Eclipse link jpa problem

Question

With two users simultaneously using my simple app, I'm getting exception:

Error Code: 0
Call: SELECT ID, NAME, IMAGE FROM GameObjectTable ORDER BY ID ASC
Query: ReadAllQuery(referenceClass=GameObject sql="SELECT ID, NAME, IMAGE FROM GameObjectTable ORDER BY ID ASC")

Caused by: org.postgresql.util.PSQLException: There was In/Out error while sending to server
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:283)
at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:479)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:367)
at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:271)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeSelect(DatabaseAccessor.java:891)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:601)
... 116 more
Caused by: java.io.IOException: Stream closed
at sun.nio.cs.StreamEncoder.ensureOpen(StreamEncoder.java:26)
at sun.nio.cs.StreamEncoder.flush(StreamEncoder.java:121)
at java.io.OutputStreamWriter.flush(OutputStreamWriter.java:212)
at org.postgresql.core.PGStream.flush(PGStream.java:507)
at org.postgresql.core.v3.QueryExecutorImpl.sendSync(QueryExecutorImpl.java:1107)
at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:256)
... 121 more

Method cousing error is:

@Repository
public class GameObjectDao{
  @PersistenceContext(type = PersistenceContextType.EXTENDED)
  protected EntityManager entityManager;
  @Transactional
  public List<String> getGameObjectNames() {
    return getEntityManager().createQuery("select g.name from GameObject as g").getResultList();
 ...
}

}

Spring transaction manager:

<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
    <property name="entityManagerFactory" ref="entityManagerFactory"/>
    <property name="dataSource" ref="dataSource"/>
</bean>
<tx:annotation-driven />

What is wrong?

//EDIT

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
    <property name="dataSource" ref="dataSource"/>
    <property name="jpaVendorAdapter">
        <bean class="org.springframework.orm.jpa.vendor.EclipseLinkJpaVendorAdapter">
            <property name="showSql" value="false"/>
        </bean>
    </property>

    <property name="loadTimeWeaver">
        <bean class="org.springframework.instrument.classloading.InstrumentationLoadTimeWeaver"/>
    </property>
    <property name="jpaDialect">
        <bean class="org.springframework.orm.jpa.vendor.EclipseLinkJpaDialect "/>
    </property>

</bean>

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
    <property name="driverClassName" value="org.postgresql.Driver"/>
    <property name="url" value="${db.url}"/>
    <property name="username" value="${db.username}"/>
    <property name="password" value="${db.password}"/>
</bean>

In mysql error is different:

 Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at org.apache.wicket.session.DefaultPageFactory.createPage(DefaultPageFactory.java:192)
... 69 more
    Caused by: java.lang.NullPointerException
at com.mysql.jdbc.PreparedStatement.fillSendPacket(PreparedStatement.java:1646)
at com.mysql.jdbc.PreparedStatement.fillSendPacket(PreparedStatement.java:1622)
at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1332)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeSelect(DatabaseAccessor.java:891)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.basicExecuteCall(DatabaseAccessor.java:601)
at org.eclipse.persistence.internal.databaseaccess.DatabaseAccessor.executeCall(DatabaseAccessor.java:529)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeCall(AbstractSession.java:914)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:205)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeCall(DatasourceCallQueryMechanism.java:191)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.executeSelectCall(DatasourceCallQueryMechanism.java:262)
at org.eclipse.persistence.internal.queries.DatasourceCallQueryMechanism.selectAllRows(DatasourceCallQueryMechanism.java:618)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRowsFromTable(ExpressionQueryMechanism.java:2537)
at org.eclipse.persistence.internal.queries.ExpressionQueryMechanism.selectAllRows(ExpressionQueryMechanism.java:2496)
at org.eclipse.persistence.queries.ReadAllQuery.executeObjectLevelReadQuery(ReadAllQuery.java:455)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeDatabaseQuery(ObjectLevelReadQuery.java:997)
at org.eclipse.persistence.queries.DatabaseQuery.execute(DatabaseQuery.java:675)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.execute(ObjectLevelReadQuery.java:958)
at org.eclipse.persistence.queries.ReadAllQuery.execute(ReadAllQuery.java:432)
at org.eclipse.persistence.queries.ObjectLevelReadQuery.executeInUnitOfWork(ObjectLevelReadQuery.java:1021)
at org.eclipse.persistence.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2863)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1225)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1207)
at org.eclipse.persistence.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:1181)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.executeReadQuery(EJBQueryImpl.java:453)
at org.eclipse.persistence.internal.jpa.EJBQueryImpl.getResultList(EJBQueryImpl.java:669)

Answer 1

If the first exception translates to (as I'm guessing):

org.postgresql.util.PSQLException: An I/O error occured while sending to the backend. 

Then it is very likely not an EclipseLink issue but a PostgreSQL issue.

Set the following in postgresql.conf on the server and reload:

log_statement=all
log_min_error_statement=ERROR
log_min_messages=ERROR
log_connections=on
log_disconnections=on

Then check the server logs and update your question with any suspicious message (and the lines surrounding it).

Answer 2

It seems that the database connection is being closed by the first request, and the second request retrieves the closed connection from the pool and fails.

What does your datasource definition look like?