Re: Query against V$SESSION hangs on 10g RAC systems

I'm just taking a wild guess here, but to get blocking sessions it's possible the query of v$session would have to go to the other node(s) of the RAC cluster for session information, since the blocking session may be on a different node. 60 seconds is the time RHEL RAC takes to time out if a node cannot be reached, which could explain that exact timeout.

Why the query works sometimes and not others, I don't know. Bug?

Finn

On 11/2/07, M Rafiq <rafiq9857_at_hotmail.com> wrote:
>
>
> I ran this query on a non rac 10.2.0.3 database and it returned the rows
> very quickly. It may be some RAC related issue.
>
> Regards
> Rafiq
>
>
>
> ------------------------------
> Date: Fri, 2 Nov 2007 08:35:40 +0100
> From: exriscer_at_gmail.com
> To: snowman327_at_gmail.com
> Subject: Re: Query against V$SESSION hangs on 10g RAC systems
> CC: oracle-l_at_freelists.org
>
> hi
>
> querying blocking_session is the problem, if you dont query that columnd
> then it should be fine
>
> I have a customer who requested a backport to fix the bug but the one-off
> patch has no effect so might have to wait until 10.2.0.4
>
> thanks
>
> --
> LSC
>
>
>
> On 11/1/07, *Dean* <snowman327_at_gmail.com> wrote:
>
> We recently had a locking/blocking problem on two different 10.2.0.3 RAC
> systems. I ran a query similar to below to get more information:
>
> select sid, serial#, program, module, action, username, osuser,
> sql_hash_value, machine, event, blocking_session
> from v$session
> where status='ACTIVE';
>
> About 1 out of 5 times this query hangs. When it hangs, it waits for
> exactly 60 seconds on "DIAG idle wait" and then returns the result set. If
> I remove the blocking_session column, this query runs fine and never hangs.
> Has anyone run into this or have any ideas why this would happen?
>
>
>
>
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