Tomcat负载均衡序列化异常PersistenceExceptionTranslationInterceptor：延迟初始化异常答案

【问题标题】：Tomcat loadbalancing serialize exception PersistenceExceptionTranslationInterceptor : lazy initialization exceptionTomcat负载均衡序列化异常PersistenceExceptionTranslationInterceptor：延迟初始化异常
【发布时间】：2011-11-10 11:03:01
【问题描述】：

我必须将两个 tomcat 服务器（tcat01 和 tcat02）放在负载平衡架构中。

我使用的是 tomcat 6.x，我在 tomcat tcat01 上像这样编辑了 conf/server.xml：

<Engine name="Catalina" defaultHost="localhost" jvmRoute="tcat01">
     <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" channelSendOptions="6"/>
      ....

在 tcat02 上 conf/server.xml 是这样的：

 <Engine name="Catalina" defaultHost="localhost" jvmRoute="tcat02">
     <Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" channelSendOptions="6"/>
      ....

我启动了tcat01，然后是tcat02，il catalina.out 看来tcat01 和tcat02 通信很好。

然后我用互联网导航器连接到 webapp，然后每次我在 webapp 中做某事（我的意思是当我导航时）都会出现这个异常：

  Nov 24, 2011 12:00:13 AM org.apache.catalina.core.ContainerBase backgroundProcess
WARNING: Exception processing manager org.apache.catalina.ha.session.DeltaManager@278c4835 background process
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.mycompany.myproject.model.authentification.Authority.groups, no session or session was closed
    at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:383)
    at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:375)
    at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:368)
    at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:111)
    at org.hibernate.collection.PersistentSet.toString(PersistentSet.java:332)
    at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)
    at java.io.ObjectOutputStream.writeObject0(Unknown Source)
    at java.io.ObjectOutputStream.defaultWriteFields(Unknown Source)
    at java.io.ObjectOutputStream.writeSerialData(Unknown Source)
    at java.io.ObjectOutputStream.writeOrdinaryObject(Unknown Source)

这里是不能sezialized类的代码（即堆栈跟踪中提到的java bean）：

import static javax.persistence.GenerationType.IDENTITY;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.PrePersist;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;
import javax.validation.constraints.Pattern;
import javax.validation.constraints.Size;

@Entity
@Table(name = "authority", uniqueConstraints = @UniqueConstraint(columnNames = "name"))
public class Authority implements java.io.Serializable {

/**
 * 
 */
private static final long serialVersionUID = -7436593455923433675L;

//SYSTEM ROLE CONSTANT
public static final String MANAGER_SYSTEM_ROLE = "ROLE_MANAGER";
public static final String CLIENT_SYSTEM_ROLE = "ROLE_CLIENT";
public static final String PEDAGO_ADMIN_SYSTEM_ROLE = "ROLE_PEDAGO_ADMIN";

private Integer id;
@Size(min=1)
@Pattern(regexp="^ROLE[_a-zA-Z]+$", message="{authority.name.pattern.error}")
private String name;
@Size(max=65535)
private String description;


private Boolean isSystem;

private Set<Group> groups = new HashSet<Group>(0);

public Authority() {
    this.isSystem = false;
}

public Authority(String name) {
    this.name = name;
    this.isSystem = false;
}

public Authority(String name, String description, Set<Group> groups) {
    this.name = name;
    this.description = description;
    this.groups = groups;
    this.isSystem = false;
}

@Id
@GeneratedValue(strategy = IDENTITY)
@Column(name = "id", unique = true, nullable = false)
public Integer getId() {
    return this.id;
}

public void setId(Integer id) {
    this.id = id;
}

@Column(name = "name", unique = true, nullable = false, length = 45)
public String getName() {
    return this.name;
}

public void setName(String name) {
    this.name = name;
}

@Column(name = "description")
public String getDescription() {
    return this.description;
}

public void setDescription(String description) {
    this.description = description;
}

public void setIsSystem(Boolean isSystem) {
    this.isSystem = isSystem;
}

@Column(name = "system")
public Boolean getIsSystem() {
    return isSystem;
}

@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "group_authorities", joinColumns = { @JoinColumn(name = "authority_id", nullable = false, updatable = true) }, inverseJoinColumns = { @JoinColumn(name = "group_id", nullable = false, updatable = true) })
public Set<Group> getGroups() {
    return this.groups;
}

public void setGroups(Set<Group> groups) {
    this.groups = groups;
}

@PrePersist
protected void updateSystemField() {
    if(isSystem == null)
        isSystem = false;
}
}

这里是 java bean Group 的代码（因为我们在 Groups 集合上有一个延迟初始化异常）：

import static javax.persistence.GenerationType.IDENTITY;

import java.util.HashSet;
import java.util.Set;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.JoinTable;
import javax.persistence.ManyToMany;
import javax.persistence.PrePersist;
import javax.persistence.Table;
import javax.persistence.UniqueConstraint;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;


@Entity
@Table(name = "groups", uniqueConstraints = @UniqueConstraint(columnNames = "name"))
public class Group implements java.io.Serializable {

/**
 * 
 */
private static final long serialVersionUID = 7380068327050752558L;

private Integer id;
@NotNull
@Size(min=1)
private String name;
private String description;

private Boolean isSystem;

private Set<Authority> authorities = new HashSet<Authority>(0);
private Set<User> users = new HashSet<User>(0);

public Group() {
    this.isSystem = false;
}

public Group(String name) {
    this.name = name;
    this.isSystem = false;
}

public Group(String name, String description, Set<Authority> authorities, Set<User> users) {
    this.name = name;
    this.description = description;
    this.isSystem = false;
    this.authorities = authorities;
    this.users = users;
}

@Id
@GeneratedValue(strategy = IDENTITY)
@Column(name = "id", unique = true, nullable = false)
public Integer getId() {
    return this.id;
}

public void setId(Integer id) {
    this.id = id;
}

@Column(name = "name", unique = true, nullable = false, length = 45)
public String getName() {
    return this.name;
}

public void setName(String name) {
    this.name = name;
}

@Column(name = "description")
public String getDescription() {
    return this.description;
}

public void setDescription(String description) {
    this.description = description;
}

public void setIsSystem(Boolean isSystem) {
    this.isSystem = isSystem;
}

@Column(name = "system")
public Boolean getIsSystem() {
    return isSystem;
}

@ManyToMany(fetch = FetchType.EAGER)
@JoinTable(name = "group_authorities", joinColumns = { @JoinColumn(name = "group_id", nullable = false, updatable = true) }, inverseJoinColumns = { @JoinColumn(name = "authority_id", nullable = false, updatable = true) })
public Set<Authority> getAuthorities() {
    return this.authorities;
}

public void setAuthorities(Set<Authority> authorities) {
    this.authorities = authorities;
}

@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "group_users", joinColumns = { @JoinColumn(name = "group_id", nullable = false, updatable = true) }, inverseJoinColumns = { @JoinColumn(name = "user_id", nullable = false, updatable = true) })
public Set<User> getUsers() {
    return this.users;
}

public void setUsers(Set<User> users) {
    this.users = users;
}

public void addAuthority(Authority authority) {
    if(authorities == null)
        authorities = new HashSet<Authority>(0);
    authorities.add(authority);
}

public boolean removeAuthority(Authority authority) {
    return authorities == null || authorities.remove(authority);
}

public void addUser(User user) {
    if(users == null)
        users = new HashSet<User>(0);
    users.add(user);
}

public boolean removeUser(User user) {
    return users == null || users.remove(user);
}

@PrePersist
protected void updateSystemField() {
    if(isSystem == null)
        isSystem = false;
}
}

感谢您的帮助

【问题讨论】：

看起来tomcat正在尝试序列化会话并且会话中有无法序列化的属性，我建议您查看正在添加到会话的对象并查看它们是否可以序列化.
你说得对，我在谷歌上找到了 JVM 的选项“-Dsun.io.serialization.extendedDebugInfo=true”。当我添加这个选项时，我看到了哪些对象不能被序列化。我不知道我是否可以在 stackoverflow 中更改我的问题的详细信息，如果我不能，我将创建另一个问题。关于哪些对象不能序列化：带有惰性集合的java bean，其实我有一个惰性异常！我的懒集合不能序列化，不知道怎么解决这个问题。
能不能把不能序列化的对象的代码贴出来，只要对象实现了java.io.Serializable接口就可以序列化了。
好的，我做到了，我编辑了我的原始帖子，以便提供更好的堆栈跟踪（因为我激活了 JVM 参数 sun.io.serialization.extendedDebugInfo=true）
我认为@Chris 是对的，如果您不想更改映射，请在加载授权后查看 Hibernate.initialize 进行初始化。 javalobby.org/java/forums/t62077.html

标签： java tomcat serialization load-balancing session-replication

【解决方案1】：

您得到了惰性实例化异常，因为您将权限组映射为惰性。到会话被复制时，您已处于活动会话之外，因此无法对其进行补水。为了解决这个问题，您有几个选择：

更改您的映射，以便快速获取关联
更改您的 DAO 以进入该集合（或使用 hibernate.initialize）以强制在会话关闭之前发生延迟加载
从会话中分离对象，然后在对象被放入会话之前将组显式设置为 null 以替换那里的休眠代理。

对于这种特殊情况，选项 1 或 2 可能是最干净的。

【讨论】：