C# Closing Microsoft Interop Excel Process after running

Question

I am uploading an excel file, opening it, reading the contents, closing it and removing it.

All works well, however I have noticed the process 'Microsoft Excel' still runs in the background in task manager.

I have tried searching around and have tried different answers but none of them work for me. Does anyone have any ideas?

I am trying different ways of closing the app, releasing the com but having no luck.

The code I am using:

    public ActionResult UploadUpdateOOBList()
    {
        CheckPermissions("UpdateOOBList");

        string[] typesallowed = new string[] { ".xls", ".xlsx" };

        HttpPostedFileBase file = Request.Files[0];
        var fname = file.FileName;

        if (!typesallowed.Any(fname.Contains))
        {
            return Json("NotAllowed");
        }

        file.SaveAs(Server.MapPath("~/Uploads/OOB List/") + fname);

        //Create COM Objects. Create a COM object for everything that is referenced
        Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();
        Microsoft.Office.Interop.Excel.Workbooks xlWorkbooks = xlApp.Workbooks;
        Microsoft.Office.Interop.Excel.Workbook xlWorkbook = xlWorkbooks.Open(Server.MapPath("~/Uploads/OOB List/") + fname);
        Microsoft.Office.Interop.Excel._Worksheet xlWorksheet = xlWorkbook.Sheets[2];
        Microsoft.Office.Interop.Excel.Range xlRange = xlWorksheet.UsedRange;

        //Create empty OOB data list
        List<OOBList.OOBDetails> oob_data = new List<OOBList.OOBDetails>();

        int rowcount = xlRange.Rows.Count;

        for (int down = 4; down <= rowcount; down++)
        {

            //Make sure first column isn't null
            if( xlRange.Cells[down, 1] != null && xlRange.Cells[down, 1].Value2 != null )
            {
                string siteno = xlRange.Cells[down, 1].Value2.ToString();
                string sitename = xlRange.Cells[down, 2].Value2.ToString();
                string description = xlRange.Cells[down, 4].Value2.ToString();
                string cabinoob = xlRange.Cells[down, 5].Value2.ToString();
                string toweroob = xlRange.Cells[down, 6].Value2.ToString();
                string manageoob = xlRange.Cells[down, 7].Value2.ToString();
                string resolutiondate = xlRange.Cells[down, 8].Value2.ToString();
                var resolutiondate_converted = DateTime.FromOADate(Convert.ToDouble(resolutiondate)).ToString("dd/MM/yyyy");

                oob_data.Add(new OOBList.OOBDetails
                {
                    SiteNo = siteno,
                    SiteName = sitename,
                    Description = description,
                    CabinOOB = cabinoob,
                    TowerOOB = toweroob,
                    ManageOOB = manageoob,
                    TargetResolutionDate = resolutiondate_converted
                });

                Debug.Write("Adding SiteNo: " + siteno);
            }

        }

        //HERE IS THE PROBLEM, DOESNT SEEM TO CLOSE THE PROCESS.
        xlWorkbook.Close();
        xlApp.Quit();

        System.Runtime.InteropServices.Marshal.ReleaseComObject(xlWorkbook);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(xlWorkbooks);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(xlWorksheet);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(xlRange);
        System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApp);
        xlWorkbook = null;
        xlWorkbooks = null;
        xlWorksheet = null;
        xlRange = null;
        xlApp = null;

        GC.Collect();

        //Now delete file.
        System.IO.File.Delete(Server.MapPath("~/Uploads/OOB List/") + fname);

        var nowdate = DateTime.Now.ToString("dd/MM/yyyy");
        System.IO.File.WriteAllText(Server.MapPath("~/Uploads/OOB List/lastupdated.txt"),nowdate);

        return Json("Success");

    }

Answer 1

found that somewhere: "Automation servers register themselves in the Running Object Table (ROT) through the RegisterActiveObject() API.

NOTE: If there are multiple instances of an automation server running at the same time, the GetActiveObject() API function returns the IDispatch pointer to the instance that was first running.

Theoretically, you can iterate the ROT for each individual instance, but Office applications do not register themselves if another instance is already in the ROT because the moniker for itself is always the same, and cannot be distinguished. This means that you cannot attach to any instance except for the first. However, because Office applications also register their documents in the ROT, you can successfully attach to other instances by iterating the ROT looking for a specific document, attaching to this document, and then getting the Application object from this document. For a code example of iterating the ROT and looking for a document name, click the article number below to view the article in the Microsoft Knowledge Base: 190985 How To Get IDispatch of an Excel or Word Document from an OCX"

hope this is a hint - whish I had known this back than....

Answer 2

The following code solved my problem upon nabuchodonossor's comment:

       //Create don't kill processes
        var dontkill = new List<Process>();
        Process[] procs = Process.GetProcessesByName("EXCEL");
        foreach (Process p in procs)
        {
            dontkill.Add(p);
        }

        //EXCEL CODE HERE.

        xlWorkbook.Close();
        xlApp.Quit();

        //Now kill only the created process above.
        procs = Process.GetProcessesByName("EXCEL");
        foreach (Process p in procs)
        {
            if( !dontkill.Contains(p))
            {
                p.Kill();
            }
        }
        Marshal.FinalReleaseComObject(xlApp);

Answer 3

When I worked with the Excel Interop library, I opened and closed the document with the following code:

Application xlApp = null;
Workbook xlWorkbook = null;
_Worksheet xlWorksheet = null;
Range xlRange = null;

try
{
    xlApp = new Application();
    xlWorkbook = xlApp.Workbooks.Open(filename);
    xlWorksheet = xlWorkbook.Sheets[1];
    xlRange = xlWorksheet.UsedRange;

    // Do stuff with excel data
}
finally
{
    GC.Collect();
    GC.WaitForPendingFinalizers();

    //release com objects to fully kill excel process from running in the background
    if (xlRange != null)
    {
        Marshal.ReleaseComObject(xlRange);
    }

    if (xlWorksheet != null)
    {
        Marshal.ReleaseComObject(xlWorksheet);
    }

    //close and release
    if (xlWorkbook != null)
    {
        xlWorkbook.Close();
        Marshal.ReleaseComObject(xlWorkbook);
    }

    //quit and release
    if (xlApp != null)
    {
        xlApp.Quit();
        Marshal.ReleaseComObject(xlApp);
    }
}

Answer 4

Just another note to you guys, I decided to use ClosedXML.

It took around 30 seconds for Interop Excel to read 750 rows.

Then it took ClosedXML 3 seconds to do the same thing with the following code which also does not leave any nasty processes behind:

//Create empty OOB data list
        List<OOBList.OOBDetails> oob_data = new List<OOBList.OOBDetails>();

        string fileName = Server.MapPath("~/Uploads/OOB List/") + fname;
        using (var excelWorkbook = new XLWorkbook(fileName))
        {
            var nonEmptyDataRows = excelWorkbook.Worksheet(2).RowsUsed();

            foreach (var dataRow in nonEmptyDataRows)
            {
                //for row number check
                if (dataRow.RowNumber() >= 4 )
                {

                    string siteno = dataRow.Cell(1).GetValue<string>();
                    string sitename = dataRow.Cell(2).GetValue<string>();
                    string description = dataRow.Cell(4).GetValue<string>();
                    string cabinoob = dataRow.Cell(5).GetValue<string>();
                    string toweroob = dataRow.Cell(6).GetValue<string>();
                    string manageoob = dataRow.Cell(7).GetValue<string>();
                    string resolutiondate = dataRow.Cell(8).GetValue<string>();
                    string resolutiondate_converted = resolutiondate.Substring(resolutiondate.Length - 9);

                    oob_data.Add(new OOBList.OOBDetails
                    {
                        SiteNo = siteno,
                        SiteName = sitename,
                        Description = description,
                        CabinOOB = cabinoob,
                        TowerOOB = toweroob,
                        ManageOOB = manageoob,
                        TargetResolutionDate = resolutiondate_converted
                    });

                    Debug.Write("Adding SiteNo: " + siteno + "\n");
                }
            }
        }