suppose i want to download multiple files with task parallel library and now i want to visualize how many threads are working at the time of debugging from VS2010 IDE ? here is one code snippet which download many files using TPL.

var list = new[] 
{ 
    "http://google.com", 
    "http://yahoo.com", 
    "http://stackoverflow.com" 
}; 

var tasks = Parallel.ForEach(list,
        s =>
        {
            using (var client = new WebClient())
            {
                Console.WriteLine("starting to download {0}", s);
                string result = client.DownloadString((string)s);
                Console.WriteLine("finished downloading {0}", s);
            }
        });

please guide me or redirect me to any article from where i can acquire the knowledge to see how many thread is running to complete my task.

var tasks = Parallel.ForEach(list,
    s =>
    {
        using (var client = new System.Net.WebClient())
        {
            Console.WriteLine("starting to download {0}", s);
            client.DownloadStringAsync(new Uri(s));
            noofthreads++;
            client.DownloadStringCompleted += client_DownloadStringCompleted;
            client.DownloadProgressChanged += client_DownloadProgressChanged;
        }
    });
int noofthreads = 0;
private void client_DownloadProgressChanged(object sender, System.Net.DownloadProgressChangedEventArgs e)
{
    throw new NotImplementedException();//here you can update UI with the progress
}
private void client_DownloadStringCompleted(object sender, System.Net.DownloadStringCompletedEventArgs e)
{
    Console.WriteLine("finished downloading {0}", s);
    noofthreads--;
    //here you can update UI with the complete status
}

try like this