SoFunction
Updated on 2025-03-04

What is .NET Runtime and its main functions

What is .NET Runtime (.NET runtime)?

.NET RuntimeIt is the core component that runs .NET applications. It provides the underlying support required for application operation, such as memory management, type system, garbage collection, thread management, etc. All applications based on .NET platform (such as Core, WinForms, WPF, etc.) rely on support for .NET Runtime.

In modern .NET (such as .NET 5+), the runtime mainly includes the following parts:

  • CoreCLR: Mainly aimed at Windows, Linux and macOS, providing complete runtime features.
  • Mono: Lightweight runtime, mainly aimed at mobile devices (such as Android and iOS) and game development (such as Unity).
  • Libraries: Base Class Libraries (BCL), providing common functions for applications (such as file I/O, network operations, collection classes, etc.).

.NET Runtime's main features

Hosted code execution：

  • Execute code written in .NET-supported languages ​​(such as C#, F#,).
  • Convert IL (Intermediate Language) to machine code through the Just-In-Time (JIT) or AOT (Ahead-Of-Time) compiler.

Memory management：

  • Automatically manage memory allocations on the heap and stack.
  • Garbage Collector (GC) is responsible for cleaning up memory that is no longer used.

Type safety and code verification：

  • Ensure that unauthorized or unsafe code is not executed at runtime.

Exception handling：

  • Provide a unified exception capture and handling mechanism to ensure the robustness of the program.

Cross-platform support：

  • Provides an abstraction layer that supports running the same application on different operating systems.

Performance optimization：

  • Includes instant compilation (JIT), local code caching, and improved startup speed and performance through AOT compilation.

Components of .NET Runtime

1. CoreCLR

  • Provides JIT compilation, garbage collection, thread management and other runtime core features.
  • Mainly used for server and desktop applications for Windows, Linux and macOS.
  • Supports high-performance applications.

2. Mono

  • Lightweight running time, suitable for resource-constrained devices, such as mobile (Android/iOS).
  • Supports AOT compilation and reduces runtime dependencies.
  • Used in scenarios such as Unity engine.

3. Libraries

  • Basic Class Library (BCL), such as、。
  • Provides common functions, such as data structures, file operations, network communications, etc.

4. Host

  • includeand, responsible for loading the runtime and executing the application.
  • Start the program from the entry point, load the runtime, and initialize the application environment.

5. GC（Garbage Collector）

  • Manage the allocation and recycling of managed memory.
  • Optimize memory usage and performance through intergenerational recycling strategies.

Runtime version

  • 1. .NET FrameworkThe earliest runtimes only supported Windows. Includes Common Language Runtime (CLR).
  • 2. .NET Core / .NETCross-platform runtime, including CoreCLR and Libraries. Starting from .NET 5, .NET Core and Mono have been unified to form a single runtime.
  • 3. MonoRun independently, supports mobile and embedded devices.
  • 4. NativeAOTProvides a mode of early compilation to compile the application directly into native code.
  • Not dependent on a full runtime.

Runtime workflow

Loader：

  • passdotnetCommands or other portals to load the application.
  • initializationhostfxrand runtime environment.

Loading assembly：

  • Read.dllIL code and metadata in the file.

JIT or AOT compilation：

  • Convert the IL to machine code for execution by the CPU.

Execute code：

  • Execute managed code to provide necessary runtime support.

Memory management：

  • Dynamically allocate and free memory to ensure efficient operation of applications.

How to install and use .NET Runtime

Install：

  • Automatically install runtime via the .NET SDK.
  • Download the runtime-only version directly (such as a server used in a production environment).

Run the program：

  • usedotnet runExecute managed code.
  • Or run the compiled program directly (such asor）。

Relationship with other components

  • Roslyn: Used to compile source code into IL code for runtime execution.
  • MSBuild: Generate the build tool for the program and run the build scripts at runtime.
  • Core: Rely on the managed environment and library support provided by the runtime.
  • Visual Studio: Calls MSBuild and runtime, supporting code debugging and execution.

Custom runtime

  • You can modify it based on the official .NET Runtime (CoreCLR or Mono) source code.
  • Compilation method:
git clone /dotnet/runtime
./ clr+libs

Custom runtimes can be used in special scenarios such as embedded devices.

Frequently Asked Questions

Is it necessary to install the runtime?

  • The development environment usually includes a runtime (provided through the SDK).
  • The self-contained deployment can be packaged during deployment.

How to choose a runtime?

  • Use .NET CoreCLR or Mono to select the runtime based on the target platform and performance requirements.

.NET Runtime is the core of managed code execution, supports cross-platform development, and provides high performance and flexibility, suitable for a variety of development scenarios.

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