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PH01768: DEADLOCK POTENTIAL EXISTS WITH ORM XML PROCESSING FOR OPENJPA

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APAR status

  • Closed as program error.

Error description

  • There exists the potential for deadlock with the ORM XML
    processing function in an environment with multiple threads.
    Xerces calls Thread.currentThread().getContextClassloader()
    during its execution to construct the SAXParser (via
    ObjectFactory.createObject()). This means that within the call
    to Xerces, a ClassLoader lock will be attempted on the
    Thread's ContextClassLoader. If there is already a lock with a
    ClassLoader higher in the heirarchy, and another thread with a
    lock on the same ContextClassLoader that is waiting to acquire
    a lock on a higher level ClassLoader, then a deadlock will
    occur. This issue was revealed in a Liberty build break:
    RTC238000, but we maintain common code with tWAS.
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:  All users of IBM WebSphere Application      *
    *                  Server - Java Persistence APA -             *
    *                  JPA 2.0 & OpenJPA                           *
    ****************************************************************
    * PROBLEM DESCRIPTION: There exists the potential for          *
    *                      deadlock with the ORM XMLprocessing     *
    *                      function in an environment with         *
    *                      multiple threads.                       *
    ****************************************************************
    * RECOMMENDATION:                                              *
    ****************************************************************
    There exists the potential for deadlock with the ORM
    XMLprocessing function in an environment with multiple threads.
    Xerces calls Thread.currentThread().getContextClassloader()
    during its execution to construct the SAXParser (via
    ObjectFactory.createObject()). This means that within the call
    to Xerces, a ClassLoader lock will be attempted on the
    Thread's ContextClassLoader. If there is already a lock with a
    ClassLoader higher in the heirarchy, and another thread with a
    lock on the same ContextClassLoader that is waiting to acquire
    a lock on a higher level ClassLoader, then a deadlock will
    occur.
    Exception:
    00000036 SystemOut    O | DEADLOCK DETECTED BY THE JVM, thread
    details:
    00000036 SystemOut    O LargeThreadPool-thread-23 64 BLOCKED
    java.lang.ClassLoader.loadClass(ClassLoader.java:763)
    com.ibm.ws.classloading.internal.UnifiedClassLoader.loadClass0(U
    nifiedClassLoader.java:108)
    com.ibm.ws.classloading.internal.UnifiedClassLoader$Delegation.l
    oadClass(UnifiedClassLoader.java:79)
    com.ibm.ws.classloading.internal.UnifiedClassLoader.loadClass(Un
    ifiedClassLoader.java:103)
    com.ibm.ws.classloading.internal.ThreadContextClassLoader.loadCl
    ass(ThreadContextClassLoader.java:112)
    java.lang.ClassLoader.loadClass(ClassLoader.java:741)
    

Problem conclusion

Temporary fix

Comments

APAR Information

  • APAR number

    PH01768

  • Reported component name

    WEBSPHERE APP S

  • Reported component ID

    5724J0800

  • Reported release

    900

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-08-16

  • Closed date

    2018-08-17

  • Last modified date

    2018-08-17

  • 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 APP S

  • Fixed component ID

    5724J0800

Applicable component levels

  • R850 PSY

       UP

  • R900 PSY

       UP

[{"Business Unit":{"code":"BU053","label":"Cloud \u0026 Data Platform"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"900","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]

Document Information

Modified date:
17 October 2021