ApacheBench

# ApacheBench
## 安装
```shell
[root@master ~]# yum -y install httpd-tools
```

## 使用
### 帮助说明
```shell
[root@master ~]# 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
    -l              Accept variable document length (use this for dynamic pages)
    -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.
    -m method       Method name
    -h              Display usage information (this message)
    -I              Disable TLS Server Name Indication (SNI) extension
    -Z ciphersuite  Specify SSL/TLS cipher suite (See openssl ciphers)
    -f protocol     Specify SSL/TLS protocol
                    (TLS1, TLS1.1, TLS1.2 or ALL)
    -E certfile     Specify optional client certificate chain and private key
```

### GET
- 修改Header中user-agent伪装浏览器请求
```shell
[root@master ~]# ab -n 100 -c 10 -H 'user-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.212 Safari/537.36 Edg/90.0.818.66' 'http://127.0.0.1/'
```

### POST
- post json格式数据
- Header中增加自定义user-agent
- post格式设置为application/json

```shell
[root@master ~]#  ab -n 100 -c 10 -p post.json -T 'application/json' -H 'user-agent: ApacheBench Zhangky'' 'http://127.0.0.1/login'

# json文件示例
[root@master ~]# cat post.json
{"user": "username", "pwd": "password"}
```

## 性能指标
### 1、吞吐率（Requests per second）

```shell
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。

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）

```shell
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）

```shell
要注意区分这个概念和并发连接数之间的区别，一个用户可能同时会产生多个会话，也即连接数。在HTTP/1.1下:
IE7支持两个并发连接
IE8支持6个并发连接
FireFox3支持4个并发连接

所以相应的，我们的并发用户数就得除以这个基数。
```

### 4、用户平均请求等待时间（Time per request）

```shell
计算公式：处理完成所有请求数所花费的时间/（总请求数/并发用户数），即：

Time per request=Time taken for tests/（Complete requests/Concurrency Level）
```

### 5、服务器平均请求等待时间（Time per request:across all concurrent requests）

```shell
计算公式：处理完成所有请求数所花费的时间/总请求数，即：
Time taken for/testsComplete requests

可以看到，它是吞吐率的倒数。
同时，它也等于用户平均请求等待时间/并发用户数，即:

Time per request/Concurrency Level
```