Example fork process to handle intesive work load to avoid block the main process in Node.js

heavy_operation.js

/**
 * Example to simulate a intesive work, sum the value recieved
 * @param {number} value
 */
const handlerHeavyOperation = (value = 0) => {
  let res = value;
  for (let i = 0; i < 90000; i++) {
    res += i;
  }
  return res;
};

// Listener the message and send the result to the main process
process.on("message", (value) => {
  const result = handlerHeavyOperation(value);
  process.send(result);
});

index.js

const express = require("express");
const { fork } = require("child_process");

const app = express();

const port = process.env.PORT || 3001;

// Endpoint with heavy operation
app.get("/heavy", (req, res) => {
  // Retrieve the value from query-params
  const { value } = req.query;
  // Create a fork process to handle the heavy operation
  const process = fork("./heavy_operation");
  // Send the value recieved
  process.send(value);
  // Listener when the operation is finished
  process.on("message", (result) => res.json({ result }));
});

app.listen(port, () => {
  console.log(`API listen in port ${port}`);
});