[
https://issues.apache.org/jira/browse/OPENJPA-2507?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14016377#comment-14016377
]
David Bilge edited comment on OPENJPA-2507 at 6/3/14 10:50 AM:
---------------------------------------------------------------
I experienced this very bug and created a demo project (see attached
{{openjpa-exception-demo.zip}}) - if that helps. Just execute
{{LoadTest#parallelTest}} and invariably one of the exceptions in
{{exceptions.txt}} will be thrown. One of those is the {{EmptyStackException}}.
It is easy to reproduce this without Spring Data by using this alternative
implementation for the {{DemoRepository}} interface from the demo project:
{code:java}
@Component
public class ManualDemoRepository implements DemoRepository {
@Autowired
EntityManager entityManager;
CriteriaQuery<DemoEntity> criteriaQuery;
@PostConstruct
public void initQuery() {
CriteriaBuilder criteriaBuilder =
entityManager.getCriteriaBuilder();
criteriaQuery = criteriaBuilder.createQuery(DemoEntity.class);
Root<DemoEntity> demoRoot =
criteriaQuery.from(DemoEntity.class);
criteriaQuery.select(demoRoot).where(criteriaBuilder.equal(demoRoot.get(DemoEntity_.demoNumber),
42));
}
@Override
public DemoEntity findByDemoNumber(int demoNumber) {
return
entityManager.createQuery(criteriaQuery).getSingleResult();
}
}
{code}
was (Author: viadavid):
I experienced this very bug and created a demo project - if that helps. Just
execute {{LoadTest#parallelTest}} and invariably one of the exceptions in
{{exceptions.txt}} will be thrown. One of those is the {{EmptyStackException}}.
It is easy to reproduce this without Spring Data by using this alternative
implementation for the {{DemoRepository}} interface from the demo project:
{code:java}
@Component
public class ManualDemoRepository implements DemoRepository {
@Autowired
EntityManager entityManager;
CriteriaQuery<DemoEntity> criteriaQuery;
@PostConstruct
public void initQuery() {
CriteriaBuilder criteriaBuilder =
entityManager.getCriteriaBuilder();
criteriaQuery = criteriaBuilder.createQuery(DemoEntity.class);
Root<DemoEntity> demoRoot =
criteriaQuery.from(DemoEntity.class);
criteriaQuery.select(demoRoot).where(criteriaBuilder.equal(demoRoot.get(DemoEntity_.demoNumber),
42));
}
@Override
public DemoEntity findByDemoNumber(int demoNumber) {
return
entityManager.createQuery(criteriaQuery).getSingleResult();
}
}
{code}
> Weird EmptyStackException in CriteriaQueryImpl
> ----------------------------------------------
>
> Key: OPENJPA-2507
> URL: https://issues.apache.org/jira/browse/OPENJPA-2507
> Project: OpenJPA
> Issue Type: Bug
> Components: criteria
> Affects Versions: 2.2.0, 2.3.0
> Environment: openjpa 2.2.0 & 2.3.0, spring-data-jpa up to 1.4.2
> Reporter: Ioannis Alexandrakis
> Priority: Minor
> Labels: criteria_api, openjpa
> Attachments: exceptions.txt, openjpa-exception-demo.zip
>
>
> Using spring-data-jpa with openjpa, I sometimes encounter a strange error
> (not all the times, but under heavy load it makes its appearance, sparsely
> though):
> ....
> Caused by: java.util.EmptyStackException
> at java.util.Stack.peek(Stack.java:<arbitrary line>)
> at
> org.apache.openjpa.persistence.criteria.CriteriaQueryImpl.ctx(CriteriaQueryImpl.java:<arbitrary
> line>
> ....
> I do not know which behaviour triggers it, however I think it would be an
> improvement to change (I did not know where exactly to file it, because it is
> both an improvement and a bug in my opinion), in
> org.apache.openjpa.persistence.criteria.CriteriaQueryImpl, method: Context
> ctx(), this:
> return _contexts == null || _contexts.isEmpty() ? null : _contexts.peek();
> to something like this:
> try {
> return _contexts == null || _contexts.isEmpty() ? null :
> _contexts.peek();
> } catch (EmptyStackException e) {
> return null;
> }
> , in order to prevent a case where multiple threads modify the "_contexts"
> between the evaluation of the inline "if".
> I am not able to reproduce it all the time, thus I can't create a useful
> test, neither have I created a patch due to the simplicity of the 'fix'.
> However I believe it is a harmless fix which could be considered a minor
> improvement.
--
This message was sent by Atlassian JIRA
(v6.2#6252)
