/csharp-async

name: csharp-async
description: 'Get best practices for C# async programming'

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.