C3p0 APPARENT DEADLOCK exception

Question

I keep getting this exception in my Tomcat log:

com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector run
WARNING: com.mchange.v2.async.ThreadPoolAs         


        

Answer 1

The tasks that are dealocking are Connection acquisition tasks. That is, c3p0 is trying to acquire new Connections from your database, and those Connection acquisition attempts are taking a long time.

The first thing I would do is upgrade to 0.9.2.1, which has a much improved means of performing a round of Connection acquisitions in situations where acquisition attempts sometimes fail.

If that doesn't solve your problem, then you'll need to figure out why c3p0's attempts to acquire a Connection are hanging for long periods of time: neither succeeding nor failing with an Exception.