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CollectionBase.ICollection.SyncRoot Property

Gets an object that can be used to synchronize access to the CollectionBase.

Namespace:  System.Collections
Assembly:  mscorlib (in mscorlib.dll)
Object ICollection.SyncRoot { get; }

Property Value

Type: System.Object
An object that can be used to synchronize access to the CollectionBase.

Implements

ICollection.SyncRoot

Derived classes can provide their own synchronized version of the CollectionBase using the SyncRoot property. The synchronizing code must perform operations on the SyncRoot of the CollectionBase, not directly on the CollectionBase. This ensures proper operation of collections that are derived from other objects. Specifically, it maintains proper synchronization with other threads that might be simultaneously modifying the CollectionBase object.

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:

// Get the ICollection interface from the CollectionBase 
// derived class.
ICollection myCollection = myCollectionBase;
lock(myCollection.SyncRoot)
{
    foreach (object item in myCollection)
    {
        // Insert your code here.
    }
}

Retrieving the value of this property is an O(1) operation.

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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