Node async test

main.js

'use strict';

const fs = require('fs');
const crypto = require('crypto');
const http = require('http');

// Current timestamp
const start = Date.now();

// Simple Logging util
const log = (name, ...args) => {
  const diff = Date.now() - start;
  const msg = `[${name.toUpperCase()}]: TIME: ${diff}ms`;
  process.stdout.write([msg, ...args, '\n\n'].join(' '));
};

function work() {
  process.nextTick(() => log('process.nextTick', 'Draining nextTicks queue'));

  setImmediate(() =>
    log('setImmediate', 'reached the end of the current loop iteration')
  );

  setTimeout(() => log('Timers'), 1000);

  queueMicrotask(() => log('Micro task'));

  // Some file IO
  fs.readFile(__filename, () => {
    log('File IO');
  });

  // Expensive hash
  crypto.pbkdf2('password', 'saltyyy', 10000, 512, 'sha512', () => {
    log(`pbkdf2`);
  });

  let count = 1000000000;

  // Some blocking code
  while (count) {
    count--;
  }

  log('Blocking', `count is ${count}`);
}

const server = http.createServer((req, res) => {
  log('REQ INCOMING', req.url);

  if (req.url?.includes('kill')) {
    server.close();
  }

  req.on('readable', () => {
    log('REQ READABLE');
    work();
  });

  req.on('end', () => {
    res.end();
  });

  req.on('close', () => {
    log(`REQ CLOSE`);
  });
});

process.on('exit', () => {
  log('EXIT', 'Event loop is down. Gotta go now...');
});

server.on('close', () => {
  log(`Server CLOSE`);
});

server.on('listening', () => {
  log(`Server listening`);
});

work(); // Initial run

server.listen(3000);

/** 
STDOUT:

[BLOCKING]: TIME: 478ms count is 0 

[PROCESS.NEXTTICK]: TIME: 481ms Draining nextTicks queue 

[SERVER LISTENING]: TIME: 481ms 

[MICRO TASK]: TIME: 481ms 

[PBKDF2]: TIME: 481ms 

[SETIMMEDIATE]: TIME: 482ms reached the end of the current loop iteration 

[FILE IO]: TIME: 482ms 

[TIMERS]: TIME: 1002ms 

**/