when.sequence execution penalty

perf.js

//var PerfTime = require('perf-time');
//var _ = require('underscore');

var Perf = module.exports = function() {
  this.startTime = null;
  // this.t = new PerfTime();
  this.t = {
    get: function() {
      return Date.now();
    }
  };
  this.logs = [];
  this.tags = [];
};

var _singleton;
Perf.getSingleton = function() {
  if (_singleton) {
    return _singleton;
  }

  return (_singleton = new Perf());
};

Perf.prototype.start = function() {
  this.startTime = this.t.get();
};

Perf.prototype.log = function(optsTag) {
  this.logs.push(this.t.get());
  this.tags.push(optsTag || '');
};


Perf.prototype._getPercent = function(whole, fragment) {
  return this._round(fragment / whole);
};

Perf.prototype._round = function(num) {
  return num;//Math.round(num * 100) / 100;
};

Perf.prototype.result = function() {

  var max = 0;
  var min = 0;
  var diffs = [];
  var cur = 0;
  this.logs.forEach(function(stamp, index) {
    // console.log('stamp:', stamp, index, !_.isNumber(this.logs[index - 1]), stamp - this.logs[index - 1], this.tags[index]);
    if (!this.logs[index - 1]) {
      return;
    }
    var diff = stamp - this.logs[index - 1];
    diffs.push(diff);
    max = (diff > max ? diff : max);
    min = (diff < min ? diff : min);
  }, this);

  var totalLogs = this.logs.length;
  var mean = 0;
  if ( 1 < diffs.length) {
    mean = diffs.reduce(function(a, b){return a+b;}) / totalLogs;
    mean = this._round(mean);
  }

  var total = this.logs[totalLogs - 1] - this.startTime;

  return {
    stats: {
      max: max,
      min: min,
      mean: mean,
      total: total
    },
    logs: this.logs,
    tags: this.tags,
    diffs: diffs,
    firstLog: this.startTime,
    lastLog: this.logs[totalLogs - 1]
  };

};

sequence.perf.js

var when   = require('when');
var sequence = require('when/sequence');

var Perf = require('./perf');
var perf = new Perf();

var noop = function(){};


var main = function() {
  var def = when.defer();
  var def2 = when.defer();
  var def3 = when.defer();

  var getDef2 = function() { return def2.promise;};
  var getDef3 = function() { return def3.promise;};

  sequence([getDef2, getDef3]).then(def.resolve, def.reject);

  setTimeout(def2.resolve);
  setTimeout(def3.resolve);

  return def.promise;
};

console.log('starting...');
perf.start();

var promises = [];

var loops = 500;
var promise;

function asyncNew(i) {
  setTimeout(function(){
    perf.log('Adding main:' + i);
    promise = main();
    promises.push(promise);

    if (loops === i + 1){
      when.all(promises).then(restore);
    }
  });
}

perf.log('before for');
for (var i = 0; i < loops; i++) {
  perf.log(i);
  asyncNew(i);
}

perf.log('after for');

function restore(proms) {
  perf.log('in restore');
  var nowTime = Date.now();
  var res = perf.result();
  console.log('Diff startTime:', nowTime - res.firstLog);
  console.log('proms:', proms.length);
  console.log('stats:', res.stats);
  console.log('diffs:', res.diffs.join(' '));
  console.log('diffs len:', res.diffs.length);
}

clone it, install when and run it:

https://gist.github.com/5376317.git

npm install when

node sequence.perf.js