test-smaller.js

var exec = require('child_process').exec,
  Futures = require('futures'),
  pload = Futures.promise(),
  pdisk = Futures.promise(),
  pusage = Futures.promise();

function log() {
  console.log("event happened");
  console.dir(arguments);
}

exec('uptime', pload.fulfill);
exec('df -l -k |grep md0 |awk \'{print $3,$4}\'', pdisk.fulfill);
exec('vnstat --dumpdb |grep "m;0"', pusage.fulfill);

pload.when(log);
pdisk.when(log);
pusage.when(log);

function parseLoad(err, stdout, stderr) {
    var load = stdout.split('load average:');
    load = load[1].split(', ');
    return load;
}

function parseDisk(err, stdout, stderr) {
    return stdout;
}

function parseUsage(err, stdout, stderr) {
    return stdout.split(';');
}

Futures.join(pload, pdisk, pusage).when(function(loadArgs, diskArgs, usageArgs) {
    var result = [
      parseLoad.apply(null, loadArgs),
      parseDisk.apply(null, diskArgs),
      parseUsage.apply(null, usageArgs)
    ];
    console.log("\n\nall complete");
    console.dir(result);
});

test.js

var exec = require('child_process').exec,
  Futures = require('futures');

var getLoad = function() {
  var p = Futures.promise();
  console.log('load');
  exec('uptime', function(err, stdout, stderr) {
    var load = stdout.split('load average:');
    //load = load[1].slice(1,load[1].length-1);
    load = load[1].split(', ');
    //console.log(load);
    p.fulfill(err, load);
  });
  return p;
};

var getDiskUsage = function() {
  var p = Futures.promise();
  console.log('disk');
  var data = {};

  exec('df -l -k |grep md0 |awk \'{print $3,$4}\'', function(err, stdout, stderr) {

  var diskUsage = stdout.split(' ');
    p.fulfill(err, diskUsage);
  });
  return p;
};

var getIfUsage = function() {
  var p = Futures.promise();
  console.log('ifUsage');
  var data = {};

  exec('vnstat --dumpdb |grep "m;0"', function(err, stdout, stderr) {
    var ifUsage = stdout.split(';');
    //console.log(ifUsage);
    p.fulfill(err, ifUsage);
  });
  return p;
};

test = getLoad;
test2 = getDiskUsage;
test3 = getIfUsage;

var p = test().when(function(err, data) {
  console.log('test-callback');
  console.log(data);
});

var p2 = test2().when(function(err, data) {
  console.log('test2-callback');
  console.log(data);
});

var p3 = test3().when(function(err, data) {
  console.log('test3-callback');
  console.log(data);
});

Futures.join(p, p2, p3).when(function(arr) {
  console.log(arr);
});