PM74826: ABEND5C6 00D401F1 CSQM1PGW +00000420 DURING POST GET WAIT

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Queue manager terminates with 00E50705 after GET processing
  fails. When attempting to post get waiters CSQM1PGW abends with
  ABEND5C6 00D401F1 which Level 3 found is due to the async
  consume processing being performed by the CHIN. A client
  channel has issued a browse against its target queue
  followed by a destructive MQGET with MQGMO_MSG_UNDER_CURSOR.
  As async consume is being used by the client, CSQMGETM
  is invoked to process the request and adds MQGMO_SET_SIGNAL
  to the MQGET request. This results in the handle being added
  to the get-wait chain. However, as MQGMO_MSG_UNDER_CURSOR
  is specified, none of the flags in mhnd.lflDMCGopts2 are set.
  The message is successfully retrieved from the queue, and
  then CSQMGET attempts to remove the handle from the get-wait
  chain. However, it suspends waiting for the get-wait chain
  latch, which is currently held by CSQM1PGW which has been
  invoked by commit processing as a new mesage has been put
  to the target queue. CSQM1PGW processes the handle from
  the client channel and detects that mhnd.lflDMCGopts2 is 0.
  This is an unexpected situation and hence the ABEND5C6 is
  issued. As CSQM1PGW is running on a commit SRB and is
  holding a latch at the time of the abend, the queue-manager
  terminates with 00E50705. CSQM1PGW needs to allow for a
  handle with mhnd.lflDMCGopts2 being set to 0 in the case
  where mhnd.fGMsgUCursor or mhnd.fGBrUCursor are on.
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of WebSphere MQ for z/OS Version 7 *
  *                 Release 0 Modification 1 and Release 1       *
  *                 Modification 0.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: The QMGR abends with 00D401F1 when an   *
  *                      application tries to put a message to   *
  *                      a queue which is in use by an           *
  *                      application doing browse messages       *
  *                      followed by a get call with             *
  *                      MQGMO_MSG_UNDER_CURSOR.                 *
  *                      A consequence of this abend happening   *
  *                      could be abends including 00E50013,     *
  *                      00E50044 and 00E50705, as well as       *
  *                      queue manager termination.              *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  An application using the internal API (such as the MQ
  Async-Consume feature) is browsing a queue followed by a get
  with the MQGMO_MSG_UNDER_CURSOR option.
  In CSQMGET, the application will put and remove its handle from
  the get-wait chain, whilst holding the MPDO latch. When trying
  to get the latch before removing the handle from the chain, the
  application is suspended (waiting for the latch).
  In parallel another application is putting a message to the same
  queue. As part of the commit processing, the get-wait chain is
  scanned whilst holding the MPDO latch (causing the first
  application to get suspended). The handle of that application is
  found, and the options are checked. They do not match the
  expected value, causing the 00D401F1 abend to be issued, leaving
  the unit of work in flight.
  Depending on the type of application that does the put, IMS,
  CICS, batch etc. any abends following the 00D401F1 may vary.
  

Problem conclusion

• The code was changed to avoid creating the condition by the use
  of the internal API, preventing the 00D401F1 from happening.
  010Y
  100Y
  CSQMGETM
  CSQM1PGW
  

Temporary fix

• *********
  * HIPER *
  *********
  

Comments

APAR Information

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

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

  UK83936 UK83937

Modules/Macros

• CSQMGETM CSQM1PGW
  

Fix information

• Fixed component name

  WMQ Z/OS V7

• Fixed component ID

  5655R3600

Applicable component levels

• R010 PSY UK83936

     UP13/01/16 P F301 Ž

• R100 PSY UK83937

     UP13/01/16 P F301 Ž

Fix is available

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