Pause threads

There used to be a way to pause threads using the Pause() method. But this is now deprecated, so you must use alternative methods, such as WaitHandles. To demonstrate this there is a combined application that covers Pause/Resume and Abort of background threads

C# Sample Code : ThreadInterrupt

using System;
using System.Threading;

namespace ThreadInterrupt
{
   class Program
   {

       public static Thread sleeper;
       public static Thread waker;

       public static void Main(string[] args)
       {
           Console.WriteLine("Enter Main method");
           sleeper = new Thread(new ThreadStart(PutThreadToSleep));
           waker = new Thread(new ThreadStart(WakeThread));
           sleeper.Start();
           waker.Start();
           Console.WriteLine("Exiting Main method");
           Console.ReadLine();

       }

       //thread sleeper threadStart
       private static void PutThreadToSleep()
       {
           for (int i = 0; i < 50; i++)
           {
               Console.Write(i + " ");
               if (i == 10 || i == 20 || i == 30)
               {
                   try
                   {
                       Console.WriteLine("Sleep, Going to sleep at {0}",
                           i.ToString());
                       Thread.Sleep(20);
                   }
                   catch (ThreadInterruptedException e)
                   {
                       Console.WriteLine("Forcibly ");
                   }
                   Console.WriteLine("woken");
               }
           }
       }

       //thread waker threadStart
       private static void WakeThread()
       {

           for (int i = 51; i < 100; i++)
           {
               Console.Write(i + " ");

               if (sleeper.ThreadState == ThreadState.WaitSleepJoin)
               {
                   Console.WriteLine("Interrupting sleeper");
                   sleeper.Interrupt();
               }
           }

       }
   }
}

What is Thread Interrupt?

When a thread is put to sleep, the thread goes into the WaitSleepJoin state. If the thread is in this state it may be placed back in the scheduling queue by the use of the Interrupt method. Calling Interrupt when a thread is in the WaitSleepJoin state will cause a ThreadInterruptedException to be thrown, so any code that is written needs to catch this.

C# Sample code : for Thread.Sleep

using System;
using System.Threading;

namespace ThreadSleep
{
   class Program
   {

       public static Thread T1;
       public static Thread T2;

       public static void Main(string[] args)
       {
           Console.WriteLine("Enter Main method");

           T1 = new Thread(new ThreadStart(Count1));
           T2 = new Thread(new ThreadStart(Count2));
           T1.Start();
           T2.Start();
           Console.WriteLine("Exit Main method");
           Console.ReadLine();

       }

       //thread T1 threadStart
       private static void Count1()
       {
           Console.WriteLine("Enter T1 counter");
           for (int i = 0; i < 50; i++)
           {
               Console.Write(i + " ");
               if (i == 10)
                   Thread.Sleep(1000);
           }
           Console.WriteLine("Exit T1 counter");
       }

       //thread T2 threadStart
       private static void Count2()
       {
           Console.WriteLine("Enter T2 counter");
           for (int i = 51; i < 100; i++)
           {
               Console.Write(i + " ");
               if (i == 70)
                   Thread.Sleep(5000);
           }
           Console.WriteLine("Exit T2 counter");
       }
   }
}

C# Sample code : for Join 2 Threads

using System.Threading;

namespace ThreadJoin
{
   class Program
   {

       public static Thread T1;
       public static Thread T2;

       public static void Main(string[] args)
       {
           T1 = new Thread(new ThreadStart(First));
           T2 = new Thread(new ThreadStart(Second));
           T1.Name = "T1";
           T2.Name = "T2";
           T1.Start();
           T2.Start();
           Console.ReadLine();

       }

       //thread T1 threadStart
       private static void First()
       {
           for (int i = 0; i < 5; i++)
           {
               Console.WriteLine(
                   "T1 state [{0}], T1 showing {1}",
                   T1.ThreadState,  i.ToString());
           }
       }

       //thread T2 threadStart
       private static void Second()
       {
           //what the state of both threads
           Console.WriteLine(
               "T2 state [{0}] just about to Join, T1 state [{1}], CurrentThreadName={2}",
               T2.ThreadState, T1.ThreadState,
               Thread.CurrentThread.Name);

           //join T1
           T1.Join();

           Console.WriteLine(
               "T2 state [{0}] T2 just joined T1, T1 state [{1}], CurrentThreadName={2}",
               T2.ThreadState, T1.ThreadState,
               Thread.CurrentThread.Name);

           for (int i = 5; i < 10; i++)
           {
               Console.WriteLine(
                   "T2 state [{0}], T1 state [{1}], CurrentThreadName={2} showing {3}",
                   T2.ThreadState, T1.ThreadState,
                   Thread.CurrentThread.Name, i.ToString());
           }

           Console.WriteLine(
               "T2 state [{0}], T1 state [{1}], CurrentThreadName={2}",
               T2.ThreadState, T1.ThreadState,
               Thread.CurrentThread.Name);
       }
   }
}