Question

总结：ASP.Net网站上有几百个用户。数据导出到Excel文件，这些文件可能相对较大（约5 MB）。

在试用阶段（只有少数用户），我们已经在导出方法中看到服务器上偶尔会出现错误。

这是堆栈跟踪：

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)

即使不考虑这个特殊问题，通常导出到Excel需要在服务器上为每个请求实例化大量Excel对象，我一直认为这意味着取消Excel在高负载服务器上“严肃”工作的资格。是否有任何通用的方式以“轻量级”方式导出到Excel？将数据流式传输到CSV文件只是为此工作吗？

Answer 1

我会把它卸载到另一台机器上。创建一个Windows服务，该服务接受命令，生成文件，将其压缩，将其保存到磁盘，然后返回文件的路径，以便Web应用程序可以为其提供服务。这是您不想让网络服务器陷入困境的真正占用大量内存的操作之一。

Answer 2

如果格式不是问题，我会对CSV说“是”。

我注意到的另一件事是，您正在使用ExcelPackage。我在使用大文件时遇到了一些问题。我认为这是处理xml的方式，导出大文件的速度非常慢。我建议使用其他一些库。

Answer 3

我知道这篇文章真的很老但是如果你使用的是ExcelPackage，我在“LoadFromDataTable”调用中不断得到内存不足的异常，这个数据包有大约300k行。我找到了我的意思是大约100k，偶尔会发生错误。

我在大约50k时使用了一个split datatable方法，并遍历了datatable集合，然后调用了“LoadFromDataTable”方法。似乎只是工作问题是方法删除前一个。如果我能弄清楚如何追加我会没事的。 Excel出口最好我告诉你。

导出到Excel功能是否可以扩展？

3 个答案: