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IT33836: PURESCALE MEMBER MIGHT HANG WAITING FOR SQLO_LT_SQLB_BPD__BPDLATCH_SX WHILE IN SQLBGBUPGRADELATCHFROMSHAREDURINGWAR

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APAR status

  • Closed as program error.

Error description

  • Under certain timing conditions a hang/deadlatch can occur after
    an agent has sent modified pages to the Group Buffer Pool (GBP).
    An agent (A) will be holding one or more page latches
    (SQLO_LT_SQLB_BPD__bpdLatch_SX) in shared (S) mode, and
    attempting to upgrade a page latch to exclusive (X) mode in
    function sqlbgbUpgradeLatchFromShareDuringWAR. This agent will
    have a stack similar to the following:
    
    getConflictComplex
    getConflict
    sqlbgbUpgradeLatchFromShareDuringWAR
    sqlbgbWARM_PostProcessing
    sqlbgbWARM
    
    Meanwhile, another agent (B) will be holding (in S or X mode)
    the page latch agent A is attempting to latch. At the same time
    agent B will be attempting to latch in X mode one of the page
    latches that is held in S mode by agent A.
    
    Agent B might have a stack similar, but not limited to, the
    following:
    
    getConflictComplex
    getConflict
    sqlbFindPageInBPOrSim
    sqlbfix
    

Local fix

  • The hang/deadlatch is contained within a member. Killing the
    member and allowing it to recover will resolve the hang.
    
    A workaround to prevent the hang is to do the following:
    db2set DB2_HIGH_CONCURRENCY_WAR=OFF. Each member would have to
    have db2stop and db2start run for this to take effect. Note that
    this will have a negative performance impact for heavy insert,
    update, or delete workloads.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * all                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1.4.6 or higher                            *
    ****************************************************************
    

Problem conclusion

  • Upgrade to Db2 11.1.4.6 or higher
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT33836

  • 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

    2020-08-07

  • Closed date

    2021-03-31

  • Last modified date

    2021-03-31

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

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

    IT33863

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1"}]

Document Information

Modified date:
01 April 2021