PH26130: ADD PARALLEL CLASS LOADING SUPPORT TO WAS APPLICATION CLASS LOADERS

APAR status

• Closed as new function.

Error description

• The WAS user-space class loaders (application, shared library,
  and extension class loaders) do not currently support the
  optional Java parallel class loading architecture, which allows
  classes of different names to be loaded simultaneously by a
  single class loader. Currently, the loadClass() method itself is
  synchronized in these loaders, so a class loader is locked by
  all class loads performed using it.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server                                      *
  ****************************************************************
  * PROBLEM DESCRIPTION: WAS class loaders do not support        *
  *                      parallel                                *
  *                      class loading                           *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Java 7 modified the ClassLoader.loadClass() API to include
  optional support for parallel class loading, removing the
  synchronization from the loadClass() method and instead locking
  on a combination of the class loader and the class being loaded,
  allowing multiple threads to simultaneously use the same class
  loader. WAS' application and server level loaders did not
  implement this optional behavior, which could lead to increased
  contention and performance issues in environments where multiple
  threads were attempting to load classes using the same class
  loader.
  

Problem conclusion

• Server class loaders have been updated to support Java parallel
  class loading.
  
  The fix for this APAR is targeted for inclusion in fix pack
  9.0.5.6. For more information, see 'Recommended Updates for
  WebSphere Application Server':
  https://www.ibm.com/support/pages/node/715553
  

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

• R900 PSY

     UP