@Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx> I'm a little confused.
I included outputs EXCEPT for the one you asked for that was a join between
gv$lock and gv$session.
Those sids are in most of the previous outputs I sent?
But yes, those 3 are database scheduler jobs.
Thanks,
Chris
On Wed, Apr 1, 2020 at 1:06 PM Jonathan Lewis <jonathan@xxxxxxxxxxxxxxxxxx>
wrote:
If you look at rows 23,51.84 there are your three long-time blockers
INST_ID ADDR KADDR SID TYPE
ID1 ID2 LMODE REQUEST CTIME BLOCK CON_ID
1 0000002AFF0ABF18 0000002AFF0ABF98 6956 TX
2555927 56779000 6 0 12960 1 0
3 0000002AFF40C238 0000002AFF40C2B8 4871 TX
92864542 2439787 6 0 29356 1 0
3 0000002AFEC73E18 0000002AFEC73E98 3499 TX
93782036 2876653 6 0 39862 1 0
So now you have to work out why instance 1, sid 6956; 3/4871, and 3/3499
aren't showing up on your other reporting mechanisms.
It's also a little odd that they acquired their locks a long time ago -
much longer than the current waiters started waiting.
Are they background processes (like jobs, perhaps) that you omit from your
query ?
Regards
Jonathan Lewis
________________________________________
From: Chris Taylor <christopherdtaylor1994@xxxxxxxxx>
Sent: 01 April 2020 17:43
To: Jonathan Lewis
Cc: Oracle L
Subject: Re: Weird Situation (12.1.0.2 Exadata Cloud @ Customer) -
Blocking locks with no blocker
Attached are the results for that.
Chris
On Wed, Apr 1, 2020 at 12:15 PM Jonathan Lewis <
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx>> wrote:
I had intended the replies to go to Oracle-l as well - so copying them
back in.
The query against gv$session join gv$lock shows that there are no sessions
holding the TX locks that are being waited for - and the waits are mode 6.
Could you just do a listing of
select * from gv$lock where type = 'TX' order by id1, id2, lmode;
Just in case there's a way in which a lock could be held for a session
that doesn't exist.
Regards
Jonathan Lewis
________________________________________
From: Chris Taylor <christopherdtaylor1994@xxxxxxxxx<mailto:
christopherdtaylor1994@xxxxxxxxx>>
Sent: 01 April 2020 17:04
To: Jonathan Lewis
Subject: Re: Weird Situation (12.1.0.2 Exadata Cloud @ Customer) -
Blocking locks with no blocker
Also have this query which the output is a bit nicer:
SELECT /*+ RULE */
k.inst_id,
ss.username,
DECODE (request, 0, 'Holder: ', ' Waiter: ') || k.sid
sess,
ss.sql_id,
k.id1,
k.id2,
k.lmode,
k.request,
k.TYPE,
SS.LAST_CALL_ET,
SS.SECONDS_IN_WAIT,
SS.SERIAL#,
SS.MACHINE,
SS.EVENT,
ss.status,
P.SPID,
CASE
WHEN request > 0
THEN
CHR (BITAND (p1, -16777216) / 16777215)
|| CHR (BITAND (p1, 16711680) / 65535)
ELSE
NULL
END
"Name",
CASE WHEN request > 0 THEN (BITAND (p1, 65535)) ELSE NULL END
"Mode"
FROM GV$LOCK k, gv$session ss, gv$process p
WHERE (k.id1, k.id2, k.TYPE) IN (SELECT ll.id1, ll.id2, ll.TYPE
FROM GV$LOCK ll
WHERE request > 0)
AND k.sid = ss.sid
AND K.INST_ID = SS.INST_ID
AND ss.paddr = p.addr
AND SS.INST_ID = P.INST_ID
ORDER BY id1, request;
On Wed, Apr 1, 2020 at 11:56 AM Jonathan Lewis <
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx>>> wrote:
But then I realised that I'd forgotten to change the name of the table
owner and table
Regards
Jonathan Lewis
________________________________________
From: Chris Taylor <christopherdtaylor1994@xxxxxxxxx<mailto:
christopherdtaylor1994@xxxxxxxxx><mailto:christopherdtaylor1994@xxxxxxxxx
<mailto:christopherdtaylor1994@xxxxxxxxx>>>
Sent: 01 April 2020 16:47
To: Jonathan Lewis
Subject: Re: Weird Situation (12.1.0.2 Exadata Cloud @ Customer) -
Blocking locks with no blocker
Here's the output for this modified version of what you asked for. Wasn't
sure what you'd like to see from gv$session
select l.*, v.inst_id, v.sid, v.serial#,v.program, v.event,
v.wait_time_micro/1000000 as wait_time_secs, v.wait_class
from gv$lock l, gv$session v
where v.inst_id = l.inst_id
and v.sid = l.sid
and v.type != 'BACKGROUND'
and v.wait_time_micro/1000000 > 30
and v.wait_class != 'Idle'
Order by l.sid, l.type
/
On Wed, Apr 1, 2020 at 11:28 AM Jonathan Lewis <
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx>><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx>>>> wrote:
What was the query you ran to generate the output ?
Can you run a query that joins v$session for the waiting sessions with
v$lock on SID.
Order by sid, type
Break on sid skip 1
Looking at the view dba_blockers it identifies blockers by BLOCK = 1.
I don't have a RAC with me to check but ALL held locks (v$lock) in RAC are
flagged with BLOCK = 2 (as "potential blockers") and MAY NOT go to 1 when
they are blocking cross instance. So the problem may be the definition of
dba_blockers - but I'd have to run up a couple of RAC instances to check -
and you've got at least 3 handy to do a quick test on.
Regards
Jonathan Lewis
________________________________________
From: Chris Taylor <christopherdtaylor1994@xxxxxxxxx<mailto:
christopherdtaylor1994@xxxxxxxxx><mailto:christopherdtaylor1994@xxxxxxxxx
<mailto:christopherdtaylor1994@xxxxxxxxx>><mailto:
christopherdtaylor1994@xxxxxxxxx<mailto:christopherdtaylor1994@xxxxxxxxx
<mailto:christopherdtaylor1994@xxxxxxxxx<mailto:christopherdtaylor1994@xxxxxxxxx>>>>
Sent: 01 April 2020 16:07
To: Jonathan Lewis
Cc: ORACLE-L
Subject: Re: Weird Situation (12.1.0.2 Exadata Cloud @ Customer) -
Blocking locks with no blocker
Right now I've got 60 sessions waiting on that enqueue lock.
Running this SQL (redacted a bit):
UPDATE <table> SET REVERSED_ON = SYSTIMESTAMP, REVERSING_ID = :B1 WHERE
SOME_ID IN (SELECT * FROM TABLE(:B2 )) ;
@jonathan - I've attached an Excel sheet with locks, sessions and
locking-mode.
We do have some invoicing jobs running when are working on the same
partitions that we're trying to update. But I'm still curious why
blocker/blocking_session is null? If you could help me understand that
part, I'd be most appreciative. I'm beginning to 'feel' like maybe this is
expected type of locking but I want to understand the 'why'.
Also included is a csv of the same if you don't want to crack open the
excel file.
Chris
On Wed, Apr 1, 2020 at 10:30 AM Jonathan Lewis <
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx>><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx>>><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx>><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx><mailto:
jonathan@xxxxxxxxxxxxxxxxxx<mailto:jonathan@xxxxxxxxxxxxxxxxxx>>>>> wrote:
Since you're looking at gv$ does that mean you're running RAC ?
TX - Row lock contention should be reporting mode 6 I think, but could you
check that in case you're waiting for mode 4.
When a session is waiting, are there other sessions also waiting for the
same TX enqueue ?
Regards
Jonathan Lewis
________________________________________
From: oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx
<mailto:oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx>><mailto:oracle-l-bounce@xxxxxxxxxxxxx
<mailto:oracle-l-bounce@xxxxxxxxxxxxx><mailto:
oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx
oracle-l-bounce@xxxxxxxxxxxxx><mailto:oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx<mailto:
<mailto:oracle-l-bounce@xxxxxxxxxxxxx>><mailto:
oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx
<mailto:oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx>>>> <oracle-l-bounce@xxxxxxxxxxxxx<mailto:
oracle-l-bounce@xxxxxxxxxxxxx><mailto:oracle-l-bounce@xxxxxxxxxxxxx
<mailto:oracle-l-bounce@xxxxxxxxxxxxx>><mailto:
oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx
<mailto:oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx>>><mailto:oracle-l-bounce@xxxxxxxxxxxxx
<mailto:oracle-l-bounce@xxxxxxxxxxxxx><mailto:
oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx
oracle-l-bounce@xxxxxxxxxxxxx><mailto:oracle-l-bounce@xxxxxxxxxxxxx<mailto:oracle-l-bounce@xxxxxxxxxxxxx<mailto:
<mailto:oracle-l-bounce@xxxxxxxxxxxxx>>>>> on behalf of Chris Taylor <
christopherdtaylor1994@xxxxxxxxx<mailto:christopherdtaylor1994@xxxxxxxxx
<mailto:christopherdtaylor1994@xxxxxxxxx<mailto:christopherdtaylor1994@xxxxxxxxx>><mailto:christopherdtaylor1994@xxxxxxxxx
<mailto:christopherdtaylor1994@xxxxxxxxx><mailto:
christopherdtaylor1994@xxxxxxxxx<mailto:christopherdtaylor1994@xxxxxxxxx
christopherdtaylor1994@xxxxxxxxx><mailto:christopherdtaylor1994@xxxxxxxxx<mailto:christopherdtaylor1994@xxxxxxxxx<mailto:
<mailto:christopherdtaylor1994@xxxxxxxxx>><mailto:
christopherdtaylor1994@xxxxxxxxx<mailto:christopherdtaylor1994@xxxxxxxxx
<mailto:christopherdtaylor1994@xxxxxxxxx<mailto:christopherdtaylor1994@xxxxxxxxx>>>>>
Sent: 01 April 2020 14:38
To: ORACLE-L
Subject: Weird Situation (12.1.0.2 Exadata Cloud @ Customer) - Blocking
locks with no blocker
We've got a situation where we have sessions experiencing "enq: TX - row
lock contention" with no blocking session.
GV$SESSION.BLOCKING_SESSION is null
DBA_WAITERS is empty
DBA_BLOCKERS is empty
I've gotten around this by joining gv$locked_object to gv$session where
session.wait_class='Idle' and wait_time_micro/1000000 > 120 (seconds).
Some of the locks are for sessions with thousands of wait seconds waiting
on sqlnet.
*BUT* the issue is, why isn't oracle able to find the blocking sessions?
How can I dump/trace the blocking session manually?
In Grid Control we see stuff like: "lock deadlock retry" in the wait
events for the sessions waiting on "enq: TX - row lock".
In the session trace files, we see stuff like "unable to determine final
blocker" .
Any thoughts?
Chris
--
//www.freelists.org/webpage/oracle-l
--
//www.freelists.org/webpage/oracle-l
--
//www.freelists.org/webpage/oracle-l
--
//www.freelists.org/webpage/oracle-l