index.js
function (err) {
        var message = {cmd: 'startupComplete', pid: process.pid};
        if (err) {
            console.warn(err.stack);
            message.error = err.message;
        }
        process.send(message);
    }
function (err) {
        var message = {cmd: 'startupComplete', pid: process.pid};
        if (err) {
            console.warn(err.stack);
            message.error = err.message;
        }
        process.send(message);
    }
function ( err ) { var message = { cmd : 'startupComplete' , pid : process . pid } ; if ( err ) { console . warn ( err . stack ) ; message . error = err . message ; } process . send ( message ) ; }
Use this callback to notify back to the cluster master that we're started, either successfully or with error
Use this callback to notify back to the cluster master that we re started either successfully or with error