IBM Support

PM20539: CLASSLOADER MEMORY LEAK.

Fixes are available

7.0.0.15: WebSphere Application Server V7.0 Fix Pack 15 for AIX
7.0.0.15: Java SDK 1.6 SR9 Cumulative Fix for WebSphere Application Server
7.0.0.15: WebSphere Application Server V7.0 Fix Pack 15 for HP-UX
7.0.0.15: WebSphere Application Server V7.0 Fix Pack 15 for IBM i
7.0.0.15: WebSphere Application Server V7.0 Fix Pack 15 for Linux
7.0.0.15: WebSphere Application Server V7.0 Fix Pack 15 for Solaris
7.0.0.15: WebSphere Application Server V7.0 Fix Pack 15 for Windows
7.0.0.17: WebSphere Application Server V7.0 Fix Pack 17
7.0.0.17: Java SDK 1.6 SR9 FP1 Cumulative Fix for WebSphere Application Server
7.0.0.19: WebSphere Application Server V7.0 Fix Pack 19
7.0.0.21: WebSphere Application Server V7.0 Fix Pack 21
7.0.0.23: WebSphere Application Server V7.0 Fix Pack 23
7.0.0.25: WebSphere Application Server V7.0 Fix Pack 25
7.0.0.27: WebSphere Application Server V7.0 Fix Pack 27
7.0.0.29: WebSphere Application Server V7.0 Fix Pack 29
6.1.0.47: WebSphere Application Server V6.1 Fix Pack 47
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
7.0.0.35: WebSphere Application Server V7.0 Fix Pack 35
7.0.0.37: WebSphere Application Server V7.0 Fix Pack 37
7.0.0.39: WebSphere Application Server V7.0 Fix Pack 39
7.0.0.41: WebSphere Application Server V7.0 Fix Pack 41
7.0.0.43: WebSphere Application Server V7.0 Fix Pack 43
7.0.0.45: WebSphere Application Server V7.0 Fix Pack 45
6.1.0.43: Java SDK 1.5 SR13 Cumulative Fix for WebSphere Application Server
6.1.0.45: Java SDK 1.5 SR14 Cumulative Fix for WebSphere Application Server
6.1.0.47: Java SDK 1.5 SR16 Cumulative Fix for WebSphere Application Server
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

  • Classloader memory leak in Naming CacheManager in the servant
    region. Leak occurs if applications are started and stopped many
    times such as in a stress test.
    Example of leak:
    0x14c52e700 com/ibm/ws/naming/jcache/CacheKey@66c366c3
      0x14ad88ad0 java/util/HashMap$Entry@67146714
       0x14471a228 java/util/HashMap$Entry@55905590
        0x14e2a8d58 [Ljava/util/HashMap$Entry;@711b711b
          0x128487320 class
    com/ibm/ws/naming/jcache/CacheManager@6bc46bc4
           0x128a99668
    org/eclipse/osgi/internal/baseadaptor/DefaultClassLoader@7f5f7f5
    f
            [truncating at system class LEAK]
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  Users of IBM WebSphere Application Server   *
    *                  Network Deployment versions 7.0 on z/OS     *
    ****************************************************************
    * PROBLEM DESCRIPTION: Slow memory leak of classloader in      *
    *                      CacheManager when applications are      *
    *                      started and stopped repeatedly.         *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    Naming cache is used to speed up lookup.  For java namespace
    caches, CacheManager uses the associated context classloader
    as part of the key to lookup the cache instance.  This works as
    design on distributed platforms.  However, since the
    NameServerImpl,  which registers an deployment listener to
    clears out caches during the application stop, runs in the
    control region, while the CacheManager and runs in the servant
    region, the classloader did not get clear out on z/OS.  Thus, a
    minor memory leak of classloader is seen in CacheManager in the
    servant region on z/OS when applications is started and
    stopped repeatedly over time.  This memory leak should only be
    a concern during stress test.  Under normal usage, this leak
    does not have a noticeable impact.
    

Problem conclusion

  • The ServantNameServiceImpl registers a listener to remove
    classloader used as cache key in the CacheManager when
    application is stopped.  The slow memory leak of classloaders
    in servant region is removed.
    
    APAR PM20539 is currently targeted for inclusion in Service
    Level 7.0.0.15 of WebSphere Application Server.
    
    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

    PM20539

  • 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

    2010-08-13

  • Closed date

    2010-11-08

  • Last modified date

    2011-04-04

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

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

    PM43071

Fix information

  • Fixed component name

    WEBSPHERE FOR Z

  • Fixed component ID

    5655I3500

Applicable component levels

  • R700 PSY UK65060

       UP11/03/04 P F103

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 #: PM20539

Modified date: 04 April 2011