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PI75474: SOME REQUEST RECEIVE 404 OR 503 RESPONSES WHEN INTRODUCING A NEW ODR ROUTING OR GSC RULE.

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APAR status

  • Closed as program error.

Error description

  • When a new ODR routing rule or ODR routing rule for a GSC is
    added, a few requests flowing at that time may receive 404
    or 503 responses if they match the rule.  Prior requests and
    subsequent requests will be processed as expected.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  All uses of IBM WebSphere Application       *
    *                  Server On Demand Router rules               *
    ****************************************************************
    * PROBLEM DESCRIPTION: Some requests may receive 404 or 503    *
    *                      responses for a short time when         *
    *                      introducing a new Routing policy HTTP   *
    *                      rules or new Generic Service Cluster    *
    *                      (GSC) routing policies on the On Demand *
    *                      Router (ODR)                            *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    When a new ODR routing rule such as Routing policy HTTP rules or
    GSC routing policies, it is possible that a few requests that
    arrive at about the same time as the rule creation may match the
    rule condition and receive a 404 or 503 response.  This is
    because the new routing policy rule is introduced into the
    system before it is completely initialized and therefore
    matching requests may be incorrectly processed.  It is a very
    small timing window when requests are arriving at the same time
    that the rule is being added. This issue may not affect any
    requests but if it does it typically only affects a small number
    of requests because the window is so small.  Normal processing
    will return as soon as the rule initialization is complete which
    typically takes tens of milliseconds depending on the traffic
    load on the ODR.
    

Problem conclusion

  • The ODR logic has been updated to remove this timing window by
    ensuring that the rule initialization is complete before it is
    made available to match incoming requests.
    
    The fix for this APAR is currently targeted for inclusion in fix
    pack 8.5.5.12.  Please refer to the Recommended Updates page for
    delivery information:
    http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980
    

Temporary fix

  • Avoid installing new routing rules such as Http Routing policies
    or GSC routing policies into the On Demand Router during times
    when requests are likely to be arriving that would match the
    rule.  The problem is self correcting within milliseconds as the
    rule processing continues and only a very small window is open
    when requests could be processed incorrectly.
    

Comments

APAR Information

  • APAR number

    PI75474

  • Reported component name

    WEBS APP SERV N

  • Reported component ID

    5724H8800

  • Reported release

    850

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-01-25

  • Closed date

    2017-01-26

  • Last modified date

    2017-02-15

  • 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

    WEBS APP SERV N

  • Fixed component ID

    5724H8800

Applicable component levels

  • R850 PSY

       UP

[{"Line of Business":{"code":"LOB10","label":"Data and AI"},"Business Unit":{"code":"BU029","label":"Software"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"850"}]

Document Information

Modified date:
17 June 2021