> 作者：燒雞太子爺
>
> 來源：[恆生LIGHT雲社群](https://developer.hs.net/thread/1613)

## 簡介

今年公司開發者大會是線上的形式，按照慣例，為了服務的保障，需要對整個系統的效能做一個評估，臨時抱佛腳，比較常用的工具有jmeter和Apache Bench，最終在兩者之間選擇了Apache Bench(簡稱ab)，也就針對ab工具做了一些總結。

## AB簡介

開啟官網可以看到下面一段話：

```
ab is a tool for benchmarking your Apache Hypertext Transfer Protocol (HTTP) server. It is designed to give you an impression

of how your current Apache installation performs. This especially shows you how many requests per second your Apache installation

is capable of serving.
```

ApacheBench 是 Apache 伺服器自帶的一個web壓力測試工具，簡稱ab。ab又是一個行工具，對發起負載的本機要求很低，根據ab 可以建立很多的併發訪問執行緒，模擬多個訪問者同時對某一URL地址進行訪問，因此可以用來測試目標伺服器的負載壓力。總的來說ab工具小巧簡單，上手學習較快，可以提供需要的基本效能指標，但是沒有圖形化結果，不能監控。

## jmeter和ab的比較

這個網上有很多的介紹，收集找了一位大神的總結（具體的不多說，大家可以自行百度）

1、jmeter是一次完整的請求和返回， 而AB只是發出去請求，並不對返回做處理，只是請求傳送成功或者失敗。 所以從準確性來說，Jmeter更準確，而AB速度更快，可以用最少的機器資源產生更多的訪問請求；

2、Jmeter本身支援斷言、可變引數和CSV資料集的輸入，能設定更加靈活多變的的測試場景，而AB則不支援（暫時沒想到）；

3、Jmeter可以提供更加詳細的統計結果資料，比如介面錯誤資訊、單執行緒的請求時間等，而AB則不支援；

4、Jmeter不支援精確時間的壓測，比如壓測10分鐘，但是AB支援；

5、Jmeter支援分散式的壓測叢集，且支援函式，AB不支援；

6、軟體自身耗費資源：Jmeter由於比較重，且統計了很多結果資料，比AB耗時耗費資源多，AB屬於超輕量級，在開發測試過程中十分適合做單介面壓測。

因為本次只針對單個介面做測試，手上剛好有空閒的linux機器，綜合考慮就選擇了AB，廢話不多說，下面就進行AB的使用做一些講解。

## AB的使用

官網針對ab的使用做了很詳細的介紹，我們可以去檢視官網地址：

https://httpd.apache.org/docs/2.4/programs/ab.html

下面做了一些節抄，英文比較簡單，就不做翻譯了。

### ab引數

```
ab [ -A auth-username:password ] [ -b windowsize ] [ -B local-address ] [ -c concurrency ] [ -C cookie-name=value ] [ -d ]

[ -e csv-file ] [ -E client-certificate file ] [ -f protocol ] [ -g gnuplot-file ] [ -h ] [ -H custom-header ] [ -i ] [ -k ]

[ -l ] [ -m HTTP-method ] [ -n requests ] [ -p POST-file ] [ -P proxy-auth-username:password ] [ -q ] [ -r ] [ -s timeout ]

[ -S ] [ -t timelimit ] [ -T content-type ] [ -u PUT-file ] [ -v verbosity] [ -V ] [ -w ] [ -x <table>-attributes ]

[ -X proxy[:port] ] [ -y <tr>-attributes ] [ -z <td>-attributes ] [ -Z ciphersuite ] [http[s]://]hostname[:port]/path
```

### 引數說明

- -A auth-username:password

```
Supply BASIC Authentication credentials to the server. The username and password are separated by a single : and sent on the wire base64 encoded. The string is sent regardless of whether the server needs it (i.e., has sent an 401 authentication needed).
```

- -b windowsize

```
Size of TCP send/receive buffer, in bytes.
```

- -B local-address

```
Address to bind to when making outgoing connections.
```

- -c concurrency

```
Number of multiple requests to perform at a time. Default is one request at a time.
```

- -C cookie-name=value

```
Add a Cookie: line to the request. The argument is typically in the form of a name=value pair. This field is repeatable.
```

- -d

```
Do not display the "percentage served within XX [ms] table". (legacy support).
```

- -e csv-file

```
Write a Comma separated value (CSV) file which contains for each percentage (from 1% to 100%) the time (in milliseconds) it took to serve that percentage of the requests. This is usually more useful than the 'gnuplot' file; as the results are already 'binned'.
```

- -E client-certificate-file

```
When connecting to an SSL website, use the provided client certificate in PEM format to authenticate with the server. The file is expected to contain the client certificate, followed by intermediate certificates, followed by the private key. Available in 2.4.36 and later.
```

- -f protocol

```
Specify SSL/TLS protocol (SSL2, SSL3, TLS1, TLS1.1, TLS1.2, or ALL). TLS1.1 and TLS1.2 support available in 2.4.4 and later.
```

- -g gnuplot-file

```
Write all measured values out as a 'gnuplot' or TSV (Tab separate values) file. This file can easily be imported into packages like Gnuplot, IDL, Mathematica, Igor or even Excel. The labels are on the first line of the file.
```

- -h

```
Display usage information.
```

- -H custom-header

```
Append extra headers to the request. The argument is typically in the form of a valid header line, containing a colon-separated field-value pair (i.e., "Accept-Encoding: zip/zop;8bit").
```

- -i

```
Do HEAD requests instead of GET.
```

- -k

```
Enable the HTTP KeepAlive feature, i.e., perform multiple requests within one HTTP session. Default is no KeepAlive.
```

- -l

```
Do not report errors if the length of the responses is not constant. This can be useful for dynamic pages. Available in 2.4.7 and later.
```

- -m HTTP-method

```
Custom HTTP method for the requests. Available in 2.4.10 and later.
```

- -n requests

```
Number of requests to perform for the benchmarking session. The default is to just perform a single request which usually leads to non-representative benchmarking results.
```

- -p POST-file

```
File containing data to POST. Remember to also set -T.
```

- -P proxy-auth-username:password

```
Supply BASIC Authentication credentials to a proxy en-route. The username and password are separated by a single : and sent on the wire base64 encoded. The string is sent regardless of whether the proxy needs it (i.e., has sent an 407 proxy authentication needed).
```

- -q

```
When processing more than 150 requests, ab outputs a progress count on stderr every 10% or 100 requests or so. The -q flag will suppress these messages.
```

- -r

```
Don't exit on socket receive errors.
```

- -s timeout

```
Maximum number of seconds to wait before the socket times out. Default is 30 seconds. Available in 2.4.4 and later.
```

- -S

```
Do not display the median and standard deviation values, nor display the warning/error messages when the average and median are more than one or two times the standard deviation apart. And default to the min/avg/max values. (legacy support).
```

- -t timelimit

```
Maximum number of seconds to spend for benchmarking. This implies a -n 50000 internally. Use this to benchmark the server within a fixed total amount of time. Per default there is no timelimit.
```

- -T content-type

```
Content-type header to use for POST/PUT data, eg. application/x-www-form-urlencoded. Default is text/plain.
```

- -u PUT-file

```
File containing data to PUT. Remember to also set -T.
```

- -v verbosity

```
Set verbosity level - 4 and above prints information on headers, 3 and above prints response codes (404, 200, etc.), 2 and above prints warnings and info.
```

- -V

```
Display version number and exit.
```

- -w

```
Print out results in HTML tables. Default table is two columns wide, with a white background.
```

- -x -attributes

```
String to use as attributes for table. Attributes are inserted table here.
```

- -X proxy[:port]

```
Use a proxy server for the requests.
```

- -y -attributes

```
String to use as attributes for tr.
```

- -z -attributes

```
String to use as attributes for tb
```

- -Z ciphersuite

```
Specify SSL/TLS cipher suite (See openssl ciphers)
```

### 引數說明

**Server Software**

The value, if any, returned in the server HTTP header of the first successful response. This includes all characters in the header from beginning to the point a character with decimal value of 32 (most notably: a space or CR/LF) is detected.

**Server Hostname**

The DNS or IP address given on the command line

**Server Port**

The port to which ab is connecting. If no port is given on the command line, this will default to 80 for http and 443 for https.

**SSL/TLS Protocol**

The protocol parameters negotiated between the client and server. This will only be printed if SSL is used.

**Document Path**

The request URI parsed from the command line string.

**Document Length**

This is the size in bytes of the first successfully returned document. If the document length changes during testing, the response is considered an error.

**Concurrency Level**

The number of concurrent clients used during the test

**Time taken for tests**

This is the time taken from the moment the first socket connection is created to the moment the last response is received

**Complete requests**

The number of successful responses received

**Failed requests**

The number of requests that were considered a failure. If the number is greater than zero, another line will be printed showing the number of requests that failed due to connecting, reading, incorrect content length, or exceptions.

**Write errors**

The number of errors that failed during write (broken pipe).

**Non-2xx responses**

The number of responses that were not in the 200 series of response codes. If all responses were 200, this field is not printed.

**Keep-Alive requests**

The number of connections that resulted in Keep-Alive requests

**Total body sent**

If configured to send data as part of the test, this is the total number of bytes sent during the tests. This field is omitted if the test did not include a body to send.

**Total transferred**

The total number of bytes received from the server. This number is essentially the number of bytes sent over the wire.

**HTML transferred**

The total number of document bytes received from the server. This number excludes bytes received in HTTP headers

**Requests per second**

This is the number of requests per second. This value is the result of dividing the number of requests by the total time taken

**Time per request**

The average time spent per request. The first value is calculated with the formula concurrency * timetaken * 1000 / done while the second value is calculated with the formula timetaken * 1000 / done

**Transfer rate**

The rate of transfer as calculated by the formula totalread / 1024 / timetaken

## 舉例

從上面可以看到ab支援的引數很多，但其實我們一般來說只有-n（傳送的請求總數）和 -c（請求的併發執行緒數）的引數是必要的。

![1.jpg](https://s4.51cto.com/images/blog/202111/29113212_61a449bc2c15267945.jpg?x-oss-process=image/watermark,size_14,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_100,g_se,x_10,y_10,shadow_20,type_ZmFuZ3poZW5naGVpdGk= "3838")

![2.jpg](https://s4.51cto.com/images/blog/202111/29113212_61a449bc2642877077.jpg?x-oss-process=image/watermark,size_14,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_100,g_se,x_10,y_10,shadow_20,type_ZmFuZ3poZW5naGVpdGk= "3839")

從圖上的列子我們可以看出，本次是啟動了200個執行緒併發，總共跑了2000次（為了避免洩露資訊保安，對介面做了隱私處理）。

結果我們觀察到

Requests for second為722.77,即每秒鐘處理722.77個請求；

Time per request為276.714,即請求的平均耗時為276.714ms；

另外還可以 99線，98線，95線等的耗時指標；

特別要注意，NON-2xx responses 為2000，而請求總共2000，則表示2000個請求返回的全部都是非2000，需要考慮請求返回是否都是錯誤的；
                        
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