PK74719: THREAD HANG CAN OCCUR WHEN MULTIPLE WEB SERVICE REQUESTS ARE RECEIVED BY AN SCA (SERVICE COMPONENT ARCHITECTURE)

APAR status

• Closed as program error.

Error description

• Occasionally, a thread hang occurs when multiple service
  requests are received by a Service Component Architecture (SCA)
  component after a WebSphere Application Server restart.
  The multiple requests are simultaneously attempting to update
  an unsynchronized hashmap, and eventually corrupting it. Once
  the hang occurs, Application Server must be restarted to clear
  the problem. The most notable symptom of the problem is
  evident in the following stack trace excerpt:
  
  Although no exceptions are thrown, you'll witness that several
  threads will be stuck at:
  
  java.util.HashMap.findNonNullKeyEntry(HashMap.java:526)
  at java.util.HashMap.getEntry(HashMap.java:511)
  at java.util.HashMap.get(HashMap.java:497)
  at org.apache.axis2.description.ParameterIncludeImpl.
  getParameter(ParameterIncludeImpl.java:179)
  at org.apache.axis2.description.AxisDescription.getParameter
  (AxisDescription.java:138)
  at org.apache.axis2.description.AxisDescription.getParameter
  (AxisDescription.java:144)
  at org.apache.axis2.jaxws.dispatchers.MustUnderstandUtils.
  getHeaderParameterList(MustUnderstandUtils.java:181)
  at org.apache.axis2.jaxws.dispatchers.MustUnderstandUtils.
  getSEIMethodHeaderParameterList(MustUnderstandUtils.java:167)
  at org.apache.axis2.jaxws.dispatchers.MustUnderstandUtils.
  getHeaderParamaterList(MustUnderstandUtils.java:115)
  at org.apache.axis2.jaxws.dispatchers.MustUnderstandUtils.
  markUnderstoodHeaderParameters(MustUnderstandUtils.java:64)
  at org.apache.axis2.jaxws.dispatchers.MustUnderstandChecker.
  invoke(MustUnderstandChecker.java:40)
  at org.apache.axis2.engine.Phase.invoke(Phase.java:318)
  at org.apache.axis2.engine.AxisEngine.invoke
  (AxisEngine.java:262)
  at org.apache.axis2.engine.AxisEngine.receive
  (AxisEngine.java:169)
  at org.apache.axis2.transport.http.HTTPTransportUtils.
  processHTTPPostRequest(HTTPTransportUtils.java:275)
  at com.ibm.ws.websvcs.transport.http.WASAxis2Servlet.doPost
  (WASAxis2Servlet.java:1331)
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of WebSphere Application Server   *
  *                  that use JAX-WS to send multiple requests   *
  *                  to the same service.                        *
  ****************************************************************
  * PROBLEM DESCRIPTION: Occasionally, the JAX-WS                *
  *                      web service will not complete if a      *
  *                      large number of requests are made to    *
  *                      the same web service.                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Occasionally, the JAX-WS web service will not complete if a
  large number of requests are made to the same web service.
  
  A heap dump of the server may indicate that there are a number
  of threads hanging in the ParameterIncludeImpl.getParameter
  method.
  
  For example:
  java.util.HashMap.findNonNullKeyEntry(HashMap.java:526)
  at java.util.HashMap.getEntry(HashMap.java:511)
  at java.util.HashMap.get(HashMap.java:497)
  at org.apache.axis2.description.ParameterIncludeImpl.
  getParameter(ParameterIncludeImpl.java:179)
  at org.apache.axis2.description.AxisDescription.getParameter
  (AxisDescription.java:138)
  ...
  at com.ibm.ws.websvcs.transport.http.WASAxis2Servlet.doPost
  (WASAxis2Servlet.java:1331)
  

Problem conclusion

• The root of the problem is unsynchronized access to a HashMap.
  The synchronization problem is corrected.
  
  The fix for this APAR is currently targeted for inclusion in
  fixpack 7.0.0.1.  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 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

• R700 PSY

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