Brother-Eagle® DB2 Performance
Advice: Deadlocks

This value represents the number of deadlocks that have occurred, also known as deadly embraces. Deadlocks are the most severe locking problem of all. With Brother-Eagle V2.2, the number of deadlocks shown is the delta value of new deadlocks that occurred during the most recent interval. Prior to V2.2, Brother-Eagle reported the total count of deadlocks.

In a deadlock situation, two connections require locks on resources that the other transaction is holding. DB2 must select one of the transactions to be rolled back.

Deadlocks slow down applications according to the deadlock check time database configuration parameter, plus the potentially expensive cost of performing rollbacks.

• Brother-Eagle will indicate a warning if 5 or more deadlocks have occurred.
• Brother-Eagle will indicate an alert if 10 or more deadlocks have occurred.
• To view current locks, Right Click on Locks Currently Waiting and select “Show Locks”. Authorized users can terminate connections holding locks. For additional assistance in resolving DB2 Deadlocks, Brother-Panther™ stores Deadlock History in its performance repository.

Locking problems are a symptom of poor SQL performance. Deadlocks can also occur when different transactions are updating the same tables but in different orders. If you find deadlocks repeatedly occurring on certain tables, carefully review the indexes on the table to ensure there are no indexes that have very low cardinalities, skew, or redundant indexes.

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