java - Hibernate 和 Apache Tomcat 的问题

Question

我用 Hibernate JPA 的实现在我的项目中，使用 Apache Tomcat 作为服务器和 PostgreSQL作为数据库。有一段时间，我遇到了一个错误，并不是每次都出现。拿到后，如果我重新启动服务器，一般一切都会顺利。波纹管是堆栈跟踪:

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

问题:我不明白为什么我会收到这个错误。如果您认为您可以提出问题所在，请尽管提出。

(注意，如果您需要更多详细信息，请告诉我)。

Answer 1

PostgreSQL 日志应该会说明更多，但您可能已经用完了

连接。查询 max-connections在 postgresql.conf 中。 Link to doc for 9.1

内存不足，oom-killer 会终止您的连接。 Link to doc for 9.1和一个 article on PostgreSQL memory management and linux