MySQL connections not closing

I have a web application running on Tomcat7 that connects to MySQL 5.5.

I have two servers running the identical code:

• Ubuntu

• Red Hat

The Ubuntu one runs fine maintaining a steady 8-16 connections, but the Red Hat one leaks connections and the connection count grows, never going down. The server eventually resets ~152 connections and the cycle repeats.

The code to close the connection is getting called:

try {
    conn.close();           
} catch (SQLException e) {
    exceptionController.logException(this.getClass().getSimpleName(), "finalize Db", e.getMessage(), false);
}finally{
    conn = null;
}

Why the difference in behavior? Are there configuration settings that I should be condsidering?