add another async.parallel example

[mariusa]

Hi,

Would it be possible please to add an example to the docs showing how to use async.parallel with a real-life use?
I simply don't get it how it should work from docs, from test/ or from
http://stackoverflow.com/questions/7236899/nodejs-async-same-arguments-to-an-array-of-functions

A nice example would be to read 2 files and make a db call (all these 3 in parallel, async), and then do something with all 3.

Here's a start, which I can't tell how to make it work:
https://gist.github.com/2030967

Thanks

[rlidwka]

Hm... usage here is the same as in other functions basically.

Ok, that's real-world example, hope it helps:

var mongo;
var httpserv;

async.parallel([
    function(callback) {
        var mongodb = require('mongodb');
        mongo = new mongodb.Db('project', new mongodb.Server("127.0.0.1", 27017, {auto_reconnect: true}));
        mongo.open(callback);
    },

    function(callback) {
        httpserv = require('http').createServer(function (request, response) {
            process_request(request, response);
        });
        httpserv.listen(1337, callback);
    },
], function() {
    Application.init(mongo, httpserv);
});

PS: variables should be return values of course... but you've asked about real life - how it is, not how it should be :D

[ianwalter]

Mariusa, I re-wrote your code example here: https://gist.github.com/4535307
async.parallel uses callbacks to populate the results array or object.
Someone should close this issue.

[brianmaissy]

Anyone else feel that the example in the docs isn't clear? @mariusa do you feel that this example adds something substantial that wasn't communicated by that example? If so, we should add it to the docs. If not, @caolan should close this.

[caolan]

I'd like the examples to be concise and clearly show the concept. I don't want them to teach JavaScript or Node.js. If people feel the underlying concept isn't described by the example then we should update it, otherwise I'll close this.

[brianmaissy]

Judging by the initial (incorrect) example proposal by @rlidwka the misunderstanding was more an issue of higher-order functions than the usage of async.parallel. I think the example in the docs is clear.

[caolan]

Agreed, closing.