Serial Queue vs Parallel Queue using C#

Below is Enqueue and Dequeue using System.Collections in serial fashion.

publicstaticvoid Main()


  // Creates and initializes a new Queue. 

  for (int i = 0; i < 10000; i++) myQ.Enqueue(i);


  // Displays the properties and values of the Queue.

  int outerSum = action();


  Console.WriteLine(“outerSum = {0}, should be 49995000”, outerSum);


publicstaticint action()


  int localSum = 0;

  int localValue;

  for (int i = 0; i < 10000; i++)


    localValue = (int) myQ.Dequeue();

    localSum += localValue;


  return localSum;



You can convert the queue to utilize System.Collections.Concurrent to make the Enqueue and Dequeue parallel with Lambda expression =>.


staticvoid Main()


  // Construct a ConcurrentQueue.

  ConcurrentQueue<int> cq = newConcurrentQueue<int>();


  // Populate the queue.

  for (int i = 0; i < 10000; i++) cq.Enqueue(i);


  // Peek at the first element.

  int result;

  if (!cq.TryPeek(out result))


    Console.WriteLine(“CQ: TryPeek failed when it should have succeeded”);


  elseif (result != 0)


    Console.WriteLine(“CQ: Expected TryPeek result of 0, got {0}”, result);



  int outerSum = 0;

  // An action to consume the ConcurrentQueue.

  Action action = () =>


    int localSum = 0;

    int localValue;

    while (cq.TryDequeue(out localValue)) localSum += localValue;

    Interlocked.Add(ref outerSum, localSum);


  // Start 4 concurrent consuming actions.

  Parallel.Invoke(action, action, action, action);


  Console.WriteLine(“outerSum = {0}, should be 49995000”, outerSum);



My idea to blog the concurrent queue is from my colleague Joel Holder.

You can also download a single solution from The sample file name is ConAppQueue.rar My MSN ID is




About chanmingman

Since March 2011 Microsoft Live Spaces migrated to Wordpress ( till now, I have is over 1 million viewers. This blog is about more than 50% telling you how to resolve error messages, especial for Microsoft products. The blog also has a lot of guidance teaching you how to get stated certain Microsoft technologies. The blog also uses as a help to keep my memory. The blog is never meant to give people consulting services or silver bullet solutions. It is a contribution to the community. Thanks for your support over the years. Ming Man is Microsoft MVP since year 2006. He is a software development manager for a multinational company. With 25 years of experience in the IT field, he has developed system using Clipper, COBOL, VB5, VB6, VB.NET, Java and C #. He has been using Visual Studio (.NET) since the Beta back in year 2000. He and the team have developed many projects using .NET platform such as SCM, and HR based applications. He is familiar with the N-Tier design of business application and is also an expert with database experience in MS SQL, Oracle and AS 400.
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