IBM Support

IT28706: IBM MQ uses excessive memory for isolated bindings connections

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APAR status

  • Closed as program error.

Error description

  • Heap memory usage from amqzsla0 processes increase over time.
    This memory use may eventually cause available memory on the
    system to be exhausted.
    

Local fix

  • There are a couple of workarounds:
    1. Use SHARED or FAST bindings.
    2. Restart the queue manager regularly.
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Users of isolated bindings who use large messages may encounter
    this problem.	
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    The code used to communicate between applications and the queue
    manager allocates buffers large enough to hold full copies of MQ
    messages.  The design intention is that these buffers are
    resized if a large message is followed by smaller messages but
    the code to do this was incorrect.  In a system which handles a
    lot of large messages, amqzlsa0 processes may be seen to be
    using a large amount of memory.
    

Problem conclusion

  • The IBM MQ code has been corrected so that message buffers are
    correctly resized if they are larger than is needed.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v8.0       8.0.0.13
    v9.0 LTS   9.0.0.8
    v9.1 CD    9.1.3
    v9.1 LTS   9.1.0.3
    
    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

    IT28706

  • Reported component name

    IBM MQ BASE MP

  • Reported component ID

    5724H7271

  • Reported release

    910

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2019-04-06

  • Closed date

    2021-01-25

  • Last modified date

    2021-01-25

  • 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

    IBM MQ BASE MP

  • Fixed component ID

    5724H7271

Applicable component levels

[{"Line of Business":{"code":"LOB36","label":"IBM Automation"},"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"910"}]

Document Information

Modified date:
26 January 2021