C# - Difficulty with Scoped Services in ASP.NET Core and Dependency Injection Lifetimes
I'm working on a personal project and I'm facing an issue with dependency injection lifetimes in my ASP.NET Core application (version 6.0). I have a scoped service that depends on a singleton service, which I understand isn't recommended due to potential issues with shared state across requests. However, I'm trying to implement a caching mechanism where the singleton service is responsible for maintaining a cache, and the scoped service needs to access this cache. Here's a simplified version of my service setup: ```csharp public interface ICacheService { T Get<T>(string key); void Set<T>(string key, T value); } public class CacheService : ICacheService { private readonly Dictionary<string, object> _cache = new(); public T Get<T>(string key) { return _cache.TryGetValue(key, out var value) ? (T)value : default; } public void Set<T>(string key, T value) { _cache[key] = value; } } public class MyScopedService { private readonly ICacheService _cacheService; public MyScopedService(ICacheService cacheService) { _cacheService = cacheService; } public string GetData(string key) { var data = _cacheService.Get<string>(key); return data ?? "No data found"; } } ``` In my `Startup.cs`, I have: ```csharp public void ConfigureServices(IServiceCollection services) { services.AddSingleton<ICacheService, CacheService>(); services.AddScoped<MyScopedService>(); } ``` When I try to access `MyScopedService` from a controller, I sometimes get null values from the cache, especially under load. I suspect it might be a threading issue or related to how the services are being instantiated. I've also tried using `IAsyncDisposable` with no success. Is there an appropriate pattern or best practice I could be missing here? How can I ensure that the scoped service reliably accesses the singleton cache without racing conditions or data inconsistencies? My development environment is Ubuntu. Any ideas what could be causing this? Any ideas what could be causing this?