gistfile1.js

var fs = require ('fs'),
  async = require ('async');


var q = async.queue(function (task, callback){
	fs.appendFile('UIDs.txt', task.value + '\n');
	callback();
}, 250);

for (i = 1; i <= 1972100; i++) {
	q.push({'value' : i}, function (err) {});		
}