I was wondering if we can measure the time it takes for an http request to be pleted using node.js. Modifying slightly an example from the documentation (here), one can easily write down the following code.

var http = require('http');
var stamp1 = new Date();
var stamp2, stamp3, stamp4;
var options = {
  hostname: 'www.google',
  port: 80,
  path: '/upload',
  method: 'POST'
};

var req = http.request(options, function(res) {
  stamp3 = new Date();
  console.log('STATUS: ' + res.statusCode);
  console.log('HEADERS: ' + JSON.stringify(res.headers));
  res.setEncoding('utf8');
  res.on('data', function (chunk) {
    console.log('BODY: ' + chunk);
  });
  res.on('end', function () {
    stamp4 = new Date();
    console.log ("Stamp 3: " + stamp3);
    console.log ("Stamp 4: " + stamp4);
  });
});
req.on('error', function(e) {
  console.log('problem with request: ' + e.message);
});

// write data to request body
req.write('data\n');
req.write('data\n');
req.end();

stamp2 = new Date();
console.log ("Stamp 1: " + stamp1);
console.log ("Stamp 2: " + stamp2);

I was wondering if we can measure the time it takes for an http request to be pleted using node.js. Modifying slightly an example from the documentation (here), one can easily write down the following code.

var http = require('http');
var stamp1 = new Date();
var stamp2, stamp3, stamp4;
var options = {
  hostname: 'www.google.',
  port: 80,
  path: '/upload',
  method: 'POST'
};

var req = http.request(options, function(res) {
  stamp3 = new Date();
  console.log('STATUS: ' + res.statusCode);
  console.log('HEADERS: ' + JSON.stringify(res.headers));
  res.setEncoding('utf8');
  res.on('data', function (chunk) {
    console.log('BODY: ' + chunk);
  });
  res.on('end', function () {
    stamp4 = new Date();
    console.log ("Stamp 3: " + stamp3);
    console.log ("Stamp 4: " + stamp4);
  });
});
req.on('error', function(e) {
  console.log('problem with request: ' + e.message);
});

// write data to request body
req.write('data\n');
req.write('data\n');
req.end();

stamp2 = new Date();
console.log ("Stamp 1: " + stamp1);
console.log ("Stamp 2: " + stamp2);

Now let me e to my point. On the response one can easily measure the time it takes for the response, since in the beginning stamp3 is set and on end stamp 4 is set. So, in principle for relatively large amounts of data these two timestamps will be different.

However, the question that I have is whether stamps 1 and 2 actually measure what is happening when the request is being prepared and dispatched. In other words, is req.write(....) a synchronous operation? Based on node.js principles I would expect req.write(...) to be an asynchronous operation where one can pass an arbitrarily large document and then upon successful pletion we can have a callback knowing that the request has finished.

Comments?

• javascript
• node.js
• timing
• http-request

• 2 You may want to create a utility function to perform the measurement and you can get an actual duration out by using Date.now() while subtracting the second timestamp from the first timestamp. Also note you can measure in nanoseconds with process.hrtime. – Kevin Reilly Commented Sep 25, 2014 at 12:04
• Thanks, I like the process.hrtime suggestion because I was not aware of it! As of the subtraction, that is precisely my point eventually for the actual measurement. – MightyMouse Commented Sep 25, 2014 at 12:11

2 Answers 2

Two function already exist for that:

• console.time(id), start the timer
• console.timeEnd(id) end the timer, print id followed by the time in ms

So in your case:

var req = http.request(options, function(res) {
    console.time('Requete: '); //Begin to count the time
    stamp3 = new Date();
    console.log('STATUS: ' + res.statusCode);
    console.log('HEADERS: ' + JSON.stringify(res.headers));
    res.setEncoding('utf8');
    res.on('data', function (chunk) {
        console.log('BODY: ' + chunk);
    });
    res.on('end', function () {
        stamp4 = new Date();
        console.log ("Stamp 3: " + stamp3);
        console.log ("Stamp 4: " + stamp4);
        console.timeEnd('Requete: '); //Will print "Requete: X" with X being the time in ms
    });
});

The docs mention no callback, so I'm assuming req.write as well as res.end to be synchronous.

So in your case if you're referring to just that one request that you're initializing, I think the time measurement should be accurate. I don't expect the time difference to be very big though (perhaps even in the same milisecond).