load-tester-main.js

const { Worker } = require('worker_threads');
const path = require('path');

function runService(workerData) {
  return new Promise((resolve, reject) => {
    const worker = new Worker(path.resolve(__dirname, './worker.js'), { workerData });
    worker.on('message', resolve);
    worker.on('error', reject);
    worker.on('exit', (code) => {
      if (code !== 0)
        reject(new Error(`Worker stopped with exit code ${code}`));
    });
  });
}

const numWorkers = 100;
const promises = [];

for (let i = 0; i < numWorkers; i++) {
  promises.push(runService());
}

Promise.all(promises)
  .then(results => {
    results.forEach(result => {
      console.log(result);
    });
  })
  .catch(err => {
    console.error(err);
  });