Sleep. This C# method pauses programs. It receives a value indicating the number of milliseconds to wait. It sometimes helps with diagnosing a problem.
Calling Sleep can be useful for waiting on an external application or task. It does not cause CPU usage during the pause. SpinWait, meanwhile, does cause CPU usage.
An example. Sleep is found on the Thread class. It is a static method that receives one parameter. You must either include System.Threading or call System.Threading.Thread.Sleep.
Tip You do not need to create a new Thread to use the Sleep method as it is static.
using System;
using System.Diagnostics;
using System.Threading;
//// Demonstrates 3 different ways of calling Sleep.//
var stopwatch = Stopwatch.StartNew();
Thread.Sleep(0);
stopwatch.Stop();
Console.WriteLine(stopwatch.ElapsedMilliseconds);
Console.WriteLine(DateTime.Now.ToLongTimeString());
stopwatch = Stopwatch.StartNew();
Thread.Sleep(5000);
stopwatch.Stop();
Console.WriteLine(stopwatch.ElapsedMilliseconds);
Console.WriteLine(DateTime.Now.ToLongTimeString());
stopwatch = Stopwatch.StartNew();
System.Threading.Thread.Sleep(1000);
stopwatch.Stop();
Console.WriteLine(stopwatch.ElapsedMilliseconds);
//// Bonus: shows SpinWait method.//
stopwatch = Stopwatch.StartNew();
Thread.SpinWait(100000 * 10000);
stopwatch.Stop();
Console.WriteLine(stopwatch.ElapsedMilliseconds);0
3:29:29 PM
5005
3:29:34 PM
1005
356
TimeSpan. We can also use Sleep() with a TimeSpan argument. To sleep for 3 seconds, for example, we can pass in a TimeSpan created with the TimeSpan.FromSeconds method.
Here The program pauses for 3 seconds when it is executed, then prints a message to the console before it terminates.
using System;
// Sleep for 3 seconds.
System.Threading.Thread.Sleep(TimeSpan.FromSeconds(3));
Console.WriteLine("[DONE]");[DONE]
Notes, usage. Suppose you have a program that modifies external files. You want to see how the files have been modified at a certain point.
So You can insert a call to Sleep(), and then manually check the files (while Sleep is suspending the program's operation).
SpinWait. When you execute the first program, you will notice that the program does not require significant CPU time when executing the Thread.Sleep calls.
Important The program only starts consuming the entire CPU core when the Thread.SpinWait method is invoked.
Info Sleep uses the operating system to "pause" the program, resulting in 0% CPU, while Thread.SpinWait executes useless instructions.
Summary. Thread.Sleep is fairly accurate in pausing the program for the specified number of milliseconds. Unlike SpinWait, Sleep does not cause your program to consume 100% CPU.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.
This page was last updated on Sep 11, 2023 (edit).