Load Balancing NodeJS APIs with Clustering

Understand how we can optimize NodeJS APIs with the cluster module

Creating a basic server with Express

const express = require('express');
const PORT = 3000;

const app = express();
console.log(`Worker ${process.pid} started`);
app.get('/', (req, res) => {
  res.send('Hello World!');
});

app.listen(PORT, () => {
  console.log(`App listening on PORT ${PORT}`);
});

Now let us build a basic API that performs a CPU intensive task.

app.get('/api', function (req, res) {
  console.time('slowApi');
  const baseNumber = 7;
  let result = 0;
  for (let i = Math.pow(baseNumber, 7); i >= 0; i--) {
    result += i;
  }
  console.timeEnd('slowApi');

  console.log(`Result number is ${result} - on process ${process.pid}`);
  res.send(`Result number is ${result}`);
});

For a test duration of 20 seconds, with 150 requests per second and a concurrency of 10, these were the results

Target	API Without Clustering	API With Clustering
Completed requests	2717	2931
Total Errors	629	0
Mean Latency	1342.7 ms	32.4 ms
Longest Request	2336 ms	239 ms

Nedwize/cluster-node

Load Balancing NodeJS APIs with Clustering