多任务进程抛出异常

Question

我是使用多任务处理的新手。运行以下代码时，有一次例外。为什么会引发异常。

我给出了（对象引用未设置为对象实例的）异常。我正在寻找哪个对象抛出。但是我从来没有在使用多任务之前给出过例外。

代码：

 System.Threading.Tasks.Task[] tasks = new System.Threading.Tasks.Task[vw.Count];

            System.Collections.Concurrent.ConcurrentQueue<DataSet> dsCollection = new System.Collections.Concurrent.ConcurrentQueue<DataSet>();

            for (int i = 0; i < tasks.Length; i++)
            {
                tasks[i] = System.Threading.Tasks.Task.Factory.StartNew((Object obj) =>
                  {
                      DataRowView dr = obj as DataRowView;

                      if ((dr["MagicMasterView"].ToString() == "1") || (dr["MagicMasterView"] == System.DBNull.Value))
                      {
                          DataSet dsTmp = new DataSet();

                          List<SqlParameter> sqlParameters3 = new List<SqlParameter>();

                          sqlParameters3.Add(new SqlParameter("@MasterID", nMasterID));
                          sqlParameters3.Add(new SqlParameter("@UserID", nUserID));
                          sqlParameters3.Add(new SqlParameter("@FirmID", nFirmID));

                          SqlProcedureBuilder sqlProcedure3 = new SqlProcedureBuilder()
                          {
                              IsTransaction = false,
                              NTimeout = 180000,
                              Procedure = sProcedure + "_Fill",
                              UserID = nUserID,
                              SrcTable = sProcedure,
                              SqlParams = sqlParameters3
                          };

                          using (SqlExecutor sql = new SqlExecutor())
                          {
                              sql.Execute(sqlProcedure3, ref dsTmp);
                          }

                          sqlProcedure3.Dispose();

                          dsCollection.Enqueue(dsTmp);

                      }
                  }, vw[i]);

            }

            System.Threading.Tasks.Task.WaitAll(tasks);

            foreach (var item in dsCollection)
            {
                ds.Merge(item as DataSet, false);
            }

注意：SqlExecutor，SqlProcedureBuilders类已在db中执行了过程。