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(BooleanflushStream, 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\XXXXXXX\UserControls\ExportToExcel.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.RaisePostBackEvent(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\TemporaryASP.NET
Files\XXXX\cdf32a52\d1a5eabd\App_Web_enxdwlks.1.cs:line 0 at
System.Web.HttpApplication.CallHandlerExecutionStep.System.Web.HttpApplication.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?
If formatting is not an issue, I would say yes to CSV.
Another thing I noticed, you are using ExcelPackage. I ran into some issue using it with large files. I think It was the way it handled xml and exporting large files was really slow. I would recommend using some other library.