测试C＃MySQL连接池失败并显示以下异常：连接必须有效且打开

Question

I am trying to use connection pooling on MySQL's .net connector 6.6.4.0 to serve multiple threads using the code below:

static public uint uNonQuery(string query)
        {

                using (Connection = new MySqlConnection(ConnectionString))
                {
                    if (Connection.State == ConnectionState.Open)
                    {
                        Console.WriteLine("Its open..>!!!!");
                    }

                    Connection.Open();

                    MySqlCommand cmd = new MySqlCommand(query, Connection);
                    cmd.ExecuteNonQuery();


                    MySqlDataAdapter adapter = new MySqlDataAdapter("SELECT LAST_INSERT_ID() AS 'identity'", Connection);
                    DataTable dt = new DataTable();
                    adapter.Fill(dt);
                    uint ret = 0;

                    if (dt.Rows.Count > 0)
                    {
                        try
                        {
                            ret = Convert.ToUInt32(dt.Rows[0]["identity"]);
                        }
                        catch
                        {
                            ret = 0;
                        }
                    }

                    else
                        ret = 0;

                    Connection.Close();
                    return ret;
                }
        }

My connection string is

"server = 127.0.0.1; user id = ****; password = ****; database = testdb; pooling=true; maximumpoolsize=500;"

And the thread for testing is

static void DoInserts(object o)
{
    int i = (int)o;
    Console.WriteLine("Insert Thread {0} launched", i);


    for(int x = 0; x < 1000; x++)
    {
        uint insertId = DataLayer.uNonQuery(String.Format("INSERT INTO testdb.dbtest (writeNo,strNo) VALUES ({0},'x={0} thread={1}')", x, i));
    }

    Console.WriteLine("Insert Thread {0} completed", i);

}

I get the exception Exception: Connection must be valid and open. after about 6 inserts on 2 concurrent threads, is there something else i need to do enable pooling to work correctly?

Thanks

Answer 1

In your line using (Connection = new MySqlConnection(ConnectionString)) you are using the variable Connection . Where is this variable defined? Is it static? You should define it in scope of uNonQuery . If variable Connection is static, then it is possible the connection is closed after a new function call to uNonQuery has opened it.

Example: - Thread 1 calls uNonQuery and opens, does it things. - Thread 2 calls uNonQuery , opens the connection, - Thread 1 closes Connection - Thread 2 cannot do its thing because the connection was suddenly closed.

If the above is not the cause of your problem I would need more of your code to examine the problem.