Thread.IsBackground Property (System.Threading)

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.NET Framework Class Library

Thread.IsBackground Property

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Gets or sets a value indicating whether or not a thread is a background thread.

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

Syntax

Visual Basic


Public Property IsBackground As Boolean


public bool IsBackground { get; set; }

Visual C++


public:
property bool IsBackground {
	bool get ();
	void set (bool value);
}


member IsBackground : bool with get, set

Property Value

Type: System.Boolean
true if this thread is or is to become a background thread; otherwise, false.

Exceptions

Exception	Condition
ThreadStateException	The thread is dead.

Remarks

A thread is either a background thread or a foreground thread. Background threads are identical to foreground threads, except that background threads do not prevent a process from terminating. Once all foreground threads belonging to a process have terminated, the common language runtime ends the process. Any remaining background threads are stopped and do not complete.

Examples

The following code example contrasts the behavior of foreground and background threads. A foreground thread and a background thread are created. The foreground thread keeps the process running until it completes its while loop. After the foreground thread has finished, the process is terminated before the background thread has completed its while loop.

Visual Basic


Imports System
Imports System.Threading

Public Class Test

    <MTAThread> _
    Shared Sub Main()
        Dim shortTest As New BackgroundTest(10)
        Dim foregroundThread As New Thread(AddressOf shortTest.RunLoop)
        foregroundThread.Name = "ForegroundThread"

        Dim longTest As New BackgroundTest(50)
        Dim backgroundThread As New Thread(AddressOf longTest.RunLoop)
        backgroundThread.Name = "BackgroundThread"
        backgroundThread.IsBackground = True

        foregroundThread.Start()
        backgroundThread.Start()
    End Sub

End Class

Public Class BackgroundTest

    Dim maxIterations As Integer 

    Sub New(maximumIterations As Integer)
        maxIterations = maximumIterations
    End Sub

    Sub RunLoop()
        Dim threadName As String = Thread.CurrentThread.Name

        For i As Integer = 0 To maxIterations
            Console.WriteLine("{0} count: {1}", _
                    threadName, i.ToString())
            Thread.Sleep(250)
        Next i

        Console.WriteLine("{0} finished counting.", threadName)
    End Sub

End Class


using System;
using System.Threading;

class Test
{
    static void Main()
    {
        BackgroundTest shortTest = new BackgroundTest(10);
        Thread foregroundThread = 
            new Thread(new ThreadStart(shortTest.RunLoop));
        foregroundThread.Name = "ForegroundThread";

        BackgroundTest longTest = new BackgroundTest(50);
        Thread backgroundThread = 
            new Thread(new ThreadStart(longTest.RunLoop));
        backgroundThread.Name = "BackgroundThread";
        backgroundThread.IsBackground = true;

        foregroundThread.Start();
        backgroundThread.Start();
    }
}

class BackgroundTest
{
    int maxIterations;

    public BackgroundTest(int maxIterations)
    {
        this.maxIterations = maxIterations;
    }

    public void RunLoop()
    {
        String threadName = Thread.CurrentThread.Name;

        for(int i = 0; i < maxIterations; i++)
        {
            Console.WriteLine("{0} count: {1}", 
                threadName, i.ToString());
            Thread.Sleep(250);
        }
        Console.WriteLine("{0} finished counting.", threadName);
    }
}

Visual C++


using namespace System;
using namespace System::Threading;
ref class BackgroundTest
{
private:
   int maxIterations;

public:
   BackgroundTest( int maxIterations )
   {
      this->maxIterations = maxIterations;
   }

   void RunLoop()
   {
      String^ threadName = Thread::CurrentThread->Name;
      for ( int i = 0; i < maxIterations; i++ )
      {
         Console::WriteLine( "{0} count: {1}", threadName, i.ToString() );
         Thread::Sleep( 250 );

      }
      Console::WriteLine( "{0} finished counting.", threadName );
   }

};

int main()
{
   BackgroundTest^ shortTest = gcnew BackgroundTest( 10 );
   Thread^ foregroundThread = gcnew Thread( gcnew ThreadStart( shortTest, &BackgroundTest::RunLoop ) );
   foregroundThread->Name =  "ForegroundThread";
   BackgroundTest^ longTest = gcnew BackgroundTest( 50 );
   Thread^ backgroundThread = gcnew Thread( gcnew ThreadStart( longTest, &BackgroundTest::RunLoop ) );
   backgroundThread->Name =  "BackgroundThread";
   backgroundThread->IsBackground = true;
   foregroundThread->Start();
   backgroundThread->Start();
}

Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Platforms

Windows 8 Release Preview, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 SP2, Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

Reference

Thread Class

System.Threading Namespace

Other Resources

Foreground and Background Threads