"Cached Item Was Locked" causing Select Statement: Hibernate + EHCache
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Posted By:   mark_cloutier
Posted On:   Sunday, March 15, 2009 05:57 PM

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 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 Dow   More>>

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



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 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 getParts() {
return parts;
}

public void setParts(List 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 parts = new ArrayList ();

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();
}

}

}




			<?xml version="1.0" encoding="UTF-8"?>
			

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">

org.hibernate.ejb.HibernatePersistence

jdbc/H2Pool














			



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



maxElementsInMemory="100000"
eternal="true"
diskPersistent="false"
timeToIdleSeconds="0"
timeToLiveSeconds="0"
/>



maxElementsInMemory="100000"
eternal="true"
diskPersistent="false"
timeToIdleSeconds="0"
timeToLiveSeconds="0"
/>





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.
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