RE: [EXTERNAL] RE: AQ process waiting on "library cache: mutex X"
Date: Wed, 14 Jul 2021 14:42:52 +0000
Message-ID: <CH0PR14MB5012464C8356E6DB5C233049E0139_at_CH0PR14MB5012.namprd14.prod.outlook.com>
Thank you, Nenad. Please see the output from ASHTOP. The highlighted lines are Qnnn processes.
_at_ashtop session_id,username,sql_id,in_parse,sql_opname,top_level_call_name session_type='BACKGROUND' sysdate-2/24 sysdate
Total Distinct Distinct
Seconds AAS %This SESSION_ID USERNAME SQL_ID I SQL_OPNAME TOP_LEVEL_CALL_NAME FIRST_SEEN LAST_SEEN Execs Seen Tstamps
--------- ------- ------- ---------- --------------- ------------- - -------------------- ------------------------------ ------------------- ------------------- ---------- --------
7103 1.0 54% | 28 SYS N VERSION2 2021-07-14 07:36:23 2021-07-14 09:36:22 1 7103
5820 .8 44% | 607 SYS N VERSION2 2021-07-14 07:36:23 2021-07-14 09:36:22 1 5820
91 .0 1% | 1066 SYS N LOGOFF 2021-07-14 07:36:57 2021-07-14 09:35:56 1 91
78 .0 1% | 452 SYS N 2021-07-14 07:41:21 2021-07-14 09:35:06 1 78
33 .0 0% | 451 SYS N 2021-07-14 07:36:35 2021-07-14 09:35:00 1 33
28 .0 0% | 1 SYS N 2021-07-14 07:41:49 2021-07-14 09:32:59 1 28
20 .0 0% | 602 SYS N 2021-07-14 08:02:00 2021-07-14 09:30:53 1 20
11 .0 0% | 302 SYS N 2021-07-14 07:38:57 2021-07-14 09:28:37 1 11
6 .0 0% | 157 SYS N VERSION2 2021-07-14 07:37:57 2021-07-14 09:35:00 1 6
5 .0 0% | 1052 SYS N 2021-07-14 07:49:10 2021-07-14 09:28:45 1 5
4 .0 0% | 301 SYS N 2021-07-14 07:58:03 2021-07-14 09:26:02 1 4
2 .0 0% | 21 SYS bunssq950snhf N INSERT VERSION2 2021-07-14 09:00:33 2021-07-14 09:00:34 1 2
2 .0 0% | 903 SYS N 2021-07-14 07:50:09 2021-07-14 08:27:55 1 2
2 .0 0% | 1053 SYS N VERSION2 2021-07-14 08:06:16 2021-07-14 08:42:26 1 2
1 .0 0% | 7 SYS N VERSION2 2021-07-14 07:52:24 2021-07-14 07:52:24 1 1
15 rows selected.
I will try to get pstack of the above two processes. I don't have access to the oracle account, I will have to ask someone to do it for me.
Thank you!
From: Noveljic Nenad <nenad.noveljic_at_vontobel.com>
Sent: Wednesday, July 14, 2021 1:36 AM
To: Hameed, Amir <amir.hameed_at_sleepnumber.com>; oracle-l_at_freelists.org
Subject: RE: [EXTERNAL] RE: AQ process waiting on "library cache: mutex X"
Hi Hameed,
Actually AQ waiters were at least partly blocked by AQ processes spinning on CPUs:
1% 40 0 1 -> SYS:(Qnnn) library cache: mutex X -> SYS:(Qnnn) ON CPU 2021-07-13 10:14:02 2021-07-13 11:11:55
Any AQ processes are spending much more time on CPU anyway, so I would focus on them.
Could you include the following columns in ashtop output: in_parse,sql_opname,top_level_call_name,sql_id ?
Could you take a couple of "pstack PID" ?
How many AQs are spinning on CPU?
You can use the following filter condition for AQ processes "program2 like '%Qnn%'"
Best regards,
Nenad
From: Hameed, Amir <amir.hameed_at_sleepnumber.com<mailto:amir.hameed_at_sleepnumber.com>>
Sent: Dienstag, 13. Juli 2021 18:19
To: Noveljic Nenad <nenad.noveljic_at_vontobel.com<mailto:nenad.noveljic_at_vontobel.com>>; oracle-l_at_freelists.org<mailto:oracle-l_at_freelists.org>
Subject: RE: [EXTERNAL] RE: AQ process waiting on "library cache: mutex X"
Thanks Nenad. In my case, the USERNAME is NULL, and therefore, I used the following syntax. However, the output doesn't show any blocker unless I am reading it incorrectly.
%This SECONDS AAS #Blkrs WAIT_CHAIN FIRST_SEEN LAST_SEEN ------ ---------- ---------- ------ -------------------------------------------------------------------------------------------------------------- ------------------- ------------------- 90% 6071 1.7 4 -> SYS:(Qnnn) ON CPU 2021-07-13 10:13:37 2021-07-13 11:13:35 4% 271 .1 3 -> SYS:(Qnnn) library cache: mutex X 2021-07-13 10:13:36 2021-07-13 11:13:32 3% 221 .1 1 -> SYS:(LGWR) log file parallel write 2021-07-13 10:16:05 2021-07-13 11:13:24 1% 53 0 2 -> SYS:(Mnnn) ON CPU 2021-07-13 10:13:47 2021-07-13 11:13:28 1% 40 0 1 -> SYS:(Qnnn) library cache: mutex X -> SYS:(Qnnn) ON CPU 2021-07-13 10:14:02 2021-07-13 11:11:55 0% 23 0 1 -> SYS:(DIAn) ON CPU 2021-07-13 10:16:10 2021-07-13 11:11:57 0% 18 0 1 -> SYS:(DBWn) db file parallel write 2021-07-13 10:16:14 2021-07-13 11:12:17 0% 13 0 1 -> SYS:(LGWR) ON CPU 2021-07-13 10:19:02 2021-07-13 11:12:32 0% 9 0 1 -> SYS:(PSPn) ON CPU 2021-07-13 10:20:06 2021-07-13 11:12:26 0% 7 0 1 -> SYS:(DBWn) ON CPU 2021-07-13 10:16:02 2021-07-13 11:12:23 0% 6 0 1 -> SYS:(CKPT) control file parallel write 2021-07-13 10:23:02 2021-07-13 11:00:56 0% 5 0 5 -> SYS:(Mnnn) Disk file operations I/O 2021-07-13 10:31:16 2021-07-13 11:11:19 0% 4 0 1 -> SYS:(CKPT) control file sequential read 2021-07-13 10:22:56 2021-07-13 10:32:46 0% 4 0 1 -> SYS:(CJQn) os thread startup 2021-07-13 10:20:00 2021-07-13 11:12:26 0% 4 0 2 -> SYS:(Qnnn) Streams AQ: deallocate messages from Streams Pool 2021-07-13 10:16:39 2021-07-13 11:04:56 0% 3 0 1 -> SYS:(DBWn) db file async I/O submit 2021-07-13 10:16:05 2021-07-13 10:57:48 0% 2 0 1 -> SYS:(Mnnn) db file sequential read 2021-07-13 11:00:27 2021-07-13 11:00:28 0% 2 0 1 -> SYS:(CJQn) ON CPU 2021-07-13 10:41:01 2021-07-13 11:05:37 0% 2 0 1 -> SYS:(DBRM) ON CPU 2021-07-13 10:46:10 2021-07-13 11:10:00 0% 2 0 1 -> SYS:(SMON) ON CPU 2021-07-13 10:22:39 2021-07-13 10:32:02 0% 2 0 1 -> SYS:(LGWR) LGWR wait for redo copy -> APPS:(JDBC Thin Client) ON CPU 2021-07-13 10:27:09 2021-07-13 10:27:12 0% 1 0 1 -> SYS:(MMON) ON CPU 2021-07-13 10:17:21 2021-07-13 10:17:21 0% 1 0 1 -> SYS:(Mnnn) direct path write 2021-07-13 11:00:26 2021-07-13 11:00:26 0% 1 0 1 -> SYS:(Qnnn) db file sequential read 2021-07-13 10:29:15 2021-07-13 10:29:15 0% 1 0 1 -> SYS:(Mnnn) control file sequential read 2021-07-13 11:00:25 2021-07-13 11:00:25 0% 1 0 1 -> SYS:(QMNC) ON CPU 2021-07-13 11:08:45 2021-07-13 11:08:45 0% 1 0 1 -> SYS:(LGWR) LGWR wait for redo copy -> APPS:(frmweb) ON CPU 2021-07-13 10:32:02 2021-07-13 10:32:02 0% 1 0 1 -> SYS:(CKPT) ON CPU 2021-07-13 11:00:53 2021-07-13 11:00:53Please consider the environment before printing this e-mail. Bitte denken Sie an die Umwelt, bevor Sie dieses E-Mail drucken.
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