Running out of DB connections!

Question

I\'m running a Spring/Hibernate connecting to MySQL setup using c3p0 as my connection pool. For some bizarre reason it runs out of connections when the system is under load (of

Answer 1

It's pretty unlikely that @Transactional leaks connections - otherwise, your site would stop working after the first 100 requests.

But there is another reason why this happens:

Maybe you have set a timeout for "dead" connections and some queries take longer than that. That means that your pool removed a busy connection as "dead" from the pool and requests another from the DB - until the DB pulls the plug.

To debug this, enable logging for your connection pool, so you can see when it requests new connections.