Thread.IsBackground Thread.IsBackground Thread.IsBackground Thread.IsBackground Property

Definition

Ruft einen Wert ab, der angibt, ob es sich bei einem Thread um einen Hintergrundthread handelt, oder legt diesen fest.Gets or sets a value indicating whether or not a thread is a background thread.

public:
 property bool IsBackground { bool get(); void set(bool value); };
public bool IsBackground { get; set; }
member this.IsBackground : bool with get, set
Public Property IsBackground As Boolean

Eigenschaftswert

true, wenn dieser Thread ein Hintergrundthread ist oder zu einem solchen wird, andernfalls false.true if this thread is or is to become a background thread; otherwise, false.

Ausnahmen

Beispiele

Im folgenden Beispiel wird das Verhalten von Vordergrund-und Hintergrundthreads gegenüberstellen.The following example contrasts the behavior of foreground and background threads. Er erstellt einen Vordergrund Thread und einen Hintergrund Thread.It creates a foreground thread and a background thread. Der Vordergrund Thread speichert den Prozess so lange, for bis die Schleife abgeschlossen ist und beendet wird.The foreground thread keeps the process running until completes its for loop and terminates. Wie die Ausgabe aus dem Beispiel zeigt, wird der Prozess beendet, bevor der Hintergrund Thread die Ausführung abgeschlossen hat, da der Vordergrund Thread die Ausführung abgeschlossen hat.However, as the output from the example shows, because the foreground thread has finished execution, the process is terminated before the background thread has completed execution.

using namespace System;
using namespace System::Threading;

ref class BackgroundTest
{
private:
   int maxIterations;

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

   void RunLoop()
   {
      for (int i = 0; i < maxIterations; i++ )
      {
         Console::WriteLine("{0} count: {1}", 
              Thread::CurrentThread->IsBackground ? 
              "Background Thread" : "Foreground Thread", i);
         Thread::Sleep(250);

      }
      Console::WriteLine("{0} finished counting.", 
                         Thread::CurrentThread->IsBackground ? 
                         "Background Thread" : "Foreground Thread");
   }
};

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();
}

using System;
using System.Threading;

class Example
{
    static void Main()
    {
        BackgroundTest shortTest = new BackgroundTest(10);
        Thread foregroundThread = 
            new Thread(new ThreadStart(shortTest.RunLoop));

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

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

class BackgroundTest
{
    int maxIterations;

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

    public void RunLoop()
    {
        for (int i = 0; i < maxIterations; i++) {
            Console.WriteLine("{0} count: {1}", 
                Thread.CurrentThread.IsBackground ? 
                   "Background Thread" : "Foreground Thread", i);
            Thread.Sleep(250);
        }
        Console.WriteLine("{0} finished counting.", 
                          Thread.CurrentThread.IsBackground ? 
                          "Background Thread" : "Foreground Thread");
    }
}
// The example displays output like the following:
//    Foreground Thread count: 0
//    Background Thread count: 0
//    Background Thread count: 1
//    Foreground Thread count: 1
//    Foreground Thread count: 2
//    Background Thread count: 2
//    Foreground Thread count: 3
//    Background Thread count: 3
//    Background Thread count: 4
//    Foreground Thread count: 4
//    Foreground Thread count: 5
//    Background Thread count: 5
//    Foreground Thread count: 6
//    Background Thread count: 6
//    Background Thread count: 7
//    Foreground Thread count: 7
//    Background Thread count: 8
//    Foreground Thread count: 8
//    Foreground Thread count: 9
//    Background Thread count: 9
//    Background Thread count: 10
//    Foreground Thread count: 10
//    Background Thread count: 11
//    Foreground Thread finished counting.
Imports System.Threading

Public Module Example
    Public Sub Main()
        Dim shortTest As New BackgroundTest(10)
        Dim foregroundThread As New Thread(AddressOf shortTest.RunLoop)

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

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

Public Class BackgroundTest
    Dim maxIterations As Integer 

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

    Sub RunLoop()
        For i As Integer = 0 To maxIterations
            Console.WriteLine("{0} count: {1}", _
                    If(Thread.CurrentThread.IsBackground, 
                       "Background Thread", "Foreground Thread"), i)
            Thread.Sleep(250)
        Next 

        Console.WriteLine("{0} finished counting.", 
                          If(Thread.CurrentThread.IsBackground, 
                          "Background Thread", "Foreground Thread"))
    End Sub
End Class
' The example displays output like the following:
'    Foreground Thread count: 0
'    Background Thread count: 0
'    Background Thread count: 1
'    Foreground Thread count: 1
'    Foreground Thread count: 2
'    Background Thread count: 2
'    Foreground Thread count: 3
'    Background Thread count: 3
'    Background Thread count: 4
'    Foreground Thread count: 4
'    Foreground Thread count: 5
'    Background Thread count: 5
'    Foreground Thread count: 6
'    Background Thread count: 6
'    Background Thread count: 7
'    Foreground Thread count: 7
'    Background Thread count: 8
'    Foreground Thread count: 8
'    Foreground Thread count: 9
'    Background Thread count: 9
'    Background Thread count: 10
'    Foreground Thread count: 10
'    Background Thread count: 11
'    Foreground Thread finished counting.

Hinweise

Ein Thread ist entweder ein Hintergrund Thread oder ein Vordergrund Thread.A thread is either a background thread or a foreground thread. Hintergrundthreads sind mit Vorder grundthreads identisch, mit der Ausnahme, dass Hintergrundthreads nicht verhindern, dass ein Prozess beendet wird.Background threads are identical to foreground threads, except that background threads do not prevent a process from terminating. Nachdem alle für einen Prozess gehörenden Vordergrundthreads beendet wurden, beendet der Common Language Runtime den Prozess.Once all foreground threads belonging to a process have terminated, the common language runtime ends the process. Alle verbleibenden Hintergrundthreads werden beendet und werden nicht beendet.Any remaining background threads are stopped and do not complete.

Standardmäßig werden die folgenden Threads im Vordergrund ausgeführt (d. h. IsBackground , Ihre false-Eigenschaft gibt zurück):By default, the following threads execute in the foreground (that is, their IsBackground property returns false):

  • Der primäre Thread (oder Hauptanwendungs Thread).The primary thread (or main application thread).

  • Alle Threads, die durch Aufrufen Thread eines Klassenkonstruktors erstellt wurden.All threads created by calling a Thread class constructor.

Standardmäßig werden die folgenden Threads im Hintergrund ausgeführt (d. h., IsBackground Ihre- trueEigenschaft gibt zurück):By default, the following threads execute in the background (that is, their IsBackground property returns true):

  • Thread Poolthreads, bei denen es sich um einen Pool von Arbeitsthreads handelt, die von der Laufzeit verwaltet werden.Thread pool threads, which are a pool of worker threads maintained by the runtime. Mithilfe der ThreadPool -Klasse können Sie den Thread Pool konfigurieren und arbeiten an Thread Pool-Threads planen.You can configure the thread pool and schedule work on thread pool threads by using the ThreadPool class.

    Hinweis

    Aufgabenbasierte asynchrone Vorgänge werden automatisch in Thread Pool-Threads ausgeführt.Task-based asynchronous operations automatically execute on thread pool threads.

  • Alle Threads, die aus nicht verwaltetem Code in die verwaltete Ausführungsumgebung eintreten.All threads that enter the managed execution environment from unmanaged code.

Gilt für:

Siehe auch