Hi,

I just migrated my project (tomcat/hib/c3p0/mysql) from hibernate 2 to hibernate 3.1.3.
Now I wonder which c3p0 version I should use considering primarily the stability of the application.

c3p0-0.9.0:
Comes with the hibernate 3.1.3 release (and even with the newest 3.2.CR4), which I would interpret as a form of recommendation. But for sure this c3p0 version has (at least minor) bugs which are fixed in later versions.

c3p0-0.9.0.4:
Contains bugfixes for the former 0.9.0.x versions. But this version still seem to have some critical problems, e.g.:

• http://opensource.atlassian.com/projects/hibernate/browse/HHH-2032
• http://sourceforge.net/tracker/index.php?func=detail&aid=1544159&group_id=25357&atid=383690

c3p0-0.9.1-pre7:
May contain bugfixes, e.g. for the problems above, but I'm not really thrilled to use a pre-release in a productional environment.

Any recommendations / experiences / opinions / thoughts?

Andreas

First, sorry for the dilemma... I wish you didn't feel you faced so many tradeoffs.

The issue that was of most practical significance in c3p0-0.9.0.4 (and which is only just resolved in c3p0-0.9.1-pre7) has to do with the interaction between Connection close() and the statement pool. If you don't use statement caching (hibernate.c3p0.max_statements=0), you're not likely to see this. If there's a clamour for it, I could backport the fix. The other issue you cite (pool size dropping below its minimum, eventually to zero, and not recovering) was very rarely reported (at least to me), and was resolved in the c3p0-0.9.1-pre series by a significant rewrite of pool size management, which would be a more disruptive backport. Both issues are embarrassing, but rare (and c3p0 recovers from the stmt-cache-related deadlock). c3p0-0.9.0.4 is not a bad choice, with statement caching disabled for maximum stability.

That said, c3p0-0.9.1-pre7 resolves these and many other issues, as well as adding new features. It's brand new, though. I've had too little feedback to affirm it's stability, although I think it will be. -pre6 has had a lot of use, and resolves the pool sizing issue, but not the stmt-cache deadlock.

One nice thing about c3p0 is that you really don't have to commit. (no pun intended...) I'd encourage you to try the latest, and I'll bet it works great for you. If not, please embarrass me with a detailed report of what went wrong, and take solace in that changing versions is nothing more than replacing a jar file.

Good luck!
Steve