1

Topic: Library cache lock and cursor: mutex X

Good evening.
There was a basis
All hung on 1 request, thus ASH Viewer shows that there is operation CPU
[spoiler] [img=http://joxi.ru/VrwnWOlUOg3pDA.jpg] [/spoiler]
The request the elementary on reversal to the reference manual, but is a lot of where the used.
[img=http://joxi.ru/8234nZpiJwloZA.jpg]
[img=http://joxi.ru/L21lpybH8Dxegm.jpg]
In the same time if to look in v$session a field event shows waiting cursor: mutex X
Through any time type waitings library cache lock (red on 1 screen) got
Prompt in what side to look. SR we get

2

Re: Library cache lock and cursor: mutex X

feagor;
Recompilations took place to be, packets,  during time ?

3

Re: Library cache lock and cursor: mutex X

Relic Hunter;
Theoretically could, but I think it is improbable. The packet not , would hang at once waiting while it will be released by other sessions

4

Re: Library cache lock and cursor: mutex X

feagor;
And v$session_wait looked, who and for whom waits? Any changes DDL need to be rolled out carefully, in not working hours.

5

Re: Library cache lock and cursor: mutex X

Relic Hunter;
Apparently on 1 picture - waitings any were not - as if all wonderfully works on CPU

wrote:

Any changes DDL need to be rolled out carefully, in not working hours.

I therefore also told that is improbable, be simple up to the end I can not is assured

6

Re: Library cache lock and cursor: mutex X

feagor;
was not?

wrote:

During the same time if to look in v$session a field event shows waiting cursor: mutex X
Through any time type waitings library cache lock (red on 1 screen)

got

7

Re: Library cache lock and cursor: mutex X

Relic Hunter;
, saved with dba_hist_active_sess_history  for the interesting period in the table.
SELECT * FROM ash_020818_2200_0030 t where event = ' cursor: mutex X ' only 500 records, at total in 200 000, blocking_session everywhere the empty

8

Re: Library cache lock and cursor: mutex X

feagor, the information has not enough for the analysis, but from the presented screens it is visible that waitings library cache lock are not connected to a SQL query 26ph5j1gsnz6c.
At 23:11 at you it was launched  which causes 26ph5j1gsnz6c very often, and, about hundred sessions it do simultaneously. Within the first minute after that there is a dark blue strip is in a buffer cache  the table and an index, then calls went only to a buffer cache. And here that happened at 23:57, on pictures it is not visible, it is necessary to select area more close to the right edge that it was possible to look.

9

Re: Library cache lock and cursor: mutex X

Alexander_Ttl;
Like understood a few
From AWR time of analysis of erratic requests simply improbable
failed parse elapsed time 1,106,071.7 153.8

10

Re: Library cache lock and cursor: mutex X

It is solved

11

Re: Library cache lock and cursor: mutex X

Similar situation? https://iusoltsev.wordpress.com/2010/08 … alability/

12

Re: Library cache lock and cursor: mutex X

Alexander_Ttl;
Not absolutely, at us not with BIND the problem was, and with clumsy dynamic requests arriving from external systems