并发请求失败 - “会话已关闭！”答案

【问题标题】：Concurrent request fail - "Session is closed!"并发请求失败 - “会话已关闭！”
【发布时间】：2017-03-29 23:27:53
【问题描述】：

我不知道我下面的代码有什么问题。如果我从浏览器点击我的请求，它工作正常。但是当我发出并发请求时，它会说 Session is closed! 失败。我同时或同时访问以下两个网址（异步调用）。

http://localhost:8080/getEmployee
http://localhost:8080/getDepartment

Controller.java

@RequestMapping(value = "/getEmployees", method = RequestMethod.POST)
 public @ResponseBody List<Employee> getEmployee() {

        List<Employee> empList = null;
        empList = services.getEmployee();
        return empList;
    }

 @RequestMapping(value = "/getDepartments", method = RequestMethod.GET)
 public @ResponseBody List<Department> getDepartment() {

        List<Department> deptList = null;
        deptList = services.getDepartment();
        return deptList;
    }

两个模型类

Table 1 (Employee)
@Entity
@Table(name = "employee")
public class Employee implements java.io.Serializable {

    private static final long serialVersionUID = 2650114334774359089L;

    @Id
    @Column(name = "id", unique = true, nullable = false, length = 100)
    private String id;

    @Column(name = "name", unique = true, nullable = false, length = 50)
    private String name;

// getter setter

//第二个模型类

Table 2 (Department)
@Entity
@Table(name = "department")
public class Department implements java.io.Serializable {

    private static final long serialVersionUID = 2650114334774359089L;

    @Id
    @Column(name = "id", unique = true, nullable = false, length = 100)
    private String id;

    @Column(name = "dept_name", unique = true, nullable = false, length = 50)
    private String dept_name;

    // getter setter

DAOImpl

@Autowired
    SessionFactory sessionFactory;

    Session session = null;
    Transaction tx = null;

    static final Logger LOGGER = Logger.getLogger(DataDaoImpl.class);
    public List<Employee> getEmployee() throws Exception {
        List<Employee> result = null;
        session = sessionFactory.openSession();
        String hql = "from Employee";
        Query lQuery = session.createQuery(hql);
        result = lQuery.list();
        tx = session.getTransaction();
        session.beginTransaction();
        tx.commit();
        return result;
    }

    public List<Department> getDepartment() throws Exception {
        List<Department> result = null;
        session = sessionFactory.openSession();
        String hql = "from Department";
        Query lQuery = session.createQuery(hql);
        result = lQuery.list();
        tx = session.getTransaction();
        session.beginTransaction();
        tx.commit();
        return result;
    }

服务实现

@Override
    public List<Employee> getEmployee() throws Exception {
        return dataDao.getEmployee();
    }

    @Override
    public List<Department> getDepartment() throws Exception {
        return dataDao.getDepartment();
    }

spring-config.xml

<bean id="dataSource"
        class="org.springframework.jdbc.datasource.DriverManagerDataSource">

        <property name="driverClassName" value="com.mysql.jdbc.Driver" /> 
        <property name="url" value="jdbc:mysql://localhost:3306/mydb" />
        <property name="username" value="root" />
        <property name="password" value="password"/>
    </bean>

    <bean id="sessionFactory"
        class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="annotatedClasses">
            <list>
                <value>com.srdh.model.Employee</value>
                <value>com.srdh.model.Department</value>

            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
                <prop key="hibernate.show_sql">${hibernate.show_sql}</prop>
                <prop key="hibernate.hbm2ddl.auto">update</prop>
            </props>
        </property>
    </bean>

    <bean id="txManager"
        class="org.springframework.orm.hibernate4.HibernateTransactionManager">
        <property name="sessionFactory" ref="sessionFactory" />
    </bean>

    <bean id="persistenceExceptionTranslationPostProcessor"
        class="org.springframework.dao.annotation.PersistenceExceptionTranslationPostProcessor" />

    <bean id="dataDao" class="com.test.dao.DaoImpl"></bean>
    <bean id="dataServices" class="com.test.service.ServicesImpl"></bean>

谁能帮助我在我的代码中做错了什么。我只有一个 DAO 可以同时访问部门和员工表。我必须从各个表中获取记录并显示在输出中。在并发请求中它失败了。

错误堆栈跟踪

org.hibernate.HibernateException: createQuery is not valid without active transaction
    at org.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:352)
    at com.sun.proxy.$Proxy139.createQuery(Unknown Source)
    at com.srdh.dao.DataDaoImpl.getDepartment(DataDaoImpl.java:49)
    at com.srdh.service.DataServicesImpl.getDepartment(DataServicesImpl.java:26)
    at com.srdh.controller.MainController.getDepartment(MainController.java:44)
    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.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:218)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:958)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:452)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1087)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:318)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
org.hibernate.SessionException: Session is closed!
    at org.hibernate.internal.AbstractSessionImpl.errorIfClosed(AbstractSessionImpl.java:133)
    at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1433)
    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.hibernate.context.internal.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:356)
    at com.sun.proxy.$Proxy139.beginTransaction(Unknown Source)
    at com.srdh.dao.DataDaoImpl.Employee(DataDaoImpl.java:126)
    at com.srdh.service.DataServicesImpl.Employee(DataServicesImpl.java:71)
    at com.srdh.controller.MainController.Employee(MainController.java:73)
    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.springframework.web.method.support.InvocableHandlerMethod.invoke(InvocableHandlerMethod.java:215)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:132)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:104)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandleMethod(RequestMappingHandlerAdapter.java:749)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:689)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:83)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:938)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961)
    at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:624)
    at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:218)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:505)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:958)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:452)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1087)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:745)
org.hibernate.TransactionException: nested transactions not supported
    at org.hibernate.engine.transaction.spi.AbstractTransactionImpl.begin(AbstractTransactionImpl.java:154)
    at org.hibernate.internal.SessionImpl.beginTransaction(SessionImpl.java:1435)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

【问题讨论】：

“说会话关闭失败！” - 我敢打赌它说的更多，例如它提供堆栈跟踪等。作为一般规则：每当您询问某些异常/错误时，请尽可能多地提供有关异常/错误本身的信息（例如堆栈跟踪和堆栈跟踪中提到的代码的相关部分）。
@Thomas我添加了我在问题中遇到的错误

标签： java spring hibernate session concurrency

【解决方案1】：

错误堆栈跟踪显示createQuery is not valid without active transaction，从中我们可以看到没有活动的事务，换句话说，没有打开的事务，这是因为您在打开事务之前创建并执行了query。

所以你的大错误是你在打开任何事务之前查询数据库。

你需要移动：

tx = session.getTransaction();
session.beginTransaction();

在您创建和执行查询的行之前。

并且您在每个请求中都使用了新的Session，您应该使用sessionFactory.getCurrentSession() 而不是sessionFactory.openSession()。

所以你需要像这样更新你的代码：

 public List<Employee> getEmployee() throws Exception {
    List<Employee> result = null;
    Session session = sessionFactory.getCurrentSession();
    Transaction tx = session.getTransaction();
    session.beginTransaction();
    String hql = "from Employee";
    Query lQuery = session.createQuery(hql);
    result = lQuery.list();
    tx.commit();
    return result;
}


public List<Department> getDepartment() throws Exception {
    List<Department> result = null;
    Session session = sessionFactory.getCurrentSession();
    Transaction tx = session.getTransaction();
    session.beginTransaction();
    String hql = "from Department";
    Query lQuery = session.createQuery(hql);
    result = lQuery.list();
    tx.commit();
    return result;
}

这应该可以解决您的问题。

注意：

正如@SergeBallesta 报告和指出的那样，您不应该在您的DAO 中使用session 和tx 作为实例变量，您最好在您的方法中使用它们作为本地变量，就像我上面的代码一样。

【讨论】：

@user4324324 看看我的编辑，我用你的错误堆栈跟踪更新了我的答案。
@SergeBallesta 这应该报告给 OP，我只是给他一个关于他的错误的解决方案。
@SergeBallesta 我明白你的意思。不，我并没有说它是安全的

【解决方案2】：

您的 DAOImpl 看起来很可疑。

Spring bean 通常是单例的。您正在运行的程序中只有一个 Spring bean 实例。您没有发布完整的代码，但看起来您的类 DAOImpl 具有会话和事务的成员变量。

如果多个线程同时使用同一个单例DAOImpl对象，改变成员变量，那么它们就会互相干扰。处理一个请求的线程将看到另一个处理另一个请求的线程的会话和事务。

不要将状态（成员变量）放在单例 Spring bean 中。 session 和 tx 不应该也不需要是 DAOImpl 类中的成员变量。在 getEmployee 和 getDepartment 方法中将它们设为局部变量。

更好的是使用Spring Data JPA 而不是实现您自己的DAO 对象。这样更容易，您不必自己直接处理较低级别的细节，例如获取会话和事务。

【讨论】：