Re: Reading resource busy error system trace

No. Actually we were not performing any DML on any of the reference tables nor on the same table. That is why we end up setting the trace to see what exact session is blocking and making the ALTER fail. And again if it is the DML on the reference table causing this then the trace should have pointed to the other blocking pid/session rather pointing to the same session which had endup in ora-0054.

And yes you are correct , as per the trace it's saying the same session blocking itself(ALTER statement) post direct path load (loading ~200milion rows) + commit, which is kind of odd. And also surprisingly this same code fails a couple of times and then succeeds on its own after multiple rerun without any other change. And I notice , this failure is happening during the days with high volume load only.

On Sun, Jul 3, 2022 at 2:44 PM Lok P <loknath.73_at_gmail.com> wrote:

> It looks really strange which you have pointed in the trace file though.
> Correct me if wrong, So your blocking session/pid for the 'ALTER' statement
> in the trace is pointing to the same session. And that session has just
> ended up doing direct path load by post disabling constraints/indexes and
> is trying to enable the constraints using ALTER command and is failing with
> Ora-0054. And that to post committing the direct load data. Just a thought,
> are you doing any DML on the parent table which is linked to this
> reference constraint which you are trying to enable here?
>
> On Sat, Jul 2, 2022 at 11:27 PM Pap <oracle.developer35_at_gmail.com> wrote:
>
>> Hello All, I followed the blog below and tried debugging the system
>> trace to find the blocking session/sql which caused this resource busy
>> error, Ora-0054. But I am encountering strange behaviour. It appears to be
>> the same session blocking itself.The session which did the direct path load
>> and commit seems not releasing exclusive lock for some duration post
>> commit. Below are the details of the behaviour. Has anybody
>> encountered such a scenario?
>>
>>
>> https://nenadnoveljic.com/blog/troubleshooting-ora-00054-resource-busy-and-acquire-with-nowait-specified-or-timeout-expired/
>>
>> So the code which is encountering the error is below. Its disabling all
>> constraints + Making index unusable and then does direct path load to that
>> table and then after while trying to enable the constraint of the same
>> table using 'ALTER' and its failing with Ora-0054. The sample code for data
>> load and ALTER table is as below.
>>
>> ****Sample code *****
>> INSERT /*+Append*/ INTO TAB1 (c1,c2.....)
>> SELECT (ROWNUM + sqq_key) ,col1, col2, col3..... from....tab2,
>> tab3, tab4.....;
>> COMMIT;
>>
>> FOR I IN (SELECT TABLE_NAME, CONSTRAINT_NAME FROM ALL_CONSTRAINTS WHERE
>> TABLE_NAME = v_table_nm AND CONSTRAINT_TYPE = 'R' AND STATUS = 'DISABLED')
>> LOOP
>> EXECUTE IMMEDIATE ('ALTER TABLE ' || v_table_nm || ' ENABLE NOVALIDATE
>> CONSTRAINT '|| I.CONSTRAINT_NAME);
>> END LOOP I;
>>
>> ********
>>
>> When i scan through trace file as per the blog step by step, i see below
>>
>> *Step- 1 -* I searched through the object_Id(101739) for TAB1 and got
>> the section below, i.e pointing towards a DML lock on the table. And the
>> process state object is proc: 0x243efffc0.
>>
>> ----------------------------------------
>> SO: 0x233cd8bc8, type: DML lock (83), map: 0x237d28a10
>> state: LIVE (0x4532), flags: 0x0
>> owner: 0x233b9af60, proc: 0x243efffc0
>> link: 0x233cd8be8[0x28acf1e58, 0x1d793c780]
>> pg: 0
>> SOC: 0x237d28a10, type: *DML lock* (83), map: 0x233cd8bc8
>> state: LIVE (0x99fc), flags: INIT (0x1)
>> DML LOCK: tab=101739 flg=11 chi=0
>> his[0]: mod=4 spn=69302
>> 2022-07-01 05:44:10.662*:ksq.c_at_10787:ksqdmc(): Enqueue Dump
>> (enqueue) TM-00018D6B-00000000-00000000-00000000 DID: ksqlkdid:
>> 0001-00CF-000ACD5C
>> lv: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 res_flag: 0x7
>> mode: S, lock_flag: 0x20, lock: 0x237d28a38, res: 0x2499f3798
>> own: 0x2488605f8, sess: 0x2488605f8, *proc: 0x2403a4510*, prv:
>> 0x2499f37a8
>> slk: 0x2530967c8
>> ----------------------------------------
>>
>>
>> *STEP - 2:-* Then i searched through the trace for the state object
>> address i.e. "*SO: 0x243efffc0*" and got below. its pointing to pid:207
>> as below.
>>
>>
>> *** 2022-07-01T05:44:10.538156-04:00
>> PROCESS 207:
>> ----------------------------------------
>> *SO: 0x243efffc0*, type: process (2), map: 0x2403a4510
>> state: LIVE (0x4532), flags: 0x1
>> owner: (nil), proc: 0x243efffc0
>> link: 0x243efffe0[0x243efffe0, 0x243efffe0]
>> child list count: 15, link: 0x243f00030[0x243b7f190, 0x1d7903b10]
>> pg: 0
>> SOC: 0x2403a4510, type: process (2), map: 0x243efffc0
>> state: LIVE (0x99fc), flags: INIT (0x1)
>> (process) *Oracle pid:207,* ser:3445, calls cur/top:
>> 0x1a0372f08/0x1d2ee6c70
>> flags : (0x0) - icon_uid:0 logon_pdbid=0
>> flags2: (0x1000), flags3: (0x510)
>> call error: 0, sess error: 0, txn error 0
>> intr queue: empty
>> (post info) last post received: 0 0 277
>> last post received-location: kcl2.h LINE:5703 ID:kclcget
>> last process to post me: 0x24c3b2180 1 6
>> last post sent: 0 0 33
>> last post sent-location: ksa2.h LINE:298 ID:ksasnd
>> last process posted by me: 0x24837eaa0 1 6
>> waiter on post event: 0
>> (latch info) hold_bits=0x0 ud_influx=0x4101b
>> (osp latch info) hold_bits=0x0 ud_influx=0x0
>> Process Group: DEFAULT, pseudo proc: 0x2484c5d70
>> O/S info: user: grid, term: UNKNOWN, ospid: 383076
>> OSD pid info:
>> Short stack dump:
>>
>> ksedsts()+426<-ksdxfstk()+58<-ksdxdocmdmultex()+5961<-ksdxdocmdmult()+55<-ksudmp_proc()+1626<-ksudss_main()+1976<-ksudss_opt()+1544<-dbkdaKsdActDriver()+2484<-dbgdaExecuteAction()+354<-dbgdaRunAction()+770<-dbgdRunActions()+83<-dbgdProcessEventActions()+525<-dbgdChkEventKgErr()+394<-dbkdChkEventRdbmsErr()+65<-dbgePostErrorKGE()+1066<-dbkePostKGE_kgsf()+71<-kgeade()+338<-kgeselv()+89<-ksesecl0()+189<-ktaiam()+1110<-ktagetg0()+929<-ktagetp_internal()+141<-ktagetg_ddlX()+323<-ktagetg_ddl()+30<-kkdllk0()+1551<-kkdcprc()+711<-kkdcmco()+3682<-atbadd()+8770<-atbdrv()+14663<-opiexe()+30061<-opiosq0()+4575<-opipls()+14619<-opiodr()+1202<-rpidrus()+198<-skgmstack()+65<-rpidru()+132<-rpiswu2()+614<-rpidrv()+1494<-psddr0()+467<-psdnal()+646<-pevm_EXIM()+276<-pfrinstr_EXIM()+43<-pfrrun_no_tool()+52<-pfrrun()+902<-plsql_run()+755<-peicnt()+279<-kkxexe()+720<-opiexe()+24762<-kpoal8()+2226<-opiodr()+1202<-ttcpip()+1239<-opitsk()+1897<-opiino()+936<-opiodr()+1202<-opidrv()+1094<-sou2o()+165<-opimai_real()+422<-ssthrdmain()+417<-main()+256<-__libc_start_main()+245
>>
>> KGL-UOL (Process state object)
>> KGX Atomic Operation Log 0x2403a5690
>> Mutex (nil)(0, 0) idn 0 oper NONE(0)
>> FSO mutex uid 262142 efd 0 whr 0 slp 0
>> KGX Atomic Operation Log 0x2403a56f8
>> Mutex (nil)(0, 0) idn 0 oper NONE(0)
>> FSO mutex uid 262142 efd 0 whr 0 slp 0
>> KGX Atomic Operation Log 0x2403a5760
>> Mutex (nil)(0, 0) idn 0 oper NONE(0)
>> FSO mutex uid 262142 efd 0 whr 0 slp 0
>> KGX Atomic Operation Log 0x2403a57c8
>> Mutex (nil)(0, 0) idn 0 oper NONE(0)
>> FSO mutex uid 262142 efd 0 whr 0 slp 0
>> KGX Atomic Operation Log 0x2403a5830
>> Mutex (nil)(0, 0) idn 0 oper NONE(0)
>> FSO mutex uid 262142 efd 0 whr 0 slp 0
>> KGX Atomic Operation Log 0x2403a5898
>> Mutex (nil)(0, 0) idn 0 oper NONE(0)
>> FSO mutex uid 262142 efd 0 whr 0 slp 0
>> KGX Atomic Operation Log 0x2403a5900
>> Mutex (nil)(0, 0) idn 0 oper NONE(0)
>> FSO mutex uid 262142 efd 0 whr 0 slp 0
>> KGX Atomic Operation Log 0x2403a5968
>> Mutex (nil)(0, 0) idn 0 oper NONE(0)
>> FSO mutex uid 262142 efd 0 whr 0 slp 0
>> KGX Atomic Operation Log 0x2403a59d0
>> Mutex (nil)(0, 0) idn 0 oper NONE(0)
>> FSO mutex uid 262142 efd 0 whr 0 slp 0
>> ----------------------------------------
>>
>>
>> *Step-3 :- * Then searching for the *pid-207* in the start of the trace
>> , i found *sid - 1072 ser 23 *and its pointing to the same ALTER TABLE
>> statement. The OSPID is the same one for which the trace gets generated.
>> And if I try to see the DML in this sesion before this ALTER it's the same
>> one, which has just finished up doing the COMMIT for the direct path load.
>>
>> So I am wondering , is it possible that we are hitting any bug due to
>> which Oracle is actually not releasing the Exclusive table lock immediately
>> post Commit of the direct path load ? And that is why , even if we are
>> trying to do the ALTER post COMMIT in the same session we are hitting
>> Ora-0054 as it blocks itself? And then should we put some wait/sleep
>> statement post commit i.e. before the ALTER to avoid this bug?
>>
>> 207: USER ospid 383076 sid 1072 ser 23,
>> Cmd: ALTER TABLE
>>
>> On Mon, Jun 13, 2022 at 4:28 PM Pap <oracle.developer35_at_gmail.com> wrote:
>>
>>> Thank You So much Nenad.
>>>
>>> Unfortunately while checking with the team got to know that the other
>>> trace files has been removed from the location. So i will wait for the next
>>> occurrence of the error to capture and analyze all the traces wrt that one
>>> ospid.
>>>
>>>
>>> On Sun, 12 Jun 2022, 9:24 pm Noveljic Nenad, <
>>> nenad.noveljic_at_vontobel.com> wrote:
>>>
>>>> Your system dump apparently consists of several files.
>>>>
>>>>
>>>>
>>>> At the very beginning of the system dump there must be a section that
>>>> identifies the blockers for each process and looks something like this:
>>>>
>>>> 157: USER ospid 1385877 sid 786 ser 49681, waiting for 'log file switch
>>>> (checkpoint incomplete)'
>>>>
>>>> Cmd: INSERT
>>>>
>>>> Blocked by inst: 1, sid: 266, ser: 13238
>>>>
>>>> Final Blocker inst: 1, sid: 266, ser: 13238
>>>>
>>>> 159: USER ospid 1295896 sid 796 ser 48963, waiting for 'log file switch
>>>> (checkpoint incomplete)'
>>>>
>>>> Cmd: INSERT
>>>>
>>>> Blocked by inst: 1, sid: 266, ser: 13238
>>>>
>>>> Final Blocker inst: 1, sid: 266, ser: 13238
>>>>
>>>>
>>>>
>>>> First, check who was blocking the Powercenter process with ospid 89092
>>>> (Blocked by…). Then search **all** system dump trace files (**89092**.trc)
>>>> for the blocker to look at its state objects. Once you now the sid and
>>>> serial of the blocker, you can position yourself to its state objects with
>>>> the following search expression: sid: xxx ser: xxx . One of the state
>>>> objects will be for the cursor that blocked your DDL on MAIN_TAB.
>>>>
>>>>
>>>>
>>>> Best regards,
>>>>
>>>>
>>>>
>>>> Nenad
>>>>
>>>>
>>>>
>>>> *From:* Pap <oracle.developer35_at_gmail.com>
>>>> *Sent:* Sonntag, 12. Juni 2022 14:06
>>>> *To:* Noveljic Nenad <nenad.noveljic_at_vontobel.com>
>>>> *Cc:* Oracle L <oracle-l_at_freelists.org>
>>>> *Subject:* Re: Reading resource busy error system trace
>>>>
>>>>
>>>>
>>>> Thank You Nenad.
>>>>
>>>> So actually here the session/Alter statement, which failed, is from the
>>>> informatica power center session only. So do you mean we should search the
>>>> body of the original trace file from which this trace continued from i.e "u01/app/oracle/diag/rdbms/DB1p/DB11/trace/DB11_ora_89092_8.trc"
>>>> rather this one. And in that trace the sql statements near the "final
>>>> blocker" string will be the cause of this error?
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
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