No blocking session for wait event: 'Library cache pin'
- From: Sanjeev M <sanjeevorcle@xxxxxxxxx>
- To: ORACLE-L <oracle-l@xxxxxxxxxxxxx>
- Date: Tue, 2 Aug 2011 11:19:34 -0700
Environment: 2 node RAC on OEL 5
Grid Home : 11.2.0.2
RDBMS Home: 11.1.0.7.7
On our database, Session was waiting most of the time on 'library cache pin'
wait - for a decent amount like a minute or more before toggling to another
wait event db file sequential read and back to this wait.
Could it be a bug that the blocker session is not showing up?
select p1raw,p1text,event,sid from v$session where sid=1710;
P1RAW
P1TEXT
EVENT SID
----------------
----------------------------------------------------------------
---------------------------------------------------------------- ----------
0000000356213B10 handle
address library cache
pin 1710
select * from x$kglpn where KGLPNHDL='000000032FA9B7A0';
no rows selected <=== Expected to see some info here regading object,
lock mode (Either null/shared or exclusive) however no output!!!
Also checked for other handle addresses from gv$session to see if it
possibly is having some kind of dependancy:
select inst_id,p1raw,count(1) from gv$session where event='library cache
pin' group by inst_id,p1raw;
INST_ID P1RAW COUNT(1)
---------- ---------------- ----------
1 000000032FA9B7A0 1
1 0000000356213B10 1
select * from x$kglpn where KGLPNHDL='000000032FA9B7A0';
no rows selected <=== Expected to see some info here regading object,
lock mode (Either null/shared or exclusive) however no output!!!
Also tried gv$ges_blocking_enqueue however output does not show anything
related to *"lib pin -- Nx Gx"*
'WAI INST_ID SPID RESOURCE_NAME1
---- ---------- ---------- ------------------------------
Wait 1 10838 [0x75daf18b][0x4c05b769],[NB]
Wait 2 17532 [0x19][0x2],[RS]
Wait 2 0 [0x8c0][0x10000],[BL]
Blkr 1 10132 [0x19][0x2],[RS]
Blkr 2 17508 [0x1][0x0],[PW]
Ran tanel poder's snapper while this was happening and it says session on
CPU:
@snapper ash=sql_id+event+wait_class+p1+p2+p3 5 1 1710
Sampling SID 1710 with interval 5 seconds, taking 1 snapshots...
-- Session Snapper v3.14 by Tanel Poder @ E2SN ( http://tech.e2sn.com )
--------------------------------------------------------------------------------------------------------------------------------
Active% | SQL_ID | EVENT | WAIT_CLASS |
P1 | P2 | P3
--------------------------------------------------------------------------------------------------------------------------------
* 100% | 10za9fj1va0kd | ON CPU | ON CPU
| | |*
-- End of ASH snap 1, end=2011-08-02 11:00:58, seconds=5, samples_taken=42
PL/SQL procedure successfully completed.
*SQL statement that was being run for this session was:*
select msi.inventory_item_id from mtl_parameters mp,
mtl_system_items msi,
mtl_system_items_interface msii where
msii.transaction_id = :transaction_id_bind and
msii.set_process_id = :set_id_bind2 *and rownum = 1
* and msi.organization_id = mp.organization_id
and msi.segment1 = msii.segment1
Plan hash value: 904999408
----------------------------------------------------------------------------------------------------------------
| Id | Operation | Name |
Rows | Bytes | Cost (%CPU)| Time |
----------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT |
| | | 342 (100)| |
|* 1 | COUNT STOPKEY |
| | | | |
| 2 | NESTED LOOPS | |
21 | 882 | 342 (1)| 00:00:05 |
| 3 | NESTED LOOPS | |
21 | 798 | 342 (1)| 00:00:05 |
| 4 | TABLE ACCESS FULL | MTL_SYSTEM_ITEMS_B |
12245 | 191K| 342 (1)| 00:00:05 |
|* 5 | TABLE ACCESS BY INDEX ROWID| MTL_SYSTEM_ITEMS_INTERFACE |
1 | 22 | 0 (0)| |
|* 6 | INDEX RANGE SCAN | MTL_SYSTEM_ITEMS_INTERFACE_N6 |
1 | | 0 (0)| |
|* 7 | INDEX UNIQUE SCAN | MTL_PARAMETERS_U1 |
1 | 4 | 0 (0)| |
----------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter(ROWNUM=1)
5 - filter(("MSII"."SET_PROCESS_ID"=:SET_ID_BIND2 AND
"MSI"."SEGMENT1"="MSII"."SEGMENT1"))
6 - access("MSII"."TRANSACTION_ID"=:TRANSACTION_ID_BIND)
7 - access("MSI"."ORGANIZATION_ID"="MP"."ORGANIZATION_ID")
Any pointers or help much appreciated.
Thanks,
Sanjeev.
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