"Cached Item Was Locked" causing Select Statement in Hibernate

Question

I am having trouble with getting some caching to work with hibernate exactly the way I would like. I created some example code to replicate this problem I am having.

I have one object that contains instances of itself. For instance, a Part that is made up of more Parts.

I really need to minimize the select statements that Hibernate is using when an updated object comes in. After going through the logs, I see this log output that is causing a SELECT statement:

Cached item was locked: com.cache.dataobject.Part.parts#1

What can I change in my annotation mappings, xml files, caching provider, or logic to keep the cached item from being locked? I would really like to get rid of that select statement.

I included the Entity, DataObject, code I am testing with, and log output.

Hibernate version: 3.4

EHCache Version: 1.2.3 (Included with Hibernate Download)

Part DataObject:

package com.cache.dataobject;

import java.io.Serializable;
import java.lang.String;
import java.util.List;

import javax.persistence.*;

import org.hibernate.annotations.Cache;
import org.hibernate.annotations.CacheConcurrencyStrategy;

import static javax.persistence.CascadeType.ALL;

/**
 * Entity implementation class for Entity: Part
 * 
 */
@Entity
@Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
public class Part implements Serializable {

    private int id;
    private String name;
    private static final long serialVersionUID = 1L;
    private Part mainPart;
    private List<Part> parts;

    public Part() {
        super();
    }

    @Id
    public int getId() {
        return this.id;
    }

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

    @Column(name = "PART_NAME")
    public String getName() {
        return this.name;
    }

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

    @ManyToOne(cascade = ALL)
    public Part getMainPart() {
        return mainPart;
    }

    public void setMainPart(Part mainPart) {
        this.mainPart = mainPart;
    }

    @OneToMany(cascade = ALL)
    @JoinColumn(name = "mainPart_id", referencedColumnName = "id")
    @Cache(usage = CacheConcurrencyStrategy.READ_WRITE)
    public List<Part> getParts() {
        return parts;
    }

    public void setParts(List<Part> parts) {
        this.parts = parts;
    }

}

CacheDao:

package com.cache.dao;

import java.util.List;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;

import com.cache.dataobject.Part;

/**
 * Session Bean implementation class CacheDao
 */
@Stateless(mappedName = "ejb/CacheDao")
public class CacheDao implements CacheDaoRemote {

    @PersistenceContext(unitName="CacheProjectUnit")
    EntityManager em;

    /**
     * Default constructor. 
     */
    public CacheDao() {
        // TODO Auto-generated constructor stub
    }

    public Part addPart(Part part){
        System.out.println("CALLED PERSIST");
        em.persist(part);
        return part;
    }

    public Part updatePart(Part part){
        System.out.println("CALLED MERGE");
        em.merge(part);
        return part;
    }

}

Test Client Code:

package com.cache.dao;

import java.util.ArrayList;
import java.util.List;

import javax.naming.InitialContext;
import javax.naming.NamingException;

import com.cache.dao.CacheDaoRemote;
import com.cache.dataobject.Part;


public class test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        InitialContext ctx;
        try {
            ctx = new InitialContext();
            CacheDaoRemote dao = (CacheDaoRemote) ctx.lookup("ejb/CacheDao");
            Part computer = new Part();
            computer.setId(1);
            computer.setName("Computer");

            List<Part> parts = new ArrayList<Part>();

            Part cpu = new Part();
            cpu.setId(2);
            cpu.setName("CPU");

            Part monitor = new Part();
            monitor.setId(3);
            monitor.setName("Monitor");

            parts.add(cpu);
            parts.add(monitor);

            computer.setParts(parts);

            dao.addPart(computer);

            computer.setName("DellComputer");

            dao.updatePart(computer);


        } catch (NamingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }

}

Persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="1.0"
    xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd">
    <persistence-unit name="CacheProjectUnit">
        <provider>org.hibernate.ejb.HibernatePersistence</provider>
        <!-- JNDI name of the database resource to use -->
        <jta-data-source>jdbc/H2Pool</jta-data-source>
        <properties>
            <!-- The database dialect to use -->
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect" />
            <!-- drop and create tables at deployment -->
            <property name="hibernate.hbm2ddl.auto" value="create-drop" />
            <property name="hibernate.max_fetch_depth" value="3" />
            <property name="hibernate.cache.provider_class" value="org.hibernate.cache.EhCacheProvider" />
        </properties>
    </persistence-unit>
</persistence>

EhCache.xml

<ehcache>
    <diskStore path="java.io.tmpdir"/>

    <defaultCache
            maxElementsInMemory="10000"
            eternal="false"
            timeToIdleSeconds="120"
            timeToLiveSeconds="120"
            overflowToDisk="true"
            diskPersistent="false"
            diskExpiryThreadIntervalSeconds="120"
            memoryStoreEvictionPolicy="LRU"
            />


    <cache name = "com.cache.dataobject.Part"
        maxElementsInMemory="100000"
        eternal="true"
        diskPersistent="false"
        timeToIdleSeconds="0"
        timeToLiveSeconds="0"
    />


    <cache name = "com.cache.dataobject.Part.parts"
        maxElementsInMemory="100000"
        eternal="true"
        diskPersistent="false"
        timeToIdleSeconds="0"
        timeToLiveSeconds="0"
    />


</ehcache>

Output Log:

INFO: CALLED PERSIST
FINEST: Cache lookup: com.cache.dataobject.Part#1
FINE: key: com.cache.dataobject.Part#1
FINE: Element for com.cache.dataobject.Part#1 is null
FINEST: Cache miss: com.cache.dataobject.Part#1
FINEST: Cache lookup: com.cache.dataobject.Part#2
FINE: key: com.cache.dataobject.Part#2
FINE: Element for com.cache.dataobject.Part#2 is null
FINEST: Cache miss: com.cache.dataobject.Part#2
FINEST: Cache lookup: com.cache.dataobject.Part#3
FINE: key: com.cache.dataobject.Part#3
FINE: Element for com.cache.dataobject.Part#3 is null
FINEST: Cache miss: com.cache.dataobject.Part#3
FINEST: Invalidating: com.cache.dataobject.Part.parts#1
FINE: key: com.cache.dataobject.Part.parts#1
FINE: Element for com.cache.dataobject.Part.parts#1 is null
FINE: insert into Part (mainPart_id, PART_NAME, id) values (?, ?, ?)
FINE: insert into Part (mainPart_id, PART_NAME, id) values (?, ?, ?)
FINE: insert into Part (mainPart_id, PART_NAME, id) values (?, ?, ?)
FINE: update Part set mainPart_id=? where id=?
FINE: update Part set mainPart_id=? where id=?
FINEST: Inserting: com.cache.dataobject.Part#1
FINE: key: com.cache.dataobject.Part#1
FINE: Element for com.cache.dataobject.Part#1 is null
FINEST: Inserted: com.cache.dataobject.Part#1
FINEST: Inserting: com.cache.dataobject.Part#2
FINE: key: com.cache.dataobject.Part#2
FINE: Element for com.cache.dataobject.Part#2 is null
FINEST: Inserted: com.cache.dataobject.Part#2
FINEST: Inserting: com.cache.dataobject.Part#3
FINE: key: com.cache.dataobject.Part#3
FINE: Element for com.cache.dataobject.Part#3 is null
FINEST: Inserted: com.cache.dataobject.Part#3
FINEST: Releasing: com.cache.dataobject.Part.parts#1
FINE: key: com.cache.dataobject.Part.parts#1

INFO: CALLED MERGE
FINEST: Cache lookup: com.cache.dataobject.Part#1
FINE: key: com.cache.dataobject.Part#1
FINEST: Cache hit: com.cache.dataobject.Part#1
FINEST: Cache lookup: com.cache.dataobject.Part#1
FINE: key: com.cache.dataobject.Part#1
FINEST: Cache hit: com.cache.dataobject.Part#1
FINEST: Cache lookup: com.cache.dataobject.Part#2
FINE: key: com.cache.dataobject.Part#2
FINEST: Cache hit: com.cache.dataobject.Part#2
FINEST: Cache lookup: com.cache.dataobject.Part#2
FINE: key: com.cache.dataobject.Part#2
FINEST: Cache hit: com.cache.dataobject.Part#2
FINEST: Cache lookup: com.cache.dataobject.Part#3
FINE: key: com.cache.dataobject.Part#3
FINEST: Cache hit: com.cache.dataobject.Part#3
FINEST: Cache lookup: com.cache.dataobject.Part#3
FINE: key: com.cache.dataobject.Part#3
FINEST: Cache hit: com.cache.dataobject.Part#3
FINEST: Cache lookup: com.cache.dataobject.Part.parts#1
FINE: key: com.cache.dataobject.Part.parts#1
FINEST: Cached item was locked: com.cache.dataobject.Part.parts#1
FINE: select parts0_.mainPart_id as mainPart3_1_, parts0_.id as id1_, parts0_.id as id18_0_, parts0_.mainPart_id as mainPart3_18_0_, parts0_.PART_NAME as PART2_18_0_ from Part parts0_ where parts0_.mainPart_id=?
FINEST: Caching: com.cache.dataobject.Part.parts#1
FINE: key: com.cache.dataobject.Part.parts#1
FINEST: Cached: com.cache.dataobject.Part.parts#1
FINEST: Invalidating: com.cache.dataobject.Part.parts#2
FINE: key: com.cache.dataobject.Part.parts#2
FINE: Element for com.cache.dataobject.Part.parts#2 is null
FINEST: Invalidating: com.cache.dataobject.Part.parts#3
FINE: key: com.cache.dataobject.Part.parts#3
FINE: Element for com.cache.dataobject.Part.parts#3 is null
FINEST: Invalidating: com.cache.dataobject.Part.parts#1
FINE: key: com.cache.dataobject.Part.parts#1
FINEST: Invalidating: com.cache.dataobject.Part#1
FINE: key: com.cache.dataobject.Part#1
FINE: update Part set mainPart_id=?, PART_NAME=? where id=?
FINE: update Part set mainPart_id=null where mainPart_id=?
FINE: update Part set mainPart_id=null where mainPart_id=?
FINEST: Updating: com.cache.dataobject.Part#1
FINE: key: com.cache.dataobject.Part#1
FINEST: Updated: com.cache.dataobject.Part#1
FINEST: Releasing: com.cache.dataobject.Part.parts#2
FINE: key: com.cache.dataobject.Part.parts#2
FINEST: Releasing: com.cache.dataobject.Part.parts#3
FINE: key: com.cache.dataobject.Part.parts#3
FINEST: Releasing: com.cache.dataobject.Part.parts#1
FINE: key: com.cache.dataobject.Part.parts#1

Have you tried the Hibernate list? – Jonathan Parker Mar 18 '09 at 03:24 — Jonathan Parker, Mar 18 '09 at 03:24
Yes I have.. Still waiting for something from them. – mainstringargs Mar 18 '09 at 13:06 — mainstringargs, Mar 18 '09 at 13:06

Chris Kimpton · Answer 1 · 2009-03-30T06:10:21.440

You've probably seen this already, but there is an open Hibernate bug that seems to relate to your problem - "2nd level cached collections are locked causing a cache miss"..

From that bug, the fix may be to use a new session for your add/update calls. You can get an EntityManagerFactory rather than EntityManager and request a new Entity Manager for each call. Obviously it depends on the wider context of your code as to how appropriate this is.

"Cached Item Was Locked" causing Select Statement in Hibernate

1 Answers1