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IT26370: IN A DB2 PURESCALE CLUSTER CONTAINING 8 OR MORE MEMBERS, APPLICATIONS MAY INDEFINITELY HANG IN LOCK-WAIT STATUS.

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APAR status

  • Closed as program error.

Error description

  • In a Db2 pureScale cluster containing 8 or more members, if
    member 7 is holding the Global Deadlock Detector(GDD) lock, then
    the other members in the cluster may not be able to detect and
    resolve deadlocks. This can lead to applications indefinitely
    hanging in Lock-wait status. In order to determine which Db2
    member is holding the GDD lock for a particular database, the
    following db2pd command can be run:
    
    db2pd -fmtlock -db <DBNAME>
    
    In the output of this command, the following information
    regarding the GDD lock (SQLP_GLOBAL_PHYSICAL_LOCK_GDD) will be
    displayed:
    
    HDR=0x7f9b20c0b2a0  HashIndex=18724 HashPointer=0x7f9b1ea76140
    LockName=010000000000000000000000E7
    SQLP_GLOBAL_NONRETAINED_PHYSICAL
         LockDetails:SQLP_GLOBAL_PHYSICAL_LOCK_GDD
         GroupMode=NON Flags=0000 Flags2=00 numConv=0
    numAgentsWithoutLrb=0
         lastGranted=(nil) PLockDataPtr=(nil)
         notAwareAttributes=00 numSLSInFlight=0 holdingLLM=8
         cmrrIID=0 aggregatedrrIID=0
    
    If the value of holdingLLM set to 8 as shown above, then it
    means that member 7 is currently holding the GDD lock.
    Furthermore, if member 7 is holding the GDD lock, then the
    following db2diag.log error message will be seen every 10
    seconds on all other members in the cluster:
    
    2018-08-29-19.01.39.211711-180 I74899547A351       LEVEL: Error
    PID    : 8781890             TID : 121588        PROC : db2sysc
    0
    INSTANCE: db2inst1            NODE : 000          DB  : PUREDB
    HOSTNAME: purehost01
    EDUID  : 121588              EDUNAME: db2dlock (PUREDB) 0
    FUNCTION: DB2 UDB, lock manager, sqlplLDDManageGDDComm,
    probe:100
    

Local fix

  • Recycle Db2 member 7 so that it gives up the GDD lock to another
    member in the cluster by stopping and starting it, e.g:
    db2stop member 7
    db2start member 7?
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1 Mod 4 Fixpack 5 or higher                *
    ****************************************************************
    

Problem conclusion

  • First fixed in Db2 11.1 Mod 4 Fixpack 5
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT26370

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-09-20

  • Closed date

    2020-01-18

  • Last modified date

    2020-01-18

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • RB10 PSN

       UP

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Document Information

Modified date:
18 January 2020