CODEWITHSUNDEEP
c#multithreadingthread-safety
user1438082
user1438082

Reputation: 2748

Application Stress Test Error

I am stress testing my application and have written a simple test to spawn hundreds of threads that call a method. The code below works fine for 1000 threads and 100 ms delay.

In the code below when the number of threads is 2000 and the delay is 100 i get the error Cannot load the "shell32.dll" DLL into memory in the catch statement for radButtonEmptyThread_Click

  1. How do i fix this?
  2. The value written "Debug.Print(count.ToString());" is always 1000 - why?

C# Code

private void radButtonEmptyThread_Click(object sender, EventArgs e)
        {
            try
            {

                for (int i = 0; i < int.Parse(radTextBoxWaitThreads.Text); i++)
                {
                    Thread Trd = new Thread(() => EmptyThreadRequest(int.Parse(radTextBoxFloodDelay.Text), i));
                    Trd.IsBackground = true;
                    Trd.Start();
                }
            }
            catch (Exception ex)
            {

                MessageBox.Show(ex.Message.ToString());

            }
        }

        private void EmptyThreadRequest(int delay, int count)
        {

            try
            {

                System.Threading.Thread.Sleep(delay);
                Debug.Print(count.ToString());


            }

            catch (Exception ex)
            {

                MessageBox.Show(ex.Message.ToString());

            }
        }

    }

Upvotes: 1

Views: 668

Answers (3)

user1438082
user1438082

Reputation: 2748

C# Code

private void radButtonCallEmptyTasks_Click(object sender, EventArgs e)
{
    try
    {

        for (int i = 0; i < int.Parse(radTextBoxWaitThreads.Text); i++)
        {

            // Create a task and supply a user delegate by using a lambda expression. 
            var taskA = new Task(() => EmptyTaskRequest(int.Parse(radTextBoxFloodDelay.Text), i));
            // Start the task.
            taskA.Start();
        }
    }
    catch (Exception ex)
    {

        MessageBox.Show(ex.Message.ToString());

    }
}



private void EmptyTaskRequest(int delay, int count)
{

    try
    {

        System.Threading.Thread.Sleep(delay);
        Debug.Print(count.ToString());


    }

    catch (Exception ex)
    {

        MessageBox.Show(ex.Message.ToString());

    }
}

}

Upvotes: -1

John
John

Reputation: 631

To deal with the captured variable issue, inside the loop do this:

int x = i;
Thread Trd = new Thread(() => EmptyThreadRequest(int.Parse(radTextBoxFloodDelay.Text), x));

And of course, consider using Tasks.

2000 is a functional limit enforced by Windows. I think it might have something to do with minimum stack allocated to each thread, but I would not bet my life on it. Tasks are very light weight threads, prefer them over threads when possible.

Upvotes: 1

Kendall Frey
Kendall Frey

Reputation: 44336

  1. Stop creating so many threads. That's very resource-intensive. Instead, use Tasks.

  2. i is a captured variable, which means the threads all access the original variable, not a copy. If you create a copy of the variable inside the loop, it will work as expected.

Upvotes: 2

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