Visual Basic Code for .NET Parallel Extensions Video


Here’s a great video with Stephen Toub and Jason Olson that gives a 15min overview of what’s new for managed developers doing parallel programming with .NET 4.0.


Video: Using the Parallel Extensions to the .NET Framework

Welcome back to another Visual Studio 2010 and .NET Framework 4.0 Week video. In this latest installment, we catch up with Stephen Toub, Senior Program Manager on the Parallel Computing Platform team. Stephen takes us through a whirlwind tour of many different Parallel Extensions features, showing them in action. Covered are features like Parallel LINQ, Parallel.For, the Task Parallel Library, and some of the new Coordination Data Structures.


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I’ve included a VB version of the code below, in case you want to follow along in Visual Basic. I’ve also attached the solution at the end of this post. The solution runs on Visual Studio 2010 Beta 2.




Code Snippet



  1. Imports System.Threading

  2. Imports System.Threading.Tasks

  3. Imports System.Collections.Concurrent


  4. Module Module1


  5.     Sub Main()

  6.         While True


  7.             ‘Non-Parallel LINQ example

  8.             Console.WriteLine(“Non-Parallel LINQ Example”)

  9.             Console.WriteLine(Time(Sub()

  10.                                        Dim dict = (From i In Enumerable.Range(0, 2000000)

  11.                                                   Where IsPrime(i)

  12.                                                   Select i).ToDictionary(Function(x) x)


  13.                                    End Sub))


  14.             ‘Parallel LINQ example (PLINQ)

  15.             Console.WriteLine(vbCrLf & “Parallel LINQ Example”)

  16.             Console.WriteLine(Time(Sub()

  17.                                        Dim dict = (From i In Enumerable.Range(0, 2000000).AsParallel

  18.                                                   Where IsPrime(i)

  19.                                                   Select i).ToDictionary(Function(x) x)


  20.                                    End Sub))


  21.             ‘Parallel, Ordered LINQ example

  22.             Console.WriteLine(vbCrLf & “Parallel & Ordered LINQ Example”)

  23.             Console.WriteLine(Time(Sub()

  24.                                        Dim dict = (From i In Enumerable.Range(0, 2000000).AsParallel.AsOrdered

  25.                                                   Where IsPrime(i)

  26.                                                   Select i).ToDictionary(Function(x) x)


  27.                                    End Sub))


  28.             ‘Non-Parallel, Non-LINQ (uses a For loop)

  29.             Console.WriteLine(vbCrLf & “Non-Parallel & Non-LINQ Example (uses a For loop)”)

  30.             Console.WriteLine(Time(Sub()

  31.                                        Dim primes = New Queue(Of Integer)

  32.                                        For i = 0 To 2000000

  33.                                            If IsPrime(i) Then primes.Enqueue(i)

  34.                                        Next

  35.                                    End Sub))


  36.             ‘Parallel, Non-LINQ (uses Parallel.For, which is part of the Parallel Task Library in System.Threading.Tasks).

  37.             Console.WriteLine(vbCrLf & “Parallel For Example”)

  38.             Console.WriteLine(Time(Sub()

  39.                                        ‘Queue is not thread safe.

  40.                                        ‘Dim primes = New Queue(Of Integer)


  41.                                        ‘Instead use ConcurrentQueue, which is a new .NET 4.0 collection in System.Collections.Concurrent.

  42.                                        Dim primes = New ConcurrentQueue(Of Integer)


  43.                                        Parallel.For(0, 2000000, Sub(i)

  44.                                                                     If IsPrime(i) Then primes.Enqueue(i)

  45.                                                                 End Sub)

  46.                                    End Sub))


  47.             Console.ReadLine()


  48.             ‘BlockingCollection Example

  49.             Dim primes2 = New BlockingCollection(Of Integer)

  50.             Dim t As Task = Task.Factory.StartNew(Sub()

  51.                                                       For Each prime In primes2.GetConsumingEnumerable()

  52.                                                           Console.WriteLine(prime)

  53.                                                       Next

  54.                                                   End Sub)

  55.             For i = 0 To 2000000

  56.                 If IsPrime(i) Then primes2.Add(i)

  57.             Next

  58.             primes2.CompleteAdding()

  59.             t.Wait()


  60.             Console.ReadLine()


  61.         End While

  62.     End Sub


  63.     Function IsPrime(ByVal valueToTest As Integer)

  64.         If valueToTest < 2 Then Return False

  65.         Dim bound As Integer = Math.Sqrt(valueToTest)

  66.         For i = 2 To bound

  67.             If valueToTest Mod i = 0 Then Return False

  68.         Next

  69.         Return True

  70.     End Function


  71.     Function Time(ByVal a As Action) As TimeSpan

  72.         Dim sw As Stopwatch = Stopwatch.StartNew()

  73.         a()

  74.         Return sw.Elapsed()

  75.     End Function

  76. End Module






IsPrimeParallel.zip

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