摘要：一個小小的需求，可能會遇到很多問題，但是搜索相關(guān)的關(guān)鍵字，就能快速實現(xiàn)出來，完成一個小目標，事半功倍。下面開始一個小需求一個地址有兩套頁面，需要在后端根據(jù)瀏覽器的來顯示不同的頁面。而的結(jié)果在個并發(fā)的時候，失敗的請求數(shù)依舊是。

之前做一次分享 如何快速學(xué)習(xí)一門新的語言的直播分享 但是那是以實現(xiàn)一個后端框架的角度來講的，道理想通，我們要以實際的需求出發(fā)。一個小小的需求，可能會遇到很多問題，但是搜索相關(guān)的關(guān)鍵字，就能快速實現(xiàn)出來，完成一個小目標，事半功倍。
死記硬背手冊，太枯燥了，反正我是看不下去，不如直接來個小項目。下面開始：

pc、mobile 一個地址有兩套頁面，需要在后端根據(jù)瀏覽器的 user_agent 來顯示不同的頁面。
通過 php 來做，當然可以，但是活動頁面訪問量一般都比較大，想優(yōu)化些，所以想嘗試下 lua。

可以直接上 openresty，不過有時候就是想折騰。
安裝的步驟 https://mengkang.net/994.html （如果你想實踐的話再看吧）

-- 判斷是否是手機瀏覽器
function isMobile(userAgent)
    -- 99% 前三個都能匹配上吧
    local mobile = {
        "phone", "android", "mobile", "itouch", "ipod", "symbian", "htc", "palmos", "blackberry", "opera mini", "windows ce", "nokia", "fennec",
        "hiptop", "kindle", "mot", "webos", "samsung", "sonyericsson", "wap", "avantgo", "eudoraweb", "minimo", "netfront", "teleca"
    }
    userAgent = string.lower(userAgent)

    for i, v in ipairs(mobile) do
        if string.match(userAgent, v) then
            return true
        end
    end

    return false
end

-- 根據(jù)id + 瀏覽器類型展示活動頁面
function showPromotionHtml(id, isMobile)
    local path = "/data/www/mengkang/demo/promotion/"
    local filename

    if isMobile then
        path = path .. "mobile"
    else
        path = path .. "pc"
    end

    filename = path .. "/" .. id .. ".html"

    if file_exists(filename) then
        local file = io.open(filename,"r")
        io.input(file)
        print(io.read("*a"))
        io.close(file)
    else
        print("文件不存在: " .. string.gsub(filename, "/data/www/mengkang/demo", ""))
    end
end

-- 判斷文件是否存在
function file_exists(path)
    local file = io.open(path, "rb")
    if file then file:close() end
    return file ~= nil
end

local id = 1
local userAgent = "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/61.0.3163.79 Safari/537.36"
showPromotionHtml(id, isMobile(userAgent))

作為一個 lua 菜鳥，通過這個小需求我查了哪些資料

變量的定義
函數(shù)的寫法
循環(huán)的了解
判斷邏輯的寫法
注釋的寫法
文件 i/o
字符串拼接 ..
字符串查找 string.match
字符串轉(zhuǎn)小寫 string.lower

-- 判斷是否是手機瀏覽器
function isMobile(userAgent)
    -- 99% 前三個都能匹配上吧
    local mobile = {
        "phone", "android", "mobile", "itouch", "ipod", "symbian", "htc", "palmos", "blackberry", "opera mini", "windows ce", "nokia", "fennec",
        "hiptop", "kindle", "mot", "webos", "samsung", "sonyericsson", "wap", "avantgo", "eudoraweb", "minimo", "netfront", "teleca"
    }
    userAgent = string.lower(userAgent)

    for i, v in ipairs(mobile) do
        if string.match(userAgent, v) then
            return true
        end
    end

    return false
end

-- 根據(jù)id + 瀏覽器類型展示活動頁面
function showPromotionHtml(id, isMobile)
    local path = "/data/www/mengkang/demo/promotion/"
    local filename

    if isMobile then
        path = path .. "mobile"
    else
        path = path .. "pc"
    end

    filename = path .. "/" .. id .. ".html"

    if file_exists(filename) then
        local file = io.open(filename,"r")
        io.input(file)
        ngx.say(io.read("*a"))
        io.close(file)
    else
        ngx.say("file not found : " .. string.gsub(filename, "/data/www/mengkang/demo", ""))
    end
end

-- 判斷文件是否存在
function file_exists(path)
    local file = io.open(path, "rb")
    if file then file:close() end
    return file ~= nil
end

local id = ngx.var.id
local userAgent = ngx.req.get_headers().user_agent
showPromotionHtml(id, isMobile(userAgent))

server
{
    listen       80;
    server_name mengkang.net

    location ~ /promotion/(d+)
    {
        set $id $1;
        default_type "text/html";
        content_by_lua_file /data/www/lua/1.lua;
    }
}

https://mengkang.net/promotion/1
https://mengkang.net/promotio...
切換 user_agent 即可看到，不同的 pc 和 mobile 兩個版本的頁面

rewrite ^/promotion2/(.*)$  /demo/promotion.php last;

也就是說訪問 http://mengkang.net/promotion/1 和 http://mengkang.net/promotion2/1 是一樣的結(jié)果
配置說明
雙核4G   
nginx 配置一致  
php 版本：7.0.11
php-fpm 配置：
pm = dynamic
pm.max_children = 10
pm.start_servers = 4
pm.min_spare_servers = 4
pm.max_spare_servers = 10
php 壓測結(jié)果
ab -n 1000 -c 100 http://mengkang.net/promotion2/1
Requests per second:    3105.21 [#/sec] (mean)
Time per request:       32.204 [ms] (mean)

ab -n 4000 -c 400 http://mengkang.net/promotion2/1
Requests per second:    3361.87 [#/sec] (mean)
Time per request:       118.981 [ms] (mean)
Complete requests:      4000
Failed requests:        259

ab -n 8000 -c 800 http://mengkang.net/promotion2/1
Requests per second:    3358.20 [#/sec] (mean)
Time per request:       238.223 [ms] (mean)
Complete requests:      8000
Failed requests:        654

ab -n 10000 -c 1000 http://mengkang.net/promotion2/1
Requests per second:    3275.30 [#/sec] (mean)
Time per request:       305.315 [ms] (mean)
Complete requests:      10000
Failed requests:        9150
lua 壓測結(jié)果
ab -n 1000 -c 100 http://mengkang.net/promotion/1
Requests per second:    6014.89 [#/sec] (mean)
Time per request:       16.625 [ms] (mean)

ab -n 4000 -c 400 http://mengkang.net/promotion/1
Complete requests:      4000
Failed requests:        0
Requests per second:    6190.57 [#/sec] (mean)
Time per request:       64.614 [ms] (mean)

ab -n 8000 -c 800 http://mengkang.net/promotion/1
Complete requests:      8000
Failed requests:        0
Requests per second:    7046.66 [#/sec] (mean)
Time per request:       113.529 [ms] (mean

ab -n 10000 -c 1000 http://mengkang.net/promotion/1
Complete requests:      10000
Failed requests:        0
Requests per second:    5670.38 [#/sec] (mean)
Time per request:       176.355 [ms] (mean)
對比可見
PHP qps 在 3000左右，nginx_lua qps 在 7000 左右。qps 提升了1倍多，而且響應(yīng)時間更短，而且 php 在 400 個并發(fā)的時候開始出現(xiàn)比較多的失敗請求，吞吐率開始下降。而 lua 的結(jié)果在 1000 個并發(fā)的時候，失敗的請求數(shù)依舊是0。