In .NET Core, understanding when to use Transient, Scoped, and Singleton service lifetimes is crucial for efficient dependency management and application performance. Here’s a detailed explanation of each service lifetime and when to use them:
Transient Services
Definition: Transient services are created each time they are requested from the service container. This means a new instance of the service is created every time it is injected or requested.
Use Cases:
Stateless Services: Transient services are ideal for lightweight, stateless services where each operation requires a clean and independent instance. For example, services that perform simple calculations or generate random numbers.
Short-lived Operations: Use transient services for operations that do not need to maintain any state between different requests or operations.
Example:
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services.AddTransient<IMyService, MyService>();
In this example, IMyService will be instantiated anew each time it is requested.
Scoped Services
Definition: Scoped services are created once per request. In a web application, this means a new instance is created for each HTTP request but is shared across that request.
Use Cases:
Request-specific Data: Scoped services are useful when you need to maintain state within a single request. For example, database contexts (like Entity Framework DbContext) are often registered as scoped because they need to maintain state and track changes within a single request.
Shared Data within a Request: Use scoped services when multiple components within the same request need to share data or communicate.
Example:
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services.AddScoped<IMyService, MyService>();
In this example, IMyService will be instantiated once per HTTP request and shared within that request.
Singleton Services
Definition: Singleton services are created the first time they are requested and then reused for every subsequent request throughout the application's lifetime.
Use Cases:
Shared State: Singleton services are ideal for services that need to maintain state across the entire application, such as caching services, configuration settings, or logging services.
Expensive Initialization: Use singleton services for objects that are expensive to create and should not be recr...
