Task is running and cannot be finished - vb.net

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

Related

Why is my invoke adding 10 seconds onto grid loading time?

I've attempted to add a method invoker to stop my error log being spammed with "Bounds cannot be changed while locked."
This has solved my issue, however...It has added an extra 10 seconds onto the loading time of my RadGridView.
I looked at https://www.telerik.com/forums/bounds-cannot-be-changed-while-locked to setup my invoker but there isn't much else that I can see to help with my issue.
I've attached a sample of my code below, any help would be appreciated.
Private Sub bgw_initialLoad_DoWork(sender As Object, e As DoWorkEventArgs)
Try
liveDS = New DataSet
Dim dsholder As DataSet = GetDataFromSQL("LoadData")
Dim dt1 As DataTable = dsholder.Tables(0)
Dim dt_1 As DataTable = dt1.Copy()
dt_1.TableName = "Customer"
liveDS.Tables.Add(dt_1)
Dim dt2 As DataTable = dsholder.Tables(1)
Dim dt_2 As DataTable = dt2.Copy()
dt_2.TableName = "Orders"
liveDS.Tables.Add(dt_2)
Dim dt3 As DataTable = dsholder.Tables(2)
Dim dt_3 As DataTable = dt3.Copy()
dt_3.TableName = "OrderLine"
liveDS.Tables.Add(dt_3)
If RadGridView.InvokeRequired Then
RadGridView.Invoke(New MethodInvoker(AddressOf SetupDataSources))
Else
SetupDataSources()
End If
Catch ex As Exception
sendCaughtError(ex)
End Try
End Sub
Private Sub SetupDataSources()
If liveDS.Tables.Count > 1 Then
RadGridView.DataSource = liveDS.Tables("Customer")
liveOrdersTemplate.DataSource = liveDS.Tables("Orders")
liveOrdersTemplate2.DataSource = liveDS.Tables("OrderLine")
End If
End Sub
Private Sub bgw_initialLoad_RunWorkerCompleted(sender As Object, e As RunWorkerCompletedEventArgs)
Try
RadGridView.DataSource = liveDS.Tables("Customer")
Dim template As New GridViewTemplate()
template.DataSource = liveDS.Tables("Orders")
RadGridView.MasterTemplate.Templates.Add(template)
Dim template2 As New GridViewTemplate()
template2.DataSource = liveDS.Tables("OrderLine")
RadGridView.Templates(0).Templates.Add(template2)
Dim relation As New GridViewRelation(RadGridView.MasterTemplate)
relation.ChildTemplate = template
relation.ParentColumnNames.Add("Invoice Customer")
relation.ChildColumnNames.Add("InvoiceCode")
RadGridView.Relations.Add(relation)
Dim relation2 As New GridViewRelation(RadGridView.Templates(0))
relation2.ChildTemplate = template2
relation2.ParentColumnNames.Add("OrderNo")
relation2.ChildColumnNames.Add("OrderNo")
RadGridView.Relations.Add(relation2)
FormatGrid()
SplitContainer2.Panel1.Enabled = True
SplitContainer1.Panel2.Enabled = True
refreshMainGrid()
HideLoadingGif()
Catch ex As Exception
sendCaughtError(ex)
End Try
End Sub
Debugging threads can be hard, trust me. This isn't a "real" answer, but a bunch of tips which may help - which is what I hope will happen.
There are dedicated windows in the debug menu which may help. I started with this webpage when I was wondering what was happening to my application and why it wasn't obvious why it was happening.
Also, while your parallel thread is running, it may "silent crash" if your IDE isn't set to pause on every crash, in which case it won't return a value but will just stay silent. Make sure at least these options are set:
And don't forget to show this window while debugging: (previous image showed Threads and Call stack instead, while they are good to have around while debugging it's the parallel stacks which I was going for)
One last thing: such a big delay may be database related. I'm not saying that it is, but you should be aware of the possibility.
Now the following isn't part of the answer per se, but is more of a friendly advice: put your invoke logic in SetupDataSources() instead, this way wherever it's called you'll be thread safe. Like this:
Private Sub SetupDataSources()
If RadGridView.InvokeRequired Then
RadGridView.Invoke(Sub() SetupDataSources())
End If
If liveDS.Tables.Count > 1 Then
RadGridView.DataSource = liveDS.Tables("Customer")
liveOrdersTemplate.DataSource = liveDS.Tables("Orders")
liveOrdersTemplate2.DataSource = liveDS.Tables("OrderLine")
End If
End Sub
Best of luck... you might need some ;)

How do I create a new form instance whose name I have in a string? [duplicate]

Code to create new form instance of a closed form using form name
I want to replace the long Select Case list with a variable.
Full code of module
In Access 2010 I have a VBA function that opens a new instance of a form when given a string containing the form's name. By adding a form variable "frm" to a collection:
mcolFormInstances.Add Item:=frm, Key:=CStr(frm.Hwnd)
The only way I can figure out to open "frm" is with a Select Case statement that I've manually entered.
Select Case strFormName
Case "frmCustomer"
Set frm = New Form_frmCustomer
Case "frmProduct"
Set frm = New Form_frmProduct
... etc ... !
End Select
I want it to do it automatically, somewhat like this (although this doesn't work):
Set frm = New Eval("Form_" & strFormName)
Or through some code:
For Each obj In CurrentProject.AllForms 'or AllModules, neither work
If obj.Name = strFormName Then
Set FormObject = obj.AccessClassObject 'or something
End If
Next
Set frm = New FormObject
I just want to avoid listing out every single form in my project and having to keep the list updated as new forms are added.
I've also done some testing of my own and some reading online about this. As near as I can tell, it isn't possible to create a new form object and set it to an instance of an existing form using a string that represents the name of that form without using DoCmd.OpenForm.
In other words, unless someone else can prove me wrong, what you are trying to do cannot be done.
I think you are looking for something like this MS-Access 2010 function. (The GetForm sub is just for testing):
Function SelectForm(ByVal FormName As String, ByRef FormExists As Boolean) As Form
For Each f In Application.Forms
If f.Name = FormName Then
Set SelectForm = f
FormExists = True
Exit Function
End If
Next
FormExists = False
End Function
Sub GetForm(ByVal FormName As String)
Dim f As New Form
Dim FormExists As Boolean
Set f = SelectForm(FormName, FormExists)
If FormExists Then
MsgBox ("Form Found: " & f.Caption)
Else
MsgBox ("Form '" & FormName & "' not found.")
End If
End Sub
Here's an ugly hack I found:
DoCmd.SelectObject <acObjectType>, <YourObjectsName>, True
DoCmd.RunCommand acCmdNewObjectForm
The RunCommand step doesn't give you programmatic control of the object, you'll have to Dim a Form variable and Set using Forms.Item(). I usually close the form after DoCmd.RunCommand, then DoCmd.Rename with something useful (my users don't like Form1, Form2, etc.).
Hope that helps.

Secondary thread causes "Application has stopped working" crashes even when invoking

I have an application which has a form with a DataGridView bound to a BindingSource, which is bound to a DataTable:
bsList.DataSource = dsData
bsList.DataMember = "List"
dgvList.DataSource = bsList
The underlying data which populates dsData.Tables("List") can change whilst the user is working so to combat this I have a background thread which routinely checks the database for changes and updates dsData.Tables("List"). It also changes the colour of any row where another user is currently working.
However, users report that when this background updating functionality is enabled the application routinely CTDs with no application error message. I have been unable to reproduce this and my attempt to log the crashes via writing to a log file in Private Sub MyApplication_UnhandledException(sender As Object, e As UnhandledExceptionEventArgs) Handles Me.UnhandledException hasn't worked as the log file is never written to, suggesting this event is never triggered.
The thread is instantiated like this:
LiveUpdating = New Thread(AddressOf UpdateUserLocation) With {.IsBackground = True}
LiveUpdating.Start()
This is the UpdateUserLocation sub:
Public Sub UpdateUserLocation()
Do While My.Settings.customBackgroundUpdating = True And formLoaded = True
UserLocations.Clear()
dtUsers = CLS_USERS.GetUsersSequence(winUser)
dtProgress = DAC.GetProgress()
For Each CandRow As DataRow In dsHHData.Tables("List").Rows
Dim CandReadDate As Date
Dim CandRowNextRead As String = DBNull.Value.ToString
If Not (CandRow("NEXT READ").ToString = DBNull.Value.ToString) Then
If Date.TryParse(CandRow("NEXT READ").ToString, CandReadDate) Then
CandRowNextRead = CandReadDate.ToString("dd/MM/yyyy")
End If
End If
Dim CandRowSending As String = TryCast(CandRow("SENDING"), String)
Dim CandRowNotes As String = TryCast(CandRow("NOTES"), String)
For Each NewRow As DataRow In dtUsers.Rows
If CandRow("SQ").ToString = NewRow("SQ").ToString Then
UserLocations.Add(NewRow("SQ").ToString)
End If
Next
For Each ProgressRow As DataRow In dtProgress.Rows
If CandRow("SQ").ToString = ProgressRow("SQ").ToString Then
Dim NextReadDate As Date
Dim ProgressRowNextRead As String = DBNull.Value.ToString
If Not (ProgressRow("NEXT READ").ToString = DBNull.Value.ToString) Then
If Date.TryParse(ProgressRow("NEXT READ").ToString, NextReadDate) Then
ProgressRowNextRead = NextReadDate.ToString("dd/MM/yyyy")
End If
End If
Dim ProgressRowSending As String = TryCast(ProgressRow("SENDING"), String)
Dim ProgressRowNotes As String = TryCast(ProgressRow("NOTES"), String)
If CandRow("SQ").ToString = ProgressRow("SQ").ToString Then
If CandRowSending <> ProgressRowSending Then
BeginInvoke(New UpdateDataTableDelegate(AddressOf UpdateDataTableSending), CandRow, ProgressRowSending)
End If
If CandRowNextRead <> ProgressRowNextRead Then
BeginInvoke(New UpdateDataTableDelegate(AddressOf UpdateDataTableNextRead), CandRow, ProgressRowNextRead)
End If
If CandRowNotes <> ProgressRowNotes Then
BeginInvoke(New UpdateDataTableDelegate(AddressOf UpdateDataTableNotes), CandRow, ProgressRowNotes)
End If
End If
End If
Next
Next
dgv.BeginInvoke(
New MethodInvoker(
Sub()
For Each dgv_row As DataGridViewRow In dgv.Rows
If UserLocations.Contains(dgv_row.Cells("SQ").Value.ToString) Then
dgv.DefaultCellStyle.BackColor = My.Settings.customRowHighlight
Else
dgv.DefaultCellStyle.BackColor = Nothing
End If
Next
End Sub))
Thread.Sleep(My.Settings.customRefreshRate * 1000)
Loop
End Sub
The subs that do the DataTable update are like this:
Private Delegate Sub UpdateDataTableDelegate(ByVal CandRow As DataRow, ByVal ProgressRow As String)
Private Sub UpdateDataTableSending(ByVal CandRow As DataRow, ByVal ProgressRowSending As String)
CandRow("SENDING") = ProgressRowSending
End Sub
I know this is not the best way to handle a multi-user environment but the nature of this work requires that all people can access and see the same data. I could force them to refresh regularly but that seems very intrusive.
The crashes only occur when this thread is running and the crashes are regular (and not instant) but I cannot seem to reproduce them and the application is very stable otherwise.
There must be some cross-threading issue but I can't work how when all of the updates to the DataTable or DataGridView are done via a BeginInvoke on the main UI thread.
EDIT: I've just realised that even though I am doing the queries and most of the heavy lifting in the background thread, the updates are stilled called on the main UI thread which would lock the thread. This would be particularly noticeable if there were a lot of updates... Because each one is called individually.
If the UI lock up was long enough, and the user was clicking on stuff, would this cause Windows to treat the application as unresponsive and crash it? If so, is there a better way I could handle these updates?
Any help with resolving this would be enormously appreciated.

Why is my event handler firing two times?

I have a bunch of panels that I am adding to a single parent panel and I want to add event listeners to all of the panels but not until after they have all been added to the parent (becuase I don't want the event listeners firing each time a new panel gets added). So I am using the following code:
Dim temp_object As question_bar = Nothing
For Each q As Object In review_holder.Controls
If TypeOf q Is question_bar Then
temp_object = q
AddHandler temp_object.Resize, AddressOf temp_object.resize_me
End If
Next
For Each q As Object In review_holder.Controls
If TypeOf q Is question_bar Then
temp_object = q
temp_object.resize_me()
End If
Next
But I noticed that the resize_me() subroutine is getting fired twice for each control. I only want it to fire once. So I traced it out using this code
MsgBox((New System.Diagnostics.StackTrace).GetFrame(1).GetMethod.Name)
and I see that each time it gets called the calling methods are both this subroutine and _Lambda$_365. What the heck is that? How do I find out where that is coming from?
BTW, this is a winforms app using VS2012.
EDIT ------------------------------------------------------------------------
Public Sub resize_me()
MsgBox((New System.Diagnostics.StackTrace).GetFrame(1).GetMethod.Name)
If Me.minimized = True Then
Me.Height = 0
Exit Sub
End If
number_panel.Width = my_parent.number_width
number_text.Width = my_parent.number_width
number_separator.Left = number_panel.Right
question_panel.Left = number_separator.Right
question_panel.Width = question_panel.Parent.Width * initial_question_width + (question_padding * 2)
End Sub
Well changing size properties when you are inside a resize event could explain why your code is recalled again a second time. Usually I try to avoid this kind of situations but this is not always possible. In these cases then a global variable that acts as a flag to block the reentry could save the day
Dim insideResize As Boolean
Public Sub resize_me()
if insideResize = True Then
Exit Sub
End if
insideResize = True
Try
If Me.minimized = True Then
Me.Height = 0
Exit Sub
End If
number_panel.Width = my_parent.number_width
number_text.Width = my_parent.number_width
number_separator.Left = number_panel.Right
question_panel.Left = number_separator.Right
question_panel.Width = question_panel.Parent.Width * initial_question_width + (question_padding * 2)
Finally
insideResize = False
End Try
End Sub
To stay on the safe side with this patterns remember to always use a Try/Finally block to be sure that when you exit from the Resize event the global flag is correctly set back to false.

Update a label from a task

I'm trying to implement tasks in my program. I launch a task that will produce a log file, and after, I want to update the label to say "Log sucessfully saved".
Here is my code
Private Function Createlog(ByVal mylist As List(Of classTest))
Dim sw As New StreamWriter("log_list.log")
For index = 1 To mylist.Count - 1
sw.WriteLine(mylist(index).comments)
Next
sw.Close()
Try
Me.Invoke(UpdateLabel("Log sucessfully saved"))
Catch ex As Exception
End Try
Return 1
End Function
Private Function UpdateLabel(ByVal text As String)
Label1.Text = text
Return 1
End Function
I launch the task from the Main form in the Load() :
Dim tasktest = Task(Of Integer).Factory.StartNew(Function() Createlog(theList))
(I don't know if it is better to use the factory or declare as a task and then task.Start())
I have the error on the label update :
Cross-thread operation not valid: Control 'Label1' accessed from a thread
other than the thread it was created on.
Could you please explain why it doesn't work with the invoke method ? And do you have an alternative solution ?
Thanks for your help
First, UpdateLabel should be a Sub, not a Function. Second, this line is wrong:
Me.Invoke(UpdateLabel("Log sucessfully saved"))
Read it again. You are, in order, executing the UpdateLabel function, then passing the result of that function to Me.Invoke (if you used Sub instead of Function, the compiler should have warned you about the error).
This doesn't raise any compiler errors because a Function declared without As [Type] is defaulted to As Object, that can be cast to anything. It should be:
Me.Invoke(Sub()
UpdateLabel("Log sucessfully saved")
End Sub)
To simplify, your code can be rewritten like this:
Private Sub Createlog(ByVal mylist As List(Of classTest))
Dim sw As New StreamWriter("log_list.log")
For index = 1 To mylist.Count - 1
sw.WriteLine(mylist(index).comments)
Next
sw.Close()
Me.Invoke(Sub()
Label1.Text = "Log sucessfully saved"
End Sub)
End Sub