This is my code:
For i As Integer = 0 to 20
mythread = New System.Threading.Thread(AddressOf myfunction)
mythread.Start()
Next
I want to kill all threads that are running myfunction()
I tried:
For Each hello123 As System.Threading.Thread(AddressOf myfunction)
thread.abort(hello123)
Next
But came up with an error (on AddressOf):
Array bounds cannot appear in type specifiers.
To stop a function, we need to define a boolean. Then, function needs to be inside do while our_boolean = true loop. Stop button's code must have our_boolean = false, so when it's pressed, do while loop is gonna end immediately.
It looks something like this:
Do While potato = True
'code
Loop
When stop button is pressed, loop is gonna stop immediately because potato is set to false. Then when we want to continue running the code, we just need to set potato to true and call function.
Related
Have strange behaviour in my task which is not finishing. I use this all the time but i suppose its because sub i am passing to it is iteracting with form - changing selection and refreshing some listbox probably therefore its stack there but i am not sure. Lets see the code:
This is the sub i want to be run in task:
Public Sub UnselectExistingConnectionsItems()
Dim SentenceId, SubSubKategorieId, SubSectionId As Integer
SubSectionId = CbSubSections.SelectedValue 'combobox
If WithSubSubkategorie = SubSubKategorieEnum.Without Then
SubSubKategorieId = 0
Else
SubSubKategorieId = CbSubSubKategorie.SelectedValue 'combobox
End If
Unselect:
For i As Integer = 0 To LB_Sentences.SelectedItems.Count - 1
Dim sKey As ListBoxItem
sKey = LB_Sentences.SelectedItems(i)
SentenceId = HtmlDescription.HtmlSentence.GetSentenceIdByName(sKey.Text)
If HtmlDescription.HtmlSubSubSections_Sentences.CheckIfConnectionAlreadyExist(SentenceId, SubSectionId, SubSubKategorieId) Then
sKey.IsSelected = False
LB_Sentences.Refresh()
GoTo Unselect
End If
Next
End Sub
i put it to Task like this:
Dim pic As New FrmCircularProgress(eCircularProgressType.Line)
Dim work As Task = Task.Factory.StartNew(Sub()
'--Run lenghty task UnselectExistingConnectionsItems()
'--Close form once done (on GUI thread)
pic.Invoke(New Action(Sub() pic.StopCircular()))
pic.Invoke(New Action(Sub() pic.Close()))
End Sub)
'--Show the form
pic.ShowDialog()
Task.WaitAll(work)
and FrmCircularProgress is just form ( i use it almost everywhere where i have to user wait and its working besides this particural case):
Public Class FrmCircularProgress
Sub New(progressType As DevComponents.DotNetBar.eCircularProgressType)
InitializeComponent()
CircularProgress1.ProgressBarType = progressType
StartCircular()
End Sub
Public Sub StartCircular()
Me.CircularProgress1.IsRunning = True
End Sub
Public Sub StopCircular()
Me.CircularProgress1.IsRunning = False
End Sub
End Class
what could be wrong? is it because procedure is interacting with listbox and combobxes? If so how to fix that, i read something about invoking listbox and comboboxes but have no idea how to fix that.
EDIT:
I think besides those lines:
sKey.IsSelected = False
LB_Sentences.Refresh()
I have to make those:
LB_Sentences.Invoke(Sub() sKey.IsSelected = False
End Sub)
LB_Sentences.Invoke(Sub() LB_Sentences.Refresh()
End Sub)
because i am in diffrent thread. Somehow i dont know how to convert those lines:
SubSectionId = CbSubSections.SelectedValue
SubSubKategorieId = CbSubSubKategorie.SelectedValue
probably loop also have to be invoked. Waiting your help.
There is a rule that says "The only thread that can modify a control in a window is the thread that created the window". Any other thread trying to modify something in the window will generate a cross-thread call exception.
So in your first edit you got it right, you have to invoke the functions.
However, this doesn't fix your problem of not finishing Task.
I believe that doing sKey.IsSelected = False does not unselect anything in your ListBox, therefore causing an infinite loop... Also that Goto statement is very bad programming habits and should not be used. There is always another solution that will make your code easier to debug/maintain/read...
ListBoxItem is not a type that exists in the .Net Framework. So either you created that class either it's something else (and I don't know what...)
What you can do to solve your problem is :
Get the indices of all selected items in a list
Run through your list, and check if they should be selected :
If they should be selected, do nothing
if they shouldn't, unselect them.
Which makes your code like this (and you remove that ugly Label and Goto that you don't want in your code)...
Public Sub UnselectExistingConnectionsItems()
Dim SentenceId, SubSubKategorieId, SubSectionId As Integer
SubSectionId = CbSubSections.SelectedValue 'combobox
If WithSubSubkategorie = SubSubKategorieEnum.Without Then
SubSubKategorieId = 0
Else
SubSubKategorieId = CbSubSubKategorie.SelectedValue 'combobox
End If
'We create an array to remind our initial selection
Dim sel = New Integer(LB_Sentences.SelectedItems.Count - 1) {}
LB_Sentences.SelectedIndices.CopyTo(sel, 0)
For i = 0 To sel.Length - 1
Dim sKey As ListBoxItem
'We get our selected item
sKey = LB_Sentences(sel(i))
SentenceId = HtmlDescription.HtmlSentence.GetSentenceIdByName(sKey.Text)
If HtmlDescription.HtmlSubSubSections_Sentences.CheckIfConnectionAlreadyExist(SentenceId, SubSectionId, SubSubKategorieId) Then
'We must remove it from the selection
LB_Sentences.Invoke(Sub() LB_Sentences.SelectedItems.Remove(sKey))
End If
Next
'We do the Refresh at the end so we gain some process time...
LB_Sentences.Invoke(Sub() LB_Sentences.Refresh())
End Sub
Can someone show/tell me where I'm steering wrong with this? I am running a second thread in my application where all it does is read values from registers in a motion controller and then constantly updates those values to the appropriate fields on my UI every 100ms. When I disconnect the controller (ie...Ethernet cable disconnected, so lost comms), I want to destroy/terminate the thread (thread1) completely. When I reconnect the Ethernet cable, I click a button on my UI to reestablish comms to the controller, and execute Runthread() Sub. That is when I want to recreate the thread and start it. However, when debugging this part of the code, it appears that the thread (thread1) is never destroyed even though I have verified that the code does get to that line (Case 1) and execute it. After comms is re-established, the code goes right to Case 3 and starts thread1, where I would expect it to jump to Case 2 and recreate the thread.
Public Class frmMain
Private RMC As RMCLink
Public thread1 As System.Threading.Thread = New System.Threading.Thread(AddressOf ReadRegisters)
Private Sub RunThread()
Dim conditions As Integer
If RMC.IsConnected(PingType.Ping) = False And thread1 IsNot Nothing Then
conditions = 1
ElseIf RMC.IsConnected(PingType.Ping) = True And thread1 Is Nothing Then
conditions = 2
ElseIf RMC.IsConnected(PingType.Ping) = True And thread1 IsNot Nothing Then
conditions = 3
End If
Select Case conditions
Case 1
Thread.Sleep(100)
thread1.Abort()
Case 2
Dim thread1 As System.Threading.Thread = New System.Threading.Thread(AddressOf ReadRegisters)
thread1.Start()
Case 3
thread1.Start()
End Select
End Sub
The documentation (https://msdn.microsoft.com/en-us/library/system.threading.thread.abort(v=vs.110).aspx) states that it usually terminates the thread, but as you've found this doesn't always happen.
One way to accomplish this (I'm sure there are others), is to create a public PleaseDie property that your thread's subroutine(s) check periodically, and if that property is set to True, then exit the subroutines within the thread. Before the thread is started, you'll of course have to reset PleaseDie to False.
I have written in vb.net for progress bar. I am thinking of there is a better way than this.
Here is what my code is :
Private Function ImportDataFiles(ByRef pobjDataLoadDTO As DataLoadDTO) As Boolean
Try
lblStatus.Visible = True
lblStatus.Text = ""
myProgressBar.Visible = True
myProgressBar.Value = 0
For Each drRow As ImportData.TRow In pobjDataLoadDTO.FileInfo.Select("categ_code = 'abc'")
If pobjDataLoadDTO.FileTimes.ContainsKey(drRow.KEY_CODE) AndAlso _
pobjDataLoadDTO.FileTimes(drRow.KEY_CODE) > pobjDataLoadDTO.UploadTimes(drRow.KEY_CODE) Then
pobjDataLoadDTO.DestinationTablename = drRow.KEY_CODE
If mobjDataLoadBO.ImportDataFiles(pobjDataLoadDTO) Then
drRow.DATA_TXT = mobjCommonBO.ONow.ToString
End If
End If
lblStatus.Text = drRow.KEY_CODE.Trim & "is loading...."
lblStatus.Refresh()
myProgressBar.PerformStep()
lblStatus.Refresh()
Next
Return True
Catch ex As Exception
Return False
End Try
End Function
Right now It is working, But I want to use more efficient way, like using Backgroundworkerprocess...etc., Any Ideas on this one?
Since your function runs in main thread, I assume your application is freezing and not very smooth while upload in progress.
1 - Drop Backgroundworker control on the form
2 - set "reportProgress" property of the worker to "True"
3 - Move your loop code into "DoWork" event of the worker control. And call worker.RunWorkerAsync. You can pass needed arguments to it
4- the code that refreshes progress bar move into "ProgressChange" event of the worker. This is important as you can't call control from worker thread. and ProgressChange is running in the main thread. You can also delete "Refresh" method call. That will not be needed anymore. Every time you want to refresh the progress bar call "ReportProgress" method of the worker
5-Use "RunWorkerCompleted" worker event, to do your clean up, and hide your progress bar
Its also might be a good idea to check if worker is already working before initiating, like
If worker.IsBusy Then
If worker.CancellationPending = False Then
worker.CancelAsync()
End If
Exit Sub
End If
Is there some way to have a 'listener' of sorts to listen for a button click in the middle of code? There are certain scenarios where I won't have to wait for the code to complete before I can exit the functions but I cannot seem to find a way to see if the button was clicked other than throwing a ton of if checks throughout the function calls which doesn't seem very efficient to me.
This code runs on the thread, different from your main application
private function LongRunningFunction()
Din canceled as boolean = false ' to make sure it is canceled while in the loop
' this is very long loop
For i as integer = 0 to 100000
If _cancelExecution Then
canceled = true
Exit For
End If
' your code runs here
.........
Next
If canceled Then
' Wrap up this thread, clean up stuff, etc
End If
.......................
End Function
On the main thread, when button is clicked _cancelExecution is set to true
The BackGroundWorker has this mechanism built-in already
I have a simple code that looks up a text file, reads the line of text, splits the string by semi-colons and then posts the results.
After it has done this, I have created a really simple while loop to waste 10 seconds before going for it again.... here is the code:
Private Sub checkTemps()
While Abort = False
Try
fileReader = New StreamReader(directory.Text & "currentTemp.dat")
rawData = fileReader.ReadLine()
fileReader.Close()
Dim dataArray() As String
dataArray = rawData.Split(";")
updateOutput("1", dataArray(0), dataArray(1))
updateOutput("2", dataArray(2), dataArray(3))
updateOutput("3", dataArray(4), dataArray(5))
updateOutput("4", dataArray(6), dataArray(7))
stpWatch.Start()
While stpWatch.Elapsed.Seconds < 10 And Abort = False
pollInterval(stpWatch.ElapsedMilliseconds)
End While
stpWatch.Stop()
stpWatch.Reset()
Catch ex As Exception
msgbox("oops!")
End Try
End While
closeOnAbort()
End Sub
But when it gets to the "time-wasting" loop - it seems to slow the whole application down? And I can't work out why!
So a couple of questions... is there a better way to do all this? and second - can anyone spot a problem?
All the other commands seem to run fine - there isn't much else to this app. I have another program that updates the dat file with the values, this is simply a client side app to output the temperatures.
Any help would be appreciated.
Andrew
More info:
I should explain what the pollInterval sub does!
Private Delegate Sub pollIntervalDelegate(ByVal value As Integer)
Private Sub pollInterval(ByVal value As Integer)
If Me.InvokeRequired Then
Dim upbd As New pollIntervalDelegate(AddressOf pollInterval)
Me.Invoke(upbd, New Object() {value})
Else
ProgressBar1.Value = value
End If
End Sub
Your loop is a very tight loop continually calling pollInterval. This will tie up the application until the loop condition is met.
You should use the Sleep method to pause this thread for the required amount of time.
If you want to show the progress (as per your update) you could put the Sleep into the loop and sleep for 1 second (or half a second?) at a time:
While stpWatch.Elapsed.Seconds < 10 And Abort = False
Sleep(1000) <-- NOT 100% sure of the syntax here,
but the time is specified in milliseconds
pollInterval(stpWatch.ElapsedMilliseconds)
End While
You should go with
System.Threading.Thread.Sleep(TimeSpan.FromSeconds(10).TotalMilliseconds);