Joining Thread in C# programming

Joining two or more threads ensure that the execution of a thread is extended until the execution of other currently running threads is complete. To understand the concept of joining thread , let's create an application with the name ThreadJoin and add a project in it with the name NoJoin that help to execute the thread without joining them.

showing the code of NoJoin application :


using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace JOINING_THREADS.CS
{
    class Program
    {
        static void Main(string[] args)
        {
            Thread firstthread = new Thread(firstfunction);
            Thread secondthread = new Thread(secondfunction);
            Thread thirdthread = new Thread(thirdfunction);
            Console.WriteLine("threads starts...");
            firstthread.Start();
            secondthread.Start();
            thirdthread.Start();
            Console.WriteLine("the main() is ending...");
        }
        public static void firstfunction()
        {
            for (int num = 1; num <= 5; num++)
            {
                Console.WriteLine("first thread displays : \t"+num);
                Thread.Sleep(2000);
            }
        }
        public static void secondfunction()
        {
            for (int num = 1; num <= 5; num++)
            {
                Console.WriteLine("second thread displays : \t"+num);
                Thread.Sleep(5000);
            }
        }
        public static void thirdfunction()
        {
            for (int num = 1; num <= 5; num++)
            {
                Console.WriteLine("third thread displys : \t\t"+num);
                Thread.Sleep(7000);
            } Console.ReadKey();
        }

    }

}

output :

In this figure , you can see that the Main() thread terminates rapidly after starting the firstthread thread and the secondthread thread. However , if you want the main() thread to stay alive until the firstthread thread is alive , then apply the join() method to the firstthread thread.

To understand this more clearly , let's implement the join() method in the ThreadJoin application of the ThreadJoin project.

showing the code of ThreadJoin application :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace JOININ_A_THREAD.CS
{
    class Program
    {
        static void Main(string[] args)
        {
            Thread firstthread = new Thread(firstfunction);
            Thread secondthread = new Thread(secondfunction);
            Thread thirdthread = new Thread(thirdfunction);
            Console.WriteLine("starts thread..");
            firstthread.Start();
            secondthread.Start();
            thirdthread.Start();
            firstthread.Join();
        Console.WriteLine("\n the main() is ending..");
        }
        public static void firstfunction()
        {
            for (int num = 1; num <= 5; num++)
            {
                Console.WriteLine("first thread displays \t" + num);
                Thread.Sleep(2000);
            }
        }
        public static void secondfunction()
        {
            for (int num = 1; num <= 5; num++)
            {
                Console.WriteLine("second thread displays \t" + num);
                Thread.Sleep(4000);
            }
        }
        public static void thirdfunction()
        {
            for (int num = 1; num <= 5; num++)
            {
                Console.WriteLine("thread displays \t" + num);
                Thread.Sleep(6000);
            } Console.ReadKey();
        }
    }

}

output :

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