Locking problem

behrangsa · **Posted:** Tue Apr 10, 2007 9:26 am

Hi,

NOTE: This is actually the simplified version of a real-world problem I have faced in developing a Web app.

I have a simple persistent class named Language:

Code:

<hibernate-mapping>
    <class name="com.behrangsa.data.Language" table="language">
        <id name="id" column="id">
            <generator class="native" />
        </id>
        <property name="title" length="50" not-null="true"/>
    </class>
</hibernate-mapping>

Suppose that I want to save two instances of Language, one in the current session, the other one in another session:

Code:

SessionFactory factory = HibernatePractice.getSessionFactory();
Session currentSession = factory.getCurrentSession();
currentSession.beginTransaction();

Language lang1 = new Language();
lang1.setTitle("Language 1");
currentSession.save(lang1);

Session secondSession = factory.openSession();
secondSession.beginTransaction();
Language lang2 = new Language();
lang2.setTitle("Language 2");
secondSession.save(lang2);
secondSession.getTransaction().commit();

currentSession.getTransaction().commit();

Now when I try to execute the above code, I encounter the following exception:

Code:

Caused by: java.sql.SQLException: Lock wait timeout exceeded; try restarting transaction
   at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2921)
...

As long as I know MySQL 4.1.x uses row level locking, so I though that this shouldn't be an issue. Any ideas what is the problem with the above code?

Thanks in advance,
Behrang