How C# async/await Works: The State Machine and Continuations
await does not always wait: on a finished task the code continues on the same thread. What the async keyword actually does, the GetAwaiter/IsCompleted/OnCompleted steps, a working hand-written state machine, looking at the compiler-generated type with reflection (a class in Debug, a struct in Release), which thread runs the continuation, and the awaitable pattern.
7 Nov 2026
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10 min
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29
