Angel \”Java\” Lopez on Blog

December 13, 2010

Azure: Multithreads in Worker Role, an example

Filed under: .NET, Azure, Cloud Computing, Distributed Computing — ajlopez @ 9:41 am

In my previous post, I implemented a simple worker role, consuming and producing numbers from/to a queue. Now, I have a new app:

The worker role implements the generation of a Collatz sequence. See:

You can download the solution from my AjCodeKatas Google project. The code is at:

The initial page is simple:

The number range is send to the queue:

protected void btnProcess_Click(object sender, EventArgs e)
    int from = Convert.ToInt32(txtFromNumber.Text);
    int to = Convert.ToInt32(txtToNumber.Text);
    for (int k=from; k<=to; k++) 
        CloudQueueMessage msg = new CloudQueueMessage(k.ToString());

The worker role gets each of these message, and calculates the Collatz sequence:

I added a new feature in Azure.Library: a MessageProcessor that can consumes message from a queue, in its own thread:

public MessageProcessor(CloudQueue queue, Func<CloudQueueMessage, bool> process)
    this.queue = queue;
    this.process = process;
public void Start()
    Thread thread = new Thread(new ThreadStart(this.Run));
public void Run()
    while (true)
            CloudQueueMessage msg = this.queue.GetMessage();
            if (this.ProcessMessage(msg))
        catch (Exception ex)
            Trace.WriteLine(ex.Message, "Error");
public virtual bool ProcessMessage(CloudQueueMessage msg)
    if (msg != null && this.process != null)
        return this.process(msg);
    Trace.WriteLine("Working", "Information");
    return false;

Then, the worker role is launching a fixed number (12) of MessageProcessor. In this way, each instance is dedicated to process many message. I guess that this is not needed in this example. But it was an easy “proof of concept” to test the idea. Part of Run method in worker role;

QueueUtilities qutil = new QueueUtilities(account);
CloudQueue queue = qutil.CreateQueueIfNotExists("numbers");
CloudQueueClient qclient = account.CreateCloudQueueClient();
for (int k=0; k<11; k++) 
    CloudQueue q = qclient.GetQueueReference("numbers");
    MessageProcessor p = new MessageProcessor(q, this.ProcessMessage);
MessageProcessor processor = new MessageProcessor(queue, this.ProcessMessage);

The ProcessMessage is in charge of the real work:

private bool ProcessMessage(CloudQueueMessage msg)
    int number = Convert.ToInt32(msg.AsString);
    List<int> numbers = new List<int>() { number };
    while (number > 1)
        if ((number % 2) == 0)
            number = number / 2;
            number = number * 3 + 1;
    StringBuilder builder = new StringBuilder();
    foreach (int n in numbers)
        builder.Append(" ");
    Trace.WriteLine(builder.ToString(), "Information");
    return true;

The code of this example is in my

Next steps: more distributed apps (genetic algorithm, web crawler…)

Keep tuned!

Angel “Java” Lopez

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