spring – 未使用jpaFlowExecutionListener关闭数据库连接

2024年2月2日 216次阅读

我正在使用
Spring Web Flow来构建应用程序.我正在使用Flow Managed Persistence Context,因此实体管理器在我的流程执行期间“保持打开”,我可以访问延迟加载的属性(类似于Spring MVC的OpenEntityManagerInViewFilter或OpenSessionInViewFilter).当我使用它时,每次提交表单时,活动数据库连接的数量都会增加,如果我不使用FMPC,则打开连接的数量没有问题).

我正在使用以下设置.

事务管理：

@Bean
@Autowired
public JpaTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
    return new JpaTransactionManager(entityManagerFactory);
}

数据源：

@Bean
public DataSource dataSource() {
    final BasicDataSource dataSource = new BasicDataSource();
    dataSource.setDriverClassName(environment.getRequiredProperty(PROPERTY_DATABASE_DRIVER));
    dataSource.setUrl(environment.getRequiredProperty(PROPERTY_DATABASE_URL));
    dataSource.setUsername(environment.getProperty(PROPERTY_DATABASE_USERNAME, ""));
    dataSource.setPassword(environment.getProperty(PROPERTY_DATABASE_PASSWORD, ""));
    return dataSource;
}

EntityManagerFactory的：

@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
    final LocalContainerEntityManagerFactoryBean factoryBean = new LocalContainerEntityManagerFactoryBean();
    factoryBean.setDataSource(dataSource());
    factoryBean.setPackagesToScan(environment.getRequiredProperty(PROPERTY_ENTITYMANAGER_PACKAGES_TO_SCAN));

    final JpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter() {
        {
            setDatabase(Database.valueOf(environment.getRequiredProperty(PROPERTY_DATABASE_TYPE)));
            setDatabasePlatform(environment.getRequiredProperty(PROPERTY_HIBERNATE_DIALECT));
        }
    };
    factoryBean.setJpaVendorAdapter(vendorAdapter);

    final Properties jpaProperties = new Properties();
    jpaProperties.put(PROPERTY_HIBERNATE_FORMAT_SQL, environment.getRequiredProperty(PROPERTY_HIBERNATE_FORMAT_SQL));
    jpaProperties.put(PROPERTY_HIBERNATE_NAMING_STRATEGY, environment.getRequiredProperty(PROPERTY_HIBERNATE_NAMING_STRATEGY));
    jpaProperties.put(PROPERTY_HIBERNATE_SHOW_SQL, environment.getRequiredProperty(PROPERTY_HIBERNATE_SHOW_SQL));
    jpaProperties.put(PROPERTY_HIBERNATE_HB2DDL_SQL, environment.getRequiredProperty(PROPERTY_HIBERNATE_HB2DDL_SQL));

    factoryBean.setJpaProperties(jpaProperties);

    return factoryBean;
}

JpaFlowExecutionListener：

@Bean
@Autowired
public JpaFlowExecutionListener jpaFlowExecutionListener(EntityManagerFactory entityManagerFactory, JpaTransactionManager transactionManager) {
    return new JpaFlowExecutionListener(entityManagerFactory, transactionManager);
}

默认情况下,BasicDataSource的maxActive设置为8,当我达到8个活动连接时,页面就会挂起.为什么请求完成后连接没有关闭？我使用了Chrome调试工具(网络窗格)来确保没有运行AJAX请求或任何东西,我的页面提交(HTTP POST)触发301重定向,然后给我一个新的HTTP GET并导致状态200,所以一切都好.

当从一个页面转到下一个页面时,会调用一个服务层,但是从我的bean中可以看到,我正在使用JpaTransactionManager,SWF文档说明如下：

  • Note: All data access except for the final commit will, by default, be non-transactional. However, a flow may call into a transactional service layer to fetch objects during the conversation in the context of a read-only system transaction if the underlying JPA Transaction Manager supports this. Spring’s JPA TransactionManager does support this when working with a Hibernate JPA provider, for example. In that case, Spring will handle setting the FlushMode to MANUAL to ensure any in-progress changes to managed persistent entities are not flushed, while reads of new objects occur transactionally.

为了完整起见,我的spring-web-flow配置：

<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:webflow="http://www.springframework.org/schema/webflow-config"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="
           http://www.springframework.org/schema/beans
           http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
           http://www.springframework.org/schema/webflow-config
           http://www.springframework.org/schema/webflow-config/spring-webflow-config.xsd">

    <!-- Flow executor, repsonsible for creating and executing flows -->
    <webflow:flow-executor id="flowExecutor" flow-registry="flowRegistry">
        <webflow:flow-execution-listeners>
            <webflow:listener ref="jpaFlowExecutionListener"/>
        </webflow:flow-execution-listeners>
    </webflow:flow-executor>

    <!-- Flow registry, responsible for loading all flows so executor can execute them -->
    <webflow:flow-registry id="flowRegistry" base-path="/WEB-INF/webflow/flows" flow-builder-services="flowBuilderServices">
        <webflow:flow-location-pattern value="/**/*-flow.xml"/>
    </webflow:flow-registry>

    <!-- Flow builder services -->
    <webflow:flow-builder-services id="flowBuilderServices" view-factory-creator="mvcViewFactoryCreator"/>

    <!-- MvcViewFactoryCreator -->
    <bean id="mvcViewFactoryCreator" class="org.springframework.webflow.mvc.builder.MvcViewFactoryCreator">
        <property name="viewResolvers">
            <list>
                <ref bean="viewResolver"/>
            </list>
        </property>
    </bean>

    <!-- Flow handler adapter, responsible for answering request for a flow -->
    <bean class="org.springframework.webflow.mvc.servlet.FlowHandlerAdapter">
        <property name="flowExecutor" ref="flowExecutor"/>
    </bean>

    <!-- Flow handler mapping, lets Spring MVCs DispatcherServlet know to send flow request to SWF -->
    <bean class="org.springframework.webflow.mvc.servlet.FlowHandlerMapping">
        <property name="flowRegistry" ref="flowRegistry"/>
        <property name="order" value="0"/>
        <property name="interceptors">
            <list>
                <ref bean="localeChangeInterceptor" />
            </list>
        </property>
    </bean>
</beans>

我的流程有< persistence-context />在顶部定义.

我有以下结束状态(重新启动流),即使我调用它并且URL参数更改为e2s1,活动连接的数量也不会重置：

<end-state id="restart" commit="true" view="redirect:/main"/>

最佳答案 所以似乎hibernate.connection.release_mode的默认hibernate属性是on_close.考虑到EntityManager在整个流程期间保持打开状态,它永远不会关闭,并且为流中的每个请求从池中提取新连接.

将属性更改为after_transaction可以解决此问题.但是,在获取延迟加载的集合的情况下,它仍然不起作用,每个惰性属性将从池中获取新连接.为了解决这个问题,我用以下方法扩展了JpaFlowExecutionListener：

public class AvoidLeakJpaFlowExecutionListener extends JpaFlowExecutionListener {

    public AvoidLeakJpaFlowExecutionListener(EntityManagerFactory entityManagerFactory, PlatformTransactionManager transactionManager) {
        super(entityManagerFactory, transactionManager);
    }

    @Override
    public void paused(RequestContext context) {
        super.paused(context);
        EntityManager entityManager = (EntityManager) context.getFlowScope().get(PERSISTENCE_CONTEXT_ATTRIBUTE);
        if (entityManager != null && entityManager instanceof HibernateEntityManager) {
            HibernateEntityManager hibernateEntityManager = (HibernateEntityManager) entityManager;
            hibernateEntityManager.getSession().disconnect();
        }
    }
}

这种方法解决了延迟加载的集合问题,但是在使用WebFlow的持久化上下文完成加载延迟初始化实体时仍会泄漏连接,并且在转换到未配置的子流期间执行此加载.如in this bug report所述(我也找到了这个解决方案).

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