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IC85614: MQ .NET XA APPLICATION IN MANAGED MODE SHOWS MEMORY LEAKS AND SPAWNS NUMEROUS AMQZLAA0 PROCESSES

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APAR status

  • Closed as program error.

Error description

  • WebSphere MQ .NET extended transaction (XA) application
    generates numerous amqzlaa0 processes and shows memory leaks.
    Application is running in MANAGED client mode.
    
    While application is running:
    - Memory usage keeps increasing and it does not stabilize.
    - CPU usage is between 90% and 100%.
    - Hundreds of amqzlaa0 processes are created.
    - Message throughput is very slow.
    
    Eventually the application receives MQRC_CONNECTION_BROKEN
    and MQRC_CONNECTION_ERROR errors. Communication are reported
    in the queue manager error logs. FDC is generated for the
    application.
    
    AMQ9208: Error on receive from host (xxxxxxxx)
    An error occurred receiving data from xxxxxxxx over TCP/IP
    The return code from the TCP/IP call was 10054 (X'2547')
    
    FDC shows the following:
    Probe Id :- DN<99001
    Component :- NmqiXAResourceManager.MQRMIXACommit(Bool
    Major Errorcode :- rrcE_COMMUNICATIONS_ERROR
    Probe Description :- AMQ9213: A communications error for recv
    occurred
    Comment1 :- xa_commit call has failed with return code = -4
    
    MQM Function Stack
    Unknown Function - 073 252
    Unknown Function - 073 275
    xcsFFST
    

Local fix

  • Local Fix&#65496;
    none
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Users using WebSphere MQ .NET managed XA client application.
    This problem is applicable to WebSphere MQ v7.1 and v7.5.
    
    Platforms affected:
    Windows
    
    ****************************************************************
    PROBLEM SUMMARY:
    The below issues were seen when MQ .NET managed transactional
    clients are run.
    1) The xa_commit call fails with invalid transaction error -4
    and a FDC with the below function stack is created
    
    MQM Function Stack
    MQDTCCallbackObserver.Commit(Enlistment)
    NmqiXAResourceManager.MQRMIXACommit(Boolean)
    ManagedCommonServices.FFST
    (String,string,string,uint,uint,MQULONG,MQULONG,ushort)
    
    | Comment1          :- xa_commit call has failed with return
    code = -4        |
    
    In a  2-phase commit, if xa_prepare completes with XA_RDONLY
    then a further commit need not be issued. This return code
    implies that the transaction is complete.
    
    2) The number of running agent processes keeps increasing
    constantly. The queue manager trace shows that most of the
    agent processes were idle. The agent threads created for
    servicing the MQI request of a connection are ended or reused
    after the application disconnects. However, this thread is
    neither reused nor freed if it is part of a active transaction.
    This was happening since the MQ .NET layer did not correctly
    end the transaction even though a xa_close was issued. Hence,
    when one agent process reaches its thread limit a new agent
    process gets created.
    
    3) Memory leak was seen since the TSH buffer was not released
    during disconnect.
    

Problem conclusion

  • The WebSphere MQ .NET code has been modified to fix the issues
    seen when transactional clients are run.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following:
    
                       v7.1
    Platform           Fix Pack 7.1.0.3
    --------           --------------------
    Windows            7.1.0.3
    
    Version            v7.5
    --------           --------------------
    Fix available in:  7.5.0.3
    
    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

    IC85614

  • Reported component name

    WMQ WINDOWS V7

  • Reported component ID

    5724H7220

  • Reported release

    710

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2012-07-30

  • Closed date

    2012-10-15

  • Last modified date

    2013-06-17

  • 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 WINDOWS V7

  • Fixed component ID

    5724H7220

Applicable component levels

  • R710 PSY

       UP

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Document Information

Modified date:
20 September 2021