Resolving "ORA-12516, TNS:listener could not find available handler with matching protocol stack"

While testing a WSO2 G-Reg pack pointing to an Oracle database (with ojdbc6.jar), came up with the below exception

Caused by: oracle.net.ns.NetException: Listener refused the connection with the following error: ORA-12516, TNS:listener could not find available handler with matching protocol stack at oracle.net.ns.NSProtocol.connect(NSProtocol.java:399) at oracle.jdbc.driver.T4CConnection.connect(T4CConnection.java:1140) at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:340) ... 88 more 

In addition to that, noticed the below warning as well.
  TID: [0] [Greg] [2014-07-11 18:31:52,652] WARN {java.util.prefs.FileSystemPreferences} - Couldn't flush system prefs: java.util.prefs.BackingStoreException: Couldn't get file lock. {java.util.prefs.FileSystemPreferences}

So after doing some googling, I found out about the below parameter and added it to the server start-up script solves the issue. You can read more about this on http://allaboutbalance.com/articles/disableprefs/.

-Djava.util.prefs.syncInterval=2000000 \