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Home -> Community -> Mailing Lists -> Oracle-L -> Re: Contention for undo segments
Tim,
I don't know what application you are running , but buffer busy global CR can happen for many reasons. I suspect some sort of enqueue contention (TX?) or some serialization or hotspots in the objects and that is causing the problem. DO you have the statspack during that time.
You can use the following script to identify the system calls which are responsible for buffer busy events. This will give the sample out put like this..
1 SELECT WH.KCBWHDES MODULE,SW.WHY0 CALLS,SW.WHY2 WAITS,
2 SW.OTHER_WAIT "CAUSED WAITS"
3 FROM x$kcbwh WH, x$kcbsw SW
4 WHERE WH.indx = SW.indx
5 AND SW.OTHER_WAIT > 0
6* ORDER BY SW.OTHER_WAIT
SQL> /
MODULE CALLS WAITS CAUSED WAITS ------------------ ---------- ---------- ------------ ktswh72: ktsbget 2088 0 1 ktswh76: ktsxadd 34682 0 1 ktspfwh8: ktspScan 327 0 1Init1
kdiwh08: kdiixs 3030936 0 1 ktewh25: kteinicnt 285908 0 1 ktbwh00: ktbgtl 491 0 2 ktspswh6: ktspInit 327 0 2Scan
I have a brief discussion about GC waits and the internals in Chapter-8 of OWI book. Just have a loook if you have the book handy.
> As we wait for feedback from Oracle Support, we are trying to find the
> session that is at the head of the logjam. The reason code on which
> these processes are hanging is 130 (P3=130, buffer busy global CR
> request). Our question is, how do you translate the
> V$LOCK_ELEMENT.LOCK_ELEMENT_NAME to a an actual resource and a SID?
>
> (If you have any ideas for us, please cc: sbala_at_Newgen.com if you
> don't mind. Thank you!)
-- Best Regards, K Gopalakrishnan Co-Author: Oracle Wait Interface, Oracle Press 2004 http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/ -- http://www.freelists.org/webpage/oracle-lReceived on Thu Sep 30 2004 - 03:16:40 CDT
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