PI50694: CLASSCASTEXCETPION IS THROWN IN JPA WHEN QUERYCACHE IS ENABLED.

8.0.0.12: WebSphere Application Server V8.0 Fix Pack 12
8.5.5.9: WebSphere Application Server V8.5.5 Fix Pack 9
8.5.5.10: WebSphere Application Server V8.5.5 Fix Pack 10
8.5.5.11: WebSphere Application Server V8.5.5 Fix Pack 11
8.0.0.13: WebSphere Application Server V8.0 Fix Pack 13
8.5.5.12: WebSphere Application Server V8.5.5 Fix Pack 12
8.0.0.14: WebSphere Application Server V8.0 Fix Pack 14
8.5.5.13: WebSphere Application Server V8.5.5 Fix Pack 13
8.0.0.15: WebSphere Application Server V8.0 Fix Pack 15
8.5.5.14: WebSphere Application Server V8.5.5 Fix Pack 14
8.5.5.15: WebSphere Application Server V8.5.5 Fix Pack 15
8.5.5.17: WebSphere Application Server V8.5.5 Fix Pack 17
8.5.5.20: WebSphere Application Server V8.5.5.20
8.5.5.18: WebSphere Application Server V8.5.5 Fix Pack 18
8.5.5.19: WebSphere Application Server V8.5.5 Fix Pack 19
8.5.5.16: WebSphere Application Server V8.5.5 Fix Pack 16
8.5.5.21: WebSphere Application Server V8.5.5.21

APAR status

• Closed as program error.

Error description

• When query cache is enabled, under high load, the caching
  process did not handle correctly and intermittently threw
  ClassCastException. Example:
  java.lang.ClassCastException: java.lang.String incompatible
  with java.lang.Integer
  at org.apache.openjpa.jdbc.kernel.
  PreparedSQLStoreQuery$PreparedSQLExecutor.toParameterArray
  (PreparedSQLStoreQuery.java:160)
  at
  org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:
  857)
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server V8.0.0, V8.5.0, and V8.5.5           *
  *                  who make use of OpenJPA's QuerySQLCache.    *
  ****************************************************************
  * PROBLEM DESCRIPTION: Sporadic ClassCastException occurs      *
  *                      under heavy load when OpenJPA's         *
  *                      QuerySQLCache is enabled.               *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  When OpenJPA's QuerySQLCache is enabled, there exists the
  potential for the following ClassCastException to occur
  sporadically:
  java.lang.ClassCastException: java.lang.String
  incompatible with java.lang.Integer
  at
  org.apache.openjpa.jdbc.kernel.PreparedSQLStoreQuery$PreparedSQL
  Executor.toParameterArray(PreparedSQLStoreQuery.java:160)
  at
  org.apache.openjpa.kernel.QueryImpl.execute(QueryImpl.java:857)
  ... 23 more
  This exception can occur when two or more threads attempt to
  run the same query at the same time, using query
  parameters.  For example, take this query:
  q = em.createQuery("select o from MyEntity o where
  upper(o.comment) like :mrn");
  q.setParameter("mrn", "test");
  q.getResultList();
  When this query is run, an entry is created for this query in
  OpenJPA's QuerySQLCache.  If many threads run this same exact
  query at the same exact time, there is the potential for two
  or more threads to attempt to initialize the cached query. In
  most cases the cached query is only initialized once by one
  thread.  There exists a race condition where by the cached
  query could be initialized more than once.  This sets into
  motion a scenario which can cause a ClassCastException when
  the cached query is run. The window or time in which this can
  occur is very narrow and complicated (many things have to
  aline perfectly).  The details are beyond the scope of this
  APAR.  However, suffice it to say that in the absence of this
  fix, the issue can be worked around by disabling the OpenJPA
  QuerySQLCache, as described in the OpenJPA documentation.
  

Problem conclusion

• With this fix, code has been added to OpenJPA to ensure that a
  query is initialized and cached by only one thread. In other
  words, code has been added to properly synchronize the code
  path which caused the ClassCastException.
  
  The fix for this APAR is currently targeted for
  inclusion in Service Levels (Fix Packs) 8.0.0.12 and 8.5.5.9
  of WebSphere Application Server versions 8.0.0 and 8.5.5.
  
  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

  WEBS APP SERV N

• Fixed component ID

  5724H8800

Applicable component levels

• R800 PSY

     UP

• R850 PSY

     UP