Thread.Sleep(2500) vs. Task.Delay(2500).Wait()

Question

I want some clarity on this. I know that Task.Delay will internally use a Timer and it is obviously task-based (awaitable), whereas Thread.Sleep will cause the thread to be blocked. However, does calling .Wait on the task cause the thread to be blocked?

If not, one would assume that Task.Delay(2500).Wait() is better than Thread.Sleep(2500). This is slightly different that the SO question/answer here as I'm calling .Wait().

Yes, `.Wait()` on a `Task` is a blocking call. From your perspective, they would essentially be equivalent. — Glorin Oakenfoot, Dec 02 '15 at 20:36
With such similar functionality offered by your 2 options, I think you really need to clarify what you mean by "better". — Simon MᶜKenzie, Dec 02 '15 at 20:42
Does this answer your question? [When to use Task.Delay, when to use Thread.Sleep?](https://stackoverflow.com/questions/20082221/when-to-use-task-delay-when-to-use-thread-sleep) — T.Todua, Jun 24 '22 at 15:47

i3arnon · Accepted Answer · 2015-12-02T20:41:10.680

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Using Wait on an uncompleted task is indeed blocking the thread until the task completes.

Using Thread.Sleep is clearer since you're explicitly blocking a thread instead of implicitly blocking on a task.

The only way using Task.Delay is preferable is that it allows using a CancellationToken so you can cancel the block if you like to.

edited Dec 02 '15 at 20:41

answered Dec 02 '15 at 20:38

i3arnon

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...But only if you have another thread running that can use the `CancellationToken` as the main thread will be blocked. – Bradley Uffner Dec 02 '15 at 20:39
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@BradleyUffner well, you can create a self cancelling token (using a timer internally)... – i3arnon Dec 02 '15 at 20:41

score 7 · Answer 2 · answered Dec 02 '15 at 20:40

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Thread.Sleep(...) creates an event to wake you up in X millisec, then puts your Thread to sleep... in X millisec, the event wakes you up.

Task.Delay(...).Wait() creates an event to start a Task in X millisec, then puts your Thread to sleep until the Task is done (with Wait)... in X millisec, the event starts the Task which ends immediately and then wakes you up.

Basically, they are both very similar. The only difference is if you want to wake up early from another Thread, you won't hit the same method.

answered Dec 02 '15 at 20:40

Guillaume F.

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"Task.Delay(...).Wait() creates an event to start a Task in X millisec, then puts your Thread to sleep until the Task is done" There's no task being created here. – Voo Dec 03 '15 at 08:32
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Yes there is one, but it's empty. Delay returns a Task object. – Guillaume F. Dec 03 '15 at 12:29
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Yeah badly formulated. No task is ever *started*. There's just a task object which is created by the TaskCompletionSource and whose state is updated after a while. – Voo Dec 03 '15 at 14:02

Thread.Sleep(2500) vs. Task.Delay(2500).Wait()

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