Improve connection pool recovery logic


Improve the connection pool recovery logic if possible. More info at:




Daniel Henninger
March 26, 2008, 8:33 PM

There's an improvement coming to the current pool implemention in RC2.

James Mc Millan
March 26, 2008, 8:28 PM

Hi Guys

Just to let you know, we upgraded to 3.5.0rc1 from 3.3.2 and we had major issues with the Proxool connection pooling, and we had to give it an unreasonably high number of connections in order for it to work (most of the time). It seems to hold onto connections for longer than it should and not release them.

The good news is switching to c3p0 (an easy implementation of ConnectionProvider) solved the problem for us. So, if anyone else has problems, switching to c3p0 is simple enough. At the moment though, we don't have statistics on the database page, which throws an exception as it is hardcoded to look for Proxool.


Daniel Henninger
January 15, 2008, 12:24 AM

Hrm. Good point. I had planned on doing that "in the future" but might as well do it now instead of using the servlet. =)

BTW I ran your test and wow. it didn't miss a beat! (I took down MySQL, almost immediately did it detect problems, things broke, etc, and then I started MySQL back up and it immediately was happy again) I also did a rude test -> i kill -9'd mysql out from under openfire and it didn't detect the mysql shutdown immediately in terms of .. immediately show that mysql died, but the first database request caught it. (and I imagine the every 30 second check would have seen it) Brought up MySQL, all is well again immediately.

I'm quite pleased with it's behavior!

I'll look into improving the servlet.

BTW, looks like the ClearSpace folk aren't particularly interested for now, sounds like they solved their problems with their stuff. Bruce did tell me that JNDI has some sort of it's own connection pooling, but I'm not sure it has the powerful connection testing that this has. (proxool is testing the connection before and after it's used to see if it's still a valid connection, it seems to be very robust in that sense ... the caveat of course is that' it's doing extra "SELECT 1" commands, but I explicitly picked something super quick like that so it shouldn't be a noticable performance hit.

Speaking of which, at some point I'd like to investigate where we could use some indexes and such to improve our database interactions altogether. Guus found at least one instance where we were missing a possible important index that sped things up quite a bit.

January 14, 2008, 3:18 PM

Rather than include the web servlet, it seems like it would be much better to incorporate that same data into the existing database page.

Daniel Henninger
January 14, 2008, 12:04 PM

Hi Matt! I actually already am including the web servlet! Though now that you mention it, I might need to make a config tweak to trigger the graphing to actually occur. Good test suggestion!



Daniel Henninger