Re: RAC waitevent: gc freelist on one node

  • From: "K Gopalakrishnan" <kaygopal@xxxxxxxxx>
  • To: ajayoraclel@xxxxxxxxx
  • Date: Mon, 3 Nov 2008 22:08:29 -0800

Ajay,

Without  version,OS details it is very hard to speculate. GC FREELIST
wait means, basically you are waiting on the LE (Lock Element) during
the lock acquision.  LE works somewhat (in crude terms) like buffer
hash chains and you can query the X$KCLFX (LE Freelist structure) and
see whether the LENGH is close to zero on the offending node.

A quick fix is to restart the node (if the length is zero on the
troubled node and bigger numbers in the other two nodes) just to clear
the mess in the freelist chain.


Best Regards,
K Gopalakrishnan
Co-Author: Oracle Wait Interface, Oracle Press 2004
http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/

Author: Oracle Database 10g RAC Handbook, Oracle Press 2006
http://www.amazon.com/gp/product/007146509X/



On Fri, Oct 31, 2008 at 6:47 AM, Ajay Thotangare <ajayoraclel@xxxxxxxxx> wrote:
> Hi,
> We have having a 3 node RAC and from last few days noticed performance of 1
> of node has degraded. In V$session session of that node, I always see lot of
> sessions waiting on waitevent "gc freelist". I don't see this wait event on
> other 2 nodes where performance is not affected.
> Not sure if this wait event is indicating something. I could not find any
> documentation on this wait event Can somebody please explain me this wait
> event or point me to right document. Does this wait event looks related to
> degraded performance?
> Pls advice.
> --Ajay
>
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