Course Vector

Notes: Loop Optimizations

Here is some testing I did to determine the best kind of loop to use in AS3. In the end the fastest I determined was a simple reverse while loop. Below is the results with the code for my testing beneath that. Where I could, I tried to run 1 million items in the collection. If I was unable to do that (the program would crash) I would run 500k items. From what I have learned, using the Array.forEach() is kinda expensive for what it does. Standard for() loops aren’t too bad, but the for…in() loops are even worse than the Array.forEach(). If you know of anything faster methods or maybe I tested incorrectly please let me know!

package {

	import flash.display.MovieClip;
	import flash.utils.getTimer;
	import flash.utils.Dictionary;

	public class LoopTest extends MovieClip {
		private var l:int;
		private var list:Array = new Array();
		private var dict:Dictionary = new Dictionary();
		private var obj:Object = new Object();

		public function LoopTest() {
			var i:uint;

			//Create the source array
			for(i = 0; i < 1000000; i++) {
				list.push(Math.random());
			}
			l = list.length;
			trace("List of " + l + " elements.");

			// Create the source dictionary
			/*for (i = 0; i < 500000; i++) {
				var n:Number = Math.random();
				dict[n] = n;
			}*/

			// Create the source object
			/*for (i = 0; i < 500000; i++) {
				var n:Number = Math.random();
				obj[n] = n;
			}*/

			// Create the source dictionary 2
			/*for (i = 0; i <= 500000; i++) {
				dict[i] = Math.random();
				dict["length"] = i;
			}
			trace("Dictionary of " + dict["length"] + " elements.");*/
		}

		public function test000():void {
			var ts:Number = getTimer();
			for(var i:Number = 0; i < list.length; i++) {
				var z:Number = Math.random();
			}
			trace("for() [Number &amp; list.length]: " + (getTimer() - ts) + "ms");
		}

		public function test00():void {
			var ts:Number = getTimer();
			for(var i:uint = 0; i < list.length; i++) {
				var z:Number = Math.random();
			}
			trace("for() [uint inline &amp; list.length]: " + (getTimer() - ts) + "ms");
		}

		public function test0():void {
			var ts:Number = getTimer();
			var i:uint;
			for(i = 0; i < list.length; i++) {
				var z:Number = Math.random();
			}
			trace("for() [uint &amp; list.length]: " + (getTimer() - ts) + "ms");
		}

		public function test1():void {
			var ts:Number = getTimer();
			var i:uint;
			for(i = 0; i < l; i++) {
				var z:Number = Math.random();
			}
			trace("for() [uint &amp; l]: " + (getTimer() - ts) + "ms");
		}

		public function test2():void {
			var ts:Number = getTimer();
			var i:int;
			var l2:int = l - 1;
			for(i = l2; i >= 0; i--) {
				var z:Number = Math.random();
			}
			trace("for() [uint &amp; l reverse]: " + (getTimer() - ts) + "ms");
		}

		public function test3():void {
			var ts:Number = getTimer();
			var j:Number;
			for each(j in list) {
				var z:Number = Math.random();
			}
			trace("for each in(): " + (getTimer() - ts) + "ms");
		}

		public function test4():void {
			var ts:Number = getTimer();
			var m:String;
			for (m in list) {
				var z:Number = Math.random();
			}
			trace("for in(): " + (getTimer() - ts) + "ms");
		}

		public function test5():void {
			var ts:Number = getTimer();
			var i:int = 0;
			while(i < l) {
				var z:Number = Math.random();
				i++;
			}
			trace("while() [i < l]: "+(getTimer()-ts)+"ms");
		}

		public function test6():void {
			var ts:Number = getTimer();
			var i:int = l - 1;
			while(i--) {
				var z:Number = Math.random();
			}
			trace("while() [i--]: "+(getTimer()-ts)+"ms");
		}

		public function test7():void {
			var ts:Number = getTimer();
			var i:uint = l;
			while( i-- > 0 ){
				var z:Number = Math.random();
			}
			trace("while() [i-- > 0]: "+(getTimer()-ts)+"ms");
		}

		public function test8():void {
			var ts:Number = getTimer();
			var i:int = l - 1;
			do {
				var z:Number = Math.random();
			} while (i--);
			trace("do while(): "+(getTimer()-ts)+"ms");
		}

		public function test18():void {
			var ts:Number = getTimer();
			list.forEach(doRandom);
			trace("Array.forEach(): "+(getTimer()-ts)+"ms");
		}

		private function doRandom(item:*, index:int, arr:Array):void {
            var z:Number = Math.random();
        }

		// Dictionary Tests

		public function test9():void {
			var ts:Number = getTimer();
			var d:Dictionary = dict, e:Object;
			for each (e in d) {
				var z:Number = Math.random();
			}
			trace("Dictionary for each in() [local vars]: "+(getTimer()-ts)+"ms");
		}

		public function test10():void {
			var ts:Number = getTimer();
			var e:Object;
			for each (e in dict) {
				var z:Number = Math.random();
			}
			trace("Dictionary for each in(): "+(getTimer()-ts)+"ms");
		}

		public function test11():void {
			var ts:Number = getTimer();
			for each (var e:Object in dict) {
				var z:Number = Math.random();
			}
			trace("Dictionary for each in() [inline]: "+(getTimer()-ts)+"ms");
		}

		// Object Tests

		public function test12():void {
			var ts:Number = getTimer();
			var o:Object = obj, e:Object;
			for each (e in o) {
				var z:Number = Math.random();
			}
			trace("Object for each in() [local vars]: "+(getTimer()-ts)+"ms");
		}

		public function test13():void {
			var ts:Number = getTimer();
			var e:Object;
			for each (e in obj) {
				var z:Number = Math.random();
			}
			trace("Object for each in(): "+(getTimer()-ts)+"ms");
		}

		public function test14():void {
			var ts:Number = getTimer();
			for each (var e:Object in obj) {
				var z:Number = Math.random();
			}
			trace("Object for each in() [inline]: "+(getTimer()-ts)+"ms");
		}

		// Dictionary Tests 2

		public function test15():void {
			var ts:Number = getTimer();
			var i:int = 0;
			var l:int = dict["length"];
			while(i < l) {
				var z:Number = Math.random();
				i++;
			}
			trace("dictionary while() [i < l]: "+(getTimer()-ts)+"ms");
		}

		public function test16():void {
			var ts:Number = getTimer();
			var i:int = dict["length"] - 1;
			while(i--) {
				var z:Number = Math.random();
			}
			trace("dictionary while() [i--]: "+(getTimer()-ts)+"ms");
		}

		public function test17():void {
			var ts:Number = getTimer();
			var i:uint = dict["length"];
			while( i-- > 0 ){
				var z:Number = Math.random();
			}
			trace("dictionary while() [i-- > 0]: "+(getTimer()-ts)+"ms");
		}
	}
}

Tags: loops, optimization

1 Comment to Notes: Loop Optimizations

Leave a comment