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IT35764: EXTENT MOVER CAN HANG WAITING FOR SQLO_LT_SQLB_POOL_CB__READLOTCH WHILE HOLDING SQLO_LT_SQLB_EXTENT_DESC__EXTENTLATCH

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APAR status

  • Closed as program error.

Error description

  • Note that in releases >= 11.1.4.4 the extentLatch was renamed to
    extentLotch and this APAR is still applicable.
    
    This is a 3-way dead latch between the Extent Mover (spawned by
    running ALTER TABLESPACE .. [REDUCE MAX | LOWER HIGH WATER MARK
    | REDUCE <value>]), a Page Cleaner, and a 3rd EDU (of any
    description) that is requesting SQLO_LT_SQLB_POOL_CB__readLotch
    in exclusive mode. The dead latch looks like the following:
    
    1. Page Cleaner is holding SQLO_LT_SQLB_POOL_CB__readLotch in
    shared mode and requesting SQLO_LT_SQLB_EXTENT_DESC__extentLatch
    in shared mode with the following stack:
    
    getConflict
    sqlbFindAndLatchExtent (name changed to sqlbFindAndLotchExtent
    in releases >= 11.1.4.4)
    sqlbCommonWriteSetup
    sqlbClnrAsyncWriteSetup
    sqloDispatchNBlocks
    sqlbClnrWriteSerializedPages
    sqlbClnrWritePages
    
    2. Extent Mover is holding SQLO_LT_SQLB_EXTENT_DESC__extentLatch
    in exclusive mode and requesting SQLO_LT_SQLB_POOL_CB__readLotch
    in shared mode with one of the following stacks:
    
    getConflict
    getLatchOnly
    sqlbMoveHighestExtent
    sqlbLockAndMoveExtents
    sqlbExtentMovementEntryPoint
    
    getConflict
    getLatchOnly
    sqlbCommonWriteSetup
    sqlbWritePage
    sqlbUnfixPage
    sqlbMoveHighestExtent
    sqlbLockAndMoveExtents
    sqlbExtentMovementEntryPoint
    
    getConflict
    getLatchOnly
    sqlbCommonWriteSetup
    sqlbWritePage
    sqlbUnfixPage
    sqldUnFixFILE_INFO
    sqldUpdateRow
    sqldoupd
    sqlbMoveHighestExtent
    sqlbLockAndMoveExtents
    sqlbExtentMovementEntryPoint
    
    3. A 3rd EDU is requesting SQLO_LT_SQLB_POOL_CB__readLotch in
    exclusive mode. For example BACKUP:
    
    getConflict
    getLatchOnly
    sqlbLatchPoolForReadWrite
    sqlbTestSetDatapoolState
    sqlubBuildAppTbsp
    sqlubcka
    sqlubcka_route_in
    

Local fix

  • Install latest fix pack.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * N/A                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Fix target is 11.1.4.7                                       *
    ****************************************************************
    

Problem conclusion

  • Fix target is 11.1.4.7
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT35764

  • 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

    2021-02-02

  • Closed date

    2022-04-18

  • Last modified date

    2022-04-18

  • 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 PSY

       UP

[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSEPGG","label":"DB2 for Linux- UNIX and Windows"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"11.1","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
04 May 2022