RAC LMS Process Using High CPU (Doc ID 1996389.1)

Last updated on APRIL 09, 2015

Applies to:

Oracle Database - Enterprise Edition - Version 11.2.0.4 to 12.1.0.1 [Release 11.2 to 12.1]
Information in this document applies to any platform.

Symptoms

11.2.0.4 RAC cluster, random LMS process spins CPU and stays high:

 

In this example, for the following period, LMS1 is using 100% of CPU most of the time: 

zzz ***Tue Mar 17 16:35:03 PDT 2015
79535 oracle -2 0 900g 465m 21m R 100.0 0.0 5:08.01 oracle
...
zzz ***Tue Mar 17 18:31:40 PDT 2015
79535 oracle -2 0 900g 472m 21m R 99.4 0.0 120:01.20 oracle

 

And it used far more CPU than any other LMS for the same instance: 

zzz ***Tue Mar 17 18:31:40 PDT 2015
oracle 79535 1 41 85.6 0.0 718180 484024 - R 16:11:35 01:59:59 ora_lms1_ip4data <<<
oracle 79543 1 41 9.2 0.0 717412 483228 poll_s S 16:11:35 00:12:58 ora_lms3_ip4data
oracle 79539 1 41 8.7 0.0 717412 483472 poll_s S 16:11:35 00:12:17 ora_lms2_ip4data
oracle 79531 1 41 8.5 0.0 717668 483252 poll_s S 16:11:35 00:11:57 ora_lms0_ip4data


Call stack of LMS is the following all the time: 

#0 0x00000000094af32a in kcbgtcr ()
#1 0x000000000951b988 in ktrget3 ()
#2 0x000000000951b02e in ktrget2 ()
#3 0x000000000575a3e9 in kclgeneratecr ()
#4 0x00000000057672ad in kclgcr ()
#5 0x000000000576eb4c in kclcrrf ()
#6 0x00000000054b5774 in kjblcrcbk ()
#7 0x00000000054b616c in kjblpcr ()
#8 0x00000000054e22b0 in kjbmpbast ()
#9 0x00000000053325a0 in kjmxmpm ()
#10 0x00000000053355c8 in kjmpbmsg ()
#11 0x000000000533beb4 in kjmsm ()
<< repeated

 

The following repeated thousands of times in LMS trace for the same block after turned on event 10708 at level 3: 

2015-03-27 17:05:09.365911 : kjblcrcbk(0x8fcf9.ea)(flockp 0x106fd80578)(rinst 2)(rreqid x7203)(flgs x4000)(gr 0)(rscn x7d7.9eaa46f2)
kclcrrf: req=2372567 block=234/589049
KCL: F237: cannot serve: weak clone
kclgcr: req=2372567 status=fail

 



Cause

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