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Title
Getting the message "Session is marked for kill" when trying to kill a session in Toad. -
Description
When trying to kill a session from Toad's session browser (right click | Kill ) it gives the error "session is marked for kill". Why is the session not being killed immediately? -
Resolution
Toad sends out the Kill command, but it is Oracle that processes it. The message, "Alter system kill session... Session is marked for kill" means the session cannot be killed at the moment but will be killed as soon as the Oracle process is allowed on the Oracle end. This is an Oracle error message, not Toad specific. The session should eventually be killed by Oracle.
Based off of Oracle documentation, it is noted:
http://www.oracle-base.com/articles/misc/killing-oracle-sessions.php#kill_session
"The KILL SESSION command doesn't actually kill the session. It merely asks the session to kill itself. In some situations, like waiting for a reply from a remote database or rolling back transactions, the session will not kill itself immediately and will wait for the current operation to complete. In these cases the session will have a status of 'marked for kill'. It will then be killed as soon as possible.
In addition to the syntax described above, you can add the IMMEDIATE clause.
SQL> ALTER SYSTEM KILL SESSION 'sid,serial#' IMMEDIATE;
This does not affect the work performed by the command, but it returns control back to the current session immediately, rather than waiting for confirmation of the kill.
If the marked session persists for some time you may consider killing the process at the operating system level. Before doing this it's worth checking to see if it is performing a rollback. You can do this by running this script (session_undo.sql). If the USED_UREC value is decreasing for the session in question you should leave it to complete the rollback rather than killing the session at the operating system level."