PM82672: IPIC PERFORMANCE IMPROVEMENT WITH LOCK WAIT REDUCTION

A fix is available

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • You are running a stress workload to cross instance applications
    with RTIMOUT and MONITOR timeouts set to purge transactions that
    take excessive time to complete.  When one region is slowed, the
    processing is affected on the other regions, as multiple tasks
    are delayed and eventually purged.
    .
    Investigation of dumps reveal that much time is spent by tasks
    waiting for the exclusive lock for an INQUIRE call for DFHSOTB.
    The information sought from the INQUIRE is the port number of
    the TCPIPSERVICE.  This information is static, and could be
    obtained and saved during CAPEX processing, avoiding the lock
    entirely at this juncture.
    KIXREVEAA
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED: All CICS users.                              *
    ****************************************************************
    * PROBLEM DESCRIPTION: CICS region slowdown after a large      *
    *                      number of IPIC DPL requests are         *
    *                      received.                               *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    A large number of IPIC DPL requests are received in CICS.
    Mirror tasks are attached in the remote region to handle them.
    When each mirror task starts, DFHISXM runs for init and bind.
    During bind, a monitoring performance record is captured.
    This record requires the TCPIPSERVICE name and port number.
    The port number is not held by IS domain so a DFHSOTB
    INQUIRE_TCPIPSERVICE call is made.
    DFHSOTB acquires the TCPIPSERVICE lock exclusively, and then
    gathers the information required to satisfy the inquire (by
    calling DFHSOTD).  This does not check which fields were
    requested so does a lot of processing, including switching
    to the SO TCB as part of inquire_connection.
    While on the SO TCB the next mirror task can start on QR.
    It reaches DFHSOTB and then suspends waiting for the lock.
    In a busy system many mirror tasks can end up waiting.
    The first mirror task returns to QR and releases the lock.
    The other mirror tasks all resume and retry the lock acquire.
    This causes excessive processing as tasks suspend and resume.
    Due to the nondeterministic nature of lock acquire, some tasks
    may time out after multiple attempts to acquire the lock.
    

Problem conclusion

  • Copybook DFHISDCC is changed to add field iscb_tcpips_port to
    the ISCB (IPCONN) control block.
    Module DFHISXM is changed to store the TCPIPSERVICE port number
    in iscb_tcpips_port for the applicable ISCB.
    Program DFHISCOP is changed to clear iscb_tcpips_port in the
    ISCB when the associated IPCONN is released.
    

Temporary fix

  • FIX AVAILABLE BY PTF ONLY
    

Comments

APAR Information

  • APAR number

    PM82672

  • Reported component name

    CICS TS Z/OS V4

  • Reported component ID

    5655S9700

  • Reported release

    700

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2013-02-13

  • Closed date

    2013-05-23

  • Last modified date

    2013-07-02

  • APAR is sysrouted FROM one or more of the following:

  • APAR is sysrouted TO one or more of the following:

    PM88910

Modules/Macros

  •    DFHCIS4  DFHISAL  DFHISCO  DFHISCOP DFHISCU
    DFHISDM  DFHISDUF DFHISEM  DFHISEMP DFHISFS  DFHISIC  DFHISIF
    DFHISIS  DFHISJU  DFHISLQ  DFHISLQP DFHISRE  DFHISRR  DFHISRRP
    DFHISRS  DFHISRSP DFHISSR  DFHISST  DFHISTRI DFHISUE  DFHISXF
    DFHISXM  DFHISXS  DFHISZA  DFHMIRS
    

Fix information

  • Fixed component name

    CICS TS Z/OS V4

  • Fixed component ID

    5655S9700

Applicable component levels

  • R700 PSY UK94609

       UP13/06/04 P F306

Fix is available

  • Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.



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Document information


More support for:

CICS Transaction Server

Software version:

4.2

Reference #:

PM82672

Modified date:

2013-07-02

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