How to get Synchronize access to the Array in C#

Array.SyncRoot Property is used to get an object that can be used to synchronize access to the Array. An array is a group of like-typed variables that are referred to by a common name. Array class comes under the System namespace.

Important Points:

• Synchronization of an object is done so that only one thread can manipulate the data in the array.
• A property is a member of a class that provides a means for reading, writing and computing private data fields.
• Array.SyncRoot Property implements the System.Collections.ICollection interface.
• The synchronizing code cannot directly perform on the collection, so it must perform operations on the SyncRoot of the collection in order to guarantee the proper operation of collections that are derived from other objects.
• Retrieving the value of this property is an O(1) operation.

Syntax: arrayName.SyncRoot

Property Value: An object that can be used to synchronize access to the Array.

Example 1: In this code, we are using SyncRoot to get Synchronized access to the Array named arr, which is not a thread-safe procedure and can cause an exception. So to avoid the exception we lock the collection during the enumeration.

// C# program to illustrate the
// use of SyncRoot property
using System;
using System.Threading;
using System.Collections;

namespace sync_root {

class GFG {

    // Main Method
    static void Main(string[] args)
    {

        // Declaring an array
        Array arr = new int[] {12, 15, 20, 3, 6};

        // Using the SyncRoot property
        lock(arr.SyncRoot)
        {
            // foreach loop to display
            // the elements in arr
            foreach(Object i in arr)
                Console.WriteLine(i);
        }
    }
}
}

Output:

12
15
20
3
6

Example 2: In the below example we use SynRoot property with an array of objects of class X.

// C# program to depict the use
// of SyncRoot Property
// for an array of objects
using System;
using System.Threading;
using System.Collections;

namespace sync_root_2 {

// User defined class X
class X {

    int x;

    // defining Constructor
    public X()
    {
        x = 0;
    }

    // Method to get the value
    // stored in x
    public int getValue()
    {
        return x;
    }
}

// Driver Class
public class Program {

    // Main Method
    static void Main(string[] args)
    {
        // Declaring an array of objects
        // of type class X
        X[] obj = new X[5];

        // Calling the constructor
        // for each object
        for (int i = 0; i < 5; i++)
            obj[i] = new X();

        // Synchronizing the array
        lock(obj.SyncRoot)
        {
            // Displaying the value
            foreach(X element in obj)
                Console.WriteLine(element.getValue());
        }
    }
}
}

Output:

0
0
0
0
0

Reference:

• https://docs.microsoft.com/en-us/dotnet/api/system.array.syncroot?view=netframework-4.7.2