using default cluster module for custom purposes with linux signal interface

npm install cluster_custom
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Common usage approach. Note that app.js has it's own interface :

module.exports = {
  startServer : startServer // return httpServer (or another one) instance
var app = require(__dirname + '/server/app');
var clusterHelper = require('./node_user_modules/cluster_helper');
var clusterInstance = new clusterHelper();
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