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PI78282: ORPHAN CONNECTION/THREADS REMAIN ACTIVE AT REMOTE DB2 LOCATIONS AFTER A DB2 REQUESTER DRDACBF BOUND APPLICATION TERMINATES

A fix is available

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APAR status

  • Closed as program error.

Error description

  • See PI78280 for DB2 11 for z/OS.
    DB2 REQUESTER APPLICATION WHICH USES DRDACDF BOUND PACKAGES AND
    REFERENCES DB2 REMOTE LOCATIONS MAY TERMINATE WITHOUT PROPERLY
    TERMINATING CONNECTIONS TO THE REMOTE LOCATIONS. ORPHAN
    CONNECTION/THREADS AT THOSE DB2 REMOTE LOCATIONS WILL REMAIN
    ACTIVE HOLDING LOCKS, THREAD SLOTS, ETC., WHICH WOULD THEN LEAD
    TO UNPREDICTABLE MESSAGES AND/OR APPLICATION FAILURES BEING
    ISSUED AT THE REMOTE DB2 LOCATIONS.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * All Distributed Data Facility (DDF) users.                   *
    * Specifically those who are planning to or                    *
    * are using z/OS applications which use                        *
    * packages bound with DBPROTOCOL(DRDACBF).                     *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * -DISPLAY LOCATION DETAIL command                             *
    * shows ATT=CBF, T=R (requester)                               *
    * connections to another DB2 location,                         *
    * but -DISPLAY THREAD command does                             *
    * not show any threads accessing the                           *
    * remote location.                                             *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Apply corrective PTF when available                          *
    ****************************************************************
    DB2 12 supports a capability called Cursor Block Fetch
    (CBF) which is activated by a z/OS DB2 requester application
    utilizing package(s) bound with the DBPROTOCOL(DRDACBF).
    Each read-only cursor operation performed by the application
    against another DB2 location, running at least V11 NFM, is
    processed on its own connection to the remote DB2 location.
    Once a cursor operation at the server is exhausted or the
    application chooses to close the cursor before retrieving all
    the rows of the query, the DB2 requester attempts to terminate
    the connection to the remote location.  However, due to an
    internal DB2 logic error, the attempt to terminate the
    connection may not be processed correctly and no error
    indication is returned to the requesting z/OS application.
    Thus, once the requesting application thread terminates, a
    -DISPLAY LOCATION DETAIL command report may show that ATT=CBF,
    T=R connections still exist against the remote DB2 location
    even though the -DISPLAY THREAD(*) DETAIL command report
    suggests that no threads are associated to the connections.
    These connections are deemed to be orphan connections because
    no thread is currently using them and either a recycle of the
    DDF requester, or a Vary TCPIP Drop (V TCPIP,,DROP) command
    against each connection, will eliminate them.
     Note: While the connections remain active in the DB2
      requester subsystem, corresponding connections will also
      be active in the serving DB2 subsystem.  These server
      connections will also be associated to active DBATs.
      These DBATs may therefore hold resources for an extended
      period of time (until the connections are closed or the
      DBATs are canceled) which may lead to various unpredictable
      symptoms at the server location.
    

Problem conclusion

  • DB2 12 has been changed to correctly process the termination
    of CBF connections to remote DB2 locations.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI78282

  • Reported component name

    DB2 OS/390 & Z/

  • Reported component ID

    5740XYR00

  • Reported release

    C10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-03-15

  • Closed date

    2017-04-10

  • Last modified date

    2017-05-01

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

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

    UI46302

Modules/Macros

  • DSNLCCNR
    

Fix information

  • Fixed component name

    DB2 OS/390 & Z/

  • Fixed component ID

    5740XYR00

Applicable component levels

  • RC10 PSY UI46302

       UP17/04/25 P F704

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.



Document information

More support for: DB2 for z/OS

Software version: C10

Reference #: PI78282

Modified date: 01 May 2017


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