IBM Support

PM78861: XML LOCK CONTENTION MAY REDUCE WEB SERVICES PERFORMANCE

Fixes are available

8.5.0.2: WebSphere Application Server V8.5 Fix Pack 2
8.0.0.6: WebSphere Application Server V8.0 Fix Pack 6
8.0.0.7: WebSphere Application Server V8.0 Fix Pack 7
8.0.0.8: WebSphere Application Server V8.0 Fix Pack 8
7.0.0.33: 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
7.0.0.45: Java SDK 1.6 SR16 FP60 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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You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error description

  • The XML parser used by the JAX-WS web services engine has a
shared data structure called a symbol table that it updates
when new XML names are processed. A write lock is sometimes
acquired for mutating this data structure when no updates are
required. A race condition exists which allows the XML parser
to get into a state where it would perpetually lock,
potentially degrading web services performance.

Here is a sample stack trace collected during a period where
locking is occurring:

at sun/misc/Unsafe.park(Native Method)
at
java/util/concurrent/locks/LockSupport.park(LockSupport.java:197
(Compiled Code))
at
java/util/concurrent/locks/AbstractQueuedSynchronizer.parkAndChe
ckInterrupt(AbstractQueuedSynchronizer.java:845(Compiled Code))
at
java/util/concurrent/locks/AbstractQueuedSynchronizer.acquireQue
ued(AbstractQueuedSynchronizer.java:878(Compiled Code))
at
java/util/concurrent/locks/AbstractQueuedSynchronizer.acquire(Ab
stractQueuedSynchronizer.java:1208(Compiled Code))
at
java/util/concurrent/locks/ReentrantReadWriteLock$WriteLock.lock
(ReentrantReadWriteLock.java:956(Compiled Code))
at
com/ibm/xml/xlxp2/scan/util/SymbolMap.resetMap(SymbolMap.java:27
0(Compiled Code))
at
com/ibm/xml/xlxp2/scan/util/SymbolTable.reset(SymbolTable.java:4
4(Compiled Code))
at
com/ibm/xml/xlxp2/api/stax/XMLStreamReaderImpl.reset(XMLStreamRe
aderImpl.java:356(Compiled Code))
at
com/ibm/xml/xlxp2/api/jaxb/JAXBXMLStreamReader.reset(JAXBXMLStre
amReader.java:357(Compiled Code))
at
com/ibm/xml/xlxp2/api/stax/XMLStreamReaderImpl.close(XMLStreamRe
aderImpl.java:749(Compiled Code))
at
com/ibm/xml/xlxp2/api/wssec/WSSXMLStreamReader.close(WSSXMLStrea
mReader.java:122(Compiled Code))
at
com/ibm/xml/xlxp2/api/stax/XMLInputFactoryImpl$XMLStreamReaderPr
oxyImpl.next(XMLInputFactoryImpl.java:193(Compiled Code))
at
com/ibm/xml/xlxp2/api/wssec/WSSXMLInputFactory$WSSStreamReaderPr
oxy.next(WSSXMLInputFactory.java:55(Compiled Code))
at
org/apache/axiom/util/stax/wrapper/XMLStreamReaderWrapper.next(X
MLStreamReaderWrapper.java:225(Compiled Code))
at
org/apache/axiom/util/stax/dialect/DisallowDoctypeDeclStreamRead
erWrapper.next(DisallowDoctypeDeclStreamReaderWrapper.java:34(Co
mpiled Code))
at
org/apache/axiom/om/impl/builder/StAXOMBuilder.parserNext(StAXOM
Builder.java:672(Compiled Code))
at
org/apache/axiom/om/impl/builder/StAXOMBuilder.next(StAXOMBuilde
r.java:214(Compiled Code))
...

Local fix

  • 



Problem summary


    

  • ****************************************************************
* USERS AFFECTED:  All IBM WebSphere Application Server users  *
*                  of JAX-WS and JAXB.                         *
****************************************************************
* PROBLEM DESCRIPTION: XML lock contention may reduce web      *
*                      services performance.                   *
****************************************************************
* RECOMMENDATION:  Install a fix pack that contains this       *
*                  APAR.                                       *
****************************************************************
The XML parser used by the JAX-WS web services engine has a
shared data structure called a symbol table that it updates
when new XML names are processed. A write lock is sometimes
acquired for mutating this data structure when no updates are
required. A race condition exists which allows the XML parser
to get into a state where it would perpetually lock,
potentially degrading web services performance.
Here is a sample stack trace collected during a period where
locking is occurring:
at sun/misc/Unsafe.park(Native Method)
at
java/util/concurrent/locks/LockSupport.park(LockSupport.java:197
(Compiled Code))
at
java/util/concurrent/locks/AbstractQueuedSynchronizer.parkAndChe
ckInterrupt(AbstractQueuedSynchronizer.java:845(Compiled Code))
at
java/util/concurrent/locks/AbstractQueuedSynchronizer.acquireQue
ued(AbstractQueuedSynchronizer.java:878(Compiled Code))
at
java/util/concurrent/locks/AbstractQueuedSynchronizer.acquire(Ab
stractQueuedSynchronizer.java:1208(Compiled Code))
at
java/util/concurrent/locks/ReentrantReadWriteLock$WriteLock.lock
(ReentrantReadWriteLock.java:956(Compiled Code))
at
com/ibm/xml/xlxp2/scan/util/SymbolMap.resetMap(SymbolMap.java:27
0(Compiled Code))
at
com/ibm/xml/xlxp2/scan/util/SymbolTable.reset(SymbolTable.java:4
4(Compiled Code))
at
com/ibm/xml/xlxp2/api/stax/XMLStreamReaderImpl.reset(XMLStreamRe
aderImpl.java:356(Compiled Code))
at
com/ibm/xml/xlxp2/api/jaxb/JAXBXMLStreamReader.reset(JAXBXMLStre
amReader.java:357(Compiled Code))
at
com/ibm/xml/xlxp2/api/stax/XMLStreamReaderImpl.close(XMLStreamRe
aderImpl.java:749(Compiled Code))
at
com/ibm/xml/xlxp2/api/wssec/WSSXMLStreamReader.close(WSSXMLStrea
mReader.java:122(Compiled Code))
at
com/ibm/xml/xlxp2/api/stax/XMLInputFactoryImpl$XMLStreamReaderPr
oxyImpl.next(XMLInputFactoryImpl.java:193(Compiled Code))
at
com/ibm/xml/xlxp2/api/wssec/WSSXMLInputFactory$WSSStreamReaderPr
oxy.next(WSSXMLInputFactory.java:55(Compiled Code))
at
org/apache/axiom/util/stax/wrapper/XMLStreamReaderWrapper.next(X
MLStreamReaderWrapper.java:225(Compiled Code))
at
org/apache/axiom/util/stax/dialect/DisallowDoctypeDeclStreamRead
erWrapper.next(DisallowDoctypeDeclStreamReaderWrapper.java:34(Co
mpiled Code))
at
org/apache/axiom/om/impl/builder/StAXOMBuilder.parserNext(StAXOM
Builder.java:672(Compiled Code))
at
org/apache/axiom/om/impl/builder/StAXOMBuilder.next(StAXOMBuilde
r.java:214(Compiled Code))
...

    



Problem conclusion


    

  • The issue was resolved by adding an additional guard in the
XML parser's symbol table which prevents the perpetual locking
condition from occurring.

The fix for this APAR is currently targeted for inclusion in
fix packs 7.0.0.33, 8.0.0.6 and 8.5.0.2. Please refer to
the Recommended Updates page for delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

    



Temporary fix


    

  • 



Comments


    

  • 



APAR Information




    

  • APAR number
    PM78861
    • 

  • Reported component name
    WEBSPHERE APP S
    • 

  • Reported component ID
    5724J0800
    • 

  • Reported release
    800
    • 

  • Status
    CLOSED  PER
    • 

  • PE
    NoPE
    • 

  • HIPER
    NoHIPER
    • 

  • Special Attention
    NoSpecatt
    • 

  • Submitted date
    2012-12-10
    • 

  • Closed date
    2012-12-17
    • 

  • Last modified date
    2013-12-09
    • 





    

  • 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


    

  • R800  PSY
       UP
    • 

  • R850  PSY
       UP
    • 








      
              
                            

              

              [{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSEQTP","label":"WebSphere Application Server"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.0","Line of Business":{"code":"LOB45","label":"Automation"}}]
              

                          

          
 
        

      

    

      

        

          

            
Document Information


            

            


                        

            Modified date:
            

            29 October 2021
            

            
                      

        


        

        


      

    

  



    

  

  
    
            

          
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