Re: Help: infinite loop creating trace file hangs database

Buffer Cache at level 9 is a peculiar value. It's trying to dump a full description of every used buffer in your buffer cache, which is why it is running up CPU so aggressively, and since you stop writing trace file at 5M, there's nothing stopping it swamping your system.

The only thing I can think of that would do this is an event set in your init.ora that was put there to trace some old problem and
has been forgotten about.

Check for lines like:

event ='mmm trace name buffers level 9'

(I've probably got the syntax wrong - but the general idea should be close enough).

-- 
Regards

Jonathan Lewis
http://www.jlcomp.demon.co.uk

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The Co-operative Oracle Users' FAQ
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> On 13 Jan 2004 13:00:10 -0700, nothome_at_spammers.are.scum (Malcolm

> Dunnett) wrote:

>

> >

> > I have an Oracle 8.1.7.4 server.

> >

> > Occasionally ( usually once every few months, but twice in

> >the last week ) one of the foreground server processes will

> >crash. When it does it creates a trace file which says it

> >is doing a "Dump of buffer cache at level 9". This creates

> >a trace file of about 5MB. The problem is that at the point

> >where 5MB of trace information is created the process appears

> >to go into an infinite CPU loop ( in one instance it was still

> >running 14 hours later ). The process appears to be holding

> >some locks as when it goes into this loop all the other server

> >processes eventually hang. Killing the process doing the

> >dump causes all the other server processes to resume normally.

> >

> > While there is clearly some bug that is causing the server

> >process to crash the more immediate problem is that the cpu

> >loop/locks cause it to effectively hang the entire database

> >when it does. Is there a way to prevent this dying process from

> >taking this buffer dump ( or to prevent the buffer dump from

> >going into an infinite loop )?

> >

> > There are no error reported in the alert log when this occurs.