PH12606: STORE APPLICATION CLASSES IN SHARED CLASS CACHE TO IMPROVE SERVER STARTUP

9.0.5.0: WebSphere Application Server traditional Version 9.0.5 Refresh Pack
9.0.5.1: WebSphere Application Server traditional Version 9.0.5 Fix Pack 1
9.0.5.2: WebSphere Application Server traditional Version 9.0.5 Fix Pack 2
9.0.5.3: WebSphere Application Server traditional Version 9.0.5 Fix Pack 3

APAR status

• Closed as new function.

Error description

• Only product classes were stored in the IBM JDK shared class
  cache.  By adding application classes to the shared class
  cache, applications can start up faster on subsequent server
  starts.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  All users of IBM WebSphere Application      *
  *                  Server                                      *
  ****************************************************************
  * PROBLEM DESCRIPTION: Improve startup time and reduce memory  *
  *                      footprint using java class sharing.     *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  Since WebSphere Application Server version 6.1, Java class
  sharing -- IBM JVM option "-Xshareclasses" -- is enabled by
  default for Application Server, Node Agent, and Deployment
  Manager processes in order to improve startup time and
  reduce memory footprint (1, 2).
  APAR PH12606 extends Java class sharing support within
  WebSphere Application Server to include Java
  Enterprise Edition applications, shared libraries and isolated
  resource providers. Specifically, the classloader types which
  load these entities have been upgraded to store and load
  class definitions to and from the server's Java shared class
  cache.
  This new application class sharing support introduced by APAR
  PH12606 will enable and disable according to the value of the
  "-Xshareclasses" option configured for each server process
  type.  Visit Knowledge Center topic "Tuning the IBM virtual
  machine for Java" (2) to learn more about enabling java class
  sharing in WebShere Application Server.
  References:
  1. WebSphere Application Server Network Deployment 9.0,
  "Tuning the IBM virtual machine for Java".
  https://www.ibm.com/support/knowledgecenter/SSAW57_9.0.0/
  com.ibm.websphere.nd.multiplatform.doc/ae/
  tprf_tunejvm_v61.html
  2. IBM SDK, Java Technology Edition 8.0.0, "Class data
  sharing".
  https://www.ibm.com/support/knowledgecenter/en/SSYKE2_8.0.0/
  com.ibm.java.vm.80.doc/docs/shrc.html
  

Problem conclusion

• APAR PH12606 enables Java Enterprise Edition application class
  sharing in Application Server, Node Agent, and Deployment
  Manager processes that use the IBM JVM.
  
  The fix for this APAR is currently targeted for inclusion in
  fix pack 9.0.5.0.  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

• R900 PSY

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