I know that Thread.Sleep
blocks a thread.
But does Task.Delay
also block? Or is it just like Timer
which uses one thread for all callbacks (when not overlapping)?
(this question doesn't cover the differences)
The documentation on MSDN is disappointing, but decompiling Task.Delay
using Reflector gives more information:
public static Task Delay(int millisecondsDelay, CancellationToken cancellationToken)
{
if (millisecondsDelay < -1)
{
throw new ArgumentOutOfRangeException("millisecondsDelay", Environment.GetResourceString("Task_Delay_InvalidMillisecondsDelay"));
}
if (cancellationToken.IsCancellationRequested)
{
return FromCancellation(cancellationToken);
}
if (millisecondsDelay == 0)
{
return CompletedTask;
}
DelayPromise state = new DelayPromise(cancellationToken);
if (cancellationToken.CanBeCanceled)
{
state.Registration = cancellationToken.InternalRegisterWithoutEC(delegate (object state) {
((DelayPromise) state).Complete();
}, state);
}
if (millisecondsDelay != -1)
{
state.Timer = new Timer(delegate (object state) {
((DelayPromise) state).Complete();
}, state, millisecondsDelay, -1);
state.Timer.KeepRootedWhileScheduled();
}
return state;
}
Basically, this method is just a timer wrapped inside of a task. So yes, you can say it's just like timer.