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AbandonedMutexException.MutexIndex Property

Note: This property is new in the .NET Framework version 2.0.

Gets the index of the abandoned mutex that caused the exception, if known.

Namespace: System.Threading
Assembly: mscorlib (in mscorlib.dll)

public int MutexIndex { get; }
/** @property */
public int get_MutexIndex ()

public function get MutexIndex () : int

Property Value

The index, in the array of wait handles passed to the System.Threading.WaitHandle.WaitAny method, of the Mutex object that represents the abandoned mutex, or –1 if the index of the abandoned mutex could not be determined.

If the exception is thrown on a call to the System.Threading.WaitHandle.WaitAny method, this property returns the index of the abandoned mutex with the lowest index in the array of WaitHandle objects that was passed to WaitAny, or –1 if the abandoned mutex could not be identified. If the exception is thrown on a call to WaitOne or WaitAll, this property always returns –1.

The following code example executes a thread that abandons five mutexes. The abandoned mutexes are used to demonstrate the effects on the System.Threading.WaitHandle.WaitOne, WaitAny, and WaitAll method calls. The value of the MutexIndex property is displayed for the WaitAny call.

NoteNote

The call to WaitAny is interrupted by one of the abandoned mutexes. The other abandoned mutex could still cause an AbandonedMutexException to be thrown by subsequent wait methods.


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.
 */

import System.*;
import 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();

    /** @attribute MTAThread()
     */
    public static void main(String[] args)
    {
        // Start a thread that takes all five mutexes, and then
        // ends without releasing them.
        //
        System.Threading.Thread t = new System.Threading.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.get_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
        // ManualReset_Event 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.");
            if (waitFor.get_Item(index) instanceof Mutex) {
                ((Mutex)(waitFor.get_Item(index))).ReleaseMutex();
            }
        }
        catch (AbandonedMutexException ex) {
            Console.WriteLine("Exception on return from WaitAny at index {0}" 
                + "\r\n\tMessage: {1}", (Int32)ex.get_MutexIndex(),
                ex.get_Message());

            // Whether or not the exception was thrown, the current
            // thread owns the mutex, and must release it.
            //
            if (ex.get_Mutex() != null) ex.get_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 ManualReset_Event must be signaled by calling set_().
        dummy.Set();
        waitFor.set_Item(1, orphan4);
        waitFor.set_Item(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 WaitAny at index {0}" 
                + "\r\n\tMessage: {1}", (Int32)ex.get_MutexIndex(),
                ex.get_Message());
        }
        finally {
            // Whether or not the exception was thrown, the current
            // thread owns the mutexes, and must release them.
            //
            orphan4.ReleaseMutex();
            orphan5.ReleaseMutex();
        }
    } //main

    /** @attribute 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.");
    } //AbandonMutex
} //Example

/* 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.
 */

Windows 98, Windows 2000 SP4, Windows Millennium Edition, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

.NET Framework

Supported in: 2.0
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