Our site get roughly 1M pv/day, and we use Tomcat for sure.
I couldn\'t find much information about jdbc-pool, not sure if it\'s stable enough for production. Anyone
I'm one of the authors of HikariCP. That said, the "new" Tomcat pool is among the best we've tested. It has a lot of options, so if you plan to use it in production make sure you understand them to get a reliable configuration.
Do not confuse the new Tomcat pool with Apache DBCP, which I would avoid.
We are starting the process of abuse testing various pools, including HikariCP, with tests such as bouncing the DB underneath the pool and measuring the resulting recovery. Check out site for results in the coming weeks.
EDIT: Re: HikariCP being too young. Young though it may be it has had several billion transactions run through it. As with anything, I would suggest you try it in a pre-production environment before deployment. But the same goes for any pool you might choose.
UPDATE 2015-06-01: I want to revise my statement above somewhat, it seems that Apache Commons DBCP is active once again, and has taken over for the dedicated/forked Tomcat DBCP. The refactors in Commons DBCP appear at first glance to be significant, and positive. However, due to their magnitude and despite being under the old Commons DBCP banner, I would characterize the pool as less mature than HikariCP at this point.