How to handle multiple SQL transactions through different .net(c#) threads

Question

I have the following method for bulk insert of the data in tables. First my code populates the data in data tables and inserts this data in corresponding tables using the SqlBulkCopy claas of the .net .

I have requirement that data should get inserted in all tables or neither of them. For this I have used SqlTransaction class of the .net.

Scenario is, multiple threads execute the following code block at the same time.

 public void Import()
        {
            using (SqlConnection sqlConnection = new SqlConnection(connectionString))
            {

                SqlTransaction sqlTrans =null;
                try
                {
                    sqlConnection.Open();
                    sqlTrans = sqlConnection.BeginTransaction(IsolationLevel.Serializable)


                    SqlCommand cmd = sqlConnection.CreateCommand();
                    cmd.CommandText = "select top 1 null from lockTable with(xlock)";
                    cmd.CommandTimeout = 3600*3;
                    cmd.Transaction = sqlTrans;
                    SqlDataReader reader = cmd.ExecuteReader();


                    foreach (DataTable dt in DataTables)
                    {
                        ImportIntoDatabase(sqlConnection, dt, sqlTrans);
                    }

                    reader.Close();
                    sqlTrans.Commit();                    
                }
                catch (Exception ex)
                {
                    sqlTrans.Rollback();
                    throw ex;
                }
            }
        }

       private void ImportIntoDatabase(SqlConnection sqlConn, DataTable dt, SqlTransaction sqlTrans)
        {
            using (SqlBulkCopy bulkCopy = new SqlBulkCopy(sqlConn, SqlBulkCopyOptions.Default, sqlTrans))
            {
                bulkCopy.BulkCopyTimeout = dt.Rows.Count * 10;
                try
                {
                    bulkCopy.DestinationTableName = dt.TableName;                    
                    bulkCopy.WriteToServer(dt);
                }
                catch (Exception ex)
                {
                   throw ex;
                }
            }
        }

To handle this concurrency, I have created one dummy table(table named 'lockTable'), in the database where the other table resides(the bulk insert tables). I am getting exclusive lock on this dummy table in the SqlTransaction having command time out as high as 3 hours.

Problem: I am getting following exception

: Cannot access destination table 'Tbl1' (tbl1 is the table for bulk inserting)

followed by another exception, while rolling back the transaction in catch block

: Error While executing activity The server failed to resume the transaction. Desc:3a00000001. The transaction active in this session has been committed or aborted by another session.

Can any one help me for this weird behavior of the code. I have already searched a lot on this issue on the internet, but I have not found anything helpful for me.

Answer 1

I got my problem solved out.

Following are the changes which I have made to my Import method

public void Import()
        {
            using (SqlConnection sqlConnection = new SqlConnection(connectionString))
            {
                sqlConnection.Open();
                using (SqlTransaction sqlTrans = sqlConnection.BeginTransaction())
                {
                    try
                    {                       
                        SqlCommand cmd = sqlConnection.CreateCommand();
                        cmd.CommandText = "select top 1 null from lockTable with(xlock)";
                        cmd.CommandTimeout = LOCK_TIME_OUT;
                        cmd.Transaction = sqlTrans;
                        SqlDataReader reader = cmd.ExecuteReader();


                        foreach (DataTable dt in DataTables)
                        {
                            ImportIntoDatabase(sqlConnection, dt, sqlTrans);                            
                        }

                        reader.Close();
                        sqlTrans.Commit();                        
                    }
                    catch (Exception ex)
                    {
                        sqlTrans.Rollback();
                        throw ex;
                    }
                }
                sqlConnection.Close();
            }
        }