High CPU usage on MaxDb instance

Former Member · ‎05-21-2014

Hello Everyone,

I have a system showing high load on the CPU :

top - 00:05:05 up 311 days, 13:03, 9 users, load average: 50.72, 127.39, 110.54

Tasks: 500 total, 1 running, 499 sleeping, 0 stopped, 0 zombie

Cpu(s): 0.3%us, 0.3%sy, 0.0%ni, 64.8%id, 34.3%wa, 0.0%hi, 0.0%si, 0.3%st

Mem: 49160M total, 48507M used, 652M free, 149M buffers

Swap: 20479M total, 1940M used, 18539M free, 3548M cached

I checked everything and noticed shared memory error in the dbmsrv file

Can anyone let me know if the shared memory could be a cause in the high load?

Or do I need to do any other basic checks?

Any help would be appreciated

Below is the output of 'x_cons HPT show active :

ID UKT UNIX TASK APPL Current Timeout/ Region Wait

tid type pid state Priority cnt try item

T2 2 18679 Logwr Vector IO 9 124866639(r)

T68 12 18689 User 23028* LogIOwait(234) 1 0 68 784358517(r)

T71 13 18690 User 23710* Vwait 0 909589452(s)

T78 17 18694 User 3024* LogIOwait(234) 0 906420743(r)

T79 9 18686 User 27748* LogIOwait(234) 0 750068811(r)

T90 11 18688 User 28215* Vwait 0 845220668(r)

T95 8 18685 User 32328* LogIOwait(234) ! 0 804631101(r)

T114 16 18693 User 20711**Command wait no 0 888322907(r)

T117 13 18690 User 18944* LogIOwait(234) 0 909589452(s)

T120 13 18690 User 28175* Vwait 0 909589452(s)

T141 18 18695 User 5611* Vwait 0 890340046(s)

T149 9 18686 User 29715* Connect close 5 750068811(r)

T320 16 18693 User 20068* Vwait 0 888322907(r)

T369 9 18686 User 28212* LogIOwait(234) 0 750068811(r)

T370 10 18687 User 3699* LogIOwait(234) ! 0 745931359(s)

T378 11 18688 User 28206* Vwait 0 845220668(r)

T454 18 18695 User 27238* IO Wait (R) ! 0 51 890340046(s)

T456 10 18687 User 3129* LogIOwait(234) 0 745931359(s)

T457 9 18686 User 29232* LogIOwait(234) 0 750068811(r)

T461 18 18695 User 28223* IOWait(R)(041) 0 890340046(s)

T463 12 18689 User 28177* Vector IO 0 784358517(r)

T470 10 18687 User 11683* LogIOwait(234) 0 745931359(s)

T473 8 18685 User 16966* Vwait 0 804631101(r)

T482 13 18690 User 13975* LogIOwait(234) 0 909589452(s)

T489 16 18693 User 28232**Command wait no 0 51 888322907(r)

T497 11 18688 User 18937* Connect close 17 845220668(r)

T500 11 18688 User 28207* Enter ShareLck 0 SQL_SessionList 1 (w) 845220668(r)

T503 10 18687 User 30325* LogIOwait(234) 0 745931397(s)

T505 16 18693 User 28221**Command wait no 0 888322907(r)

T577 15 18692 User 1940* Connect close ! 17 898282814(r)

T582 11 18688 User 13480* LogIOwait(234) 0 845220668(r)

T585 18 18695 User 1560* LogIOwait(234) ! 0 890340051(s)

T590 18 18695 User 20116* LogIOwait(234) 0 890340051(s)

T594 9 18686 User 5409* LogIOwait(234) ! 0 750068816(s)

T624 9 18686 User 1225* Vwait 0 750068816(s)

T639 16 18693 User 28253* LogIOwait(234) 0 888322907(r)

T658 13 18690 User 3719* LogIOwait(234) 0 909589453(s)

T663 9 18686 User 28247* Vwait 0 750068816(s)

T687 16 18693 User 27614* LogIOwait(234) ! 0 888322907(r)

T715 12 18689 User 4077* Vwait 0 784358517(r)

T724 8 18685 User 23921* LogIOwait(234) 0 804631101(r)

T727 13 18690 User 31523* LogIOwait(234) 0 909589453(s)

T731 12 18689 User 28205* Vwait 0 784358517(r)

T745 18 18695 User 27608* LogIOwait(234) ! 0 890340051(s)

T748 9 18686 User 17691* Vwait 0 750068816(s)

T754 16 18693 User 11312**Command wait no 0 888322907(r)

T759 16 18693 User 1514**LogIOwait(234) 5 0 888322907(r)

T761 15 18692 User 27641* LogIOwait(234) ! 0 898282814(r)

T766 11 18688 User 3745* LogIOwait(234) 0 845220668(r)

T771 9 18686 User 23176* Vwait 0 750068816(s)

T777 9 18686 User 30883* Vwait 0 750068816(s)

T781 18 18695 User 22235* LogIOwait(234) ! 0 890340051(s)

T787 17 18694 User 5980* Connect close 5 906420743(r)

T790 8 18685 User 5420* LogIOwait(234) 0 804631101(r)

T813 17 18694 User 2476* LogIOwait(234) ! 0 906420743(r)

T823 14 18691 User 309**Enter ShareLck 7 0 SQL_SessionList 1 (w) 902276702(r)

T832 8 18685 User 20739* LogIOwait(234) 0 804631101(r)

T845 13 18690 User 24777* LogIOwait(234) 0 909589453(s)

T850 13 18690 User 30893* LogIOwait(234) 0 909589453(s)

T853 14 18691 User 28194* Vwait 0 902276702(r)

T858 8 18685 User 23512* LogIOwait(234) 0 804631101(r)

T861 14 18691 User 20739* Vwait 0 902276702(r)

T865 18 18695 User 23706* Vwait 0 890340052(s)

T868 12 18689 User 20733* LogIOwait(234) 0 784358517(r)

T874 11 18688 User 28239* LogIOwait(234) 0 845220668(r)

T888 18 18695 User 22080* IOWait(R)(041) 0 890340052(s)

T894 13 18690 User 12231* Enter ShareLck 0 SQL_SessionList 1 (w) 909589453(s)

T895 17 18694 User 2578* Vwait ! 0 906420767(s)

T944 16 18693 User 23704* LogIOwait(234) 0 888322916(r)

T951 10 18687 User 5932* Vwait 0 745931493(s)

T953 10 18687 User 28252* Vwait 0 745931493(s)

T961 14 18691 User 28154* Running 296 902276747(r)

T972 10 18687 User 23711* Vwait 0 745931493(s)

T975 16 18693 User 22238* LogIOwait(234) 0 888322916(r)

T980 11 18688 User 2907* Vwait 0 845220677(s)

T989 14 18691 User 23714* LogIOwait(234) 0 902276747(r)

T1009 13 18690 User 9270* LogIOwait(234) 0 909589459(s)

T1010 15 18692 User 6137* LogIOwait(234) 0 898282825(s)

T1023 10 18687 User 28180* LogIOwait(234) 0 745931493(s)

T1041 15 18692 User 16138* Vwait 0 898282825(s)

T1047 9 18686 User 28161* Vwait 0 750068824(s)

T1067 18 18695 User 28168* IOWait(R)(041) 0 890340099(s)

T1068 15 18692 User 12678* Vwait 0 898282825(s)

T1070 10 18687 User 18967* LogIOwait(234) ! 0 745931493(s)

T1084 9 18686 User 16135* LogIOwait(234) 0 750068824(s)

T1100 10 18687 User 11196* LogIOwait(234) 0 745931493(s)

T1114 13 18690 User 1972* Vwait 0 909589459(s)

T1134 15 18692 User 28225* Vwait 0 898282825(s)

T1138 13 18690 User 23709* Vwait 0 909589459(s)

T1163 13 18690 User 28200* IO Wait (R) 0 16 909589459(s)

T1166 8 18685 User 28188* LogIOwait(234) 0 804631119(s)

T1199 18 18695 User 22297* Vwait 0 890340099(s)

T1211 17 18694 User 31118* Vwait 0 906420767(s)

T1240 17 18694 User 12901* LogIOwait(234) 0 906420767(s)

T1265 9 18686 User 14086* LogIOwait(234) 0 750068824(s)

T1286 15 18692 User 28230* Vwait 0 898282825(s)

T1313 15 18692 User 28220* Vwait 0 898282825(s)

T1314 16 18693 User 14699* LogIOwait(234) 0 888322916(r)

T1316 15 18692 User 28155* LogIOwait(234) 0 898282825(s)

T1342 12 18689 User 28222* Vwait 0 784358541(s)

T1344 17 18694 User 1557* LogIOwait(234) ! 0 906420767(s)

T1365 18 18695 User 28234* Vwait 0 890340099(s)

T1370 17 18694 User 28236* Vwait 0 906420767(s)

T1376 12 18689 User 28158* Vwait 0 784358541(s)

T1378 11 18688 User 10397* Vwait 0 845220677(s)

T1384 8 18685 User 28245* Vwait 0 804631119(s)

T1420 14 18691 User 24592* Vwait 0 902276747(r)

T1440 11 18688 User 22960* LogIOwait(234) 0 845220677(s)

T1463 9 18686 User 28185* Vwait 0 750068824(s)

T1471 11 18688 User 27611* Vwait 0 845220677(s)

T1496 8 18685 User 31179* LogIOwait(234) 0 804631119(s)

T1501 12 18689 User 28973* LogIOwait(234) 0 784358541(s)

T1517 14 18691 User 23708* Vwait 0 902276747(r)

T1524 16 18693 User 28151* Vwait 0 888322916(r)

T1547 10 18687 User 28216* IO Wait (R) 0 5 745931493(s)

T1558 15 18692 User 15863* LogIOwait(234) 0 898282825(s)

T1593 12 18689 User 22513* Vwait 0 784358541(s)

T1597 12 18689 User 12902* Vwait 0 784358541(s)

T1601 9 18686 User 23173* LogIOwait(234) ! 0 750068824(s)

T1604 8 18685 User 31556* Vwait 0 804631119(s)

T1612 10 18687 User 1281* LogIOwait(234) ! 0 745931493(s)

T1646 14 18691 User 4260* Vwait 0 902276747(r)

T1649 10 18687 User 23862* Vwait 0 745931493(s)

T1664 8 18685 User 32197* Vwait 0 804631119(s)

T1666 16 18693 User 23735* LogIOwait(234) 0 888322916(r)

T1676 12 18689 User 15167* Vwait 0 784358541(s)

T1680 18 18695 User 22282* Vwait 0 890340099(s)

T1683 9 18686 User 3034* LogIOwait(234) 0 750068824(s)

T1686 9 18686 User 23364* Vwait 0 750068824(s)

T1696 17 18694 User 28244* Vector IO 0 906420767(s)

T1709 14 18691 User 15351* Vwait 0 902276747(r)

T1733 18 18695 User 30535* IOWait(R)(041) 0 890340099(s)

T1735 11 18688 User 28179* LogIOwait(234) 0 845220677(s)

T1738 18 18695 User 22187* LogIOwait(234) 0 890340099(s)

T1740 14 18691 User 28160* Vwait 0 902276747(r)

T1779 16 18693 User 22606* Vwait 0 888322916(r)

T1843 12 18689 User 28224* Vwait 0 784358541(s)

T1849 15 18692 User 23707* LogIOwait(234) 0 898282825(s)

T1859 10 18687 User 28197* IOWait(R)(041) 0 745931493(s)

T1874 16 18693 User 28951* Vwait 0 888322916(r)

T1887 9 18686 User 29220* LogIOwait(234) ! 0 750068824(s)

T1913 15 18692 User 5598* Vwait 0 898282825(s)

T1918 9 18686 User 9654* Vwait 0 750068824(s)

T1924 17 18694 User 24524* Vwait 0 906420767(s)

T1950 8 18685 User 16727* LogIOwait(234) 0 804631119(s)

T1953 12 18689 User 10400* Vwait 0 784358541(s)

T1964 8 18685 User 23729* LogIOwait(234) 0 804631119(s)

T1967 18 18695 User 31693* Vwait 0 890340099(s)

T1992 16 18693 User 28184* Vwait 0 888322916(r)

T1998 16 18693 User 5737* Vwait 0 888322916(r)

T2003 14 18691 User 28204* Vwait 0 902276747(r)

T2008 9 18686 User 28240* LogIOwait(234) 0 750068824(s)

T2012 10 18687 User 28241* Vwait 0 745931493(s)

T2014 14 18691 User 20680* Vwait 0 902276747(r)

T2018 4 18681 PrefLOB Vector IO 0 325778572(s)

T2019 4 18681 PrefLOB Vector IO 0 325778572(s)

T2221 4 18681 Savepnt IO Wait (W) 0 14 325778572(s)

T2222 4 18681 AutoLgW Vsuspend (204) 0 325778572(s)

T2223 4 18681 AutoLgR Vector IO 0 325778572(s)

Regards,

Vinay

Former Member · ‎05-22-2014

Hi Vinay,

the x_cons output does not show any user tasks with CPU usage. There are all in some kind of wait situation. It really looks strange.

We have a lot of User Tasks in status VWAIT ->
T2014 14 18691 User 20680* Vwait 0 902276747(r)

-> vwait means that the Task requested a SQL lock but could not get this lock because it ia already locked by another task. The task has to wait -> Please check the SDQL LockSituation.

Then I see a lot of Tasks in LOGIOWAIT
T1166 8 18685 User 28188* LogIOwait(234) 0 804631119(s)

There are as well in a wait situation - write Log to disk - the reason for the suspent is no: 234

If you run x_cvons show supend you will get a list of Wiat situations ->

Which string do you get for 234

We see as well that you already tried to cancel or kill some of the Tasks -> see the '!'
T895 17 18694 User 2578* Vwait ! 0 906420767(s)

We have also read wait situation on the log - looks like a rollback is curerntly active as well.

If this is a SAP system I would recommend to open a SAP ticket to check the system directly.

Regards, Christiane

former_member188883 · ‎05-21-2014

Hi Vinay,

As we are not sure about which MaxDB version you have , my suggestion is to have a look into below SAP note

Note 1318372 - Performance problem with MaxDB 7.7: High CPU system load

Some performance issues are addressed here.

Hope this helps.

Regards,

Deepak Kori

High CPU usage on MaxDb instance

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