PH49498: MQ CHINIT ABENDS BUT DOES NOT END ( HANG ) WHEN DISPATCHER PROCESS DIES OR IS KILLED

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• When the dispatcher process is killed / terminated, the CHINIT
  throws this error
  
  +CSQX112E cpf CSQXDISP Dispatcher process error, TCB=XXXXXXXX
   reason=EC6000-0000FF0F
  BPXP023I THREAD nnnnnnnnnnnnnnnn, IN PROCESS nnnnnnnn, WAS
   TERMINATED BY SIGNAL SIGTERM, SENT FROM THREAD
   nnnnnnnnnnnnnnnn, IN PROCESS 1, UID 0, IN JOB BPXOINIT.
  
  and takes a dump, as expected.
  
  The CHINIT, being in an unrecoverable state, begins to shutdown.
  
  Eventually, it reaches somewhere around this point
  
  +CSQT976I cpf CSQXDPSC Distributed Pub/Sub Controller has
  stopped
  +CSQX953I cpf CSQXJST Distributed Pub/Sub Offloader task
  detached
  
  where it hangs and sits there indefinitely.
  
  In this limbo state, it is possible to bring up a new CHINIT,
  that is able to start up normally and run normally. However,
  this hung CHINIT will still stay as "executing" and does not
  come down until killed.
  
  The problem persisted even with PH39154 / PTF UI81039 applied.
  
  IBM MQ Development: z/OS Service team found that after the
  dispatcher was ended, the CHINIT supervisor task detected that
  a dispatcher had terminated, and initiated CHINIT shutdown. As
  part of this shutdown processing, the supervisor task called
  CSQXSPRT to release all of the supervisor acquired resources.
  The CHINIT job step task waits for the attached subtasks to
  end, however in this instance the CHINIT XSMF task wasn't told
  to end by the supervisor because the supervisor abends when
  trying to interact with the terminated dispatcher. This results
  in the job step task waiting for the XSMF task to end, which
  won't be ended and this therefore results in the hang.
  .
  Additional keywords and symptoms:
  ABENDEC6 0000FF09 for BPXP023I with SIGKILL
  https://www.ibm.com/docs/en/zos/2.5.0?topic=31-bpxysigh-signal-c
  onstants
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 2 Modification 0 and Release 3       *
  *                 Modification 0.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Termination or an abend in a dispatcher *
  *                      TCB can cause the CHINIT to hang        *
  *                      indefinitely while shutting down.       *
  *                                                              *
  *                      This extends the fixes made in PH39154  *
  *                      / PTF UI81039, and prevents a hang when *
  *                      channels are active at the time of the  *
  *                      abend.                                  *
  ****************************************************************
  The XSMF task is attached and detached by the job step task
  on instruction of the supervisor task. In the event that the
  supervisor abends, the job step task will never be signalled to
  detach the XSMF task but will be waiting on it to end. This
  causes the channel initiator to hang on shutdown.
  

Problem conclusion

• When the channel initiator is stopping and instructs all active
  TCBs to terminate, a flag is now set to avoid abending if a TCB
  has already stopped or been cancelled. This allows the channel
  initiator to stop gracefully in the problem case.
  

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:

  UI90168 UI90169

Modules/Macros

• CSQXSCAN
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R200 PSY UI90169

     UP23/02/04 P F302

• R300 PSY UI90168

     UP23/02/04 P F302

Fix is available

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