What causes a NotSerializableException in Tomcat 7?

java tomcat7 notserializableexception
coder picture coder · Aug 1, 2011 · Viewed 75.6k times · Source

My DAO implementation is throwing a not serializable exception on server start up with Tomcat7. Any idea what causes this? None of my other DAOs are doing this.

Here's the class:

package com.project.dao;

import java.util.List;

import org.hibernate.SessionFactory;
import org.springframework.orm.hibernate3.HibernateTemplate;

import com.project.model.User;

public class UserDAOImpl implements UserDAO {
    private HibernateTemplate hibernateTemplate;

    public void setSessionFactory(SessionFactory sessionFactory) {
        this.hibernateTemplate = new HibernateTemplate(sessionFactory);
    }

    @Override
    public void saveUser(User user) {
        hibernateTemplate.saveOrUpdate(user);
    }

    @Override
    @SuppressWarnings("unchecked")
    public List<User> listUser() {
        return hibernateTemplate.find("from User");
    }

    @Override
    @SuppressWarnings("unchecked")
    public User getUserByID(long userID) {
        List<User> users= hibernateTemplate.find("from User where id = '" + userID + "'");
        return users.size() > 0 ? users.get(0) : null;
    }
}

Here's my config:

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:mvc="http://www.springframework.org/schema/mvc"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">
    <bean id="myDataSource" 
    class="org.apache.tomcat.dbcp.dbcp.BasicDataSource">
      <property name="driverClassName">
        <value>com.mysql.jdbc.Driver</value>
      </property>
      <property name="url">
        <value>jdbc:mysql://localhost/context</value>
      </property>
      <property name="username">
        <value>someUser</value>
      </property>
      <property name="password">
        <value>somePassword</value>
      </property>
      <!-- Disable the second-level cache  -->
        <!-- Echo all executed SQL to stdout -->
    </bean>
    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
        <property name="dataSource" ref="myDataSource" /> 
        <property name="annotatedClasses">
            <list>
                <value>com.project.model.User</value>
            </list>
        </property> 
        <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
            <prop key="hibernate.show_sql">true</prop>
            <prop key="hibernate.show_sql">true</prop>
        </props>
        </property>
    </bean>
    <bean id="myUserDAO" class="com.project.dao.UserDAOImpl">
        <property name="sessionFactory" ref="sessionFactory"/>
    </bean> 
</beans>

Here's my stack:

SEVERE: IOException while loading persisted sessions: java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException: com.news.dao.UserDAOImpl
java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException: com.project.dao.UserDAOImpl

at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1332)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
at org.apache.catalina.session.StandardSession.readObject(StandardSession.java:1600)
at org.apache.catalina.session.StandardSession.readObjectData(StandardSession.java:1073)
at org.apache.catalina.session.StandardManager.doLoad(StandardManager.java:284)
at org.apache.catalina.session.StandardManager.load(StandardManager.java:204)
at org.apache.catalina.session.StandardManager.startInternal(StandardManager.java:470)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5241)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:774)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:291)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:727)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.startup.Catalina.start(Catalina.java:620)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:303)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:431)

Caused by: java.io.NotSerializableException: com.project.dao.UserDAOImpl
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1164)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:330)
at org.apache.catalina.session.StandardSession.writeObject(StandardSession.java:1676)
at org.apache.catalina.session.StandardSession.writeObjectData(StandardSession.java:1090)
at org.apache.catalina.session.StandardManager.doUnload(StandardManager.java:411)
at org.apache.catalina.session.StandardManager.unload(StandardManager.java:353)
at org.apache.catalina.session.StandardManager.stopInternal(StandardManager.java:497)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.StandardContext$4.run(StandardContext.java:5464)
at java.lang.Thread.run(Thread.java:662)
at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5481)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.ContainerBase.stopInternal(ContainerBase.java:1072)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.ContainerBase.stopInternal(ContainerBase.java:1072)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.StandardService.stopInternal(StandardService.java:502)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.StandardServer.stopInternal(StandardServer.java:748)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.startup.Catalina.stop(Catalina.java:693)
at org.apache.catalina.startup.Catalina.start(Catalina.java:654)
... 6 more
Jul 31, 2011 9:27:21 PM org.apache.catalina.session.StandardManager startInternal

SEVERE: Exception loading sessions from persistent storage
java.io.WriteAbortedException: writing aborted; java.io.NotSerializableException: com.project.dao.UserDAOImpl
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1332)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1946)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1870)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
at org.apache.catalina.session.StandardSession.readObject(StandardSession.java:1600)
at org.apache.catalina.session.StandardSession.readObjectData(StandardSession.java:1073)
at org.apache.catalina.session.StandardManager.doLoad(StandardManager.java:284)
at org.apache.catalina.session.StandardManager.load(StandardManager.java:204)
at org.apache.catalina.session.StandardManager.startInternal(StandardManager.java:470)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5241)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
at org.apache.catalina.core.StandardHost.startInternal(StandardHost.java:774)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.ContainerBase.startInternal(ContainerBase.java:1033)
at org.apache.catalina.core.StandardEngine.startInternal(StandardEngine.java:291)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardService.startInternal(StandardService.java:443)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.core.StandardServer.startInternal(StandardServer.java:727)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:145)
at org.apache.catalina.startup.Catalina.start(Catalina.java:620)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:303)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:431)

Caused by: java.io.NotSerializableException: com.project.dao.UserDAOImpl
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1164)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1518)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1483)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:330)
at org.apache.catalina.session.StandardSession.writeObject(StandardSession.java:1676)
at org.apache.catalina.session.StandardSession.writeObjectData(StandardSession.java:1090)
at org.apache.catalina.session.StandardManager.doUnload(StandardManager.java:411)
at org.apache.catalina.session.StandardManager.unload(StandardManager.java:353)
at org.apache.catalina.session.StandardManager.stopInternal(StandardManager.java:497)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.StandardContext$4.run(StandardContext.java:5464)
at java.lang.Thread.run(Thread.java:662)
at org.apache.catalina.core.StandardContext.stopInternal(StandardContext.java:5481)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.ContainerBase.stopInternal(ContainerBase.java:1072)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.ContainerBase.stopInternal(ContainerBase.java:1072)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.StandardService.stopInternal(StandardService.java:502)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.core.StandardServer.stopInternal(StandardServer.java:748)
at org.apache.catalina.util.LifecycleBase.stop(LifecycleBase.java:225)
at org.apache.catalina.startup.Catalina.stop(Catalina.java:693)
at org.apache.catalina.startup.Catalina.start(Catalina.java:654)
... 6 more

Answer

pap picture pap · Aug 1, 2011

It is happening because somewhere in your code, you are storing a UserDAO in the session (or you are storing an object that has a reference to a UserDAO). Tomcat tries to serialize the full object graph of all active sessions when you shut it down, and then it tries to restore them when you start it back up. The crux of this is that Tomcat uses "normal" java object serialization, which requires all objects to be Serializable.

How to remedy:

  1. Don't store non-serializable objects in the users session (generally a good practice).
  2. Make your UserDAO serializable. Probably involves implementing the Serializable interface and marking your hibernateTemplate as transient as i don't think that HibernateTemplate is, in itself, serializable. You may have to add some code that re-initialize the hibernateTemplate on deserialization if you really want it to work.
  3. Don't have Tomcat serializing sessions (add <Manager pathname="" /> to the context.xml, either in your own app or in the global tomcat context.xml in the conf/ directory, inside the <Context> element. This might be the best course of action for you, unless you really need sessions to be persisted across restarts.

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