csharp-async-patterns

Async/await in C# enables non-blocking asynchronous operations by letting methods pause and resume. Use ConfigureAwait(false) in library code, propagate CancellationTokens through call chains, avoid async void except in event handlers, and always await Task results. This prevents deadlocks, resource leaks, and improves application responsiveness.

Cancellation in async code uses CancellationToken passed through method signatures and checked within async methods. Operations like Task.Delay and HttpClient respect the token natively. Propagate tokens explicitly from entry points downward, and throw OperationCanceledException when signaled. This ensures clean, coordinated shutdown of long-running async workflows.

ValueTask reduces heap allocations in performance-critical async code paths where operations frequently complete synchronously. Use it for high-frequency async methods that often return completed results. Regular Task remains better for most library code and complex async workflows where the allocation overhead is negligible.

Convert sync methods to async by marking them with async, replacing blocking calls with await equivalents, and adding CancellationToken parameters. Implement timeouts using CancellationTokenSource.CancelAfter or Task.WaitAsync. Wrap operations in try-catch to handle TaskCanceledException and other async exceptions robustly.

Avoid async void outside event handlers, omitting ConfigureAwait in libraries, and forgetting CancellationToken propagation. Never use Task.Result or Task.Wait on async methods—await instead. Use Task.WhenAll for parallel execution and sequential await for dependencies. These mistakes cause deadlocks, context issues, and unhandled exceptions.

Yes. Implement retries by wrapping await calls in loops with exponential backoff. Add timeouts using CancellationTokenSource, Task.Delay between attempts, or Task.WaitAsync. Combine CancellationToken propagation with exception handling to enforce timeouts and retry limits across network calls and I/O operations.