Summary: ASP.Net website with a couple hundred users. Data is exported to Excel files which can be relatively large (~5 MB).

In the pilot phase (just a few users), we are already seeing occasional errors on the server in the exporting method.

Here's the stack trace:

System.Web.HttpUnhandledException: Exception of type 'System.Web.HttpUnhandledException' was thrown. ---> System.OutOfMemoryException: Exception of type 'System.OutOfMemoryException' was thrown. at System.IO.MemoryStream.set_Capacity(Int32 value) at System.IO.MemoryStream.EnsureCapacity(Int32 value) at System.IO.MemoryStream.Write(Byte[] buffer, Int32 offset, Int32 count)
at MS.Internal.IO.Packaging.TrackingMemoryStream.Write(Byte[] buffer, Int32 offset, Int32 count)
at MS.Internal.IO.Packaging.SparseMemoryStream.WriteAndCollapseBlocks(Byte[ ] buffer, Int32 offset, Int32 count)
at MS.Internal.IO.Packaging.SparseMemoryStream.Write(Byte[] buffer, Int32 offset, Int32 count)
at MS.Internal.IO.Packaging.CompressEmulationStream.Write(Byte[] buffer, Int32 offset, Int32 count)
at MS.Internal.IO.Packaging.CompressStream.Write(Byte[] buffer, Int32 offset, Int32 count)
at MS.Internal.IO.Zip.ProgressiveCrcCalculatingStream.Write(Byte[] buffer, Int32 offset, Int32 count)
at MS.Internal.IO.Zip.ZipIOModeEnforcingStream.Write(Byte[] buffer, Int32 offset, Int32 count)
at System.IO.StreamWriter.Flush(Boolean flushStream, Boolean flushEncoder)
at System.IO.StreamWriter.Write(String value) at System.Xml.XmlTextEncoder.Write(String text) at System.Xml.XmlTextWriter.WriteString(String text) at System.Xml.XmlText.WriteTo(XmlWriter w) at System.Xml.XmlAttribute.WriteContentTo(XmlWriter w) at System.Xml.XmlAttribute.WriteTo(XmlWriter w) at System.Xml.XmlElement.WriteTo(XmlWriter w) at System.Xml.XmlElement.WriteContentTo(XmlWriter w) at System.Xml.XmlElement.WriteTo(XmlWriter w) at System.Xml.XmlElement.WriteContentTo(XmlWriter w) at System.Xml.XmlElement.WriteTo(XmlWriter w) at System.Xml.XmlElement.WriteContentTo(XmlWriter w) at System.Xml.XmlElement.WriteTo(XmlWriter w) at System.Xml.XmlDocument.WriteContentTo(XmlWriter xw) at System.Xml.XmlDocument.WriteTo(XmlWriter w) at System.Xml.XmlDocument.Save(Stream outStream) at OfficeOpenXml.ExcelWorksheet.Save() in C:\temp\XXXXXXXXXX\ExcelPackage\ExcelWorksheet.cs:line 605 at OfficeOpenXml.ExcelWorkbook.Save() in C:\temp\XXXXXXXXXX\ExcelPackage\ExcelWorkbook.cs:line 439 at OfficeOpenXml.ExcelPackage.Save() in C:\temp\XXXXXXXXXX\ExcelPackage\ExcelPackage.cs:line 348 at Framework.Exporting.Business.ExcelExport.BuildReport(HttpContext context) at WebUserControl.BtnXLS_Click(Object sender, EventArgs e) in C:\TEMP\XXXXXXXXXX\XXXXXXXXXX\OneList\UserControls\TicketReportExporter. ascx.cs:line 108 at System.Web.UI.WebControls.Button.OnClick(EventArgs e) at System.Web.UI.WebControls.Button.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.Button.System.Web.UI.IPostBackEventHandler.Rai sePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument)
at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace --- at System.Web.UI.Page.HandleError(Exception e) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) at System.Web.UI.Page.ProcessRequest()
at System.Web.UI.Page.ProcessRequestWithNoAssert(HttpContext context) at System.Web.UI.Page.ProcessRequest(HttpContext context) at ASP.XXXXXXXXXXX_aspx.ProcessRequest(HttpContext context) in c:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files\XXXX\cdf32a52\d1a5eabd\App_Web_enxdwlks.1.cs:line 0 at System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpAppli cation.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Even aside from this particular problem, in general exporting to Excel requires the instantiation of huge Excel objects on the server for each request, which I've always assumed to mean disqualifies Excel for "serious" work on a highly-loaded server. Is there any general way to export to Excel in a "light-weight" manner? Would simply streaming the data into a CSV file work for this?