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POHow to clean up COM references in .NET when app will be left running?
 

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  1. POHow to clean up COM references in .NET when app will be left running?
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    <p>I am working on a .NET program that starts a new instance of Excel, does some work, then ends, but must leave Excel running. Later, when the program runs again, it will attempt to hook into the previous instance.</p> <p>What is the best way to handle the releasing of COM objects in this situation? If I do not do a "ReleaseComObject" on the app object the first time, then on the second run get the active object, then finally release the com object, do I have a memory leak?</p> <p>The following simplified code illustrates what I am trying to do:</p> <pre><code>private Microsoft.Office.Interop.Excel.Application xlsApp; private Microsoft.Office.Interop.Excel.Workbook xlsWb; public void RunMeFirst() { //Start a new instance System.Type oSEType = Type.GetTypeFromProgID("Excel.Application"); xlsApp = Activator.CreateInstance(oSEType); xlsWb = xlsApp.Workbooks.Open("C:\\test1.xls"); //Do some stuff xlsWb.Close(false); Cleanup(ref xlsWb); //Do not quit Excel here //No Cleanup of xlsApp here? Is this OK? System.Environment.Exit(0); } public void RunMeSecond() { //Hook into existing instance xlsApp = Marshal.GetActiveObject("Excel.Application"); xlsWb = xlsApp.Workbooks.Open("C:\\test2.xls"); //Do some stuff xlsWb.Close(false); Cleanup(ref xlsWb); xlsApp.Quit(); Cleanup(ref xlsApp); System.Environment.Exit(0); } public void Cleanup(ref object theObj) { GC.Collect(); GC.WaitForPendingFinalizers(); GC.Collect(); GC.WaitForPendingFinalizers(); Marshal.FinalReleaseComObject(theObj); theObj = null; } </code></pre> <p>Thanks</p>
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    1. COshouldn't your GC calls be _after_ you release the COM object?
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    2. COWhy should there be any GC calls at all?
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    3. COThis guy seems to make a good case for putting it first: http://www.xtremevbtalk.com/showthread.php?t=160433. I've seen it the other way too, and, others say it is not necessary at all. I am open to all comments and suggestions.
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      1. USBama91
 

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