improved version test nodejs performance

nodejs_perf_v2.js

var fs = require('fs');
var from = new Date().getTime();
var waiting = 0;
fs.readFile("test.mp4",function(err, data) {
    if(err)
        console.log("read error: ", err);
    else { 
		for (var i = 1; i <= 10; i++) {
			waiting ++;
			fs.writeFile(__dirname + "/new.mp4", data , function(err) {
			    if(err) {
			        console.log("write error: ", err);
			    } else {
					waiting --;
					complete();			
			    }
			}); 
		}
    }
});

function complete() {
    if (!waiting) {
		console.log("length: ", (new Date().getTime() - from)/1000);
    }
}

console.log("Start", new Date().getTime());
var fs = require('fs');
for (var i = 1; i < 10; i++) {
fs.readFile("test.mp4",function(err, data) {
if(err)
console.log("read error: ", err);
else {
fs.writeFile(__dirname + "/new.mp4", data , function(err) {
if(err) {
console.log("write error: ", err);
}
});
}
});
};
process.on('exit', function () {
console.log("Finished", new Date().getTime());
});