Issue with Hibernate and Apache Tomcat
===

I use `Hibernate` implementation of `JPA` in my project, with *Apache Tomcat* as server and `Pstgres` as database. From some time, I got an error, that isn't present every time. After I got it, if I restart the server, in general every thing goes well. Bellow is the stack trace:

<pre><code>
javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: could not execute query
	at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1389)
	at org.hibernate.ejb.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1317)
	at org.hibernate.ejb.QueryImpl.getSingleResult(QueryImpl.java:307)
	at com.netnfork.business.authentication.UserChecking.isValidUser(UserChecking.java:105)
	at com.netnfork.authentication.AuthLogin.doPost(AuthLogin.java:55)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:169)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:472)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:927)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
	at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:200)
	at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:307)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1110)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:603)
	at java.lang.Thread.run(Thread.java:679)
Caused by: org.hibernate.exception.GenericJDBCException: could not execute query
	at org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:140)
	at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:128)
	at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
	at org.hibernate.loader.Loader.doList(Loader.java:2545)
	at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2276)
	at org.hibernate.loader.Loader.list(Loader.java:2271)
	at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:316)
	at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1842)
	at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:165)
	at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:157)
	at org.hibernate.ejb.QueryImpl.getSingleResult(QueryImpl.java:274)
	... 20 more
Caused by: org.postgresql.util.PSQLException: FATAL: terminating connection due to administrator command
	at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2103)
	at org.postgresql.core.v3.QueryExecutorImpl.processResults(QueryExecutorImpl.java:1836)
	at org.postgresql.core.v3.QueryExecutorImpl.execute(QueryExecutorImpl.java:257)
	at org.postgresql.jdbc2.AbstractJdbc2Statement.execute(AbstractJdbc2Statement.java:512)
	at org.postgresql.jdbc2.AbstractJdbc2Statement.executeWithFlags(AbstractJdbc2Statement.java:388)
	at org.postgresql.jdbc2.AbstractJdbc2Statement.executeQuery(AbstractJdbc2Statement.java:273)
	at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208)
	at org.hibernate.loader.Loader.getResultSet(Loader.java:1953)
	at org.hibernate.loader.Loader.doQuery(Loader.java:802)
	at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:274)
	at org.hibernate.loader.Loader.doList(Loader.java:2542)
	... 27 more
</code></pre>

**Question:** I can't understand why I get this error. If you think you can suggest what's the issue, just do it please. 

(N.B. If you need more details just tell me).