PM69557: HIGH CPU CAUSED BY LOOP IN FMIBUILDSTREAMSSUPPORTED DUE TO DUPLCIATE MESSAGES ON QUEUE.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• The customer experienced high amount of CPU when
  starting up on of their channel initiator
  address space.
  .
  The high CPU is caused by a loop in
  fmiBuildStreamsSupported. It looks as though
  this is caused by duplicate messages on the
  SYSTEM.HIERARCHY.STATE queue.
  .
  29BE54B0 C5D44BC2 D9D6D2C5 D94BD7D9 C9D4C1D9 |EM.BROKER.PRIMAR|
  29BE54C0 E84BE2E3 C1E3C500 6CA20000 E2E8E2E3 |Y.STATE.%s..SYST|
  29BE54D0 C5D44BC8 C9C5D9C1 D9C3C8E8 4BE2E3C1 |EM.HIERARCHY.STA|
  29BE54E0 E3C54040 40404040 40404040 40404040 |TE              |
  .
  29BE54C0 E84BE2E3 C1E3C500 6CA20000 E2E8E2E3 |Y.STATE.%s..SYST|
  29BE54D0 C5D44BC8 C9C5D9C1 D9C3C8E8 4BE2E3C1 |EM.HIERARCHY.STA|
  29BE54E0 E3C54040 40404040 40404040 40404040 |TE              |
  29BE54F0 40404040 40404040 40404040 00000000 |            ....|
  .
  Other symptom:
  In the CHININT trace:
  .
  SYSH Exit 02930334 18:09:20. fmiGetStreamSupportedTopicString
  Field 01  Block: 29CC0AF4
     TCB...... 00ACBE88  DPRO..... 29CB7000
     Conv..... 00000000  Primary.. 00000000
  .
  In the SUMTRACE:
  .
  CLKC Events:
  
  ASID Jobname  SRB/TCB      Clkc PSW
  ---- -------- -------- -----------------
  007A MQNSCHIN 00ACBE88 078D5000 A9327AC8
  007A MQNSCHIN 00ACBE88 078D4000 A9327A4A
  007A MQNSCHIN 00ACBE88 078D4000 A9327A4A
  007A MQNSCHIN 00ACBE88 078D4000 A9327A4A
  007A MQNSCHIN 00ACBE88 078D4000 A9327A4A
  007A MQNSCHIN 00ACBE88 078D4000 A9327A4A
  007A MQNSCHIN 00ACBE88 078D4000 A9327A48
  007A MQNSCHIN 00ACBE88 078D5000 A932708C
  Additional symptoms:
   CHIN hang at shutdown in fsiAllocate / xcsAllocateMemBlock
  waiting for a mutex.
  .
  High CPU in the TCB associated with load module CSQXFSTR (the
  Pub/Sub Daemon)
  

Local fix

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: Loop in fmiBuildStreamsSupported when   *
  *                      starting the channel initiator with     *
  *                      PSMODE(ENABLED), leading to high CPU    *
  *                      utilisation.                            *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  While starting up, the pubsub daemon called fsxStart to start
  the streams specified in SYSTEM.QPUBSUB.QUEUE.NAMELIST. fsxStart
  began processing records from SYSTEM.HIERARCHY.STATE, but
  encountered an error while doing so (for example, due to the
  queue manager being quiesced).
  A problem in how this error was handled caused duplicate records
  to be written for any streams which had not yet had their record
  on SYSTEM.HIERARCHY.STATE processed and allowed the daemon to
  start up in an invalid state (without the dummy stream running).
  This invalid state led to the loop occurring the next time
  fmiBuildStreamSupported was called.
  On subsequent restarts the duplicate records on
  SYSTEM.HIERARCHY.STATE caused errors in fsxStart, leading to
  repeated occurrences of the loop.
  

Problem conclusion

• fsxStart is changed to handle the initial error correctly, so
  that the error is reported and the daemon is prevented from
  continuing to start up in an invalid state.
  010Y
  100Y
  CMQXFSXA
  

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:

  UK81236 UK81237 IV26834

Modules/Macros

• CMQXFSXA
  

Fix information

• Fixed component name

  WMQ Z/OS V7

• Fixed component ID

  5655R3600

Applicable component levels

• R010 PSY UK81236

     UP12/09/20 P F209 Ž

• R100 PSY UK81237

     UP12/09/20 P F209 Ž

Fix is available

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