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From Mike Kienenberger <>
Subject Re: java.sql.SQLException: Can't obtain connection. Request timed out.
Date Fri, 12 Jun 2015 15:09:37 GMT
Thanks for the pointer to jstack.  Looking through the output now, but
the problem doesn't persist.   I've only had it happen twice in 3 or 4

I guess I need to dump a full all-thread stacktrace like jstack when
the problem occurs to see what is going on.

I'm also looking through the poolmanager source to see if there's any
additional logging I could turn on, but I'm not seeing anything
cayenne-related executing at the moment.

And, interestingly enough, I only have 8 "PoolManagerCleanup" threads,
and not the 9 that I expected.  Maybe they are create-on-demand and
one of my runtimes hasn't needed it yet?

On Fri, Jun 12, 2015 at 10:56 AM, Andrus Adamchik
<> wrote:
> So there's a leak somewhere. Do you see any hanging threads with jstack, or maybe some
unclosed ResultIterators?
> Andrus
>> On Jun 12, 2015, at 5:51 PM, Mike Kienenberger <> wrote:
>> ....And upping my connection pool size from 1 to 3 didn't help as I
>> got the error again today, but this time with all 3 in use.
>> Caused by: java.sql.SQLException: Can't obtain connection. Request
>> timed out. Total used connections: 3
>> On Thu, Jun 11, 2015 at 11:41 AM, Mike Kienenberger <> wrote:
>>> So what I had when I originally deployed would have been three pools
>>> of one connection each?   That's fine.  And that explains why it
>>> worked without problems.
>>> So when I increased to 3 connections, I actually have 9 now, three in
>>> each of the three pools which I definitely do not want.
>>> So apparently I only hit this problem in a single runtime's connection
>>> pool, and not in all of them.   That should make it easier to track
>>> down what caused it.   Thanks.
>>> On Thu, Jun 11, 2015 at 11:32 AM, Andrus Adamchik
>>> <> wrote:
>>>>> My guess is that all three runtimes share the same pool
>>>> Actually no. If you have 3 runtimes, and let Cayenne instantiate its pool
(as the stack trace implies) instead of using say container JNDI DataSource, you should have
3 instances of the pool. You can try confirming the number of PoolManager instances with VisualVM
or jmap.
>>>> Andrus
>>>>> On Jun 11, 2015, at 6:18 PM, Mike Kienenberger <>
>>>>> So I finally put my old Cayenne 1.x-upgraded to 3.x app into production.
>>>>> A couple of hours later, I got this error [1].   Note that my app
>>>>> synchronizes requests so only one thread should ever be running
>>>>> Cayenne requests at a time.
>>>>> My app has run for years with only a single connection.   My 3.x app
>>>>> ran in development for a year before it was deployed to production.
>>>>> Is this a fluke?   I did raise my connection pool to 3 the next day,
>>>>> but I don't want to arbitrarily assign a higher number and think I've
>>>>> magically solved the problem.
>>>>> Does having three active server runtimes affect this?   Before, my
>>>>> query qualifiers were all handled inside the main runtime, but now I
>>>>> have three separate runtimes configured.   My guess is that all three
>>>>> runtimes share the same pool, so this is probably not the cause.   And
>>>>> since the problem happened a couple hours later and the three runtimes
>>>>> were being used well before that without an error, I'd say experience
>>>>> bears this out.
>>>>> [1]
>>>>> Caused by: java.sql.SQLException: Can't obtain connection. Request
>>>>> timed out. Total used connections: 1
>>>>>       at org.apache.cayenne.conn.PoolManager.uncheckPooledConnection(
>>>>>       at org.apache.cayenne.conn.PoolManager.getConnection(
>>>>>       at org.apache.cayenne.conn.PoolManager.getConnection(
>>>>>       at org.apache.cayenne.access.DataNode$TransactionDataSource.getConnection(
>>>>>       at org.apache.cayenne.access.DataNode.performQueries(

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