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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

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()
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. 

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0
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