Re: Out-of-memory error: sample app

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See responses inline:

The other problem I've seen is that after the 2.0 thread dies or is
killed if I return to that page - without clicking the button to
request datarows - memory begins to skyrocket again immediately. It
seems like ASP.NET is somehow remembering what it was doing when it
died and wants to pick up and do it again - which of course leads to
another crash.

Sounds like it's taking the ViewState of the textbox and re-submitting
which is of course, going to ask for the same data again, and thus,
crash your app again.

Does this happen when you CLOSE the web browser and re-open?

Note: I know it's poor practice to load so much data into a grid.

Yes, Indeed it is. There is no way you can limit the amount of data to
be populated?

How much data are we actually talking about here? 50 rows? 500 rows?
5000 rows? 500,000 rows?


I'm
dealing with a huge production legacy application here and we are in
the process of refactoring. In order to take advantage of some third
party tools we upgraded to framework 2.0. At this point we started
having memory problems with some admittedly poorly designed pages that
allow users to pull ridiculous amounts of data. So if your only answer
is "don't pull so much data" well . . . thanks, no kidding.

Don't pull so much data. =)

Here's my sample app - basically it creates a huge datatable and tries
to load it into a grid:

BigTable.aspx:

<%@ Page language="c#" Codebehind="BigTable.aspx.cs"
AutoEventWireup="false" Inherits="BigTable.BigTable" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
<title>BigTable</title>
<meta name="GENERATOR" Content="Microsoft Visual Studio .NET 7.1">
<meta name="CODE_LANGUAGE" Content="C#">
<meta name="vs_defaultClientScript" content="JavaScript">
<meta name="vs_targetSchema"
content="http://schemas.microsoft.com/intellisense/ie5";>
</HEAD>
<body MS_POSITIONING="GridLayout">
<form id="Form1" method="post" runat="server">
<asp:DataGrid id="grdRows" style="Z-INDEX: 101; LEFT: 1px; POSITION:
absolute; TOP: 1px" runat="server"
Width="792px"></asp:DataGrid>
&nbsp;
<asp:Label id="lblRowsToLoad" style="Z-INDEX: 104; LEFT: 8px;
POSITION: absolute; TOP: 152px"
runat="server" Width="144px">Rows To Load</asp:Label>
<asp:TextBox id="txtRowsToLoad" style="Z-INDEX: 103; LEFT: 8px;
POSITION: absolute; TOP: 176px"
runat="server" Width="80px">5</asp:TextBox>
<asp:Button id="btnLoadRows" style="Z-INDEX: 102; LEFT: 8px;
POSITION: absolute; TOP: 200px"
runat="server" Text="Load Rows"
OnClick="btnLoadRows_Click"></asp:Button>
&nbsp;
</form>
</body>
</HTML>




BigTable.aspx.cs:


using System;
using System.Data;

namespace BigTable
{
public partial class BigTable : System.Web.UI.Page
{
protected System.Web.UI.WebControls.DataGrid grdRows;
protected System.Web.UI.WebControls.Button btnLoadRows;
protected System.Web.UI.WebControls.TextBox txtRowsToLoad;
protected System.Web.UI.WebControls.Label lblRowsToLoad;

protected void btnLoadRows_Click(object sender,
System.EventArgs e)
{
System.Data.DataTable dt = new DataTable();
for (int x = 0; x < 10; x++) //10 columns
{
dt.Columns.Add(x.ToString(), typeof(String));
}
System.Data.DataRow dr;
int yTotal = int.Parse(txtRowsToLoad.Text);
for (int y = 0; y < yTotal; y++) //Add the requested number
of rows.
{
dr = dt.NewRow();
for (int x = 0; x < 10; x++) //insert a string value
into each column of each row.
{
dr[x] = x.ToString();
}
dt.Rows.Add(dr);
}
grdRows.DataSource = dt;
grdRows.DataBind();
}
}
}


Can we see any "actual" code? This seems to just be an example of
building a DataTable.

BTW, your Web frontend really "shouldn't" be creating your data model
on the fly. Simply from a maintainability stand-point. I always defer
these tasks to another tier/assembly. Too much messiness in the UI =)

Hope this might help!

Sean

.

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