PH17229: MQ Z V9 HIGH CPU CONSUMPTION DUE TO STORAGE FRAGMENTATION

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• rfxMatchQuery function would allocate storage to hold a list
  of subscription pointers, and would return that list to its
  caller. It is the responsibility of the calling function to
  ensure that the storage is freed when finished with.
  
  Most callers of rfxMatchQuery have appropriate logic to ensure
  that the storage is freed. However, a new function,
  rrmCheckSubs (first added at V904), doesn't free the
  subscription list.
  
  rrmCheckSubs is called repeatedly during cluster maintenance,
  which runs every hour. On a partial repository, it will be
  called once for each live object in the cluster cache, leaking
  x1A8 bytes each time it is called.
  
  Over time, these leaked control blocks result in storage
  fragmentation, increasing the CPU cost of all storage getmains
  in the chinit.
  

Local fix

• na
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 1 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Storage leak of x1A8 long blocks        *
  *                      during cluster maintenance.             *
  ****************************************************************
  During cluster maintenance blocks of storage of length x1A8
  bytes are allocated to hold a list of subscription pointers,
  however function rrmCheckSubs does not free them after use.
  Over time, these leaked control blocks result in storage
  fragmentation, increasing the CPU cost of all storage getmains
  in the chinit.
  

Problem conclusion

• Function rrmCheckSubs has been updated to free the subscription
  pointer storage blocks after use.
  

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:

  UI69086

Modules/Macros

• CMQXRMNT
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R100 PSY UI69086

     UP20/05/28 P F005

Fix is available

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