Rendering ReportViewer on another thread

Question

I'm trying to render ReportViewer on another thread in ASP .Net:

    public ActionResult GenerateReport()
    {
    var task = Task.Factory.StartNew(() =>
    {
        try
        {
            using (LocalReport localReport = new LocalReport())
            {
                System.Reflection.Assembly assembly = System.Reflection.Assembly.LoadFrom(AppDomain.CurrentDomain.BaseDirectory + "bin\\" + "Reports.dll");
                using (System.IO.Stream stream = assembly.GetManifestResourceStream("Report.rdlc"))
                {


                    localReport.LoadReportDefinition(stream);
                    string mimeType;
                    string encoding;
                    string fileNameExtension;

                    Warning[] warnings;
                    string[] streams;
                    byte[] rendered;

                    //Render the report
                    renderedBytes = localReport.Render(
                        "PDF",
                        deviceInfo,
                        out mimeType,
                        out encoding,
                        out fileNameExtension,
                        out streams,
                        out warnings);

                   Session["Report"] = renderedBytes;
                }
            }
        }
        catch (Exception ex)
        {
            Logger.Error("Error", ex);
        }
    });

    return new View();
 }

But I'm geeting this exception:

Microsoft.Reporting.WebForms.LocalProcessingException: An error occurred during local report processing. ---> Microsoft.ReportingServices.ReportProcessing.ReportProcessingException: Failed to load expression host assembly. Details: Invalid token for impersonation - it cannot be duplicated.
   at Microsoft.ReportingServices.RdlExpressions.ReportRuntime.ProcessLoadingExprHostException(ObjectType assemblyHolderObjectType, Exception e, ProcessingErrorCode errorCode)
   at Microsoft.ReportingServices.RdlExpressions.ReportRuntime.LoadCompiledCode(IExpressionHostAssemblyHolder expressionHostAssemblyHolder, Boolean includeParameters, Boolean parametersOnly, ObjectModelImpl reportObjectModel, ReportRuntimeSetup runtimeSetup)
   at Microsoft.ReportingServices.OnDemandProcessing.Merge.Init(Boolean includeParameters, Boolean parametersOnly)
   at Microsoft.ReportingServices.OnDemandProcessing.Merge.Init(ParameterInfoCollection parameters)
   at Microsoft.ReportingServices.ReportProcessing.Execution.ProcessReportOdp.CreateReportInstance(OnDemandProcessingContext odpContext, OnDemandMetadata odpMetadata, ReportSnapshot reportSnapshot, Merge& odpMerge)
   at Microsoft.ReportingServices.ReportProcessing.Execution.ProcessReportOdp.Execute(OnDemandProcessingContext& odpContext)
   at Microsoft.ReportingServices.ReportProcessing.Execution.RenderReportOdpInitial.ProcessReport(ProcessingErrorContext errorContext, ExecutionLogContext executionLogContext, UserProfileState& userProfileState)
   at Microsoft.ReportingServices.ReportProcessing.Execution.RenderReport.Execute(IRenderingExtension newRenderer)
   at Microsoft.ReportingServices.ReportProcessing.ReportProcessing.RenderReport(IRenderingExtension newRenderer, DateTime executionTimeStamp, ProcessingContext pc, RenderingContext rc, IChunkFactory yukonCompiledDefinition)
   at Microsoft.Reporting.LocalService.CreateSnapshotAndRender(ReportProcessing repProc, IRenderingExtension renderer, ProcessingContext pc, RenderingContext rc, SubreportCallbackHandler subreportHandler, ParameterInfoCollection parameters, DatasourceCredentialsCollection credentials)
   at Microsoft.Reporting.LocalService.Render(String format, String deviceInfo, String paginationMode, Boolean allowInternalRenderers, IEnumerable dataSources, CreateAndRegisterStream createStreamCallback)
   at Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, PageCountMode pageCountMode, CreateAndRegisterStream createStreamCallback, Warning[]& warnings)
   --- End of inner exception stack trace ---
   at Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, PageCountMode pageCountMode, CreateAndRegisterStream createStreamCallback, Warning[]& warnings)
   at Microsoft.Reporting.WebForms.LocalReport.InternalRender(String format, Boolean allowInternalRenderers, String deviceInfo, PageCountMode pageCountMode, String& mimeType, String& encoding, String& fileNameExtension, String[]& streams, Warning[]& warnings)
   at Microsoft.Reporting.WebForms.LocalReport.Render(String format, String deviceInfo, PageCountMode pageCountMode, String& mimeType, String& encoding, String& fileNameExtension, String[]& streams, Warning[]& warnings)
   at Web.Controllers.ReportsController()

Thanks, and appreciate any help

First question (assuming this is still a problem): can you run it successfully on the same thread?) — Ann L.
Hi, on the same thread it runs succesfully. I decompile the dll and trace that this line is executed windowsImpersonationContext = WindowsIdentity.Impersonate(IntPtr.Zero);. Thanks — amit
Are you doing any kind of impersonation in your web.config? Are you referencing any additional assemblies in your report? — Ann L.
I'm not doing any kind of impersonation, but the identity of the AppPool is custom. In the report there arn't additional assemblies. It has expressions. — amit

Juan Pablo Gomez Juan Pablo Gomez · Accepted Answer · 2014-10-07T19:53:23

I was experiencig the same problem but with WPF App.

It seems that ReportViewer.RefreshReport Allready runs in another thread.

Just remove the async / Task and It Works fine even if you refresh some them at the same thread / time.

            foreach (ReportViewer r in ListaReportes)
            {
                ContentPresenter Presenter = new ContentPresenter();
                Presenter.Width = 200;
                Presenter.Height = 260;
                WindowsFormsHost Host = new WindowsFormsHost();
                Host.Child = r;
                Presenter.Content = Host;
                Miniaturas.Children.Add(Presenter);

                try
                {
                    r.RefreshReport();
                } catch(Exception)
                {
                }
            }

This code add many reports and all of them starts refreshing at the same time.

Rendering ReportViewer on another thread

1 Answers