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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Latch Contention
John,
We made no changes this past week as this is month end close. There were a few concurrent jobs but nothing that really stood out. Most users were trying to access Apps via ADI. There used to be an issue with ADI 3.x and latch free waits. We had upgraded to ADI 7.x and that problem with latch free waits went away. I know what sessions were waiting on these latches. But there was no one particular similarity standing out among those either.
Thanks,
Venu
> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org [SMTP:oracle-l-bounce_at_freelists.org] On Behalf Of John Kanagaraj
> Sent: Monday, March 01, 2004 6:20 PM
> To: 'oracle-l_at_freelists.org'
> Subject: RE: Latch Contention
>
> Venu,
>
> Were you able to determine which and how many Concurrent requests were
> running at that time, and what changes if any were done for these programs?
> (the changes may be have been in the past, but manifest themseleves now as
> some programs run only during the monthend). I had a very interesting and
> similar situation where a scheduled cron job came in occassionally to
> generate 'GRANT SELECT' on all objects in all schemas to a read-only account
> and then run the resulting SQLs several times a day. This generates
> thousands of tiny (in comparison) SQLs, each of which had to be parsed, and
> modify objects and thus invalidating lib cache/dd cache and cluttered up
> shared pool. Shared pool and Lib cache latches were through the roof. I used
> V$SESSION_WAIT to determine which sessions were waiting and thus determined
> what was happening... The fix was to stop running this during peak hours and
> change it to GRANT SELECT on only new objects...
>
> John Kanagaraj <><
> DB Soft Inc
> Phone: 408-970-7002 (W)
>
> Listen to great, commercial-free christian music 24x7x365 at
> http://www.klove.com
>
> ** The opinions and facts contained in this message are entirely mine and do
> not reflect those of my employer or customers **
>
> -----Original Message-----
> From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org]
> On Behalf Of Potluri, Venu (CT Appl Suppt)
> Sent: Monday, March 01, 2004 2:55 PM
> To: oracle-l_at_freelists.org
> Subject: Latch Contention
>
>
> Today we had problems with latch contention in our production Oracle Apps
> database. I saw lots of latch free waits, of the cache buffer chains and
> library cache variety. I looked for the most resource intensive sessions.
> But nothing stood out. Finally I flushed the shared pool (Cary Millsap is
> going to cringe at this time........). That cleared all the latch free waits
> and users reported better performance. Didn't want to flush the shared pool
> but had to do it due to month end close processing that was getting severly
> bogged down. I still haven't found the root cause. My question is where to
> look for the root cause next time.
> Here are some stats I gathered while the problem occurred.
>
>
> NAME GETS Miss % Spin % IGETS
> IMISSES
> ------------------------- ------------ ------- ------- ------------
> ---------
> intra txn parallel recove 0 .00 .00 0
> 0
> ry
> parallel txn reco latch 0 .00 .00 0
> 0
> address list 1 .00 .00 0
> 0
> mostly latch-free SCN 2 .00 .00 0
> 0
> NLS data objects 2 .00 .00 0
> 0
> Direct I/O Adaptor 2 .00 .00 0
> 0
> message pool operations p 3 .00 .00 0
> 0
> arent latch
> begin backup scn array 37 .00 .00 0
> 0
> X$KSFQP 39 .00 .00 0
> 0
> archive process latch 167 .00 .00 0
> 0
> file number translation t 285 .00 .00 0>
> 0
> able
> ktm global data 300 .00 .00 0
> 0
> archive control 927 .00 .00 0
> 0
> longop free list 1,160 .00 .00 0
> 0
> NAME GETS Miss % Spin % IGETS
> IMISSES
> ------------------------- ------------ ------- ------- ------------
> ---------
> device information 1,710 .00 .00 0
> 0
> kwqit: protect wakeup tim 2,811 .00 .00 0
> 0
> dictionary lookup 3,250 .00 .00 0
> 0
> global tx free list 3,763 .00 .00 0
> 0
> sort extent pool 4,086 .00 .00 0
> 0
> loader state object freel 6,103 .00 .00 0
> 0
> ist
> ncodef allocation latch 9,642 .00 .00 0
> 0
> job_queue_processes param 9,642 .00 .00 0
> 0
> eter latch
> hash table modification l 0 .00 .00 22,991
> 0
> atch
> session switching 24,272 .00 .00 0
> 0
> i/o slave adaptor 0 .00 .00 36,912
> 0
> vecio buf des 0 .00 .00 36,912
> 0
> library cache load lock 38,888 .04 100.00 0
> 0
> NAME GETS Miss % Spin % IGETS
> IMISSES
> ------------------------- ------------ ------- ------- ------------
> ---------
> event group latch 40,868 .00 .00 0
> 0
> transaction branch alloca 53,467 .00 .00 0
> 0
> tion
> process group creation 80,972 .00 .00 0
> 0
> channel handle pool latch 80,981 .00 .00 0
> 0
> process allocation 40,868 .04 .00 40,863
> .01223601
> channel operations parent 121,890 .00 .00 0
> 0
> latch
> global tx hash mapping 158,890 .00 .00 0
> 0
> user lock 180,484 .01 68.42 0
> 0
> Token Manager 181,487 .00 100.00 36,912
> 0
> sequence cache 341,190 .01 89.66 0
> 0
> active checkpoint queue l 695,343 .00 .00 0
> 0
> atch
> list of block allocation 1,130,452 .00 100.00 0
> 0
> dml lock allocation 1,322,672 .00 100.00 0
> 0
> redo writing 1,598,340 .08 99.10 0
> 0
> global transaction 2,039,041 .00 .00 0
> 0
> NAME GETS Miss % Spin % IGETS
> IMISSES
> ------------------------- ------------ ------- ------- ------------
> ---------
> transaction allocation 2,532,521 .00 100.00 0
> 0
> undo global data 2,744,812 .00 100.00 0
> 0
> enqueue hash chains 3,303,961 .00 94.44 0
> 0
> enqueues 3,814,510 .01 99.50 0
> 0
> session allocation 4,803,687 .04 92.49 0
> 0
> messages 5,014,273 .06 99.27 0
> 0
> multiblock read objects 10,086,892 .02 99.42 2
> 0
> session idle bit 13,586,255 .00 100.00 0
> 0
> row cache objects 16,937,164 .08 99.75 89
> 1.1235955
> checkpoint queue latch 23,051,771 .00 67.45 0
> 0
> redo copy 13,680 .00 .00 36,266,260
> .00756626
> redo allocation 36,522,674 .01 99.87 0
> 0
> cache buffer handles 82,954,716 .32 99.93 0
> 0
> cache buffers lru chain 36,022,870 .14 96.82 79,027,986>
> .16287268
> shared pool 379,947,867 .16 98.51 0
> 0
> latch wait list 317,618,315 5.94 99.76 297,982,053
> 5.0251922
> library cache ############ 293.06 94.87 819,140
> 3.7733477
> cache buffers chains ############ .16 99.78 107,818,804
> .02991315
>
>
>
>
> spin sl01 sl02 sl03 sl04 sl05
> NAME GETS Miss % sl06 sl07 sl08 sl09 sl10 sl11
> ------------------ ------------ ------ ------ ----- ----- ----- ----- -----
> cache buffers chai ############ 0.2 99.8 0.2 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> library cache ############ ##### 94.9 4.0 0.7 0.4 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> shared pool 379,948,308 0.2 98.5 0.3 0.7 0.4 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> latch wait list 317,630,086 5.9 99.8 0.2 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> cache buffer handl 82,954,716 0.3 99.9 0.1 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> redo allocation 36,522,674 0.0 99.9 0.1 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> cache buffers lru 36,022,877 0.1 96.8 3.2 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> checkpoint queue l 23,051,900 0.0 67.4 32.6 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> row cache objects 16,937,179 0.1 99.8 0.2 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> session idle bit 13,586,307 0.0 100.0 0.0 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> spin sl01 sl02 sl03 sl04 sl05
> NAME GETS Miss % sl06 sl07 sl08 sl09 sl10 sl11
> ------------------ ------------ ------ ------ ----- ----- ----- ----- -----
> multiblock read ob 10,086,892 0.0 99.4 0.6 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> messages 5,014,290 0.1 99.3 0.7 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> session allocation 4,803,691 0.0 92.5 7.3 0.1 0.1 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> enqueues 3,814,532 0.0 99.5 0.5 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> enqueue hash chain 3,303,974 0.0 94.4 5.6 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> undo global data 2,744,812 0.0 100.0 0.0 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> transaction alloca 2,532,523 0.0 100.0 0.0 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> redo writing 1,598,345 0.1 99.1 0.9 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> dml lock allocatio 1,322,672 0.0 100.0 0.0 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> list of block allo 1,130,452 0.0 100.0 0.0 0.0 0.0 0.0 0.0 >
> 0.0 0.0 0.0 0.0 0.0 0.0
> spin sl01 sl02 sl03 sl04 sl05
> NAME GETS Miss % sl06 sl07 sl08 sl09 sl10 sl11
> ------------------ ------------ ------ ------ ----- ----- ----- ----- -----
> sequence cache 341,190 0.0 89.7 10.3 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> Token Manager 181,487 0.0 100.0 0.0 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> user lock 180,484 0.0 68.4 26.3 5.3 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> process allocation 40,868 0.0 0.0 93.3 6.7 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
> library cache load 38,888 0.0 100.0 0.0 0.0 0.0 0.0 0.0
> 0.0 0.0 0.0 0.0 0.0 0.0
>
>
> CHILD# ROUND(SLEEPS/GETS*100,2) RATIO
> --------- ------------------------ ---------
> 12 0 100
> 11 0 100
> 10 0 100
> 9 0 100
> 8 0 100
> 7 0 100
> 6 0 100
> 5 0 100
> 4 0 100
> 3 0 100
> 2 0 100
> 1 0 100
>
>
>
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