PI40890: QAPPLY ABENDS0C4 POSSIBLE WHEN A DEADLOCK OCCURS WHEN QAPPLY IS PERFORMING A QUERY OF SYSIBM.SYSTABLES.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Qapply ABENDS0C4 is possible when Q Apply performs a query of
  SYSIBM.SYSTABLES and a deadlock takes place.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: 1- Q Apply                                   *
  *                 2- Q Capture                                 *
  *                 3- Q Apply, Q Capture                        *
  *                 4- SQL Capture                               *
  *                 5- Q Apply                                   *
  ****************************************************************
  * PROBLEM DESCRIPTION: 1- Q Apply failed to stop when the      *
  *                      control table IBMQREP_DONEMSG was       *
  *                      inaccessible.  Browser threads stop as  *
  *                      expected, but the program continues to  *
  *                      run.                                    *
  *                      2- When MQ is terminated (STOP QMGR     *
  *                      command) without force, neither         *
  *                      QCapture nor MQ terminates.             *
  *                      3- Q Replication programs querying      *
  *                      SYSIBM.SYSTABLES catalog for            *
  *                      determining table structure do not      *
  *                      handle  deadlocks correctly. This may   *
  *                      lead to internal errors or 0C4 abend.   *
  *                      4- 1. The capture program may dump      *
  *                      (OC4) when converting a table or        *
  *                      column name from UTF-8 to EBCDIC        *
  *                      during DDL log record processing.       *
  *                      Specifically, this occurs if the        *
  *                      conversion using UCS returns an error   *
  *                      and ICU is attempted to be used. 2.     *
  *                      The capture program stops with          *
  *                      conversion error if column or table     *
  *                      name from DDL operations cannot be      *
  *                      converted from UTF-8 to EBCDIC. Such    *
  *                      tables or columns cannot be subscribed  *
  *                      to.                                     *
  *                      5- ASN7618I message contains a wrong    *
  *                      SQLCODE when target is the stored       *
  *                      procedure.                              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  1- The expected behavior is that the Q Apply program would
  stop. However, the program kept running but performed no action
  and the operator is forced to stop it manually.
  2- QCapture was not running MQ operations with the
  FAIL_IF_QUIESCING flag like it should, and the admin thread was
  not communicating its MQ connection problem to the worker
  thread.
  3- Q Apply and Q Capture programs query SYSIBM.SYSTABLES
  catalog for determining table structure, such as when starting
  a subscription or replicating table alters. If there are
  deadlocks or lock timeouts while querying SYSTABLES, these do
  not get handled correctly leading to reporting of internal
  errors or it may lead to an 0C4 abend.
  4- 1. The capture program does not handle the switch from UCS
  to ICU correctly that may result in a dump (OC4) if conversion
  errors occur in UCS. 2. The capture program ignores any
  conversion errors during DDL processing as such objects cannot
  be subscribed.
  5- When a subscription's TARGET_TYPE is set to 5, Q Apply does
  not fill meaningful values in SQLCODE, SQLSTATE and Reason Code
  in ASN7618I.
  

Problem conclusion

• 1- When the IBMQREP_DONEMSG table is inaccessible, the program
  will stop.
  2- The code changes make sure that QCapture gracefully exits
  when MQ is quiescing, allowing all three processes to exit.
  3- Q Replication programs now handle deadlocks correctly when
  querying SYSIBM.SYSTABLES catalog tables.
  4- The capture program has been fixed.
  5- The problem is fixed.
  

Temporary fix

Comments

APAR Information

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

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

  UI28355 UI28356 UI28357 UI28358

Modules/Macros

•    ASNACMD  ASNADMSP ASNAPPLY ASNCAP   ASNCCMD
  ASNCLPAP ASNCLPCL ASNCLPCM ASNCLPCO ASNCLPMS ASNCLPQA ASNMCMD
  ASNMIG8  ASNMON   ASNPLXFY ASNQACMD ASNQAHKT ASNQAPP  ASNQAROW
  ASNQBRWZ ASNQCAP  ASNQCCMD ASNQDEP  ASNQEXRP ASNQMFMT ASNQXFMT
  ASNRBASE ASNSQLCZ ASNTDIFF ASNTDSP  ASNTRC   ASN2BASE ASN2SQLZ
  

Fix information

• Fixed component name

  WS REPLICATION

• Fixed component ID

  5655L8800

Applicable component levels

• RA10 PSY UI28355

     UP15/06/17 P F506

• RA11 PSY UI28356

     UP15/06/18 P F506

• RA12 PSY UI28357

     UP15/06/17 P F506

• RA13 PSY UI28358

     UP15/06/18 P F506

Fix is available

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