NonUniqueObjectException only in debug mode

ripos · **Posted:** Tue Apr 22, 2008 1:34 pm

After a call saveOfUpdate(project) sometimes NonUniqueObjectException is thrown. project object have id==0 and is not attached to session.

I've read plenty of topics in the internet, that claims about get()/load() in the incorrect places.
But strangest thing for my problem is that it depends on debugging mode.

When I step into next method and then step over its lines then error does not appear.

Code:

   private void addNewProjectToPerson(Person dbPerson) {
      project.setPerson(dbPerson);
      hibernateSessionFactory.getCurrentSession().saveOrUpdate(project); // here is the place where exception will be thrown
      dbPerson.getProjects().add(project);
   }

But is I step over this method, then error appears.

I do not understand how debugging mode could be connected with Hibernate exceptions. I believe, that I did not make the same mistake as everybody who usually gets NonUniqueObjectException.

Error scenario is reproducible on the same http calls from browser on the same database data.

Where should I look for the cause of the problem?
Should I try to create something smaller, that shows the same error?
Should I debug Hibernate throws its sources?
Should I try other version of Hibernate?

What else could you suggest me?

I've spend more than two days isolating this error scenario and trying different things to solve it. Looks like I still have this error.

I will be grateful for any help or yours suggestions.

Hibernate version:
3.2.6 + 3.3.1 Hibernate Annotations

Full stack trace of any exception that occurs:
ERROR 22.04.2008 17:13:05,124 [http-8080-Processor23] [[default]] Servlet.service() for servlet default threw exception
org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [my.company.entities.Project#26]
at org.hibernate.engine.StatefulPersistenceContext.checkUniqueness(StatefulPersistenceContext.java:590)
at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:303)
at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:181)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:107)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:187)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:172)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:94)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:70)
at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:507)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:499)
at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:495)
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:585)
at org.hibernate.context.ThreadLocalSessionContext$TransactionProtectionWrapper.invoke(ThreadLocalSessionContext.java:301)
at $Proxy20.saveOrUpdate(Unknown Source)

Name and version of the database you are using:
MySQL 5

sanne.grinovero · **Posted:** Tue Apr 22, 2008 5:12 pm

is it possible you have some unusual code in toString()?
Some debuggers implicitly call it to show you the current state in GUI,
but could affect you entity; eg. you could concatenate some uninitialized field, which gets initialized because of the debug mode.

ripos · **Posted:** Thu Apr 24, 2008 10:05 am

Thank you for your answer s.grinovero.
I deleted all toString() methods from all entity classes, nothing changed.

I have verified, that Hibernate version is not the cause of the problem.

Just as a reference Project class and Person class.

Code:

package my.company.entities;

import com.opensymphony.xwork2.conversion.annotations.Conversion;
import com.opensymphony.xwork2.conversion.annotations.TypeConversion;

import javax.persistence.*;
import java.util.Date;

@Entity
@Conversion
public class Project implements SearchablePart {

   @Id @GeneratedValue private long id;

   private String name;
   @Temporal(value = TemporalType.DATE)
   private Date startDate;
   @Temporal(value = TemporalType.DATE)
   private Date endDate;
   private String site;
   @Lob private String comments;
   @ManyToOne private Person person;
   private String role;

   @Transient
   public Searchable getSearchableOwner() {
      return person;
   }

   public Date getStartDate() { return startDate; }

   @TypeConversion(converter = "my.company.web.util.StringToDateTypeConverter")
   public void setStartDate(Date startDate) { this.startDate = startDate; }

   public Date getEndDate() { return endDate; }

   @TypeConversion(converter = "my.company.web.util.StringToDateTypeConverter")
   public void setEndDate(Date endDate) { this.endDate = endDate; }

   // all getter/setter without @ were omitted
}

Code:

package my.company.entities;

import com.opensymphony.xwork2.conversion.annotations.Conversion;
import com.opensymphony.xwork2.conversion.annotations.TypeConversion;
import my.company.search.SearchDataType;

import javax.persistence.*;
import java.io.Serializable;
import java.util.*;

@Entity
@Conversion
public class Person extends Loginable implements Serializable, Searchable {

   /** Says how many invites can the new Zubberki user give out by default */
   public static final int DEFAULT_INVITES_PER_PERSON = 20;

   @Id @GeneratedValue private long id;

   @Column(columnDefinition = "VARBINARY(255)")
   private byte[] passwordHash;

   @Temporal(value = TemporalType.DATE)

   // many irrelevant fields were omitted

   private int invitesLeft = DEFAULT_INVITES_PER_PERSON;

   private boolean priviledged = false;

   @OneToOne private ImageLink userPic;
   @ManyToMany private Set<Category> categories;
   @OneToMany(mappedBy = "person")
   private Set<Project> projects = new HashSet<Project>();
   @OneToMany(mappedBy = "person")
   private Set<Education> educations = new HashSet<Education>();
   @ManyToMany(cascade = { CascadeType.ALL })
   private Set<Communicator> favoriteCommunicators = new HashSet<Communicator>();
   @OneToMany(mappedBy = "person")
   private Set<Organization> organizations = new HashSet<Organization>();
   @OneToMany(mappedBy = "owner")
   private List<Document> documents = new ArrayList<Document>();

   @Transient
   public SearchDataType getSearchDataType() {
      return SearchDataType.PERSON;
   }

   @Transient
   public Project getProject(long projectId) {
      if(projects == null) return null;
      for(Project project : projects) {
         if(project.getId() == projectId) {
            return project;
         }
      }
      return null;
   }

   @Transient
   public Organization getOrganization(long orgRoleId) {
      if(organizations == null) return null;
      for(Organization organization : organizations) {
         if(organization.getId() == orgRoleId) {
            return organization;
         }
      }
      return null;
   }

   @Transient
   public Education getEducation(long educationId) {
      if(educations == null) return null;
      for(Education education : educations) {
         if(education.getId() == educationId) {
            return education;
         }
      }
      return null;
   }

   // many getters/setters without @ were omitted   

   public Date getBirthDate() { return birthDate; }

   @TypeConversion(converter = "my.company.web.util.StringToDateTypeConverter")
   public void setBirthDate(Date birthDate) { this.birthDate = birthDate; }

}

ripos · **Posted:** Thu Apr 24, 2008 6:21 pm

Finally I found a root cause of a problem.

Code:

public class Project implements SearchablePart { 
   @Transient 
   public Searchable getSearchableOwner() { 
      return person; 
   } 

Code:

session.sync(project) {
   call onPostInsert(PostInsertEvent event) 
      1) Gets person through project.getSearchableOwner()
      2) Iterate through all projects of a person, which instantiates all projects
   call checkUniqueness(EntityKey key, Object object)
      1) Check for uniqueness of a project deeply inside .sync
      2) But project were already created, so .sync() thinks, that this is another one project (I suppose) and throws exception.
}

I do not understand why debugging mode changes this behavior, cause I did not set any breakpoints inside .sync(project) call, only outside.

I will try to find some workaround to make this work.