AbandonedMutexException Klasse

Definition

public ref class AbandonedMutexException : Exception

public ref class AbandonedMutexException : SystemException

public class AbandonedMutexException : Exception

public class AbandonedMutexException : SystemException

[System.Runtime.InteropServices.ComVisible(false)]
[System.Serializable]
public class AbandonedMutexException : SystemException

type AbandonedMutexException = class
    inherit Exception

type AbandonedMutexException = class
    inherit SystemException

[<System.Runtime.InteropServices.ComVisible(false)>]
[<System.Serializable>]
type AbandonedMutexException = class
    inherit SystemException

Public Class AbandonedMutexException
Inherits Exception

Public Class AbandonedMutexException
Inherits SystemException

Vererbung

Object

Exception

AbandonedMutexException

Vererbung

Object

Exception

SystemException

AbandonedMutexException

Attribute

ComVisibleAttribute SerializableAttribute

Beispiele

Im folgenden Codebeispiel wird ein Thread ausgeführt, der fünf Mutexes aufgibt und deren Auswirkungen auf die WaitOneMethoden und WaitAllWaitAnyMethoden veranschaulicht. Der Wert der MutexIndex Eigenschaft wird für den WaitAny Aufruf angezeigt.

using System;
using System.Threading;

public class Example
{
    private static ManualResetEvent _dummy = new ManualResetEvent(false);

    private static Mutex _orphan1 = new Mutex();
    private static Mutex _orphan2 = new Mutex();
    private static Mutex _orphan3 = new Mutex();
    private static Mutex _orphan4 = new Mutex();
    private static Mutex _orphan5 = new Mutex();

    [MTAThread]
    public static void Main()
    {
        // Start a thread that takes all five mutexes, and then
        // ends without releasing them.
        //
        Thread t = new Thread(new ThreadStart(AbandonMutex));
        t.Start();
        // Make sure the thread is finished.
        t.Join();

        // Wait on one of the abandoned mutexes. The WaitOne returns
        // immediately, because its wait condition is satisfied by
        // the abandoned mutex, but on return it throws
        // AbandonedMutexException.
        try
        {
            _orphan1.WaitOne();
            Console.WriteLine("WaitOne succeeded.");
        }
        catch(AbandonedMutexException ex)
        {
            Console.WriteLine("Exception on return from WaitOne." +
                "\r\n\tMessage: {0}", ex.Message);
        }
        finally
        {
            // Whether or not the exception was thrown, the current
            // thread owns the mutex, and must release it.
            //
            _orphan1.ReleaseMutex();
        }

        // Create an array of wait handles, consisting of one
        // ManualResetEvent and two mutexes, using two more of the
        // abandoned mutexes.
        WaitHandle[] waitFor = {_dummy, _orphan2, _orphan3};

        // WaitAny returns when any of the wait handles in the 
        // array is signaled, so either of the two abandoned mutexes
        // satisfy its wait condition. On returning from the wait,
        // WaitAny throws AbandonedMutexException. The MutexIndex
        // property returns the lower of the two index values for 
        // the abandoned mutexes. Note that the Try block and the
        // Catch block obtain the index in different ways.
        //  
        try
        {
            int index = WaitHandle.WaitAny(waitFor);
            Console.WriteLine("WaitAny succeeded.");

            // The current thread owns the mutex, and must release
            // it.
            Mutex m = waitFor[index] as Mutex;
            if (m != null) m.ReleaseMutex();
        }
        catch(AbandonedMutexException ex)
        {
            Console.WriteLine("Exception on return from WaitAny at index {0}." +
                "\r\n\tMessage: {1}", ex.MutexIndex, ex.Message);

            // Whether or not the exception was thrown, the current
            // thread owns the mutex, and must release it.
            //
            if (ex.Mutex != null) ex.Mutex.ReleaseMutex();
        }

        // Use two more of the abandoned mutexes for the WaitAll call.
        // WaitAll doesn't return until all wait handles are signaled,
        // so the ManualResetEvent must be signaled by calling Set().
        _dummy.Set();
        waitFor[1] = _orphan4;
        waitFor[2] = _orphan5;

        // The signaled event and the two abandoned mutexes satisfy
        // the wait condition for WaitAll, but on return it throws
        // AbandonedMutexException. For WaitAll, the MutexIndex
        // property is always -1 and the Mutex property is always
        // null.
        //  
        try
        {
            WaitHandle.WaitAll(waitFor);
            Console.WriteLine("WaitAll succeeded.");
        }
        catch(AbandonedMutexException ex)
        {
            Console.WriteLine("Exception on return from WaitAll. MutexIndex = {0}." +
                "\r\n\tMessage: {1}", ex.MutexIndex, ex.Message);
        }
        finally
        {
            // Whether or not the exception was thrown, the current
            // thread owns the mutexes, and must release them.
            //
            _orphan4.ReleaseMutex();
            _orphan5.ReleaseMutex();
        }
    }

    [MTAThread]
    public static void AbandonMutex()
    {
        _orphan1.WaitOne();
        _orphan2.WaitOne();
        _orphan3.WaitOne();
        _orphan4.WaitOne();
        _orphan5.WaitOne();
        // Abandon the mutexes by exiting without releasing them.
        Console.WriteLine("Thread exits without releasing the mutexes.");
    }
}

/* This code example produces the following output:

Thread exits without releasing the mutexes.
Exception on return from WaitOne.
        Message: The wait completed due to an abandoned mutex.
Exception on return from WaitAny at index 1.
        Message: The wait completed due to an abandoned mutex.
Exception on return from WaitAll. MutexIndex = -1.
        Message: The wait completed due to an abandoned mutex.
 */

Option Explicit
Imports System.Threading

Public Class Example
    Private Shared _dummy As New ManualResetEvent(False)

    Private Shared _orphan1 As New Mutex()
    Private Shared _orphan2 As New Mutex()
    Private Shared _orphan3 As New Mutex()
    Private Shared _orphan4 As New Mutex()
    Private Shared _orphan5 As New Mutex()

    <MTAThread> _
    Public Shared Sub Main()
        ' Start a thread that takes all five mutexes, and then
        ' ends without releasing them.
        '
        Dim t As New Thread(AddressOf AbandonMutex)
        t.Start()
        ' Make sure the thread is finished.
        t.Join()

        ' Wait on one of the abandoned mutexes. The WaitOne returns
        ' immediately, because its wait condition is satisfied by
        ' the abandoned mutex, but on return it throws
        ' AbandonedMutexException.
        Try
            _orphan1.WaitOne()
            Console.WriteLine("WaitOne succeeded.")
        Catch ex As AbandonedMutexException
            Console.WriteLine("Exception on return from WaitOne." _
                & vbCrLf & vbTab & "Message: " _
                & ex.Message) 
        Finally
            ' Whether or not the exception was thrown, the current
            ' thread owns the mutex, and must release it.
            '
            _orphan1.ReleaseMutex()
        End Try

        ' Create an array of wait handles, consisting of one
        ' ManualResetEvent and two mutexes, using two more of the
        ' abandoned mutexes.
        Dim waitFor(2) As WaitHandle
        waitFor(0) = _dummy
        waitFor(1) = _orphan2
        waitFor(2) = _orphan3

        ' WaitAny returns when any of the wait handles in the 
        ' array is signaled, so either of the two abandoned mutexes
        ' satisfy its wait condition. On returning from the wait,
        ' WaitAny throws AbandonedMutexException. The MutexIndex
        ' property returns the lower of the two index values for 
        ' the abandoned mutexes. Note that the Try block and the
        ' Catch block obtain the index in different ways.
        '  
        Try
            Dim index As Integer = WaitHandle.WaitAny(waitFor)
            Console.WriteLine("WaitAny succeeded.")

            Dim m As Mutex = TryCast(waitFor(index), Mutex)

            ' The current thread owns the mutex, and must release
            ' it.
            If m IsNot Nothing Then m.ReleaseMutex()
        Catch ex As AbandonedMutexException
            Console.WriteLine("Exception on return from WaitAny at index " _
                & ex.MutexIndex & "." _
                & vbCrLf & vbTab & "Message: " _
                & ex.Message) 

            ' Whether or not the exception was thrown, the current
            ' thread owns the mutex, and must release it.
            '
            If ex.Mutex IsNot Nothing Then ex.Mutex.ReleaseMutex()            
        End Try

        ' Use two more of the abandoned mutexes for the WaitAll call.
        ' WaitAll doesn't return until all wait handles are signaled,
        ' so the ManualResetEvent must be signaled by calling Set(). 
        _dummy.Set()
        waitFor(1) = _orphan4
        waitFor(2) = _orphan5

        ' The signaled event and the two abandoned mutexes satisfy
        ' the wait condition for WaitAll, but on return it throws
        ' AbandonedMutexException. For WaitAll, the MutexIndex
        ' property is always -1 and the Mutex property is always
        ' Nothing.
        '  
        Try
            WaitHandle.WaitAll(waitFor)
            Console.WriteLine("WaitAll succeeded.")
        Catch ex As AbandonedMutexException
            Console.WriteLine("Exception on return from WaitAll. MutexIndex = " _
                & ex.MutexIndex & "." _
                & vbCrLf & vbTab & "Message: " _
                & ex.Message) 
        Finally
            ' Whether or not the exception was thrown, the current
            ' thread owns the mutexes, and must release them.
            '
            CType(waitFor(1), Mutex).ReleaseMutex()
            CType(waitFor(2), Mutex).ReleaseMutex()
        End Try
    End Sub

    <MTAThread> _
    Public Shared Sub AbandonMutex()
        _orphan1.WaitOne()
        _orphan2.WaitOne()
        _orphan3.WaitOne()
        _orphan4.WaitOne()
        _orphan5.WaitOne()
        ' Abandon the mutexes by exiting without releasing them.
        Console.WriteLine("Thread exits without releasing the mutexes.")
    End Sub
End Class

' This code example produces the following output:
'
'Thread exits without releasing the mutexes.
'Exception on return from WaitOne.
'        Message: The wait completed due to an abandoned mutex.
'Exception on return from WaitAny at index 1.
'        Message: The wait completed due to an abandoned mutex.
'Exception on return from WaitAll. MutexIndex = -1.
'        Message: The wait completed due to an abandoned mutex.

Hinweise

Wenn ein Thread einen Mutex verlässt, wird die Ausnahme im nächsten Thread ausgelöst, der den Mutex erhält. Der Thread kann den Mutex abrufen, da er bereits auf den Mutex wartete, oder weil er zu einem späteren Zeitpunkt in den Mutex eingeht.

Ein verlassener Mutex weist auf einen schwerwiegenden Programmierfehler hin. Wenn ein Thread beendet wird, ohne den Mutex freizugeben, befinden sich die durch den Mutex geschützten Datenstrukturen möglicherweise nicht in einem konsistenten Zustand. Vor Version 2.0 von .NET Framework waren solche Probleme schwer zu erkennen, da keine Ausnahme ausgelöst wurde, wenn eine Wartezeit als Ergebnis eines abgebrochenen Mutex abgeschlossen wurde. Weitere Informationen finden Sie in der Mutex Klasse.

Der nächste Thread zum Anfordern des Besitzes des Mutex kann diese Ausnahme behandeln und fortfahren, vorausgesetzt, die Integrität der Datenstrukturen kann überprüft werden.

Weitere Informationen

• Mutex
• Mutex