C# - Performance Issues with Large Object in Concurrent Dictionary with Custom Equality Comparer
I'm having a hard time understanding I'm working through a tutorial and I tried several approaches but none seem to work. I'm experiencing significant performance degradation when using a `ConcurrentDictionary<TKey, TValue>` with a large number of entries, particularly when using a custom equality comparer for the key type. The dictionary is supposed to handle concurrent access efficiently, but I noticed that the lookup times increase drastically when the number of entries exceeds a certain threshold (around 10,000). My key type is a complex object, and I implemented `IEqualityComparer<T>` to provide custom comparison logic. Here's a snippet of my custom comparer: ```csharp public class MyCustomComparer : IEqualityComparer<MyKeyType> { public bool Equals(MyKeyType x, MyKeyType y) { return x.Id == y.Id && x.Name == y.Name; } public int GetHashCode(MyKeyType obj) { unchecked { int hash = 17; hash = hash * 23 + obj.Id.GetHashCode(); hash = hash * 23 + (obj.Name?.GetHashCode() ?? 0); return hash; } } } ``` I am using .NET 5.0 and have set up the `ConcurrentDictionary` like this: ```csharp var myDictionary = new ConcurrentDictionary<MyKeyType, MyValueType>(new MyCustomComparer()); ``` When I perform bulk additions and then attempt to retrieve values using keys that were recently added, the operations take much longer than expected. The average time for a lookup seems to increase significantly, and I even noticed some intermittent timeout exceptions in my application logs. I've tried optimizing the `GetHashCode` implementation, ensuring that it produces unique values efficiently, but it didn't resolve the issue. Additionally, I verified that there are no locks or other threading issues elsewhere in my code. What could be causing this performance drop, and are there recommended best practices for using `ConcurrentDictionary` with complex key types? Any insights on how to mitigate this issue would be greatly appreciated! Cheers for any assistance! Any ideas what could be causing this?