Web服务中的多线程加速了处理速度

我确实有一个桌面程序的业务逻辑处理。

然而，当我处理大数据时，数据处理速度非常慢(我使用的是MS SQL数据库)。因此，我做了一个工作。我打开一个web服务项目，并将我的业务逻辑过程打包到一个名为consoleAttn()的dll中，然后使用DotNet Task将处理分离为几个线程。并行技术的代码如下:

`

    DataTable dtEmp = new DataTable("Employee");
    if (cn.State == ConnectionState.Closed)
    {
        cn.Open();
    }
    using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(sEmpQuery, cn))
    {
        Console.Write(string.Format("Command Text:{0}", sEmpQuery));
        cmd.Parameters.AddWithValue("Period", sPeriod);
        dtEmp.Load(cmd.ExecuteReader());
    }
    if (cn.State == ConnectionState.Open)
    {
        cn.Close();
    }
    Int32 iThread;
    iThread = iNoThread;
    Int32 iCountTable;
    iCountTable = dtEmp.Rows.Count;
    Console.WriteLine(string.Format("Total Rows:{0}", iCountTable));
    Int32 IProcNum;
    IProcNum = iCountTable / iThread;
    Console.WriteLine(string.Format("Transaction no:{0}", IProcNum));

    if (iCountTable < iThread)
    {
        Boolean bl;
        AutoHRPay.frmClosePeriod aPay= new AutoHRPay.frmClosePeriod();
        MiscResource AMisc = new MiscResource();
        MiscResource misc = new MiscResource();
        misc.SetDBConn(strCN);

    }
    else
    {
        Boolean[] bl = new Boolean[iThread];
        object locker = new object();
        Parallel.For(1, iThread + 1, i =>
        {
            System.Text.StringBuilder strSQL = new System.Text.StringBuilder();
            strSQL.Append("(");
            DataTable dtEmpThread = dtEmp.Clone();
            dtEmpThread.Clear();
            for (Int32 j = ((i - 1) * IProcNum + 1); j <= ((i != iThread) ? (IProcNum * i) : iCountTable); j++)
            {
                dtEmpThread.ImportRow(dtEmp.Rows[j-1]);
            }

            int row_counter = 0;
            lock (locker)
            {
                row_counter++;
                streamwriter.WriteLine("Processing row: {0}", row_counter);
            }

            ConsoleAttn aPay = new ConsoleAttn();
            aPay.runConsole();
        });

    }
    streamwriter.Close();
    return "Completed.";

1)你有任何想法，当我需要停止进程或当客户端调用web服务崩溃时，我应该如何做异步进程?