Slow connection to a nodejs application running on localhost (windows 7)

Question

Connection to localhost (web app based on express/node.js) during unit testing (mocha/supertest) on my laptop is slow compared to another equivalent machine.

Same hardware
Windows 7 x64
Similar network configuration (results from ipconfig, netsh interface ip show config, netsh interface ip show dns, ipconfig /displaydns...)
Same node.js/npm configuration (node.js v8.9.1 and npm 5.5.1)

I have already tried a few things:

Disable IPv6 (it is disable on both machines)
Add localhost into the hosts file
Flush DNS history (ipconfig /flushdns)
Disconnecting my ethernet cable (I have no wifi either. Tests are passing but are still slow)
Change from 'localhost' to '127.0.0.1' in the test
Delete all my npm dependencies and re-install them (in project folder, in C:\Users\myUser\AppData\Roaming\npm and C:\Users\myUser\AppData\Roaming\npm-cache, in C:\Users\myUser\AppData\Local\Microsoft\Typescript and C:\Users\myUser\AppData\Local\Temp
Reinstall node.js/npm/vs code/typescript
Update npm and node.js to the latest version

It is also worth mentioning that:

the delay is always about 3s
the delay is between the time I send the request and the time I receive it (cf. logs below)
the problem only happens with localhost. Connection to remote APIs is as fast as on the other laptop
the loading time of the node-modules is fast
no event loop latency (checked with event-loop-lag)
there is no delay if I start the application and try to access the api with a browser
there is no delay if I start the application and run the test with url specified (not using 'app'). I added the following code in the app: if(!module.parent) { app.listen(3000); }
if I send 2 tests to localhost/127.0.0.1 and port 3000, the 2nd test is fast (cf. below)

Some related posts I have read without success:
Firefox and Chrome slow on localhost; known fix doesn't work on Windows 7
How to figure out why my local host site takes so long to load?
Running sites on "localhost" is extremely slow
https://technet.microsoft.com/en-us/library/bb727023.aspx

I have created a dummy project to reproduce the problem.
app.js file:

'use strict';

const express = require('express');
const router = express.Router();


const app = express();

router.get('/api/v1/home', (req, res, _next) => {
  console.log('home api - request received - ', new Date().toUTCString());
  res.sendStatus(200);
});
app.use(router);

app.use(function (req, res) {
  res.status(404).send();
});

app.use((err, req, res, next) => {
  res.status(err.status || 500);
  console.log(err.message);
});

app.listen(3000);


module.exports = app;

app.test.js file:

'use strict';

const assert = require('assert');
const rp = require('request-promise');
const app = require('./app');
const supertest = require('supertest');


describe('', function () {

  it('1st mocha test run fast', async function () {
    const res = await new Promise((resolve, _reject) => {
      setTimeout(() => {
        resolve('ok');
      }, 100);
    });
    assert.equal(res, 'ok');
  });

  it('calling app api with supertest', async function () {
    console.log('home api supertest - send request - ', new Date().toUTCString());
    await supertest(app).get('/api/v1/home').expect(200);
  });

  it('calling app api with request-promise (127.0.0.1)', async function () {
    console.log('home api request-promise - send request - ', new Date().toUTCString());
    const res = await rp('http://127.0.0.1:3000/api/v1/home')
      .then(function (_htmlString) {
          return 'ok'; 
      })
      .catch(function (err) {
          console.log(err);
          return 'nok';
      });
    assert.equal(res, 'ok');
  });

  it('calling app api with request-promise (localhost)', async function () {
    console.log('home api request-promise - send request - ', new Date().toUTCString());
    const res = await rp('http://localhost:3000/api/v1/home')
      .then(function (_htmlString) {
          return 'ok'; 
      })
      .catch(function (err) {
          console.log(err);
          return 'nok';
      });
    assert.equal(res, 'ok');
  });

});

The result is as follows:

> mocha ./api.test.js --exit --timeout 5000

    √ 1st mocha test run fast (101ms)
home api supertest - send request -  Mon, 06 Aug 2018 02:47:23 GMT
home api - request received -  Mon, 06 Aug 2018 02:47:26 GMT
    √ calling app api with supertest (3020ms)
home api request-promise - send request -  Mon, 06 Aug 2018 02:47:26 GMT
home api - request received -  Mon, 06 Aug 2018 02:47:29 GMT
    √ calling app api with request-promise (127.0.0.1) (3011ms)
home api request-promise - send request -  Mon, 06 Aug 2018 02:47:29 GMT
home api - request received -  Mon, 06 Aug 2018 02:47:29 GMT
    √ calling app api with request-promise (localhost)

  4 passing (6s)

Thank you very much for your help

Slow connection to a nodejs application running on localhost (windows 7)

0 Answers0