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

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Solution 1

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.

Solution 2

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.

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David Pine
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David Pine

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Updated on June 05, 2022

Comments

  • David Pine
    David Pine over 1 year

    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().

  • Bradley Uffner
    Bradley Uffner about 8 years
    ...But only if you have another thread running that can use the CancellationToken as the main thread will be blocked.
  • i3arnon
    i3arnon about 8 years
    @BradleyUffner well, you can create a self cancelling token (using a timer internally)...
  • Voo
    Voo about 8 years
    "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.
  • Guillaume F.
    Guillaume F. about 8 years
    Yes there is one, but it's empty. Delay returns a Task object.
  • Voo
    Voo about 8 years
    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.