java throw Connection reset exception when connecting to oracle database using jdbc

When java application connect to oracle 12c database using jdbc (run in rhel5), connection reset exception sometime will throw randomly.

java.sql.SQLRecoverableException: IO Error: Connection reset

Tested the same java in solaris, no such exception. Follow https://access.redhat.com/solutions/353653 tune jvm argument and run rngd daemon, issue persists. We tried everything we can do about this, no luck. Any one have any hints or idea what's going on?