Does anyone have any recommendations over which connection pool is 'better'? We've been using c3p0 but it seems to repeatedly spawn asynchronous threads to test the connection to the database. I've experimented with dbcp and have noticed the memory usage of our web app increase over time but I'm unable to pin down why this is happening. It also seems to me that dbcp want to use more memory than c3p0.

Any comments?

you can change your parameters....

i don't know if dbcp always have bugs but we recommend c3p0 or proxool

Hi.

Connection tests are usually performed asynchronously by c3p0, but Threads to do so are not spawned continually. Checking of idle Connections is performed by the thread of a java.util.Timer; checking of Connections on check-in are performed by c3p0's pool of helper Threads (three big by default, but configurable); checking of Connections on checkout or when an Exception occurs is synchronous in the client thread.

If you are seeing threads creation by c3p0 beyond a small fixed number (typically between 3 and 6), that means something unusual is going on. One-off threads are only spawned by c3p0 when all pools in its thread pool are apparently blocked or deadlock, a situation which would be verbosely indicated in your logs.

smiles,
Steve (c3p0 guy)