| SMON taking 80% of CPU [message #60820] |
Mon, 08 March 2004 23:52  |
GDBALP
Messages: 3
Registered: March 2004
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Junior Member |
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Hi all
I have four 9.2.0.3.0 identical (in the structure, not in the content) databases that run on a HPUX 11.11 server.
Since I delete a thousand private synonyms in them, that I replace by public synomym, I have some problems with SMON process,
At startup, and after the db is openned, SMON takes 80% of CPU for about 2 hours. After that, it gets back to a normal behaviour.
Here are the kind of statement that SMON runs, during these two hours (Toad trace session view):
SELECT o.owner#, o.name, o.namespace, o.remoteowner, o.linkname, o.subname,o.dataobj#, o.flags
FROM obj$ o
WHERE o.obj# = :1
and
SELECT obj#, type#, ctime, mtime, stime, status, dataobj#, flags, oid$, spare1, spare2
FROM obj$
WHERE owner# = :1 AND name = :2 AND namespace = :3 AND ( remoteowner = :4 OR remoteowner IS NULL AND :4 IS NULL) AND ( linkname = :5 OR linkname IS NULL AND :5 IS NULL) AND ( subname = :6 OR subname IS NULL AND :6 IS NULL)
Is someone has an idea about this problem?
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| Re: SMON taking 80% of CPU [message #60838 is a reply to message #60820] |
Tue, 09 March 2004 12:26  |
Thiru
Messages: 1089
Registered: May 2002
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Senior Member |
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You will need to trace the SMON process and look at the trace file to find out what its waiting for. In general,Public synonyms are worse than private synonyms when it comes to performance.
Did you try replacing the public synonyms with the private synonyms ? Are you boucing the instance frequently(hence flush the data dictionary cache) ? Are you using a lot of database links ?
-Thiru
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| Re: SMON taking 80% of CPU [message #60866 is a reply to message #60838] |
Wed, 10 March 2004 22:34 |
GDBALP
Messages: 3
Registered: March 2004
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Junior Member |
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Thanks for your answer
I, finally, replaced every public synonyms by the private ones and it is better.
But I found out that, entries relative to the public synonyms, remain in Obj$ table.
Every nights, I shutdown my instances for backup.
I do not use db links.
How do you flush the data dictionary cache?
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| Re: SMON taking 80% of CPU [message #60873 is a reply to message #60866] |
Thu, 11 March 2004 09:00 |
Thiru
Messages: 1089
Registered: May 2002
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Senior Member |
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Glad,its better ,with private synonyms. I meant, when you bounce the instance, the data dictionary cache gets flushed( ofcourse , all other caches get flushed too) and hence it takes a while to warm up the cache,affecting performance negatively. I hope this is not your production DB. Have you thought of hotbackups ?
Also see this thread Public synonyms
to see why you see those entries in sys.obj$
-Thiru
[Updated on: Fri, 18 February 2005 23:32] Report message to a moderator |
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