NodeJS Cluster how share object array across workers

Question

So I have setup a simple nodejs cluster game, I am new to nodejs. basically players connect to to my worker using socket.io then they get created to a Player Object then added to my PlayerManager.LIST array. Now this causes me some issues as the PlayerManager.LIST is on each of workers and are not sync'd.

So my question is, is there a better way of doing this so that if I connect to worker 2 I see same player list as worker 1's.

Structure at the moment:

app.js
-> worker
->-> PlayerManager (Contains List)
->->-> Player

Git Repo: https://github.com/mrhid6/game_app_v2

Answer 1

NodeJS Clusters are based on Nodejs Child Processes. In child processes you can send data between parent (Master in cluster) and child (worker in cluster) via messages over IPC channel. You can do the same with clusters using message events

var cluster = require('cluster');
var _ = require('lodash');
var http = require('http');
var workers = [];
var workerCount = 4;

if (cluster.isMaster) {
  for (var i = 0; i < workerCount; i++) {
    var worker = cluster.fork();

    worker.on('message', function(msg) {
      if (msg.task === 'sync') {
            syncPlayerList(msg.data);
      }
    });
  }
  workers.push[worker];

} else {
  var worker = new Worker();
  process.on('message', function(msg) {
    if (msg.task === 'sync') {
        worker.playerList = msg.data;
    }
  });
}

function syncPlayerList (playerList) {
    _.forEach(workers, function (worker) {
        worker.send({
            task: 'sync',
            data: playerList
        });
    });
};


// worker class
function Worker() {
    this.playerList = [];
}

Worker.prototype.sendSyncEvent = function () {
    process.send({
        task: 'sync',
        data: this.playerList
    })
};