IC69703: WMQ EXPLORER HANGS WITH PROBE ID JU:40010, WHILE TRACING IS ENABLED AND THE WMQFTE TRANSFER LOG IS LOST.

WebSphere MQ V7.0.1 for i5/OS Fix Pack 7.0.1.3
WebSphere MQ V7.0 Fix Pack 7.0.1.3

APAR status

• Closed as program error.

Error description

• The WebSphere MQ Explorer is hanging and loosing the WebSphere
  MQ File Transfer Edition transfer log. The FDC files generated
  at the time of the hang indicate "Failed to create content
  page." The probe id for MQ is JU:40010.
  
  The problem is only seen when WebSphere MQ tracing is enabled.
  Even then, the hang is mainly experienced when wrapping
  trace is used.
  

Local fix

• Avoid running a wrapping WebSphere MQ trace.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  All users of WebSphere MQ on the Windows platform who enable
  wrapping trace.
  
  Platforms affected:
  Windows
  
  ****************************************************************
  PROBLEM SUMMARY:
  The problem occurs due to a deadlock between two threads as
  follows:
  
  1) Thread A has just entered DllMain in the transaction manager
  component on Windows (amqmtmgr) and is attempting to write a
  trace point. As a result, it currently holds the loader lock
  (because it is in DllMain) and is blocked waiting on the trace
  lock to become available.
  
  2) Meanwhile, thread B has already entered a trace point and
  grabs the trace lock. At this point, it determines that it is
  now time for the trace files to wrap so it attempts to write a
  new trace file header. The trace header includes some OS
  specific data retrieved from function xcsGetHostInfo. This
  includes attempts to load system library kernel32.dll and so, it
  attempts to acquire the loader lock. However, thread A already
  has the loader lock hence the deadlock.
  
  Even with trace, the problem should not occur very often as it
  relies on a timing window where the trace files are wrapped at
  the same time as another thread is entering DllMain for one of
  the MQ dlls.
  

Problem conclusion

• Code change ensures that the deadlock does not occur between
  the threads thus preventing the hang in the application process.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
                     v7.0
  Platform           Fix Pack 7.0.1.3
  --------           --------------------
  Windows            U200320
  
  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:

  IC68773

• 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

• R701 PSY

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