Bug Why is this code leaking memory?

I have an editor window with a gradient that needs to be updated on certain changes. I noticed that it leaks memory. Moreover and what's worse is that the whole Unity menu system seems to break. When I click the same menu item over and over all of a sudden totally different editor windows appear instead of the one I clicked.

I guess it might be just a side effect - which shouldn't happen either way. Regarding the memory leak here's a minimal example.

Here's the code:

Code (CSharp):

1. using System;
2. using UnityEditor;
3. using UnityEditor.UIElements;
4. using UnityEngine;
5.  
6. public class MemoryLeak : EditorWindow
7. {
8.     [Serializable]
9.     public class MyData : ScriptableObject
10.     {
11.         public Gradient gradient;
12.     }
13.  
14.     [SerializeField]
15.     private MyData myData;
16.  
17.     private GradientField gradientField;
18.  
19.     [MenuItem("Testing/Memory Leak")]
20.     static void Init()
21.     {
22.         EditorWindow editorWindow = GetWindow(typeof(MemoryLeak));
23.         editorWindow.titleContent = new GUIContent("Memory Leak");
24.         editorWindow.Show();
25.     }
26.  
27.     public void OnEnable()
28.     {
29.         myData = myData == null ? ScriptableObject.CreateInstance<MyData>() : myData;
30.     }
31.  
32.     public void CreateGUI()
33.     {
34.         gradientField = new GradientField( "Gradient");
35.         gradientField.value = myData.gradient;
36.         gradientField.bindingPath = nameof(myData.gradient);
37.         rootVisualElement.Add(gradientField);
38.  
39.         SerializedObject so = new SerializedObject(myData);
40.         rootVisualElement.Bind(so);
41.     }
42.  
43.     public void Update()
44.     {
45.         // leak happens here
46.         Gradient gradient = gradientField.value;
47.         gradientField.value = gradient;
48.  
49.  
50.     }
51.     void OnDisable()
52.     {
53.         if (myData != null)
54.         {
55.             ScriptableObject.DestroyImmediate(myData);
56.             myData = null;
57.         }
58.     }
59.  
60. }
61.  

When you open the editor window using Testing > Memory Leak you can see the memory rise in the task manager.

For one the cause seems to be related to the assignment of a gradient in the Update() method. It also seems to be related to the bindingPath. What exactly causes this I'm actually not sure. Anyone got an idea?

ps: A different matter is why copy/paste context menu on the gradient label doesn't work if bindingPath isn't set. But then the leak is gone and that's the lesser evil.

 

I found the solution. I need to set bindingPath and invoke SetKeys on the gradient attribute of my ScriptableObject. The object of the GradientField mustn't be modified.

I created an issue nontheless since I've wasted too much time on this: Case 1392051

If re-assignment of fields causes leaks, the re-assignment must be prevented.