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csharp-async · C# 异步编程最佳实践审查

提供 C# 异步编程规范,包括命名、返回类型、异常处理、性能与常见陷阱,并据此审查代码给出改进建议。

先看看示例

作者提供的示例,实际效果取决于你的输入和使用工具。

输入

审查一段使用 .Result 的异步方法,指出阻塞风险,建议改为 await 并补充 Async 后缀与取消令牌。

输出

预期交付:按规范列出的问题清单与改进建议,涵盖命名、返回类型、异常传播与阻塞调用等。(编辑说明,非实际运行结果)

方法说明

---
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.