Today I had a problem with a private database link between two databases. The user reports that running a simple “desc firstname.lastname@example.org” doesn’t work. Currently in the source database are three sessions hung. If we look at that do these sessions, we can see that are waiting for the event single-task message.
This event usually occurs across the database link connection. We tried to perform a tnsping to check the listener.
Tnsping command doesn’t reply, so we can determine that the problem is the listener, try perform a lsnrctl status but not responding so we opted to finish the process with the command “kill -9” since we are on unix platform and restart the listener. In the source database the first three sessiones continue unanswered so we kill, in this case from database.
The kill command reply “ORA-00031: session marked for kill”. The sessions continue but do not die, so we kill them using kill command from Operating System .