Oracle等待事件KJC:Wait for msg sends to complete

KJC: Wait for msg sends to complete是一种只会发生在RAC环境中的等待事件,目前对于该等待事件已知的信息不多。
KJ意为Kernel Lock Management Layer,Messaging Enhancements (KJC)。
猜测该等待事件为global enqueue message的网络传输等待,前台进程和后台进程如LMS、LMD均可能发生该等待事件。

 

select name,parameter1,parameter2,parameter3,wait_class from v$event_name where name like '%KJC%';

NAME                                                             PARAMETER1
---------------------------------------------------------------- ----------------------------------------------------------------
PARAMETER2                                                       PARAMETER3
---------------------------------------------------------------- ----------------------------------------------------------------
WAIT_CLASS
----------------------------------------------------------------
KJC: Wait for msg sends to complete                              msg
dest|rcvr                                                        mtype
Other

SQL> select * from gV$system_Event where event like '%KJC%';

   INST_ID EVENT                                                            TOTAL_WAITS
---------- ---------------------------------------------------------------- -----------
TOTAL_TIMEOUTS TIME_WAITED AVERAGE_WAIT TIME_WAITED_MICRO TOTAL_WAITS_FG TOTAL_TIMEOUTS_FG
-------------- ----------- ------------ ----------------- -------------- -----------------
TIME_WAITED_FG AVERAGE_WAIT_FG TIME_WAITED_MICRO_FG   EVENT_ID WAIT_CLASS_ID WAIT_CLASS#
-------------- --------------- -------------------- ---------- ------------- -----------
WAIT_CLASS
----------------------------------------------------------------
         2 KJC: Wait for msg sends to complete                                      415
             0           1            0              7638            163                 0
             0               0                 2494 4079369678    1893977003           0
Other

         1 KJC: Wait for msg sends to complete                                       93
             0           0            0              2094             37                 0
             0               0                  615 4079369678    1893977003           0
Other

注意到该等待事件的类别是other而非concurrency,若发生该等待事件我们应当关心的是网络性能
netstat -s or ifconfig?

以下为具体的等待发生场景:

PARSING IN CURSOR #140438030304224 len=169 dep=2 uid=0 oct=3 lid=0
tim=1310310630713104 hv=2411583655 ad='b5a49898' sqlid='637txtu7vvq57'
select service_name, service_name_hash,wait_class_id, wait_class#,  wait_class,total_waits, time_waited  from
gv$service_wait_class where inst_id = USERENV('Instance')

END OF STMT
PARSE #140438030304224:c=6999,e=7685,p=0,cr=5,cu=0,mis=1,r=0,dep=2,og=4,plh=809657567,tim=1310310630713101
CLOSE #140438030304224:c=0,e=20,dep=2,type=0,tim=1310310630713388
WAIT #140438029567384: nam='row cache lock' ela= 530 cache id=8 mode=0 request=3 obj#=6623 tim=1310310630716555
EXEC #140438032451672:c=0,e=61,p=0,cr=0,cu=0,mis=0,r=0,dep=2,og=4,plh=2853959010,tim=1310310630716708
FETCH #140438032451672:c=0,e=49,p=0,cr=4,cu=0,mis=0,r=1,dep=2,og=4,plh=2853959010,tim=1310310630716809
CLOSE #140438032451672:c=0,e=10,dep=2,type=3,tim=1310310630716877

WAIT #140438029567384: nam='KJC: Wait for msg sends to complete' ela= 18
msg=3235372280 dest|rcvr=65536 mtype=12 obj#=6623 tim=1310310630719146

EXEC #140438032420328:c=0,e=190,p=0,cr=1,cu=5,mis=0,r=1,dep=1,og=4,plh=0,tim=1310310630781989

WAIT #140438032420328: nam='KJC: Wait for msg sends to complete' ela= 55
msg=3235374760 dest|rcvr=65537 mtype=32 obj#=74418 tim=1310310630782830

这里的msg猜测可能是递增的message id
mytpe为该msg的类型
obj#为对象号

KJC: Wait for msg sends to complete可能的相关stack call:

LMS's stack:
ksedms ksdxfdmp ksdxcb sspuser sigacthandler libc_poll
kslwait ksxprcv kjctr_rksxp kjctsrw kjccwcrm kjccqmg
kjbmsclose kjbclose kclpdc kclpdcl kclpbi kjmsm
ksbrdp opirip opidrv sou2o main start 

 LMS4 was waiting for  "KJC: Wait for msg sends to complete"

  'KJC: Wait for msg sends to complete', at one of the stack trace
  below

  o kjccqmg => kjctcwcrm
  o kjccsmg => kjctcwcrm

o  an Oracle process is spinning in kjctcwcrm() on 9.0, 9.2 or 10.1

o  an Oracle process got ORA-600[kjccgmb:1] on 9.0, 9.2 or 10.1

o Got ORA-7445[] at an unknown function called from kjbmmsg2res()
o A LMS process hung in kjctcwcrm() on shutdown

LMS may hang waiting for 'kjc: wait for msg sends to complete'
during shutdown of an instance with another session
reporting ORA-600 [kjccgmb:1]

IAGNOSTIC ANALYSIS:
--------------------
Let the customer tracing the lmon, lmd when doing the shutdown immediate,
find out:
    In sur11_lmon_5948.trc
    WAIT #0: nam='ges LMD to shutdown' ela= 496057 p1=0 p2=0 p3=0
    WAIT #0: nam='KJC: Wait for msg sends to complete' ela= 49213 p1=0 p2=0
p3=0
    WAIT #0: nam='KJC: Wait for msg sends to complete' ela= 49811 p1=0 p2=0
p3=0
    WAIT #0: nam='KJC: Wait for msg sends to complete' ela= 49772 p1=0 p2=0
p3=0
    WAIT #0: nam='KJC: Wait for msg sends to complete' ela= 49813 p1=0 p2=0
p3=0
    WAIT #0: nam='KJC: Wait for msg sends to complete' ela= 49779 p1=0 p2=0
p3=0
    WAIT #0: nam='KJC: Wait for msg sends to complete' ela= 49787 p1=0 p2=0
p3=0
    WAIT #0: nam='KJC: Wait for msg sends to complete' ela= 49779 p1=0 p2=0 

	LMS4's stack:
ksedms ksdxfdmp ksdxcb sspuser sigacthandler libc_poll
kslwait ksxprcv kjctr_rksxp kjctsrw kjccwcrm kjccqmg
kjbmsclose kjbclose kclpdc kclpdcl kclpbi kjmsm
ksbrdp opirip opidrv sou2o main start 

LMS4 was encountered ORA-4031 during shutting down,

#0  0x0000000004f5bdbe in kjccqmg ()
#1  0x0000000005172378 in kjbmflushsc ()
#2  0x0000000005175351 in kjbmfto ()
#3  0x0000000004ff425f in kjmsm ()
#4  0x00000000022677a7 in ksbrdp ()
#5  0x000000000248c8a3 in opirip ()
#6  0x000000000171eefd in opidrv ()
#7  0x0000000001d95f5f in sou2o ()
#8  0x0000000000a079ba in opimai_real ()
#9  0x0000000001d9b408 in ssthrdmain ()
#10 0x0000000000a078a1 in main ()

(gdb) bt
#0  0x00000000053907aa in kclpbi ()
#1  0x0000000004ff46dc in kjmsm ()
#2  0x00000000022677a7 in ksbrdp ()
#3  0x000000000248c8a3 in opirip ()
#4  0x000000000171eefd in opidrv ()
#5  0x0000000001d95f5f in sou2o ()
#6  0x0000000000a079ba in opimai_real ()
#7  0x0000000001d9b408 in ssthrdmain ()
#8  0x0000000000a078a1 in main ()

(gdb) bt
#0  0x0000000004f5bdbe in kjccqmg ()
#1  0x00000000051a232a in kjbmswrite ()
#2  0x00000000051014f1 in kjbrswrite ()
#3  0x00000000050fec8d in kjbrwreq ()
#4  0x0000000005189fcc in kjbmpwrite ()
#5  0x0000000004fe98fe in kjmxmpm ()
#6  0x0000000004feceee in kjmpmsgi ()
#7  0x0000000004ff2d8e in kjmsm ()
#8  0x00000000022677a7 in ksbrdp ()
#9  0x000000000248c8a3 in opirip ()
#10 0x000000000171eefd in opidrv ()
#11 0x0000000001d95f5f in sou2o ()
#12 0x0000000000a079ba in opimai_real ()
#13 0x0000000001d9b408 in ssthrdmain ()
#14 0x0000000000a078a1 in main ()

以下列出了与该’KJC: Wait for msg sends to complete’相关的Bug信息

Bug Affected Version Description
Bug 5075434 Small performance overhead in RAC (waits for “KJC: Wait for msg sends to complete”) 10.2.0.2 RAC session can suffer a small performance overhead due to waiting for a timeout on “KJC: Wait for msg sends to complete”.
Bug 11687519: PZ99 PROCESS SPIN WITH “KJC: WAIT FOR MSG SENDS TO COMPLETE” 10.2.0.3 Abstract: PZ99 PROCESS SPIN WITH “KJC: WAIT FOR MSG SENDS TO COMPLETE”
Bug 4672266: LMS WAITING FOR ‘KJC: WAIT FOR MSG SENDS TO COMPLETE’ WHILE SHUTDOWN 9.2.0.4 Abstract: LMS WAITING FOR ‘KJC: WAIT FOR MSG SENDS TO COMPLETE’ WHILE SHUTDOWN LMS2 has been waiting for the event ‘KJC: Wait for msg sends to complete’
while SHUTDOWN IMMEDIATE.
My customer decided to issue SHUTDOWN ABORT to stop the instance in one hour.
Bug 4672266 LMS hang waiting for ‘kjc: wait for msg sends to complete’ during shutdown 9.2.0.4 9.2.0.7 10.1.0.5 10.2.0.2 LMS may hang waiting for ‘kjc: wait for msg sends to complete’ during shutdown of an instance with another session reporting ORA-600 [kjccgmb:1]
Bug 2447621 – Unneccessary waits for “KJC: WAIT FOR MSG SEND COMPLETION” <9.2 Unneccessary waits for “KJC: Wait for message completion” can occur in a RAC environment.
Bug 5347566: SHUTDOWN IMMEDIATE VERY SLOW WITH ‘KJC: WAIT FOR MSG SENDS TO COMPLETE’ 9.2.0.7 Exactly similar as Bug 5289823 and Bug 4672266 LMS hang waiting for ‘kjc: wait for msg sends to complete’ during shutdown
Bug 5084699: RACGIMON WAITING FOR ‘KJC: WAIT FOR MSG SENDS TO COMPLETE’ 10.2.0.1 racgimon on one of the 4 nodes cluster has been exhibiting process spin.
It appears to wait for 15 minutes every 20 minutes on “KJC: Wait for msg
sends to complete” in the following PL/SQL execution:
‘begin dbms_lock.allocate_unique(:a1, :a2); end;’
Bug 3561040: SHUTDOWN HANG DUE TO LMS PROCESS WAITING FOR KJC: WAIT FOR MSG SENDS TO COMPLETE 9.2.0.4 LMS process is waiting for  “KJC: Wait for msg sends to complete” while shutdown and shutdown does not complete.

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Comments

  1. liumaclean says:

    May be The root cause is Bug 5075434, RAC session can suffer a small performance overhead due to waiting for a timeout on “KJC: Wait for msg sends to complete”.
    So can you please perform the following solution to fix this issue:

    1. apply 10.2.0.3 (Server Patch Set) or higher patch set.
    or
    2. apply one off patch 5075434 on the top of 10.2.0.2.

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