Same issue came by as in, my oracle connection would go upto jdbcTemplate.executeUpdate() and then nothing, no error/exception no
thread to debug.
So I closed my oracle sql developer, then tried persisting, so it worked. It seems as the oracle DB is logged in by the
java as Functional user and then if one has sql developer open at the same time, the oracle connection sessions seem to get overridden so sessions get locked.
There could be more to this but stopping the sql developer at the time worked and it is still working and gives error sometimes when you have stopped a java program that opened a connection but didnt yet finish before you terminate it. I am sure there are timeouts to unused connections or locked connection. try stopping the oracle sql developer.