A benchmark script for measuring client latency

benchmark/client_latency.js

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+// first start node http_simple.js
+var http = require('http');
+
+var latency = [];
+
+var numRequests = parseInt(process.argv[2], 10) || 100;
+var maxSockets = parseInt(process.argv[3], 10) || 100;
+var runs = parseInt(process.argv[4], 10) || 100;
+var prefix = process.argv[5] || '';
+if (prefix) prefix += '_';
+var request = require('request');
+var r = 0;
+
+var port = parseInt(process.env.PORT, 10) || 8000;
+var host = process.env.HOST || '127.0.0.1';
+
+http.globalAgent.maxSockets = maxSockets;
+
+run();
+
+function run() {
+  if (r++ === runs) {
+    return finish();
+  }
+
+  // make numRequests in parallel
+  // retain the order in which they are *made*.  This requires trapping
+  // each one in a closure, since otherwise, we'll of course end
+  // up mostly sorting them in ascending order, since the cb from a
+  // fast request will almost always be called before the cb from a
+  // slow one.
+  var c = numRequests;
+  var lat = [];
+  latency.push(lat);
+  for (var i = 0; i < numRequests; i++) (function (i) {
+    makeRequest(function(l) {
+      lat[i] = l;
+      c--;
+      if (c === 0) run();
+    });
+  })(i);
+}
+
+function makeRequest(cb) {
+  var opts = { host: host,
+               port: port,
+               uri: 'http://'+host+':'+port+'/bytes/12',
+               forever: true,
+               path: '/bytes/12' };
+  var pre = Date.now();
+  var req = http.get(opts, function(res) {
+    return cb(Date.now() - pre);
+  });
+}
+
+function finish() {
+  var data = [];
+  latency.forEach(function(run, i) {
+    run.forEach(function(l, j) {
+      data[j] = data[j] || [];
+      data[j][i] = l;
+    });
+  });
+
+  data = data.map(function (l, i) {
+    return l.join('\t')
+  }).join('\n') + '\n';
+
+  var fname = prefix +
+              'client_latency_' +
+              numRequests + '_' +
+              maxSockets + '_' +
+              runs + '.tab';
+  var path = require('path');
+  fname = path.resolve(__dirname, '..', 'out', fname);
+  fname = path.relative(process.cwd(), fname);
+  require('fs').writeFile(fname, data, function(er) {
+    if (er) throw er;
+    console.log('written: %s', fname);
+  });
+}