NodeJS: SharedMemory: Memory sharing on every worker of cluster

cluster.js

const cluster = require('cluster');
const numCPUs = require('os').cpus().length;

//
// ** SharedMemory which is shared among every worker:
//

// dont use `var` 
SharedMemory = {
  // shared data:
  data: null,
  // used by a worker to update shared data:
  update: function(data) {
    cluster.worker.send(data);
  },
};


//
// ** Start workers:
//

if (cluster.isMaster) {
  for (let i = 0; i < numCPUs; i++) {
    cluster.fork();
  }
  cluster.on('exit', function(worker, code, signal) {
    console.log('worker ' + worker.process.pid + ' died');
  });

  Object.keys(cluster.workers).forEach(function(id) {
    console.log("id", id);
    let worker = cluster.workers[id];
    worker.on('message', function(data) {
      console.log("[cluster] onMessage:", data);
      SharedMemory.data = data;
      // sends the data updated to every worker:
      Object.keys(cluster.workers).forEach(id => {
        cluster.workers[id].send(SharedMemory.data);
      });
    });
  });

} else {
  //change this line to Your Node.js app entry point.
  require("./server.js");

  // receives data from master thread:
  process.on('message', function(data) {
    console.log(`[cluster] update SharedMemory.data of process:${process.pid}:`, data);
    // update:
    SharedMemory.data = data;
  });
}

// ### Start:
// $ node cluster.js

server.js

const express = require("express");
const app = express();
const cluster = require('cluster');
const myname = "worker" + cluster.worker.id;

app.get('/', function(req, res) {
  // SharedMemory is defined as global vars on cluster.js:
  console.log(`[${req.path}] Get SharedMemory.data:`, SharedMemory.data);
  res.end(JSON.stringify(SharedMemory.data));
});

app.get('/update', function(req, res) {
  let data = { msg: "message from " + myname };
  console.log(`[${req.path}] SharedMemory.update:`, data);
  SharedMemory.update(data);
  res.end(JSON.stringify(data));
});

app.listen(3000, function() {
  console.log("Running at PORT 3000");
});

/* 
## Usage
$ node cluster.js

## update shared data:
http://localhost:3000/update

## view current shared data:
http://localhost:3000/update

## Console log sample
id 1
id 2
id 3
id 4
Running at PORT 3000
Running at PORT 3000
Running at PORT 3000
Running at PORT 3000
[/] Get SharedMemory.data: null
[/] Get SharedMemory.data: null
[/] Get SharedMemory.data: null
[/update] SharedMemory.update: { msg: 'message from worker3' }
[cluster] onMessage: { msg: 'message from worker3' }
[cluster] update SharedMemory.data of process:7325: { msg: 'message from worker3' }
[cluster] update SharedMemory.data of process:7320: { msg: 'message from worker3' }
[cluster] update SharedMemory.data of process:7326: { msg: 'message from worker3' }
[cluster] update SharedMemory.data of process:7327: { msg: 'message from worker3' }
[/] Get SharedMemory.data: { msg: 'message from worker3' }
[/update] SharedMemory.update: { msg: 'message from worker2' }
[cluster] onMessage: { msg: 'message from worker2' }
[cluster] update SharedMemory.data of process:7326: { msg: 'message from worker2' }
[cluster] update SharedMemory.data of process:7320: { msg: 'message from worker2' }
[cluster] update SharedMemory.data of process:7325: { msg: 'message from worker2' }
[cluster] update SharedMemory.data of process:7327: { msg: 'message from worker2' }
[/] Get SharedMemory.data: { msg: 'message from worker2' }
[/] Get SharedMemory.data: { msg: 'message from worker2' }
*/