PM42033: MESSAGES ON MQ SERVER NOT CONSUMED DUE TO DEADLOCK

7.0.0.21: WebSphere Application Server V7.0 Fix Pack 21
7.0.0.23: WebSphere Application Server V7.0 Fix Pack 23
7.0.0.25: WebSphere Application Server V7.0 Fix Pack 25
7.0.0.27: WebSphere Application Server V7.0 Fix Pack 27
7.0.0.29: WebSphere Application Server V7.0 Fix Pack 29
7.0.0.31: WebSphere Application Server V7.0 Fix Pack 31
7.0.0.27: Java SDK 1.6 SR13 FP2 Cumulative Fix for WebSphere Application Server
7.0.0.33: WebSphere Application Server V7.0 Fix Pack 33
7.0.0.35: WebSphere Application Server V7.0 Fix Pack 35
7.0.0.37: WebSphere Application Server V7.0 Fix Pack 37
7.0.0.39: WebSphere Application Server V7.0 Fix Pack 39
7.0.0.41: WebSphere Application Server V7.0 Fix Pack 41
7.0.0.43: WebSphere Application Server V7.0 Fix Pack 43
7.0.0.45: WebSphere Application Server V7.0 Fix Pack 45
7.0.0.21: Java SDK 1.6 SR9 FP2 Cumulative Fix for WebSphere
7.0.0.23: Java SDK 1.6 SR10 FP1 Cumulative Fix for WebSphere
7.0.0.25: Java SDK 1.6 SR11 Cumulative Fix for WebSphere Application Server
7.0.0.27: Java SDK 1.6 SR12 Cumulative Fix for WebSphere Application Server
7.0.0.29: Java SDK 1.6 SR13 FP2 Cumulative Fix for WebSphere Application Server
7.0.0.45: Java SDK 1.6 SR16 FP60 Cumulative Fix for WebSphere Application Server
7.0.0.31: Java SDK 1.6 SR15 Cumulative Fix for WebSphere Application Server
7.0.0.35: Java SDK 1.6 SR16 FP1 Cumulative Fix for WebSphere Application Server
7.0.0.37: Java SDK 1.6 SR16 FP3 Cumulative Fix for WebSphere Application Server
7.0.0.39: Java SDK 1.6 SR16 FP7 Cumulative Fix for WebSphere Application Server
7.0.0.41: Java SDK 1.6 SR16 FP20 Cumulative Fix for WebSphere Application Server
7.0.0.43: Java SDK 1.6 SR16 FP41 Cumulative Fix for WebSphere Application Server

APAR status

• Closed as program error.

Error description

• Using the MQ Server feature of the Service Integration Bus,
  messages are not delivered to a consumer from a destination
  on the MQ Server queue manager.  A javacore from the JVM
  hosting the MQ Server shows the following deadlock:
  
  Thread 1:
  
  com/ibm/ws/sib/processor/impl/RMQAsynchThread.resume(RMQAsynchTh
  read.java:182)
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQConsumerKey.resumeRMQAsyncThrea
  d(RMQConsumerKey.java:280)--> waiting to lock on RMQAsynchThread
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQLocalConsumerPoint.resumeConsum
  er(RMQLocalConsumerPoint.java:1968) -->
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQLocalConsumerPoint.removeActive
  Messages(RMQLocalConsumerPoint.java:1596) --> holding a lock
  on RMQLocalConsumerPoint
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQLocalConsumerPoint.afterComplet
  ion(RMQLocalConsumerPoint.java:2057)
  ...
  
  Thread 2:
  com/ibm/ws/sib/processor/impl/RMQLocalConsumerPoint.addAsynchMes
  sage(RMQLocalConsumerPoint.java:1756) --> waiting to lock
  RMQLocalConsumerPoint
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQAsynchThread$AsynchRunnable.run
  AsynchConsumer(RMQAsynchThread.java:575(Compiled Code))
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQAsynchThread$AsynchRunnable.acc
  ess$300(RMQAsynchThread.java:197)
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQAsynchThread.start(RMQAsynchThr
  ead.java:121)---> holding a lock on RMQAsynchThread
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQConsumerKey.startRMQAsyncThread
  (RMQConsumerKey.java:229)
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQLocalConsumerPoint.internalStar
  t(RMQLocalConsumerPoint.java:1858)
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/RMQLocalConsumerPoint.start(RMQLoc
  alConsumerPoint.java:1245)
  4XESTACKTRACE at
  com/ibm/ws/sib/processor/impl/ConsumerSessionImpl.start(Consumer
  SessionImpl.java:855)
  4XESTACKTRACE at
  ...
  

Local fix

• All messages are processed after restart of the Servant region.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:  Users of the default messaging provider     *
  *                  for                                         *
  *                  IBM WebSphere Application Server using the  *
  *                  MQ Server functionality                     *
  ****************************************************************
  * PROBLEM DESCRIPTION: A deadlock prevents messages being      *
  *                      consumed from an MQ Server bus memner   *
  *                      destination                             *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The deadlock occurs when the thread responsible for message
  retrieval runs inline with the the start of the consumer.
  This causes the lock hierachy to be broken and an ABBA
  deadlock ensues.
  

Problem conclusion

• This APAR resolves the deadlock by ensuring that the lock
  hierarchy is observed when the thread to retrieve messages is
  run inline with the thread starting the consumer.
  
  The fix for this APAR is currently targeted for inclusion in
  fix pack 7.0.0.21.  Please refer to the Recommended Updates
  page for delivery information:
  
  http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
  

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

  WAS SIB & SIBWS

• Fixed component ID

  620800101

Applicable component levels

• R800 PSY

     UP