Parallel ForEach on DataTable

i would like to use the new Parallel.ForEach function to loop through a datatable and perform actions on each row.

Example:

Normal foreach loop
foreach (DataRow dr in objDS.Tables[0].Rows)
{
if (!objHT.Contains(dr["MessageKey"].ToString()))
objHT.Add(dr["MessageKey"].ToString(), dr["MessageValue"].ToString());
}

Parallel.ForEach loop for above DataTable
Parallel.ForEach(objDS.Tables[0].AsEnumerable(), dr =>
{
if (!objHT.Contains(dr["MessageKey"].ToString()))
objHT.Add(dr["MessageKey"].ToString(), dr["MessageValue"].ToString());
});