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PI92171: AN INTERMITTENT PERFORMANCE DEGRADATION IS OBSERVED WITH CICS V5.4 AND LIBERTY 17.0.0.3 COMPARED TO LIBERTY 17.0.0.1

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APAR status

  • Closed as program error.

Error description

  • An intermittent performance degradation has been observed
    running with CICS V5.4 with Liberty 17.0.0.3
    compared to CICS V5.4 with Liberty 17.0.0.1.
    Possibly  due to a change in processing incoming socket
    requests.
    
    One instance was about 4% increase in CPU cost per servlet
    request with sampling data. The sampling data showed that
    17.0.0.3 used of some functions not evident in 17.0.0.1
    related
    to TCP Select Pool.  These functions were EZBTCFSP(TCP/IP
    Select Poll) in the TCPIP region and  BPXTCSEL and EZBPFSEL
    (TCP/IP PFS Select) in OMVS region.
    
    Taking Javacore dumps of 17.0.0.1 and 17.0.0.3 running the
    same
    workload may show there is a difference in the threads.
    17.0.0.3 as an "Inbound Read Selector.1" that uses quite a
    lot
    of CPU 'CPU usage total: 85.861000000 secs'.  17.0.0.1 has a
    different thread structure.
    

Local fix

  • n/a
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  Users of IBM WebSphere Application Server   *
    *                  Liberty running inside a CICS TS V5.4       *
    *                  environment on z/OS.                        *
    ****************************************************************
    * PROBLEM DESCRIPTION: I/O performance degradation when        *
    *                      running Liberty inside a CICS TS V5.4   *
    *                      environment.                            *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    WebSphere Application Server Liberty for z/OS has a z/OS-
    specific I/O performance enhancement that is supposed to be
    enabled by default when running anywhere on the z/OS platform,
    including when running inside a CICS TS V5.4 environment.
    
    However, a specific configuration setting of the CICS TS V5.4
    environment accidentally disables this enhancement, leading to a
    performance degradation.
    

Problem conclusion

  • Updated the code so that the z/OS-specific I/O performance
    enhancement is enabled when running WebSphere Liberty inside a
    CICS TS V5.4 environment.
    
    The fix for this APAR is currently targeted for inclusion in fix
    pack 18.0.0.1.  Please refer to the Recommended Updates page for
    delivery information:
    http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
    

Temporary fix

Comments

APAR Information

  • APAR number

    PI92171

  • Reported component name

    LIBERTY PROF -

  • Reported component ID

    5655W6514

  • Reported release

    CD0

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-01-09

  • Closed date

    2018-01-31

  • Last modified date

    2018-01-31

  • 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

    LIBERTY PROF -

  • Fixed component ID

    5655W6514

Applicable component levels

  • RCD0 PSY

       UP

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Document Information

Modified date:
17 June 2020