Question

I have a function like this:

private void GetRSS(int start, int end)
{
    for (int i = start; i < end; i++)
    {
        string content = string.Empty;
        using (WebClient client = new WebClient())
        {
            //some code here get html content
        }
        // some code here parse content
    }
}

In order to minimize the amount of time running to get all the needed data, I would like to run the function 4 times with different ranges at the same time and then merge the results or use a thread safe list or dictionary.

My question is, how could I run this function in 4 separated threads and still be able to control if one of the threads still working or not to know when it ends ?

My first idea was to declare each thread:

private Thread _controler;
private Thread _worker1;
private Thread _worker2;
private Thread _worker3;
private Thread _worker4;
private bool _isRunning = false;

Then I would start the controler and from inside the controler I would call each thread to execute the function above and keep track of each thread from the controler, something like:

private void _ControlerStart()
{
    _worker1 = new Thread(GetRSS);
    try
    {
        _worker1.Start(1, 7711);
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.ToString());
    }
    // repeat the above to all the 4 threads
    _isRunning = true;
    while (_isRunning)
    {
        if (_worker1.ThreadState != ThreadState.Running && _worker2.ThreadState != ThreadState.Running && _worker3.ThreadState != ThreadState.Running && _worker4.ThreadState != ThreadState.Running)
            _isRunning = false;
    }
    MessageBox.Show("Done");
}

While thinking on all this mess above I realize d that this is not the best way to do what I wanted and here I am ;).

How can I manage more than 1 thread to run the same function and yet be able to know when each thread has ended working to close or save or merge the data or do whatever else I have left to do from a main thread?

Answer 1

private static void GetRSS(int start, int end)
{
    var bunchSize = (end - start) / 4 + 1;

    var threads = new List<Thread>();

    for (int i = 0; i < 4; i++)
    {
        var currStart = start + i * bunchSize;
        var currEnd = currStart + bunchSize;

        if (currEnd > end)
        {
            currEnd = end;
        }

        var thread = new Thread(() =>
                                    {
                                        // thread logic using currStart and currEnd

                                        string content = string.Empty;
                                        using (WebClient client = new WebClient())
                                        {
                                            //some code here get html content
                                        }
                                        // some code here parse content
                                    });

        threads.Add(thread);
        thread.Start();
    }

    foreach (var thread in threads)
    {
        thread.Join();
    }
}