JR49762: Reduce memory footprint of Price Rule object cache and implement the Sizeable interface.

7.0.0.9 for Developer Express
7.0.0.9 for Developer Professional
7.0.0.9 for Developer Enterprise
7.0.0-WS-WCServer-FP009

APAR status

• Closed as program error.

Error description

• WebSphere Application Server DynaCache provides the capability
  to limit the size in megabytes of each cache instance.
   This feature is available by implementing the
  com.ibm.websphere.cache.Sizeable Java interface.
   Cache entries used by the WebSphere Commerce price rule cache
  with JNDI name dmap/PR_Cache do not implement this interface.
   The result is that this capability cannot be used, and the
  Cache Monitor application shows the size of each cache entry as
  -1 (disabled).
  
   The WebSphere Commerce data cache provides a configuration
  setting to enable the Sizeable interface for other object
  caches, but it does not work for the dmap/PR_Cache object cache.
  
   The WebSphere Commerce data cache also provides a configuration
  setting to reduce the memory footprint of cached objects, but it
  does not work for the dmap/PR_Cache object cache.
  

Local fix

Problem summary

• USERS AFFECTED:
   Any user wishing to limit the size of the price rule cache by
  specifying a size in megabytes.
  
   PROBLEM ABSTRACT:
   Reduce memory footprint of Price Rule object cache and
  implement the Sizeable interface.
  
   BUSINESS IMPACT:
   It is more difficult to manage the memory footprint of the
  price rule cache because the reduceMemory and sizeable data
  cache settings do not work for the dmap/PR_Cache object cache.
  
   Currently, without this feature, customers can limit the size
  of each cache instance by the maximum number of cache entries
  that can be contained in memory, and by the maximum size of the
  disk cache in gigabytes, but they cannot limit the memory
  footprint
  

Problem conclusion

• This iFix implements the com.ibm.websphere.cache.Sizeable
  interface for cache entries used by WebSphere Commerce in the
  price rule cache with JNDI name dmap/PR_Cache when the iFix for
  WebSphere Commerce Feature Pack 4 APAR JR49826 is installed.  It
   also implements the reduceMemory data cache setting.
  
   For backward compatibility, these capabilities are not enabled
  "out of the box" and must be explicitly configured in the
  CrossTransactionCache tag of the InstanceProperties tag in the
  wc-server.xml instance configuration file.  The "sizeable"
  property is defined for the CrossTransactionCache tag:  specify
  sizeable="true" to enable this capability.  The "reduceMemory"
  property is also defined for the CrossTransactionCache tag:
  specify reduceMemory="true" to reduce the memory footprint of
  WebSphere Commerce object caches.
  
   A cache entry that implements the Sizeable interface provides
  an estimate of its memory footprint to DynaCache, allowing
  DynaCache to control the overall memory footprint of each cache
  instance.  Test results have shown that the accuracy of the
  estimate can vary.
  
   Note:  DynaCache will disable this capability for a cache
  instance if it detects that a cache entry that does not
  implement the Sizeable interface (for example custom cacheable
  commands in the baseCache) is placed into a cache instance.
  When this happens, a message like the following is placed in the
  SystemOut.log:
   DYNA1067E: The cache size in MB feature is disabled because the
  cached object is not sizeable.
  
   Note:  While DynaCache automatically implements the Sizeable
  interface for servlet (JSP) cache entries, test results have
  shown that the sizes calculated for these entries can be
  significantly underestimated.  For example, in some tests the
  actual memory footprint of the baseCache servlet cache was
  observed to be significantly larger than the calculated memory
  footprint reported by the cachemonitor application.  For these
  reasons, it is generally not advised to specify the memory size
  in MB for servlet cache instances.
  
   Note:  The normal cache maximum size setting is also used to
  limit the number of cache entries kept in memory.  You should
  continue to specify a reasonable maximum size setting for each
  cache instance, to control the memory footprint and prevent
  potential out of memory conditions.
   -------------------------------------------------------------
   The latest available maintenance information can be obtained
  from the Recommended Fixes for WebSphere Commerce technote:
   http://www.ibm.com/support/docview.wss?rs=3046&uid=swg21261296
  

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

  WC BUS EDITION

• Fixed component ID

  5724I3800

Applicable component levels

• R700 PSY

     UP