To what degree should I use Marshal.ReleaseComObject with Excel Interop objects?
- by DanM
I've seen several examples where Marshal.ReleaseComObject() is used with Excel Interop objects (i.e., objects from namespace Microsoft.Office.Interop.Excel), but I've seen it used to various degrees.
I'm wondering if I can get away with something like this:
var application = new ApplicationClass();
try
{
// do work with application, workbooks, worksheets, cells, etc.
}
finally
{
Marashal.ReleaseComObject(application)
}
Or if I need to release every single object created, as in this method:
public void CreateExcelWorkbookWithSingleSheet()
{
var application = new ApplicationClass();
var workbook = application.Workbooks.Add(_missing);
var worksheets = workbook.Worksheets;
for (var worksheetIndex = 1; worksheetIndex < worksheets.Count; worksheetIndex++)
{
var worksheet = (WorksheetClass)worksheets[worksheetIndex];
worksheet.Delete();
Marshal.ReleaseComObject(worksheet);
}
workbook.SaveAs(
WorkbookPath, _missing, _missing, _missing, _missing, _missing,
XlSaveAsAccessMode.xlExclusive, _missing, _missing, _missing, _missing, _missing);
workbook.Close(true, _missing, _missing);
application.Quit();
Marshal.ReleaseComObject(worksheets);
Marshal.ReleaseComObject(workbook);
Marshal.ReleaseComObject(application);
}
What prompted me to ask this question is that, being the LINQ devotee I am, I really want to do something like this:
var worksheetNames = worksheets.Cast<Worksheet>().Select(ws => ws.Name);
...but I'm concerned I'll end up with memory leaks or ghost processes if I don't release each worksheet (ws) object.
Any insight on this would be appreciated.
