PI74030: WMQ: EXCESSIVE STORAGE ALLOCATION AND FREE OPERATIONS FOR SVRCONN CHANNELS WITH A SHARECNV VALUE GREATER THAN ZERO

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Excessive storage allocation and free operations for SVRCONN
  channels with a SHARECNV value greater than zero
  .
  Additional Symptom(s) Search Keyword(s):
  CHIN trace has many CSQXGETS calls obtaining 688 or 0x2B0 bytes
  for rstSTREAMQUEUE storage, which has an eyecatcher of RSTQ .
  .
  MQOPEN MQCLOSE performance
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:                                              *
  * All users of IBM MQ for z/OS Version 9 Release 0             *
  * Modification 0.                                              *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  * Increased CPU usage in Chinit when using SVRCONNs with       *
  * SHARECNV greater than zero with workload that frequently     *
  * opens and closes queues.                                     *
  ****************************************************************
  * RECOMMENDATION:                                              *
  * When a SVRCONN channel is using shared conversations and is  *
  * frequently opening and closing queues, additional storage    *
  * for control blocks is regularly obtained and released. While *
  * this is correct behavior, applications that perform a large  *
  * number of queue open and close operations may find that the  *
  * additional overhead of this storage management begins to     *
  * have an impact on Chinit performance exhibiting high CPU in  *
  * IGVGPVT.                                                     *
  ****************************************************************
  

Problem conclusion

• Some control blocks associated with opening and closing queues
  have been moved to z/OS cellpools to improve efficiency.
  

Temporary fix

Comments

APAR Information

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

  PI73537

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

  UI44033

Modules/Macros

• CMQXRSTF CSQXJST  None
  

Fix information

• Fixed component name

  MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R000 PSY UI44033

     UP17/02/08 P F702

Fix is available

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