Unable to kill excel processes - vb.net

Question

I am using the followiwing code to do some copying and pasting with excel files:
Imports Excel = Microsoft.Office.Interop.Excel
Imports System.IO
Imports System.Runtime.InteropServices
Private Sub btnCombine_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCombine.Click
Dim xlAppSource As New Excel.Application
Dim xlAppTarget As New Excel.Application
Dim xlWbSource As Excel.Workbook
Dim xlWbTarget As Excel.Workbook
Dim xlsheetSource As Excel.Worksheet
Dim xlsheetTarget As Excel.Worksheet
Dim xlRangeSource As Excel.Range
Dim xlRangeTarget As Excel.Range
Dim Progress As Integer = 0
pbrProgress.Minimum = 0
pbrProgress.Maximum = amountOfFiles
btnCombine.Enabled = False
btnSelect.Enabled = False
pbrProgress.Visible = True
getSaveLocation()
MakeExcelFile()
'loop through all excel files to get the required data
For i = 0 To amountOfFiles - 1
Dim CurrentFile As String = strFileNames(i)
Dim IntAmountOfRows As Integer = amountOfRows(CurrentFile)
Dim intStartOfEmptyRow As Integer = amountOfRows(SummaryLocation)
xlAppSource.DisplayAlerts = False
xlAppTarget.DisplayAlerts = False
'Set current workbook
xlWbSource = xlAppSource.Workbooks.Open(CurrentFile)
xlWbTarget = xlAppTarget.Workbooks.Open(SummaryLocation)
'set current worksheet
xlsheetSource = xlWbSource.ActiveSheet
xlsheetTarget = xlWbTarget.ActiveSheet
'copy range of data from source to target file
xlRangeSource = xlsheetSource.Range("A2:k" & IntAmountOfRows)
xlRangeSource.Copy()
xlRangeTarget = xlsheetTarget.Range("A" & intStartOfEmptyRow)
xlRangeTarget.PasteSpecial(Excel.XlPasteType.xlPasteValues)
'save summary file before closing
xlsheetTarget.SaveAs(SummaryLocation)
'updating progress bar
Progress = Progress + 1
pbrProgress.Value = Progress
Next
'close excel
xlWbSource.Close(True)
xlWbTarget.Close(True)
xlAppSource.Quit()
xlAppTarget.Quit()
xlAppSource.DisplayAlerts = True
xlAppTarget.DisplayAlerts = True
'Cleanup
Marshal.ReleaseComObject(xlAppSource)
Marshal.ReleaseComObject(xlAppTarget)
Marshal.ReleaseComObject(xlWbSource)
Marshal.ReleaseComObject(xlWbTarget)
Marshal.ReleaseComObject(xlsheetSource)
Marshal.ReleaseComObject(xlsheettarget)
Marshal.ReleaseComObject(xlRangeSource)
Marshal.ReleaseComObject(xlRangeTarget)
xlAppSource = Nothing
xlAppTarget = Nothing
xlWbSource = Nothing
xlWbTarget = Nothing
xlsheetSource = Nothing
xlsheetTarget = Nothing
xlRangeSource = Nothing
xlRangeTarget = Nothing
MsgBox("Samenvoegen compleet")
init()
End Sub
I have tried every solution given on SO:
Never use 2 points on a line
I have tried using marshall.ReleaseComObject
I have tried setting the objects to "Nothing"
However, everytime I run the application, there will be 10-20 excel processes still running.

Answer 1

Option Explicit
Sub Main()
Dim xlApp As Excel.Application
Set xlApp = New Excel.Application
xlApp.Visible = False
xlApp.DisplayAlerts = False
Dim xlWb As Workbook
Set xlWb = xlApp.Workbooks.Open("C:\...\path")
Dim xlSht As Worksheet
Set xlSht = xlWb.Sheets(1)
xlSht.Range("A1") = "message from " & ThisWorkbook.FullName
xlWb.Saved = True
xlWb.Save
xlWb.Close
xlApp.Quit
End Sub
Works for me every single time and does not leave any Excel processes hanging in the task manager.
Note: if your code breaks at some point and you do not handle the already opened objects properly then they will just hang in the processes tab in the Task Manager. If you haven't implemented error handling in your code then start here.
just consider this as alternative
Option Explicit
Sub Main()
On Error GoTo ErrHandler
Dim xlApp As Excel.Application
Set xlApp = New Excel.Application
xlApp.Visible = False
xlApp.DisplayAlerts = False
Dim xlWb As Workbook
Set xlWb = xlApp.Workbooks.Open("C:\...\path")
Dim xlSht As Worksheet
Set xlSht = xlWb.Sheets(1)
xlSht.Range("A1") = "message from " & ThisWorkbook.FullName
xlWb.Saved = True
xlWb.Save
xlWb.Close
xlApp.Quit
Exit Sub
ErrHandler:
xlWb.Saved = True
xlWb.Save
xlWb.Close
xlApp.Quit
End Sub

Answer 2

The Interop Marshal release doesn't always work because Excel XP and lower suck at releasing. I had to use your loop, but replace the Process.Close() and Process.Quit() with Process.Kill(). Works like a charm. Just be careful that you want ALL versions of excel.exe to be killed, because they will.
I use this:
Workbook.Save()
Workbook.Close()
Application.Quit()
System.Runtime.InteropServices.Marshal.ReleaseComObject(Application)
Worksheet = Nothing
Workbook = Nothing
Application = Nothing
Dim proc As System.Diagnostics.Process
For Each proc In System.Diagnostics.Process.GetProcessesByName("EXCEL")
proc.Kill()
Next

Answer 3

When you do anything with the Excel Interop, it creates a new process.
The problem with killing all Excel processes is that you may kill a process that you are working with. You can kill all processes which have been running for a certain length of time (i.e. from a certain timestamp) with:
Dim proc As System.Diagnostics.Process
Dim info As ManagementObject
Dim search As New ManagementObjectSearcher("SELECT ProcessId FROM Win32_process WHERE caption = 'Excel'")
For Each info In search.Get()
'The string will give you the time that the process started
'You can then subtract that from the current time to see if you want to kill the process
Dim TheString As String = info.GetText(TextFormat.Mof).ToString
'Kill the process according to its ID
proc = System.Diagnostics.Process.GetProcessById(Mid$(TheString, _
(Len(TheString) - 8), 4))
proc.CloseMainWindow()
proc.Refresh()
If proc.HasExited Then GoTo NoKill
proc.Kill()
NoKill:
Next
You'll need to add:
Imports System.Management
and add the reference for the 'System.Management' to your project.

Answer 4

You can obtain the process ID from the Excel.Application hwnd and use that to kill the process safely.