Re: Oracle user process uses all memory and swap on server
From: Tanel Poder <tanel_at_tanelpoder.com>
Date: Tue, 13 Nov 2012 20:30:50 +0200
Message-ID: <CAMHX9JJhCJkXdFcPqAdvpriD0AZVSfmQGPZkpoAZuE9YjScezA_at_mail.gmail.com>
Tom,
I posted a reply to the forum thread ... basically it's a bug ... As v$pgastat views etc only tell you what Oracle *thinks* is going on, you have to trust OS tools more as they will tell you the reality of what's going on as far as memory usage, disk IO and CPU utilization goes, even if Oracle numbers say otherwise.
Date: Tue, 13 Nov 2012 20:30:50 +0200
Message-ID: <CAMHX9JJhCJkXdFcPqAdvpriD0AZVSfmQGPZkpoAZuE9YjScezA_at_mail.gmail.com>
Tom,
I posted a reply to the forum thread ... basically it's a bug ... As v$pgastat views etc only tell you what Oracle *thinks* is going on, you have to trust OS tools more as they will tell you the reality of what's going on as far as memory usage, disk IO and CPU utilization goes, even if Oracle numbers say otherwise.
https://forums.oracle.com/forums/thread.jspa?messageID=10689303
-- Tanel Poder Blog - http://blog.tanelpoder.com App - http://voic.ee -- *Tanel Poder* Enkitec Europe +372 56 956 181 http://www.enkitec.com/ Expert Oracle Exadata book: http://www.apress.com/9781430233923 On Mon, Nov 12, 2012 at 5:04 PM, Tom Dale <tom.dale_at_fivium.co.uk> wrote:Received on Tue Nov 13 2012 - 19:30:50 CET
> Hi Oracle-l,
> When I run a simple select on one 160mb clob, the oracle foreground process
> uses all memory, swap then hangs the server.
>
> This happens on red hat 4.5, 5.7 and OEL 6.3 Tested
> Oracle 10.2.0.4 and 11.2.0.3.4 Tested
>
> Oracle Support :
> -----
> What is happening is that single block reads are being done which
> presumably also takes up more and more buffer space, as well
> as making for very poor performance. This will give the appearance of a
> hang.
> -----
>
> I do not think that is the case!!
>
> My question is :
>
> How can the Oracle OS user process consume all the memory when the the SGA
> is small and v$pgastat shows a small maxpga?
>
> Test script is on OTN
>
> https://forums.oracle.com/forums/thread.jspa?threadID=2463164&tstart=0
>
> Bit more info...
>
> When I run an OS strace and a 10046 trace, after the last traced event in
> the oracle session trace, the process strace continues with
>
> brk(0x60013000) = 0x5ffef000
> mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
> = 0x2b9e775b5000
> brk(0x60013000) = 0x5ffef000
> mmap(NULL, 1048576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0)
> = 0x2b9e776b5000
> ...
> Repeating
> ...
>
> Any answers would enlightening!
>
> Thanks,
> Tom
>
>
> --
> http://www.freelists.org/webpage/oracle-l
>
>
>
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