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From "Michael Gentry" <blackn...@gmail.com>
Subject Re: commitChanges() doesn't imply commit in db ?
Date Tue, 03 Apr 2007 17:16:05 GMT
FWIW in my case, deployed stack is:

Java 1.4, Tomcat 5.0, Cayenne 1.2, Sybase driver (jconn2.jar -- but I've
seen lots of different file sizes for this around here, so who knows what
version), and Cayenne is managing the connection pools (no J2EE "goodness"
or JNDI through Tomcat).

For us, it's always been after the application has been running a week or
more.  It is a low-volume utility application, but has threads which poll
the DBs at least once/hour looking for new updates.

One thing I haven't tried doing, but could be interesting, is seeing how
deeply the application is affected.  It accesses 5 different Sybase DBs
(identical schemas and polls all of them).  In the past, when we noticed a
problem with it doing an insert, I'd just restart it.  Next time it happens,
I should change DataContexts to one of the other DBs and see if it has the
same problem, too.  Unfortunately, it isn't repeatable for me.  There have
been times it took over a month for the problem to appear.

/dev/mrg


On 4/3/07, Andrus Adamchik <andrus@objectstyle.org> wrote:
>
> While I've never seen hung transactions in my apps, there were other
> users [1] who are seeing some strangeness. So let's try to figure out
> what's going on.
>
> 1. What DataSource are you using - Cayenne-provided or some other
> (e.g. container-provided). Either should work of course, but this
> information should help in debugging.
>
> 2. Are you using container-managed transactions? If you are, you have
> to check "container-managed transactions" [2], and ensure that
> whatever transaction mechanism is used (i.e. explicit J2EE
> UserTransactions), you commit them explicitly.
>
> These are the starting points to debug the transactions.
>
> Andrus
>
> [1] http://objectstyle.org/cayenne/lists/cayenne-user/2007/04/0019.html
> [2] http://cayenne.apache.org/doc/understanding-transactions.html
>
>
> On Apr 3, 2007, at 12:03 PM, jerome moliere wrote:
>
> > Thanks for your reply michael,
> > i was wondering about my code ....
> >
> > 2007/4/3, Michael Gentry <blacknext@gmail.com>:
> >>
> >> Hmm, this is interesting.  I've noticed transactions uncommitted
> >> against
> >> our
> >> Sybase DB, too.  I've usually attributed this to a problem with
> >> the Sybase
> >> connection getting stale or something else going awry inside the
> >> database
> >> because our process (and the connection to the DB) is long-running
> >> (a web
> >> application that is hardly ever restarted) and the problem only
> >> occurs
> >> after
> >> it has been running for a while and a restart of the application
> >> clears
> >> the
> >> problem up (fetching data from the DB still works in our case,
> >> though).  It
> >> sounds like yours isn't that long-term of a connection, though.
> >> Now I'm
> >> wondering if there is a problem with the Sybase driver or
> >> something inside
> >> Cayenne.  Is there any chance you can make a repeatable test
> >> case?  Our
> >> experience with the issue has been very intermittent and not
> >> reproducible
> >> and Cayenne was always logging the proper SQL.
> >
> >
> > in fact it's very simple, i'll try to make a small drawing of my test:
> >
> >
> >  App1 = thread querying a table all 10 seconds
> >               after the first query -> send a message on a tibco queue
> >
> > App 2 = wait for notification on the tibco queue
> > get the item (id passed into the message) then update this record (one
> > field)
> > send a message for notifying about field update via tibco
> > App 3 = wait for the notification and displays the new value (once
> > again
> > query on db)
> >
> > SO at this point app1 runs but with bad results after the first query
> > App2 seems to work but does'nt commit
> > App3 is never notified...
> >
> > I'll try to package a small test case using openjms ?
> > It's very disappointing because Sybase is the database choice from my
> > customers (like in many financial companies)...
> >
> > Cheers
> > jerome
> >
> > Thanks,
> >>
> >> /dev/mrg
> >>
> >>
> >> On 4/3/07, jerome moliere <jerome.moliere@gmail.com> wrote:
> >> >
> >> > Hi all,
> >> >
> >> > I'm doing a proof of concepts of several tricky usage from orm ,
> >> one of
> >> > the
> >> > 2 implementations is Cayenne...
> >> > I've one scenario where 3 process (stand-alone Java
> >> applications) use
> >> the
> >> > same table on db and communicate via Tibco rendez vous...
> >> > It works fine with Hibernate, but I 've got several problems with
> >> > cayenne...
> >> > latest one is while updating one object in one of these
> >> applications,
> >> > invoking commitChanges() on my context, nothing happens..
> >> > the query logger shows me a trans begin, the right update query
> >> but this
> >> > transaction is never committed
> >> > strange isn't it ?
> >> > This is the output (excerpt )from my process trying to update one
> >> entity:
> >> >
> >> > [java] INFO  QueryLogger - +++ Connecting: SUCCESS.
> >> >      [java] INFO  QueryLogger - --- transaction started.
> >> >      [java] INFO  DbAdapterFactoryChain - DB name: Adaptive Server
> >> > Enterprise
> >> >      [java] INFO  QueryLogger - Detected and installed adapter:
> >> > org.apache.cayenne.dba.sybase.SybaseAdapter
> >> >      [java] INFO  QueryLogger - SELECT t0.AggregationCurrency,
> >> > t0.AllowFixing, t0.FixingAskSpread, t0.FixingBidSpread,
> >> t0.IsIslamic,
> >> > t0.IsLocal, t0.OISRoundingConv, t0.Currencies_Id FROM
> >> dbo.CurrenciesLocTt0
> >> > WHERE t0.Currencies_Id = ? [bind: 105] - prepared in 37 ms.
> >> >      [java] INFO  QueryLogger - === returned 1 row. - took 71 ms.
> >> >      [java] INFO  QueryLogger - +++ transaction committed.
> >> >      [java] INFO  CayenneCurrencyDAOImpl - before update
> >> isIslamicChar
> >> set
> >> > to = Y
> >> >      [java] INFO  CayenneCurrencyDAOImpl - after update this
> >> filed is
> >> now
> >> > set to = N
> >> >      [java] INFO  QueryLogger - --- will run 1 query.
> >> >      [java] INFO  QueryLogger - --- transaction started.
> >> >      [java] INFO  QueryLogger - UPDATE dbo.CurrenciesLocT SET
> >> IsIslamic
> >> =
> >> > ?
> >> > WHERE Currencies_Id = ?
> >> >      [java] INFO  QueryLogger - [bind: 'N', 105]
> >> >
> >> >
> >> > druid shows me that the tranaction is never committed, like one
> >> of the
> >> > other
> >> > applications lauching as a daemon a query on this table (does
> >> not show
> >> any
> >> > update because there are not..)
> >> >
> >> > Any clue ?
> >> > cheers
> >> > jerome
> >> >
> >> > --
> >> > Jerome Moliere - Mentor/J
> >> > http://romjethoughts.blogspot.com/
> >> > auteur Eyrolles
> >> >
> >>
> >
> >
> >
> > --
> > Jerome Moliere - Mentor/J
> > http://romjethoughts.blogspot.com/
> > auteur Eyrolles
>
>

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