JR54799: Data Cache enhancement to prevent multiple REST GET threads from 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, you might notice multiple threads
  executing the same query simultaneously to retrieve the same
  data.
  

Local fix

Problem summary

• USERS AFFECTED:
  WebSphere Commerce Version 7 or Version 8 administrators who see
  multiple threads executing the same query simultaneously, which
  can cause performance issues.
  
  
  
  PROBLEM ABSTRACT:
  Data Cache enhancement to prevent multiple REST GET threads from
   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

• APAR JR53849 improved performance by allowing a single thread to
   fetch the data that can later be used by other threads.
  This APAR expands on JR53849 to allow the same behavior for REST
   GET requests.
  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".  If you set the value to "true", a
   cache miss will block threads about to concurrently execute a
  cache miss for the same cache entry. Once the cache miss is
  processed, the blocked threads continue, and if the cache entry
  exists (which it normally should), the thread 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