orakill tips

In Windows, there are a couple of kill utilities: the Oracle-centric "orakill" utility and the Windows taskkillprogram.  If the session cannot be killed more gracefully via alter system kill session, or the instance is inaccessible via SQL, then orakill should be used to terminate the offending session. 

Access to the Windows machine containing the database must be secure to use orakill. Any user with access to the box could access orakill or the Windows Task Manager and damage database processes.

Oracle on Windows is implemented based upon threads rather than processes. So when the Windows Task Manager is viewed, all that will be seen is one ORACLE.EXE for that database instance. The individual threads for the sessions will not be visible since Task Manager only shows the process and number of threads. Look at the next screen snapshot; there are two SQL*Plus sessions connected to the database on this Windows box.

Even though two sqlplus.exe processes can be seen, there is but one oracle.exe process. One would need to dig deeper than the basic Windows task management program to find the Oracle dedicated database server process? thread.

The DBA could use a utility program, such as the free QuickSlice (qslice.exe) and PStat(pstat.exe) from the Microsoft's Resource Kit, or Process Explorer  (procexp.exe), also from Microsoft.

With tools like these, open the oracle.exe process and investigate into its many threads. However, if one simply selects the 1176 thread using Process Explorer and presses the KILL button, there could be a problem. These tools do not inform Oracle's PMON as to what just occurred, so they do not always make a hanging session and its locks go away.

It still may be necessary to also manually run oradebugwakeup 1 to clear the locks, v$sessionand v$process. Hence, it is advisable to always use the Oracle- provided orakillutility instead. Just be careful, because if the wrong thread, such as a background process, is chosen, then the entire database may crash.

The Windows command to kill this session with orakill would be as follows:

C:\oracle9i\bin>orakill ORCL92 768

In this example, the Windows thread corresponding to the Oracle session can be killed in the operating system without ever logging into the database. For another example, the Windows command to kill a session would be:

C:\oracle9i\bin>orakill ORCL92 768

In this example, the thread (Oracle session) was killed in the operating system without ever logging into the database. Before killing the session, the DBA may decide to view the SQL being executed by the session. This can be obtained by using the TID above (300) in the following SQL statement:

select
   b.username, a.sql_text
from
v$sqltext_with_newlines a, v$session b, v$process c
where
   c.spid = to_number('300', 'xxx')
and
   c.addr = b.paddr
and
   b.sql_address = a.address;  

The orakillcommand is very simple. In fact, it is essentially the exact same syntax as the ALTER SYSTEM KILL SESSION. This means that it accepts two parameters - the SID and v$process.spid - which represents the thread number.

C:\Temp>orakill OR0310 1176

Kill of thread id 1176 in instance OR0310 successfully signaled.

This is an excerpt from the book "Oracle Utilities", and you an get it directly from the publisher for 30%-off at the link.