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Thread: orakill utility

  1. #1
    Join Date
    Sep 2000

    What is orakill utility and how is it used.

    Is it to kill the background processes for the sessions?


  2. #2
    Join Date
    Aug 2000
    Toronto, Ontario Canada

    ALTER SYSTEM KILL SESSION command is used then and session status became
    "killed", but locks was not released.

    Killing the session will not clear the locks. The session on the remote
    database will remain idle waiting for input until the network read times
    out. Only then the kill session is processed, and locks are released.

    You can shutdown and restart the database or use the ORAKILL utility to kill
    threads, here is the usuage.

    Oracle has provided an ORAKILL utility that will kill shadow threads. Each
    user's connection is represented by a thread in the Oracle process. If a
    user's session is killed, then their Oracle session is killed - not the thread.
    Oracle has provided an ORAKILL utility which can be passed a thread ID and will
    kill the specified thread.

    To make sure you don't kill a background process (which would crash your database)
    you must perform a select to ensure you get the correct thread.

    select p.spid "OS Thread", b.name "Name/User", s.osuser, s.program
    from v$process p, v$session s, v$bgprocess b
    where p.addr = s.paddr
    and p.addr = b.paddr UNION ALL
    select p.spid "OS Thread", s.username "Name/User", s.osuser, s.program
    from v$process p, v$session s
    where p.addr = s.paddr
    and s.username is not null;

    This will list all Shadow processes and backgound processes.
    Each shadow process will show the thread ID - this is what must be killed via
    the ORAKILL utility.

    The kill session behavior is mentioned in the ORACLE7 Server Administrator's
    Guide (pg 4-13), but it doesn't say explicitly what happens to the session
    while it is in the KILLED PSEUDO) state. What's happening is that PMON
    periodically checks to see if any sessions have been killed.
    If it finds one, it attempts to rollback the transaction for that session (that
    was in progress when it was killed). The reason this can take a long time is
    because PMON may have more than one transaction to rollback at a time
    (if other sessions have been killed, or if processes have died,etc).
    Thus, it may take a while to finally cleanup the killed session and have it
    disappear from the session monitor. The system i/o monitor correctly shows
    the reads and writes being performed by PMON in order to rollback the
    session's transaction.

    PMON will not delete the session object itself until the client connected to
    that session notices that it has been killed. Therefore, the sequence of
    events is:

    1) alter system kill session is issued - the STATUS of the session object in
    V$SESSION becomes KILLED, its server becomes PSEUDO.

    2) PMON cleans up the *resources* allocated to the session
    (i.e., rolls back its transaction, releases its locks, etc).

    3) the entry in V$SESSION remains there until the client of that session (the
    client is the process associated with the OSUSER,MACHINE,PROCESS columns in
    the V$SESSION view) tries to do another request.

    4) the client attempts another SQL statement and gets back ORA 28.

    5) PMON can now remove the entry from V$SESSION.
    This behavior is necessary because the client still has pointers to the
    session object even though the session has been killed. Therefore, the
    object cannot be deleted until the client is no longer pointing at it.


  3. #3
    Join Date
    Feb 2000
    Washington DC
    C:\users\default>orakill /?

    Usage: orakill sid thread

    where sid = the Oracle instance to target
    thread = the thread id of the thread to kill

    The thread id should be retrieved from the spid column of a query such as:

    select spid, osuser, s.program from
    v$process p, v$session s where p.addr=s.paddr


  4. #4
    Join Date
    Sep 2000
    Thanks for the help guys.

    Is there any way we can find out the time lapse in which the pmon wakes up to remove the killed sessions and the shadow processes and is it configurable ?

    Thanks again

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