IBM Support

IT20464: Slow MQAPI calls with LONG_LOCK_WAIT, FDCs with probe IDs XC307100 XC308010

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APAR status

  • Closed as program error.

Error description

  • Queue manager generated failure data capture (FDC) records with
    error xecL_W_LONG_LOCK_WAIT in different MQAPI calls
    when processing messages from deep queues and delays observed in
    MQAPI calls.
    MQ trace shows that some threads are not getting the lock as
    expected which caused
    the LONG_LOCK_WAIT FDCs.
    
    Probe Id          :- XC307100
    Component         :- xlsRequestMutex
    Program Name      :- amqzlaa0
    Major Errorcode   :- xecL_W_LONG_LOCK_WAIT
    Probe Description :- AMQ6150: WebSphere MQ semaphore is busy.
    
    MQM Function Stack
    zlaMainThread
    zlaProcessMessage
    zlaProcessMQIRequest
    zlaMQPUT
    zsqMQPUT
    kpiMQPUT
    kqiPutIt
    kqiPutMsgSegments
    kqiTickleEarly
    apiLockExclusive
    xlsRequestMutex
    xcsFFST
    
    Probe Id          :- XC307100
    Component         :- xlsRequestMutex
    Program Name      :- amqzlaa0
    Major Errorcode   :- xecL_W_LONG_LOCK_WAIT
    Probe Description :- AMQ6150: WebSphere MQ semaphore is busy.
    
    MQM Function Stack
    zlaMainThread
    zlaProcessMessage
    zlaProcessMQIRequest
    zlaMQCMIT
    zsqMQCMIT
    kpiSyncPoint
    apiSyncPoint
    atmSyncPoint
    atxCommit
    atxPerformCommit
    aqmSyncPoint
    aocLockQHandle
    xlsRequestMutex
    xcsFFST
    
    Probe Id          :- XC308010
    Component         :- xlsReleaseMutex
    Program Name      :- amqzlaa0
    Major Errorcode   :- xecL_W_LONG_LOCK_WAIT
    Probe Description :- AMQ6150: WebSphere MQ semaphore is busy.
    
    MQM Function Stack
    zlaMainThread
    zlaProcessMessage
    zlaProcessMQIRequest
    zlaMQGET
    zsqMQGET
    kpiMQGET
    kqiWaitForMessage
    apiUnlockExclusive
    xlsReleaseMutex
    xcsFFST
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    Users consuming messages from deep queues and/or on busy systems
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    This problem occurred because IBM MQ did not give higher
    priority to MQ SRAs(threads) which were waiting for a long time.
    

Problem conclusion

  • IBM MQ code has been modified to allow the priority of the SRAs
    which are waiting for a long time to be tuned if it is deemed
    necessary by IBM support.
    
    As the need for this tuning is deemed unlikely for the majority
    of workloads, the default product behaviour is unchanged.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v8.0       8.0.0.8
    v9.0 CD    9.0.5
    v9.0 LTS   9.0.0.3
    
    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

    IT20464

  • Reported component name

    WMQ BASE MULTIP

  • Reported component ID

    5724H7251

  • Reported release

    800

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-05-04

  • Closed date

    2017-10-20

  • Last modified date

    2017-10-25

  • 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

    WMQ BASE MULTIP

  • Fixed component ID

    5724H7251

Applicable component levels

  • R800 PSY

       UP

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Document Information

Modified date:
25 October 2017