23.3. Transaction Recovery
The Transaction Manager coordinates the recovery process and works with Red Hat JBoss Data Grid to determine which transactions require manual intervention to complete operations. This process is known as transaction recovery.
JBoss Data Grid uses JMX for operations that explicitly force transactions to commit or roll back. These methods receive byte arrays that describe the XID instead of the number associated with the relevant transactions.
The System Administrator can use such JMX operations to facilitate automatic job completion for transactions that require manual intervention. This process uses the Transaction Manager's transaction recovery process and has access to the Transaction Manager's XID objects.
23.3.1. Transaction Recovery Process
The following process outlines the transaction recovery process in Red Hat JBoss Data Grid.
Procedure 23.3. The Transaction Recovery Process
- The Transaction Manager creates a list of transactions that require intervention.
- The system administrator, connected to JBoss Data Grid using JMX, is presented with the list of transactions (including transaction IDs) using email or logs. The status of each transaction is either
COMMITTEDorPREPARED. If some transactions are in bothCOMMITTEDandPREPAREDstates, it indicates that the transaction was committed on some nodes while in the preparation state on others. - The System Administrator visually maps the XID received from the Transaction Manager to a JBoss Data Grid internal ID. This step is necessary because the XID (a byte array) cannot be conveniently passed to the JMX tool and then reassembled by JBoss Data Grid without this mapping.
- The system administrator forces the commit or rollback process for a transaction based on the mapped internal ID.
