gistfile1.js

//obj1 and obj2 are mongoose models


//Doesn't work
aync.parallel([obj1.save, obj2.save], function(err, results){
  //do stuff after both objects save
});

//Works
aync.parallel([obj1.save.bind(obj1), obj2.save.bind(obj2)], function(err, results){
  //do stuff after both objects save
});

async.map([ obj1, obj2 ], function(obj, callback) {
  obj.save(callback)
}, function(err, results) {
  console.log('err', err, 'results', results);
});