Severe library cache latch contention with DB Control job

From: "Rich Jesse" <rjoralist@xxxxxxxxxxxxxxxxxxxxx>
To: "Oracle L" <oracle-l@xxxxxxxxxxxxx>
Date: Tue, 1 Dec 2009 10:01:06 -0600 (CST)

Hey all,

I've noticed a condition twice in 10 days with our 10.1.0.5.0 DB on AIX
where library cache latch contention was severe.  Each incident I now
believe was caused by the EMD_MAINTENANCE.EXECUTE_EM_DBMS_JOB_PROCS job -- a
leftover from Database Control that I inherited but replaced with Grid
Control over two years ago.  Apparently, I was also supposed to kill this
job, which I now have done.  But two things still bug me.

First, according to Grid Control, this job was launched by SYSMAN but
somehow changed it's session owner to *my* username.  I haven't experimented
with this other than the technique used in exp/imp scripts -- thoughts?  Why
me?

Second, what could this job have done to cause severe library cache latch
contention?  It was bad enough the first time to somehow crash the
DBMS_STATS job that was running with an "ORA-20000: Unable to analyze TABLE
"MYSCHEMA"."MYTABLE", insufficient privileges or does not exist" error.

The job will never run again, but I'm trying to learn as much as I can about
it for future reference.

Thanks!
Rich

p.s.  No references to this job in the list archives, a Google search turned
up a mixed bag of half-complete ideas and a now-non-existent MOS (nee
Metalink) article, and of course not much on MOS, either.

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Severe library cache latch contention with DB Control job

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