Limit Threads count

Question

I have a List with items that I want to download. I use a for Loop to iterate the list.

For each item in this List I start a new Thread that references the item. My Problem is that I want limit the maxDownload at the same time.

for (int i = downloadList.Count - 1; i >= 0; i--)
{
    downloadItem item = downloadList[i];
    if (item.Status != 1 && item.Status != 2)
    {
        ThreadStart starter = delegate { this.DownloadItem(ref item); };
        Thread t = new Thread(starter);
        t.IsBackground = true;
        t.Name = item.Name;
        t.Priority = ThreadPriority.Normal;
        t.Start();
    }
}

I read something about the ThreadPool, but then I can't reference my item. Can someone Help me? Thanks! :)

Edit:

I tested this:

ThreadPool.SetMaxThreads(maxDownloads, maxDownloads);
ThreadPool.SetMinThreads(maxDownloads, maxDownloads);
ThreadPool.QueueUserWorkItem(DownloadItem, ref item);

I don't know how I can reference my downloadItem with this thread.....

Answer 1

if you're using .NET 4, I'd strongly suggest using Parallel.ForEach (potentially on downloadList.Reverse())

so, something like:

Parallel.ForEach(downloadList.Reverse(), 
                 new ParallelOptions { MaxDegreeOfParallelism = 8 },
                 item => this.DownloadItem(item));

If you don't want the calling thread to block, you could QueueUserWorkItem this call, of course.