ThreadPool.GetMaxThreads(Int32, Int32) Methode

public:
 static void GetMaxThreads([Runtime::InteropServices::Out] int % workerThreads, [Runtime::InteropServices::Out] int % completionPortThreads);

public static void GetMaxThreads(out int workerThreads, out int completionPortThreads);

static member GetMaxThreads : int * int -> unit

Public Shared Sub GetMaxThreads (ByRef workerThreads As Integer, ByRef completionPortThreads As Integer)

Parameters

Voorbeelden

In het volgende codevoorbeeld ziet u hoe u het maximumaantal en het beschikbare aantal threads in de threadgroep ophaalt. Een werkitem wordt in de wachtrij geplaatst die wordt gebruikt FileStream om asynchroon naar twee bestanden te schrijven. De callback-methoden worden getimed om elkaar te overlappen. Een werkthread verwerkt het werkitem en, afhankelijk van de snelheid en het aantal processors op de computer, verwerken een of twee voltooiingspoortthreads de schrijfbewerkingen.

using System;
using System.IO;
using System.Security.Permissions;
using System.Threading;

class Test
{
    static void Main()
    {
        AutoResetEvent mainEvent = new AutoResetEvent(false);
        int workerThreads;
        int portThreads;

        ThreadPool.GetMaxThreads(out workerThreads, out portThreads);
        Console.WriteLine("\nMaximum worker threads: \t{0}" +
            "\nMaximum completion port threads: {1}",
            workerThreads, portThreads);

        ThreadPool.GetAvailableThreads(out workerThreads, 
            out portThreads);
        Console.WriteLine("\nAvailable worker threads: \t{0}" +
            "\nAvailable completion port threads: {1}\n",
            workerThreads, portThreads);

        ThreadPool.QueueUserWorkItem(new 
            WaitCallback(ThreadPoolTest.WorkItemMethod), mainEvent);
           
        // Since ThreadPool threads are background threads, 
        // wait for the work item to signal before ending Main.
        mainEvent.WaitOne(5000, false);
    }
}

class ThreadPoolTest
{
    // Maintains state information to be passed to EndWriteCallback.
    // This information allows the callback to end the asynchronous
    // write operation and signal when it is finished.
    class State
    {
        public FileStream     fStream;
        public AutoResetEvent autoEvent;

        public State(FileStream fStream, AutoResetEvent autoEvent)
        {
            this.fStream   = fStream;
            this.autoEvent = autoEvent;
        }
    }

    ThreadPoolTest() {}

    public static void WorkItemMethod(object mainEvent)
    {
        Console.WriteLine("\nStarting WorkItem.\n");
        AutoResetEvent autoEvent = new AutoResetEvent(false);

        // Create some data.
        const int ArraySize  = 10000;
        const int BufferSize =  1000;
        byte[] byteArray = new Byte[ArraySize];
        new Random().NextBytes(byteArray);

        // Create two files and two State objects. 
        FileStream fileWriter1 = 
            new FileStream(@"C:\Test1@##.dat", FileMode.Create, 
            FileAccess.ReadWrite, FileShare.ReadWrite, 
            BufferSize, true);
        FileStream fileWriter2 = 
            new FileStream(@"C:\Test2@##.dat", FileMode.Create, 
            FileAccess.ReadWrite, FileShare.ReadWrite, 
            BufferSize, true);
        State stateInfo1 = new State(fileWriter1, autoEvent);
        State stateInfo2 = new State(fileWriter2, autoEvent);

        // Asynchronously write to the files.
        fileWriter1.BeginWrite(byteArray, 0, byteArray.Length, 
            new AsyncCallback(EndWriteCallback), stateInfo1);
        fileWriter2.BeginWrite(byteArray, 0, byteArray.Length, 
            new AsyncCallback(EndWriteCallback), stateInfo2);

        // Wait for the callbacks to signal.
        autoEvent.WaitOne();
        autoEvent.WaitOne();

        fileWriter1.Close();
        fileWriter2.Close();
        Console.WriteLine("\nEnding WorkItem.\n");

        // Signal Main that the work item is finished.
        ((AutoResetEvent)mainEvent).Set();
    }

    static void EndWriteCallback(IAsyncResult asyncResult)
    {
        Console.WriteLine("Starting EndWriteCallback.");

        State stateInfo = (State)asyncResult.AsyncState;
        int workerThreads;
        int portThreads;
        try
        {
            ThreadPool.GetAvailableThreads(out workerThreads, 
                out portThreads);
            Console.WriteLine("\nAvailable worker threads: \t{0}" +
                "\nAvailable completion port threads: {1}\n",
                workerThreads, portThreads);

            stateInfo.fStream.EndWrite(asyncResult);

            // Sleep so the other thread has a chance to run
            // before the current thread ends.
            Thread.Sleep(1500);
        }
        finally
        {
            // Signal that the current thread is finished.
            stateInfo.autoEvent.Set();
            Console.WriteLine("Ending EndWriteCallback.");
        }
    }
}

Imports System.IO
Imports System.Security.Permissions
Imports System.Threading

Public Class Example
    Shared Sub Main()
        Dim mainEvent As New AutoResetEvent(False)
        Dim workerThreads As Integer 
        Dim portThreads As Integer 

        ThreadPool.GetMaxThreads(workerThreads, portThreads)
        Console.WriteLine(vbCrLf & "Maximum worker threads: " & _
            vbTab & "{0}" & vbCrLf & "Maximum completion port " & _
            "threads: {1}", workerThreads, portThreads)

        ThreadPool.GetAvailableThreads(workerThreads, portThreads)
        Console.WriteLine(vbCrLf & "Available worker threads: " & _
            vbTab & "{0}" & vbCrLf & "Available completion port " & _
            "threads: {1}" & vbCrLf, workerThreads, portThreads)

        ThreadPool.QueueUserWorkItem(AddressOf _
            ThreadPoolTest.WorkItemMethod, mainEvent)
           
        ' Since ThreadPool threads are background threads, 
        ' wait for the work item to signal before ending Main.
        mainEvent.WaitOne(5000, False)
    End Sub

End Class

Public Class ThreadPoolTest

    ' Maintains state information to be passed to EndWriteCallback.
    ' This information allows the callback to end the asynchronous
    ' write operation and signal when it is finished.
    Class State
        Public fStream As FileStream
        Public autoEvent As AutoResetEvent

        Public Sub New(aFileStream As FileStream, anEvent As AutoResetEvent)
            fStream   = aFileStream
            autoEvent = anEvent
        End Sub
    End Class   
    
    Private Sub New
    End Sub

    Shared Sub WorkItemMethod(mainEvent As Object)
    
        Console.WriteLine(vbCrLf & "Starting WorkItem." & vbCrLf)
        Dim autoEvent As New AutoResetEvent(False)

        ' Create some data.
        Const ArraySize As Integer  = 10000
        Const BufferSize As Integer =  1000
        Dim byteArray As Byte() = New Byte(ArraySize){}
        Dim randomGenerator As New Random()
        randomGenerator.NextBytes(byteArray)

        ' Create two files and two State objects. 
        Dim fileWriter1 As FileStream = _
            New FileStream("C:\Test1111.dat", FileMode.Create, _
            FileAccess.ReadWrite, FileShare.ReadWrite, _
            BufferSize, True)
        Dim fileWriter2 As FileStream = _
            New FileStream("C:\Test2222.dat", FileMode.Create, _
            FileAccess.ReadWrite, FileShare.ReadWrite, _
            BufferSize, True)
        Dim stateInfo1 As New State(fileWriter1, autoEvent)
        Dim stateInfo2 As New State(fileWriter2, autoEvent)

        ' Asynchronously write to the files.
        fileWriter1.BeginWrite(byteArray, 0, byteArray.Length, _
            AddressOf EndWriteCallback, stateInfo1)
        fileWriter2.BeginWrite(byteArray, 0, byteArray.Length, _
            AddressOf EndWriteCallback, stateInfo2)

        ' Wait for the callbacks to signal.
        autoEvent.WaitOne()
        autoEvent.WaitOne()

        fileWriter1.Close()
        fileWriter2.Close()
        Console.WriteLine(vbCrLf & "Ending WorkItem." & vbCrLf)

        ' Signal Main that the work item is finished.
        DirectCast(mainEvent, AutoResetEvent).Set()
    
    End Sub

    Shared Sub EndWriteCallback(asyncResult As IAsyncResult)
        Console.WriteLine("Starting EndWriteCallback.")

        Dim stateInfo As State = _
            DirectCast(asyncResult.AsyncState, State)
        Dim workerThreads As Integer 
        Dim portThreads As Integer 
        Try
            ThreadPool.GetAvailableThreads(workerThreads, portThreads)
            Console.WriteLine(vbCrLf & "Available worker " & _
                "threads:" & vbTab & "{0}" & vbCrLf & "Available " & _
                "completion port threads: {1}" & vbCrLf, _
                workerThreads, portThreads)

            stateInfo.fStream.EndWrite(asyncResult)

            ' Sleep so the other thread has a chance to run
            ' before the current thread ends.
            Thread.Sleep(1500)
        Finally
        
            ' Signal that the current thread is finished.
            stateInfo.autoEvent.Set()
            Console.WriteLine("Ending EndWriteCallback.")
        End Try
    
    End Sub
End Class

Opmerkingen

Wanneer GetMaxThreads de variabele wordt geretourneerd, bevat de variabele die is workerThreads opgegeven het maximum aantal werkrolthreads dat is toegestaan in de threadgroep en bevat de variabele die is opgegeven door completionPortThreads het maximum aantal asynchrone I/O-threads dat is toegestaan in de threadgroep.

U kunt de GetAvailableThreads methode gebruiken om op elk gewenst moment het werkelijke aantal threads in de threadgroep te bepalen.

U kunt het SetMaxThreads maximum aantal werkthreads en asynchrone I/O-threads in de threadgroep instellen.

U kunt zoveel aanvragen voor threadgroepen in de wachtrij plaatsen als het systeemgeheugen toestaat. Als er meer aanvragen zijn dan threads voor threadgroepen, blijven de extra aanvragen in de wachtrij totdat threads beschikbaar zijn.

Zie ook

• SetMinThreads(Int32, Int32)
• GetMinThreads(Int32, Int32)
• GetAvailableThreads(Int32, Int32)
• SetMaxThreads(Int32, Int32)