async.parallel not working like asynchronous in node js

Question

I have a below code.

var async = require('async');

async.parallel({

        f2: function(callback){
            for (var i=0;i< 100000000;i++){

            }
            console.log("f2");
            callback(null,"function 2");
        },
        f1: function(callback){

            console.log("f1");
            callback(null,"function 1");
        },

    },
    function(err, results) {
        console.log(results);
    });

and I run above...

result:

f2
f1
{ f2: 'function 2', f1: 'function 1' }

Why first result f2 ? Why not f1? f1 function is simple more than f2 function.

I think.. I cant make like asynchronous.

I don't want use SetTimeOut , proccess.NextTick etc...

async is for managing asynchronous code. Your code isn't asynchronous. — robertklep
– robertklep, Commented Aug 24, 2017 at 18:16

AlexBenoit · Accepted Answer · 2017-08-24 18:13:41Z

1

The function parallel() is about kicking-off I/O tasks in parallel, not about parallel execution of code. If your tasks do not use any timers or perform any I/O, they will actually be executed in series. Any synchronous setup sections for each task will happen one after the other. JavaScript remains single-threaded. Reference: https://caolan.github.io/async/docs.html#parallel

edited Aug 24, 2017 at 18:13

answered Aug 23, 2017 at 21:09

AlexBenoit

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2 Comments

Hüsamettin Kılsızfırça Over a year ago

I dont think so.. they dont start same time.

Hüsamettin Kılsızfırça Over a year ago

I can not see the console log of the f1 function before the f2 function is finished

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