sqlhelper - 连接从未关闭

Question

我一直在使用sqlhelper类，但是在系统中的用户活动数量增加后我遇到了问题。托管公司提到该网站已经在服务器的CPU上产生了沉重的负担。看来正在为您的数据库erkaner_slearning打开大量连接，并且它们继续生成负载，因为这些连接永远不会被关闭。下面是sqlhelper类。您对以下代码有什么建议吗？我找不到任何需要在下面明确关闭任何连接的地方。

public abstract class SqlHelper
{

    public static readonly string ConnectionString = ConfigurationManager.ConnectionStrings["sLecturing_ConnectionString"].ConnectionString;

    private static Hashtable parmCache = Hashtable.Synchronized(new Hashtable());

    public static int ExecuteNonQuery(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
    {

        SqlCommand cmd = new SqlCommand();

        using (SqlConnection conn = new SqlConnection(connectionString))
        {
            PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
            int val = cmd.ExecuteNonQuery();
            cmd.Parameters.Clear();
            return val;
        }
    }

    public static int ExecuteNonQuery(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
    {
        SqlCommand cmd = new SqlCommand();

        PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
        int val = cmd.ExecuteNonQuery();
        cmd.Parameters.Clear();
        //connection.Close();
        return val;
    }

    public static int ExecuteNonQuery(SqlTransaction trans, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
    {
        SqlCommand cmd = new SqlCommand();
        PrepareCommand(cmd, trans.Connection, trans, cmdType, cmdText, commandParameters);
        int val = cmd.ExecuteNonQuery();
        cmd.Parameters.Clear();
        //trans.Connection.Close();
        return val;
    }

    public static SqlDataReader ExecuteReader(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
    {
        SqlCommand cmd = new SqlCommand();
        SqlConnection conn = new SqlConnection(connectionString);

        // we use a try/catch here because if the method throws an exception we want to 
        // close the connection throw code, because no datareader will exist, hence the 
        // commandBehaviour.CloseConnection will not work
        try
        {
            PrepareCommand(cmd, conn, null, cmdType, cmdText, commandParameters);
            SqlDataReader rdr = cmd.ExecuteReader(CommandBehavior.CloseConnection);
            cmd.Parameters.Clear();
            return rdr;
        }
        catch
        {
            conn.Close();
            throw;
        }
    }

    public static object ExecuteScalar(string connectionString, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
    {
        SqlCommand cmd = new SqlCommand();

        using (SqlConnection connection = new SqlConnection(connectionString))
        {
            PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
            object val = cmd.ExecuteScalar();
            cmd.Parameters.Clear();
            return val;
        }
    }

    public static object ExecuteScalar(SqlConnection connection, CommandType cmdType, string cmdText, params SqlParameter[] commandParameters)
    {

        SqlCommand cmd = new SqlCommand();

        PrepareCommand(cmd, connection, null, cmdType, cmdText, commandParameters);
        object val = cmd.ExecuteScalar();
        cmd.Parameters.Clear();
        //connection.Close();
        return val;
    }

    /// <summary>
    /// add parameter array to the cache
    /// </summary>
    /// <param name="cacheKey">Key to the parameter cache</param>
    /// <param name="cmdParms">an array of SqlParamters to be cached</param>
    public static void CacheParameters(string cacheKey, params SqlParameter[] commandParameters)
    {
        parmCache[cacheKey] = commandParameters;
    }

    /// <summary>
    /// Retrieve cached parameters
    /// </summary>
    /// <param name="cacheKey">key used to lookup parameters</param>
    /// <returns>Cached SqlParamters array</returns>
    public static SqlParameter[] GetCachedParameters(string cacheKey)
    {
        SqlParameter[] cachedParms = (SqlParameter[])parmCache[cacheKey];

        if (cachedParms == null)
            return null;

        SqlParameter[] clonedParms = new SqlParameter[cachedParms.Length];

        for (int i = 0, j = cachedParms.Length; i < j; i++)
            clonedParms[i] = (SqlParameter)((ICloneable)cachedParms[i]).Clone();

        return clonedParms;
    }

    /// <summary>
    /// Prepare a command for execution
    /// </summary>
    /// <param name="cmd">SqlCommand object</param>
    /// <param name="conn">SqlConnection object</param>
    /// <param name="trans">SqlTransaction object</param>
    /// <param name="cmdType">Cmd type e.g. stored procedure or text</param>
    /// <param name="cmdText">Command text, e.g. Select * from Products</param>
    /// <param name="cmdParms">SqlParameters to use in the command</param>
    private static void PrepareCommand(SqlCommand cmd, SqlConnection conn, SqlTransaction trans, CommandType cmdType, string cmdText, SqlParameter[] cmdParms)
    {
       // bool mustCloseConnection = false;

        if (conn.State != ConnectionState.Open)
        {
            conn.Open();
        }

        cmd.Connection = conn;
        cmd.CommandText = cmdText;

        if (trans != null)
            cmd.Transaction = trans;

        cmd.CommandType = cmdType;

        if (cmdParms != null)
        {
            foreach (SqlParameter parm in cmdParms)
                cmd.Parameters.Add(parm);
        }


    }
}