ThreadPriority Enumeration
Assembly: mscorlib (in mscorlib.dll)
| Member name | Description | |
|---|---|---|
![]() | AboveNormal | The Thread can be scheduled after threads with Highest priority and before those with Normal priority. |
![]() | BelowNormal | The Thread can be scheduled after threads with Normal priority and before those with Lowest priority. |
![]() | Highest | The Thread can be scheduled before threads with any other priority. |
![]() | Lowest | The Thread can be scheduled after threads with any other priority. |
![]() | Normal | The Thread can be scheduled after threads with AboveNormal priority and before those with BelowNormal priority. Threads have Normal priority by default. |
ThreadPriority defines the set of all possible values for a thread priority. Thread priorities specify the relative priority of one thread versus another.
Every thread has an assigned priority. Threads created within the runtime are initially assigned the Normal priority, while threads created outside the runtime retain their previous priority when they enter the runtime. You can get and set the priority of a thread by accessing its Priority property.
Threads are scheduled for execution based on their priority. The scheduling algorithm used to determine the order of thread execution varies with each operating system. The operating system can also adjust the thread priority dynamically as the user interface's focus is moved between the foreground and the background.
The priority of a thread does not affect the thread's state; the state of the thread must be Running before the operating system can schedule it.
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.
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")); } }
import System.*;
import System.Threading.*;
import System.Threading.Thread;
class Test
{
public static void main(String[] args)
{
PriorityTest priorityTest = new PriorityTest();
ThreadStart startDelegate = new ThreadStart(priorityTest.ThreadMethod);
Thread threadOne = new Thread(startDelegate);
threadOne.set_Name("ThreadOne");
Thread threadTwo = new Thread(startDelegate);
threadTwo.set_Name("ThreadTwo");
threadTwo.set_Priority(ThreadPriority.BelowNormal);
threadOne.Start();
threadTwo.Start();
// Allow counting for 10 seconds.
Thread.Sleep(10000);
priorityTest.set_LoopSwitch(false);
} //main
} //Test
class PriorityTest
{
private boolean loopSwitch;
public PriorityTest()
{
loopSwitch = true;
} //PriorityTest
/** @property
*/
public void set_LoopSwitch(boolean value)
{
loopSwitch = value;
} //set_LoopSwitch
public void ThreadMethod()
{
long threadCount = 0;
while (loopSwitch) {
threadCount++;
}
Console.WriteLine("{0} with {1,11} priority " + "has a count = {2,13}",
Thread.get_CurrentThread().get_Name(),
Thread.get_CurrentThread().get_Priority().toString(),
((System.Int32)threadCount).ToString("N0"));
} //ThreadMethod
} //PriorityTest
Windows 98, Windows Server 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 Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.Reference
System.Threading NamespaceThread
Other Resources
Scheduling ThreadsManaged and Unmanaged Threading
