Monitoring total number of JDBC connections

Question

We have our application deployed in the Oracle 10g Application server, it uses Toplink 10g for the Persistence and OR mapping and the Oracle 9i database for data storage, the database connection pool is built and maintained by Toplink.
We observed that on the administration screen for each container, there are 2 parameters, number of active database connections and the total number of JDBC connections.
We did some load testing for the application and observed the following behaviour on the container.
1. When the number of parallel users are 10, behaviour seems to be normal, the active database connections are less than 20(used by the connection pool built by Toplink) and the total number of JDBC connections is the same as the number of database connections.
2. When the number of parallel users is increased to 50, we see that the active database connections is still less than 20, but the total number of JDBC connections just blowed up to 4000+ in less than 2 minutes and still growing. We have no valid explanation for this behaviour as the active sessions is still less than 20. Also we see no obnormal behaviour in our application log files.
The questions i have are
1. What could be the reason for the above abnormal behaviour?
2. How this parameter "Total number of JDBC connections" for a container is actually measured?
3. DOes this parameter gets affected by how we run the database i.e. in Dedicated server mode or Despactcher mode?
Many thanks for any information on this topic..

Answer 1

Perhaps your connection inactivity timeout is slightly too low, so that your connections are being closed and reopened at almost the same frequency. Try increasing the timeout.
Good Luck,
Chris