Drop Temporary Tablespace Hangs

Problem Description
The DROP temporary tablespace operations take long time and in fact it hangs. If you take a 10046 trace of the session it shows "enqueue" wait.

Cause of The Problem In the section http://arjudba.blogspot.com/2008/05/operation-that-require-sort-area-or.html I discussed about the operation that needs sort space. Whenever an operation is using sort space an entry is found in the v$sort_usage. After the operation finishes entry from $sort_usage vanishes. But dead connections (while running a query) may leave entries in v$session (status inactive) and in v$sort_usage. The query about the users who is Performing Sort operation in Temp Segments can be found in http://arjudba.blogspot.com/2008/05/information-about-temporary-segments.html

Solution of The Problem
1.Create a new temporary tablespace and assign all users to this new tablespace. You can easily do this task on unix system as,
CREATE TEMPORARY TABLESPACE TEMP2 TEMPFILE '/oradata2/temp02.dbf' SIZE 100m;
Change it for all by
ALTER DATABASE DEFAULT TEMPORARY TABLESPACE TEMP2;

2.Find out the all the sessions that are not active and have an entry in V$sort_usage.
You can do it by,
SELECT b.tablespace,b.segfile#,b.segblk#,b.blocks,a.sid,a.serial#,
a.username,a.osuser, a.status
FROM v$session a,v$sort_usage b
WHERE a.saddr = b.session_addr;

3.Kill those session.
Using
alter system kill session 'SID_NUMBER, SERIAL#NUMBER'; kill those session that are not being used actually.
where SID_NUMBER and SERIAL#NUMBER is found in step 2.

4. Now dropping the previous tablespace
DROP TABLESPACE previous_temp_tbs;