Part 92 - Significance of Thread.Join and Thread.IsAlive functions

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Part 90 - Passing data to the Thread function in a type safe manner
Part 91 - Retrieving data from Thread function using callback method



In this video we will discuss, the significance of Thread.Join and Thread.IsAlive functions with an example. 

Join blocks the current thread and makes it wait until the thread on which Join method is invoked completes. Join method also has a overload where we can specify the timeout. If we don't specify the timeout the calling thread waits indefinitely, until the thread on which Join() is invoked completes. This overloaded Join(int millisecondsTimeout) method returns boolean. True if the thread has terminated otherwise false. Join is particularly useful when we need to wait and collect result from a thread execution or if we need to do some cleanup after the thread has completed.

IsAlive returns boolean. True if the thread is still executing otherwise false.



Program code used in the demo:

using System;

using System.Threading;

namespace ThreadingExample

{

    class Program

    {

        public static void Main()

        {

            Console.WriteLine("Main Started");

            Thread T1 = new Thread(Program.Thread1Function);

            T1.Start();

            Thread T2 = new Thread(Program.Thread2Function);

            T2.Start();

            if (T1.Join(1000))

            {

                Console.WriteLine("Thread1Function completed");

            }

            else

            {

                Console.WriteLine("Thread1Function hot not completed in 1 second");

            }

            T2.Join();

            Console.WriteLine("Thread2Function completed");

            for (int i = 1; i <= 10; i++)

            {

                if (T1.IsAlive)

                {

                    Console.WriteLine("Thread1Function is still doing it's work");

                    Thread.Sleep(500);

                }

                else

                {

                    Console.WriteLine("Thread1Function Completed");

                    break;

                }

            }

            Console.WriteLine("Main Completed");

        }

        public static void Thread1Function()

        {

            Console.WriteLine("Thread1Function started");

            Thread.Sleep(5000);

            Console.WriteLine("Thread1Function is about to return");

        }

        public static void Thread2Function()

        {

            Console.WriteLine("Thread2Function started");

        }

    }

}