Joe Luo created ARIES-1083:
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Summary: Create either a synchronised entity manager or a proxy
which creates an entity manager for each request
Key: ARIES-1083
URL: https://issues.apache.org/jira/browse/ARIES-1083
Project: Aries
Issue Type: Improvement
Components: JPA
Affects Versions: jpa-container-context-1.0.1
Reporter: Joe Luo
When using Apache Aries (container managed Transactions, JTA) with Hibernate
for persistence, if we start multiple threads to read from the database without
transactions (Transaction Annotation is ommited), we get the following
stacktrace:
org.hibernate.AssertionFailure: possible non-threadsafe access to the session
at
org.hibernate.engine.internal.TwoPhaseLoad.initializeEntity(TwoPhaseLoad.java:130)
at
org.hibernate.loader.Loader.initializeEntitiesAndCollections(Loader.java:1103)
at org.hibernate.loader.Loader.processResultSet(Loader.java:960)
at org.hibernate.loader.Loader.doQuery(Loader.java:910)
at
org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:341)
at org.hibernate.loader.Loader.doList(Loader.java:2516)
at org.hibernate.loader.Loader.doList(Loader.java:2502)
at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2332)
at org.hibernate.loader.Loader.list(Loader.java:2327)
at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:490)
at
org.hibernate.hql.internal.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:355)
at
org.hibernate.engine.query.spi.HQLQueryPlan.performList(HQLQueryPlan.java:195)
at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1247)
at org.hibernate.internal.QueryImpl.list(QueryImpl.java:101)
The reason we got this exception in a non-transacted mode is that we inject
EntityManager in our implementation and use it for different requests from
multiple threads. Unfortunately, the EntityManager is not thread safe and we
have to refactor the code to inject EntityManagerFactory instead since
EntityManagerFactory is thread safe and then create EntityManagers in each
method programmatically.
>From Aries stand point, we should be able to improve it in order to ease the
>pain by creating a synchronized entity manager, or a proxy which creates
>entity managers for each request. And the proxy would probably do the
>following:
1. create EntityManager;
2. perform request;
3. close EntityManager;
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