node-gearman - background job error

index.js

'use strict';

var Gearman = require('node-gearman');
var gearman = new Gearman('localhost', 4730);

var submit = function(workerName, payload, cb) {
    payload = JSON.stringify(payload);
    var result = '';
    var job = gearman.submitJob(workerName, payload);
    job.on('data', function(data) {
//         console.log('data1', data);
        data = data.toString('utf-8');
//         console.log('data2');
//         console.log(data);
        result += data.toString('utf-8');
//         console.log('r', result);
    });
    job.on('end', function() {
//         console.log('rrr', result);
        result = JSON.parse(result);
        console.log('Job completed', result);
        cb(null, result);
    });
    job.on('error', function(err) {
        console.log('Worker error', err);
        cb(err);
    });
};

var queue = function(workerName, payload, cb) {
    payload = JSON.stringify(payload);
    var result = '';
    var job = gearman.submitJob(workerName, payload, false, {
        'background': true
    });
    job.on('data', function(data) {
//         console.log('data1', data);
        data = data.toString('utf-8');
//         console.log('data2');
//         console.log(data);
        result += data.toString('utf-8');
//         console.log('r', result);
    });
    job.on('end', function() {
//         console.log('rrr', result);
        result = JSON.parse(result);
        cb(null, result);
    });
    job.on('error', function(err) {
        cb(err);
    });
};

gearman.on('connect', function() {

    console.log('Connected.');

    gearman.registerWorker('doSomething', function(payload, worker) {

        console.log('Incoming doSomething job', payload);

        payload = payload.toString('utf-8');

        try {
            console.log('Calling JSON.parse on payload: --%s--', payload);
            payload = JSON.parse(payload);
        } catch(err) {
            console.log('JSON.parse error', err);
            return worker.error(err);
        }

        console.log('Parsed payload', payload);

        return worker.end(JSON.stringify({
            'name': 'Tim'
        }));

    });

    setTimeout(function() {

        submit('doSomething', {
            'animals': ['cats', 'dogs']
        }, function(err, result) {
            if (err) throw new Error(err);
            console.log('result', result);
            process.exit();
        });

//         queue('doSomething', {
//             'animals': ['cats', 'dogs']
//         });

    }, 1000);

});

gearman.connect();