Spring Boot中使用Hibernate SessionFactory进行连接泄漏

Question

spring.jpa.properties.hibernate.current_session_context_class=org.springframework.orm.hibernate4.SpringSessionContext

在configuration类中：

@Bean
public HibernateJpaSessionFactoryBean sessionFactory() {
    return new HibernateJpaSessionFactoryBean();
}

在@services中：

@Autowired
private SessionFactory sessionFactory;

这个效果不错。但我的问题是，在每一个请求之后，我会得到越来越多的空闲PostgreSQL进程，并且在许多请求之后，我最终会得到以下结果：

Caused by: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
...
Caused by: org.postgresql.util.PSQLException: FATAL: remaining connection slots are reserved for non-replication superuser connections
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2455) ~[postgresql-9.4.1212.jre7.jar:9.4.1212.jre7]
...
[ERROR] [16.05.17 20:19:39]               DirectJDKLog.java:181  Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception
org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction; 
nested exception is javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:431) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
...
Caused by: javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1692) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
...
Caused by: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
...
Caused by: org.postgresql.util.PSQLException: FATAL: remaining connection slots are reserved for non-replication superuser connections
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2455) ~[postgresql-9.4.1212.jre7.jar:9.4.1212.jre7]
...
[ERROR] [16.05.17 20:19:39]               DirectJDKLog.java:181  Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception
org.springframework.transaction.CannotCreateTransactionException: Could not open JPA EntityManager for transaction;
nested exception is javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.springframework.orm.jpa.JpaTransactionManager.doBegin(JpaTransactionManager.java:431) ~[spring-orm-4.3.8.RELEASE.jar:4.3.8.RELEASE]
...
Caused by: javax.persistence.PersistenceException: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1692) ~[hibernate-entitymanager-5.0.12.Final.jar:5.0.12.Final]
...
Caused by: org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection
at org.hibernate.exception.internal.StandardSQLExceptionConverter.convert(StandardSQLExceptionConverter.java:47) ~[hibernate-core-5.0.12.Final.jar:5.0.12.Final]
...
Caused by: org.postgresql.util.PSQLException: FATAL: remaining connection slots are reserved for non-replication superuser connections
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2455) ~[postgresql-9.4.1212.jre7.jar:9.4.1212.jre7]
...
[ WARN] [16.05.17 20:19:40]         SqlExceptionHelper.java:127  SQL Error: 0, SQLState: 53300
[ERROR] [16.05.17 20:19:40]         SqlExceptionHelper.java:129  FATAL: remaining connection slots are reserved for non-replication superuser connections
[ERROR] [16.05.17 20:19:40]               DirectJDKLog.java:181  Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; 
nested exception is org.hibernate.exception.GenericJDBCException: Unable to acquire JDBC Connection] with root cause
org.postgresql.util.PSQLException: FATAL: remaining connection slots are reserved for non-replication superuser connections
at org.postgresql.core.v3.QueryExecutorImpl.receiveErrorResponse(QueryExecutorImpl.java:2455) ~[postgresql-9.4.1212.jre7.jar:9.4.1212.jre7]

这些明显泄漏的原因是什么？

为了完整起见，这里的一些示例在@service中使用：

@Transactional(readOnly = true)
@Cacheable(value = "countries", key = "#root.methodName")
public List<Country> getCountries() {
    final StatelessSession session = sessionFactory.openStatelessSession();
    final Query query = session.createQuery("from Country order by id");
    final List<Country> result = query.list();
    session.close();
    return result;
}

@Transactional(readOnly = true)
public long countTimeZones() {
    final StatelessSession session = sessionFactory.openStatelessSession();
    final Long result = (Long) session.createQuery("select count(o) from TimeZone o").uniqueResult();
    session.close();
    return result;
}

@Transactional(readOnly = true)
public List<Map<String, Object>> getPhotoAlbums() {
    final StatelessSession session = sessionFactory.openStatelessSession();
    final SQLQuery query = session.createSQLQuery("select "
            + "cast(m.id as varchar), "
            + "m.name "
            // etc
            + "from media_album m "
            + "where m.account = :account "
            + "and ... "
            + "order by ...");
    query.setParameter("account", uuidOfAccount);
    query.setResultTransformer(AliasToEntityMapResultTransformer.INSTANCE);
    final List<Map<String, Object>> result = query.list();
    session.close();
    return result;
}

Answer 1

我可以通过如下方式更改配置来“解决”泄漏（但不确定所有这些步骤都是必需的）：

应用程序.属性：

spring.jpa.properties.hibernate.current_session_context_class=
org.springframework.orm.hibernate5.SpringSessionContext

配置类：

添加@enableAutoConfiguration，以及：

@Bean
public HibernateJpaSessionFactoryBean sessionFactory(EntityManagerFactory emf) {
    HibernateJpaSessionFactoryBean factory = new HibernateJpaSessionFactoryBean();
    factory.setEntityManagerFactory(emf);
    return factory;
}