IV00757: WMQ V7 JMS APPLICATION HANGS DUE TO A THREAD DEADLOCK WHEN CLOSING MESSAGECONSUMER OR SESSION

WebSphere MQ V7.0 Fix Pack 7.0.1.7
WebSphere MQ V7.0.1 for i5/OS Fix Pack 7.0.1.7
WebSphere MQ v7.0.1.7 Hypervisor for AIX
Fix Pack 7.1.0.2 for WebSphere MQ V7.1

APAR status

• Closed as program error.

Error description

• WMQ V7 JMS application hangs, and there are no FFSTs or
  exceptions issued. Javacore will show a deadlock between two
  threads:
  consumer closing thread:
  Owns Monitor Lock on java/lang/Object@0x00C5A438/0x00C5A444
  at java/lang/Object.wait(Native Method)
  at java/lang/Object.wait(Object.java:167)
  at
  com/ibm/mq/jmqi/remote/internal/RemoteHconn.
  waitOnDispatchEvent(RemoteHconn.java:677)
  at
  com/ibm/mq/jmqi/remote/internal/RemoteHconn.
  dispatchThreadExchange(RemoteHconn.java:721)
  at
  com/ibm/mq/jmqi/remote/internal/RemoteFAP.
  MQCTL(RemoteFAP.java:2372)
  at
  com/ibm/msg/client/wmq/internal/WMQConsumerOwnerShadow.
  suspendAsyncService(WMQConsumerOwnerShadow.java:698)
  at
  com/ibm/msg/client/wmq/internal/WMQSession.
  suspendAsyncService(WMQSession.java:1605)
  at
  com/ibm/msg/client/wmq/internal/WMQConsumerShadow.
  close(WMQConsumerShadow.java:285)
  at
  com/ibm/msg/client/wmq/internal/WMQMessageConsumer.
  close(WMQMessageConsumer.java:379)
  at
  com/ibm/msg/client/jms/internal/JmsMessageConsumerImpl.
  close(JmsMessageConsumerImpl.java:257)
  at
  com/ibm/msg/client/jms/internal/JmsMessageConsumerImpl.
  close(JmsMessageConsumerImpl.java:183)
  at
  com/ibm/mq/jms/MQQueueReceiver.close(MQQueueReceiver.java:80)
  
  and the MessageConsumerThread:
  Waiting for Monitor Lock on
  java/lang/Object@0x00C5A438/0x00C5A444
  at
  com/ibm/msg/client/jms/internal/JmsSessionImpl.
  rollback(JmsSessionImpl.java:1640)
  at com/ibm/mq/jms/MQSession.rollback(MQSession.java:842)
  at test/testcases/CloseTest$1.onMessage(CloseTest.java:83)
  at
  com/ibm/mq/jms/MQMessageConsumer$FacadeMessageListener.
  onMessage(MQMessageConsumer.java:399)
  at
  com/ibm/msg/client/jms/internal/
  JmsMessageConsumerImpl$JmsProviderMessageListener.
  onMessage(JmsMessageConsumerImpl.java:940)
  at
  com/ibm/msg/client/wmq/internal/WMQAsyncConsumerShadow.
  honourNoLocal(WMQAsyncConsumerShadow.java:565)
  at
  com/ibm/msg/client/wmq/internal/WMQAsyncConsumerShadow.
  consumer(WMQAsyncConsumerShadow.java:399)
  at
  com/ibm/mq/jmqi/remote/internal/RemoteAsyncConsume.
  driveConsumer(RemoteAsyncConsume.java:1526)
  at
  com/ibm/mq/jmqi/remote/internal/RemoteAsyncConsume.
  checkTxnMsg(RemoteAsyncConsume.java:1198)
  at
  com/ibm/mq/jmqi/remote/internal/RemoteDispatchThread.
  run(RemoteDispatchThread.java:300)
  at
  com/ibm/msg/client/commonservices/workqueue/WorkQueueItem.
  runTask(WorkQueueItem.java:209)
  at
  com/ibm/msg/client/commonservices/workqueue/
  SimpleWorkQueueItem.runItem(SimpleWorkQueueItem.java:100)
  at
  com/ibm/msg/client/commonservices/workqueue/WorkQueueItem.
  run(WorkQueueItem.java:224)
  at
  com/ibm/msg/client/commonservices/workqueue/WorkQueueManager.
  runWorkQueueItem(WorkQueueManager.java:298)
  at
  com/ibm/msg/client/commonservices/j2se/workqueue/
  WorkQueueManagerImplementation$ThreadPoolWorker.
  run(WorkQueueManagerImplementation.java:1220)
  

Local fix

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of the WebSphere MQ V7 classes for JMS
  that make JMS method calls from within a MessageListener, and
  that attempt to close the owning MessageConsumer while the
  MessageListener is processing a message.
  
  Platforms affected:
  All Distributed (iSeries, all Unix and Windows) +Java +Java zOS
  ****************************************************************
  PROBLEM SUMMARY:
  The problem can arise if a call is made within a MessageListener
  that requires communication with the queue manager (for example
  calling Session.rollback()), but at the same time, another
  thread attempts to close the owning MessageConsumer (either
  directly or by closing the owning Session or Connection).
  
  A deadlock can occur as the close() and rollback() calls are
  serialized, if the close() call begins before the rollback() the
  rollback() is blocked until the close() completes. However, as
  per the JMS specification, the close() call will block until all
  message processing (including that in the MessageListener) has
  returned. However, the MessageListener cannot return until the
  rollback() has completed, hence a deadlock results.
  

Problem conclusion

• New locking was implemented to separate out synchronous API
  calls from asynchronous serialization. These changes allow the
  MessageListener to continue making JMS API calls while the
  closing thread is blocked, and then to return to the queue
  manager, allowing the closing thread to complete.
  
  ---------------------------------------------------------------
  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
  zOS                7.0.1.7
  
  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

• R700 PSY

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