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Queue.IsSynchronized Property

Gets a value indicating whether access to the Queue is synchronized (thread safe).

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

'Declaration
Public Overridable ReadOnly Property IsSynchronized As Boolean
'Usage
Dim instance As Queue 
Dim value As Boolean 

value = instance.IsSynchronized

Property Value

Type: System.Boolean
true if access to the Queue is synchronized (thread safe); otherwise, false. The default is false.

Implements

ICollection.IsSynchronized

To guarantee the thread safety of the Queue, all operations must be done through the wrapper returned by the Synchronized method.

Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

The following code example shows how to lock the collection using the SyncRoot during the entire enumeration. Retrieving the value of this property is an O(1) operation.

Dim myCollection As New Queue()
 Dim item As Object
 SyncLock myCollection.SyncRoot
  For Each item In myCollection
  ' Insert your code here.
  Next item
 End SyncLock

The following example shows how to synchronize a Queue, determine if a Queue is synchronized, and use a synchronized Queue.

Imports System
Imports System.Collections

Public Class SamplesQueue    

    Public Shared Sub Main()

        ' Creates and initializes a new Queue. 
        Dim myQ As New Queue()
        myQ.Enqueue("The")
        myQ.Enqueue("quick")
        myQ.Enqueue("brown")
        myQ.Enqueue("fox")

        ' Creates a synchronized wrapper around the Queue. 
        Dim mySyncdQ As Queue = Queue.Synchronized(myQ)

        ' Displays the sychronization status of both Queues. 
        Dim msg As String 
        If myQ.IsSynchronized Then
            msg = "synchronized" 
        Else
            msg = "not synchronized" 
        End If
        Console.WriteLine("myQ is {0}.", msg)
        If mySyncdQ.IsSynchronized Then
            msg = "synchronized" 
        Else
            msg = "not synchronized" 
        End If
        Console.WriteLine("mySyncdQ is {0}.", msg)
    End Sub 
End Class 

' This code produces the following output. 
'  
' myQ is not synchronized. 
' mySyncdQ is synchronized. 

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0, 1.0

XNA Framework

Supported in: 3.0, 2.0, 1.0
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