[RESOLVED] Run same class in multiple threads?

[Thildemar]

I am trying to create an app that will ping all IP's in a subnet and if they are online attempt to gather WMI information from them. To do this I would like to check multiple IPs at once as one at a time would take ages. So I am trying to do as follows

sub btnclcick
Dim T1 As Thread
 
        For i = 1 To 255
 
            T1 = New Thread(AddressOf Collect)
            T1.IsBackground = True
            T1.Start()
 
        Next
end sub
 
private sub collect()
'ping and get WMI
end sub

Problem is each time the thread is restarted it starts the sub over before it can do anyting, how can I get multiple threads to open that same sub and all work at once?

[sevenhalo]

is this 2.0?

[ComputerJy]

Use an array of Threads instead of using the same thread over and over

[Thildemar]

VB.NET 2005 .NET framework 2.0

ok tried this:

sub btnclcick
Dim T1() As Thread
 
        For i = 1 To 255
 
            T1(i) = New Thread(AddressOf Collect)
            T1(i).IsBackground = True
            T1(i).Start()
 
        Next
end sub
 
private sub collect()
'ping and get WMI
end sub

and i get "Object reference not set to an instance of an object." on

T1(i) = New Thread(AddressOf Collect)

[mpdeglau]

2 things

1. You need to inialize the size of the array

Dim t1(254) as Thread

2. Arrays in .Net are 0 based, so your loop will go from 0 - 254

[Thildemar]

Ok that fixed that problem, but still same initial problem, each thread seems to cancel what the last was doing out in the sub.

so when debugging if I step through it might get to the 2nd line of code in the sub and then a new thread will pick up and start over the sub. The first thread never seems to finish the sub...

[techgnome]

I think .... not sure mind you, but I think the problem is in your delegate.... you are spawing a thread of a localized function.... you may want to move that into its own class... create a new instance of it, then tie that off in it's own thread..... You'll need to make sure you have somekinf of callback so that you know when it's done.

In each case Collect has the same address... it needs to have it's own address for each thread you spawn off. Moving it into it's own class and creating an instance of that class should solve that problem.

-tg

[Thildemar]

That sounds about right, but I'm fairly new to the use of a lot of this stuff. what would I need to move into a class (just the collect sub I'm assuming?) and then how do I spawn an instance of that class?

[ComputerJy]

Here is a sample of what your code should look like

Public Class MainClass
    Private Threads(256) As Threading.Thread
    Private PingObjects(256) As PingClass
    Private Sub MySub()
        For I As Integer = 0 To 255
            PingObjects(I) = New PingClass
            Threads(I) = New Threading.Thread(AddressOf PingObjects(I).collect)
            Threads(I).IsBackground = True
            Threads(I).Start()
        Next
    End Sub
End Class
Public Class PingClass
    Public Sub collect()
 
    End Sub
End Class

[Thildemar]

now on:

Threads(I) = New Threading.Thread(AddressOf PingObjects(I).collect)

I get
"Delegate to an instance method cannot have null 'this'."

[Thildemar]

Ok fixed that error, something was screwed within my project file. Moved code to new project and no more error...odd.

Now the program throws no errors, but the thread does not seem to do anything, I made a test sub to have the thread simple chane the number in a text box and the text box stays blank...any new ideas?

[Thildemar]

So threads can not modify values within another class eh? Any ideas on how to get my threads to output values to my main form?

[sevenhalo]

This will update your form as long as the thread belongs to the same class (according to msdn, it's also the thread safe way):

Private thrd As New Threading.Thread(AddressOf Gonuts)
    Delegate Sub MyDel(ByVal [int] As Integer)
 
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        thrd.Start()
    End Sub
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        thrd.Abort()
    End Sub
 
    Private Sub UpdateLabel(ByVal [int] As Int32)
        If Me.Label1.InvokeRequired Then
            Dim d As New MyDel(AddressOf UpdateLabel)
            Me.Invoke(d, New Object() {[int]})
        Else
            Me.Label1.Text = [int].ToString
        End If
    End Sub
 
    Public Sub Gonuts()
        Dim int As Int32 = 0
        While Threading.Thread.CurrentThread.ThreadState <> Threading.ThreadState.Stopped And _
            Threading.Thread.CurrentThread.ThreadState <> Threading.ThreadState.Aborted
            int += 1
            Me.UpdateLabel(int)
        End While
    End Sub

I'm sure there's a way with reflection for the thread to determine the property name of the parent object so that you can modify the form via seperate object/thread. I'll play a little and see if I can get it to work.

[Thildemar]

The problem has changed soo much from the original I am going to begin a new thread... Thanks for all the help.