ThreadPool.GetAvailableThreads メソッド
アセンブリ: mscorlib (mscorlib.dll 内)

Public Shared Sub GetAvailableThreads ( _ <OutAttribute> ByRef workerThreads As Integer, _ <OutAttribute> ByRef completionPortThreads As Integer _ )
Dim workerThreads As Integer Dim completionPortThreads As Integer ThreadPool.GetAvailableThreads(workerThreads, completionPortThreads)
public: static void GetAvailableThreads ( [OutAttribute] int% workerThreads, [OutAttribute] int% completionPortThreads )
public static void GetAvailableThreads ( /** @attribute OutAttribute() */ /** @ref */ int workerThreads, /** @attribute OutAttribute() */ /** @ref */ int completionPortThreads )

GetAvailableThreads を呼び出すと、workerThreads に指定した変数には、追加で開始できるワーカー スレッドの数が格納され、completionPortThreads に指定した変数には、追加で開始できる非同期 I/O スレッドの数が格納されます。
使用できるスレッドがない場合、追加のスレッド プールの要求は、スレッド プール スレッドが使用可能になるまで、キューに置かれたままとなります。

スレッド プール内の最大スレッド数と使用できるスレッド数のカウントを取得する方法の例を次に示します。この例では、FileStream を使用して 2 つのファイルに非同期的に書き込みを行うための作業項目がキューに置かれます。また、コールバック メソッドは、オーバーラップするように時間設定されます。作業項目はワーカー スレッドによって処理され、コンピュータ上のプロセッサの速度と数に応じて、1 つまたは 2 つの完了ポート スレッドが書き込み操作を処理します。
Imports Microsoft.VisualBasic Imports System Imports System.IO Imports System.Security.Permissions Imports System.Threading ' Request permission to create two data files. <Assembly: FileIOPermissionAttribute(SecurityAction.RequestMinimum, _ All := "C:\Test1111.dat")> <Assembly: FileIOPermissionAttribute(SecurityAction.RequestMinimum, _ All := "C:\Test2222.dat")> Public Class Test <MTAThread> _ 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
using System; using System.IO; using System.Security.Permissions; using System.Threading; // Request permission to create two data files. [assembly: FileIOPermissionAttribute(SecurityAction.RequestMinimum, All = @"C:\Test1@##.dat")] [assembly: FileIOPermissionAttribute(SecurityAction.RequestMinimum, All = @"C:\Test2@##.dat")] 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."); } } }
using namespace System; using namespace System::IO; using namespace System::Security::Permissions; using namespace System::Threading; // Request permission to create two data files. [assembly:FileIOPermissionAttribute(SecurityAction::RequestMinimum, All="C:\\Test1#@@.dat")]; [assembly:FileIOPermissionAttribute(SecurityAction::RequestMinimum, All="C:\\Test2#@@.dat")]; ref class ThreadPoolTest { private: // 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. ref class State { public: FileStream^ fStream; AutoResetEvent^ autoEvent; State( FileStream^ fStream, AutoResetEvent^ autoEvent ) { this->fStream = fStream; this->autoEvent = autoEvent; } }; public: ThreadPoolTest(){} static void EndWriteCallback( IAsyncResult^ asyncResult ) { Console::WriteLine( "Starting EndWriteCallback." ); State^ stateInfo = dynamic_cast<State^>(asyncResult->AsyncState); int workerThreads; int portThreads; try { ThreadPool::GetAvailableThreads( workerThreads, portThreads ); Console::WriteLine( "\nAvailable worker threads: \t{0}" "\nAvailable completion port threads: {1}\n", workerThreads.ToString(), portThreads.ToString() ); stateInfo->fStream->EndWrite( asyncResult ); // Sleep so the other thread has a chance to run // before the current thread ends. Thread::Sleep( 1500 ); } catch ( Exception^ e ) { } finally { // Signal that the current thread is finished. stateInfo->autoEvent->Set(); Console::WriteLine( "Ending EndWriteCallback." ); } } static void WorkItemMethod( Object^ mainEvent ) { Console::WriteLine( "\nStarting WorkItem.\n" ); AutoResetEvent^ autoEvent = gcnew AutoResetEvent( false ); // Create some data. const int ArraySize = 10000; const int BufferSize = 1000; array<Byte>^byteArray = gcnew array<Byte>(ArraySize); (gcnew Random)->NextBytes( byteArray ); // Create two files and two State objects. FileStream^ fileWriter1 = gcnew FileStream( "C:\\Test1@##.dat",FileMode::Create,FileAccess::ReadWrite,FileShare::ReadWrite,BufferSize,true ); FileStream^ fileWriter2 = gcnew FileStream( "C:\\Test2@##.dat",FileMode::Create,FileAccess::ReadWrite,FileShare::ReadWrite,BufferSize,true ); State^ stateInfo1 = gcnew State( fileWriter1,autoEvent ); State^ stateInfo2 = gcnew State( fileWriter2,autoEvent ); // Asynchronously write to the files. fileWriter1->BeginWrite( byteArray, 0, byteArray->Length, gcnew AsyncCallback( &ThreadPoolTest::EndWriteCallback ), stateInfo1 ); fileWriter2->BeginWrite( byteArray, 0, byteArray->Length, gcnew AsyncCallback( &ThreadPoolTest::EndWriteCallback ), stateInfo2 ); // Wait for each callback to finish. autoEvent->WaitOne(); autoEvent->WaitOne(); fileWriter1->Close(); fileWriter2->Close(); Console::WriteLine( "\nEnding WorkItem.\n" ); // Signal Main that the work item is finished. dynamic_cast<AutoResetEvent^>(mainEvent)->Set(); } }; int main() { AutoResetEvent^ mainEvent = gcnew AutoResetEvent( false ); int workerThreads; int portThreads; ThreadPool::GetMaxThreads( workerThreads, portThreads ); Console::WriteLine( "\nMaximum worker threads: \t{0}" "\nMaximum completion port threads: {1}", workerThreads.ToString(), portThreads.ToString() ); ThreadPool::GetAvailableThreads( workerThreads, portThreads ); Console::WriteLine( "\nAvailable worker threads: \t{0}" "\nAvailable completion port threads: {1}\n", workerThreads.ToString(), portThreads.ToString() ); ThreadPool::QueueUserWorkItem( gcnew WaitCallback( &ThreadPoolTest::WorkItemMethod ), mainEvent ); // Since ThreadPool threads are background threads, // wait for the work item to signal before ending main(). mainEvent->WaitOne( 5000, false ); }
import System.*; import System.IO.*; import System.Security.Permissions.*; import System.Threading.*; import System.Threading.Thread; // Request permission to create two data files. /** @assembly FileIOPermissionAttribute(SecurityAction.RequestMinimum, All = "C:\\Test1@##.dat") */ /** @assembly FileIOPermissionAttribute(SecurityAction.RequestMinimum, All = "C:\\Test2@##.dat") */ class Test { public static void main(String[] args) { AutoResetEvent mainEvent = new AutoResetEvent(false); int workerThreads = 0; int portThreads = 0; ThreadPool.GetMaxThreads(workerThreads, portThreads); Console.WriteLine("\nMaximum worker threads: \t{0}" + "\nMaximum completion port threads: {1}", String.valueOf(workerThreads), String.valueOf(portThreads)); ThreadPool.GetAvailableThreads(workerThreads, portThreads); Console.WriteLine("\nAvailable worker threads: \t{0}" + "\nAvailable completion port threads: {1}\n", String.valueOf(workerThreads), String.valueOf(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); } //main } //Test 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; } //State } //State ThreadPoolTest() { } //ThreadPoolTest public static void WorkItemMethod(Object mainEvent) { Console.WriteLine("\nStarting WorkItem.\n"); AutoResetEvent autoEvent = new AutoResetEvent(false); // Create some data. final int arraySize = 10000; final int bufferSize = 1000; ubyte byteArray[] = new ubyte[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); ThreadPoolTest test = new ThreadPoolTest(); State stateInfo1 = test.new State(fileWriter1, autoEvent); State stateInfo2 = test.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(); } //WorkItemMethod static void EndWriteCallback(IAsyncResult asyncResult) { Console.WriteLine("Starting EndWriteCallback."); State stateInfo = ((State)(asyncResult.get_AsyncState())); int workerThreads = 0; int portThreads = 0; try { ThreadPool.GetAvailableThreads(workerThreads, portThreads); Console.WriteLine("\nAvailable worker threads: \t{0}" + "\nAvailable completion port threads: {1}\n", String.valueOf(workerThreads), String.valueOf(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."); } } //EndWriteCallback } //ThreadPoolTest

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