IBM Support

PM40158: POOR PERFORMANCE ON REQUESTS WITHOUT AFFINITY DURING HEAVY LOAD

Fixes are available

7.0.0.19: WebSphere Application Server V7.0 Fix Pack 19
8.0.0.1: WebSphere Application Server V8.0 Fix Pack 1
7.0.0.21: WebSphere Application Server V7.0 Fix Pack 21
8.0.0.2: WebSphere Application Server V8.0 Fix Pack 2
8.0.0.3: WebSphere Application Server V8.0 Fix Pack 3
7.0.0.23: WebSphere Application Server V7.0 Fix Pack 23
8.0.0.4: WebSphere Application Server V8.0 Fix Pack 4
7.0.0.25: WebSphere Application Server V7.0 Fix Pack 25
8.0.0.5: WebSphere Application Server V8.0 Fix Pack 5
7.0.0.27: WebSphere Application Server V7.0 Fix Pack 27
8.0.0.6: WebSphere Application Server V8.0 Fix Pack 6
7.0.0.29: WebSphere Application Server V7.0 Fix Pack 29
8.0.0.7: WebSphere Application Server V8.0 Fix Pack 7
8.0.0.8: WebSphere Application Server V8.0 Fix Pack 8
7.0.0.31: WebSphere Application Server V7.0 Fix Pack 31
7.0.0.27: Java SDK 1.6 SR13 FP2 Cumulative Fix for WebSphere Application Server
7.0.0.33: WebSphere Application Server V7.0 Fix Pack 33
8.0.0.9: WebSphere Application Server V8.0 Fix Pack 9
7.0.0.35: WebSphere Application Server V7.0 Fix Pack 35
8.0.0.10: WebSphere Application Server V8.0 Fix Pack 10
7.0.0.37: WebSphere Application Server V7.0 Fix Pack 37
8.0.0.11: WebSphere Application Server V8.0 Fix Pack 11
7.0.0.39: WebSphere Application Server V7.0 Fix Pack 39
8.0.0.12: WebSphere Application Server V8.0 Fix Pack 12
7.0.0.41: WebSphere Application Server V7.0 Fix Pack 41
8.0.0.13: WebSphere Application Server V8.0 Fix Pack 13
7.0.0.43: WebSphere Application Server V7.0 Fix Pack 43
8.0.0.14: WebSphere Application Server V8.0 Fix Pack 14
7.0.0.45: WebSphere Application Server V7.0 Fix Pack 45
8.0.0.15: WebSphere Application Server V8.0 Fix Pack 15
7.0.0.19: Java SDK 1.6 SR9 FP2 Cumulative Fix for WebSphere Application Server
7.0.0.21: Java SDK 1.6 SR9 FP2 Cumulative Fix for WebSphere
7.0.0.23: Java SDK 1.6 SR10 FP1 Cumulative Fix for WebSphere
7.0.0.25: Java SDK 1.6 SR11 Cumulative Fix for WebSphere Application Server
7.0.0.27: Java SDK 1.6 SR12 Cumulative Fix for WebSphere Application Server
7.0.0.29: Java SDK 1.6 SR13 FP2 Cumulative Fix for WebSphere Application Server
7.0.0.45: Java SDK 1.6 SR16 FP60 Cumulative Fix for WebSphere Application Server
7.0.0.31: Java SDK 1.6 SR15 Cumulative Fix for WebSphere Application Server
7.0.0.35: Java SDK 1.6 SR16 FP1 Cumulative Fix for WebSphere Application Server
7.0.0.37: Java SDK 1.6 SR16 FP3 Cumulative Fix for WebSphere Application Server
7.0.0.39: Java SDK 1.6 SR16 FP7 Cumulative Fix for WebSphere Application Server
7.0.0.41: Java SDK 1.6 SR16 FP20 Cumulative Fix for WebSphere Application Server
7.0.0.43: Java SDK 1.6 SR16 FP41 Cumulative Fix for WebSphere Application Server
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APAR status

  • Closed as program error.

Error description

  • By default, WebSphere sets the WLM select policy to 1, which
    forces WLM to select work requests with affinity to a servant
    over those without affinity.  As the load on a server rises,
    and a large number of requests with affinity flow into a server,
    this can cause a severe performance degradation on requests
    without affinity.  Customers experiencing this problem will
    find very long request runtimes for requests without affinity
    (i.e. requests that do not have an HTTP session) in a review of
    performance data for the server.  A deeper review of these
    requests will show that most of the wait time was spent waiting
    for WLM to route the request.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  All users of IBM WebSphere Application      *
    *                  Server V7.0                                 *
    ****************************************************************
    * PROBLEM DESCRIPTION: A WebSphere Application Server for      *
    *                      z/OS                                    *
    *                      server experiences slower response      *
    *                      time                                    *
    *                      for requests that have no established   *
    *                      affinity to a Servant.                  *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    WebSphere creates a WLM dynamic application environment that is
    used for selecting work from the WLM queue.  One of the
    parameters that is passed to WLM is the SELECT_POLICY, and the
    default value that WebSphere uses causes WLM to select work
    targetted to a specific Servant prior to selecting work that
    has
    no affinity.  This SELECT_POLICY is perfectly valid and is
    appropriate in many cases, however in certain specific cases
    an administrator may want to use a different option.
    Currently,
    WebSphere does not allow the SELECT_POLICY to be overridden.
    

Problem conclusion

  • A new property, dynapplenv_wlm_select_policy, was added.  The
    value supplied is passed directly to WLM as the SELECT_POLICY
    of the IWMAEDEF service used to create the dynamic application
    environment.
    
    APAR PM40158 APAR requires changes to documentation.
    
    NOTE: Periodically, we refresh the documentation on our
    Web site, so the changes might have been made before you
    read this text. To access the latest on-line
    documentation, go to the product library page at:
    
    http://www.ibm.com/software/webservers/appserv/library
    
    The following changes to the z/OS version of the WebSphere
    Application Server Version 7.0 Information Center will be
    made available in September, 2011.
    
    The topic "Application server custom properties for z/OS"
    will be updated to include the following description of
    the new dynapplenv_wlm_select_policy environment
    variable:
    
    dynapplenv_wlm_select_policy
    
    Specifies that value that you want passed to the z/OS
    Workload Manager (WLM) as the SELECT_POLICY parameter of
    the IWMAEDEF service.
    
    The IWMAEDEF service is used to create the dynamic
    application environment for the selection of work from the
    WLM queue. For more information about this service, see the
    z/OS WLM documentation for your version of the z/OS
    operating system.
    
    You can specify values of 0, 1 or 2 for this property.
    
    - If you specify a value of 0, the oldest request on either
    the service class or server address space queue is
    selected first.
    - If you specify a value of 1, any requests on the server
    address space queue are always selected first.
    - If you specify a value of 2, any requests on the service
    class queue are always selected first.
    
    Data Type  Integer
    Default  1
    Used by Daemon  No
    
    APAR PM40158 is currently targeted for inclusion in
    Service Level (Fix Pack) 7.0.0.19 of WebSphere
    Application Server V7.0 and Fix Pack 8.0.0.1 of WebSphere
    application Sever V8.0.
    
    Please refer to URL:
    //www.ibm.com/support/docview.wss?rs=404&uid=swg27006970
    for Fix Pack availability.
    

Temporary fix

Comments

APAR Information

  • APAR number

    PM40158

  • Reported component name

    WEBSPHERE FOR Z

  • Reported component ID

    5655I3500

  • Reported release

    700

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-05-26

  • Closed date

    2011-07-15

  • Last modified date

    2011-10-04

  • 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

    WEBSPHERE FOR Z

  • Fixed component ID

    5655I3500

Applicable component levels

  • R700 PSY UK71297

       UP11/09/10 P F109

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.



Document information

More support for: WebSphere Application Server for z/OS
General

Software version: 7.0

Reference #: PM40158

Modified date: 04 October 2011