Re: library cache lock
- From: Fuad Arshad <fuadar@xxxxxxxxx>
- To: Stephen.Barr@xxxxxxxxx, oracle-l@xxxxxxxxxxxxx
- Date: Wed, 12 Jan 2005 13:49:00 -0800 (PST)
Stephan,
i think the situation you are explain ing matches with ours .
i've currently working with oracle but we think we've hot a bug
what version of oracle are you
if 9.2.0.4
look at this bug descriptiopn to see if it matches your scenario
Doc ID:
Note:3443747.8
Subject:
Bug 3443747 - A session can spin holding a library cache latch during fixed
table lookup
Type:
PATCH
Status:
PUBLISHED
Content Type:
TEXT/X-HTML
Creation Date:
30-APR-2004
Last Revision Date:
22-SEP-2004
"Barr, Stephen" <Stephen.Barr@xxxxxxxxx> wrote:
We have a situation where a majority of the sessions in the database are
waiting for "library cache lock".
A simple explain plan against the wh_bills table hangs indefinitely.
READONLY@>select event, count(*)
2 from v$session_wait
3 where state = 'WAITING'
4 group by event
5 order by 2 desc
6 /
EVENT COUNT(*)
---------------------------------------------------------------- ----------
SQL*Net message from client 13
library cache lock 13
rdbms ipc message 9
PX Deq Credit: send blkd 8
PL/SQL lock timer 1
smon timer 1
row cache lock 1
PX Deq: Execute Reply 1
library cache pin 1
pmon timer 1
10 rows selected.
Some of these session have been waiting for days.
The only activity currently happening on the database is a rebuild of the
partitioned indexes on a single table (WH_BILLS). The indexes are being
built by a simple set of statements running in separate sessions which are
actually kicked off via dbms_job and a stored procedure -
Session 1
ALTER INDEX dw_owner.il_bills_001 REBUILD PARTITION p_bills_1998_08
NOPARALLEL NOLOGGING
Session 2
ALTER INDEX dw_owner.il_bills_002 REBUILD PARTITION p_bills_1998_08
NOPARALLEL NOLOGGING
Session 3
ALTER INDEX dw_owner.akl_bills_1 REBUILD PARTITION p_bills_1998_08
NOPARALLEL NOLOGGING
The locking activity produced by this is -
1 select obj.object_type, obj.object_name,l.session_id, l.locked_mode
2 from v$locked_object l,
3 all_objects obj
4* where obj.object_id = l.object_id
READONLY@>/
OBJECT_TYPE OBJECT_NAME SESSION_ID LOCKED_MODE
------------------ ------------------------------ ---------- -----------
TABLE WH_BILLS 151 2
TABLE PARTITION WH_BILLS 151 4
TABLE WH_BILLS 17 2
TABLE PARTITION WH_BILLS 17 4
TABLE WH_BILLS 19 2
TABLE PARTITION WH_BILLS 19 4
TABLE WH_BILLS 44 2
TABLE PARTITION WH_BILLS 44 4
8 rows selected.
Elapsed: 00:00:00.02
READONLY@>
How could this situation arise where we can't even read from the table?
Should the indexes be built like this?
Thanks,
Steve.
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