IT29088: Partial FDC record written by amqzlaa0 process followed by hang or abend of that process

APAR status

• Closed as program error.

Error description

• On the IBM MQ Appliance, a failure data capture (FDC) record is
  generated by the amqzlaa0 process in response to an error
  condition, but only the first 8 lines of the record header are
  visible in the output .FDC file.
  
  This partial record is due to a secondary memory exception while
  writing the FDC record, and the process or thread then hangs or
  abends.
  
  The 8 lines written are similar to the following:
  +---------------------------------------------------------------
  --------------+
  |                                       |
  | WebSphere MQ First Failure Symptom Report                  |
  | =========================================                  |
  |                                       |
  | Date/Time     :- Tue Aug 27 2019 03:04:17 GMT              |
  | UTC Time     :- 1566875057.086421                   |
  | UTC Time Offset  :- 0 (GMT)                       |
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of MQ code (running in client or server installations) in
  the unlikely event that a memory exception is generated within
  heap management routines (a possible cause of this is corruption
  of the heap memory).
  
  
  Platforms affected:
  AIX, HP-UX Itanium, IBM iSeries, Linux on Power, Linux on
  x86-64, Linux on x86, Linux on zSeries, Solaris SPARC, Solaris
  x86-64
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  To obtain information about the operating system, the MQ signal
  handler had called the C library function fopen() marked as
  non-async-signal-safe.  This caused a secondary memory
  exception, whose signature was a partially-written FDC record.
   (Also note that a shortage of disk space in /var/mqm/errors is
  another reason for partially-written FDC records).
  

Problem conclusion

• The call to fopen() to obtain information about the operating
  system has been moved to earlier in the life of the program, so
  that it is not called from the signal handler.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v8.0       8.0.0.13
  v9.0 LTS   9.0.0.8
  v9.1 CD    9.1.4
  v9.1 LTS   9.1.0.4
  
  The latest available maintenance can be obtained from
  'WebSphere MQ Recommended Fixes'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
  
  If the maintenance level is not yet available information on
  its planned availability can be found in 'WebSphere MQ
  Planned Maintenance Release Dates'
  http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
  ---------------------------------------------------------------
  

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:

Fix information

• Fixed component name

  IBM MQ APPL M20

• Fixed component ID

  5725Z0900

Applicable component levels