Database connection pooling and pool size questions

[Blama]

Hi Isomorphic,

I ran into a problem yesterday were I could not connect to my DB using Oracle SQL Developer, but the application (SmartGWT 6.1p) was still running.
Exception was like here ("ORA-12519 TNS: no appropriate handler found"). I assume this is because I'm running a per-customer war of my application and those slowly reach the maximum amount of connections the DB accepts.

I have some questions here:

1. Is there a pool size settings and if so, where? I did not see one in server.properties nor in isomorphic_core_rpc.jar -> framework.properties.
2. Is it perhaps maxActive, maxIdle and maxWait? If so, how do these work together? How would I configure a system to allow a maximum of e.g. 10 connections (per instance/war of course)?
3. What number of connections do you suggest (low-load SaaS, only a few (less than 5) concurrent users), if that's possible for you to do. Is there a lower threshold you would never cross?
4. What happens if whenExhaustedAction: grow gets a DB exception like the one I got?

Thank you & Best regards
Blama

[Blama]

PS: I saw these two related threads, that have the same issue. Of course one could just configure Oracle to accept 1000 connections, but this will also cause problems eventually (with more wars deployed), so the answers to those questions are relevant to me.

Another question: If there are spikes in usage, will you keep those connections open or close them again after some time?

Best regards
Blama

[Isomorphic]

It looks like you found the properties, but not the docs, which are here. It looks like this doc covers all your questions (at least, in combination with Apache DBCP docs).

We would guess that running out of connections in your case may indicate a connection leak, or some process that ends up borrowing a lot of connections concurrently, possibly unnecessarily.

[Blama]

Hi Isomorphic,

thanks, I'll have a look at the docs, as I did not see them before, like you assumed.

Best regards
Blama