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shared pool latch time out exceeding 40% HELP!!!

From: Kunihito Ishibashi <ishi_at_future.co.jp>
Date: 30 Apr 1999 19:58:41 GMT
Message-ID: <01be9342$bec18230$6a96050a@fsrv6>


upon doing further investigation of the oracle db problem that we wereexperiencing
(cpu usage exceeding 100%), we discovered that the db isnot successfully
obtaining the "latch" necessary to perform a transaction
(in trying to obtain the latch, oracle goes through an excessive number
ofloops).

with the spin count set to 2,000 and using oracle's estat/bstat tool, we obtained the below results. according to oracle's documentation, the xxx latch time out
statistics should not exceed 1%. however, in our tests,the shared pool latch time out percentage
reached approximately 40% (out of10 million transaction, 3.9 million of the transactions failed).
referring once again to oracle's documentation, it is noted that increasing the shared pool
size to 300000000 its current value should improve performance
(in other words, reduce the shared pool latch time out percentage to a more
reasonable percentage).
however, making such changes did not yield any improvement.

we are wondering whether this is a problem with the HP-UX B.11.00 or with oracle8.0.5.1.0.

any feedback is appreciated. thank you...

xxx LATCH TIMEOUT (oracle's estat/bstat): ROW_CACHE_OBJECT 5%

SHARD_POOL               40%
LIBRARY_CACHE          12%
REDO_ALLOCATION   0.09%
REDO_COPY              0.05%

SERVER SPEC:
HP-UX k580a B.11.00 E 9000/800 (th) 32bit CPU PA-8200 x 6
MEMORY 2GB

DISK         EMC SYMMETRIX MODEL3430 (5GB MEMORY/800GB DISK)
                EMC POWERPATH RELEASE 1.3
ORACLE RELEASE 8.0.5.1.0 Received on Fri Apr 30 1999 - 14:58:41 CDT

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