ThreadPriority Výčet

Definice

Určuje prioritu Threadplánování.Specifies the scheduling priority of a Thread.

public enum class ThreadPriority
[System.Runtime.InteropServices.ComVisible(true)]
[System.Serializable]
public enum ThreadPriority
type ThreadPriority = 
Public Enum ThreadPriority
Dědičnost
ThreadPriority
Atributy

Pole

AboveNormal 3

Může být naplánováno po vláknech Highest s Normal prioritou a před prioritami. ThreadThe Thread can be scheduled after threads with Highest priority and before those with Normal priority.

BelowNormal 1

Může být naplánováno po vláknech Normal s Lowest prioritou a před prioritami. ThreadThe Thread can be scheduled after threads with Normal priority and before those with Lowest priority.

Highest 4

Thread Může být naplánován před vlákny s jinou prioritou.The Thread can be scheduled before threads with any other priority.

Lowest 0

Thread Může být naplánováno po vláknech s jinou prioritou.The Thread can be scheduled after threads with any other priority.

Normal 2

Může být naplánováno po vláknech AboveNormal s BelowNormal prioritou a před prioritami. ThreadThe Thread can be scheduled after threads with AboveNormal priority and before those with BelowNormal priority. Ve výchozím Normal nastavení mají vlákna přednost.Threads have Normal priority by default.

Příklady

Následující příklad kódu ukazuje výsledek změny priority vlákna.The following code example shows the result of changing the priority of a thread. Vytvoří se tři vlákna, priorita jednoho vlákna je nastavená na BelowNormal a priorita druhé je nastavená na třídy priorit AboveNormal.Three threads are created, the priority of one thread is set to BelowNormal, and the priority of a second is set to AboveNormal. Každé vlákno zvýší proměnnou ve while smyčce a spustí se pro nastavený čas.Each thread increments a variable in a while loop and runs for a set time.

using System;
using System.Threading;
using Timers = System.Timers;

class Test
{
    static void Main()
    {
        PriorityTest priorityTest = new PriorityTest();

        Thread thread1 = new Thread(priorityTest.ThreadMethod);
        thread1.Name = "ThreadOne";
        Thread thread2 = new Thread(priorityTest.ThreadMethod);
        thread2.Name = "ThreadTwo";
        thread2.Priority = ThreadPriority.BelowNormal;
        Thread thread3 = new Thread(priorityTest.ThreadMethod);
        thread3.Name = "ThreadThree";
        thread3.Priority = ThreadPriority.AboveNormal;

        thread1.Start();
        thread2.Start();
        thread3.Start();
        // Allow counting for 10 seconds.
        Thread.Sleep(10000);
        priorityTest.LoopSwitch = false;
    }
}

class PriorityTest
{
    static bool loopSwitch;
    [ThreadStatic] static long threadCount = 0;

    public PriorityTest()
    {
        loopSwitch = true;
    }

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

    public void ThreadMethod()
    {
        while(loopSwitch)
        {
            threadCount++;
        }
        Console.WriteLine("{0,-11} with {1,11} priority " +
            "has a count = {2,13}", Thread.CurrentThread.Name, 
            Thread.CurrentThread.Priority.ToString(), 
            threadCount.ToString("N0")); 
    }
}
// The example displays output like the following:
//    ThreadOne   with      Normal priority has a count =   755,897,581
//    ThreadThree with AboveNormal priority has a count =   778,099,094
//    ThreadTwo   with BelowNormal priority has a count =     7,840,984
Imports System.Threading
Imports Timers = System.Timers

Public Module Example
   Dim t As Timers.Timer
   Private priorityTest As New PriorityTest()

    Public Sub Main()
        Dim thread1 As New Thread(AddressOf priorityTest.ThreadMethod)
        thread1.Name = "ThreadOne"
        Dim thread2 As New Thread(AddressOf priorityTest.ThreadMethod)
        thread2.Name = "ThreadTwo"
        thread2.Priority = ThreadPriority.BelowNormal
        Dim thread3 As New Thread(AddressOf priorityTest.ThreadMethod)
        thread3.Name = "ThreadThree"
        thread3.Priority = ThreadPriority.AboveNormal
        thread1.Start()
        thread2.Start()
        thread3.Start()

        ' Allow threads to execute for about 10 seconds.
        t = New Timers.Timer()
        t.AutoReset = False
        t.Interval = 10000
        AddHandler t.Elapsed, AddressOf Elapsed
        t.Start()
    End Sub

    Private Sub Elapsed(sender As Object, e As Timers.ElapsedEventArgs)
       priorityTest.LoopSwitch = False
    End Sub
End Module

Public Class PriorityTest
    Private Shared loopSwitchValue As Boolean
    <ThreadStatic> Shared threadCount As Long

    Sub New()
        loopSwitchValue = True
    End Sub

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

    Sub ThreadMethod()
        Do While True
            threadCount += 1
            If Not loopSwitchValue Then Exit Do
        Loop

        Console.WriteLine("{0,-11} with {1,11} priority " &
            "has a count = {2,13}", Thread.CurrentThread.Name,
            Thread.CurrentThread.Priority.ToString(),
            threadCount.ToString("N0")) 
    End Sub
End Class
' The example displays the following output:
'    ThreadOne   with      Normal priority has a count =   755,897,581
'    ThreadThree with AboveNormal priority has a count =   778,099,094
'    ThreadTwo   with BelowNormal priority has a count =     7,840,984

Poznámky

ThreadPrioritydefinuje sadu všech možných hodnot pro prioritu vlákna.ThreadPriority defines the set of all possible values for a thread priority. Priority vlákna určují relativní prioritu jednoho vlákna versus jiné.Thread priorities specify the relative priority of one thread versus another.

Každé vlákno má přiřazenou prioritu.Every thread has an assigned priority. K vláknům vytvořeným v modulu runtime se Normal zpočátku přiřadí priorita, zatímco vlákna vytvořená mimo modul runtime při vstupu do modulu runtime zachovají jejich předchozí prioritu.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. Můžete získat a nastavit prioritu vlákna přístupem k jeho Priority vlastnosti.You can get and set the priority of a thread by accessing its Priority property.

Vlákna mají naplánované spouštění na základě jejich priority.Threads are scheduled for execution based on their priority. Algoritmus plánování použitý k určení pořadí spuštění vlákna se v jednotlivých operačních systémech liší.The scheduling algorithm used to determine the order of thread execution varies with each operating system. Operační systém může také prioritu vlákna upravit dynamicky, protože fokus uživatelského rozhraní se přesouvá mezi popředí a pozadím.The operating system can also adjust the thread priority dynamically as the user interface's focus is moved between the foreground and the background.

Priorita vlákna nemá vliv na stav vlákna; stav vlákna musí být Running předtím, než ho operační systém může naplánovat.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.

Platí pro

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