From the documentation;
A deadlock occurs when two or more session are waiting for data locked by each other, resulting in all the sessions being blocked. Oracle automatically detects and resolves deadlocks by rolling back the statement associated with the transaction that detects the deadlock.
Usually any of the connections involved in the deadlock dies and one of them receives the following error;
ORA-00060: deadlock detected while waiting for resource
Today we have been reported that a Tibco adapter has fallen, a Tibco adapter is basically a connection pool from an application, in this case the pool opens 20 connections to a database. Looking at alert.log and trace files, it appears that also died the shared server. The two processes have been involved in deadlock.
The shared server process has died, possibly by a bug that we reported to MOS. The pool has died because of the connection will be received an ORA-00060 and has failed to treat, knocking all the pool
So 21 connections have fallen ….
HTH – Antonio NAVARRO