"The process cannot access the file ..." occurs when export crystal report

Question

We are using a web application developed in VS 2005, .NET 2.0 with the bundled Crystal Reports version 10.2.3600.0 running on a Windows 2003 Standard server with 4GB Ram and Dual CPU's. Periodically we are still receiving the following error in our production environment:
InnerException:
The process cannot access the file because it is being used by another process.
   at CrystalDecisions.ReportAppServer.Controllers.ReportSourceClass.Export(ExportOptions pExportOptions, RequestContext pRequestContext)
   at CrystalDecisions.ReportSource.EromReportSourceBase.ExportToStream(ExportRequestContext reqContext)
   at CrystalDecisions.CrystalReports.Engine.FormatEngine.ExportToStream(ExportRequestContext reqContext)
   at CrystalDecisions.CrystalReports.Engine.ReportDocument.ExportToStream(ExportOptions options)
   at CrystalDecisions.CrystalReports.Engine.ReportDocument.ExportToStream(ExportFormatType formatType)
This is occuring at the point on the code where the report is being exported to a PDF. Exporting the report to Excel does not appear to cause the error.
                Stream outStream = report.ExportToStream(ExportFormatType.PortableDocFormat);
                byte[] charStream = new byte[outStream.Length];
                outStream.Read(charStream, 0, (int)outStream.Length);
                if ((charStream != null) && (charStream.Length > 0))
                    HttpContext.Current.Response.ContentType = "application/pdf";
                    HttpContext.Current.Response.OutputStream.Write(charStream, 0, charStream.Length);
                    HttpContext.Current.Response.End();
            report.Close();
            report.Dispose();
            ds.Dispose();
            GC.Collect();
Closing and disposing of the report and dataset (xsd) are followed by a call for garbage collection. We are unable to produce the error in our development environmennt and have not at this point been unable to pinpoint a problematic report. The development team members do have SP1 installed. The report limit has not been changed from the standard of 75 jobs.  Reviewed the following document, Re: "The process cannot access the file ..." occurs when export crystal report However this applies to VS 2008. Any suggestions to resolve the issue would be greatly appreciated.
Thanks,
Joe

Answer 1

Good morning Joe
For more details re. loading please see the following resources:
[Crystal Reports 2008 Component Engine Scalability|http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/7025839b-00d4-2b10-33b4-cf0aa9e08412?quicklink=index&overridelayout=true]
[How Can I Optimize Scalability?|http://msdn.microsoft.com/en-us/library/ms225519.aspx]
[Choosing the Right Business Objects SDK for Your Needs|http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/40bccdfd-88a6-2b10-1da1-c47a54b625a7]
To answer your questions:
Is it correct to presume that the physical number of CPU's is not factored into the CPL? So that a Server with 2 or more processors does not increase the 3 concurrent requests? Therefore 2 CPU's would not increase the CPL limit to 6 processes?
- Server with 2 or more processors does not increase the 3 concurrent requests.
What would be an alternate solution to this limit be, considering the report requests could increase significantly?
- Only way around this would be to web farm the solution
If only only 3 reports can be processed at the same time. If one or more of the reports currently processing is taking longer due to receiving large amounts of data, how does that affect the queue? And what is stored in the queue, data and/or the report? Is this something that could consume memory?
- The report can take as much time as it needs. The result is that one license will not be released until the report is done. There is no data stored, just a pointer to the report. However queued apps will chew up memory, some times to the point of the server becoming unresponsive
I have read in the documentation on this site, that the dataset sent to the engine is copied in memory during report construction. So if a large amount of data is requested for a report (as an example 10+ MB) Could enough users requesting reports drive the memory up because memory usage doubled due to the dataset?
- Absolutely. See [Crystal Reports Guide to ADO.NET|http://www.sdn.sap.com/irj/boc/index?rid=/library/uuid/401c4455-a31d-2b10-ae96-fa57af5aec20].
Understanding the the CR DLL's are loaded on the first report request, do they get released at some point time due to inactivity or garbage collection? How much memory usage could be consumed when they load and stay resident?
- No they do not. Not as long as the application is running.
Ludek