I posted this to an ASP.Net group awhile ago, but nobody responded, so
maybe this more in the C# realm.  Anyway, I launch an asynchronous
thread by clicking ButtonInitAsyncThread, which works fine.  When it's
done, it sends back it's results.

But, while this thread is still running, if I click on
ButtonCheckThreadStatus, which has nothing to do with the async thread
running, it cancels the thread, and the thread never sends back the
results.  What causes this?

thanks  -James

The complete C# code-behind:

using System;
using System.Threading;

public partial class testThreads : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
    }

    public delegate long SampSyncSqrDelegate(long i);

    protected void ButtonInitAsyncThread_Click(object sender, EventArgs
e)  // async call
    {
        long inParm = Convert.ToInt32(TextBoxInParm.Text);
        long callResult = -1;

        WorkerClass sampSyncObj = new WorkerClass();

        // launch longWindedMethod method Asynchronously:
        SampSyncSqrDelegate sampleDelegate = new
SampSyncSqrDelegate(sampSyncObj.longWindedMethod);

        IAsyncResult aResult = sampleDelegate.BeginInvoke(inParm, null,
null);

        //Wait for the call to complete
        aResult.AsyncWaitHandle.WaitOne();

        // get the output returned back:
        callResult = sampleDelegate.EndInvoke(aResult);
        LabelThreadStatus.Text = Convert.ToString(callResult);
    }

    protected void ButtonCheckThreadStatus_Click(object sender,
EventArgs e)
    {
        Label1.Text = Convert.ToString(DateTime.Now);
    }
}

public class WorkerClass
{
    // A method that does some time-consuming work - returns the number
passed in + 'a':
    public long longWindedMethod(long longIn)
    {
        int a = 0;

        while (a < 5)
        {
            System.Threading.Thread.Sleep(1000);
            System.Console.WriteLine(a);
            a++;
        }
        return a + longIn;
    }
}

And the complete aspx listing:

<%@ Page Language="C#" MasterPageFile="~/MasterPageGold.master"
AutoEventWireup="true" CodeFile="why.aspx.cs" Inherits="testThreads"
Title="Untitled Page" %>
<asp:Content ID="Content1"
ContentPlaceHolderID="ContentPlaceHolderForBody" Runat="Server">
    <br />
    <asp:Button ID="ButtonInitAsyncThread" runat="server" Text="init
async thread" OnClick="ButtonInitAsyncThread_Click"  />&nbsp;
    <asp:TextBox ID="TextBoxInParm" runat="server">78</asp:TextBox>
    <asp:Label ID="LabelThreadStatus" runat="server" Text="thread
status"></asp:Label><br />
    <br />
    <br />
    <asp:Button ID="ButtonCheckThreadStatus" runat="server"
Text="CheckThreadStatus" OnClick="ButtonCheckThreadStatus_Click" />
    <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>
</asp:Content>