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Thread.Priority Property

.NET Framework 1.1

Gets or sets a value indicating the scheduling priority of a thread.

[Visual Basic]
Public Property Priority As ThreadPriority
[C#]
public ThreadPriority Priority {get; set;}
[C++]
public: __property ThreadPriority get_Priority();
public: __property void set_Priority(ThreadPriority);
[JScript]
public function get Priority() : ThreadPriority;
public function set Priority(ThreadPriority);

Property Value

One of the ThreadPriority values. The default value is Normal.

Exceptions

Exception Type	Condition
ThreadStateException	The thread has reached a final state, such as Aborted.
ArgumentException	The value specified for a set operation is not a valid ThreadPriority value.

Remarks

A thread can be assigned any one of the following priority values:

Highest
AboveNormal
Normal
BelowNormal
Lowest

Operating systems are not required to honor the priority of a thread.

Example

[Visual Basic, C#, C++] The following code example shows the result of changing the priority of a thread. Two threads are created and the priority of one thread is set to BelowNormal. Both threads increment a variable in a while loop and run for a set time.

[Visual Basic] 
Option Explicit
Option Strict

Imports System
Imports System.Threading

Public Class Test

    Shared Sub Main()
        Dim priorityTest As New PriorityTest()

        Dim threadOne As Thread = _
            New Thread(AddressOf priorityTest.ThreadMethod)
        threadOne.Name = "ThreadOne"
        Dim threadTwo As Thread = _
            New Thread(AddressOf priorityTest.ThreadMethod)
        threadTwo.Name = "ThreadTwo"

        threadTwo.Priority = ThreadPriority.BelowNormal
        threadOne.Start()
        threadTwo.Start()

        ' Allow counting for 10 seconds.
        Thread.Sleep(10000)
        priorityTest.LoopSwitch = False
    End Sub

End Class

Public Class PriorityTest

    Dim loopSwitchValue As Boolean 

    Sub New()
        loopSwitchValue = True
    End Sub

    WriteOnly Property LoopSwitch As Boolean
        Set
            loopSwitchValue = Value
        End Set
    End Property

    Sub ThreadMethod()
        Dim threadCount As Long = 0

        While loopSwitchValue
            threadCount += 1
        End While
        
        Console.WriteLine("{0} with {1,11} priority " & _
            "has a count = {2,13}", Thread.CurrentThread.Name, _
            Thread.CurrentThread.Priority.ToString(), _
            threadCount.ToString("N0")) 
    End Sub

End Class

[C#] 
using System;
using System.Threading;

class Test
{
    static void Main()
    {
        PriorityTest priorityTest = new PriorityTest();
        ThreadStart startDelegate = 
            new ThreadStart(priorityTest.ThreadMethod);

        Thread threadOne = new Thread(startDelegate);
        threadOne.Name = "ThreadOne";
        Thread threadTwo = new Thread(startDelegate);
        threadTwo.Name = "ThreadTwo";

        threadTwo.Priority = ThreadPriority.BelowNormal;
        threadOne.Start();
        threadTwo.Start();

        // Allow counting for 10 seconds.
        Thread.Sleep(10000);
        priorityTest.LoopSwitch = false;
    }
}

class PriorityTest
{
    bool loopSwitch;

    public PriorityTest()
    {
        loopSwitch = true;
    }

    public bool LoopSwitch
    {
        set{ loopSwitch = value; }
    }

    public void ThreadMethod()
    {
        long threadCount = 0;

        while(loopSwitch)
        {
            threadCount++;
        }
        Console.WriteLine("{0} with {1,11} priority " +
            "has a count = {2,13}", Thread.CurrentThread.Name, 
            Thread.CurrentThread.Priority.ToString(), 
            threadCount.ToString("N0")); 
    }
}

[C++] 
#using <mscorlib.dll>
using namespace System;
using namespace System::Threading;

__gc class PriorityTest
{
    bool loopSwitch;

public:
    PriorityTest()
    {
        loopSwitch = true;
    }

    __property void set_LoopSwitch(bool value)
    {
        loopSwitch = value;
    }

    void ThreadMethod()
    {
        __int64 threadCount = 0;

        while(loopSwitch)
        {
            threadCount++;
        }
        Console::WriteLine(S"{0} with {1,11} priority "
            S"has a count = {2,13}", Thread::CurrentThread->Name, 
            __box(Thread::CurrentThread->Priority)->ToString(), 
            threadCount.ToString("N0")); 
    }
};

void main()
{
    PriorityTest* priorityTest = new PriorityTest();
    ThreadStart* startDelegate = 
        new ThreadStart(priorityTest, &PriorityTest::ThreadMethod);

    Thread* threadOne = new Thread(startDelegate);
    threadOne->Name = "ThreadOne";
    Thread* threadTwo = new Thread(startDelegate);
    threadTwo->Name = "ThreadTwo";

    threadTwo->Priority = ThreadPriority::BelowNormal;
    threadOne->Start();
    threadTwo->Start();

    // Allow counting for 10 seconds.
    Thread::Sleep(10000);
    priorityTest->LoopSwitch = false;
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button in the upper-left corner of the page.

Requirements