public class Consumer
    {
        Queue<int> queue;
        Object lockObject;

        public Consumer(Queue<int> queue, Object lockObject)
        {
            this.queue = queue;
            this.lockObject = lockObject;
        }

        public void consume(string filepath)
        {
            int item = 0;


            while (true)
            {
                lock (lockObject)
                {
                    if (queue.Count == 0)
                    {
                        Monitor.PulseAll(lockObject);
                        continue;
                    }

                    item = queue.Dequeue();
                    if (item == 0)
                    {
                        break;
                    }

                   //do some staff
                }

            }

        }
    }




    public class Producer 
    {
        Queue<int> queue;
        Object lockObject;

        public int ProgressPercent = 0;
        int TotalProducedElements = 0;
        public bool check1 = false;

        public Producer(Queue<int> queue, Object lockObject)
        {
            this.queue = queue;
            this.lockObject = lockObject;
        }

        private bool IsPrime(int num)
        {
            if (num == 0)
                return true;
            num = Math.Abs(num);
            for (int i = 2; i <= Math.Sqrt(num); i++)
                if (num % i == 0)
                    return false;
            return true;
        }

        public void produce(int target)
        { 
            try
            {
                int seq = 0;
                while (seq++ < target)
                {

                    lock (lockObject)
                    {
                        int item = seq;
                        if (IsPrime(item))
                        {
                            queue.Enqueue(item);

                        }
                        TotalProducedElements++;

                        ProgressPercent = seq;

                        if (queue.Count == 0)
                        {
                            Monitor.PulseAll(lockObject);
                        }
                    }
                }
                queue.Enqueue(0);
              }
            catch (Exception e)
            {
            }

        }
    }
}

 private void Start_Click(object sender, EventArgs e)
    {           

                    Object lockObj = new object(); 

                    Queue<int> queue = new Queue<int>();  

                    Producer p = new Producer(queue, lockObj);

                    Consumer c = new Consumer(queue, lockObj);



                    int target = int.Parse(TargetText.Text);
                    string path = Path.Text;

                    Thread Thread1 = new Thread(() => p.produce(target));
                    Thread Thread2 = new Thread(()=>c.consume(path));

                    Thread1.Start();



                    Thread2.Start();
                   progressBar1.Maximum = target;

                  while(true)
                       {
                         if(p.ProgressPercent==0)
                            {
                               Thread.sleep(1000);
                            }
                            else
                             {
                               progressBar1.Value=p.ProgressPercent;
                             }

                        }

                 }

Tengo dos clases trabajando en la misma cola. uno para producir un conjunto de enteros y el segundo es consumir esos enteros de la cola.

Y durante todo esto quiero actualizar mi barra de progreso en ese porcentaje. Entonces, ¿cómo actualizar la barra de progreso del consumidor sin bloquear para mi GUI?

Nota que he usadoprogressbar.Invoke ydelegate pero no funcionó