C# Async Programming Best Practices

csharp-async

Best practices guide for C# asynchronous programming patterns and pitfalls.

github/awesome-copilot·10.8Kinstalls39.7KstarsDocumentation

SKILL.md

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C# Async Programming Best Practices

Your goal is to help me follow best practices for asynchronous programming in C#.

Naming Conventions

Use the 'Async' suffix for all async methods
Match method names with their synchronous counterparts when applicable (e.g., GetDataAsync() for GetData())

Return Types

Return Task<T> when the method returns a value
Return Task when the method doesn't return a value
Consider ValueTask<T> for high-performance scenarios to reduce allocations
Avoid returning void for async methods except for event handlers

Exception Handling

Use try/catch blocks around await expressions
Avoid swallowing exceptions in async methods
Use ConfigureAwait(false) when appropriate to prevent deadlocks in library code
Propagate exceptions with Task.FromException() instead of throwing in async Task returning methods

Performance

Use Task.WhenAll() for parallel execution of multiple tasks
Use Task.WhenAny() for implementing timeouts or taking the first completed task
Avoid unnecessary async/await when simply passing through task results
Consider cancellation tokens for long-running operations

Common Pitfalls

Never use .Wait(), .Result, or .GetAwaiter().GetResult() in async code
Avoid mixing blocking and async code
Don't create async void methods (except for event handlers)
Always await Task-returning methods

Implementation Patterns

Implement the async command pattern for long-running operations
Use async streams (IAsyncEnumerable<T>) for processing sequences asynchronously
Consider the task-based asynchronous pattern (TAP) for public APIs

When reviewing my C# code, identify these issues and suggest improvements that follow these best practices.

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npx -y skills add https://github.com/github/awesome-copilot --skill csharp-async

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