Hi there,

I am running my app on Jetty 5.1.4, with Hibernate 2.1.8 and c3p0 0.9.1-pre12. I am intermittently seeing my application hanging. A scroll through the logs turns up the following:

com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@167c26f -- APPARENT DEADLOCK!!! Creating emergency threads for unassigned pending tasks!

and sometimes, also:
com.mchange.v2.async.ThreadPoolAsynchronousRunner$DeadlockDetector@167c26f -- APPARENT DEADLOCK!!! Complete Status:
Managed Threads: 3
Active Threads: 3
Active Tasks:
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@151c72f (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1ec0c79 (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@26dfff (com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1)
Pending Tasks:
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@3bebc2
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@1f34618
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@7ee20b
Pool thread stack traces:
Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2,5,main]
com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1026)
com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0,5,main]
com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1026)
com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
Thread[com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1,5,main]
com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1026)
com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)

I am at a lost as to what can be going wrong. What would typically be the cause of this?

I have browsed through some other posts on this issue (e.g. http://forum.hibernate.org/viewtopic.ph ... dlock+c3p0), but still have no luck.

Any help is much appreciated!

Thanks.

Hi,

For some reason, c3p0's attempts to acquire a database Connection are neither succeeding nor failing with an Exception, but are instead hanging. Your first order of debugging should be to try to figure out why that might be. Does this occur after some unusual condition, a network outage or DB restart? Why is your JDBC driver hanging rather than failing?

If you want a workaround, try the c3p0 config parameter maxAdministrativeTaskTime. This will cause c3p0 to try to interrupt threads that seem to hang during Connection acquisitions, destructions, or asynchronous Connection tests rather than waiting indefinitely for those threads to either succeed or fail with an Exception. See c3p0's docs for more.

Good luck!

Steve

I'm a bit of a newbie, really, but I see errors like this when I forget to start up my DB server (HSQLDB) before launching my hibernate application.

What DB server are you using? Are you sure it's running and accepting connections when these errors are generated?