Question

I am trying to run a console process against each country. All the countries are in a datatable. Since the process for each country took 3-4 days. I have decided to run 4 countries at the same time to consume all 4 four processor of my quad core machine.

I write the above code, but the problem with this code is, it runs all the thread at the same time. I want a maximum of 4 thread simultaneously and the rest wait for their turn. I don’t mind if the application stuck in country loop and wait for the threads to be finished and start next thread immediately.

private void Form1_Load(object sender, EventArgs e) 
{
    DataTable dt = new DataTable("Countries");

    #region DataProcessing
    DataColumn dc1 = new DataColumn();
    dc1.DataType = System.Type.GetType("System.Int32");
    dc1.ColumnName = "CountryID";

    DataColumn dc2 = new DataColumn();
    dc2.DataType = System.Type.GetType("System.String");
    dc2.ColumnName = "CountryName";

    dt.Columns.Add(dc1);
    dt.Columns.Add(dc2);

    DataRow dr = dt.NewRow();
    dr["CountryID"] = 1;
    dr["CountryName"] = "US";
    dt.Rows.Add(dr);

    //similar code...

    dr = dt.NewRow();
    dr["CountryID"] = 20;
    dr["CountryName"] = "KR";
    dt.Rows.Add(dr);
    #endregion

    ThreadPool.SetMaxThreads(5, 5);

    foreach (DataRow drLoop in dt.Rows) 
    {
        Thread job = new Thread(new ParameterizedThreadStart(ThreadJob), 5);
        job.Start(drLoop["CountryName"].ToString());
    }
}
static void ThreadJob(Object country) 
{
    //Do Something
    MessageBox.Show(country.ToString());
}

Answer 1

You are not using the ThreadPool- you are just starting up a Thread for each country:

foreach (DataRow drLoop in dt.Rows) 
{
    Thread job = new Thread(new ParameterizedThreadStart(ThreadJob), 5);
    job.Start(drLoop["CountryName"].ToString());
}

Try this instead:

foreach (DataRow drLoop in dt.Rows) 
    ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadJob), drLoop["CountryName"].ToString());