How many processes can a Oracle 9i Release 2 Listener support?

How many processes can a Oracle 9i Release 2 Listener support?  I realized there are variables to this question such as server hardware configuration and such, I just need a reasonable guess.

Our environment has 20+ Java applications accessing our database and performing selects, inserts, and updates to server tables.  We currently have only one listener created for the instance.  I am concerned that there may be a performance issue.  If someone can provide some guidelines I would appreciate it.

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schwertnerConnect With a Mentor Commented:
Oracle says that every process needs about 5MB RAM. Practically I estimate it about 2MB per process.
This is the only reasonable limitation of the number of the processes.

You will noit have problems with the Listener itself.
The real problem are the dead sessions that are often produced by Java and other
front-end applications. This means processes connected to canceled applications.
Oracle keeps these processes open and the result is very bad.

To avoid this you can force the listener to close dead sessions in a
period of time. To do this in SQLNET.ORA set

This will cause every 30 minutes investigaten of the sessions and
deletion of all dead sessions.
BobMcConnect With a Mentor Commented:
The listener is only used for the initial connection, it then starts up a user process, and hands off the client connection to it. Your apps can do as much DML as they want - it wont bother your listener!

Any limitation would only be in the number of concurrent connections (listener requests). I believe these will queue up if the listener is struggling to service them all. In any case, you can pre-spawn listener connections (takes longer at startup), so I would imagine the limit will never be reached in practise.

I always use one listener per instance, or even one per database server for smaller systems

andertstConnect With a Mentor Commented:
The only time I have not used a single listener per DB server is when a bug forces my hand.  There were a few bug with 8i and certain OS's (Tru64 I know of) but I think with the latest 8i releases they were fixed.  Have not run into any problem with 9i or 10g listeners, although 10g has been limited to play-time and research at home.  The 9i listeners have supported 20+ instances with a single listener with no problem.

You will only have problems if there are more concurrent connections than listener can handle.  I agree with Bob that it is unlikely to reach that for many systems, but the web changes everything so if you are deploying web-based apps, make sure you build test scenarios for hundreds or thousands of concurrent logins at the same time.

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