Re: v$access + latch free(library cache) BUG???
- From: "Leyi Zhang" <kamusis@xxxxxxxxx>
- To: steve.adams@xxxxxxxxxxxx
- Date: Tue, 28 Feb 2006 10:11:53 +0800
But just "desc v$access" caused so notable contention is also a common
situation?
I even can't catch "latch free" wait events from v$session_wait when I run
"desc v$access" in our database, we just have 200 connections.
On 2/28/06, Steve Adams <steve.adams@xxxxxxxxxxxx> wrote:
>
> Hello Syed,
>
> Any access to V$ACCESS on an instance with 1000+ connections creates at
> least short term contention for the library cache latches. That is not a
> bug. It is a consequence of all the work that is needed to instantiate
> the view. With your system already suffering contention for another
> latch, it is not strange that any reference to V$ACCESS would induce
> severe library cache latch contention. In short, I don't think that this
> is a bug.
>
> @ Regards,
> @ Steve Adams
> @ http://www.ixora.com.au/ - For DBAs
> @ http://www.christianity.net.au/ - For all
>
>
> The Human Fly wrote:
> > Hello list,
> >
> > We have faced a very very strange problem when accessing or desc
> v$access table.
> >
> > Database : Oracle 9i Rel.2 (9205)
> > OS : AIX 5.3 JFS2 Filesystem.
> > CPU = 30+
> > No. Connections = 1000+
> >
> > We are facing problem with latch free (cache buffer chains), when the
> > problem occurs, cpu becomes 0% ideal and we kill some process from
> > which transaction are coming.
> >
> > I just desc v$access from the sql prompt, and strangly, all the
> > session are started waiting on 'latch free' and this time its was
> > library cache and when I kill the session which was desc v$access,
> > then, everything comes normal.
> >
> > It was not just an accident, I can still reproduce the same error.
> > Whatever action I do on v$access, this is causing. If this was a bug,
> > we have same OS server, same oracle version for another database,
> > where this doesn't happens. The only differene between these two
> > databases are just no. of cpus.
> >
> > It is really drawing me crazy. Does anyone has experience the same?
> >
> > --
> > Best Regards,
> > Syed Jaffar Hussain
> [snip]
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
--
Kamus <kamusis@xxxxxxxxx>
Oracle8i & 9i Certified DBA from China
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