PI49170: TransactionCallbackImpl.begin() method is called while processing replica shards. This should only occur on primary

APAR status

• Closed as program error.

Error description

• TransactionCallbackImpl.begin() method is called while
  processing replica shards.  This should only occur on primary
  shards.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED:  WebSphere eXtreme Scale applications using  *
  *                  the TransactionCallback plugin in           *
  *                  with a Loader plugin and connecting to a    *
  *                  backend database.                           *
  ****************************************************************
  * PROBLEM DESCRIPTION: Transactions seem to be hung on         *
  *                      replica shards when the database is     *
  *                      down.                                   *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  The replica is erroneously calling the user implemented
  TransactionCallback.begin() method that in turn is attempting
  to connect to a database that is down. The connection takes
  more then 30 seconds to time out which backs up all incoming
  transactions into the shard.
  

Problem conclusion

• The fix to this solution is two parts:
  1. Customer code that is attempting to establish a database
  connection during the TransactionCallback.begin() method. The
  best practise is to perform a lazy connect. See the section on
  TxID and use of the TransactionCallback interface:
  http://www-01.ibm.com/support/knowledgecenter/SSTVLU_8.6.0/com.i
  bm.websphere.extremescale.doc/cxsloadcon.html?lang=en
  
  2. Even though the customer code is now fixed, the replicas
  will still hit this problem as the callbacks interface is being
  erroneously called. However, the fix will at least ensure that
  the interface is not called on a replica shard and should
  result in performance improvements.
  

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

  WS EXTREME SCAL

• Fixed component ID

  5724X6702

Applicable component levels

• R860 PSY

     UP