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PO“Proxying” a lot of HTTP requests with Node.js + Express 2
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copied!<p>I'm writing proxy in Node.js + Express 2. Proxy should:</p> <ol> <li>decrypt POST payload and issue HTTP request to server based on result;</li> <li>encrypt reply from server and send it back to client.</li> </ol> <p>Encryption-related part works fine. The problem I'm facing is timeouts. Proxy should process requests in less than 15 secs. And most of them are under 500ms, actually.</p> <p>Problem appears when I increase number of parallel requests. Most requests are completed ok, but some are failed after 15 secs + couple of millis. <code>ab -n5000 -c300</code> works fine, but with concurrency of 500 it fails for some requests with timeout.</p> <p>I could only speculate, but it seems thant problem is an order of callbacks exectuion. Is it possible that requests that comes first are hanging until <code>ETIMEDOUT</code> because of node's focus in latest ones which are still being processed in time under 500ms.</p> <p>P.S.: There is no problem with remote server. I'm using <a href="https://github.com/mikeal/request" rel="noreferrer">request</a> for interactions with it.</p> <p><strong>upd</strong></p> <p>The way things works with some code:</p> <pre class="lang-js prettyprint-override"><code>function queryRemote(req, res) { var options = {}; // built based on req object (URI, body, authorization, etc.) request(options, function(err, httpResponse, body) { return err ? send500(req, res) : res.end(encrypt(body)); }); } app.use(myBodyParser); // reads hex string in payload // and calls next() on 'end' event app.post('/', [checkHeaders, // check Content-Type and Authorization headers authUser, // query DB and call next() parseRequest], // decrypt payload, parse JSON, call next() function(req, res) { req.socket.setTimeout(TIMEOUT); queryRemote(req, res); }); </code></pre> <p>My problem is following: when <code>ab</code> issuing, let's say, 20 POSTs to <code>/</code>, express route handler gets called like thousands of times. That's not always happening, sometimes 20 and only 20 requests are processed in timely fashion.</p> <p>Of course, <code>ab</code> is not a problem. I'm 100% sure that only 20 requests sent by <code>ab</code>. But route handler gets called multiple times.</p> <p>I can't find reasons for such behaviour, any advice?</p>

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