Thread.ThreadState Property (System.Threading)

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.NET Framework Class Library

Thread.ThreadState Property

Gets a value containing the states of the current thread.

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

Syntax

Visual Basic

Public ReadOnly Property ThreadState As ThreadState

public ThreadState ThreadState { get; }

Visual C++

public:
property ThreadState ThreadState {
	ThreadState get ();
}

member ThreadState : ThreadState

Property Value

Type: System.Threading.ThreadState
One of the ThreadState values indicating the state of the current thread. The initial value is Unstarted.

Remarks

The ThreadState property provides more specific information than the IsAlive property.

Important
Thread state is only of interest in debugging scenarios. Your code should never use thread state to synchronize the activities of threads.

Examples

The following code example demonstrates accessing the ThreadState of a 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


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);
    }
}

Visual 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() );
   }

}

Version Information

.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Managed Thread States