csharp-async-patterns

Task allocates heap memory for every async operation, while ValueTask is a struct that avoids allocation when the operation completes synchronously. Use ValueTask for hot paths and high-frequency operations to reduce garbage collection pressure; use Task for general-purpose asynchronous work.

Apply async/await patterns with proper method signatures (async Task or async ValueTask), use await to compose operations, handle cancellation tokens, and orchestrate parallel tasks with Task.WhenAll or Task.WhenAny. Avoid blocking calls like .Result and fire-and-forget patterns outside event handlers.

Async streams (IAsyncEnumerable) enable iteration over data that arrives asynchronously over time. Use them for processing paginated API responses, real-time event feeds, or large datasets that can't fit in memory at once, yielding results as they become available.

Pass CancellationToken parameters through your async call chain and check token.ThrowIfCancellationRequested() or token.IsCancellationRequested within long-running operations. Wire tokens from UI timeouts, user actions, or scope disposal to propagate cancellation cleanly across tasks.

Yes. Maintain consistent async method signatures, avoid blocking with .Result or .Wait(), use ConfigureAwait(false) in libraries to prevent UI thread deadlocks, and pass cancellation tokens down call chains. Keep fire-and-forget patterns confined to event handlers with proper exception logging.

Modern C# supports nullable async methods, async Main, records with async operations, and refined ValueTask handling. Apply these versions' improvements to simplify null-safety in async flows, enable top-level async entry points, and optimize allocations with ValueTask and structured concurrency patterns.