Avoiding common pitfalls with async/await - Stephen Cleary - NDC Copenhagen 2025

Value of the Information & Strength of the Argument

The talk provides valuable insights into async/await, offering clear explanations of common misconceptions and practical advice. The speaker’s expertise is evident, and he supports his points with examples and analogies. The argumentation is solid, as he systematically addresses conceptual mistakes and then moves to specific pitfalls. He also provides nuanced guidance, such as when it might be acceptable to ignore best practices. The inclusion of advanced topics like ValueTask and Channels adds depth. However, some parts are based on personal opinion and experience rather than empirical evidence, but this is typical for expert talks.

Scientific Rigor, Source Quality, Title Accuracy

The speaker demonstrates scientific rigor by explaining the underlying mechanics of async/await and referencing his own articles and resources. He mentions a blog post by ‘duality’ (likely a reference to Kyle Simpson) and a blog post by John Skeet on async, but does not provide direct URLs in the talk. The description includes links to NDC conferences, which are not directly related to the content. The title accurately reflects the content, focusing on common pitfalls. The talk is well-structured and technically accurate, though it does not cite formal research papers. The speaker’s credibility as a Microsoft MVP and top Stack Overflow answerer adds to the reliability.

The title accurately reflects the content, which focuses on common async/await mistakes and their solutions.

8/10

The speaker is a recognized expert (Microsoft MVP, top Stack Overflow answerer) and the content is technically accurate, though it is based on personal experience and best practices rather than formal research.

Markers derived by PSI from the transcript: the creator did not define chapters.

• 02:00Introduction and context: talk focuses on .NET async/await, speaker introduces himself.
• 05:00Explanation of async keyword: enables await and transforms method into state machine.
• 10:00Explanation of await keyword: awaits a task, captures context, and resumes asynchronously.
• 15:00Conceptual mistake: await does not mean run on thread pool; async vs parallel.
• 20:00Three conceptual models: asynchronous wait, type wrapper, state machine/callback.
• 25:00Task as an object: can be stored, composed, and used with other types.
• 30:00ValueTask rules: consume only once, never block on it.
• 35:00First big pitfall: avoid async void methods.
• 40:00Second big pitfall: blocking on async code (sync over async).
• 45:00Advanced topics: ValueTask and Channels, and when to ignore best practices.

• NDC Conferences — Conference organizer; not directly related to content.
• NDC Copenhagen — Conference organizer; not directly related to content.

• Async/await on Wikipedia — General concept of async/await.
• Task-based Asynchronous Pattern (TAP) in .NET — Official Microsoft documentation on TAP.