What is the difference between a timeout and cancellation, and how would you use both in .NET?

Timeout vs cancellation in .NET

Distinguish timeouts from cancellation and explain how to combine them around external calls and request handling.

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TL;DR

A timeout is a policy that says an operation should not run longer than a certain amount of time. Cancellation is a signal that asks work to stop. In .NET, I often implement timeouts by using a CancellationTokenSource with a timeout or by configuring the dependency client directly. A user disconnecting and a dependency timeout are different reasons for stopping work, even if both use cancellation tokens.

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Timeout boundaries, cooperative cancellation, request cancellation, dependency protection, and workflow correctness.

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A timeout is a duration policy, while cancellation is the cooperative signal used to stop work that is no longer useful. Separating the reason for cancellation matters because a caller disconnect, dependency timeout, and host shutdown require different recovery and telemetry.
A timeout is a policy that says an operation should not run longer than a certain amount of time. Cancellation is a signal that asks work to stop. In .NET, I often implement timeouts by using a CancellationTokenSource with a timeout or by configuring the dependency client directly. A user disconnecting and a dependency timeout are different reasons for stopping work, even if both use cancellation tokens.
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For example, an API request might have a client cancellation token, while the payment provider call has its own 3-second timeout. If the user disconnects, I may stop read-only work. If the payment call times out, I need to treat the outcome as unknown and reconcile later. The trade-off is that aggressive timeouts improve responsiveness but can increase retries, duplicate work, and partial failure handling.

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Treating timeout and cancellation as the same business event.
Retrying timed-out side effects without idempotency.
Using no timeout on external dependencies.
Cancelling durable operations after commit boundaries.
Logging all cancellations as production errors.

What is the difference between a timeout and cancellation, and how would you use both in .NET?

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