Many "excel" processes shown on the task manager - processes

Question

Even when my app closes and finishes, when I watch on my task manager -> processes, there are many excel processes which even prevent my computer from shutting down.

Here is my code:

 private void write_data_to_excel(byte[] input)
 {
    FileStream f = File.OpenWrite("StocksData.xls");
    f.Write(input, 0, input.Length);
    f.Close();
 }

Another possible method who causes this:

private void get_stocks_data()
{
   byte[] result;
   byte[] buffer = new byte[4096];
   try
   {
      WebRequest wr = WebRequest.Create("http://www.tase.co.il/TASE/Pages/ExcelExport.aspx?sn=none&enumTblType=allShares&Columns=noneColumns&Titles=noneTitles&action=1&SubAction=0&GridId=33&CurGuid={0BDA5110-EF93-44CB-A0F0-468C6F502B51}&ExportType=1");
      using (WebResponse response = wr.GetResponse())
      {
         using (Stream responseStream = response.GetResponseStream())
         {
            using (MemoryStream memoryStream = new MemoryStream())
            {
               int count = 0;
               do
               {
                  count = responseStream.Read(buffer, 0, buffer.Length);
                  memoryStream.Write(buffer, 0, count);
               } while (count != 0);
               result = memoryStream.ToArray();
               write_data_to_excel(result);
            }
         }
      }
   }

My code also contains:

xlApp = new Excel.Application();
xlWorkBook = xlApp.Workbooks.Open(file, 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

These methods are called priodicly... What am I not closing or...?

score 2 · Answer 1 · answered Apr 26 '11 at 17:39

You need a try/catch around the code that opens the Excel application and any workbooks, and a finally block that closes open workbooks and quits the application:

    finally
    {
        if (wb != null) wb.Close();
        if (app != null) app.Quit();

        app = null;
    }

Note that if you're debugging your code and stop the debugger in the middle, you'll still have the Excel process because your finally block will not execute.

score 2 · Answer 2 · answered Apr 26 '11 at 17:44

2

The most solid way I've found to do this is to release each worksheet within the workbook using:

System.Runtime.InteropServices.Marshal.ReleaseComObject(worksheet);

and then release the Excel app using the same call:

System.Runtime.InteropServices.Marshal.ReleaseComObject(excelApp);

then to do:

System.GC.Collect();
System.GC.WaitForPendingFinalizers();

answered Apr 26 '11 at 17:44

mservidio

12,817
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Those last two are not needed when you set your .NET references to null – Emond Apr 26 '11 at 18:14

score 2 · Accepted Answer · edited May 23 '17 at 12:10

2

Take a look at How to properly clean up Excel Interop objects in C#. You need to be very careful about cleaning up all the COM objects when using the Excel Interop. The accepted answer in the post will explain why what you are doing is causing the process to stay open. The main point is to Never use 2 dots with com objects.

edited May 23 '17 at 12:10

Community

1
1

answered Apr 26 '11 at 18:02

SwDevMan81

48,814
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score 1 · Answer 4 · answered Apr 26 '11 at 17:42

1

Sometimes, when the COM applications leak, a call to Marshal.ReleaseComObject() solves the problem

answered Apr 26 '11 at 17:42

Emond

50,210
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Many "excel" processes shown on the task manager - processes

4 Answers4