Datatable updated by multiple threads yields datagrid problem

[Becker]

I have a datatable that I use to display running processes. These running
processes are spawned as different threads. I use the readerwriterlock
class to ensure that when I write to the datatable, I obtain a write lock.
The datagrid is set to have a datasource of the datatable.

The problem is that I get this error intermittently and it draws a big red X
across my datagrid:

************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an
object.
at System.Data.DataColumnPropertyDescriptor.GetValue(Object component)
at
System.Windows.Forms.DataGridColumnStyle.GetColumnValueAtRow(CurrencyManager
source, Int32 rowNum)
at System.Windows.Forms.DataGridTextBoxColumn.Paint(Graphics g, Rectangle
bounds, CurrencyManager source, Int32 rowNum, Brush backBrush, Brush
foreBrush, Boolean alignToRight)
at
System.Windows.Forms.DataGridRelationshipRow.PaintCellContents(Graphics g,
Rectangle cellBounds, DataGridColumnStyle column, Brush backBr, Brush
foreBrush, Boolean alignToRight)
at System.Windows.Forms.DataGridRow.PaintData(Graphics g, Rectangle
bounds, Int32 firstVisibleColumn, Int32 columnCount, Boolean alignToRight)
at System.Windows.Forms.DataGridRelationshipRow.Paint(Graphics g,
Rectangle bounds, Rectangle trueRowBounds, Int32 firstVisibleColumn, Int32
numVisibleColumns, Boolean alignToRight)
at System.Windows.Forms.DataGrid.PaintRows(Graphics g, Rectangle&
boundingRect)
at System.Windows.Forms.DataGrid.PaintGrid(Graphics g, Rectangle
gridBounds)
at System.Windows.Forms.DataGrid.OnPaint(PaintEventArgs pe)
at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e,
Int16 layer, Boolean disposeEventArgs)
at System.Windows.Forms.Control.WmPaint(Message& m)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg,
IntPtr wparam, IntPtr lparam)

Appears to be a problem with the datagrid. These threads run at the same
time updating this datatable after acquiring a lock, but what I'm not sure
is what effect this has on the datagrid since it auto-refreshes when the
datatable changes. I'm new to threading so any ideas or suggestions here
is greatly appreciated.

Thanks,
Ben

 

[Ajay Kalra]

Have you looked at the following:

http://support.microsoft.com/kb/318607/EN-US/

This shows how to update datagrid from a worker thread.