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IT30124: Queue manager unavailable under high load. Reports AMQ6150: WebSphere MQ semaphore is busy

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APAR status

  • Closed as program error.

Error description

  • The MQ application can not connect, receiving the "MQ is
    unavailable" error.  On the queue manager, this semaphore error
    appears every 15 minutes:
    
    AMQ6150: WebSphere MQ semaphore is busy
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Users connecting several thousand applications to a queue
    manager may encounter FFSTs, this is more likely to occur on the
    Windows platform due to the shared memory server.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    When a large number of connections are made to a queue manager,
    the primary shared memory sets that are used to track the
    connections may need to be extended. When this extension
    occurred, a new connection held a queue-manager-wide lock whilst
    the additional shared memory segments were attached. On the
    Windows platform the attach of the additional shared memory
    involved interprocess communication with the shared subpool
    server, this caused contention on the lock and generated FFSTs.
    

Problem conclusion

  • The logic to attach extended shared memory sets was reworked to
    avoid lock contention.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v9.0 LTS   9.0.0.9
    v9.1 CD    9.1.5
    v9.1 LTS   9.1.0.4
    
    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

    IT30124

  • 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

    2019-08-29

  • Closed date

    2019-10-25

  • Last modified date

    2019-10-25

  • 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 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:
25 October 2019