Thread.Sleep for less than 1 millisecond

Question

I want to call thread sleep with less than 1 millisecond. I read that neither thread.Sleep nor Windows-OS support that.

What's the solution for that?

For all those who wonder why I need this: I'm doing a stress test, and want to know how many messages my module can handle per second. So my code is:

 // Set the relative part of Second hat will be allocated for each message   //For example: 5 messages - every message will get 200 miliseconds   var quantum = 1000 / numOfMessages;   for (var i = 0; i < numOfMessages; i++)  {       _bus.Publish(new MyMessage());       if (rate != 0)            Thread.Sleep(quantum);  } 

I'll be glad to get your opinion on that.

Answer 1

You can't do this. A single sleep call will typically block for far longer than a millisecond (it's OS and system dependent, but in my experience, Thread.Sleep(1) tends to block for somewhere between 12-15ms).

Windows, in general, is not designed as a real-time operating system. This type of control is typically impossible to achieve on normal (desktop/server) versions of Windows.

The closest you can get is typically to spin and eat CPU cycles until you've achieved the wait time you want (measured with a high performance counter). This, however, is pretty awful - you'll eat up an entire CPU, and even then, you'll likely get preempted by the OS at times and effectively "sleep" for longer than 1ms...

Answer 2

The code below will most definitely offer a more precise way of blocking, rather than calling Thread.Sleep(x); (although this method will block the thread, not put it to sleep). Below we are using the StopWatch class to measure how long we need to keep looping and block the calling thread.

using System.Diagnostics;  private static void NOP(double durationSeconds) {     var durationTicks = Math.Round(durationSeconds * Stopwatch.Frequency);     var sw = Stopwatch.StartNew();      while (sw.ElapsedTicks < durationTicks)     {      } } 

Example usage,

private static void Main() {     NOP(5); // Wait 5 seconds.      Console.WriteLine("Hello World!");      Console.ReadLine(); }