如何在多线程.NET应用程序中的单个表单上更新多个控件？

Question

I have a form that has six instances of a UserControl spread across three TabPages. Each UserControl contains a CheckedListBox that can contain a relatively large number of items (200k+). Retrieving and setting the data is done by calling into UpdateRecords in the below code:

private void UpdateRecords()
{
    List<Records> oRecords = ServerDataAccess.GetRecords(m_sConnectionString);

    Thread LoadRecords1 = new Thread(() => UserControl1.Records = oRecords);
    LoadRecords1.Start();

    Thread LoadRecords2 = new Thread(() => UserControl2.Records = oRecords);
    LoadRecords2.Start();

    Thread LoadRecords3 = new Thread(() => UserControl3.Records = oRecords);
    LoadRecords3.Start();
}

public List<Record> Records
{
    set
    {
        //Make deep copy of records so changes to records in one UserControl do not affect others
        AddRecordsToCheckedListBox(value.AsParallel().Select(oRecord => oRecord.Clone()).OrderBy(oRecord => oRecord.Name).ToArray());
    }
}

delegate void AddRecordsToCheckedListBoxDelegate(Record[] Records);
private void AddRecordsToCheckedListBox(Record[] Records)
{
    if (InvokeRequired)
    {
        Invoke(new AddRecordsToCheckedListBoxDelegate(AddRecordsToCheckedListBox), new object[] { Records });
    }
    else
    {
        clbRecords.SuspendLayout();
        clbRecords.Items.AddRange(Records);
        clbRecords.ResumeLayout();
    }
}

While creating the copies of the arrays, CPU usage spikes to 100%, as expected, but once the threads get to the point where they all start updating the controls with the data arrays, CPU usage is pegged at 50% (dual core system) due to needing to invoke the call, creating a bottleneck.

Currently, loading data takes approximately 3 minutes, and benchmarking indicated that at a minimum, about 2:00-2:30 of that time is spent executing clbRecords.Items.AddRange(Records); in AddRecordsToCheckedListBox. Each UserControl is functionally isolated from each other, so changes to one have no impact to any of the others, they do, however, need to remain on the same form.

Is there a way to load the array of records into each of these controls that takes advantage of having multiple cores available to reduce the bottleneck?

Answer 1

Updating the controls will be only on the UI thread, that will only use 1 core.

And apart from that, to achieve any efficiency in your program you should not try parallellism, but reducing your data. Eg not fill complete records, but only its Id, Name. That should be sufficient for the UI.

Probably you will also need paging, because 200k items in a checkedlistbox is not really user friendly.