PH15068: IBM MQ Z/OS:ABN=5C6-00C92200 LOC=CSQILPLM.CSQIMPU2

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• If two tasks are both browsing and retrieving messages from a
  queue just as the queue goes empty, it's possible for one of
  the tasks to complete the operation without correctly clearing
  its allocation locks for the page, causing the following abend
  to occur some later time when the page is reused:
  ABN= 5C6-00E7014F
  ,LOC=CSQXADPM.CSQXADPM
  
  Once an orphaned lock has been created, it's possible that
  applications using any queue on the same pageset may be
  impacted as the lock is held at the pageset level. This means
  that other applications sharing the pageset (but not the
  problematic queue) can  also be impacted.
  
  Additional Symptom(s) Search Keyword(s):
  ABN= 5C6-00E7014F,
  ,LOC=CSQXADPM.CSQXADPM
  

Local fix

• By no longer having multiple threads attempting to access the
  same pages related to a single queue, the problem should be
  avoided.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 0 Modification 0 and Release 1       *
  *                 Modification 0.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: When two applications browse a shared   *
  *                      queue concurrently messages may be      *
  *                      left locked.                            *
  *                      When the record that contained the      *
  *                      message is subsequently reused, abend   *
  *                      5C6-00C92200 occurs in CSQIMPU2 due     *
  *                      to the orphaned lock.                   *
  ****************************************************************
  When two applications browse and get messages from a shared
  queue concurrently specific timing situations can result in the
  cursor.locked field within the browse cursor being reset without
  the associated message record lock being freed immediately.
  As there is now no indication that a lock is held further browse
  processing may not free the lock either, and it can remain set
  until the application ends.
  The residual record lock information for the message can cause
  subsequent processing by this or another application sharing the
  queue to fail if an attempt is made to put a message to the same
  record/page/PSID as the allocation lock appears to be already
  set.
  

Problem conclusion

• Browse lock processing has been changed for the reported
  problem to prevent Cursor.Locked being reset invalidly.
  

Temporary fix

Comments

APAR Information

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

  PH13499

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

  UI65150 UI65151

Modules/Macros

• CSQIMGE1 CSQIMGE3
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R000 PSY UI65150

     UP19/09/26 P F909 ¢

• R100 PSY UI65151

     UP19/09/26 P F909 ¢

Fix is available

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