You have to create a pool connections
Anyway, I don't understand why do you should synchronizate. A RDBM
can manipulate n numbers of connections without problems.
To synchronize the threads means that you have to force some to wait.
mm follow the steps that other did it.
Please check this site
The Apache Tomcat 5.5 Servlet/JSP Container - JNDI Datasource HOW-TO