在多线程C＃应用程序中使用互操作的Excel文件操作失败

Question

I've an application that automates some file related jobs. Every job is executed inside separate threads. One kind of job is exporting an Excel file to HTML format. I use Microsoft.Office.Interop.Excel namespace for this purpose. My application was working fine under Windows Server 2008 environment but we upgraded our server to Windows Server 2012 and I started to get the following error :

The message filter indicated that the application is busy. (Exception from HRESULT: 0x8001010A (RPC_E_SERVERCALL_RETRYLATER))

The thing is first call to export function successfully exports Excel file to HTML but successive calls fails with the above error. I make sure to close and finalize all my Excel related objects and check from task manager that excel.exe is not working but with no luck.

I use the following code to retry if this error occurs but it keeps getting the exception and fails after 5 retries

while (!success)
            {
try
                {
                    ExportExcel();
                    success = true;
                    System.Threading.Thread.Sleep(2000);
                }
                catch (System.Runtime.InteropServices.COMException loE)
                {
                    tryCount++;
                    if (loE.HResult.ToString("X") == "80010001" || loE.HResult.ToString("X") == "8001010A" && tryCount<5)
                    {                                                                     
                      System.Threading.Thread.Sleep(2000);
                    }
                    else
                    {
                        throw;
                    }
                }
             }

I suspect this might be something related some threading error but I can't come up with an answer. Any insight would be helpful.

Thank you Joe for pointing out the right way:

I ended up using a solution with a mixture of the following links: http://blogs.artinsoft.net/Mrojas/archive/2012/09/28/Office-Interop-and-Call-was-rejected-by-callee.aspx

http://blogs.msdn.com/b/pfxteam/archive/2010/04/07/9990421.aspx

So I used something like the following:

StaTaskScheduler cts=new StaTaskScheduler(1);
TaskFactory factory;          
factory = new TaskFactory(cts);
Task jobRunTask = factory.StartNew(() =>
{
   MessageFilter.Register();
   ExcelInteropFunction();
   MessageFilter.Revove();
 });

Answer 1

I believe the Excel object model is apartment threaded, so calls from your multiple threads will be marshaled to the same thread in the Excel process - which may be busy especially if there are several client threads.

You can implement IMessageFilter (OLE message filter, not to be confused with System.Windows.Forms.IMessageFilter ) to provide custom retry logic.

Your server upgrade might have changed the timing characteristics so that the problem occurs more frequently.

UPDATE

Here is a sample basic implementation of an OLE message filter:

    // Definition of the IMessageFilter interface which we need to implement and 
    // register with the CoRegisterMessageFilter API.
    [ComImport(), Guid("00000016-0000-0000-C000-000000000046"), InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
    interface IOleMessageFilter // Renamed to avoid confusion w/ System.Windows.Forms.IMessageFilter
    {
        [PreserveSig]
        int HandleInComingCall(int dwCallType, IntPtr hTaskCaller, int dwTickCount, IntPtr lpInterfaceInfo);
        [PreserveSig]
        int RetryRejectedCall(IntPtr hTaskCallee, int dwTickCount, int dwRejectType);
        [PreserveSig]
        int MessagePending(IntPtr hTaskCallee, int dwTickCount, int dwPendingType);
    }

    internal sealed class OleMessageFilter : IOleMessageFilter, IDisposable
    {
        [DllImport("ole32.dll")]
        private static extern int CoRegisterMessageFilter(IOleMessageFilter newFilter, out IOleMessageFilter oldFilter);

        private bool _isRegistered;
        private IOleMessageFilter _oldFilter;

        public OleMessageFilter()
        {
            Register();
        }

        private void Register()
        {
            // CoRegisterMessageFilter is only supported on an STA thread.  This will throw an exception
            // if we can't switch to STA
            Thread.CurrentThread.SetApartmentState(ApartmentState.STA);

            int result = CoRegisterMessageFilter(this, out _oldFilter);
            if (result != 0)
            {
                throw new COMException("CoRegisterMessageFilter failed", result);
            }
            _isRegistered = true;
        }

        private void Revoke()
        {
            if (_isRegistered)
            {
                IOleMessageFilter revokedFilter;
                CoRegisterMessageFilter(_oldFilter, out revokedFilter);
                _oldFilter = null;
                _isRegistered = false;
            }
        }

        #region IDisposable Members

        private void Dispose(bool disposing)
        {
            if (disposing)
            {
                // Dispose managed resources
            }
            // Dispose unmanaged resources
            Revoke();
        }

        void IDisposable.Dispose()
        {
            GC.SuppressFinalize(this);
            Dispose(true);
        }

        ~OleMessageFilter()
        {
            Dispose(false);
        }

        #endregion

        #region IOleMessageFilter Members

        int IOleMessageFilter.HandleInComingCall(int dwCallType, IntPtr hTaskCaller, int dwTickCount, IntPtr lpInterfaceInfo)
        {
            return 0; //SERVERCALL_ISHANDLED
        }

        int IOleMessageFilter.RetryRejectedCall(IntPtr hTaskCallee, int dwTickCount, int dwRejectType)
        {
            if (dwRejectType == 2) // SERVERCALL_RETRYLATER
            {
                return 200; // wait 200ms and try again
            }

            return -1; // cancel call
        }

        int IOleMessageFilter.MessagePending(IntPtr hTaskCallee, int dwTickCount, int dwPendingType)
        {
            return 2; //PENDINGMSG_WAITDEFPROCESS
        }
        #endregion
    }

You can also look at this sample , though it displays a prompt asking the user if they want to retry, which is probably not appropriate if your client is multithreaded and server-based.