Multithreading / Parallel Processing in C#

Question

I have 4 tasks to complete using multithreading concept. and I have 4 Waitress.

How to assign the waitress that are free to handle either one of the task??

-I kept on getting duplicated data (For eg : 4 Thread doing the similar task) -If i used lock, it locks 1 thread to do 4 tasks which is not wat i want

my code:

 private void MTDemo()
        {
                String threadName = Thread.CurrentThread.Name;

                while (true)
                {
                    int numWaitingCustomer = 0;
                    Int32.TryParse(textBox1.Text, out numWaitingCustomer);

                    if (numWaitingCustomer > 0)
                    {

                        String takeOrderString = String.Format("Take order {0},{1}", threadName, numWaitingCustomer);
                        String serveMeal = String.Format("Serve meal {0},{1}",threadName, numWaitingCustomer);
                        String billCustomer = String.Format("Bill Customer {0},{1}", threadName, numWaitingCustomer);
                        String cleanTable = String.Format("Clean Table {0},{1}", threadName, numWaitingCustomer);
                        OutputMessage1(takeOrderString); Thread.Sleep(500);
                        OutputMessage1(serveMeal); Thread.Sleep(500);
                        OutputMessage1(billCustomer); Thread.Sleep(500);
                        OutputMessage1(cleanTable); Thread.Sleep(500);
                        numWaitingCustomer--;
                        SetControlPropertyValue(textBox1, "text", numWaitingCustomer.ToString());
                    }
                }
            }

Answer 1

Have each thread loop through the task list and complete the nth task, so waitress one will complete tasks 0,4,8... waitress 2 complete tasks 1,5,9... etc.

for(int i = threadNumber; i < taskList.length-threadNumber; i = i*totalThreads+ThreadNumber) {
    ...
}