ThreadPriority ThreadPriority ThreadPriority ThreadPriority Enum

Definizione

Consente di specificare la priorità di pianificazione di un Thread.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
Ereditarietà
ThreadPriorityThreadPriorityThreadPriorityThreadPriority
Attributi

Campi

AboveNormal AboveNormal AboveNormal AboveNormal 3

Thread può essere pianificato dopo i thread la cui priorità è Highest e prima di quelli la cui priorità è Normal.The Thread can be scheduled after threads with Highest priority and before those with Normal priority.

BelowNormal BelowNormal BelowNormal BelowNormal 1

Thread può essere pianificato dopo i thread la cui priorità è Normal e prima di quelli la cui priorità è Lowest.The Thread can be scheduled after threads with Normal priority and before those with Lowest priority.

Highest Highest Highest Highest 4

Thread può essere pianificato prima dei thread con una qualsiasi priorità.The Thread can be scheduled before threads with any other priority.

Lowest Lowest Lowest Lowest 0

Thread può essere pianificato dopo i thread con una qualsiasi priorità.The Thread can be scheduled after threads with any other priority.

Normal Normal Normal Normal 2

Thread può essere pianificato dopo i thread la cui priorità è AboveNormal e prima di quelli la cui priorità è BelowNormal.The Thread can be scheduled after threads with AboveNormal priority and before those with BelowNormal priority. I thread presentano la priorità Normal per impostazione predefinita.Threads have Normal priority by default.

Esempi

Esempio di codice seguente mostra il risultato della modifica della priorità di un thread.The following code example shows the result of changing the priority of a thread. Vengono creati tre thread e la priorità di un thread viene impostata su BelowNormal la priorità di secondo è impostata su AboveNormal.Three threads are created, the priority of one thread is set to BelowNormal, and the priority of a second is set to AboveNormal. Ogni thread incrementa una variabile in un while ciclo e viene eseguito per un determinato periodo di tempo.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

Commenti

ThreadPriority definisce il set di tutti i valori possibili per una priorità di thread.ThreadPriority defines the set of all possible values for a thread priority. Priorità dei thread specificare la priorità relativa di un thread rispetto a un altro.Thread priorities specify the relative priority of one thread versus another.

Ogni thread è stata assegnata una priorità.Every thread has an assigned priority. Thread creati all'interno del runtime viene inizialmente assegnato la Normal priorità, mentre i thread creati esternamente al runtime conservano la priorità precedente durante l'immissione di runtime.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. È possibile ottenere e impostare la priorità di un thread per l'accesso ai relativi Priority proprietà.You can get and set the priority of a thread by accessing its Priority property.

L'esecuzione dei thread viene pianificata in base alla relativa priorità.Threads are scheduled for execution based on their priority. L'algoritmo di pianificazione usato per determinare l'ordine di esecuzione dei thread varia con ciascuna il sistema operativo.The scheduling algorithm used to determine the order of thread execution varies with each operating system. Il sistema operativo è inoltre possibile regolare la priorità del thread in modo dinamico come lo stato attivo dell'interfaccia utente viene spostato in primo piano e sfondo.The operating system can also adjust the thread priority dynamically as the user interface's focus is moved between the foreground and the background.

La priorità di un thread non interferisca con stato del thread; lo stato del thread deve essere Running affinché il sistema operativo è la pianificazione.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.

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