ab – ApacheBench

只要是在架站之後,想要了解一下你的 http service (Apache) 的效能,這時候可以使用 Apache 內建的效能測試程式 – ab (Apache HTTP Server Benchmarking Tool) 來得知.

Ubuntu
直接透過 apt-get 安裝就可以了.

root@benjr:~# apt-get install apache2-utils

RedHat
比較複雜一點.要安裝幾個套件後才能使用.

[root@benjr Packages]# rpm -ivh httpd-tools-2.4.6-31.el7.x86_64.rpm
warning: httpd-tools-2.4.6-31.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID fd431d51: NOKEY
error: Failed dependencies:
        libapr-1.so.0()(64bit) is needed by httpd-tools-2.4.6-31.el7.x86_64
        libaprutil-1.so.0()(64bit) is needed by httpd-tools-2.4.6-31.el7.x86_64

[root@benjr Packages]# rpm -ivh apr-1.4.8-3.el7.x86_64.rpm
warning: apr-1.4.8-3.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID fd431d51: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...
   1:apr-1.4.8-3.el7                  ################################# [100%]
[root@benjr Packages]# rpm -ivh apr-util-1.5.2-6.el7.x86_64.rpm
warning: apr-util-1.5.2-6.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID fd431d51: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...
   1:apr-util-1.5.2-6.el7             ################################# [100%]
[root@benjr Packages]# rpm -ivh httpd-tools-2.4.6-31.el7.x86_64.rpm
warning: httpd-tools-2.4.6-31.el7.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID fd431d51: NOKEY
Preparing...                          ################################# [100%]
Updating / installing...
   1:httpd-tools-2.4.6-31.el7         ################################# [100%]

ab (ApacheBench) 工具存放在 httpd-tools 套件裡面,但安裝的時候會說少 libapr libaprutil 這兩個套件,但其實是要安裝 apr 與 apr-util 套件(在 RedHat Package 光碟內都有)

使用也相當簡單,就一行指令.

[root@benjr ]# ab -n 100 -c 10 http://www.google.com/index
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.google.com (be patient).....done


Server Software:        sffe
Server Hostname:        www.google.com
Server Port:            80

Document Path:          /index
Document Length:        1566 bytes

Concurrency Level:      10
Time taken for tests:   0.908 seconds
Complete requests:      100
Failed requests:        0
Write errors:           0
Non-2xx responses:      100
Total transferred:      177100 bytes
HTML transferred:       156600 bytes
Requests per second:    110.17 [#/sec] (mean)
Time per request:       90.769 [ms] (mean)
Time per request:       9.077 [ms] (mean, across all concurrent requests)
Transfer rate:          190.54 [Kbytes/sec] received

Connection Times (ms)
              min  mean[+/-sd] median   max
Connect:       22   39   6.3     39      61
Processing:    31   47   8.4     47      69
Waiting:       30   47   8.1     46      69
Total:         61   87  11.6     86     116

Percentage of the requests served within a certain time (ms)
  50%     86
  66%     91
  75%     92
  80%     96
  90%    101
  95%    110
  98%    114
  99%    116
 100%    116 (longest request)

指令 ab -n 100 -c 10 http://www.google.com/index
裡面用到兩個常用的參數
-n requests
Number of requests to perform (代表連續測試 x 次)
-c concurrency
Number of multiple requests to make at a time (代表同時有 x 個連線)
最後就是要測試的網址.

其他參數請參考官方文件 http://httpd.apache.org/docs/2.2/programs/ab.html

我們來看一下執行的結果
Concurrency Level: 10
代表同時有 10 個連線

Time taken for tests: 0.908 seconds

Complete requests: 100
完成的請求數.

Failed requests: 0
失敗的請求數.

Write errors: 0
Non-2xx responses: 100

Total transferred: 177100 bytes
總資料傳送 Bytes

HTML transferred: 156600 bytes
HTML 資料傳送 Bytes

Requests per second: 110.17 [#/sec] (mean)
平均每秒可以回應多少個請求.

Time per request: 90.769 [ms] (mean)
平均每次請求所花費的時間,

Time per request: 9.077 [ms] (mean, across all concurrent requests)
平均每個請求所花費的時間 (同時有 10 個連線)

Transfer rate: 190.54 [Kbytes/sec] received

首先要來了解什麼是 TCP 三方交握 (TCP 3-way handshake) ,所謂的 TCP 三方交握(TCP 3-way handshake) 就是 Server 與 Client 間透過 3 次的溝通,才會進行資料的傳輸
這步驟如下:

1. Client 用戶端向 Server 伺服器發送一個 "SYN" 訊息,跟 Server 伺服器請求連線.
2. 如果 Server 伺服器準備好與 Client 用戶端連線,就會回傳一個 "SYN-ACK" 的訊息.
3. 如果 Client 用戶端接受到剛剛的 "SYN-ACL" 而且也準備好,就會向 Server 伺服器發送一個 "ACK"訊號,讓 Server 伺服器知道現在要開始傳送資料了.

Client 用戶端每送一筆資料 Server 伺服器收到資料都會回傳給 Client 用戶端一個 ACK 訊號.但這樣未免太沒效率,所以通常會一次傳送多筆資料過去,這就是 TCP Sliding Window

Connection Times (ms)
min mean[+/-sd] median max
Connect: 22 39 6.3 39 61
Processing: 31 47 8.4 47 69
Waiting: 30 47 8.1 46 69
Total: 61 87 11.6 86 116

Connect:
這個就是剛剛說明 TCP 三方交握 (TCP 3-way handshake) 所需的時間.
Processing:
TCP 連線建立後,HTTP server 的資料全部都收到所花費的時間.
Waiting:
Client 發送到 HTTP 第一個 Byte 到全部完成所等待的時間.
Total:
Connect + Processing(包含 Waiting)