IC77278: DELAYS SEEN WHEN A CLIENT APPLICATION IS CONNECTED TO MULTIPLE QUEUE MANAGERS AND ONE OF THEM IS ENDED

WebSphere MQ v7.0.1.7 Hypervisor for AIX
WebSphere MQ V7.0 Fix Pack 7.0.1.7
WebSphere MQ V7.0.1 for i5/OS Fix Pack 7.0.1.7

APAR status

• Closed as program error.

Error description

• A WebSphere MQ v7 client application has several threads, with
  each thread connecting to two queue managers. When one of the
  queue managers is ended normally, there is a large delay in
  getting messages from queues on the other queue manager.
  Other symptoms seen are
  The listener threads for those connections report reason code
  2161 - MQRC_Q_MGR_QUIESCING
  WebSphere MQ log file report AMQ9208 errors
  Error on receive from host
  Listener threads report reason codes 2009
  MQRC_CONNECTION_BROKEN
  WebSphere MQ Log files report AMQ9202 errors
  Remote host not available
  While trying to reconnect, the threads report reason code
  2059 - MQRC_Q_MGR_NOT_AVAILABLE
  and 2538 MQRC_HOST_NOT_AVAILABLE
  

Local fix

• Restart application
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  Users of WebSphere MQ v7 clients where each thread connects to
  more than one queue manager.
  
  Platforms affected:
  All Distributed (iSeries, all Unix and Windows)
  ****************************************************************
  PROBLEM SUMMARY:
  The problem was a delay caused by an interdependence on a
  particular lock that is held for a long time, among three
  threads.
  
  Thread 1 obtains lock A and enters a wait state
  Thread 2 obtains lock B and waits for lock A to be released
  Thread 3 waits for lock B
  
  Threads 1 and 2 are connected to the queue manager that is
  being ended while thread 3 is dealing with the other queue
  manager and hence it is indirectly held up by the wait state of
  thread 1.
  

Problem conclusion

• The problem was fixed by modifying the code to ensure that no
  thread enters into the wait state with the lock acquired. The
  lock is released before the wait state is entered.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
                     v7.0
  Platform           Fix Pack 7.0.1.7
  --------           --------------------
  Windows            U200333
  AIX                U843721
  HP-UX (PA-RISC)    U844089
  HP-UX (Itanium)    U844094
  Solaris (SPARC)    U844090
  Solaris (x86-64)   U844096
  iSeries            tbc_p700_0_1_7
  Linux (x86)        U844091
  Linux (x86-64)     U844095
  Linux (zSeries)    U844092
  Linux (Power)      U844093
  
  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 WINDOWS V7

• Fixed component ID

  5724H7220

Applicable component levels

• R700 PSY

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