DBCP seems to be a safe bet: <a href="http://wix.io/2013/06/12/how-many-threads-does-it-take-to-fill-a-pool/" rel="nofollow">http://wix.io/2013/06/12/how-many-threads-does-it-take-to-fi...</a><p>But I think the new connection pool in Tomcat might be interesting as well.