Basic BlockingCollection Producer Consumer in VB.NET

Question

I have been struggling for the last few hours to get a basic implementation of BlockingCollection to work. I cannot seem to find a tutorial in VB.NET for the life of me, so have been trying to get something working from tutorials in C#.

I just want to get a basic implementation working so I can progress to doing what I actually need. But I am stuck.

This is my code currently:

Dim blockingCollection As BlockingCollection(Of String) = New BlockingCollection(Of String)
        Dim count As Integer = 0

        Task.Factory.StartNew(Sub()
                                  While (True)
                                      blockingCollection.Add("value" + count)
                                      count = count + 1
                                  End While
                              End Sub)

        Task.Factory.StartNew(Sub()
                                  For Each value As String In blockingCollection.GetConsumingEnumerable()
                                      Debug.Print("Worker 1: " + value)
                                  Next
                              End Sub)

I get no output from running this, just the following exceptions:

A first chance exception of type 'System.FormatException' occurred in mscorlib.dll A first chance exception of type 'System.FormatException' occurred in Microsoft.VisualBasic.dll A first chance exception of type 'System.InvalidCastException' occurred in Microsoft.VisualBasic.dll

I have been googling persistently for the past few hours to try and resolve this, but to no avail. Hopefully someone here can help.

Thanks

Put Option Strict On at the top of the source code file and the compiler will tell you about the problem. Avoid adding a string and a number, use count.ToString(). Also shows you that it is important to *check* if a task completed successfully. Use ContinueWith() with TaskContinuationOptions.OnlyOnFaulted to report exceptions. — Hans Passant, Mar 15 '14 at 12:46

dbasnett · Accepted Answer · 2014-03-16T09:39:28.350

1

This code executes, though I don't know what it is that you want.

    Dim blockingCollection As BlockingCollection(Of String) = New BlockingCollection(Of String)
    Dim count As Integer = 0

    Task.Factory.StartNew(Sub()
                              While True
                                  blockingCollection.Add("value" & count.ToString)
                                  count = count + 1
                              End While
                          End Sub)

    Task.Factory.StartNew(Sub()
                              For Each value As String In blockingCollection.GetConsumingEnumerable()
                                  Debug.WriteLine("Worker 1: " & value)
                              Next
                          End Sub)

edited Mar 16 '14 at 09:39

answered Mar 15 '14 at 11:48

dbasnett

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All I want is a basic working example to understand it before moving on. I get the same problems with all the tutorials I have tried – Henry Ing-Simmons Mar 16 '14 at 01:05
Thanks. Sorry I was working into the early hours and have been flitting between languages. Forget in my converting from C# tutorial to vb.net code that VB is awkwardly different to every other programming language. Problems with + rather than & – Henry Ing-Simmons Mar 16 '14 at 01:13

Basic BlockingCollection Producer Consumer in VB.NET

1 Answers1