Transaction isolation exception

 java.lang.RuntimeException: javax.persistence.PersistenceException: Cannot change transaction isolation level in the middle of a transaction.
	at com.excelfore.snap.SnapBase.initTables(SnapBase.java:626)
	at com.excelfore.snap.SnapStore.doService2(SnapStore.java:465)
	at com.excelfore.snap.SnapBase.doService(SnapBase.java:367)
	at com.excelfore.snap.SnapBase.doGet(SnapBase.java:401)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:622)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:292)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at com.excelfore.snap.filters.GzipInput.doFilter(GzipInput.java:46)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at com.excelfore.snap.filters.Hound.doFilter(Hound.java:75)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at com.excelfore.snap.filters.Encoding.doFilter(Encoding.java:105)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at com.excelfore.snap.filters.Opaque.doFilter(Opaque.java:49)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:240)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:207)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:212)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:106)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:141)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:79)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:88)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:509)
	at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1104)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:684)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1520)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1476)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
	at java.lang.Thread.run(Thread.java:748)
Caused by: javax.persistence.PersistenceException: Cannot change transaction isolation level in the middle of a transaction.
	at org.datanucleus.api.jpa.NucleusJPAHelper.getJPAExceptionForNucleusException(NucleusJPAHelper.java:316)
	at org.datanucleus.api.jpa.JPAQuery.getResultList(JPAQuery.java:220)
	at com.excelfore.snap.SnapBase.initTables(SnapBase.java:607)
	... 37 more
Caused by: org.postgresql.util.PSQLException: Cannot change transaction isolation level in the middle of a transaction.
	at org.postgresql.jdbc.PgConnection.setTransactionIsolation(PgConnection.java:887)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.postgresql.ds.PGPooledConnection$ConnectionHandler.invoke(PGPooledConnection.java:333)
	at com.sun.proxy.$Proxy72.setTransactionIsolation(Unknown Source)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:498)
	at org.apache.tomcat.jdbc.pool.ProxyConnection.invoke(ProxyConnection.java:126)
	at org.apache.tomcat.jdbc.pool.JdbcInterceptor.invoke(JdbcInterceptor.java:108)
	at org.apache.tomcat.jdbc.pool.DisposableConnectionFacade.invoke(DisposableConnectionFacade.java:81)
	at com.sun.proxy.$Proxy11.setTransactionIsolation(Unknown Source)
	at org.datanucleus.store.rdbms.ConnectionFactoryImpl$ManagedConnectionImpl.getConnection(ConnectionFactoryImpl.java:448)
	at org.datanucleus.store.rdbms.AbstractSchemaTransaction.getCurrentConnection(AbstractSchemaTransaction.java:86)
	at org.datanucleus.store.rdbms.RDBMSStoreManager$ClassAdder.performTablesValidation(RDBMSStoreManager.java:3452)
	at org.datanucleus.store.rdbms.RDBMSStoreManager$ClassAdder.run(RDBMSStoreManager.java:2974)
	at org.datanucleus.store.rdbms.AbstractSchemaTransaction.execute(AbstractSchemaTransaction.java:118)
	at org.datanucleus.store.rdbms.RDBMSStoreManager.manageClasses(RDBMSStoreManager.java:1677)
	at org.datanucleus.store.rdbms.RDBMSStoreManager.getDatastoreClass(RDBMSStoreManager.java:648)
	at org.datanucleus.store.rdbms.query.RDBMSQueryUtils.getStatementForCandidates(RDBMSQueryUtils.java:430)
	at org.datanucleus.store.rdbms.query.JPQLQuery.compileQueryFull(JPQLQuery.java:802)
	at org.datanucleus.store.rdbms.query.JPQLQuery.compileInternal(JPQLQuery.java:316)
	at org.datanucleus.store.query.Query.executeQuery(Query.java:1928)
	at org.datanucleus.store.query.Query.executeWithMap(Query.java:1874)
	at org.datanucleus.api.jpa.JPAQuery.getResultList(JPAQuery.java:204)
	... 38 more