Proper disposal of COM interop objects in C# particularly MS Office applications

Question

I am developing an application that relies heavily on multiple Microsoft Office products including Access, Excel, Word, PowerPoint and Outlook among others. While doing rese

Answer 1

Objects should be disposed automatically by the GC after the object goes out of scope. If you need to release them sooner, you can use Marshal.ReleaseComObject http://msdn.microsoft.com/en-us/library/system.runtime.interopservices.marshal.releasecomobject.aspx

Answer 2

If you want to release COM objects fully especially in MS Office COM Objects, its very highly recommended that you release sub objects that you must have used which are inside the parent objects.

In your example, I would say release all Cell, Range any other objects that you may have used before releasing the worksheet that the cell, range or any other object belongs to.

Answer 3

Depending on the version of Office you are controlling through interop, and the circumstances that occur on the server, yes, you may need to do some serious convolutions to get rid of a running instance of one of the Office applications. There are unpredictable (and unnecessary) dialogs which, for example, Word will open when it is not interactive (None of the Office applications are particularly well designed for unattended execution, thus the recommendation that even with the latest versions that they not be installed for server-side use).

For server cases, consider using Aspose's stack rather than Office, or another of the alternatives. The interactive, local use cases, you may need that "extra vigorous killing" on occasion since the Office automation servers are particularly badly behaved unmanaged objects.