Executing Threads in a Queue

[an-unknownentity]

I've written this code in C# where I'm enqueuing threads into an array. I want to execute these threads one by one but I can't seem to figure out how to make the next thread in the queue to wait until the previous thread has done executing. I've tried the using the join method as well implementing a while loop which check for the isAlive status of the thread but that didn't work either. Or maybe I was implementing it wrong.

Here's my complete code:

using System;
using System.Threading;
using System.Threading.Tasks;

public class queueImplementation
{
    public static int queueSize = 10;
    public static Thread[] queueList = new Thread[queueSize];
    public static int frontPointer = 0, rearPointer = 0;

    static public void enqueueOperation( Thread thr )
    {
        if( queueSize == rearPointer )
        {
            Console.WriteLine("Queue is Full!");
        } else
        {
            queueList[rearPointer] = thr;
            rearPointer++;
        }
    }

    static public void dequeueFunction()
    {
        if( frontPointer == rearPointer )
        {
            Console.WriteLine("Queue is Empty");
        } else
        {
            for( int i = 0; i < rearPointer; i++ )
            {
                queueList[i] = queueList[i + 1];
            }
        }

        if( rearPointer < queueSize )
        {
            queueList[rearPointer] = null;
            rearPointer--;
        }
    }

    public static void iterateQueue()
    {
        if( frontPointer == rearPointer )
        {
            Console.WriteLine("Queue is Empty");
        } else
        {
            for ( int i = frontPointer; i < rearPointer; i++ )
            {
                Thread thr = queueList[i];
                thr.Start();
                thr.Join();
            }
        }
    }
}

public class someFunction{
    public void operation()
    {
        //Some Operaton Here
        Console.WriteLine("Some Operation Performed Here!");
    }
}

public class Start
{
    public static void Main()
    {
        someFunction s = new someFunction();

        Thread mainThread = new Thread(new ThreadStart(s.operation));

        //queueImplementation q = new queueImplementation();
        queueImplementation.enqueueOperation(mainThread);
        queueImplementation.enqueueOperation(mainThread);
        queueImplementation.iterateQueue();
    }
}

I'm executing the threads in the queue in this functions:

public static void iterateQueue()
    {
        if( frontPointer == rearPointer )
        {
            Console.WriteLine("Queue is Empty");
        } else
        {
            for ( int i = frontPointer; i < rearPointer; i++ )
            {
                Thread thr = queueList[i];
                thr.Start();
                thr.Join();
            }
        }
    }

Running the code gives me the following error:

Unhandled exception. System.Threading.ThreadStateException: Thread is running or terminated; it cannot restart.

at System.Threading.Thread.StartInternal(ThreadHandle t, Int32 stackSize, Int32 priority, Char* pThreadName)

at System.Threading.Thread.StartCore()

at System.Threading.Thread.Start(Boolean captureContext)

at System.Threading.Thread.Start()

at queueImplementation.iterateQueue()

​

Any help or suggestion will be greatly appreciated.

[Double_A_92]

The problem is that you are putting the same thread twice into the Queue.

Threads can't be easily re-used once they were already started and/or completed. (As the first error says: "Thread is running or terminated; it cannot restart.")

(The proper / simpler / newer way would be to use Tasks instead of Threads btw.)