 120 'http://tickets.2345.com:12345/tickets/m/help/getRootCategory?product=1&type=0'
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking tickets.2345.com (be patient)
Finished 903 requests
Server Software: nginx
Server Hostname: tickets.2345.com
Server Port: 12345
Document Path: /tickets/m/help/getRootCategory?product=1&type=0
Document Length: 298 bytes
Concurrency Level: 120
Time taken for tests: 10.010 seconds
Complete requests: 903
Failed requests: 0
Write errors: 0
Total transferred: 521031 bytes
HTML transferred: 269094 bytes
Requests per second: 90.21 [#/sec] (mean)
Time per request: 1330.250 [ms] (mean)
Time per request: 11.085 [ms] (mean, across all concurrent requests)
Transfer rate: 50.83 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 2 4.6 0 15
Processing: 28 1243 307.5 1283 1678
Waiting: 17 1243 307.6 1283 1678
Total: 29 1245 303.8 1284 1678
Percentage of the requests served within a certain time (ms)
50% 1283
66% 1306
75% 1319
80% 1335
90% 1645
95% 1660
98% 1669
99% 1671
100% 1678 (longest request)
结果分析： 当并发数为120 时，903 个请求，0 个错误，这次结果待考证，是否能承载更大负载
3 并发130 同时请求
$ ab -t 10 -c 130 'http://tickets.2345.com:12345/tickets/m/help/getRootCategory?product=1&type=0'
This is ApacheBench, Version 2.3 <$Revision: 655654 $>
Copyright 1996 Adam Twiss, Zeus Technology Ltd, http://www.zeustech.net/
Licensed to The Apache Software Foundation, http://www.apache.org/
Benchmarking tickets.2345.com (be patient)
Finished 1063 requests
Server Software: nginx
Server Hostname: tickets.2345.com
Server Port: 12345
Document Path: /tickets/m/help/getRootCategory?product=1&type=0
Document Length: 298 bytes
Concurrency Level: 130
Time taken for tests: 10.007 seconds
Complete requests: 1063
Failed requests: 149
(Connect: 0, Receive: 0, Length: 149, Exceptions: 0)
Write errors: 0
Non-2xx responses: 149
Total transferred: 575952 bytes
HTML transferred: 297106 bytes
Requests per second: 106.22 [#/sec] (mean)
Time per request: 1223.859 [ms] (mean)
Time per request: 9.414 [ms] (mean, across all concurrent requests)
Transfer rate: 56.20 [Kbytes/sec] received
Connection Times (ms)
min mean[+/-sd] median max
Connect: 0 1 3.2 0 10
Processing: 0 1133 538.7 1398 1557
Waiting: 0 1133 538.8 1398 1557
Total: 0 1134 537.9 1398 1557
Percentage of the requests served within a certain time (ms)
50% 1398
66% 1416
75% 1423
80% 1429
90% 1535
95% 1543
98% 1549
99% 1552
100% 1557 (longest request)
结果分析： 当并发数为130 时，1063 个请求，149 个错误，这次结果待考证，此时请求QPS 在90~100 之间
这是否达到系统极限那？ 通过sar -q、sar -u、sar -r 分析 系统cpu 占用还不到50%，IO 没有等待时长、内存也在系统承受范围之内，此时需要调整nginx 、php-fpm 等相关配置，来充分发挥系统性能。
