Node js performance in request process

Question

Consider this code:

var http = require("http");
http.createServer(function(request, response) {
    for (var i = 0; i < 1000000; i++) {
        console.log("Request received");
    }
    response.writeHead(200, {
        "Content-Type": "text/plain"
    });
    response.write("Hello World");
    response.end();
}).listen(8888, "127.0.0.1");

If we run this code,we should wait for many minute too get response.But if run a for without console.log("Request received"); in a for we get response with high speed? Why?

Answer 1

Simply, one loop in a empty "for" takes nearly null time. But a output with console.log() need a bunch more time and its also synchronous.

Answer 2

First of all starting with node.js v0.6 , console.log() is synchronous (ie. it blocks the main event loop.)

You're writing around 17MBs to stdout on each request. It might take a few minutes for server to respond.

Answer 3

I think because write console.log("Request received"); in console get time process.

Answer 4

console.log is pretty slow like any other print/echo/sysout that does something on your STDOUT console.

EDIT: In addition to that, the interpreter will simply skip the loop if there is no operation in it. If you actually do something in it, it will of course take time.