Setting "QUEUESIZE" parameter solve "Concurrency Problem"

Hi everyone, I recently ran into a concurrency problem on Oracle 7.3.4 for which I couldn't find an obvious solution. A call to Oracle Tech Support resolved the issue, and I'm posting the solution below in case anyone else runs into a similar problem.

Basically, the issue was that the Oracle server kept returning "ORA-12203: TNS Unable to connect to destination" when I loaded it down with a lot of concurrent connection requests. When the requests were sent from slower clients the problem appeared less often than when the requests were sent from fast clients. This indicated that the speed with which the connection requests were being sent was causing the problem, which therefore indicated that there was a concurrent connection problem on the Oracle server.

The problem, as it turned out, was that the QUEUESIZE parameter was not set correctly. This parameter essentially governs the number of concurrent connections that the Oracle server can support, and it was set too low for my purposes. By bumping this parameter up to about 200, the problem disappeared. The server suffered a slight performance hit in the process, but at least the concurrency issue is resolved.

The material sent to me from Oracle Tech Support follows:

Example:
Set "QUEUESIZE" in listener.ora file, here is a sample of the ADDRESS_LIST in the LISTENER.ORA file:

LISTENER =

     (ADDRESS_LIST =
       (ADDRESS =


        (PROTOCOL = TCP)

        (HOST = prodserv)

        (PORT = 1521)

        (QUEUESIZE = 200)

       )
      )

Description:

The (QUEUESIZE=n) name-value pair enables the listener to increase its listening queue [or backlog] in order to dynamically handle large numbers of concurrent connect requests. This NVpair can be added to an (ADDRESS=) NVstring that describes any listening endpoint within listener.ora. Received on Fri Sep 11 1998 - 00:00:00 CDT