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@xxxxxxxxxxxxxxx>
Sent: Dienstag, 13. Juli 2021 18:19
To: Noveljic Nenad <nenad.noveljic@xxxxxxxxxxxx>; oracle-l@xxxxxxxxxxxxx
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.
@/tmp/ash_wait_chains.sql username||':'||program2||event2
session_type='BACKGROUND' sysdate-1/24 sysdate
%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 11:00:53
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