Re: Researching latch efficiency
- From: "Jared Still" <jkstill@xxxxxxxxx>
- To: anjo.kolk@xxxxxxxxxxx
- Date: Sat, 28 Jun 2008 13:57:53 -0700
So let's hear more about "oradebug dump messages".
Maybe a URL for your presentation?
I haven't been to IOUG for a few years now, or I would have
seen the presentation. :)
Jared
On Sat, Jun 28, 2008 at 12:45 PM, Anjo Kolk <anjo.kolk@xxxxxxxxxxx> wrote:
> People,
>
> Symptoms vs problems. Latch waits are always symptoms of the real problem.
> So this particular latch is a symptom because the shadows sending many
> messages to the background processes. Normally this would be LGWR and/or
> the
> DBWR. Dumping the messages (oradebug dump messages and x$message have the
> answers). Hmmm didn't I do a presentation on this 3-4 years ago during IOUG
> :)
>
> Anjo.
>
>
> Op 6/21/08 3:21 PM, Yong Huang <yong321@xxxxxxxxx> schreef:
>
> > Anjo Kolk's wait event article is still the most complete about
> documenting
> > latches. Search for it on Google.
> >
> > messages
> >
> > There is a pool of message blocks in the SGA. This pool is controlled by
> the
> > init.ora parameter _messages. If a process needs a message it will get
> the
> > latch, search a linked list for a free message block, unlink this message
> > block
> > , put this message on the message queue for the intended process and then
> > release this latch. The event rdbms ipc message indicates that a process
> is
> > waiting for a message to arrive on his message queue. The event rdbms ipc
> > message reply is used to indicate that a message is expected back by the
> > sending process.
> >
> > Why not compare the numbers in Spotlight and sqlplus? If they're close,
> they
> > must be referring to the same event.
> >
> > Yong Huang
> >
> >> I'm using Quest's Spotlight and wonder if it means "latch: messages". I
> >> may need to open a ticket with Quest Support to explain the display in
> >> their GUI.
> >>
> >> Not sure if this is the one I'm waiting on. I'll look deeper.
> >>
> >> sql> select * from v$event_name where name = 'latch: messages';
> >>
> >> The online Oracle doc referenced by Jared (thanks J!) does not have all
> >> 889 wait events documented for 10.2.0.4. I doubt I'm gonna find it.
> :-)
> >
> >
> >
> >
> >
> > --
> > //www.freelists.org/webpage/oracle-l
> >
> >
>
>
> --
> //www.freelists.org/webpage/oracle-l
>
>
>
--
Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist
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