> Some persisted entities are shared between threads, but not EntityManagers. This is the root of your problem. EntityManagers and Entities can't be shared across threads.
Thanks, Rick Section 7.2 -- JPA 2.0 Spec An entity manager must not be shared among multiple concurrently executing threads, as the entity manager and *persistence context are not required to be threadsafe*. Entity managers must only be accessed in a single-threaded manner. On Wed, Sep 28, 2011 at 5:38 AM, Tuomas Hynninen < tuomas.hynni...@surveypal.com> wrote: > Hi! > > I've been getting this error randomly: > > <openjpa-2.1.0-r422266:1071316 fatal internal error> > org.apache.openjpa.util.InternalException: Multiple concurrent threads > attempted to access a single broker. By default brokers are not thread safe; > if you require and/or intend a broker to be accessed by more than one > thread, set the openjpa.Multithreaded property to true to override the > default behavior. > at org.apache.openjpa.kernel.BrokerImpl.endOperation(BrokerImpl.java:1935) > ... > > The pattern in my web app is the "entity manager per request" pattern, > implemented like this: > > http://www.uta.fi/~th77842/PersistenceRequestListener.java > http://www.uta.fi/~th77842/PersistenceManager.java > > Basically, I force each request to have its own EntityManager. Some > persisted entities are shared between threads, but not EntityManagers. > > The problem only occurs when it's a Tomcat specific thread (e.g. > TP-Processor) using an EntityManager. I haven't had the problem using my own > agent threads or using the ThreadPoolExecutor > to process jobs. The problem has happened on inserts, selects or accessing > a field in a persisted entity. > > The servlet container I use is Tomcat 6. The database is PostgreSQL 8.1.4. > JPA related libraries I use: openjpa-2.1.0.jar, > geronimo-jpa_2.0_spec-1.1.jar, geronimo-jta_1.1_spec-1.1.1.jar. > > Persistence configuration: > > <properties> > <property name="openjpa.jdbc.DBDictionary" value="postgres"/> > <property name="openjpa.jdbc.DriverDataSource" value="dbcp"/> > <property name="openjpa.ConnectionProperties" > value="DriverClassName=org.postgresql.Driver, > Url=jdbc:postgresql://..., > MaxActive=100, > MaxWait=10000, > Username=test, > Password=test"/> > <property name="openjpa.ConnectionDriverName" > value="org.apache.commons.dbcp.BasicDataSource"/> > <property name="openjpa.Log" value="log4j"/> > <property name="openjpa.ConnectionFactoryProperties" > value="PrettyPrint=true, PrettyPrintLineLength=80, > PrintParameters=true"/> > <property name="openjpa.DataCache" value="false"/> > <property name="openjpa.InitializeEagerly" value="true"/> > <property name="openjpa.jdbc.SynchronizeMappings" > value="buildSchema"/> > </properties> > > For the life of me I can't figure out why it's still happening. I am > certain it's some subtle (or not so subtle) bug in my code or in the > configuration I've done. I can understand if OpenJPA throws the error on > persisted entities which are shared between threads, but it shouldn't > happen on simple inserts. > > Any help would be appreciated. Thanks! -- *Rick Curtis*
