Unload Sprite Atlas from memory

In case someone happens to have weird memory occupation caused by sprite atlases: Delete your lib files. That fixed it for us. The lib files contain a huge amount of cached atlas files (ca. 11GB in our case). Cleaning that up got rid of the weird behaviour.

Hi! I have a similar problem, where I load the new scene, where the Atlas is not referenced in any way, but according to the Profiler, it still has a lot of references to it.

This is the code for when I am changing scenes:

 IEnumerator Transition(string fromScene, string toScene) {
             yield return SceneManager.UnloadSceneAsync(fromScene);
             yield return StartCoroutine(LoadSceneAndSetActive(toScene));
             yield return Resources.UnloadUnusedAssets();
         }
 
         IEnumerator LoadSceneAndSetActive(string sceneName) {
             yield return SceneManager.LoadSceneAsync(sceneName, LoadSceneMode.Additive);
             var newlyLoadedScene = SceneManager.GetSceneAt(SceneManager.sceneCount - 1);
             SceneManager.SetActiveScene(newlyLoadedScene);
         }

Am I unloading the assets correctly? If I get rid of the SpriteAtlases, then I do not have any references to any of the sprites in the previous scene, so my conclusions is that is has to do something with SpriteAtlas.

Anyone got the same problem as I? Or am I profiling wrong? I have also tried to profile with the MemoryProfiler (https://bitbucket.org/Unity-Technologies/memoryprofiler) where when I select the atlas it says: "No root is keeping this object alive. It will be collected next UnloadUnusedAssets() or scene load"

If you use the SpriteAtlasManager callbacks, you can load and unload the Atlases yourself, instead of going through the database.

See example in https://github.com/jconstable/SpriteSleeper

The Memory Profiler Module doesn't show you the full reference chain from your C# scripts and it gives cryptic remarks if something is kept around because of Hide flags, like the Editor only flag: HideAndDontSave.

These Flags might keep these sprite atlases around in memory in the Editor for Editor purposes (like generating, regenerating or displaying their preview). Be sure to make a Development builds and profile that. Also try out the Memory Profiler Package that shows the managed references to these Atlases. It also shows the HideFlags in the Advanced foldout of the Selected Item Details section.