START WITH/CONNECT BY issue in DB 11.1.x

If you run recursive sql in the oracle db 11.1.x, you probably meet issue like this:

Internal Exception: java.sql.SQLException: Closed Connection, it is a bug in this DB version.

you have 2 options to fix the issue:

1. login sqlplus as sys admin , run the command :
     alter system set "_optimizer_connect_by_cost_based" =FALSE;

2. upgrade the db to 11.2.x.