RE: Rollback waiting on 'cache buffer chains' latch

Allen,

Have you checked that v$session.wait_time=0 for sid=664, i.e. that this session is actually in wait right now?

Is there any news from PMON in the alert.log & pmon's .trc? Probably PMON is in trouble or too busy with rollback of some other session(s). AFAIK it rolls back 20 undo blocks at once than sleeps etc.

HANGANALYZE also may give you some clue on what is going on there. The steps are

sqlplus "/ as sysdba"
oradebug setmypid
oradebug hanganalyze 3
oradebug tracefile_name
exit

You can search the trace with the sid number of the problem session and the sid number of PMON.

One more thing to check - if that session is part of distributed transaction. Check v$lock for 'DX' type of lock. If this is the case, probably you'll need an access to remote db and kill appropriate process there.

If PMON isn't in trouble then probably (! think twice !) you may wake up the PMON (via oradebug wakeup)

Seems, I'm a bit late, but HTH.

• Andrey

On Wed, January 10, 2007 00:03, Allen, Brandon wrote:
> I forgot to mention the basics: 9.2.0.8 on AIX5.2
>
> ________________________________
>
> From: Allen, Brandon
> Sent: Tuesday, January 09, 2007 2:01 PM
> To: oracle-l
> Subject: Rollback waiting on 'cache buffer chains' latch
>
>
> Hi List,
>
> I've got a production database that currently has a terminated session
> stuck in the rollback state and v$session_wait shows it is waiting on
> 'latch free' for the 'cache buffer chains' latch. This hung session is
> holding several locks that are blocking other users so I'd like to get
> it cleared out ASAP, but I'm not sure how to do that. V$transaction
> only shows 69 for used_ublk and it's not changing. I've already opened
> an SR and am awaiting Oracle's response and also still researching &
> troubleshooting on my own, but thought I'd see if any of you folks have
> an answer or any suggestions.
>
> Thanks,
> Brandon
>

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