Question

Question:

Why is the following code leaking connections ?

    public System.Data.DataTable GetDataTable()
    {
        System.Data.DataTable dt = new System.Data.DataTable();
        string strConnectionString = "Data Source=localhost;Initial Catalog=MyDb;User Id=SomeOne;Password=TopSecret;Persist Security Info=False;MultipleActiveResultSets=False;Packet Size=4096;";
        System.Data.SqlClient.SqlConnectionStringBuilder csb = new System.Data.SqlClient.SqlConnectionStringBuilder(strConnectionString);
        csb.IntegratedSecurity = true;


        string strSQL = "SELECT * FROM T_Benutzergruppen";

        using (System.Data.SqlClient.SqlConnection sqlcon = new System.Data.SqlClient.SqlConnection(csb.ConnectionString))
        {
            using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(strSQL, sqlcon))
            {
                if (sqlcon.State != System.Data.ConnectionState.Open)
                {
                    sqlcon.Open();
                }

                // First attempt
                //System.Data.SqlClient.SqlDataAdapter sqlda = new System.Data.SqlClient.SqlDataAdapter("SELECT * FROM T_Benutzer", sqlcon);
                //sqlda.Fill(dt);

                cmd.ExecuteNonQuery();
            }

            if(sqlcon.State != System.Data.ConnectionState.Closed)
                sqlcon.Close();
        }
        //sqlcon.ConnectionString = csb.ConnectionString;

        // Second attempt
        //System.Data.SqlClient.SqlDataAdapter sqlda = new System.Data.SqlClient.SqlDataAdapter("SELECT * FROM T_Benutzer", csb.ConnectionString);
        //sqlda.Fill(dt);


        return dt;
    }

If I go into SQL-Server activity monitor, I see Session 68

SELECT * FROM T_Benutzergruppen

Additional question:

If question:

If I comment out everything except the ConnectionStringBuilder, and only execute the below code in this function, why does it leak a connection, too ?

// Second attempt
System.Data.SqlClient.SqlDataAdapter sqlda = new System.Data.SqlClient.SqlDataAdapter("SELECT * FROM T_Benutzer", csb.ConnectionString);
sqlda.Fill(dt);

Note:
The executenonquery makes no sense, it’s just there for testing purposes.

If I let it run in the debugger, I see that
sqlcon.Close();

get’s executed, so the problem is not the

if(sqlcon.State != System.Data.ConnectionState.Closed)

Answer 1

Connection Pooling. Don’t worry about it.

This is normal behavior.

http://msdn.microsoft.com/en-us/library/8xx3tyca(v=vs.100).aspx