C# Beginners #23: Async Best Practices - ValueTask, CancellationToken, and the Mistakes That Bite
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Video Description
You know async and await. Now let's talk about what separates beginner async code from production-ready async code. ValueTask, CancellationToken, ConfigureAwait, and the mistakes that bite even experienced developers.
What you'll learn: • Why Task allocations matter on hot paths • ValueTask - struct vs class, zero allocation sync paths • When to use Task (default) vs ValueTask (hot paths) • The ValueTask rules you must follow • CancellationToken - accepting, passing, checking • HttpContext.RequestAborted in ASP.NET Core • Handling OperationCanceledException properly • ConfigureAwait(false) - when and why • Libraries vs application code guidance • Fire-and-forget anti-pattern exposed • Why discarding Tasks with _ is dangerous • Async over sync - don't fake it • Do/Don't reference table
Key insights: • Task is the default - use it unless you have a hot sync path • ValueTask can only be awaited once - don't store and reuse • Pass CancellationToken through your entire call chain • ConfigureAwait(false) is for library authors, not app code • Fire-and-forget without a background job system = lost exceptions • Don't wrap sync code in Task.Run to look async • Let the caller decide when to use Task.Run
Common mistakes we'll avoid: • Using ValueTask everywhere (it has rules!) • Ignoring cancellation requests • Using ConfigureAwait(false) in ASP.NET Core apps • Calling .Result or .Wait() on tasks • Fire-and-forget without proper infrastructure
Previous Video: Async/Await Basics Next Video: Parallel Programming ► Full Playlist: https://www.youtube.com/playlist?list=PLGxFXI4dC2shfDgudNdh1FtSLcAZG0-Ba ► Code Repository: https://github.com/benday-inc/csharp-for-beginners-2025
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#CSharp #AsyncAwait #ValueTask #CancellationToken #DotNet #Programming #BestPractices #CodingTutorial
0:00 Async Best Practices 0:16 What We're Covering 0:34 The Problem with Task Allocations 0:50 Enter ValueTask 1:14 Task vs ValueTask: When to Use Which 2:01 ValueTask Rules 2:31 CancellationToken: Why You Need It 2:46 Using CancellationToken 3:21 Handling Cancellation 3:43 ConfigureAwait: The Library Author's Friend 4:15 ConfigureAwait in Practice 4:57 Common Mistake: Fire and Forget 5:21 Fire and Forget: What Not to Do 5:42 Common Mistake: Async Over Sync 6:16 Best Practices Summary 6:45 Key Takeaways 7:20 Thanks for Watching
Video Info
- Duration: 7:25
- Published: January 14, 2026
