IBM Support

IT26707: amqsevt sample uses high CPU when running as an IBM MQ Service

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APAR status

  • Closed as program error.

Error description

  • When starting the sample amqsevt as an IBM MQ Service then
    commands such as top or ps show the amqsevt process using
    almost 100% of a CPU core.
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Users who wish to run the amqsevt sample as an IBM MQ Service on
    a non-Windows Operating System will be affected
    by this problem.
    
    
    Platforms affected:
    Solaris x86-64, Solaris SPARC, Linux on zSeries, Linux on
    x86-64, Linux on x86, Linux on S390, Linux on Power, IBM
    iSeries, HP-UX OpenVMS, HP-UX PA-RISC, HP-UX Itanium, AIX
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    When IBM MQ starts a service, it assigns the stdin file
    descriptor to /dev/null.  Some interactive applications such as
    amqsevt may not function correctly in this environment.  In the
    case of amqsevt, the select() call in the input loop would
    constantly be woken up by bytes being sent to it from /dev/null
    and so the sample would enter a tight loop.
    

Problem conclusion

  • The amqsevt sample has been modified to detect whether a
    terminal is being used for stdin.  If it is not then the sample
    sleeps for 5 seconds in a loop rather than waiting for input.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v9.0 LTS   9.0.0.6
    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

    IT26707

  • Reported component name

    IBM MQ BASE M/P

  • Reported component ID

    5724H7261

  • Reported release

    900

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-10-23

  • Closed date

    2019-01-10

  • Last modified date

    2019-01-10

  • 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:
10 January 2019