10:19 a.m.
Clob management and deadlock
----------------------------
Key: HHH-2640
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-2640
Project: Hibernate3
Issue Type: Bug
Components: core
Affects Versions: 3.2.0.ga
Environment: JDK 1.5, Oracle 10g v2
Reporter: Samuel Emangard
Priority: Trivial
Attachments: Samuel.rar
Mapping documents:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
'-//Hibernate/Hibernate Mapping DTD 3.0//EN'
'http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd'>
<hibernate-mapping package="com.toluna.samuel.hibernate.emailtemplate">
<class name="EmailTemplate" table="EmailTemplate">
<id name="id" type="long">
<column name="template_id" not-null="true"/>
<generator class="native"/>
</id>
<property name="name">
<column name="email_name" not-null="false"/>
</property>
<property name="htmlTextClob" type="clob">
<column name="html_Text" not-null="false"/>
</property>
<property name="plainTextClob" type="clob">
<column name="plain_Text" not-null="false"/>
</property>
</class>
</hibernate-mapping>
Extract also of my Java bean:
ublic class EmailTemplate {
private long id;
private String name;
private String plainText = " ";
private String htmlText = " ";
private Clob plainTextClob;
private Clob htmlTextClob;
...
Code of the test case:
Session ss = HibernateUtil.getSessionFactory().getCurrentSession();
//S_LOGGER.debug("Number of current Hibernate sessions: "+
HibernateUtil.getSessionFactory().getStatistics().getSessionOpenCount());
ss.getTransaction().begin();
EmailTemplate et = (EmailTemplate) ss.load(EmailTemplate.class, new
Long("299941536982302"));
S_LOGGER.debug(et.getName());
Thread.sleep(5000);
S_LOGGER.debug("BEFORE FLUSH");
ss.flush();
S_LOGGER.debug("AFTER FLUSH");
ss.getTransaction().commit();
The generated SQL :
The load statement is always generated:
/* load com.toluna.samuel.hibernate.emailtemplate.EmailTemplate */ select
emailtempl0_.template_id as template1_0_0_,
emailtempl0_.email_name as email2_0_0_,
emailtempl0_.html_Text as html3_0_0_,
emailtempl0_.plain_Text as plain4_0_0_
from
EmailTemplate emailtempl0_
where
emailtempl0_.template_id=?
....
Depending on the implementation of the getter, the following update statement is
generated:
/* update
com.toluna.samuel.hibernate.emailtemplate.EmailTemplate */ update
EmailTemplate
set
email_name=?,
html_Text=?,
plain_Text=?
where
template_id=?
Here is the getter:
Clob getHtmlTextClob() {
//1-
//return Hibernate.createClob(htmlText != null ? htmlText : " ");
//2-
return htmlTextClob;
}
With 1- the update statement is generated
With 2- the update statement is not generated
Why?
Extract of the setter:
void setHtmlTextClob(Clob htmlTextClob) {
this.htmlTextClob = htmlTextClob;
try {
if (htmlTextClob != null) {
htmlText = HibernateUtil.getStringFromClob(htmlTextClob);
//htmlText = "samuel";
} else
htmlText = "";
} catch (SQLException e) {
throw new RuntimeException(e);
} catch (IOException e) {
throw new RuntimeException(e);
}
}
I have also another more critical issue which seems tied to the previous:
If I write the following piece of test code instead of the one shown above:
Session ss = HibernateUtil.getSessionFactory().openSession();
//S_LOGGER.debug("Number of current Hibernate sessions: "+
HibernateUtil.getSessionFactory().getStatistics().getSessionOpenCount());
EmailTemplate et = (EmailTemplate) ss.load(EmailTemplate.class, new
Long("299941536982302"));
S_LOGGER.debug(et.getName());
Thread.sleep(5000);
S_LOGGER.debug("BEFORE FLUSH");
ss.flush();
S_LOGGER.debug("AFTER FLUSH");
As you can see in this piece of code i do not manage transactions explicitly and in that
case my 2 java threads generated update statements which never ended: there was a deadlock
on the DB.
During the last test, If I still did not manage transactions explicitly but I modified the
getter like that:
Clob getHtmlTextClob() {
return htmlTextClob;
}
Then neither update statements nor deadlock were generated.
I wrote this piece of test code to reproduce deadlock I was facing on my Jonas server.
Could you please help me to understand this behaviour?
Here is anextract of my hibernate.cfg.xml:
<property
name="connection.url">jdbc:oracle:thin:@192.168.2.7:1521:tlorcl1</property>
<property name="connection.username">samuel</property>
<property name="connection.password">toluna</property>
<property
name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
<property
name="dialect">org.hibernate.dialect.Oracle9Dialect</property>
<property name="hibernate.show_sql">true</property>
<property name="hibernate.format_sql">true</property>
<property name="hibernate.use_sql_comments">true</property>
<property name="myeclipse.connection.profile">QA</property>
<property name="current_session_context_class">thread</property>
Thanks in advance
Regards
Samuel
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