IV47968: MQ APPLICATION LIBRARIES HANG IN FORKED CHILD PROCESS WHEN EXEC OF AMQZXMSG0 FAILS

WebSphere MQ V7.5 Fix Pack 7.5.0.3
WebSphere MQ V7.0 Fix Pack 7.0.1.12
Fix Pack 7.1.0.5 for WebSphere MQ V7.1

APAR status

• Closed as program error.

Error description

• WebSphere MQ uses a program called 'amqxmsg0' to write to the
  Websphere MQ error log when the MQ error logging function
  encounters error when writing to the MQ error log. 'amqxmsg0'
  is spawned using fork and exec system calls by MQ
  libraries from within WebSphere MQ Applications. In some
  circumstances, the spawning of amqzxmsg0 might hang with the
  following stack trace.
  
  Forked child process:
  
  ....
  xeeCallWriteMsgProgram () from /opt/mqm/lib64/libmqe_r.so
  xcsDisplayMessage () from /opt/mqm/lib64/libmqe_r.so
  xcsDisplayMessageForSubpoolError () from .../lib64/libmqe_r.so
  rrxReportError () from /opt/mqm/lib64/libmqe_r.so
  ....
  main ()
  
  Application(Parent process)
  
  waitpid () from /lib64/libpthread.so.0
  xeeCallWriteMsgProgram () from /opt/mqm/lib64/libmqe_r.so
  xcsDisplayMessage () from /opt/mqm/lib64/libmqe_r.so
  xcsDisplayMessageForSubpoolError () from .../lib64/libmqe_r.so
  rrxReportError () from /opt/mqm/lib64/libmqe_r.so
  ....
  main ()
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users running MQ applications having complex C++ class
  destructors and atexit handlers
  
  Platforms affected:
  All Unix
  
  ****************************************************************
  PROBLEM SUMMARY:
  This problem occurred because WebSphere MQ used the exit system
  call instead
  of the _exit function when spawning the amqxmsg0 process.
  

Problem conclusion

• WebSphere MQ has been modified to use the _exit function instead
  of the exit
  system call when spawning the amqxmsg0 process.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v7.0       7.0.1.12
  v7.1       7.1.0.5
  v7.5       7.5.0.3
  
  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

  WMQ AIX V7

• Fixed component ID

  5724H7221

Applicable component levels

• R701 PSY

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