Time Delay in C#

Question

The following function System.Threading.Thread.Sleep(); delay the thread in millisecond, and take the integer value as a parameter. Is there any method of thread delay in microsecond. Or can sleep function take the float values? Thanks

Providing a meaningful answer to this question would be easier if you stated why you need to sleep for such short periods. Perhaps there is a different approach to accomplish what you need in a way that doesn't require any calls to Sleep(). — LBushkin, May 25 '09 at 03:43
[look at what I said in another question about stopwatch](http://stackoverflow.com/questions/1631501/need-microsecond-delay-in-net-app-for-throttling-udp-multicast-transmission-rate/1631542#1631542) — Fredou, Nov 04 '09 at 02:21

score 17 · Accepted Answer · edited May 23 '17 at 12:19

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Nope. To quote Will Dean from 85122

you can't meaningfully 'sleep' (i.e. relinquish your scheduled CPU) for such short periods. If you want to delay for some short time, then you need to spin, repeatedly checking a suitably high-resolution timer (e.g. the 'performance timer') and hoping that something of high priority doesn't pre-empt you anyway.

edited May 23 '17 at 12:19

Community

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answered May 24 '09 at 12:40

Dan F

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driis · Answer 2 · 2009-05-24T12:49:36.867

Sleep is not accurate to the millisecond in the first place. I think it's resolution is hardware dependent, and the smallest slice of time you can sleep will typically be around 20 ms. This has to do with Sleep actually releases what might be remaining of the current thread's timeslice; and allows another thread to run. The earliest time your thread will be able to run again, is after one thread scheduler timeslice has passed. Therefore the resolution is about 20 ms (assuming a timeslice on your system is 20 ms).

Since Windows is not a real-time OS; Sleep and other wait functions can never be fully deterministic.

Depending on your application, you could perhaps do a Sleep for the most of the time and then do a busy wait where timing is critical. Or rewrite the structure so that you measure time passed accurately (use System.Diagnostics.Stopwatch); but do not depend on being able to sleep for an accurate time period in the millisecond range.

The first answer in this thread on MSDN also explains it very nicely.

I always thought the granularity was ~55ms, i.e., 18 ticks/second. — D'Arcy Rittich, May 24 '09 at 12:52
This was in the good old DOS days (and maybe early Windows). 1,193,180 Hz / 2^16 — Daniel Brückner, May 24 '09 at 13:05

score 1 · Answer 3 · answered May 24 '09 at 12:38

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The best granularity you will find for Thread.Sleep is using the TimeSpan class. Unfortunately the smallest granularity it supports is milliseconds. There is no way to sleep in the microseconds range.

answered May 24 '09 at 12:38

JaredPar

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and even with Sleep() the least you can do is around 15 - 20 ms – Lucas May 24 '09 at 12:49
@Lucas, very true. Sleep is not a fine grained, sleep for exactly X timespan type of function. – JaredPar May 24 '09 at 12:57

score 1 · Answer 4 · answered May 24 '09 at 14:45

I had to write a music program where the notes had to start/stop at the correct duration, precisely, so I used the high-resolution timer in DirectX to do this, but, my application would also stay on top and hog the cpu, so it could keep checking for when to do the next action.

Since there is no way to know exactly when the OS will return control to your application, Thread.Sleep will be a very bad choice, and, as was mentioned, the smallest time increment can vary between 10 and 50ms, in my experience.

Time Delay in C#

4 Answers4