Thanks, Jonathan.
Last week the MOS search on SQL_ID frccccnh76gtx didn't return anything, now it
does.
Best regards,
Nenad
https://nenadnoveljic.com/blog/
-----Original Message-----
From: Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx>
Sent: Samstag, 22. Februar 2020 21:16
To: ORACLE-L (oracle-l@xxxxxxxxxxxxx) <oracle-l@xxxxxxxxxxxxx>; Noveljic Nenad
<nenad.noveljic@xxxxxxxxxxxx>
Subject: Re: control file i/o buffer allocations
Known bug:
30098251 : WNNN PROCCESSES CREATE AN EXCESSIVE NUMBER OF OPEN CURSOR
Fixed in 20.1
There are a number of patches to older versions.
Regards
Jonathan Lewis
________________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx <oracle-l-bounce@xxxxxxxxxxxxx> on behalf
of Noveljic Nenad <nenad.noveljic@xxxxxxxxxxxx>
Sent: 21 February 2020 15:37
To: ORACLE-L (oracle-l@xxxxxxxxxxxxx)
Subject: control file i/o buffer allocations
I've been observing unusually large process memory allocations for space
manager slaves on 18c, for example:
SQL>
select program,module,action,event from v$session where sid = 712 ;
PROGRAM MODULE
ACTION
EVENT
------------------------------------------------
----------------------------------------------------------------
----------------------------------------------------------------
----------------------------------------------------------------
oracle@SERVER (W007) KTSJ
KTSJ Slave
Space Manager: slave idle wait
As we can see below, a single space manager process has allocated ~144MB for
'control file i/o buffer':
select category,name,heap_name,bytes,allocation_count
from v$process_memory_detail where name='control file i/o buffer' ;
CATEGORY NAME HEAP_NAME BYTES
ALLOCATION_COUNT
--------------- -------------------------- --------------- ----------
----------------
SQL control file i/o buffer kxs-heap-w 144775944
459
Further, it had 459 allocations which roughly matches the number of open
cursors on v$datafile query that aren't getting closed:
select sql_id,sql_text,cursor_type,count(*) from v$open_cursor
where sid = 712 group by sql_id,sql_text,cursor_type order by count(*) desc ;
SQL_ID SQL_TEXT
CURSOR_TYPE COUNT(*)
------------- ------------------------------------------------------------
---------------------------------------------------------------- ----------
frccccnh76gtx select rfile# from v$datafile where file# = :1
OPEN-RECURSIVE 461
2360z2hxanh3w select nvl(con_id, 0), lobtsn, lobrdba, lobobjid from x$lobs
SESSION CURSOR CACHED 1
Any ideas on what might have caused this allocation? Is it really related to
open cursors? Why aren't the cursors getting closed? How to release the memory
back without restarting these processes? How to prevent this from happening?
How to reproduce it at will?
Thanks in advance,
Nenad
https://nenadnoveljic.com/blog/
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