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IV16597: WEBSPHERE MQ V7.0JMS CLIENT HANGS IN A FINALIZER THREAD CAUSING AN OUT OF MEMORY CONDITION.

Fixes are available

WebSphere MQ V7.0 Fix Pack 7.0.1.9
Fix Pack 7.1.0.2 for WebSphere MQ V7.1

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APAR status

  • Closed as program error.

Error description

  • An OutOfMemory (OOM) condition is experienced when the heap
fills up with MessageContext objects using WebSphere MQ classes
for JMS.  A javacore shows that the finalizer thread stuck
within the following stack:

"Finalizer thread" J9VMThread:0x0000000030CCF800, j9thread_t:
0x000000011959EE40, java/lang/Thread:0x0000000040DD60E0,
state:CW, prio=5
(native thread ID:0x30A01FB, native priority:0x5, native
policy:UNKNOWN)
Java callstack:
at java/lang/Object.wait(Native Method)
at java/lang/Object.wait(Object.java:196(Compiled Code))
at
com/ibm/mq/jmqi/remote/internal/system/RemoteConnection.sendTSH
(RemoteConnection.java:2221(Compiled code))
at
com/ibm/mq/jmqi/remote/internal/RemoteHconn.sendTSH(RemoteHconn
.java:1111(Compiled Code))
at
com/ibm/mq/jmqi/remote/internal/RemoteFAP.MQDISC(RemoteFAP.java
:2552(Compiled Code))
at
com/ibm/msg/client/wmq/internal/WMQConnection.close(WMQConnecti
onjava:732(Compiled Code))
at
com/ibm/msg/client/jms/internal/JmsConnectionImpl.close(JmsConn
ectionImpl.java:352(Compiled Code)
at
com/ibm/msg/client/jms/internal/JmsConnectionImpl.finalize(JmsC
onnectionImpl.java:224(Compiled Code))
at
java/lang/J9VMInternals.runFinalize(J9VMInternals.java:412(Comp
iledCode))

Local fix

  • Local Fix￘
Restart JVMs to clear the heap.

Problem summary

  • ****************************************************************
USERS AFFECTED:
This issue affects users of the WebSphere MQ classes for JMS,
WebSphere MQ classes for Java or WebSphere MQ Resource Adapter,
who are using a 'REMOTE' (TCP) connection to communicate with
a queue manager.

Platforms affected:
All Distributed (iSeries, all Unix and Windows) +Java +Java zOS
****************************************************************
PROBLEM SUMMARY:
The problem was caused by code that serialized access to certain
communication functions.  Conditions may arise where a thread
will lock access but not release, which means that any
subsequent thread to access the communications object will
block indefinitely.

This can cause a hang condition, or if the thread that is
blocked is the finalizer thread, this can prevent the JVM
garbage collector from running, which will lead to an
OutOfMemory condition occurring.

Problem conclusion

  • The code has been changed to ensure a thread that takes a lock
will also release it.

As part of the code change, further diagnostics were also added
to the code base.  If a similar condition occurs again within
the communication classes, FDC files will be generated which
have a probeID of:

.          JO215002
.          JO215003


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

                   v7.0
Platform           Fix Pack 7.0.1.9
--------           --------------------
Windows            U200337
AIX                U849391
HP-UX (PA-RISC)    U849723
HP-UX (Itanium)    U849728
Solaris (SPARC)    U849724
Solaris (x86-64)   U849730
iSeries            7.0.1.9
Linux (x86)        U849725
Linux (x86-64)     U849729
Linux (zSeries)    U849726
Linux (Power)      U849727
zOS                7.0.1.9

                   v7.1
Platform           Fix Pack 7.1.0.2
--------           --------------------
Windows            7.1.0.2
AIX                7.1.0.2
HP-UX (Itanium)    7.1.0.2
Solaris (SPARC)    7.1.0.2
Solaris (x86-64)   7.1.0.2
iSeries            7.1.0.2
Linux (x86)        7.1.0.2
Linux (x86-64)     7.1.0.2
Linux (zSeries)    7.1.0.2
Linux (Power)      7.1.0.2
zOS                7.1.0.2

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
    IV16597
    • 

  • Reported component name
    WMQ AIX V7
    • 

  • Reported component ID
    5724H7221
    • 

  • Reported release
    701
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt
    • 

  • Submitted date
    2012-03-02
    • 

  • Closed date
    2012-04-29
    • 

  • Last modified date
    2012-04-29
    • 





    

  • 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


    

  • R701  PSY
       UP
    • 








      
              
                            

              

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Document Information


            

            


                        

            Modified date:
            

            31 March 2023
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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