Close Excel instance when Windows Form is closed by user in a VB 2008 application

I'm currently developing an application using Visual Basic, in Visual Studio 2008 Professional, on a Windows XP machine. However, we have both XP and Windows 7 client workstations in our office.

In my application, I'm exporting the results displayed in a DataGridView control to MS Excel, using the methods in the Microsoft.Office.Interop.Excel namespace. The procedure which opens the instance of Excel and exports the data is running in a separate thread from the form which contains the DataGridView control. This is working well.

However, if the user closes the form before the export is completed I want to cancel the thread and close the instance of Excel without saving it. I can use the Thread.Abort method in my form's FormClosing event handler to kill the thread, but the Excel process is still hanging out there even after the application is closed.

What would be the best way to identify and kill that Excel process if the user closes the form prior to the export being completed?
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JeffEdmundsAsked:
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CodeCruiserCommented:
I don't think there is any event on the thread which would indicate thread being aborted.

One option is to declare the Excel app variable in common place such as module. Thread then populates it. When calling thread.abort, you can dispose that app variable after aborting thread.
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JeffEdmundsAuthor Commented:
You nailed it... I had the declaration inside the module that was being called by the separate thread. Declaring within the form's Declarations section gave it the necessary scope.

Private xlApp As Excel.Application
Private myThread As Thread
....

Then in the FormClosing event handler:

If Not myThread.Equals(Nothing) Then
    If myThread.IsAlive Then
        myThread.Abort()
        xlApp.Quit()
    End If
End If

Seems to be working well - thanks!
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