PLZ HELP ME WITH Multithreading

[justme369]

Im going crazy with this i dont understand at all invokeee i want to run 2 subs at the same time when i click a button check 1 and check 2 are 2 subs when i click a button it calls sub pi which then calls the 2 forms but idk how.. this is the code for callin the 2 subs i want together to run

Public Sub pi() 
Dim thrMyThread As New System.Threading.Thread(AddressOf check2)
        thrMyThread.Start()
 
        Dim thrMyThread1 As New System.Threading.Thread(AddressOf check1)
        thrMyThread1.Start()End Sub 
 
Private Sub check2() 
textbox1.text="12" 
end sub 
 
Private Sub check1() 
textbox2.text="14" 
end sub

i figure it out, i just want to know if im doing it right...cuz apparently both are running at the same time..

this is the new part in the code

Dim thrMyThread As New System.Threading.Thread(AddressOf check2)
        thrMyThread.Start()

        Dim thrMyThread1 As New System.Threading.Thread(AddressOf check1)
        thrMyThread1.Start()End Sub

[jmcilhinney]

That code is successfully starting two new threads, but you should not be directly accessing TextBoxes on those threads. Generally speaking, anything that involves the UI needs to be done on the UI thread. You might start a new thread to perform some long-running task that intermittently invokes a method back on the UI thread to update the UI, e.g. display some text or update a ProgressBar.

[justme369]

the text boxes are an example....wat each thread does its run some codes for 2 separately datagrids

[justme369]

one thing i notice its that after each thread has finish...they both turn on 1 flag...in the main thread theres a code that checks for both flags..if theyre both on..then the datagrids adjust size,colums..and some buttons turn on..but it gives me an error saying i cant access a thread other then the other it started from...why am i getin this?

[justme369]

this is the error im getin when the 2 threads are done i call another thread and this appears


Cross-thread operation not valid: Control '' accessed from a thread other than the thread it was created on.

[justme369]

this is the code

1 button access the 2 diferent threads,

i want to execute sub thisisnext when thread mythread1 finish...but i dont know how because i keep getting an error saying i cannot acces one thread other then the thread it was creating from...so how can i do this

Private Sub pingipss_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles pingipss.Click
        cargaesto()
        staprog.Enabled = False
        stoprog.Enabled = False
        Ipnoreg.Enabled = False
        bck.Enabled = False
        mensaje = True
        If DataGridView1.Visible = False Then
            DataGridView1.Visible = True
            guardaripsactivas.Visible = True
            DataGridView2.Visible = False
            guardaipnoreg.Visible = False
            inventario.Visible = True
        End If
        
        PictureBox1.Visible = True
        DataGridView2.Rows.Clear()
        pingipss.Enabled = False
        cncel.Enabled = True
        guardaripsactivas.Enabled = False
        DataGridView2.Visible = False
 
        MyThread1 = New Thread(New ThreadStart(AddressOf thischecck))
        MyThread2 = New Thread(New ThreadStart(AddressOf thischecck2))
        MyThread1.Start()
        MyThread2.Start()
 
    End Sub
 
 
    Private Sub thischecck()
        Dim found As Boolean = True
        Dim macfound As Boolean
        Dim num1 As String
        Dim num2 As String
        Dim num01 As String
        Dim num02 As String
        Dim hello As String
        Dim sum As Integer
        Dim dom As String
 
 
        For sum = 0 ip28.Rows.Count - 1
            hello = ip28.Rows.Item(sum).Cells.Item(1).Value  ''this checks the ip of row 2 cell 2
 
 
           
            Try
                If My.Computer.Network.Ping(hello, 300) Then    ''this will ping the ip address and return true or false
 
                    ip28.Rows.Item(sum).Cells.Item(2).Value = "ON" '' this checks or not the checkbox for true or false
                    ip28.Rows.Item(sum).Cells.Item(3).Value = "-"
                                        For ver = 0 To inventario.Rows.Count - 1
 
                            If inventario.Rows.Item(ver).Cells.Item(1).Value Is DBNull.Value Then
                                num2 = "0"
                            Else
                                num2 = inventario.Rows.Item(ver).Cells.Item(1).Value 'ip
                            End If
 
                            If inventario.Rows.Item(ver).Cells.Item(7).Value Is DBNull.Value Then
                                num02 = "0"
                            Else
                                num02 = inventario.Rows.Item(ver).Cells.Item(7).Value 'mac
                            End If
                            If num1 = num2 Then
                                If num01 = num02 Then
                                    found = True
                                    macfound = True
                                    ip28.Rows.Item(sum).Cells.Item(7).Value = "YES"
                                    inventario.Rows.Item(ver).Cells.Item(0).Value = "YES"
                                    inventario.Rows.Item(ver).Cells.Item(4).Value = (DataGridView1.Rows.Item(sum).Cells.Item(6).Value)
                                    Exit For
                                Else
                                    found = True
                                    macfound = False
                                    ip28.Rows.Item(sum).Cells.Item(8).Value = "YES"
                                    inventario.Rows.Item(ver).Cells.Item(0).Value = "YES"
                                                        ip28.Rows.Item(sum).Cells.Item(7).Value = "YES But Different MAC "
                                    Exit For
                                End If
                            Else
                                found = False
                            End If
                        Next
                If found = False Then
                        ip28.Rows.Item(sum).Cells.Item(7).Value = "Not Found"
                    End If
Dim hi As String
                    SyncLock DataGridView1
                        For oki = 0 To DataGridView1.Rows.Count - 1
                            hi1 = DataGridView1.Rows.Item(oki).Cells.Item(1).Value
                            If hi = hi Then
                                DataGridView1.Rows.Item(oki).Cells.Item(2).Value = ip28.Rows.Item(sumadoe).Cells.Item(2).Value
                                DataGridView1.Rows.Item(oki).Cells.Item(3).Value = ip28.Rows.Item(sumadoe).Cells.Item(3).Value
                               Exit For
                            End If
                        Next
                    End SyncLock
                End If
            Catch ex As Exception
                Debug.WriteLine(ex.Source)
            End Try
            My.Application.DoEvents()
            found = True
            Next
end sub
 
 
Private Sub thischecck2()
        Dim found1 As Boolean = True
        Dim macfind As Boolean
        Dim no1 As String
        Dim no2 As String
        Dim no01 As String
        Dim no02 As String
        Dim hi As String
        Dim sumadoe As Integer
        Dim dmnio1 As String
 
 
        For sumadoe = 0 To 100
            hi = ip42.Rows.Item(sumadoe).Cells.Item(1).Value  ''this checks the ip of row 2 cell 2
            Try
                If My.Computer.Network.Ping(hi, 300) Then    ''this will ping the ip address and return true or false
                    ip42.Rows.Item(sumadoe).Cells.Item(2).Value = "ON" '' this checks or not the checkbox for true or false
                    ip42.Rows.Item(sumadoe).Cells.Item(3).Value = "-"
                        For ver = 0 To inventario.Rows.Count - 1
                            If inventario.Rows.Item(ver).Cells.Item(1).Value Is DBNull.Value Then
                                no2 = "0"
                            Else
                                no2 = inventario.Rows.Item(ver).Cells.Item(1).Value 'ip
                            End If
                            If inventario.Rows.Item(ver).Cells.Item(7).Value Is DBNull.Value Then
                                no02 = "0"
                            Else
                                no02 = inventario.Rows.Item(ver).Cells.Item(7).Value 'mac
                            End If
 
                            If no1 = no2 Then
                                If no01 = no02 Then
                                    found1 = True
                                    macfind = True
                                    ip42.Rows.Item(sumadoe).Cells.Item(7).Value = "YES"
                                    inventario.Rows.Item(ver).Cells.Item(0).Value = "YES"
                                    inventario.Rows.Item(ver).Cells.Item(4).Value = (ip42.Rows.Item(sumadoe).Cells.Item(6).Value)
                                    Exit For
                                Else
                                    found1 = True
                                    macfind = False
                                    ip42.Rows.Item(sumadoe).Cells.Item(8).Value = "YES"
                                    inventario.Rows.Item(ver).Cells.Item(0).Value = "YES"
                                                                       ip42.Rows.Item(sumadoe).Cells.Item(7).Value = "YES But Different MAC "
                                    Exit For
                                End If
                            Else
                                found1 = False
                            End If
                        Next
               
                    If found1 = False Then
                        ip42.Rows.Item(sumadoe).Cells.Item(7).Value = "Not found"
                    End If
 
                   Dim hi1 As String
                    SyncLock DataGridView1
                        For oki = 0 To DataGridView1.Rows.Count - 1
                            hi1 = DataGridView1.Rows.Item(oki).Cells.Item(1).Value
                            If hi1 = hi Then
                                DataGridView1.Rows.Item(oki).Cells.Item(2).Value = ip42.Rows.Item(sumadoe).Cells.Item(2).Value
                                DataGridView1.Rows.Item(oki).Cells.Item(3).Value = ip42.Rows.Item(sumadoe).Cells.Item(3).Value
                       
                                Exit For
                            End If
                        Next
                    End SyncLock
                
                End If
            Catch ex As Exception
                Debug.WriteLine(ex.Source)
            End Try
            My.Application.DoEvents()
            found1 = True
                Next
               flagi2 = True
    End Sub   
 
public sub thisisnext()
 
        pingipss.Enabled = True
        DataGridView1.AutoResizeColumn(1, DataGridViewAutoSizeColumnMode.AllCells)
        DataGridView1.AutoResizeColumn(2, DataGridViewAutoSizeColumnMode.AllCells)
        inventario.AutoResizeColumn(0, DataGridViewAutoSizeColumnMode.AllCells)
        inventario.AutoResizeColumn(1, DataGridViewAutoSizeColumnMode.AllCells)
   
        If mensaje = True Then
            MsgBox("El en Linea")
        End If
        If parado = True Then
            MsgBox("ElCancelado")
        End If
        PictureBox1.Visible = False
        pingipss.Enabled = True
        cncel.Enabled = False
        guardaripsactivas.Enabled = True
        guardaripsactivas.Visible = True
           staprog.Enabled = True
        bck.Enabled = True
 
             Ipnoreg.Enabled = True
        stoprog.Enabled = True
        Ipnoreg.Visible = True
 
    End Sub

[techgnome]

You're getting the error because you're accessing UI elements from your secondary threads... as jmc explained in post #2...

what is ip28 and ip42?

-tg

[justme369]

there are datagrids

[justme369]

i sort of knew it had something to do with wat jmc explained but how can i solve it?

since the code for both threads are really long i cut some code from both threads...

my interest its how to perform an action (RUN THE SUB thisisnext()) once both threads are finish

[techgnome]

use background workers... put your subs in the doWork events... in the completed event, set your flags... then check the flags, and if both are set, call your other sub.

I'm a little surprised that your code even works... if ip28 is a DGV, you should be getting errors the first time you access it about cross threading... you can't (or shouldn't) be able to access the UI from a non-UI thread......

-tg

[justme369]

how can i place the subs in the do work

Private Sub BackgroundWorker1_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
public check ()
end sub

public check1 ()
end sub
end sub

[justme369]

or u mean i call the threads in the do work?

[justme369]

tell me if this is ok to do..


i run only one sub in the background worker...this sub its the one that takes longer to finish ...

and when i click button 1
i run the background worker along 2 more threads...that finish really fast..

so when background worker finish basically all the others are done..

so the do work runs my other sub..

its this programatically correct to do..

i did it and no errors...i just want to know if this way its GOOD ONE

[kareninstructor]

As stated by jmcilhinney in his reply you normally not update the UI in the secondary thread but if you must you need to use Threading.SynchronizationContext in tangent with Threading.SendOrPostCallback which gets ugly fast. The attached demo uses two threads where the secondary thread updates the first thread, the UI.

The project is VS2008

[jmcilhinney]

As stated by jmcilhinney in his reply you normally not update the UI in the secondary thread but if you must you need to use Threading.SynchronizationContext in tangent with Threading.SendOrPostCallback which gets ugly fast. The attached demo uses two threads where the secondary thread updates the first thread, the UI.

The project is VS2008

That's not really accurate. The SynchronizationContext is not a way to update the UI from a secondary thread. It is a way to marshal a method call to a specific thread, usually the UI thread, in order to execute a method on that thread. Calling the Send or Post method of a SynchronizationContext is equivalent to calling Invoke or BeginInvoke on a control: they both marshal a method call to the thread that owns the object you call the method on.

If you check out my CodeBank submission on Accessing Controls From Worker Threads it uses the ISynchronizeInvoke implementation of the Control class in most examples, i.e. the InvokeRequired property and the Invoke method, but, towards the end, I've re-implemented one of the examples using the SynchronizationContext. That demonstrates the equivalence between the two.