I have a .Net service application that interfaces with our production
database (v7.6.0.12 on a separate server under Solaris 9) using the ODBC
data provider (System.Data.Odbc) in .Net framework v1.1.4322. I'm using
the Windows MaxDB ODBC driver version 7.6.0 b016 (MDAC 2.81.1117.0) with
Connection Pooling enabled. The service appears to leak memory whenever
the load increases to the point where it must open further data base
connections. When the load decreases and these extra connections are
not needed the connection pool begins closing these sessions, however
not all the memory appears to be released.
As an experiment, I wrote the following simple application and observed
that its memory footprint also continues to increase over time. The
application repeatedly opens a connection; calls a stored procedure and
retrieves the results; and then pauses long enough for the connection
pool to close the connection. I have used the "using" clause to ensure
there are no connection leaks. Does anyone have any suggestions?
using System;
using System.Data.Odbc;
namespace TestApp
{
class TestApp
{
[STAThread]
static void Main(string[] args)
{
for (int i = 0; i < 1000; i++)
{
try
{
using(OdbcConnection dbconn = new
OdbcConnection("DSN=GWDB_T;UID=<user>;PWD=<pwd>"))
{
dbconn.Open();
using(OdbcCommand dbcmd = new OdbcCommand("CALL DBA.SP251_GETSTATUS
(?,?,?,?)",dbconn))
{
dbcmd.CommandType = System.Data.CommandType.StoredProcedure;
dbcmd.Parameters.Add("I_DEVICESERIALNUM",Convert.ToDouble("000020"));
dbcmd.Parameters.Add("O_ISACTIVE", OdbcType.Char, 1);
dbcmd.Parameters["O_ISACTIVE"].Direction =
System.Data.ParameterDirection.Output;
dbcmd.Parameters.Add("O_DEVICESERIALNUM", OdbcType.Double);
dbcmd.Parameters["O_DEVICESERIALNUM"].Direction =
System.Data.ParameterDirection.Output;
dbcmd.Parameters.Add("O_RETCODE", OdbcType.Char, 10);
dbcmd.Parameters["O_RETCODE"].Direction =
System.Data.ParameterDirection.Output;
int rc = dbcmd.ExecuteNonQuery();
string o_isactive = dbcmd.Parameters["O_ISACTIVE"].Value.ToString();
string o_deviceserialnum =
dbcmd.Parameters["O_DEVICESERIALNUM"].Value.ToString();
string o_retcode = dbcmd.Parameters["O_RETCODE"].Value.ToString();
} // using dbcmd - should automatically dispose command object
} // using dbconn - should automatically dispose connection object
}
catch
{
}
finally
{
/* Pause application long enough for Connection Pool to close previous
connection, in this case I have set the time that unused connections
remain in pool to 10 seconds */
System.Threading.Thread.Sleep(15000);
}
} // for loop
} // End of Main
}
}
Terry Gifford
Tacoma Power - Advanced Metering Project
