Wait Type LCK_M_BU_ABORT_BLOCKERS

Wait statistics, in the context of SQL Server, refer to the amount of time that a query spends waiting to access data in the database. When a client application requests data from the database, the request is placed in a queue and the client application must wait for its turn to access the data. The time that the query spends waiting is called a "wait" and is tracked by SQL Server. This information can be used to identify potential performance bottlenecks and optimize the performance of the database. Wait statistics are commonly used by database administrators to diagnose and troubleshoot performance issues in SQL Server.

SQL Server uses wait types to signal where processes may encounter delays. The LCK_M_BU_ABORT_BLOCKERS wait type occurs when a transaction is waiting for a Bulk Update (BU) lock, but the system is configured to abort blocking transactions to proceed. This wait type highlights lock contention scenarios and the systems effort to resolve conflicts while maintaining transactional integrity.

What Is the LCK_M_BU_ABORT_BLOCKERS Wait Type?

The LCK_M_BU_ABORT_BLOCKERS wait type appears when SQL Server is attempting to acquire a Bulk Update lock on a resource. Bulk Update locks are used in operations like bulk insert or update statements, which require controlled access to ensure efficient data modifications. When a blocking transaction prevents the BU lock from being acquired, SQL Server may abort the blocking transaction based on the configuration, leading to this wait type.

This mechanism helps SQL Server balance performance and concurrency, especially in high-volume operations.

When Does LCK_M_BU_ABORT_BLOCKERS Appear?

This wait type can occur in the following scenarios:

• Bulk Data Operations – During bulk insert, update, or merge operations that require exclusive access to certain data or pages.
• High Contention – In environments with high concurrency, where multiple transactions compete for the same resources.
• Blocked Transactions – When other long-running transactions hold locks on the resource needed for the bulk operation.
• Configuration for Abort Blockers – When SQL Server is configured to terminate blocking transactions to allow the bulk operation to proceed.

Why LCK_M_BU_ABORT_BLOCKERS Waits Matter

While some LCK_M_BU_ABORT_BLOCKERS waits are normal in high-concurrency systems, prolonged or frequent waits can indicate inefficiencies or potential bottlenecks. Common causes include:

• Long-Running Transactions – Transactions holding locks for extended periods can delay bulk operations.
• High Concurrency – Intense competition for the same resources can increase wait times.
• Large Bulk Operations – Operations involving significant amounts of data may require more time to acquire and hold locks.
• Poor Indexing – Inefficient indexing can result in broader locking and higher contention.

How to Address LCK_M_BU_ABORT_BLOCKERS Waits

If this wait type appears frequently, consider these strategies to minimize its impact:

• Optimize Queries – Ensure queries are efficient and minimize the scope of data being locked during bulk operations.
• Break Down Bulk Operations – Divide large bulk operations into smaller batches to reduce the time locks are held.
• Monitor Blocking Transactions – Identify and resolve long-running transactions that may be causing contention.
• Improve Indexing – Use proper indexing strategies to reduce the resources locked during bulk operations.
• Schedule Bulk Operations – Run bulk operations during periods of low activity to minimize contention.

Monitoring LCK_M_BU_ABORT_BLOCKERS Waits

To monitor this wait type, use the Historic Waits Monitoring feature in Database Health Monitor. This tool provides detailed insights into wait statistics over time, helping you identify patterns and pinpoint sources of contention. Regular monitoring allows for proactive optimization and improved performance in high-concurrency environments.

Stedman Solutions specializes in SQL Server performance tuning and optimization. Whether you’re dealing with LCK_M_BU_ABORT_BLOCKERS waits or other performance challenges, our Database Health Monitor tool offers comprehensive insights, and our managed services provide expert support to keep your SQL Server environment running smoothly. Contact us today to learn how we can help enhance your SQL Server performance.

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Applies to

Related Waits

See Also

• More About LCK_M_BU_ABORT_BLOCKERS