JR53849: Data Cache enhancement to prevent multiple threads executing the same query simultaneously

APAR status

• Closed as program error.

Error description

• The WebSphere Commerce Data Cache caches database query result
  sets. In particular after cache clear scenarios, if there
  are long running queries, it is possible to find multiple
  threads executing the same query simultaneously, to retrieve the
   same data. Allowing a single thread to fetch the data that can
  later be used by other threads should improve performance.
  

Local fix

Problem summary

• USERS AFFECTED:
  WebSphere Commerce V7 administrators who see multiple threads
  executing the same query simultaneously which can cause
  performance issues
  
  PROBLEM ABSTRACT:
  Data Cache enhancement to prevent multiple threads executing the
   same query simultaneously
  
  BUSINESS IMPACT:
  Shoppers can have a negative shopping experience when the page
  is taking too long to load due to performance issues
  
  RECOMMENDATION:
  

Problem conclusion

• This enhancement will only allow one thread at a time to execute
   the same query with the same parameters.
  To implement this behavior, a new data cache configuration
  setting is added in the CrossTransactionCache tag in the
  InstanceProperties tag in the wc-server.xml instance
  configuration file:
  
  avoidConcurrentCacheMiss="true"
  
  Similar to many other data cache settings, this setting can be
  specified at the logical cache, object cache, and global level.
  
  The default value is "false".  When this setting is "true", a
  cache miss will block threads about to concurrently execute a
  cache miss for the same cache entry.  Once the cache miss has
  been processed, the blocked threads continue, and if the cache
  entry exists (which it normally should), will encounter a cache
  hit.
  

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