IBM Support

IT27072: Memory leak in IBM MQ on Linux after a queue is emptied

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APAR status

  • Closed as program error.

Error description

  • IBM MQ keeps details of queued messages in shared memory
    and in some cases this memory is not freed completely when it
    should
    be.  For example, issuing "CLEAR QLOCAL" against a queue which
    was previously
    open but has since been closed.
    

Local fix

  • This problem only affects queues containing more than 8192
    messages and so avoiding deep queues is one workaround.
    

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Users on Linux with deep queues are more likely to be affected
    by this problem.
    
    
    Platforms affected:
    Linux on Power, Linux on S390, Linux on x86, Linux on x86-64,
    Linux on zSeries
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    Over a period of time the amount of shared memory that is being
    used by IBM MQ may be seen to be growing in an uncontrolled
    manner.  This was caused by a gcc compiler upgrade which
    introduced an optimisation that affected the way that IBM MQ
    behaves when removing internal queue meta-data.
    

Problem conclusion

  • The affected IBM MQ code has been modified so that aggressive
    loop optimisation does not modify intended behaviour.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v9.0 LTS   9.0.0.7
    v9.1 CD    9.1.2
    v9.1 LTS   9.1.0.2
    
    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

    IT27072

  • Reported component name

    IBM MQ BASE M/P

  • Reported component ID

    5724H7261

  • Reported release

    900

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-11-22

  • Closed date

    2019-02-28

  • Last modified date

    2019-02-28

  • 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 M/P

  • Fixed component ID

    5724H7261

Applicable component levels

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"9.0","Edition":"","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]

Document Information

Modified date:
28 February 2019