How to get Synchronize access to the Stack in C#

Last Updated : 18 Feb, 2019

Stack.SyncRoot Property is used to get an object which can be used to synchronize access to the Stack. Stack represents last-in, first out collection of object. It is used when you need last-in, first-out access to items. When you add an item in the list, it is called pushing the item and when you remove it, it is called popping the item. This class comes under System.Collections namespace.

Syntax: public virtual object SyncRoot { get; }

Property Value: An object which can be used to synchronize access to the Stack.

Important Points:

Synchronization of an object is done so that only one thread can manipulate the data in the Stack.
A property is a member of a class that provides a means for reading, writing and computing private data fields.
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.

Below programs illustrate the use of the above-discussed property:

Example 1: In this code, we are using SyncRoot to get Synchronized access to the Stack named st, 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 of 
// the Stack 
using System; 
using System.Threading; 
using System.Collections; 
  
namespace sync_root { 
  
class GFG { 
  
    // Main Method 
    static void Main(string[] args) 
    { 
  
        // Declaring an Stack 
        Stack st = new Stack(); 
  
        // Adding elements to Stack 
        st.Push(1); 
        st.Push(2); 
        st.Push(3); 
        st.Push(4); 
        st.Push(5); 
  
        // Using the SyncRoot property 
        lock(st.SyncRoot) 
        { 
            // foreach loop to display 
            // the elements in st 
            foreach(Object i in st) 
                Console.WriteLine(i); 
        } 
    } 
} 
} 

Output:

Example 2:

// C# program to illustrate the 
// use of SyncRoot property of 
// the Stack 
using System; 
using System.Threading; 
using System.Collections; 
  
namespace sync_root { 
  
class GFG { 
  
    // Main Method 
    static void Main(string[] args) 
    { 
  
        // Declaring an Stack 
        Stack st = new Stack(); 
  
        // Adding elements to Stack 
        st.Push("C"); 
        st.Push("C++"); 
        st.Push("Java"); 
        st.Push("C#"); 
        st.Push("HTML"); 
  
        // Using the SyncRoot property 
        lock(st.SyncRoot) 
        { 
            // foreach loop to display 
            // the elements in st 
            foreach(Object i in st) 
                Console.WriteLine(i); 
        } 
    } 
} 
} 