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.NET Development
Previous Versions
.NET Framework 2.0
System.Threading
Thread Class
Thread Methods
Sleep Method
 Sleep Method (Int32)
This page is specific to
Microsoft Visual Studio 2005/.NET Framework 2.0

Other versions are also available for the following:
.NET Framework Class Library
Thread.Sleep Method (Int32)

Suspends the current thread for a specified time.

Namespace: System.Threading
Assembly: mscorlib (in mscorlib.dll)

Visual Basic (Declaration)
Public Shared Sub Sleep ( _
    millisecondsTimeout As Integer _
)
Visual Basic (Usage)
Dim millisecondsTimeout As Integer

Thread.Sleep(millisecondsTimeout)
C#
public static void Sleep (
    int millisecondsTimeout
)
C++
public:
static void Sleep (
    int millisecondsTimeout
)
J#
public static void Sleep (
    int millisecondsTimeout
)
JScript
public static function Sleep (
    millisecondsTimeout : int
)

Parameters

millisecondsTimeout

The number of milliseconds for which the thread is blocked. Specify zero (0) to indicate that this thread should be suspended to allow other waiting threads to execute. Specify Infinite to block the thread indefinitely.

Exception typeCondition

ArgumentOutOfRangeException

The time-out value is negative and is not equal to Infinite.

The thread will not be scheduled for execution by the operating system for the amount of time specified. This method changes the state of the thread to include WaitSleepJoin.

This method does not perform standard COM and SendMessage pumping.

NoteNote

If you need to sleep on a thread that has STAThreadAttribute, but you want to perform standard COM and SendMessage pumping, consider using one of the overloads of the Join method that specifies a timeout interval.

The following code example demonstrates a sleeping thread.

Visual Basic
Imports Microsoft.VisualBasic
Imports System
Imports System.Threading

Public Class ApartmentTest

    <MTAThread> _
    Shared Sub Main()
    
        Dim newThread As Thread = New Thread(AddressOf ThreadMethod)
        newThread.SetApartmentState(ApartmentState.MTA)

        ' The following line is ignored since 
        ' ApartmentState can only be set once.
        newThread.SetApartmentState(ApartmentState.STA)

        Console.WriteLine("ThreadState: {0}, ApartmentState: {1}", _
            newThread.ThreadState, newThread.GetApartmentState())

        newThread.Start()

        ' Wait for newThread to start and go to sleep.
        Thread.Sleep(300)
        Try
            ' This causes an exception since newThread is sleeping.
            newThread.SetApartmentState(ApartmentState.STA)
        Catch stateException As ThreadStateException
            Console.WriteLine(vbCrLf & "{0} caught:" & vbCrLf & _
                "Thread is not In the Unstarted or Running state.", _
                stateException.GetType().Name)
            Console.WriteLine("ThreadState: {0}, ApartmentState: " & _
                "{1}", newThread.ThreadState, newThread.GetApartmentState())
        End Try

    End Sub

    Shared Sub ThreadMethod()
        Thread.Sleep(1000)
    End Sub

End Class
C#
using System;
using System.Threading;

class ApartmentTest
{
    static void Main()
    {
        Thread newThread = 
            new Thread(new ThreadStart(ThreadMethod));
        newThread.SetApartmentState(ApartmentState.MTA);

        // The following line is ignored since 
        // ApartmentState can only be set once.
        newThread.SetApartmentState(ApartmentState.STA);

        Console.WriteLine("ThreadState: {0}, ApartmentState: {1}", 
            newThread.ThreadState, newThread.ApartmentState);

        newThread.Start();

        // Wait for newThread to start and go to sleep.
        Thread.Sleep(300);
        try
        {
            // This causes an exception since newThread is sleeping.
            newThread.SetApartmentState(ApartmentState.STA);
        }
        catch(ThreadStateException stateException)
        {
            Console.WriteLine("\n{0} caught:\n" +
                "Thread is not in the Unstarted or Running state.", 
                stateException.GetType().Name);
            Console.WriteLine("ThreadState: {0}, ApartmentState: {1}",
                newThread.ThreadState, newThread.GetApartmentState());
        }
    }

    static void ThreadMethod()
    {
        Thread.Sleep(1000);
    }
}
C++
using namespace System;
using namespace System::Threading;
ref class ApartmentTest
{
public:
   static void ThreadMethod()
   {
      Thread::Sleep( 1000 );
   }

};

int main()
{
   Thread^ newThread = gcnew Thread( gcnew ThreadStart( &ApartmentTest::ThreadMethod ) );
   newThread->SetApartmentState(ApartmentState::MTA);
   
   // The following line is ignored since 
   // ApartmentState can only be set once.
   newThread->SetApartmentState(ApartmentState::STA);
   Console::WriteLine( "ThreadState: {0}, ApartmentState: {1}", newThread->ThreadState.ToString(), newThread->GetApartmentState().ToString() );
   newThread->Start();
   
   // Wait for newThread to start and go to sleep.
   Thread::Sleep( 300 );
   try
   {
      
      // This causes an exception since newThread is sleeping.
      newThread->SetApartmentState(ApartmentState::STA);
   }
   catch ( ThreadStateException^ stateException ) 
   {
      Console::WriteLine( "\n{0} caught:\n"
      "Thread is not in the Unstarted or Running state.", stateException->GetType()->Name );
      Console::WriteLine( "ThreadState: {0}, ApartmentState: {1}", newThread->ThreadState.ToString(), newThread->GetApartmentState().ToString() );
   }

}

J#
import System.*;
import System.Threading.*;
import System.Threading.Thread;    

class ApartmentTest
{
    public static void main(String[] args)
    {
        Thread newThread = new Thread(new ThreadStart(ThreadMethod));

        newThread.set_ApartmentState(ApartmentState.MTA);

        // The following line is ignored since 
        // ApartmentState can only be set once.
        newThread.set_ApartmentState(ApartmentState.STA);
        Console.WriteLine("ThreadState: {0}, ApartmentState: {1}",
                        newThread.get_ThreadState(),
                        newThread.get_ApartmentState());
        newThread.Start();

        // Wait for newThread to start and go to sleep.
        Thread.Sleep(300);
        try {
            // This causes an exception since newThread is sleeping.
            newThread.set_ApartmentState(ApartmentState.STA);
        }
        catch (ThreadStateException stateException) {
            Console.WriteLine("\n{0} caught:\n" + 
                "Thread is not in the Unstarted or Running state.", 
                stateException.GetType().get_Name());
            Console.WriteLine("ThreadState: {0}, ApartmentState: {1}",
                newThread.get_ThreadState(),newThread.get_ApartmentState());
        }
    } //main

    static void ThreadMethod()
    {
        Thread.Sleep(1000);
    } //ThreadMethod
} //ApartmentTest

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0
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Prefer Sleep(1) to Sleep(0) to allow other waiting threads to execute.      Peter Ritchie - MVP   |   Edit   |  

Sleep(0) only gives up the current thread's time-slice to a thread at equal priority and is ready to run. To force the scheduler to the next thread in the queue (regardless of priority) you have to force your thread into the queue (which Sleep(0) does not) which can be accomplished with Sleep(1).

See http://www.bluebytesoftware.com/blog/PermaLink,guid,1c013d42-c983-4102-9233-ca54b8f3d1a1.aspx

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