TextureCache not being released from memory.

crooksy88

Using Scout I can see that as I dispose of my textureCache the GPU memory is not being released.
Would anyone have an idea as to why thsi is happening?

I have a list of 10 item renderers, each of which has it's own horizontal list which has 50 items(imageLoaders).

Each of the horizontal lists load in the same 50 images.
So in total I am loading 500 images.

Each of the image loaders has the same _scrollableImagesTextureCache assigned as the textureCache.

_imageLoader.textureCache = Main.galleryScreen._scrollableImagesTextureCache;
_imageLoader.textureSmoothing = TextureSmoothing.BILINEAR;

//Main.galleryScreen

public var _scrollableImagesTextureCache:TextureCache;
_scrollableImagesTextureCache = new TextureCache(50);

Once all images have been loaded the GPU is at 363,000KB.
(note that if I don't use textureCache the GPU usage at this point is exactly the same).

If I don't use textureCache and dispose of the list of 10 renderers, the GPU usage drops to 17,000KB.

But when using textureCache, when I dispose of the lists and textureCache the GPU memory only drops to 327,000KB.

These are the functions I'm using to dispose of the list and textureCache.

//within the imageLoader listItemRenderers

public function destroy():void {
	this.removeEventListener(starling.events.Event.REMOVED_FROM_STAGE, destroy);
	try{
	removeChild(_imageLoader, true);
	_imageLoader = null;
	} catch(e:Error) {
}

// the itemRenderers in the main list of 10 items contain these functions:

public function destroy():void {
	this.removeEventListener(starling.events.Event.REMOVED_FROM_STAGE, destroy);	
	clearList();
	_dataObject = null;
}

private function clearList():void {
	_list.removeEventListener(FeathersEventType.RENDERER_ADD, renderedAdded);
	_list.removeEventListener(FeathersEventType.RENDERER_REMOVE, renderedRemoved);
	_list.removeEventListener(feathers.events.FeathersEventType.SCROLL_COMPLETE, list_scrollHandler);
	removeChild(_list, true);
	_list = null;
	_listLayout = null;
	_renderer = null;
	_listCollection = null;
}

And then to remove the list containing the 10 items:

private function transitionOutCompleteHandler( event:Event ):void {
destroyRenderers();
}

private function destroyRenderers():void {		
			if (_items) {
				if (_items.length > 0) {
					for (var i:int = 0; i < _items.length; i++) {
						trace("GALLERY destroyRenderer");
						SlammerListItemRenderer(_list.itemToItemRenderer(_items[i])).destroy();
					}
				}
			}
		
		//remove the thumbnails
		clearList();
		clearTextureCache();	
}


private function clearList():void {
			_list.removeEventListener(starling.events.Event.UPDATE, list_updateHandler);
			_list.removeEventListener(FeathersEventType.RENDERER_ADD, rendererAdded);
			_pullView.removeEventListener(FeathersEventType.PULLING, pullView_pullingHandler);

			removeChild(_list, true);
			_vl = null;
			_renderer = null;
			_items.length = 0;
			_items = null;
			_listCollection = null;
			_list = null;
}

		

private function clearTextureCache():void {
		trace("_scrollableImagesTextureCache.maxUnretainedTextures",_scrollableImagesTextureCache.maxUnretainedTextures);

for (var i:int = 0; i < _scrollableImagesTextureCache.maxUnretainedTextures; i++) {
trace("_scrollableImagesTextureCache.hasTexture", _scrollableImagesTextureCache.hasTexture("https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_"+i+"_512.jpg")); //true
trace("_scrollableImagesTextureCache.getRetainCount", _scrollableImagesTextureCache.getRetainCount("https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_"+i+"_512.jpg")); //0
}
			
_scrollableImagesTextureCache.dispose();
for (var i:int = 0; i < _scrollableImagesTextureCache.maxUnretainedTextures; i++) {
trace("_scrollableImagesTextureCache.hasTexture", _scrollableImagesTextureCache.hasTexture("https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_"+i+"_512.jpg")); //false
trace("_scrollableImagesTextureCache.getRetainCount", _scrollableImagesTextureCache.getRetainCount("https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_"+i+"_512.jpg")); //0
}
		
_scrollableImagesTextureCache = null;
trace("_scrollableImagesTextureCache", _scrollableImagesTextureCache); //blank
		
}

joshtynjala

I don't know why your GPU memory isn't going down, but I checked the source code, and calling textureCache.dispose() will dispose all textures, even if they are still retained. As long as you are sure that is getting called, then all textures should be removed from memory.

https://github.com/feathersui/feathersui-starling/blob/v4.1.1/source/feathers/utils/textures/TextureCache.as#L123-L140

crooksy88

I've realised what is happening here but not sure why. It seems that despite me creating only one instance of a textureCache and assigning that to all imageLoaders, a different instance of a cache is being created for each list.

I have a parent class (Main.gallerySlammerScreen) which creates and assigns the instance of the textureCache.

private static var _scrollableImagesTextureCache:TextureCache;

public function get scrollableImagesTextureCache():TextureCache {
	return _scrollableImagesTextureCache;
}

Within this parent class I creat the instance:

if (!_scrollableImagesTextureCache){
	_scrollableImagesTextureCache = new TextureCache( 50 );
}

I then create a list of 10 items, each item has it's own scrollable sublist of imageLoaders.

And each of these imageLoaders sets the textureCache to the sme instance:

_imageLoader.textureCache = Main.gallerySlammerScreen.scrollableImagesTextureCache;

On each imageLoader I check to see if the texture is in the cache.

if (Main.gallerySlammerScreen.scrollableImagesTextureCache.hasTexture(_localThumbUrl)){
	trace(">>FOUND IN TEXTURECACHE",_localThumbUrl);
} else {
	trace(">>NOT FOUND IN TEXTURECACHE",_localThumbUrl);
}

_imageLoader.source = _localThumbUrl;
addChild(_imageLoader);

But this always outputs the >>NOT FOUND trace.

Would you have any ideas why this is happening?

TIA, Mark

joshtynjala

I wonder if the TextureCache might be null when you assign it to the ImageLoader. Maybe add a trace() here to check:

trace(Main.gallerySlammerScreen.scrollableImagesTextureCache);
_imageLoader.textureCache = Main.gallerySlammerScreen.scrollableImagesTextureCache;

I mention this because you return the variable here...

public function get scrollableImagesTextureCache():TextureCache {
	return _scrollableImagesTextureCache;
}

but you create it somewhere else...

if (!_scrollableImagesTextureCache){
	_scrollableImagesTextureCache = new TextureCache( 50 );
}

So perhaps things are happening in a different order than you've assumed.

Moving the creation into the getter, like this, might help:

public function get scrollableImagesTextureCache():TextureCache {
	if (!_scrollableImagesTextureCache){
		_scrollableImagesTextureCache = new TextureCache( 50 );
	}
	return _scrollableImagesTextureCache;
}

crooksy88

Many thanks for the suggestions Josh. Unfortunately they didn't fix the issue.

But whilst testing those I've noticed another aspect.

If I create just one List of imageLoaders but add each image twice (so 100 imageLoaders in total but only 50 unique URLs) using the following code:

private function loadThumbnail():void {
		
if (!_imageLoader){
_imageLoader = new ImageLoader();
_imageLoader.maintainAspectRatio = false;
trace("IS TEXTURECACHE AVAILABLE?",Main.gallerySlammerScreen.scrollableImagesTextureCache);	
_imageLoader.textureCache = Main.gallerySlammerScreen.scrollableImagesTextureCache;
_imageLoader.textureSmoothing = TextureSmoothing.BILINEAR;
}
			
_imageLoader.addEventListener( Event.COMPLETE, onImageLoadComplete );
_imageLoader.addEventListener( IOErrorEvent.IO_ERROR, iOError );
_localThumbUrl = Main.IMAGESTORE_URL+DataStore.currentlyUsedAgentID+"_"+DataStore.currentSelectedPID+"/"+this._data._url512;
		
//test to see if the image is in the texturecache.
if (Main.gallerySlammerScreen.scrollableImagesTextureCache.hasTexture(_localThumbUrl)){
trace(">>FOUND IN TEXTURECACHE",_localThumbUrl);
} else {
trace(">>NOT FOUND IN TEXTURECACHE",_localThumbUrl);
}
		
_imageLoader.source = _localThumbUrl;
addChild(_imageLoader);
}

I get the same trace output for all imageLoaders e.g.:

IS TEXTURECACHE AVAILABLE? [object TextureCache]
>>NOT FOUND IN TEXTURECACHE https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_50_512.jpg
IS TEXTURECACHE AVAILABLE? [object TextureCache]
>>NOT FOUND IN TEXTURECACHE https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_50_512.jpg

I would have expected the second imageLoader to find the texture.

However, once the list has been created and displayed, when removing the list and clearing the textureCache,
if I test to see if the hasTexture is true, it is?

public function clearTextureCache():void {

or (var i:int = 0; i < _scrollableImagesTextureCache.maxUnretainedTextures; i++) {
trace("_scrollableImagesTextureCache.hasTexture", "https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_"+i+"_512.jpg",_scrollableImagesTextureCache.hasTexture("https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_"+i+"_512.jpg")); //true
trace("_scrollableImagesTextureCache.getRetainCount for", "https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_"+i+"_512.jpg", _scrollableImagesTextureCache.getRetainCount("https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_"+i+"_512.jpg")); //0
}
			
_scrollableImagesTextureCache.dispose();
		
_scrollableImagesTextureCache = null;
trace("_scrollableImagesTextureCache", _scrollableImagesTextureCache); //blank
}

_scrollableImagesTextureCache.hasTexture https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_50_512.jpg true
_scrollableImagesTextureCache.getRetainCount for https://www.propertytours.tv/movies/imageStore/9405_125518781/L_125518781_50_512.jpg 0

It seems as if there is a delay in registering the texture key into the cache.
Any ideas why this is happening?

Thanks, Mark

joshtynjala

If the first ImageLoader hasn't completed loading the image when the second ImageLoader checks the cache, then the second ImageLoader won't be able to find the texture in the cache. It doesn't become available to other ImageLoader instances until it completes loading and a texture has been created and stored in the cache.

crooksy88

So are you saying the texturecache isn’t compatible with a list if the list items all load in the same image or images?

joshtynjala

If there are multiple simultaneous requests for the same image that isn't yet in the cache, the image bytes/bitmap will be (temporarily) loaded into memory from the URL/file separately for each request. The first ImageLoader to complete loading will create a texture and populate the cache. When the second ImageLoader completes loading, it will first check the cache to see if it had been populated by another ImageLoader in the meantime. If the second ImageLoader finds that cache has been populated, it will to avoid creating a second texture. Instead, it will will dispose the bytes/bitmap that it loaded and use the cached texture instead.

It may temporarily use too much memory from the duplicate loads, but eventually, all ImageLoader instances will end up using the same cached texture.

crooksy88

Thanks Josh.
To get this working correctly I have created 50 separate imageLoaders, each assigned the same textureCache and loading in a different image.

Importantly, the imageLoader needs to be added to the stage before the image is loaded and texture created.

Once I have all 50 images loaded I remove the imageLoaders, null them and go on to create my list which does indeed use the single textureCache for all instances.

Without doing this first procedure, I can't see, when a list is created and added to the stage, how an image can be loaded and texture created fast enough so it would be available for other listItemRenderers to use.