PM81116: WMQ 7.0.1 SHARED STATUS ENTRY LEFT ORPHANED IF THE LAST CONVERSATION TO END IS NOT THE PRIMARY CONVERSATION

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• WMQ Client using shared conversation connect to the queue
  manager through the shared listener . An entry (row) is
  added into the shared channel status table CSQ.ADMIN_B_SCST .
  The shared status entry will be orphaned (not deleted)
  if the last conversation to end is not the primary
  conversation (the primary conversation has
  rriSession.pSharedStatus set, but the other conversations
  do not).
  When the last conversation ends, rriFreeSess is invoked
  with rriWork.pSess containing the address of the conversation
  being ended. If this is not the primary conversation, i.e.
  the first conversation that started, then the shared status
  entry will not be deleted from DB2.
  .
  Additional symptoms:
  - You see high CPU and delayed response from
     DISPLAY CHSTATUS() SHORT
    This may be done from the command line or the CSQOREXX panel.
    Additionally, the channel status count is high, e.g.
     CSQN205I   COUNT=  149862, RETURN=00000000, REASON=00000000
    or the CSQOLCAA List Channels panel has a status of
     149862 RUN
  - CSQX489E CSQXRESP Maximum instance limit 50 exceeded
    because the stop of the current channels is taking so long to
    complete (CSQXSTPC / CSQXSTOP / CSQXISTC / CSQMRM5F)
  

Local fix

• To prevent orphaned status entries, do one of the following:
  - Do not connect WMQ clients through a shared listener
    as advised at
    http://publib.boulder.ibm.com/infocenter/wmqv7/v7r0/topic/com
    .ibm.mq.csqsat.doc/zc10560_.htm
  - Specify SHARECNV(0) in the SVRCONN channel definition
    See the "Performance implications of sharing conversations
    on client-connection channels" at
    http://publib.boulder.ibm.com/infocenter/wmqv7/v7r0/topic/com.
    ibm.mq.csqzaf.doc/mi12240_.htm
  - Obtain a ++APAR from the support center.
  .
  These work-arounds will not clean up entries that were
  already orphaned.  There are a few clean-up options, but they
  could take a while like the DIS CHSTATUS did:
  .
  - Restart the CHIN. Deletion of the orphaned entries will take
    place while the CHIN is terminating, so there may be a delay
    before it can be started again.
  .
  - Run a SPUFI command:
     DELETE FROM CSQ.ADMIN_B_SCST WHERE CHLNAME='<channelname>'
     AND QSGNAME='<qsgname>';
    where <channelname> and <qsgname> are replaced as appropriate
    for your system.
    .
    There may be contention for the table.
    .
    You will get CSQX485E "Shared channel status error" and an
    FFST if a client ends after its entry has been deleted. These
    will not be a big impact if there are not too many active
    clients at the time.
  .
  - Delete and redefine the SVRCONN channel.  This option will
    have more overhead than the SPUFI option due to the
    involvement of the MSTR and CHIN jobs in doing the clean-up.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 *
  *                 Release 0 Modification 1 and Version 7       *
  *                 Release 1 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Orphaned shared channel status entries  *
  *                      cause performance problems.             *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When issuing a DISPLAY CHSTATUS(*) SHORT command there is a
  delayed response and high CPU in that qmgr.
  Similar performance problems when trying to STOP a SVRCONN
  channel which connects to clients over a shared listener.
  This is caused by a large number of orphaned entries in the
  shared channel status table CSQ.ADMIN_B_SCST.
  These have been created when a WMQ client connects to a qmgr
  by a channel which is capable of running multiple conversations
  (SHARECNV > 1 in the SVRCONN definition) over a shared
  listener (defined with INDISP (GROUP)).
  When the last conversation ends the shared status entry should
  be deleted, but it is not deleted if the last conversation to
  end is not the first conversation to be started.
  

Problem conclusion

• CSQXMMSA (CMQXRMSA at V710) has been updated to make sure the
  primary conversation points to the shared status entry.
  CSQXRCSI has been updated to use the primary conversation when
  deleting the shared status entry, if the pSharedStatus for the
  current session is null.
  010Y
  100Y
  CMQXRMSA
  CSQXRCSI
  CSQXRMSA
  

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:

  UK92011 UK92012

Modules/Macros

• CMQXRMSA CSQXRCSI CSQXRMSA
  

Fix information

• Fixed component name

  WMQ Z/OS V7

• Fixed component ID

  5655R3600

Applicable component levels

• R010 PSY UK92011

     UP13/04/04 P F304

• R100 PSY UK92012

     UP13/04/04 P F304

Fix is available

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