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IC80710: PERFORMING REMOTE APPLICATION SNAPSHOTS CONCURRENTLY MAY CAUSE THE INSTANCE HUNG

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • In a federated DB2 database server environment, if multiple
    users or clients are collecting remote application snapshots
    concurrently, it may sometimes cause a dead latch in the DB2
    server which may effectively lead to the instance hanging.
    
    When the instance is hung, the stacks and the latches of the
    two agents may look like below:
    
    1) the agent 1 is holding the master application latch -
    SQLO_LT_sqeApplication__masterAppLatch, but waiting on the
    remote latch - SQLO_LT_sqlmon_dbcb__xlatch_remote_list.
    
    thread_waitlock
    sqloXlatchConflict
    sqm_snap_appl_remote
    sqlmonssagnt
    sqlmonssbackend
    sqlesrvr
    sqleMappingFnServer
    sqlerKnownProcedure
    sqlerCallDL
    
    2) While the agent 2 is holding the remote latch -
    SQLO_LT_sqlmon_dbcb__xlatch_remote_list, but is waiting on the
    master application latch -
    SQLO_LT_sqeApplication__masterAppLatch.
    
    thread_waitlock
    sqloXlatchConflict
    estim_appl_remote_snap_sz
    sqlmonszagnt
    sqlmonszbackend
    sqlesrvr
    sqleMappingFnServer
    sqlerKnownProcedure
    sqlerCallDL
    
    
    Thus there is a dead latch situation between these two agents.
    As these agents may also be holding other latches, such as the
    database latch, the application service latch, etc., this may
    eventually cause the instance to appears as hung, that is,
    terminating an existing connection or new database connections
    may get hung on these latches. The only way to get out of this
    hang is to recycle the db2 instance.
    

Local fix

  • 1. Set database manager configuration variable FEDERATED to NO.
    Please note that this will disable the federation setup and will
    not allow connection to data sources through the federation
    server.
    
    2. Recycle the instance to resolve the hang and avoid collection
    of remote application snapshots as much as possible. Please note
    that some tools such as db2top may collect such snapshots
    undercover, avoid to run these tools if possible.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * Users in a federated DB2 database server environment where   *
    * multiple users or clients are collecting remote application  *
    * snapshots concurrently.                                      *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 Version 9.7 Fix Pack 6 or newer               *
    ****************************************************************
    

Problem conclusion

  • Problem was first fixed in Version 9.7 Fix Pack 6
    

Temporary fix

  • See above Local Fix
    

Comments

APAR Information

  • APAR number

    IC80710

  • 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

    2012-01-09

  • Closed date

    2012-06-18

  • Last modified date

    2013-05-27

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

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

    IC81192 IC84305

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R970 PSN

       UP



Document information

More support for: DB2 for Linux, UNIX and Windows

Software version: 9.7

Reference #: IC80710

Modified date: 27 May 2013