Error with Oracle hanging on a stored procedure call or commit statement.
Does someone have an uncommitted session? SQL Developer will sometimes cause this (maybe a user doesn’t have autocommit on?).
select s.seconds_in_wait, s.blocking_instance, s.blocking_session, s.event, t.start_time, s.sid, s.serial#, s.username, s.status, s.schemaname, s.osuser, s.process, s.machine, s.terminal, s.program, s.module, to_char(s.logon_time,'DD/MON/YY HH24:MI:SS') logon_time from v$transaction t, gv$session s where s.saddr = t.ses_addr order by start_time;
Once you have a session id, use
Sql Developer Tools > Monitor Sessions to see the problem SQL
See also this link on StackOverflow.