运行一个功能的多线程线程VB.net

Question

I am having a weird issue.

My checkedlistbox has 3 items in it. I check all of the items and click on my button. The button should create the equal number of threads (as the checked items number) and give the index of the checkeditems to a function. The function gives out the checkeditems in the console.

Public Class Form1
    Private ThreadList As New List(Of Threading.Thread)

    Private Sub MeineFunktion(ByVal username As String)
        Threading.Thread.Sleep(2000)
        Console.WriteLine(username)
        'Debug.Print(username)
    End Sub

 Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim indexChecked As Integer


        For Each indexChecked In CheckedListBox1.CheckedIndices



            Dim t As Threading.Thread = New Threading.Thread(Sub() MeineFunktion(indexChecked.ToString))
            ThreadList.Add(t)
            t.Start()


        Next

    End Sub
End Class

The issue is, the console always gives out

1, 1, 2

Instead of

0, 1, 2

Why is the first item always ignored?

What I tried so far

Changing the byval username as INTEGER, and doing sneding the value like this

Dim t As Threading.Thread = New Threading.Thread(Sub() MeineFunktion(indexChecked))

And still encountered the same issue. Either it has something to do with my threadings, or with the function which does the console writeline (I tried debug print as well).

I can't pinpoint what is causing the issue

Answer 1

Each thread needs some time to be created and start running. It seems you are changing username before the thread can use it. Try to add a small delay just after each thread start:

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim indexChecked As Integer
    For Each indexChecked In CheckedListBox1.CheckedIndices
        Dim t As Threading.Thread = New Threading.Thread(Sub() MeineFunktion(indexChecked.ToString))
        ThreadList.Add(t)
        t.Start()
        Do
            Threading.Thread.Sleep(10)
        Loop Until t.IsAlive
    Next
End Sub