Setup several forked processes in node.js

work_dist_index.js

const { fork } = require('child_process');

let awaiting = {}; // array of payload ids awaiting responses from workers
let awaiting_lastid = 1; // incrementing payload ids
let worker_pool = [];

function sendPayload(id, payload) {
  payload.id = awaiting_lastid++; // set and add id
  awaiting[payload.id] = { worker: id, date: Date.now() }

  worker_pool[id].send(payload);
}

function receivePayload(id, payload) {
  switch (payload.type) {
    case 'meta.acknowledged':
      // the worker responded to our request
      delete awaiting[payload.obj.id];
      break;
    case 'error':
      // worker sent an error
      console.warn(`${id} error (${payload.obj.errcode}):`);
      console.warn(payload.obj.errmsg);
      console.warn('');
      break;
    default:
      console.warn(`${id} sent unknown payload type`);
      break;
  }
}

function setupWorkerPool(count = 4) {
  for (let i = 0; i < count; i++) {
    let worker = fork('./worker.js');
    worker.on('message', payload => receivePayload(i, payload));
    worker_pool.push(worker);

    sendPayload(i, { type: 'id.set', obj: { id: `${process.pid}__${i}` } });
  }
}

setupWorkerPool();

// Keep the program running forever (ctrl+c to exit)
setInterval(() => {}, Number.POSITIVE_INFINITY);