I think the issue isn't threading so much as it is a nested transaction
issue. I am pretty sure that nested transactions are not committed.
Therefore I think Steve's problem is that the outermost transaction is
not finished and hasn't finished when the thread is created. There is
no easy way around this because so many service methods in openmrs are
transactional. That is why I have argued against transactional
annotations on service methods. The only way I could ever get around
this was using a hack with stateless sessions.
Tammy Dugan
Quoting Wyclif Luyima <[email protected]>:
@McKee, this is why i said i'm not sure if the way you are coding up the
threads is correct, starting thread A and call flushSession() on it and
then starting thread B afterwards doesn't guarantee that all lines of code
in thread B will executed after all lines in thread A unless you have
explicitly called threadA.join() in thread B.
Wyclif.
On Wed, Jan 25, 2012 at 8:12 AM, McKee, Steven Jay <[email protected]>wrote:
I?m calling flush session before the second thread is even created. Is
the flush session call on a thread of its own? Why else would the data not
be there if I explicitly tell it to flush? How would you go about making
the second thread wait on the first to successfully flush?****
** **
Thanks,****
Steve****
** **
*From:* [email protected] [mailto:[email protected]] *On Behalf Of *Wyclif
Luyima
*Sent:* Tuesday, January 24, 2012 10:16 PM
*To:* [email protected]
*Subject:* Re: [OPENMRS-DEV] Hibernate Sessions Issue****
** **
I'm not sure how you are coding this out, but of course what i said can
fail if the second thread tries to accesses the created patientState
before the first has actually flushed its session . Basically ensure, you
can make the second thread wait on the first to guarantee that the session
is flushed.****
** **
Wyclif****
On Tue, Jan 24, 2012 at 9:26 PM, McKee, Steven Jay <[email protected]>
wrote:****
I was able to give flushing session one a try, but it did not solve the
problem. I?m still running into conditions where the spawned thread
intermittently does not know about the PatientState object created in
session one.****
****
Steve****
****
*From:* McKee, Steven Jay
*Sent:* Friday, December 30, 2011 10:24 AM
*To:* '[email protected]'
*Subject:* RE: [OPENMRS-DEV] Hibernate Sessions Issue****
****
Thanks, Wyclif! I?ll give this a try.****
****
Steve****
****
*From:* [email protected] [mailto:[email protected]] *On Behalf Of *Wyclif
Luyima
*Sent:* Thursday, December 29, 2011 4:45 PM
*To:* [email protected]
*Subject:* Re: [OPENMRS-DEV] Hibernate Sessions Issue****
****
The hibernate session is associated to the same thread as that of the
authenticated user's context, so if any updates/inserts in one thread are
not yet persisted to the DB until the session is flushed, implying the
changes won't be visible to other threads. You need to ensure that the
first session is flushed, you can manually call Context.flushSession() on
the first thread before starting the second thread.****
****
Wyclif****
On Thu, Dec 29, 2011 at 3:56 PM, Burke Mamlin <[email protected]>
wrote:****
Are you creating the PatientState within an application session in the
first session ? calling openSession & closeSession on either end? When you
saw then session one "inserts a new PatientSate", that means that you are
creating the new object through the API, right?****
****
FWIW, while we're subject to Hibernate unpredictability until our API is
rewritten, having changes to objects sometimes persisted before asking the
API to save them is a smaller problem than calling create or save on an
object and not having those changes reliably persisted. If the latter is
happening (as your issue suggests), then we need to fix it.****
****
-Burke****
****
On Thu, Dec 29, 2011 at 11:30 AM, McKee, Steven Jay <[email protected]>
wrote:****
I?m currently running OpenMRS 1.7, and I?m seeing an intermittent issue
across Hibernate sessions in our CHICA code:****
****
1. Session one inserts a new PatientState (CHICA specific
table/object).****
2. A new thread is created to do some processing on the
PatientState. The patient state ID is passed to the thread.****
3. Session two is created in the new thread and tries to get a
PatientState object based on the patient state ID.****
4. The PatientState object is coming back null.****
****
It seems as though session one has not committed the new patient state and
session two is trying to access it. What is the best Hibernate mechanism
to use to ensure the patient state is committed to the database before
session two tries to access it? Keep in mind the PatientState object is
being accessed outside the DAO layer.****
****
Thanks,****
Steve****
****
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