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IV57472: WMQ 7.1 AMQ9504 PROTOCOL ERROR RECEIVED AT THE QMGR AND AMQ9213 AT THE CLIENT WHEN A JMS SESSION IS SHARED BY MULTIPLE THREADS

Fixes are available

Fix Pack 7.1.0.6 for WebSphere MQ V7.1
8.5.5.6: WebSphere Application Server V8.5.5 Fix Pack 6
8.5.5.7: WebSphere Application Server V8.5.5 Fix Pack 7
8.5.5.8: WebSphere Application Server V8.5.5 Fix Pack 8
8.5.5.9: WebSphere Application Server V8.5.5 Fix Pack 9
8.5.5.10: WebSphere Application Server V8.5.5 Fix Pack 10
8.5.5.11: WebSphere Application Server V8.5.5 Fix Pack 11
8.5.5.12: WebSphere Application Server V8.5.5 Fix Pack 12
8.5.5.13: WebSphere Application Server V8.5.5 Fix Pack 13
8.5.5.14: WebSphere Application Server V8.5.5 Fix Pack 14
8.5.5.15: WebSphere Application Server V8.5.5 Fix Pack 15
8.5.5.17: WebSphere Application Server V8.5.5 Fix Pack 17
8.5.5.20: WebSphere Application Server V8.5.5.20
8.5.5.18: WebSphere Application Server V8.5.5 Fix Pack 18
8.5.5.19: WebSphere Application Server V8.5.5 Fix Pack 19
8.5.5.16: WebSphere Application Server V8.5.5 Fix Pack 16
8.5.5.21: WebSphere Application Server V8.5.5.21

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APAR status

  • Closed as program error.

Error description

  • The queue manager reports an AMQ9504 protocol error when a JMS
QueueSession
is shared between multiple threads.
From one thread an MQDISC call arrives at the queue manager
and ends the conversation while at approximately the same time
that JMS QueueSession is used to send an internal spiNotify
call request on another QueueReceiver from a different thread.
AMQ9213 is returned by the JMS Client.

Local fix

  • 



Problem summary


    

  • ****************************************************************
USERS AFFECTED:
This issue affects users of:

- The WebSphere MQ V7.1 classes for JMS.
- The WebSphere MQ V7.1 resource adapter.
- The WebSphere MQ V7.5 classes for JMS.
- The WebSphere MQ V7.5 resource adapter.
- The WebSphere Application Server V8.5 WebSphere MQ messaging
provider.

who have multi-threaded applications that connect to a WebSphere
MQ queue manager using WebSphere MQ messaging provider normal
mode using the CLIENT transport and:

- Create a JMS Session, and a JMS MessageConsumer from the JMS
Session, on one thread.
- Close the JMS Session from a different thread to the one that
is using it.


Platforms affected:
MultiPlatform

****************************************************************
PROBLEM DESCRIPTION:
When an application creates a JMS session, a connection handle
(hconn) is assigned to the JMS session and is used whenever the
JMS session communicates with the queue manager. If a WebSphere
MQ API call needs to be sent to the queue manager, the WebSphere
MQ classes for JMS obtain a Call Lock on the connection handle,
issue the call and then release the Call Lock. The use of the
Call Lock prevents multiple WebSphere MQ API calls being made on
the same connection handle at the same time.

This means that when a JMS session is closed, the WebSphere MQ
classes for JMS will:

- Get the Call Lock for the connection handle associated with
the JMS Session.
- Flow an MQDISC call to the queue manager using the connection
handle.
- When the MQDISC call completes, release the Call Lock.

While the MQDISC processing is taking place, no other WebSphere
MQ API calls can be made on the connection handle.

When a JMS MessageConsumer is created by an application which is
connecting to a queue manager using WebSphere MQ messaging
provider normal mode, the WebSphere MQ classes for JMS will:

- Register a callback on the queue that the MessageConsumer has
been asked to monitor, using the WebSphere MQ API MQCB.
- Flow an internal notify WebSphere MQ call to the queue
manager, telling it to start sending it messages.

When the JMS MessageConsimer is closed, the WebSphere MQ classes
for JMS will flow another notify call to the queue manager,
telling it to stop sending messages. In order to flow the notify
calls when either a MessageConsumer is created or closed, the
WebSphere MQ classes for JMS obtain an internal Notify Lock on
the connection handle for the JMS session that the
MessageConsumer was created from. The Notify Lock is released
when the notify call completes.


If one thread within an application was trying to close a JMS
session at the same time as another thread was trying to close a
MessageConsumer created from that JMS session, the following
behaviour occurred:

- Thread 1 called Session.close().
- Thread 2 called MessageConsumer.close().
- Thread 1 got the Call Lock for the connection handle
associated with the JMS Session.
- Thread 2 got the Notify Lock for the connection handle
associated with the JMS Session.
- Thread 1 flowed an MQDISC down to the queue manager.
- The queue manger processed the MQDISC call, disconnected the
connection handle and sent back a reply to the WebSphere MQ
classes for JMS.
- Thread 1 processed the MQDISC reply.
- Thread 2 flowed an internal notify call to the queue manager.
- Thread 1 released the Call Lock.
- The queue manager processed the notify call, and reported an
AMQ9504 error as the connection handle that the notify call was
made on had just been disconnected.

    



Problem conclusion


    

  • The WebSphere MQ classes for JMS have been updated to ensure
that both the Call Lock and the Notify Lock are held when an
MQDISC call needs to be made. This means that:

- If a notify call is being made on a connection handle when
another thread tries to flow MQDISC call to the queue manager to
close a JMS session, the MQDISC call needs to wait for the
notify to complete before it can be flowed to the queue manager.
- If an MQDISC call is in progress when another thread tries to
call notify, the notify flow will not be sent to the queue
manager.

---------------------------------------------------------------
The fix is targeted for delivery in the following PTFs:

Version    Maintenance Level
v7.1       7.1.0.6
v7.5       7.5.0.5

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 number
    IV57472
    • 

  • Reported component name
    WMQ LIN X86 V7
    • 

  • Reported component ID
    5724H7224
    • 

  • Reported release
    710
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt
    • 

  • Submitted date
    2014-03-27
    • 

  • Closed date
    2014-05-13
    • 

  • Last modified date
    2014-05-13
    • 





    

  • 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 LIN X86 V7
    • 

  • Fixed component ID
    5724H7224
    • 



Applicable component levels


    

  • R710  PSY
       UP
    • 








      
              
                            

              

              [{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSFKSJ","label":"WebSphere MQ"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"7.1","Line of Business":{"code":"LOB45","label":"Automation"}}]
              

                          

          
 
        

      

    

      

        

          

            
Document Information


            

            


                        

            Modified date:
            

            28 April 2022
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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