John,
Thanks. I forgot all about LAST_DDL_TIME. Of course this hasn't happened
again, but at least I've got a strategy if/when it does.
Henry
-Original Message-
John Kanagaraj
Sent: Monday, July 07, 2003 3:10 PM
To: Multiple recipients of list ORACLE-L
Henry,
These locks should normally occur when dependent objects needs to be
compiled (internally by the kernel or externally by scripts) on account of
invalidations. This problem is magnified in large ERP packages which
exhibits lots of dependencies and objects. Since you mention that this is
just moving into Production, you are probably experiencing a lot of
last-minute changes that are causing this. The only way of controlling this
is by scheduling changes to off-hours (even in Dev/UA), and most certainly
in Production. Sort DBA_OBJECTS by LAST_DDL_TIME to check which objects
changed. You could also write an ON DDL trigger to log details of who
modified which object from where and at what time.
You could look at ML Note 62143.1 'Understanding and Tuning the Shared Pool'
to understand the intricacies of the Shared pool.
If this is not due to invalidations, then it could be on account of a number
of shared pool related bugs (don't know what version you are on).
John Kanagaraj
Oracle Applications DBA
DBSoft Inc
(W): 408-970-7002
Great, uplifting music - http://www.klove.com
** The opinions and statements above are entirely my own and not those of my
employer or clients **
-Original Message-
From: Henry Poras [mailto:[EMAIL PROTECTED]
Sent: Thursday, July 03, 2003 9:06 AM
To: Multiple recipients of list ORACLE-L
Subject: wierd wait event - library cache load lock
We have a PeopleSoft system (Finanacials) that is just moving into
production. Some of the conversion and data entry stuff was
running slowly
so I peaked at our system and session wait events (as well as
looking at
some recent history with statspack). There was a huge amount
of time_waited
for 'library cache load lock'. Never came across this one
before. According
to the Docs, it is a lock used to load an object into the
library cache (you
don't want the same object loaded more than once). I am
trying to find more
information so I can debug this. Of course the problem isn't
there today
(other modules are being worked on. Maybe that is why).
Just trying to be ready when/if this happens again. I'm
thinking a 10046
trace might give me some object information about what is being
loaded/locked. Metalink suggests taking a systemstate dump
(though they seem
to mix up 'library cache lock' with 'library cache load
lock'. Don't know if
the same tracking techniques work on both.).
Anybody else see this before? Suggestions on what to do if it shows up
again?
Thanks.
Henry
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