Oracle: Shutdown Immediate hangs

So, I Issued a shutdown immediate today, and it sat there for almost 2 hours. As per Oracle documentation, its waiting for all the active transaction to finish...

My database has more than 30 schemas, and I probably have too many inactive connections, and hence the long wait.
 
All I could see in Alert log was "Active call for process xxxx user 'SYSTEM' program 'ORACLE.EXE (SHAD)'"

After 2 hours waiting, I gave up and started a second session and issued a Shutdown Abort.



Though this is not a bug, I was not sure how long I had to wait for all the active transactions to complete.

So, If you are planning to shutdown Immediate, make sure to query v$session for any active session, and notify the users and kill all "INACTIVE" connections.