# Unity: FMOD Reference Updater takes 15minutes to scan **URL:** \ **Category:** Unity\ **Tags:** mac, unity\ **Created:** [September 23, 2024, 4:48pm UTC](https://qa.fmod.com/t/unity-fmod-reference-updater-takes-15minutes-to-scan/22119 "2024-09-23T16:48:50Z")\ **Posts on this page:** 1\ **Showing post:** 28
**Author:** ![Ultroman](https://avatars.discourse-cdn.com/v4/letter/u/258eb7/32.png) [@Ultroman](https://qa.fmod.com/u/Ultroman)\ **Post date:** [May 28, 2026, 9:36pm UTC](https://qa.fmod.com/t/unity-fmod-reference-updater-takes-15minutes-to-scan/22119/28 "2026-05-28T21:36:36Z")
Our project hung during Event Reference Updater, too. I found out why and **fixed it**. Here’s the what and how, with a **full step-by-step guide at the bottom** on how to fix it. NOTE: I didn’t upload the fully fixed file, as I didn’t want to break any rules or laws, and also this way the fixes are likely to work for many different versions, since they are relatively simple. ## **Issue 1: Editor hangs indefinitely on certain prefabs** **GetGenericUpdateTasks()** recurses into sub-object fields without any depth limit. On prefabs with components that hold large or self-referential object graphs (e.g. object pools, manager classes with many collection fields), the recursive walk never finishes within a single EditorApplication.update tick, freezing the editor. ### **FIX** Add a depth guard at the top of **GetGenericUpdateTasks()**. Even going as deep as 8 still makes it ultra-fast. You can change this at your leisure. Whatever you set it to, it no longer continues branching forever. ## **Issue 2: Massive duplicate results and O(n²) cycle detection** An IEnumerable is used to track visited objects, calling **parents.Contains(value)** for cycle detection, which is incredibly slow! This also only detected direct ancestors in a linear chain, while diamond-shaped references (object A referenced by both B and C) were walked twice. On large graphs this degraded to **O(n²)**. ### **FIX** Replace the **IEnumerable parents** parameter with a **HashSet** for O(1) lookups, created once per top-level call and shared across all recursive calls. ## **Issue 3: Unmodified prefab instances found in scenes or nested under other prefabs, were reported as duplicate results** **GetEmitterUpdateTasks()** already correctly skips unoverridden prefab instances by checking **PrefabUtility.GetPropertyModifications()**, but **SearchGameObject()** calls **GetUpdateTasks()**, which routes non-emitter components to **GetGenericUpdateTasks()** which doesn’t check for that. This means every instance of a prefab placed in a scene or under another prefab is fully scanned, even if it has zero overrides, producing duplicate results for every field already reported on the source prefab asset. ### **FIX** In **SearchGameObject()**, skip any component that is part of a prefab instance with no property modifications on that component. # **Applying the fixes:** ### Fixing issue 1 We have to add a **depth** parameter to the **GetGenericUpdateTasks()** method, and all the recursive calls within it. Add the **depth** parameter at the end of the signature, like this…: ```csharp private static IEnumerable GetGenericUpdateTasks(object target, string subObjectPath = null, IEnumerable parents = null, int depth = 0) ``` …then add this as the first lines of the method… ```csharp if (depth > 8) yield break; ``` …then find the recursive calls to it, and add the **depth incrementation**. There are two foreach loops that call it, at the very bottom of the **GetGenericUpdateTasks()** method. Respectively, those lines become: ```csharp foreach (Task t in GetGenericUpdateTasks(item, FieldPath(subObjectPath, subObjectField.Name, index), parents, depth + 1)) ``` and ```csharp foreach (Task t in GetGenericUpdateTasks(value, FieldPath(subObjectPath, subObjectField.Name), parents, depth + 1)) ``` ### Fixing issue 2 We need to swap out the **IEnumerable parents** parameter for a **HashSet**. I chose to call it **visitedSet** instead, for clarity. To optimize the set comparisons, we will add an IEqualityComparer. Add this somewhere within the **EventReferenceUpdater** class…: ```csharp internal sealed class ReferenceEqualityComparer : System.Collections.Generic.IEqualityComparer { public static readonly ReferenceEqualityComparer Instance = new ReferenceEqualityComparer(); private ReferenceEqualityComparer() { } public new bool Equals(object x, object y) => ReferenceEquals(x, y); public int GetHashCode(object obj) => System.Runtime.CompilerServices.RuntimeHelpers.GetHashCode(obj); } ``` …then go to the signature of **GetGenericUpdateTasks()**, and swap out this…: ```csharp , IEnumerable parents = null ``` …for this…: ```csharp , HashSet visitedSet = null ``` …add these lines at the top of the method, right _ **after** _ the **depth** yield we added to fix **Issue 1** …: ```csharp if (visitedSet == null) visitedSet = new HashSet(ReferenceEqualityComparer.Instance); if (!target.GetType().IsValueType && !visitedSet.Add(target)) yield break; ``` …scroll down a bit, and delete these lines…: ```csharp if (parents == null) { parents = Enumerable.Empty(); } parents = parents.Append(target); ``` …and lastly replace the remaining references to **parents** with **visitedSet**. There should be two **parents.Contains()** calls and two recursive calls to **GetGenericUpdateTasks()** (the same ones you added **depth + 1** to earlier). ### Fixing issue 3 Find the **SearchGameObject** method, and copy/paste this into the first foreach in it: ```csharp // If this component is part of a prefab instance in a scene, skip it unless // it actually has overrides. The source prefab asset will be scanned separately. if (PrefabUtility.IsPartOfPrefabInstance(behaviour)) { UnityEngine.Object source = PrefabUtility.GetCorrespondingObjectFromSource(behaviour); PropertyModification[] modifications = PrefabUtility.GetPropertyModifications(behaviour); bool hasOverrides = modifications != null && modifications.Any(m => m.target == source); if (!hasOverrides) continue; } ``` TADAAAA! It works, and is super-fast! Spend the saved time enjoying life with your family and being good to yourself. Best regards, Ultroman the Tacoman --- _[View the full topic](https://qa.fmod.com/t/unity-fmod-reference-updater-takes-15minutes-to-scan/22119)._