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IC81190: DB2 LOGGER I/O CONTENTION CAUSING PERFORMANCE ISSUES

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • If LOGBUFSZ database configuration parameter is set to a high
    value, then contention can be seen during db2 logging since
    db2ReadLog API would be called repeatedly which can stress
    memory and cause performance issues on busy systems.
    
    db2pd -latches output will show db2 loggers waiting for the
    following latch:
    
    Latches:
    Address            Holder     Waiter     Filename
    LOC        LatchType
    No latch holders.
    0x07000000700003E0 0          1135675    Unknown              45
    SQLO_LT_SMemPool__MemLatchType__latch
    0x07000000700003E0 0          1137474    Unknown              45
    SQLO_LT_SMemPool__MemLatchType__latch
    0x07000000700003E0 0          1138759    Unknown              45
    
    0x0700000040027300 0          2316429    Unknown
    189        SQLO_LT_SQLP_APPEND_LREC_CB_IO__logIOCompLatch
    0x0700000040027300 0          102817     Unknown
    189        SQLO_LT_SQLP_APPEND_LREC_CB_IO__logIOCompLatch
    
    The stack dumps for the db2logger process may look as follows:
    
    0x09000000000EEEF8 thread_wait + 0x98
      0x090000000DAB775C getConflictComplex__17SQLO_SLATCH_CAS64FCUl
    + 0x3DC
      0x090000000DAB7ABC getConflict__17SQLO_SLATCH_CAS64FCUl + 0xC8
      0x090000000DAB7BA0 getConflict__17SQLO_SLATCH_CAS64FCUl@glueF9
    + 0x74
      0x090000000DA00FCC
    sqlpProcessWakeUpList__FP9SQLP_DBCBP22SQLP_APPEND_LREC_CB_WA +
    0x20
      0x090000000DB3AA10 sqlpgasn2__FPcUi + 0x100
      0x090000000DC8FBB8 sqloEDUEntry + 0x36C
    

Local fix

  • As a temporary workaround, you may try reduce LOGBUFSZ a little
    and verify. The size has to be chosen carefully as too
    small
    value can cause performance impacts as well for a busy system.
    Hence, the value needs to be carefully chosen as per workloads
    on the system.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All users on DB2 v97 FP5 and earlier                         *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 v97 FP6                                       *
    ****************************************************************
    

Problem conclusion

  • First Fixed in DB2 v97 FP6
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC81190

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    970

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-02-02

  • Closed date

    2012-06-26

  • Last modified date

    2012-07-12

  • 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

  • R970 PSY

       UP



Document information

More support for: DB2 for Linux, UNIX and Windows

Software version: 9.7

Reference #: IC81190

Modified date: 12 July 2012