Define Deadlock recovery measures                  

To recover from deadlock, the cycle in the wait-for-graph should be broken. The common technique of doing this is to rollback one or more than one transactions in the cycles until the system shows no further deadlock situation. The choice of the transaction to be rolled back is relies on the following deadlock recovery measures:

• The progress of the transaction and the number of data-items it has employed and modified. It is preferable to rollback a transaction which has just started or has not altered any data-item.
• The amount of computing remaining for the transaction and the number of data items which have yet to be accessed by the transaction. It is favourable not to rollback a transaction it has approximately run to completion and/or it needs very few additional data-items earlier than its termination.
• The relative cost of rolling back a transaction. It is favourable to roll back a less significant or non-critical transaction.