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Re: Oracle Processes Stalling Problem

From: Robert Pritchard <robert_pritchard_at_tertio.com>
Date: Tue, 02 Feb 1999 17:58:49 +0000
Message-ID: <36B73CD9.BC8B8881@tertio.com>


We have checked the OS angle, which is what Oracle support first suspected and recommended some patches to be installed however the problem still occured.

It doesn't appear to be a memory problem as I would have expected errors to beign to appear as the system failed, and that doesn't happen.

We did suspect breifly that it may be due to a memeory leak in one of the fundamental control processes but that now seems unlikely, and again should have caused an error.

Cheers
Rob

mark.powell_at_eds.com wrote:

> In article <36B040DB.1249F205_at_tertio.com>,
> Robert Pritchard <robert_pritchard_at_tertio.com> wrote:
> > That is pretty much the format we use for each transaction, althouhg each
> > process connects to the database when it is initially started rather than at
> > each transaction.
> > Each transaction commits after it is complete.
> >
> > There are no errors occuring that I can find (and I've sent the logs from the
> > stalled database to Oracle support and they have not found anything either)
> > such as resource busy
> >
> > The process that hangs doesn't crash or report any error, it just sits there
> > stuck on its select.
> >
> > There are no foreign keys defined on the table.
> >
> > Thanks
> > Rob
> > (feel free to email me direct if you have any suggestions, as I am totally
> > clueless!).
> >
> > Jean-Claude Matarazzo wrote:
> >
> > > 1. Perhaps, you have a problem of transaction, how do you do your
> > > transaction :
> > > __________________________________________________________
> > >
> > > CONNECT user/password
> > >
> > > select * from YOUR_TABLE where a_condition FOR UPDATE OF a_column NOWAIT;
> > >
> > > IF there is an error ORA-0054 : resource busy .. your record is locked.
> > > ELSE
> > > update YOUR_TABLE set a_column=new_value where a_condition ;
> > >
> > > COMMIT;
> > >
> > > The first transaction begin at the connection and ended with COMMIT or
> > > rollback.
> > > After doing a commit or rollback, another transaction begin...
> > >
> > > All the errors are returned, are you sure ?
> > >
> > > 2. Have you foreign keys on the table you want to lock ?
> > > ________________________________________
> > >
> > > Robert Pritchard a écrit:
> > >
> > > > I am currently attempting to track down a very puzzling bug in a oracle
> > > > accessing system.
> > > > The problem is that after a certain period of time the entire thing
> > > > hangs up. This is based on Oracle 7.2.3 running on a HP 10.20 box with
> > > > all the relevant recommended patches installed.
> > > > The system itself comprises of a total of 44 tables which are accessed
> > > > by a number of different processes (the database access is done using
> > > > Pro C). The stall alwasy seems to occur on a SELECT FOR UPDATE on a
> > > > particular table. The table in question is simply a counter containing
> > > > three rows, which are updated by three seperate processes (and accessed
> > > > but not altered by a fourth) after they have completed their relevant
> > > > tasks. Has far as I can tell there are no conflicting locks, Oracle
> > > > itself returns no deadlock or other error and the problem still occcurs
> > > > when the NOWAIT parameter is included.
> > > > This has had myself and Oracle support stumped for a while now. I have
> > > > sent them all the trace logs and relevant lock table output etc so it is
> > > > nothing obvious.
> > > > I would appreciate any insight anyone can offer.
> > > > Thanks
> > > > Rob
> >

>

> Maybe instead of looking at the obvious, select for update clause, it is an
> OS related problem. Have you verified that your system isn't running short
> of swap or freemem via sar? Then what about Oracle temporary space?
>

> You said 'everything hangs'. If this means all Oracle processes on the
> system then I would suspect some Os related process like part of the Oracle
> SGA or an Oracle process getting swaped out that has possession of a resource
> that the rest of the application queues up waiting for.
>

> Mark D. Powell -- The only advice that counts is the advice that
> you follow so follow your own advice --
>

> -----------== Posted via Deja News, The Discussion Network ==----------
> http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
Received on Tue Feb 02 1999 - 11:58:49 CST

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