# 给 connect 的 static 模块加上url路径前缀 - fengmk2 # 给 connect 的 static 模块加上url路径前缀 估计我们使用 [connect](http://www.senchalabs.org/connect/) 都会很自然地按照官方的例子使用静态文件模块 [static](http://www.senchalabs.org/connect/static.html): ```js var connect = require("connect"); connect(connect.static(__dirname), function (req, res) { res.writeHead(200, { "Content-Type": "text/plain" }); res.end("Hello World\n"); }).listen(8124); console.log("Server running at http://127.0.0.1:8124/"); ``` ## 基准性能 为了评测 `static` 的性能，我们需要又一个基准对比。 ### 官方最纯洁的 helloworld 我们使用 nodejs 官方文档给出的 [helloworld](http://nodejs.org/docs/latest/api/synopsis.html) 做最基础的参照： ```js var http = require("http"); http .createServer(function (request, response) { response.writeHead(200, { "Content-Type": "text/plain" }); response.end("Hello World\n"); }) .listen(8124); console.log("Server running at http://127.0.0.1:8124/"); ``` ### 最纯洁的 connect helloworld 不使用任何中间件模块 ```js var connect = require("connect"); connect(function (req, res) { res.writeHead(200, { "Content-Type": "text/plain" }); res.end("Hello World\n"); }).listen(8124); console.log("Server running at http://127.0.0.1:8124/"); ``` ### 结合 [domain](http://nodejs.org/docs/latest/api/domain.html) 模块的 connect helloworld ```js var connect = require("connect"); var createDomain = require("domain").create; connect( function (req, res, next) { var domain = createDomain(); domain.on("error", function (err) { console.log("errrrrr", err); res.statusCode = 500; res.end(err.message + "\n"); domain.dispose(); }); domain.run(next); }, function (req, res, next) { if (req.url === "/error") { process.nextTick(function () { res.end("params: " + req.query.abc); }); return; } res.writeHead(200, { "Content-Type": "text/plain" }); res.end("Hello World\n"); }, ).listen(8124); console.log("Server running at http://127.0.0.1:8124/"); ``` ## 测试结果 官方最纯洁的 helloworld: `7851.56 qps` ``` $ siege -b -c10 -t10S http://127.0.0.1:8124/ ** SIEGE 2.72 ** Preparing 10 concurrent users for battle. The server is now under siege... Lifting the server siege... done. Transactions: 78123 hits Availability: 100.00 % Elapsed time: 9.95 secs Data transferred: 0.89 MB Response time: 0.00 secs Transaction rate: 7851.56 trans/sec Throughput: 0.09 MB/sec Concurrency: 9.93 Successful transactions: 78123 Failed transactions: 0 Longest transaction: 0.09 Shortest transaction: 0.00 ``` 最纯洁的 connect helloworld: `6808.19 qps` ``` $ siege -b -c10 -t10S http://127.0.0.1:8124/ ** SIEGE 2.72 ** Preparing 10 concurrent users for battle. The server is now under siege... Lifting the server siege... done. Transactions: 65699 hits Availability: 100.00 % Elapsed time: 9.65 secs Data transferred: 0.75 MB Response time: 0.00 secs Transaction rate: 6808.19 trans/sec Throughput: 0.08 MB/sec Concurrency: 9.96 Successful transactions: 65699 Failed transactions: 0 Longest transaction: 0.05 Shortest transaction: 0.00 ``` 使用 [domain](http://nodejs.org/docs/latest/api/domain.html) 模块的 connect helloworld: `5601.35 qps` [domain demo for express](https://speakerdeck.com/u/felixge/p/domains-in-node-08) ``` ** SIEGE 2.72 ** Preparing 50 concurrent users for battle. The server is now under siege... Lifting the server siege... done. Transactions: 53885 hits Availability: 100.00 % Elapsed time: 9.62 secs Data transferred: 0.62 MB Response time: 0.01 secs Transaction rate: 5601.35 trans/sec Throughput: 0.06 MB/sec Concurrency: 49.62 Successful transactions: 53885 Failed transactions: 0 Longest transaction: 0.05 Shortest transaction: 0.00 ``` 带 static 的 connect helloworld: `3636.98 qps` ``` $ siege -b -c10 -t10S http://127.0.0.1:8124/ ** SIEGE 2.72 ** Preparing 10 concurrent users for battle. The server is now under siege... Lifting the server siege... done. Transactions: 34915 hits Availability: 100.00 % Elapsed time: 9.60 secs Data transferred: 0.40 MB Response time: 0.00 secs Transaction rate: 3636.98 trans/sec Throughput: 0.04 MB/sec Concurrency: 9.97 Successful transactions: 34915 Failed transactions: 0 Longest transaction: 0.06 Shortest transaction: 0.00 ``` ## 为什么性能降低了50% 晕，为什么加上了 `static` 模块，性能会降低了`50％`这么多？ 查看 [static.send()](http://www.senchalabs.org/connect/static.html#send) 源代码: ```js // "hidden" file if (!hidden && '.' == basename(path)[0]) return next(); fs.stat(path, function(err, stat){ // mime type type = mime.lookup(path); // ignore ENOENT if (err) { if (fn) return fn(err); return ('ENOENT' == err.code || 'ENAMETOOLONG' == err.code) ? next() : next(err); // redirect directory in case index.html is present } else if (stat.isDirectory()) { if (!redirect) return next(); res.statusCode = 301; res.setHeader('Location', url.pathname + '/'); res.end('Redirecting to ' + url.pathname + '/'); return; } ``` static 模块每次都需要一次文件IO，判断文件是否存在，这是多么损耗性能啊。 ## 增加静态文件url路径前缀 既然找到性能问题所在，就可以解决此问题了。对症下药，无需让所有请求都经过 `static` 处理即可。 给 `static` 增加一个url前缀判断，例如 `/public/images/logo.jpg` 只有前缀是 `/public` 的 url 请求才需要进入 `static` 模块处理。 那么我们改进后的代码应该是这样的: ```js var connect = require("connect"); var app = connect(); app.use("/public", connect.static(__dirname)); app .use(function (req, res) { res.writeHead(200, { "Content-Type": "text/plain" }); res.end("Hello World\n"); }) .listen(8124); console.log("Server running at http://127.0.0.1:8124/"); ``` 性能如何？ wow `6749.03 qps`, 几乎和 connect hellowrold 一致。done! ```js $ siege -b -c10 -t10S http://127.0.0.1:8124/ ** SIEGE 2.72 ** Preparing 10 concurrent users for battle. The server is now under siege... Lifting the server siege... done. Transactions: 66073 hits Availability: 100.00 % Elapsed time: 9.79 secs Data transferred: 0.76 MB Response time: 0.00 secs Transaction rate: 6749.03 trans/sec Throughput: 0.08 MB/sec Concurrency: 9.97 Successful transactions: 66073 Failed transactions: 0 Longest transaction: 0.03 Shortest transaction: 0.00 ``` 重现一下之前的性能问题，访问 `/public/foo` 即可重现。 ```js $ siege -b -c10 -t10S http://127.0.0.1:8124/public/foo ** SIEGE 2.72 ** Preparing 10 concurrent users for battle. The server is now under siege... Lifting the server siege... done. Transactions: 37773 hits Availability: 100.00 % Elapsed time: 9.59 secs Data transferred: 0.43 MB Response time: 0.00 secs Transaction rate: 3938.79 trans/sec Throughput: 0.05 MB/sec Concurrency: 9.97 Successful transactions: 37773 Failed transactions: 0 Longest transaction: 0.05 Shortest transaction: 0.00 ``` ## 有爱 记得给 `connect.static` 加上一个url路径前缀喔! ^\_^ 希望本文对你有用.