CollectionBase.ICollection.SyncRoot Property

Definition

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

C#
object System.Collections.ICollection.SyncRoot { get; }

Property Value

An object that can be used to synchronize access to the CollectionBase.

Implements

Remarks

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:

C#
// 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.

Applies to

Product Versions
.NET Core 1.0, Core 1.1, Core 2.0, Core 2.1, Core 2.2, Core 3.0, Core 3.1, 5, 6, 7, 8, 9
.NET Framework 1.1, 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7, 4.7.1, 4.7.2, 4.8, 4.8.1
.NET Standard 2.0, 2.1
UWP 10.0

See also