performance: reduce LINQ allocations in UpdateInstanceControllers#2811
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performance: reduce LINQ allocations in UpdateInstanceControllers#2811
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Replace LINQ-heavy hot paths in InstanceProcessor that were executing every tick with zero-allocation equivalents. Changes: - Add a static `_activeIdScratch` HashSet reused across calls to CleanupOrphanedControllers, replacing the LINQ .Except().ToArray() chain that allocated on every invocation. - Change CleanupOrphanedControllers signature from IEnumerable<Guid> to MapInstance[] so the caller's already-available array is used directly, avoiding the intermediate .Select(map => map.MapInstanceId) projection. - Replaces GroupBy().ToDictionary().ToArray() in UpdateInstanceControllers with a manual Dictionary<Guid, List<MapInstance>> build loop, removing three allocating LINQ operators from the 250 ms update path. - Use lazy-init (toRemove ??= new List<Guid>()) so the removal list is only allocated when at least one orphaned controller is actually found. - Mark InstanceControllers as readonly to prevent accidental reassignment. No behaviour changes; purely allocation and GC pressure reduction. Signed-off-by: Arufonsu <17498701+Arufonsu@users.noreply.github.com>
Arufonsu
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pandinocoder
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Feb 22, 2026
| .GroupBy(m => m.MapInstanceId) | ||
| .ToDictionary(m => m.Key, m => m.ToArray()); | ||
| // Manual grouping + ToDictionary allocations | ||
| var mapsAndInstances = new Dictionary<Guid, List<MapInstance>>(); |
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Prefer CollectionType name = []; syntax when available
| var map = activeMaps[i]; | ||
| if (!mapsAndInstances.TryGetValue(map.MapInstanceId, out var list)) | ||
| { | ||
| mapsAndInstances[map.MapInstanceId] = list = new List<MapInstance>(); |
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Prefer collectionName = []; syntax when available
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| if (!ActiveIdScratch.Contains(id)) | ||
| { | ||
| (toRemove ??= new List<Guid>()).Add(id); |
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Prefer = []
Separate the assignment and .Add() into separate lines
| } | ||
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| List<Guid>? toRemove = null; | ||
| foreach (var id in InstanceControllers.Keys) |
| .Except(activeInstanceIds) | ||
| .Except(new Guid[1] { default }) // Never cleanup the overworld instance | ||
| .ToArray(); | ||
| ActiveIdScratch.Clear(); |
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The Clear() would most likely end up destroying the backing buffer, I'm not sure there's a point in a static variable for this.
| foreach (var id in toRemove) | ||
| { | ||
| InstanceControllers.Remove(id); | ||
| ApplicationContext.Context.Value?.Logger.LogDebug($"Removing instance controller {id}"); |
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I don't remember anymore what the correct code is but ApplicationContext.Context.Value?.Logger should be able to be shortened to something, maybe ApplicationContext.CurrentContext.Logger? This should be present elsewhere in the repo as well.
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Replace LINQ-heavy calls in InstanceProcessor that were executing every tick with zero-allocation equivalents.
Changes:
_activeIdScratchHashSet reused across calls to CleanupOrphanedControllers, replacing the LINQ .Except().ToArray() chain that allocated on every invocation.No behaviour changes; purely allocation and GC pressure reduction.