原]HAproxy 代理技術原理探究

簡介

HAProxy是一款提供高可用性、負載均衡以及基於TCP（第四層）和HTTP（第七層）應用的代理軟件

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Features

1.免費
2.能夠做到4層以上代理
3.高性能
4.高穩定性

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使用案例

淘寶CDN(HTTP反向代理)

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測試:

HTTP代理 ab -i -c 500 -n 100000

       | --- node 8910 URL = /
HAproxy| --- node 8911 URL = /
       | --- node 8912 URL = /
       | --- node 8913 /test/ (reqisetbe ^[^\ ]*\ /(test|uri)/ server_uri_route) #按照規則轉發

####### haproxy :  (單獨由haproxy進行均衡負載)

Concurrency Level:      500
Time taken for tests:   32.562 seconds
Complete requests:      100000
Failed requests:        0
Write errors:           0
Total transferred:      36606588 bytes
HTML transferred:       0 bytes
Requests per second:    3071.02 [#/sec] (mean)
Time per request:       162.812 [ms] (mean)
Time per request:       0.326 [ms] (mean, across all concurrent requests)
Transfer rate:          1097.85 [Kbytes/sec] received

 

####### nginx : (單獨由nginx進行均衡負載)

Concurrency Level:      500
Time taken for tests:   36.539 seconds
Complete requests:      100000
Failed requests:        0
Write errors:           0
Total transferred:      38600000 bytes
HTML transferred:       0 bytes
Requests per second:    2736.82 [#/sec] (mean)
Time per request:       182.694 [ms] (mean)
Time per request:       0.365 [ms] (mean, across all concurrent requests)
Transfer rate:          1031.65 [Kbytes/sec] received

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對比Nginx

Name	Nginx	HAproxy
HTTP代理性能	9	10
TCP 代理性能	0	10
穩定性	10	10
轉發規則	10	7
HTTP代理性能	9	10
平滑升級	10	8

原理 epoll 轉發

驗證 轉發方式爲如下
通過TCP代理請求 www.baidu.com

client                   HAProxy                     Backend
curl |----------------->| 
                         accept(client)
                         recvfrom(client)
                         sendto(Backent)   
                                          |-------->|
                                                     dowith(HAProxy)
                                          |<--------|
                         recvfrom(Backend)
                         sendto(Client)
     |<-----------------|

strace 查看系統調用

    zhangbo3@vm-222:/etc/haproxy$ sudo strace -p 7876
    
    epoll_wait(0, {{EPOLLIN, {u32=5, u64=5}}}, 7, 1000) = 1
    *** (事件循環，監聽連接事件)
    
    accept(5, {
        sa_family=AF_INET, 
        sin_port=htons(56479), 
        sin_addr=inet_addr("127.0.0.1")
    }, [16]) = 1
    *** (來自客戶端[127.0.0.1]的請求, 端口56479[隨機端口])
    
    fcntl(1, F_SETFL, O_RDONLY|O_NONBLOCK)  = 0
    *** (設置連接socket爲非阻塞)
    
    setsockopt(1, SOL_TCP, TCP_NODELAY, [1], 4) = 0
    *** (設置TCP連接爲 NODELAY, 禁止Nagle算法)
    
    accept(5, 0x7fff8da2d7a0, [128]) = -1 EAGAIN 
    (Resource temporarily unavailable)
    *** (再次去accept連接失敗，因爲accept被循環包裹，需要返回 EAGAIN才break)
    
    recvfrom(1, "GET HTTP://www.baidu.com HTTP/1."..., 8192) = 212
    *** (收到來自客戶端的請求 curl -x 127.0.0.1:1180 www.baidu.com)
    
    recvfrom(1, 0x2560ac4, 7980, 0, 0, 0)   = -1 EAGAIN 
    (Resource temporarily unavailable)
    *** (返回EAGAIN後break,表示收到完整的TCP數據, 開始處理請求數據)
    
    epoll_ctl(0, EPOLL_CTL_ADD, 1, {EPOLLIN, {u32=1, u64=1}}) = 0
    *** (將來自客戶端的socket加入epoll監聽隊列)
    
    socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 2
    fcntl(2, F_SETFL, O_RDONLY|O_NONBLOCK)  = 0
    setsockopt(2, SOL_TCP, TCP_NODELAY, [1], 4) = 0
    connect(2, {
        sa_family=AF_INET, 
        sin_port=htons(8912), 
        sin_addr=inet_addr("127.0.0.1")
    }, 16) = -1 EINPROGRESS (Operation now in progress)
    *** (創建到backend的socket連接,這裏backend配置爲8912)
    *** (server server3 127.0.0.1:8912)
    
    sendto(2, "GET HTTP://www.baidu.com HTTP/1."..., 
    212, MSG_DONTWAIT|MSG_NOSIGNAL, NULL, 0) = 212
    *** (發送數據到backend)
    epoll_wait(0, {}, 7, 0)                 = 0
    *** (繼續進入epoll_wait,等待來自backend的數據返回)
    
    gettimeofday({1413020002, 322710}, NULL) = 0
    recvfrom(2, 0x255c960, 16384, 0, 0, 0)  = -1 EAGAIN 
    (Resource temporarily unavailable)
    *** (Backend數據來了)
    
    epoll_ctl(0, EPOLL_CTL_ADD, 2, {EPOLLIN, {u32=2, u64=2}}) = 0
    epoll_wait(0, {{EPOLLIN, {u32=2, u64=2}}}, 7, 1000) = 1
    gettimeofday({1413020003, 308930}, NULL) = 0
    
    recvfrom(2, "HTTP/1.1 200 OK\r\nDate: Sat, 11 O"...,16384) = 2896
    *** (backend 返回 HTTP 200, 這是標準HTTP協議頭)
    
    recvfrom(2, 0x255d4b0, 13488, 0, 0, 0)  = -1 EAGAIN 
    (Resource temporarily unavailable)
    
    sendto(1, "HTTP/1.1 200 OK\r\nDate: Sat, 11 O"...) = 2896
    *** (將backend返回的數據發送到front end)
    
    epoll_wait(0, {{EPOLLIN, {u32=2, u64=2}}}, 7, 1000) = 1
    *** (繼續進入epoll_wait)
    gettimeofday({1413020003, 309695}, NULL) = 0
    *** (客戶端連接超時，關閉連接)
    shutdown(2, 1 /* send */)               = 0
    close(2)                                = 0
    shutdown(1, 1 /* send */)               = 0
    close(1)                                = 0

驗證單進程模型 -> 查看線程數
cat /proc/7878/status

    Name:   haproxy
    State:  S (sleeping)
    ...
    Threads:        1
    SigQ:   0/15594
    SigPnd: 0000000000000000
    ShdPnd: 0000000000000000
    ...