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LI71828: APPLICATION TRAPS DUE TO A RACE CONDITION BETWEEN THE DISCONNECTING APPLICATION AND THE EVENT MONITOR EDU.

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APAR status

  • Closed as program error.

Error description

  • This can occur in a EE or EEE environment but will need to have
    a connection event monitor running per node regardless of target
    activated either manual or automatically. During a deactivation
    of a database (implicitly via a connect reset or explicitly via
    a deactivate) a race condition between the disconnecting
    application or last application associated with a database and
    the event monitor EDU occurs. This exposes a hole in the
    serialization logic where the application can trap due to a bad
    dereference to memory freed by the event monitor EDU. The stacks
    resemble
    
    0        ossDumpStackTrace
    1        OSSTrapFile::dump
    2        sqlo_trce
    3        sqloEDUCodeTrapHandler
    4        __libc_sigaction
    5        sqm_db_resettable_data::id
    6        sqm_list_db_resettable_data::find_db
    7        sqm_resettable_data::find_db_rstd
    8        sqm_resettable_data::find_appl_rstd
    9        sqm_evmon_entity::adjust_conn_event
    

Local fix

  • A workaround if this problem is hit frequently is to ensure
    prior to deactivating a database, to manually shutdown all event
    monitors for connections then deactivate the database. This will
    ensure the application does not send a request to event monitors
    during a deactivate of a database as no event monitors will be
    running at that time.
    

Problem summary

  • Users Affected:
    ALL
    
    Problem Description:
    APPLICATION TRAPS DUE TO A RACE CONDITION BETWEEN THE
    DISCONNECTING APPLICATION AND THE EVENT MONITOR EDU.
    
    
    Problem Summary:
    APPLICATION TRAPS DUE TO A RACE CONDITION BETWEEN THE
    DISCONNECTING APPLICATION AND THE EVENT MONITOR EDU.
    

Problem conclusion

  • Problem was first fixed in Version 9.1 Fix Pack 3 (s070719)
    

Temporary fix

Comments

APAR Information

  • APAR number

    LI71828

  • Reported component name

    DB2 UDE ESE LIN

  • Reported component ID

    5765F4104

  • Reported release

    910

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2007-01-05

  • Closed date

    2008-12-04

  • Last modified date

    2008-12-04

  • 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 UDE ESE LIN

  • Fixed component ID

    5765F4104

Applicable component levels

  • R910 PSY

       UP

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Document Information

Modified date:
08 January 2022